Production apparatus of monodisperse particle and production process of monodisperse particle and monodisperse particle produced by the process
It is the object to provide a production process of monodisperse particle in which monodisperse particle with uniform particle size (particle diameter) can be stably mass-produced, and monodisperse particle produced by this process, and its production apparatus. The supply pipe diameter &dgr;f is set to be greater than the orifice diameter &dgr;o and the internal and external pressure of the slurry retention part b is controlled, and this allows to facilitate supply of the slurry through the supply pipe (21c), and continuously and efficiently supply the slurry, and then to produce monodisperse particle with uniform particle size (particle diameter).
[0001] 1. Field of the Invention
[0002] This invention relates to production process of monodisperse particle for producing monodisperse particle containing particles of substantially uniform particle size, and monodisperse particle, and further its apparatus.
[0003] 2. Description of the Related Art
[0004] Small particles, that is, small monodisperse particles are now increasing demand in various kinds of science and technology. For example, latex particle which is well known as small monodisperse particle, and produced by sol-gel process, has standard deviation of approximately 10% of average particle diameter in particle size (particle diameter) distribution, and is used as standard size particle in electron microscope observation. In semi-conductor industry, spherical soldering powder of uniform particle size (particle diameter) of 30 &mgr;m to 40 &mgr;m is required. Further, in HIP forming of alloy powder, spherical powder of uniform particle size (particle diameter) is required to prevent formation of uneven space that causes fatal defective for material.
[0005] As a process to produce small monodisperse particle, there is sol-gel process as described before, if limiting to oxide small particle of below a few &mgr;m, while there is plasma rotation electric pole process (PREP process) if particles of greater than 100&mgr;m are required. Moreover, when certain degree of particle size (particle diameter) is acceptable, general process to mechanically classify the atomized powder through such as comb is practical.
[0006] However, in conventional process, classification operation is inevitable, and further it is generally difficult to control the particle size widely, that is, to obtain the monodisperse particle of desired particle size. As mentioned before, sol-gel process is limited to producing small particle of 0.1 &mgr;m to 1.2 &mgr;m. Further, in the PREP process, rotational stability of electric poles limits the production of the particle to the diameter of approximately 100 &mgr;m. In order to expand the application of the monodisperse particle in the present, it has been desired to develop the production process that requires no classification operation, and allows to control any particle size (particle diameter) freely.
[0007] For this purpose, the applicants proposed production process and apparatus of spherical monodisperse particle that allows to control particle size (particle diameter) of individual particles artificially and widely, and to stably produce uniform and spherical monodisperse particle closer to sphericity in Japanese patent application Hei 3-317096 “Production process and apparatus of spherical monodisperse particle” (see to Japanese Laid Open Patent Publication Hei 6-184607).
[0008] This Japanese patent application Hei 3-317096 disclosed to provide the production process of spherical monodisperse particle that specifies production process of monodisperse particle and this process characterized in that piezoelectric actuator generates pulse pressure, and the pressure is transmitted to diaphragm through transmission rod, and further is transmitted to molten metal closely contacting to this diaphragm, further, by displacement of the diaphragm toward the molten metal greater than critical displacement, the molten metal is ejected into inert gas flow one by one as monodisperse particle from orifice provided on the container retaining the molten metal and is spheroidized, after cooling in water for cooling, the spherical monodisperse particles are recaptured.
[0009] According to the production process of spherical monodisperse particle according to the prior application as mentioned above, and the production apparatus of spherical monodisperse particle specifying this production process, high-accurate spherical monodisperse particles are in fact possibly produced.
[0010] However, it is not sufficient to determine suitability of the monodisperse particle for various kinds of applications by the only fact that high-accurate spherical monodisperse particles can be produced. In other words, unless the multi-purpose monodisperse particles suitable for various applications by itself can be definite, it is difficult to produce the monodisperse particle industrially and cheaply. For this reason, there exists a costly problem for industrial application of the monodisperse particle to various fields.
[0011] In addition, because the above production apparatus of the spherical monodisperse particle specifying the production process of spherical monodisperse particle according to the prior application, obtains uniform particles by injecting the molten metal to inert gas by certain amount, the productivity of the monodisperse particles depends only on the interval of injecting molten metal. As long as the injection of the molten metal is carried out by the mechanism that the pulse pressure is transmitted to the diaphragm through the transmission rod, this interval of injection of molten metal is limited itself. Therefore, in this sense, the above production apparatus of the spherical monodisperse particle specifying the production process of spherical monodisperse particle according to the prior application has problem to be solved from the point of suitability for mass-production.
SUMMARY OF THE INVENTION[0012] Taking the problems in the above prior arts into account, the object of this invention is to provide production process of monodisperse particle in which monodisperse particle suitable for various fields, which is multi-purpose, is allowed to be industrially and cheaply produced, in particular, no classification operation is required, and particle size (particle diameter) of individual particles is allowed to be widely and artificially controlled, and then the monodisperse particle of uniform particle size (particle diameter) is allowed to be stably mass-produced, the monodisperse particle produced by this process and production apparatus.
[0013] To overcome the above problems, the-applicants considered the industrial application of the above production process and production apparatus of spherical monodisperse particle as well as obtaining the multi-purpose monodisperse particle, and succeeded in finding the fundamental conditions to produce highly multi-purpose monodisperse particle industrially and cheaply. At the same time, the applicants further improved the above production process and production apparatus of spherical monodisperse particle, and reached to the production process of monodisperse particle in which handling, setting and control are easy, and monodisperse particles are suitably mass-produced as well as monodisperse particles in high melting point are possibly produced, and the monodisperse particles produced by this process as well as its production apparatus.
[0014] Specifically, the production apparatus of monodisperse particles according to the invention is characterized to have retention container for flowable material to retain the flowable material, supply pipe being passage to supply the flowable material from material container to the retention container for flowable material, diaphram closely contacting the retention container for flowable material, orifice provided at the bottom of the retention container for flowable material, piezoelectric actuator generating given pulse pressure, transmission rod transmitting the pulse pressure generated by the piezoelectric actuator to the diaphram, recovery part recovering the flowable material ejected per amount of unit located at the lower part of the orifice plate.
[0015] Furthermore, the production apparatus of monodisperse particles according to the invention is characterized to have retention container for flowable material to retain the flowable material, supply pipe being passage to supply the flowable material from material container to the retention container for flowable material, nozzle portion provided on the retention container for flowable material, orifice for ejecting the flowable material in the retention container for flowable material provided on the nozzle portion, piezoelectric actuator generating given displacement, transmission rod transmitting the displacement of the piezoelectric actuator to the nozzle portion as displacement of the cylinder rod inserted into the nozzle portion, and recovery part recovering the flowable material ejected per amount of unit.
[0016] The production apparatus of monodisperse particles according to the invention as constituted above allows to require no classification operation, to widely and artificially control the particle size (particle diameter) of individual particles, and to stably mass-produce the monodisperse particles of uniform particle size (particle diameter). Besides that, continuous supply of the flowable material to the retention container for flowable material through the supply pipe allows continuous and stable production of monodisperse particles.
[0017] This invention is constituted so that diameter &dgr;f of supply pipe of the supply pipe and diameter &dgr;o of orifice of the orifice satisfies the equation 1.
&dgr;f>&dgr;o (Equation 1)
[0018] Further, in this invention, it is preferable to set the diameter of the supply pipe to from 100 to 900 &mgr;m.
[0019] This allows to satisfy the (Equation 1), to supply the flowable material to the retention container for flowable material smoothly and to continuously, stably produce the monodisperse particles.
[0020] Where the diameter of the supply pipe is less than 100 &mgr;m, it is difficult to supply the flowable material to the retention container for flowable material, and impossible and inconvenient to continuously, stably eject.
[0021] On the other hand, where the diameter of the supply pipe exceeds 900 &mgr;m, escape of the flowable material to the supply pipe becomes large and displacement of the diaphram or the cylinder rod becomes very large, and then the flow of the flowable material to the orifice becomes unstable, therefore, it becomes difficult to continuously and stably eject, as a result, it is not preferable.
[0022] Further, this invention is constituted so that diameter &dgr;f of supply pipe of the supply pipe and diameter &dgr;o of orifice of the orifice satisfies the equation 2.
0.5<k=(&dgr;f)2/{(&dgr;o)2+(&dgr;f)2}≦0.95 (Equation 2)
[0023] Where K is loss coefficient, and quantitatively defined as escape of the flowable material to the supply pipe to the liquid amount (Vd) forced by the diaphram or cylinder rod.
[0024] In this invention, setting of the loss coefficient k as described above allows to design the portion of the orifice and to set the displacement of the diaphram.
[0025] Where the k is less than 0.5, it is difficult to supply the flowable material to the retention container for flowable material, and impossible and inconvenient to continuously, stably eject.
[0026] On the other hand, where the K exceeds 0.95, escape of the flowable material to the supply pipe becomes large and displacement of the diaphram or the cylinder rod becomes very large, and then the flow of the flowable material to the orifice becomes unstable, therefore, it becomes difficult to continuously and stably eject, as a result, it is not preferable.
[0027] Furthermore, the production apparatus of monodisperse particles according to the invention is characterized to have retention container for flowable material to retain the flowable material, container for material supplying flowable material to the retention container for flowable material, nozzle portion provided on the retention container for flowable material, orifice for ejecting the flowable material in the retention container for flowable material provided on the nozzle portion, piezoelectric actuator generating given displacement, transmission rod transmitting the displacement of the piezoelectric actuator to the nozzle portion as displacement of the cylinder rod inserted into the nozzle portion, and recovery part recovering the flowable material ejected per amount of unit, and space area Af between inside of the nozzle and the cylinder rod and cross section Ao of the orifice satisfy the (Equation 3).
Af>Ao (Equation 3)
[0028] This allows to facilitate the supply of the flowable material to the retention container for flowable material, to supply smoothly, and to continuously, stably produce the monodisperse particles.
[0029] Further, the production apparatus of monodisperse particles according to the invention is provided with measuring device for internal pressure of the material container, measuring device for external pressure of the material container, controller to control the internal and external pressure of the material container, as well as the material container is provided with heating device.
[0030] As described above, the production apparatus of monodisperse particles according to the invention is provided allows to control the internal and external pressure at any pressure, therefore, to facilitate supply of flowable material through the supply pipe, to supply the flowable material continuously and efficiently, and to stably mass-produce monodisperse particles of uniform particle size (particle diameter).
[0031] By ejecting the flowable material from the orifice into the recovery portion through the transmission rod, cylinder rod and cavity by the piezoelectric actuator, the production apparatus of monodisperse particles according to the invention allows to mass-produce the monodisperse particles of uniform particle size (particle diameter) more stably.
[0032] The orifice may be provided on orifice plate having a plural orifices. This allows the production process of monodisperse particles to eject flowable material from a plural orifices to produce monodisperse particles, therefore, to achieve productivity that has never been achieved only by shortening the ejecting interval by using single orifice, and to realize high mass-production possibility.
[0033] Providing the nozzle portion with cavity allows to firmly and stably eject set amount when ejecting the flowable material from the orifice through the transmission rod, cylinder rod and cavity by displacement of the piezoelectric actuator.
[0034] By forming the cavity at the bottom of the retention container for flowable material, it is possible to fall liquid drop straight down without opposing gravity, and to prevent variation of characteristic of the obtained monodisperse particles caused by disturbance affected by gravity when ejecting liquid drop. Adversely, by falling liquid drop straight down without opposing gravity, it is possible to function gravity as a stable control factor in production of monodisperse particles. Further, intervention of foam into the material is not allowed, therefore, it is possible to high-efficiently apply energy provided from outside to the flowable material.
[0035] By making the flowable material molten metal and ejecting the molten metal as liquid drop from the orifice, it becomes easy to control the ejecting amount as liquid drop, and it becomes possible to enhance the uniformity of each particle forming the obtained monodisperse particles.
[0036] The orifices provided on the orifice plate can be provided to be removable.
[0037] This allows to control particle diameter of recovered monodisperse particles high-accurately and easily by setting the diameter of the orifice removably provided on the orifice plate.
[0038] By providing the cylinder rod with precision positioning means, it is possible to easily and precisely control and manage the particle diameter of the obtained monodisperse particles.
[0039] It is preferable that the particle forming the monodisperse particles are metallic glass particle. Metallic glass particle has high strength and high corrosion resistance, therefore, for example it is suitable to apply the monodisperse particles according to this invention to parts of micro-machine such as miniature bearing, is widely applied to various kinds of applications.
[0040] Further, the production process of monodisperse particles is characterized in that flowable material is supplied from material container to retention container for monodisperse particles through supply pipe, and the flowable material retained in the retention container for monodisperse particles is ejected to recovery part through orifice by displacement transmission means connected to piezoelectric actuator generating given displacement and recovered, wherein the supply pipe diameter &dgr;f of the supply pipe is greater than the orifice diameter &dgr;o of the orifice.
[0041] Further, the production process of monodisperse particles is characterized in that flowable material is supplied from material container to retention container for monodisperse particles through supply pipe, and the flowable material retained in the retention container for monodisperse particles is ejected to recovery part from the orifice of orifice plate having a plural orifices by displacement transmission means connected to piezoelectric actuator generating given displacement and recovered, wherein the flow rate per unit of the flowable material in the supply pipe is controlled to be greater than the flow rate per unit of the flowable material from the orifice.
[0042] As described above, in the production process of monodisperse particles according to the invention, the supply pipe diameter &dgr;f of the supply pipe is set to be greater than the orifice diameter &dgr;o of the orifice, or the flow rate per unit of flowable material in the supply pipe is controlled to be greater than that in the orifice, therefore, the flowable material is continuously and stably supplied to the retention container for flowable material through the supply pipe, and then it is possible to continuously and stably produce monodisperse particle. In other words, the state that the flowable material supplied through the supply pipe is filled in the retention part for monodisperse particle is usually kept, it is possible to perform high-speed continuous production. Even in performing the high-speed continuous production, by controlling displacement of displacement transmission means connected to the piezoelectric actuator as primary control factor, it is possible to produce monodisperse particle with very little variation of particle diameter and small standard deviation.
[0043] Where, as the above displacement transmission means, the combination of rod and diaphram disclosed in Japanese Laid Open Kokai Hei 6-184607 according to the application by this applicant described before and the cylinder rod having same workability as this are suitably used.
[0044] Further, in the production process of monodisperse particle according to this invention, the difference in pressure between inside and outside of the material container is measured, and the internal and external pressure of the material container is controlled at given value based on the measurement.
[0045] As described above, in the production process of monodisperse particle according to this invention, the internal and external pressure of the material container is controlled at given value, therefore, the flowable material is facilitated to be supplied through the supply pipe, the flowable material is supplied continuously and efficiently, and as a result, it is possible to stably mass-produce monodisperse particle of uniform particle size (particle diameter).
[0046] Further, the above difference in pressure is controlled based on the (Equation 4).
0≦P<Pc (Equation 4)
[0047] P: Difference in pressure=internal pressure of material container (Pi)−external pressure of material container (Po)
[0048] Pc: Limit difference in pressure=Difference in pressure between internal pressure of material container (Pi) and external pressure of material container (Po) at limit where the flowable material flows down from the orifice by its own weight.
[0049] Furthermore, in the above, the limit difference in pressure can be obtained from the relation between target material, orifice diameter and supply pipe diameter.
[0050] As described above, by controlling the difference in pressure based on the (Equation 4), the production process of monodisperse particle according to this invention allows to facilitate to flow the flowable material as much as possible through the supply pipe, to continuously and efficiently supply the flowable material, and then to enhance the productivity of monodisperse particle of uniform particle size (particle diameter) to its limit.
[0051] In the above, when the difference in pressure P between internal pressure of the material container (Pi) and external pressure of the material container (Po) is 0, the flowable material can not be facilitated to be supplied through the supply pipe.
[0052] On the other hand, when the difference in pressure P between internal pressure of the material container (Pi) and external pressure of the material container (Po) exceeds the limit difference in pressure Pc, the flowable material flows down from the orifice by its weight and then the production control becomes difficult.
[0053] In addition, it is preferable that the recovery part is located at the lower of the orifice plate, and lets the liquid drop ejected naturally fall. This allows to highly precisely and efficiently produce monodisperse particle under gravity without variation.
[0054] The production process of monodisperse particle according to this invention allows to highly precisely and easily control the diameter of monodisperse particle recovered depending on the diameter of the orifice.
[0055] In that case, the production process of monodisperse particle according to this invention allows to control the diameter of monodisperse particle to the size of 0.9 to 1.1 times of the orifice diameter, and this allows to produce the monodisperse particle of small standard deviation by simple control procedure.
[0056] By substantially making the recovery part have inert atmosphere, it is possible to prevent oxidation of the obtained monodisperse particle and to stabilize its quality.
[0057] By putting the flowable material to molten metal melted in the material container having heating device, and carrying out recovery in the recovery part by cooling with cooling speed above the critical cooling speed, it is possible to change the component particles to amorphous and then to metallic glass particle.
[0058] Further, it is preferable that the cylinder rod is provided with precision positioning means. This allows to easily, accurately control and manage of the diameter of the obtained monodisperse particle.
[0059] Further, it is preferable that the inner surface of the orifice that the flowable material passes is made of material that has poor wetability with flowable material, especially molten metal. This allows to enhance the uniformity of each component particle of the obtained monodisperse particle.
[0060] In addition, as will be described later, by regulating the diameter of the orifice, dimension of clearance between the cylinder rod and its receiving part, the flowable material and retention container for flowable material, especially wetability (material and finishing state of the surface) between molten metal and container for molten metal, and additionally, gas pressure of the inert gas in the retention container for flowable material, operating frequency and frequency wave form and displacement of the piezoelectric actuator, the flowable material, especially temperature and surface tension of the molten metal, it is possible to control the particle diameter of producing monodisperse particle.
[0061] It is suitable that the standard deviation of the monodisperse particle produced by the production process according to the invention described above is below 2 &mgr;m. This allows to laminate other plane body with close contact on the plane body on which the particles in 100 to 300 &mgr;m are arranged in plane, two dimensionally. This function, for example when applying the monodisperse particle to the BGA (Ball Grid Array), has an effect of production efficiency that 200 electrodes can be simultaneously connected without generating joint defective etc.
[0062] In this case, if the standard deviation exceeds 2 &mgr;m, it is difficult to laminate other plane body with close contact on the plane body on which the particles in 100 to 300 &mgr;m are arranged in plane, two dimensionally, in this sense, it is difficult to apply to the area in which uniformity of the component particle diameter is particularly important, in this point, there are applications in which it can not be applied as monodisperse particle, therefore, it can not be widely used and inconvenient.
[0063] Further, the monodisperse particle according to the invention, which is produced by the production process according to the invention, is obtained by controlling the diameter of each particle composing monodisperse particle to 0.9 to 1.1 times in size of the orifice diameter. This allows to apply to the application as monodisperse particle without requiring classification operation. At the same time, This allows to prevent the situation in which standard deviation becomes excessive to the ratio of standard deviation/diameter, even when obtaining monodisperse particle of which the average diameter of component particle is small.
[0064] For the monodisperse particle produced by the production process according to the invention described above, it is preferable that variation in diameter of each particle composing monodisperse particle is within ±10%.
[0065] This allows to apply to the applications as monodisperse particle particularly without classification operation of the recovered particles. From this point, it is more suitable that variation in diameter of each particle composing monodisperse particle is within ±2%.
[0066] Further, it is preferable that the monodisperse particle produced by the production process according to, the invention described above has standard deviation of below 5 &mgr;m, sphericity of below 2.5%.
[0067] In here, if the standard deviation exceeds 5 &mgr;m, the flowability lowers and the filling density becomes small as well as variation in the component particles becomes excessive, and become nonuniform as aggregation, as a result, there are applications in which it can not be applied as monodisperse particle, therefore, it can not be widely used and inconvenient. As a result, there is inconvenience that classification operation is separately required. Further, if the sphericity exceeds 2.5%, the component particles become irregular, and there are applications in which it can not be applied, therefore, it can not be widely used and inconvenient.
[0068] Further, it is preferable that the monodisperse particle produced by the production process according to the invention described above has standard deviation of below 5 &mgr;m, sphericity of below 2.5%.
[0069] As such monodisperse particle is obtained as monodisperse particle controlled such that the standard deviation is below 5 &mgr;m, and the sphericity is below 2.5% by ejecting flowable material per unit amount and directly recovering, no classification operation is required especially for enhancing uniformity with comb etc. and efficient production can be performed. Being directly recovered and obtained means that monodisperse particle having certain properties is obtained without performing classification operation by comb etc.
[0070] In here, if the standard deviation exceeds 5 &mgr;m, variation in the component particles becomes excessive, as a result, there are applications in which it can not be applied as monodisperse particle, therefore, it can not be widely used and inconvenient, and further, if the sphericity exceeds 2.5%, the component particles become irregular, and there are applications in which it can not be applied, therefore, it can not be widely used and inconvenient.
[0071] Further, it is preferable that the monodisperse particle produced by the production process according to the invention described above, which is obtained by ejecting flowable material per unit amount and directly recovering, has standard deviation of below 5 &mgr;m, sphericity of below 2.5%, and the particle diameter of the component particle is controlled at a certain value.
[0072] As such monodisperse particle is obtained as monodisperse particle controlled such that the standard deviation is below 5 &mgr;m, and the sphericity is below 2.5% by ejecting flowable material per unit amount and directly recovering and the particle diameter of the component particle composing the obtained monodisperse particle is controlled at a certain value, it is possible to cheaply, efficiently produce monodisperse particle composed of component particles of particle diameter corresponding to the application or versatility field of the monodisperse particle.
[0073] For the monodisperse particle according to the invention described above, it is more preferable that the standard deviation is within 1% of the average diameter of the component particles composing the monodisperse particle. This allows to generally realize uniformly arranged particle aggregation, enhance the flowability and increase the filling density, equalize each particle property and enhance reliability. In particular, this allows to easily arrange in a certain dimensional zone when allotting the component particles while closely contacting, and to laminate other plane body with close contact on the plane body on which the component particles are arranged in plane, two dimensionally even when the average particle diameter of the component particles are less than 100 &mgr;m, and to has an effect of production efficiency that 200 electrodes can be simultaneously connected without generating joint defective etc., for example, when applying the monodisperse particle to the BGA (Ball Grid Array).
BRIEF DESCRIPTION OF THE DRAWINGS[0074] FIG. 1 is a schematic side view showing one example of apparatus arrangement in production apparatus of monodisperse particles according to this invention;
[0075] FIG. 2 is a schematic cross-sectional view showing detail of B part in FIG. 1;
[0076] FIG. 3 is a cross-sectional view showing a example of shape of orifice in production apparatus of monodisperse particles according to this invention;
[0077] FIG. 4 is a general schematic drawing of pressure management system applied to production apparatus of monodisperse particles according to this invention;
[0078] FIG. 5 is a schematic cross-sectional view showing other example of apparatus arrangement in production apparatus of monodisperse particles according to this invention;
[0079] FIG. 6 is a cross-sectional view showing shape of orifice of production apparatus of monodisperse particles according to one example of this invention;
[0080] FIG. 7 is a schematic side view showing overall arrangement of production apparatus of monodisperse particles according to other embodiment of this invention;
[0081] FIG. 8 is a schematic cross-sectional view showing detailed arrangement of cylinder rod position adjusting mechanism part B3 and monodisperse particle forming part B4 in FIG. 7;
[0082] FIG. 9 is an enlarged cross-sectional view of heater which is a primary part of monodisperse particle forming part B4 in FIG. 7;
[0083] FIG. 10 is an enlarged cross-sectional view of nozzle part which is a primary part of monodisperse particle forming part B4 in FIG. 7;
[0084] FIG. 11 is an enlarged schematic description drawing of nozzle part which is a primary part of monodisperse particle forming part B4 in FIG. 7 as well;
[0085] FIG. 12 is an enlarged cross-sectional view of nozzle part which is a primary part of monodisperse particle forming part B4 of production apparatus of monodisperse particles according to other embodiment of this invention;
[0086] FIG. 13 is a SEM photograph as a substitute for drawing, showing particle structure of monodisperse particle obtained in example;
[0087] FIG. 14 is a graph of monodisperse particle shown in FIG. 13;
[0088] FIG. 15 is a pulse wave form in one example of this invention;
[0089] FIG. 16 is observation photographs by scanning electron microscope, showing shape of &bgr;-TPC dried particles obtained by apparatus of FIG. 1;
[0090] FIG. 17 is graphs showing particle diameter distribution of &bgr;-TPC dried particles obtained by apparatus of FIG. 1;
[0091] FIG. 18 is observation photographs by scanning electron microscope, showing shape of &bgr;-TPC dried particles obtained by apparatus of FIG. 5;
[0092] FIG. 19 is graphs showing particle diameter distribution of &bgr;-TPC dried particles obtained by apparatus of FIG. 5;
[0093] FIG. 20 is SEM photographs (a) and (b) as substitute for drawing, showing particle structure of monodisperse particle, and both are obtained in examples;
[0094] FIG. 21 is a graph of particle diameter distribution of monodisperse particle shown in FIG. 20(b);
[0095] FIG. 22 is a graph showing results of XRD analysis of monodisperse particle shown in FIG. 20(b);
[0096] FIG. 23 is a SEM photograph as a substitute for drawing, showing particle structure of monodisperse particle obtained in example;
[0097] FIG. 24 is a graph of particle diameter distribution of monodisperse particle shown in FIG. 23;
[0098] FIG. 25 is a SEM photograph as a substitute for drawing, showing particle structure of monodisperse particle obtained in example; and
[0099] FIG. 26 is a graph of particle diameter distribution of monodisperse particle shown in FIG. 25.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS[0100] The embodiments according to the invention are shown below.
[0101] Embodiment 1
[0102] FIG. 1 is a schematic side view showing one example of the production apparatus of monodisperse particle according to the invention.
[0103] This embodiment relates to the case that the production apparatus of monodisperse particle according to the invention is constituted as a production apparatus of ceramics spherical monodisperse particle, and uses slurry containing raw material ceramic powder as flowable material.
[0104] In FIG. 1, A is a means to transfer a part of ceramics spherical monodisperse particle forming portion (from piezoelectric actuator to diaphram, hereinafter, this is called B1 block). In other words, this is a lift for inspecting and charging material to move and separate from slurry retention chamber etc. (hereinafter, this is called B2 block) as storage container for flowable material described later to the upper, consisting of motor-powered screw jack.
[0105] B is primary portion of the apparatus, that is, monodisperse particle forming portion. C is a recovery part for finished monodisperse particle. D is a vacuum suction mechanism used when replacing peripheral of the monodisperse particle forming portion B and recovery part C with inert gas. E is a cooling water circulator to supply cooling water to cooling mechanism provided to prevent overheat the piezoelectric actuator in the monodisperse particle forming portion B. F is a power box for entire apparatus, G is a operation panel to operate the entire apparatus.
[0106] FIG. 2 is a schematic cross-sectional view showing detailed arrangement of the above monodisperse particle forming portion B. The monodisperse particle forming portion B is largely divided into B1 block and B2 lock as described before. The B1 block consists of piezoelectric actuator 12, holder block 39 connecting the piezoelectric actuator 12 and the transmission rod 14, diaphram 15 installed on the top end of the transmission rod 14, and base flange 13 holding the holding portion 15a etc. of the diaphram 15.
[0107] Further, the B2 block consists of slurry retaining part 21a as a storage container for floawable material for retaining slurry containing raw material ceramic powder and slurry retaining part 21b as a container for material, nozzle 22 located at the lower of the slurry retaining part 21a, orifice plate 23 located at the top of the nozzle 22 and having more than one orifice, inert gas supply pipe for supplying inert gas to pressurize to the slurry retaining part 21b. Between the slurry retaining part 21a and the slurry retaining part 21b, relatively thin supply pipe 21c is provided. Further, sealing member 16 is adhered to the lower of the holding portion 15a of the diaphram, constituted to be connected air-tightly between the B2 block and the B1 block. In the slurry retaining part 21a and the slurry retaining part 21b, means to agitate slurry, for example, agitating bar may be installed.
[0108] At the lower of the slurry retaining part 21a, adverse cone part of the nozzle 22 provided supplies the slurry retained in the nozzle 22 to further downward orifice plate. The orifice plate 23 is held by the pressing member 23a. The material constituting the orifice plate 23 is determined depending on the type of the ceramic produced. For example, by appropriately selecting the component materials of the orifice plate 23, wetability with slurry is adjusted.
[0109] Further, when the wetability between the orifice and slurry is very good and the slurry flows out through the orifice, the wetability is lowered not only by appropriately selecting the component materials of the orifice plate 23 but also by applying silicon grease etc. on the surface of the orifice.
[0110] For the shape of the orifice, a schematic cross-sectional view of its embodiment is shown in FIG. 3. FIG. 3(a) shows a normal orifice. While, in FIG. 3(b), protrusion 22a is provided on the nozzle 22 of the orifice portion. In this application, it is more preferable to apply the shape in FIG. 3(b) for preventing the slurry from flowing out through the surface of orifice.
[0111] Further, the diameter of the orifice can be appropriately determined depending on the particle diameter of the particles. It is preferable that the diameter is in the range of nearly 30 to 500 &mgr;m, more preferably in the range of nearly 50 to 300 &mgr;m.
[0112] In the production apparatus of monodisperse particle according to the embodiment, relation between this orifice diameter &dgr;o and the supply pipe diameter &dgr;f of the supply pipe 21c is set so that the supply pipe diameter &dgr;f is greater than the orifice diameter &dgr;o of the orifice. That is, the orifice diameter is set to be in the range of nearly 30 to 500 &mgr;m, more preferably in the range of nearly 50 to 300 &mgr;m, and further, the supply pipe diameter &dgr;f is set to be in the range of 100 to 900 &mgr;m and greater than the orifice diameter &dgr;o.
[0113] For the piezoelectric actuator 12, laminar type piezoelectric element is preferably used. Further, the piezoelectric actuator 12 is connected to function generator, not shown, for generating rectangular wave form of a certain frequency, and power amplifier, not shown, for amplifying the above rectangular waveform. And applying the rectangular waveform generated and amplified by these allows to generate displacement of certain frequency.
[0114] The displacement of the piezoelectric actuator 12 is transmitted to the diaphram 15 through the transmission rod 14 connected thereto. The diaphram 15 transmits the displacement to the displacement to the slurry retained in the slurry retention part 21a. This transmission of the displacement allows to eject spherodized slurry drop of particle diameter nearly similar to the orifice diameter. In this case, the frequency of the piezoelectric actuator 12 is not specifically limited, and can be appropriately selected depending on the material of the ceramics spherical monodisperse particle produced and the desired producing speed.
[0115] At the lower of the orifice plate 23, recovery part C is provided for capturing the slurry ejected. This recovery part C consists of drying furnace 42 having falling tube 40 adjustable to inert gas atmosphere and heater 41 heating this from the outside, gate valve 43, recovery box 44 recovering the product (ceramics spherical monodisperse particle) dried by the heater 41. It is preferable that for example the heater 41 is induction heater, and operator can regulate the temperature of the inside of the drying furnace 42 to the desired temperature. The temperature of the inside of the drying furnace 42 is regulated and maintained at the temperature so that the slurry drop falling in the falling tube 40 is sufficiently dried. Further, it is important for sufficient dry that the furnace length of the drying furnace 42 is sufficient. Further, it is possible to facilitate drying by installing two of heater 41 in upward and downward of the outside of the falling tube 40.
[0116] The vacuum suction mechanism D used when replacing peripheral of the recovery part C and monodisperse particle forming part B with inert gas is connected to the recovery part C, as described before. In preparing stage of apparatus powering, with opening the gate valve 42, the vacuum suction mechanism D discharge around the recovery part C and monodisperse particle forming part B. After that, inert gas such as helium gas is supplied from supply source of inert gas, not shown, as inert gas atmosphere. This inert gas atmosphere allows to prevent oxidation of the ceramics spherical monodisperse particle and enhance the quality of the product.
[0117] In the following, the process when producing the ceramics spherical monodisperse particle using apparatus having the above arrangement is described in order.
[0118] At first, slurry containing raw material ceramic powder is prepared. As a raw material ceramic powder, shattered powder etc obtained by shattering ceramics containing the desired material is used. The slurry is prepared mixing this powder and dispersant. The type of dispersant and adding amount are appropriately selected depending on the material property of the powder ingredient. In other words, that is selected so that the viscosity of the slurry and dispersion stability is proper. Further, in order to maximize these properties in the slurry, additives such as binder other than dispersant may be appropriately added.
[0119] The next is to carry out vacuum de-foaming to remove foams in the slurry. After that, the process is moved to the slurry filling process to the production apparatus of monodisperse particle.
[0120] The B1 block of the ceramics spherical monodisperse particle forming part B is lifted and separated from B2 block by the lifter A. In this state, the slurry is filled in the slurry retention part 21b. The slurry flows into the slurry retention part 21a, and reaches to the nozzle 22. While, the cooling water is supplied to the piezoelectric actuator 12 from the cooling water circulator E to suppress the increase in temperature. The air around the ceramics spherical monodisperse particle forming part B and in the recovery part C is discharged by the vacuum suction mechanism D, thereafter, the inert gas is supplied from the inert gas source not shown. This pressure is same as atmospheric pressure, or little higher than atmospheric pressure.
[0121] After the slurry is filled into the entirety, assemble the separated block B1 into the previous position, start the operation of the apparatus. In the function generator, the rectangular waveform of the determined frequency is generated, and amplified by the power amplifier, and then applied to the piezoelectric actuator 12. The shape and frequency of the rectangular waveform generated are appropriately selected depending on the viscosity of the slurry etc.
[0122] The piezoelectric actuator 12 generates vibration with determined frequency and determined amplitude, which is transmitted to the diaphram 15 through the transmission rod 14. The diaphram 15 vibrates with pulse of the same frequency as that of the piezoelectric actuator 12, and generates pulse pressure wave on the slurry contacting thereto. The slurry in the slurry retention part 21a is ejected from the orifice on the orifice plate 23 as slurry drop one time per one period of the pulse pressure wave generated as described above.
[0123] The slurry drops freely fall in the drying furnace 42 in the recovery part C, and are spheroidized by surface tension during its falling. In addition, operator appropriately regulates the heater 41, and the inside of the drying, furnace 42 is maintained at determined temperature. The temperature at this time is appropriately determined so that the liquid ingredient is completely dried and removed. The ceramics spherical monodisperse particles completely dried as above are recovered in the recovery box 44. As described above, ceramics spherical monodisperse particles with the particle diameter generally corresponding to the orifice diameter are produced.
[0124] In the production apparatus of monodisperse particles according to the embodiment as above, as described before, the relation between the orifice diameter &dgr;o and the supply pipe diameter &dgr;f of the supply pipe 21c is set such that the supply pipe diameter &dgr;f of the supply pipe is greater than the orifice diameter &dgr;o of the orifice, as a result, the slurry smoothly flows from the inside of slurry retention part 21b to the slurry retention part 21a, and this allows to complete conditions that the same amount of the slurry in the slurry retention part 21a is held at any time.
[0125] In other words, the slurry in the slurry retention part 21a is ejected as slurry drop from the orifice on the orifice plate 23, the slurry usually smoothly flows in and out between the slurry retention part 21a and 21b depending on the vibration of the diaphram 15. In this case, however, if the slurry by its own weight falls toward the recovery part C, it is difficult to efficiently and continuously produce the ceramics spherical monodisperse particles. Accordingly, such a falling of slurry by its own weight is required to be prevented. On the other hand, as described before, usually the slurry must be stably supplied from the slurry retention part b to the slurry retention part 21a. Unless the amount of slurry in the slurry retention part 21a is maintained at constant, high quality ceramics monodisperse particles of uniform particle diameter can not be obtained.
[0126] By the above reasons, in the production process of ceramics monodisperse particles using the production apparatus of monodisperse particles according to the embodiment, the internal pressure of the slurry retention part b and its external pressure, the pressure of the recovery part C, are controlled as follows.
[0127] FIG. 4 shows a conceptual figure of the pressure control system applied to the production apparatus of monodisperse particles according to the embodiment. As shown in FIG. 4, the pressure in the slurry retention part 21b, that is, the pressure applied on the slurry liquid face in the slurry retention part b and the pressure out of the slurry retention part b, that is, the pressure in the recovery part C are respectively controlled. Such a control is carried out at least in the operating process so that the (Equation 4) is satisfied.
0≦P<Pc (Equation 4)
[0128] P: Difference in pressure=Internal pressure (Pi) of the material container (Slurry retention part b)−External pressure (Po) of the material container (Slurry retention part b)
[0129] Pc: Limit difference in pressure=Difference in pressure between limit internal pressure (Pi) of the material container (Slurry retention part b) and limit external pressure (Po) of the material container (Slurry retention part b) when the slurry flows down from the orifice by its own weight.
[0130] In this case, the limit difference in pressure is experimentally obtained according to the relation between quality of the slurry, orifice diameter and supply pipe diameter.
[0131] The production process of monodisperse particles according to the invention, as described above, controls the internal and external pressure of the slurry retention part b, therefore, this allows to facilitate the supply of the slurry through the supply pipe 21c, to supply the slurry continuously and efficiently, and to mass-produce monodisperse particles of uniform particle size (particle diameter) stably.
[0132] In the above, when the difference in pressure between the internal pressure (Pi) of the slurry retention part b and external pressure (Po) of the slurry retention part b is less than 0, this is a factor to obstruct the supply through the supply pipe 21c, whereas, when the difference in pressure between the internal pressure (Pi) of the slurry retention part b and external pressure (Po) of the slurry retention part exceeds the limit difference in pressure, the slurry flows down from the orifice by its own weight, therefore, it is difficult to control production.
[0133] Embodiment 2
[0134] The embodiment 2 according to the invention is shown as below. This embodiment also relates to the case that the production apparatus of monodisperse particle according to the invention is constituted as a production apparatus of ceramics spherical monodisperse particle, and uses slurry containing raw material ceramic powder as flowable material. As reference, the parts overlapping the embodiment 1 described above are omitted and only different parts are explained. In the embodiment 1, the liquid ingredient of the slurry drop ejected from the orifice was removed by heating and drying. Whereas, this embodiment employs the so-called “freeze dry process” that slowly removes humidity by freezing and drying.
[0135] FIG. 5 is a schematic side view showing one example of apparatus arrangement of production apparatus of monodisperse particles according to the embodiment 2 of this invention. The cooling part 45 full of liquid nitrogen is provided at the lower of the orifice. The cooling part 45 is of removable structure when in preparing working, and reduction in pressure sublime working described later before the operation of the apparatus. The distance from the orifice to the liquid nitrogen in the cooling part 45 is not particularly limited, provided that it is sufficient distance to spheroidize the slurry drop ejected from the orifice.
[0136] Then, the process in which ceramics spherical monodisperse particles are produced using the above apparatus will be described. The slurry drop falls straight down to the lower of the orifice, and it is spheroidized by surface tension during falling. And it is trapped in the liquid nitrogen in the cooling part 45. After that, the cooling part 45 is taken out from the apparatus, and reduced in pressure so that the liquid phase does not appear. And then, solid phase is sublimed and ceramics spherical monodisperse particles are obtained by slowly heating.
[0137] According to the invention, the slurry drops ejected from the orifice fall straight down without splashing widely. Accordingly, it is sufficient that the cooling part 45 is small. In addition, it is sufficient that the liquid nitrogen used is of small amount. Accordingly, this allows to be simpler in apparatus arrangement than the embodiment 1, and to be compact.
[0138] Embodiment 3
[0139] FIG. 7 is a schematic side view showing the overall arrangement of the production apparatus (hereinafter, may be called just the apparatus) 10 for monodisperse particles according to the embodiment 3 of the invention.
[0140] This embodiment relates to the case that the production apparatus of monodisperse particle according to the invention is constituted as a production apparatus of metallic spherical monodisperse particle, and uses liquid metal as flowable material.
[0141] In FIG. 7, FIG. 8, the lifter A to move upward and separate the cylinder rod position regulating mechanism part B3 and a part of the monodisperse particle forming part B4 (a part from the piezoelectric actuator to nozzle part) for inspection, consists of motor-powered screw jack as in each of the above embodiments. Further, the cylinder rod position regulating mechanism part B3 is provided for making fine adjustment of the initial position of the cylinder rod in the monodisperse particle forming part B4 as described later, as well F is a high-frequency induction heater to supply power to the high-frequency heater of the monodisperse particle forming part B4.
[0142] FIG. 8 is a schematic cross-sectional view showing detailed arrangement of the cylinder rod position regulating mechanism part B3 and the monodisperse particle forming part B4 as described above, and FIG. 9, FIG. 10 are respectively enlarged cross-sectional views of the heater and nozzle part that are primary part of the above monodisperse particle forming part B4.
[0143] At first, the cylinder rod position regulating mechanism part B3, as shown in FIG. 8, consists of piezoelectric actuator 12 of the monodisperse particle forming part, holder block 39, adapter 55 holding transmission rod 14 and cylinder rod 14a, and elevating base 31 holding the adapter 55 and inserted through two screw shafts 13a fixed to base flange 13, and two guide shafts fixed to the base flange 13 as well.
[0144] This elevating base 31 is movable up and down through worm gear unit 13C along the screw shaft 13a and guide shaft 13b by turning the handle 13d located on one end thereof, as described later, is constituted so that the initial position of the cylinder rod can be finely adjusted with accuracy of nearly 0.1 mm. In addition, reference numeral 33 denotes a dial gage for reading the position.
[0145] The next, the general arrangement of the monodisperse particle forming part B4 will be described. In FIG. 8, 12 shows piezoelectric actuator retained to the adapter 55 of the cylinder rod position regulating mechanism part B3, and 14, transmission rod fixed to the piezoelectric actuator 12 by holder block 39, and the top end of the transmission rod 14 forms cylinder rod 14a fitted into the nozzle part 25 as described later. In addition, the middle part of the transmission rod 14 (a part between connecting portion to the piezoelectric actuator 12, and base flange 13) is covered with extendable bellows 53 to prevent ingress of foreign matters.
[0146] On the above flange base, raw material supply port 60a in which raw material supply pipe 60 is inserted and inserting port 61 for thermocouple 62 for measuring temperature are provided. The nozzle holder 46 as described later is fixed under the above base flange 13, and scrucible 26 as also described later and the nozzle part 25 are held to this nozzle holder 46. The space between from under the above base flange 13 to the nozzle 25 is also a part to transfer the raw material supplied from the raw material supply pipe 60 to the heater 20, as described later, located downward therefrom.
[0147] The above heater 20, as the details are shown in FIG. 9, consists of carbon susceptor 20a made of carbon, which is heating element, separated with space 28 outside of the crystal scrucible 26 together with nozzle part 25 (these are constituted to be removable from the inside of heater 20 as described later) holding heated and melted raw material, insulator 20b located to surround these, protecting tube 20c outside thereof, and work coil 20d for high-frequency heating further outside thereof. In addition, the lid 21 for insulating is provided on the upper of the heater 20.
[0148] The above heater 20 excites the work coil 20d by the excited current supplied from the high-frequency induction heater H shown in FIG. 7, heats the carbon composing the carbon susceptor 20a by high-frequency generating therefrom, and heats the scrucible 26 in the susceptor 20a and the charged raw material therein by this heat, therefore, has excellence in uniform heating property, and additionally, has the advantage that it is possible to relatively easily obtain high temperature up to nearly 1000° C. Further, this heater 20 can work effectively even when using material that in not heated even in directly applying the high-frequency.
[0149] The nozzle part 25, of which outer region is supported by the above scrucible 26, is set in the scrucible 26 (lower therein), is provided with adverse cone shaped recess 25a for collecting the heated and melted raw material to the center of the nozzle part 25, and more than one nozzles 25b for transferring the heated and melted raw material to the orifice part described later. This nozzle 25b communicates in cavity 25C, which is a space at the lower of the cylinder rod 14a, as storage container for flowable material, and the cavity 25C becomes substantial material melting retention part. The heated and melted raw material supplied is stored in the above cavity 25C through the nozzle 25b.
[0150] On the lower face of the nozzle 25, the orifice plate 23 provided with many orifices for ejecting metallic glass is mounted by pressing member 23a. For the material constituting this orifice plate 23, optimum material may be selected depending on the property of the target flowable material, particularly the type of the metallic glass raw material.
[0151] In the production apparatus of monodisperse particle according to the embodiment, the diameter of the orifice is set based on the guide shown in the below.
[0152] In other words, as shown in FIG. 11, it is constituted such that the space area Af between inside of the nozzle part 25 and the cylinder rod 14a, and the cross-section Ao of the orifice satisfy the (Equation 3).
Af>Ao (Equation 3)
[0153] This allows to facilitate the supply of the melting material to the cavity 25c through the space between the inside of the nozzle part 25 and the cylinder rod 14a, performs the supply smoothly and allows continuous and stable production of the monodisperse particle.
[0154] The diameter of the orifice can be appropriately selected with reference to the particle diameter of monodisperse particle intended for production while satisfying the above conditions, however, for example, it is better to be 30 &mgr;m to 500 &mgr;m, more preferably, 50 &mgr;m to 300 &mgr;m.
[0155] The orifices for ejecting metallic glass raw material provided on the orifice plate 23 are removable. This allows to appropriately set the orifice diameter of the orifice removed or installed on the orifice plate 23 based on the particle diameter produced and the above guide, and to high-accurately and easily control the diameter of the recovered monodisperse particles.
[0156] The upper of the nozzle part 25 extends to the scrucible 26 provided with the thermocouple 62 for measuring temperature, as a whole, forms raw material melting part-cum-liquid metal retainer 25d as material container which melts raw material supplied as described later and store the melted raw material. This lower of the raw material melting part-cum-liquid metal retainer 25d communicates to the cavity 25C further downward of the cylinder rod 14a being inserted into the nozzle part 5, through the nozzle 25b in the nozzle part 25.
[0157] Upward of the scrucible 26, over the raw material supply port 60a, reflector 65 is provided for maintaining temperature in the scrucible 26 and preventing discharge of heat to the outside. This reflector 65 has metal thin plates on the front and back, which are connected with wire shaped connecting member. In addition, the reflector 65 has hole to insert the transmission rod 14 and cylinder rod 14a, and hole to for which the raw material supplied from the raw material supplying part 60 passes.
[0158] These scrucible 26, nozzle part 25 and reflector 65 etc. are engaged to the nozzle holder 46 provided with raw material supply port 60a and thermocouple inserting port 61 described before, and this nozzle holder 46 is engaged to the base flange 13 described before, and these are constituted so that these are integrally lifted from the inside of the heater 20 and taken out by the lifter A when inspecting.
[0159] While, the downward of the orifice plate 23 for the orifice 25, recovery part (C in FIG. 7) for capturing the ejected monodisperse particles. This recovery part C has sample tray 40 for capturing initial ejecting sample at its up-most, and its lower part is connected to recovery tube 41 for which inert gas flow is supplied, gate valve 42, recovery box 43 for product (component particle for monodisperse particle, in particular metallic glass particle) cooled in the recovery tube 41 after ejected.
[0160] The recovery part consisting of these parts is connected to sphericity suction mechanism part D used when surrounding of this recovery part C and monodisperse particle forming part B4 is replaced with inert gas, and on the preparing stage before operating the apparatus, with opening the gate valve 42 as described before, the vacuum suction mechanism part D discharges inside of the recovery part C and around the monodisperse particle forming part B4, after completion of discharging, inert gas such as helium gas is supplied at determined pressure from the supply source, and then all the passages for the metallic glass sphere are filled with inert gas.
[0161] In addition, the above sample tray 40 is provided for receiving the metallic glass particles ejected at an early stage of the operation of the apparatus, and observing and checking the state, for example by using metal microscope. In this state, they are not cooled sufficiently, therefore, condensing and deforming occurs, and then complete shaped metallic glass particle sphere is not obtained, however, it is possible to check the possibility for production conditions. When the check of the possibility for production conditions is terminated the sample tray 40 is constituted to be evacuated from the main path.
[0162] As piezoelectric actuator 12 used for monodisperse particle forming part B4, laminated piezoelectric element can be suitably used. This piezoelectric actuator 12 is connected to function generator generating rectangular wave of determined frequency (for example, nearly 10 Hz to 10 KHz), and power amplifier (either of them is not shown) amplifying the above rectangular wave, and by applying the rectangular wave generated and amplified by these, displacement of the determined frequency is generated.
[0163] The displacement of the piezoelectric actuator 12 is transmitted to the cylinder rod 14a through the transmission rod 14 fixed to the above piezoelectric actuator 12. The cylinder rod 14a is inserted into the nozzle part 25, and by transmitting the displacement to the raw material heated and melted, and stored in the cavity 25C of this nozzle part 25, the above melted raw material is ejected from the orifice at pulse pressure corresponding to the displacement, therefore, fine metallic glass particle can be produced.
[0164] In addition, the above piezoelectric actuator 12 is installed by actuator holder fixed by four retaining screws (not shown) threaded into the four screw taps on the side surface in the holder block 39. Additionally, the piezoelectric actuator 12 and the transmission rod 14 are connected by providing the piezoelectric actuator 12 between the actuator holder and the transmission rod 14, and fixing these actuator holder and transmission rod 14 with bolts and nuts (not shown).
[0165] In this way, integration of the piezoelectric actuator 12 and the transmission rod 14 allows to correctly transmit the movement of piezoelectric actuator 12 to the cylinder rod 14a, accordingly, to vibrate the cylinder rod 14a depending on the displacement transmitted. In addition, the arrangement using this piezoelectric actuator 12 allows correct displacement control and high-speed drive (possible to follow up high-frequency) of the cylinder 14a and control at any waveform.
[0166] In general, for piezoelectric element, the piezoelectric function loses as it gets higher temperature, accordingly, it is required to be cooled. For this reason, the apparatus 10 according to the embodiment uses the cooling water circulator D, and installs the water cooling at the part of the apparatus unit (the periphery of the piezoelectric actuator 12 and the holder block 39 and so on), and then maintains the piezoelectric actuator 12 below its operating limit temperature.
[0167] In addition, upward of the heater 20, inert gas introduction pipe 35 connected to the supply source, not shown, is located, regulates the atmosphere in the scrucible 26, separately from regulating the atmosphere of whole monodisperse particle forming part B4. This is to control the supply of the inert gas from the above inert gas introduction pipe 35 for balancing between the pulse pressure wave applied to the melted raw material corresponding to the displacement transmitted to the cylinder rod 14a, therefore, to control the gas pressure (and gas pressure applied to the cavity 25) in the scrucible 26.
[0168] The next is to explain the process in order when producing the metallic glass spherical monodisperse particle using apparatus having the above arrangement.
[0169] At first, the raw material for metallic glass sphere produced is charged into the scrucible 26 from the raw material supply pipe 60, and the raw material is melted by turning on the power of the apparatus. The melted raw material (liquid metal) is stored on the nozzle part 25 at the bottom of the scrucible 26, and a part of it passes through the nozzle 25b, also fills the cavity 25C by moving the cylinder rod 14a up and down a few times. In addition, after the raw material is melted, it is possible that the heater 20 is kept warm.
[0170] While, cooling water supplied from the cooling water circulator E is kept to be circulating in the holder block 39 etc. to prevent temperature of the piezoelectric actuator 12 from rising.
[0171] In the production process of monodisperse particle according to the embodiment, pressure control similar to that in the previous embodiment 1 is carried out. That is, as shown in FIG. 4, the pressure in the material container, scrucible 26, that is, the pressure applied on the liquid surface in the scrucible 26, and external pressure of the scrucible 26, that is, the pressure in the recovery part C are respectively measured and controlled. Such a control is performed at least in the operating process so that the (Equation 4) is satisfied.
0≦P<PC (Equation 4)
[0172] P: Difference in pressure=Internal pressure (Pi) of the material container (Scrucible 26)−External pressure (Po) of the material container (Scrucible 26)
[0173] Pc: Limit difference in pressure=Difference in pressure between limit internal pressure (Pi) of the material container (Scrucible 26) and limit external pressure (Po) of the material container (Scrucible 26) when the slurry flows down from the orifice by its own weight
[0174] In this case, the limit difference in pressure is experimentally obtained according to the relation between quality of the material liquid, orifice cross-section Ao, space area Af between inside of the nozzle part 25 and the cylinder rod 14a.
[0175] The production process of monodisperse particles according to the invention, as described above, controls the internal and external pressure of the scrucible 26, therefore, this allows to facilitate the supply of the material liquid through the space between inside of the nozzle part 25 and the cylinder rod 14a, to supply the material liquid continuously and efficiently, and to mass-produce monodisperse particles of uniform particle size (particle diameter) stably.
[0176] In the above, when the difference in pressure between the internal pressure (Pi) of the scrucible 26 and external pressure (Po) of the scrucible 26 is less than 0, this is a factor to obstruct the liquid material through the space between inside of the nozzle part 25 and the cylinder rod 14a. Whereas, when the difference in pressure between the internal pressure (Pi) of the scrucible 26 and external pressure (Po) of the scrucible 26 exceeds the limit difference in pressure, the material liquid flows down from the orifice by its own weight, therefore, it is difficult to control production.
[0177] As described above, by discharging air around the monodisperse particle forming part C and of the recovery part C using the vacuum suction mechanism part D, and supplying inert gas by the pressure control system shown in FIG. A, the determined pressure control is performed.
[0178] Then, the above function generator generates the rectangular waves of determined frequency, which are applied to the piezoelectric actuator 12 after amplified by power amplifier, and generates the vibration of determined frequency and amplitude, vibrates the cylinder rod 14a with pulse of the same frequency as above through the transmission rod 14 substantially integral with the piezoelectric actuator 12, generates pulse pressure waves to molten metal in the cavity 25C contacting the cylinder rod 14a.
[0179] This allows the cylinder rod 14a to displace through the transmission rod 14 and eject the liquid as liquid drop in the cavity 25C from the orifice on the orifice plate 23 when the piezoelectric actuator 12 displaces downward more than determined displacement amount. This ejection is carried out one time per one period of the pulse pressure wave.
[0180] The liquid drops ejected in this way, of which cooling speed is optimally controlled by the inert gas atmosphere in the recovery part C, spheroidize to generally sphericity while falling in the recovery part C, are recovered as metallic glass sphere. In this way, metallic glass sphere having diameter generally close to diameter of the orifice, spherodized to generally sphericity can be obtained. The metallic glass sphere obtained in this way has very little variation of particle size (particle diameter) variation.
[0181] The apparatus 10 allows to eject a number of (many) metallic glass spheres from the orifice at one displacement (displacement) and obtain metallic glass spheres with diameter generally equal to the orifice diameter by displacing (vibrating) the cylinder rod 14a toward metallic liquid by the piezoelectric actuator 12. It is needless to say that displacement of the cylinder rod 14a is required to correspond to the total area depending on the diameter of metallic glass sphere ejected and its numbers.
[0182] Further, the frequency of the displacement the piezoelectric actuator 12 is not also limited, can be appropriately selected depending on the type of the target metallic glass sphere (material) and necessary production speed. For the target material described above, for example, nearly 10 Hz to 1 KHz is practical. From the point of mass-productivity of metallic glass sphere, this frequency is possible range, and to be higher is preferable.
[0183] The materials that are possibly produced by the metallic glass sphere production apparatus or metallic glass sphere as production apparatus of monodisperse particle are not particularly limited, and various kinds such as palladium-base, zirconium-base and lanthanum-base are possible to be produced, it is possible to use combining various kinds of materials depending on the application. Accordingly, the temperature of the liquid is not particularly limited provided that it is higher than the melting point of the metals used and in the range in which flowability necessary is obtained.
[0184] Embodiment 4
[0185] The next is to explain the production apparatus of monodisperse particle according to the embodiment of the invention. The embodiment has a same overall arrangement as the other embodiments as described before according to the invention shown in FIG. 7, as shown in FIG. 7, the nozzle part 25 is constituted to be provided with relatively thin supply tube 21c between the cavity 25c and the scrucible 26 as shown in FIG. 12.
[0186] Also in the production apparatus of monodisperse particle according to the embodiment, relation between this orifice diameter &dgr;o and the supply pipe diameter &dgr;f of the supply pipe 21c is set so that the supply pipe diameter &dgr;f is greater than the orifice diameter &dgr;o of the orifice. That is, the orifice diameter is set to be in the range of nearly 30 to 500 &mgr;m, more preferably in the range of nearly 50 to 300 &mgr;m, and further, the supply pipe diameter &dgr;f is set to be in the range of 100 to 900 &mgr;m and greater than the orifice diameter &dgr;o.
EXAMPLE[0187] Examples of the invention are shown below.
Example 1[0188] Thermoelectric semiconductor was produced using the production apparatus of monodisperse particle shown in FIG. 1.
[0189] A. Apparatus Arrangement
[0190] In the production apparatus of monodisperse particle shown in FIG. 1, for piezoelectric actuator 12, laminar type piezoelectric element (NLA-5×5×18 made by Tokin Co.) was used. The capability is that the capacity is 1600 nF(±20%), insulating resistance, 2×108&OHgr; (±50%), maximum displacement, 15.2 &mgr;m/100V(±10%), maximum generating force, 85 kgf/100V. This has slight hysteresis, but generally displace linearly. For diaphram 15, circular plate of stainless with diameter of 3 mm and thickness of 0.2 mm.
[0191] The above maximum displacement (15.2 &mgr;m/100V) is a value when the margin of this piezoelectric actuator is not constrained. However, in here, the piezoelectric actuator is fixed to the actuator press with adhesive, and further this actuator press is fixed to the inside of the holder block 39. Thus, when the piezoelectric actuator is fixed to the apparatus in this way, the relation between applied voltage and displacement is required to be understood. As a result of measurement, in this example, it is found to be expressed as
y=1.134×V (Equation 5)
[0192] where y: displacement (&mgr;m) of diaphram, V: applied voltage (V).
[0193] For the pulse wave generator, personal computer, DA board (MDA-2798BPC made by MicroScience Co.) and low-pass filter were used. And for the power amplifier, fast power amplifier (NF-4025 made by NF KAIRO SEKKEI BLOCK Co.) was used. This amplifier has capability of frequency band DC˜1MH, maximum output voltage, 125V, maximum output current, 11.3Ap-p.
[0194] The orifice was, as shown in FIG. 6, shaped to provided with circular tube on the ejecting part. Further, as shown in FIG. 6, silicon grease was applied on the face on which the material melting liquid contacted.
[0195] In the production apparatus of monodisperse particle 10 of this example, for piezoelectric actuator 12, laminar type piezoelectric element (NLA-5×5×18 made by Tokin Co.), for the pulse wave generator, personal computer and DA board 761AT (made by MicroScience Co.), for the power amplifier, NF-4025 (made by NF KAIRO SEKKEI BLOCK Co.) were used. The above laminar type piezoelectric element used for the piezoelectric actuator 12 had maximum displacement, 14.7 &mgr;m and frequency property, 1.7 MHz.
[0196] In here, by passing cooling water in the water cooling pipe, the piezoelectric element was cooled not raise above 40° C. The members (around actuator, transmission rod 14, nozzle part 25 etc.) that became high temperature were made of ceramics.
[0197] The diameter of the orifice was approximately 200 &mgr;m, while the diameter of the supply pipe 21a was 0.5 mm.
[0198] For raw material of thermoelectric semiconductor, bismuth-base material (Bi-16% Sb) was used in here, heated to 673 K by heater 20 and maintained, and the pressure of the helium gas in the scrucible 26 was 2.94 Kpa. The operating frequency of the piezoelectric 12 was 10 Hz, thermoelectric semiconductor was produced by the operating the apparatus of two minutes.
[0199] For the recovered thermoelectric semiconductor, observation of particle shape by scanning electron microscope (SEM) and observation of particle size (particle diameter) distribution by image analysis apparatus were carried out.
[0200] FIG. 13 shows SEM photograph of thermoelectric semiconductor obtained according to the above example. As shown in FIG. 13, particles close to sphericity were obtained.
[0201] FIG. 14 shows the particle diameter distribution of the obtained particles. The monodisperse particles obtained by the above example are spherical particles of which average particle diameter is 203.1 &mgr;m (standard deviation, 1.63) which is nearly equal to the orifice diameter. For information, according to the results of observation based on the SEM photograph shown in FIG. 13, it was confirmed that sphericity (variation in each diameter of each thermoelectric semiconductor) is within ±2%.
[0202] From these results, the thermoelectric semiconductor obtained by the production apparatus of thermoelectric semiconductor according to the example is the not only to be the so-called monodisperse particle, but also to be excellent in sphericity and to have wide application area.
Example 2[0203] The production process according to the invention was carried out using Pb-63Sn, and the others were same as the example 1. In this case, the liquid level height in the scrucible 26 was 2.5 cm, the liquid back pressure, that is, the difference in pressure between inside and outside of the scrucible 26 was 0.03 kg/cm2, and then the monodisperse particle was produced. As a result, the monodisperse particles which were excellent in sphericity were obtained as the example 1 described above.
Example 3[0204] A. Apparatus Arrangement
[0205] In the production apparatus of monodisperse particle, for piezoelectric actuator 12, laminar type piezoelectric element (NLA-5×5×18 made by Tokin Co.) was used. The capability is that the capacity is 1600 nF(±20%), insulating resistance, 2×108&OHgr; (±50%), maximum displacement, 15.2 &mgr;m/100V(±10%), maximum generating force, 85 kqf/100V. This has slight hysteresis, but generally displaces linearly. For diaphram 15, circular plate of stainless with diameter of 3 mm and thickness of 0.2 mm was used.
[0206] The above maximum displacement (15.2 &mgr;m/100V) is a value when the margin of this piezoelectric actuator is not constrained. However, in here, the piezoelectric actuator is fixed to the actuator press with adhesive, and further this actuator press is fixed to the inside of the holder block 39. Thus, when the piezoelectric actuator is fixed to the apparatus in this way, the relation between applied voltage and displacement is required to be understood. As a result of measurement, in this example, it is found to be expressed as
y=1.134×V (Equation 5)
[0207] where y: displacement (&mgr;m) of diaphram, V: applied voltage (V).
[0208] For the pulse wave generator, personal computer, DA board (MDA-2798BPC made by MicroScience Co.) and low-pass filter were used. And for the power amplifier, fast power amplifier (NF-4025 made by NF KAIRO SEKKEI BLOCK Co.) was used. This amplifier has capability of frequency band DC-1 MHz, maximum output voltage, 125V, maximum output current, 11.3Ap-p.
[0209] The orifice was, as shown in FIG. 5, shaped to be provided with circular tube on the ejecting part. Further, as shown in FIG. 5, silicon grease was applied on the face on which the slurry contacted.
[0210] The drying furnace 42 consists of falling tube 40 made of pilex glass, and heater 41a and 41b installed to cover thereon. The temperature control is carried out by thermocouple inserted between the falling tube 40 and heater 41a, and temperature regulator. Further, to reduce the convection in the drying furnace 42, the recovery box 44 is structured to be sealable.
[0211] B. Preparing Slurry
[0212] Using the production apparatus of ceramics spherical monodisperse particle described above, spherical monodisperse particles composed of &bgr;-tricalcium phosphate (&bgr;-Ca10 (PO4)3, hereinafter, described as &bgr;-TPC) were produced. &bgr;-TPC shattered powder was used as raw powder. Using these, slurry with solid particle concentration of 30% and adding amount of dispersant of 50 mg/ml was prepared.
[0213] C. Filling Slurry
[0214] After preparing slurry, to remove foams in the slurry, vacuum defoaming was carried out for 15 to 30 minutes. The lifter A separated the B1 block to the upper of the apparatus, with this state, the slurry was charged into the slurry retention chamber 21a, and was sufficiently filled up to the slurry retention chamber 21b. After completing filling, the B1 block was put back and then assembled. After that, air around the ceramics spherical monodisperse particle forming part B was discharged by the vacuum suction mechanism part D, and then inert gas was supplied from the inert gas supply source which is not shown. In the example, the barometric pressure at this time was atmospheric pressure.
[0215] D. Adding Pressure Pulse
[0216] Trapezoid pulse waves of 10 Hz shown in FIG. 15 were generated by the pulse generator. For information, voltage of the pulse wave (vertical axis in FIG. 15) is required to be adjusted so that displacement of diaphram 15 is greater than critical displacement of the slurry ejection. That is, using the equation 5, the voltage is derived from the displacement required. For the slurry 1 and 2, the voltage was 6.5 V, and the displacement was 7.37 &mgr;m, for slurry 3, voltage 8 V, displacement 9.07 &mgr;m. The table 1 summaries the ingredients of each slurry, applied voltage and displacement. 1 TABLE 1 Concentration Adding Adding of solid amount of amount of Applied Displace- particle dispersant binder voltage ment (vol. %) (mg/ml) (mg/ml) (V) (&mgr;m) Slurry 1 30 50 0 6.5 7.37 Slurry 2 30 50 15 6.5 7.37 Slurry 3 30 50 30 8 9.07
[0217] E. Drying and Recovery of Slurry Drop
[0218] In order to dry the slurry drop ejected from the orifice, the temperature in the drying furnace 42 was set to 800° C. The dried particles were recovered in the recovery box 44.
[0219] F. Evaluation of Dried Particles
[0220] For the recovered particles, the shape and particle surface were observed with scanning electron microscope. FIG. 16 shows the observed photographs showing the shapes of the obtained dried particles for slurry 1 to 3. Referring to FIG. 16, shape of the obtained dried particles are depressed spheres with recesses, however, it was confirmed that as the adding amount of the binder increases, the shape becomes closer to sphere.
[0221] Further, the images were captured from the optical microscope by CCD camera, and the projected figures were binarised by image software (Mac scope made by Mitani Shoji Co.), thereby, the average particle diameter and particle size distribution were obtained. FIG. 17 shows the results as graph. Referring to FIG. 17, the particle size distribution of the obtained dried particles have the standard deviation of within 10% in any case. In particular, as the adding amount of the binder increases, the standard deviation decreases, for example, for slurry 3 (adding amount of binder 30 mg/ml), it was 4.14%.
[0222] As described above, particularly in the case that the slurry 3 was used, &bgr;-TPC particles with a few recesses, but of which shape is nearly sphere, and of which particle diameter is generally uniform, that is, &bgr;-TPC spherical monodisperse particle was obtained.
Example 4[0223] In the production apparatus of monodisperse particle shown in FIG. 5, the distance from the orifice to liquid level of the liquid nitrogen in the cooling part 45 is 10 cm.
[0224] The slurry 1 to 3 were prepared in the same as that in the example 3, and were ejected from the orifice by the pulse pressure. After recovered in the liquid nitrogen in the cooling part 45, and the cooling part was removed from the apparatus, and then depressurized and sublimed to obtain the dried particles. FIG. 18 shows the observed photograph of each dried powder by scanning electron microscope. Referring to FIG. 18, they have cracks on its surface, however, are in shape of generally spherical particles. However, as the adding amount of binder increases, there appears phenomena that projections occurs on its surface, or multiple spherical particles are connected and large particles are generated. Thus, for dried particles by the slurry 1 in which there is few such phenomena, the average particle diameter and particle size distribution were derived. FIG. 19 shows the results. Referring to FIG. 19, the dried particles by slurry 1, of which particle size distribution has standard deviation of 3.97%, therefore, they are clearly particles with generally uniform particle diameter.
Example 5[0225] In the production apparatus of metallic glass sphere 10 according to the embodiment shown in the above FIG. 7, for piezoelectric actuator 12, laminar type piezoelectric element (AE0505D16 made by Tokin Co.), for the pulse wave generator, personal computer and DA board MDA 761AT (made by NF KAIRO SEKKEI BLOCK Co.), for the power amplifier, NF-4025 (made by NF KAIRO SEKKEI BLOCK Co.) were used. The above laminar type piezoelectric element used for the piezoelectric actuator 12 had maximum displacement, 14.7 &mgr;m and frequency property, 1.7 MHz.
[0226] In here, by passing cooling water in the water cooling pipe, the piezoelectric element was cooled not raise above 40° C. The members (around actuator, transmission rod 14, nozzle part 25 etc.) that became high temperature were made of ceramics. In addition, the orifice plate 23 was also made of ceramics, and sixty orifices were provided in the cross-section (about 40 mm2) of the cylinder rod 14a. The orifice diameter was approximately 400 &mgr;m.
[0227] For raw material of thermoelectric semiconductor, palladium-base material (Pd—Cu—Ni—P: melting temperature approximately 900° C. to 1000° C.) was used in here, heated to 1000° C. by heater 20 and maintained, and the helium gas was introduced into the recovery part C at the pressure of 0.1 atm from the introducing pipe which is not shown. The ejected liquid drop was recovered product recovery box 43 of the recovery part 43 at approximately 50 cm downward from the orifice.
[0228] The operating frequency of the piezoelectric 12 was 100 Hz, and the apparatus was operated for two minutes, then the metallic glass sphere was produced.
[0229] The liquid drop ejected from the orifice was initially set to be received in the sample tray 40, and the forming state was judged by the observation of metal microscope, if it was judged to be correct, the sample tray 40 was removed, and as described before, the liquid drop was recovered in the product recovery box 43 of the recovery part C in the lower part of the orifice.
[0230] For the metallic glass sphere recovered in the product recovery box 43, observation of particle shape by scanning electron microscope (SEM) and measurement of particle size (particle diameter) distribution by image analysis apparatus were carried out. The details are omitted, CCD camera (numerical code 48 in FIG. 1) was installed in the recovery part C, which observes the shape of the metallic glass sphere being produced in real time, and according to this result of the observation the production conditions were regulated.
[0231] FIGS. 20(a), (b) shows the SEM photographs of the metallic glass sphere obtained by the above example. FIG. 20(a) shows the particles obtained when the ejecting temperature was 1000° C., and FIG. 20(b) shows when the ejecting temperature was 900° C. When the ejecting temperature was 1000° C., the particles did not solidify during falling due to the shortage of cooling time and deformed due to the impact of drop, whereas, when the ejecting temperature shown in FIG. 20(b) was 900° C., particles close to sphericity were obtained.
[0232] FIG. 21 shows the particle diameter distribution of the particles obtained when the ejecting temperature was 900° C. shown in FIG. 20(b). The monodisperse particles obtained by the above example were spherical particles of which average particle diameter was 383.9 &mgr;m (standard deviation 4.17) generally equal to the orifice diameter.
[0233] For more information, it was confirmed that sphericity (variation in each diameter for each metallic glass sphere) is within ±2%, according to the result of observation based on the SEM photograph of metallic glass sphere shown in FIG. 20(b).
[0234] Further, by making variation in the size (diameter) among many of individual metallic glass spheres at greatest within 10%, preferably within 5%, more preferably 2%, it is possible to substantially produce monodisperse particles.
[0235] Additionally, the metallic glass spheres produced by this apparatus is characterized to have good surface cleanliness (that is, the thickness of the oxide film layer is very thin).
[0236] From these results, the metallic glass sphere obtained by the production apparatus of metallic glass sphere according to the example is the not only to be the so-called monodisperse particle, but also to be excellent in sphericity and to have wide application area.
[0237] FIG. 22 shows the results of XRD analysis of the particles obtained when the ejecting temperature was 900° C. shown in FIG. 20(b). FIG. 22 shows no remarkable peaks and that the particles becomes amorphous body and vitified.
Example 6[0238] The monodisperse particles according to the invention were produced by the production process according to the invention using tin-based material (Sn-3, 5 wt %Ag) which is lead free solder material, and the others were same as the example 1.
[0239] FIG. 23 shows SEM photograph of the lead free solder spheres recovered in the product recovery box 43. Further, FIG. 24 shows results of measurement of particle size (particle diameter) distribution by image analysis apparatus.
[0240] The monodisperse particles obtained by the above example were spherical particles of which average particle diameter was 187.57 &mgr;m (standard deviation 0.80) generally equal to the orifice diameter.
[0241] For more information, it was confirmed that sphericity (variation in each diameter for each lead free solder sphere) is within ±2%, according to the result of observation based on the SEM photograph of lead free solder sphere shown in FIG. 23.
Example 7[0242] The monodisperse particles according to the invention were produced by the production process according to the invention using lead-based material (Pb-63 wt %Sn), and the others were same as the example 6.
[0243] FIG. 25 shows SEM photograph of the lead tin particles recovered in the product recovery box 43. Further, FIG. 26 shows results of measurement of particle size (particle diameter) distribution by image analysis apparatus.
[0244] The monodisperse particles obtained by the above example were spherical particles of which average particle diameter was 187.57 &mgr;m (standard deviation 0.80) generally equal to the orifice diameter.
[0245] For more information, it was confirmed that sphericity (variation in each diameter for each lead tin particle) is within ±2%, according to the result of observation based on the SEM photograph of lead tin particles shown in FIG. 25.
Example 8[0246] Further, even in the results that metallic glass spheres were produced replacing the raw material, the spherical particles of which average particle diameter is generally equal to the orifice diameter were obtained. The raw materials used in here were zirconium-based Zr—Al—Cu—Ni (melting temperature approximately 950° C. to 1100° C.), lanthanum-based La—Al—Ni—Cu—Co (melting temperature approximately 400° C. to 600° C.).
[0247] The obtained properties such as shapes of particles, particle size (particle diameter) and vitrification ratio were same as those in the previous examples.
[0248] According to each example described above, effects were obtained that it is possible to produce metallic glass sphere with any particle diameter at desired speed from metallic glass liquid with high melting temperature.
[0249] For information, the above examples are just only examples of the invention, an needles to say that this invention is limited to these examples.
[0250] For example, as described before, the diameter of metallic glass sphere desired to be produced can be adjusted by orifice diameter on the orifice plate 23 and the number, diameter of the cylinder rod 14a and the clearance around it, wetability between molten metal and the container, gas pressure of the inert gas in the molten metal container, operating frequency, waveform of the frequency and displacement of the piezoelectric actuator 12, temperature and surface tension of the molten metal. Additionally, the operating frequency of the piezoelectric actuator 12 can be realized to easily reach to approximately 10 Hz to 10 KHz, this allows to control the production speed.
[0251] For information, the above descriptions limited the target that are produced using production apparatus according to the invention to metal glass sphere, however, this production apparatus according to the invention can be suitably used for production of monodisperse particles containing various kinds of alloys with broader range of melting temperature. In this case, as alloy material with high melting point, alloys containing copper, silver and gold can be listed. While, as alloy material with low melting point, alloys containing lead, tin etc. can be listed.
[0252] As described above, the monodisperse particles according to this invention can be obtained by controlling the standard deviation below 5 &mgr;m and the sphericity below 2.5%, therefore this allows the production to be industrially cheap with broad versatility.
[0253] In addition, the monodisperse particles can be obtained by directly recovering as monodisperse particles controlled so that the fundamental conditions are satisfied, therefore, this allows no requirement of classification operation by comb intended especially for enhancing uniformity and efficient production.
[0254] Further, the monodisperse particles according to the invention, which are obtained by ejecting and recovering flowable material per unit, of which standard deviation is below 5 &mgr;m and spherocity is below 2.5%, particle diameter of composing particles is controlled at determined value, therefore, can be produced cheaply and efficiently as monodisperse particles containing particles with diameter corresponding to the application area and adoption area of monodisperse particles.
[0255] Further, the invention allows to realize production process and apparatus in which no classification operation is required, particle size (particle diameter) of individual particles can be more broadly and artificially, and metal glass sphere closer to sphericity, with uniform particle size (particle diameter) can be mass-produced.
[0256] Further, the above production process allows to obtain monodisperse particles with property of high uniformity, particularly, metal glass sphere from raw material of material with high melting point, in particular, metal glass.
Claims
1. A production apparatus of monodisperse particle comprising:
- flowable material retention container for retaining flowable material, supply pipe which is passage to supply flowable material from material container to the flowable material retention container, diaphram closely contacting to the flowable material retention container, orifice provided on the bottom of the flowable material retention container, piezoelectric actuator generating determined pulse pressure, transmission rod transmitting pulse pressure generated by the piezoelectric actuator to the diaphram, and recovery part located downward from the orifice plate and recovering flowable material ejected per unit.
2. A production apparatus of monodisperse particle according to claim 1, wherein supply pipe diameter &dgr;f of the supply pipe and orifice diameter &dgr;o of the orifice satisfy the (Equation 1).
- &dgr;f>&dgr;o (Equation 1)
3. A production apparatus of monodisperse particle according to claim 2, wherein supply pipe diameter is set to be 100 to 900 &mgr;m.
4. A production apparatus of monodisperse particle according to claim 1, wherein supply pipe diameter &dgr;f of the supply pipe and orifice diameter &dgr;o of the orifice satisfy the (Equation 2).
- 0.5<k=(&dgr;f)2/{(&dgr;o)2+(&dgr;f)2}≦0.95 (Equation 2)
5. A production apparatus of monodisperse particle according to claim 1, having measuring device for internal pressure of the material container, measuring device for external pressure of the material container and controller to control internal and external pressure of the material container to determined value.
6. A production apparatus of monodisperse particle according to claim 1, wherein the material container is provided with heater.
7. A production apparatus of monodisperse particle according to claim 1, wherein the recovery part is provided with heater for heating and drying the flowable material.
8. A production apparatus of monodisperse particle according to claim 1, wherein the recovery part is provided with cooler for rapidly cooling and freezing the slurry drop.
9. A production apparatus of monodisperse particle according to claim 1, wherein the orifice is provided on orifice plate having more than one orifice.
10. A production apparatus of monodisperse particle according to claim 9, wherein more than one orifice is removably provided on the orifice plate.
11. A production apparatus of monodisperse particle comprising:
- flowable material retention container for retaining flowable material, supply pipe which is passage to supply flowable material from material container to the flowable material retention container, nozzle part provided on the flowable material retention container, orifice provided on the bottom of the flowable material retention container and for ejecting flowable material in the flowable material retention container, piezoelectric actuator generating determined displacement, transmission rod transmitting displacement generated by the piezoelectric actuator as displacement of cylinder rod inserted into the nozzle part, and recovery part recovering flowable material ejected per unit.
12. A production apparatus of monodisperse particle according to claim 11, wherein supply pipe diameter &dgr;f of the supply pipe and orifice diameter &dgr;o of the orifice satisfy the (Equation 1).
- &dgr;f>&dgr;o (Equation 1)
13. A production apparatus of monodisperse particle according to claim 12, wherein supply pipe diameter is set to be 100 to 900 &mgr;m.
14. A production apparatus of monodisperse particle according to claim 11, wherein supply pipe diameter &dgr;f of the supply pipe and orifice diameter &dgr;o of the orifice satisfy the (Equation 2).
- 0.5<k=(&dgr;f)2/{(&dgr;o)2+(&dgr;f)2}≦0.95 (Equation 2)
15. A production apparatus of monodisperse particle according to claim 11, having measuring device for internal pressure of the material container, measuring device for external pressure of the material container and controller to control internal and external pressure of the material container to determined value.
16. A production apparatus of monodisperse particle according to claim 11, wherein the material container is provided with heater.
17. A production apparatus of monodisperse particle according to claim 11, wherein the recovery part is provided with heater for heating and drying the flowable material.
18. A production apparatus of monodisperse particle according to claim 11, wherein the recovery part is provided with cooler for rapidly cooling and freezing the slurry drop.
19. A production apparatus of monodisperse particle according to claim 11, wherein the orifice is provided on orifice plate having more than one orifice.
20. A production apparatus of monodisperse particle according to claim 19, wherein more than one orifice is removably provided on the orifice plate.
21. A production apparatus of monodisperse particle comprising:
- flowable material retention container for retaining flowable material, supply pipe which is passage to supply flowable material from material container to the flowable material retention container, nozzle part provided on the flowable material retention container, orifice provided on the bottom of the flowable material retention container and for ejecting flowable material in the flowable material retention container, piezoelectric actuator generating determined displacement, transmission rod transmitting displacement generated by the piezoelectric actuator as displacement of cylinder rod inserted into the nozzle part, and recovery part recovering flowable material ejected per unit, wherein space area Af between inside of the nozzle part and the cylinder rod, and cross-sectional area Ao satisfy the (Equation 3).
- Af>Ao (Equation 3)
22. A production apparatus of monodisperse particle according to claim 21, wherein the recovery part is provided with heater for heating and drying the flowable material.
23. A production apparatus of monodisperse particle according to claim 21, wherein the recovery part is provided with cooler for rapidly cooling and freezing the slurry drop.
24. A production process of monodisperse particle in which flowable material is supplied from material container to flowable material retention container through supply pipe, and flowable material retained in the flowable material retention container is ejected to recovery part by displacement transmission means connected to piezoelectric actuator generating determined displacement through orifice and recovered, wherein supply pipe diameter &dgr;f of the supply pipe is set to be greater than orifice diameter &dgr;o of the orifice.
25. A production process monodisperse particle according to claim 24, wherein ejected material is dried and recovered by heating.
26. A production process monodisperse particle according to claim 24, wherein difference in pressure between internal and external pressure of the material container is measured, and the internal and external pressure of the material container is controlled at determined value based on the measurement.
27. A production process monodisperse particle according to claim 24, wherein the control of difference in pressure between internal and external pressure of the material container is carried out based on the (Equation 4).
- 0≦P<Pc (Equation 4)
- P: Difference in pressure=Internal pressure (Pi) of the material container−External pressure (Po) of the material container
- Pc: Limit difference in pressure=Difference in pressure between limit internal pressure (Pi) of the material container and limit external pressure (Po) of the material container when the slurry flows down from the orifice by its own weight.
28. A production process monodisperse particle according to claim 24, wherein particle diameter of recovered monodisperse particle is controlled by orifice diameter of the orifice.
29. A production process monodisperse particle according to claim 28, wherein particle diameter of monodisperse particle is controlled to 0.9 to 1.1 times of orifice diameter.
30. A production process monodisperse particle according to claim 24, wherein the flowable material is molten metal which is melted in material container provided with heater.
31. A production process monodisperse particle according to claim 24, wherein the flowable material is ejected to the recovery part as liquid drop from more than one orifice.
32. A production process monodisperse particle according to claim 24, wherein particles contained in the monodisperse particle are metallic glass spheres.
33. A monodisperse particle produced by the production process described in claim 24, wherein standard deviation is below 2 &mgr;m.
34. A monodisperse particle produced by the production process described in claim 24, wherein monodisperse particle is obtained by controlling individual particle diameter of particles contained in monodisperse particle to 0.9 to 1.1 times of the orifice diameter.
35. A monodisperse particle produced by the production process described in claim 24, wherein variation in diameter of individual particles contained in monodisperse particle is within ±10%.
36. A monodisperse particle according to claim 35, wherein variation in diameter of individual particles contained in monodisperse particle is within ±2%.
37. A production process of monodisperse particle in which flowable material is supplied from material container to flowable material retention container through supply pipe, and flowable material retained in the flowable material retention container is ejected to recovery part by displacement transmission means connected to piezoelectric actuator generating determined displacement through orifice and recovered, wherein flow rate per unit of flowable material in the supply pipe is greater than that in the orifice.
38. A production process monodisperse particle according to claim 37, wherein ejected material is dried and recovered by heating.
39. A production process monodisperse particle according to claim 37, wherein difference in pressure between internal and external pressure of the material container is measured, and the internal and external pressure of the material container is controlled at determined value based on the measurement.
40. A production process monodisperse particle according to claim 37, wherein the control of difference in pressure between internal and external pressure of the material container is carried out based on the (Equation 4).
- 0≦P<Pc (Equation 4)
- P: Difference in pressure=Internal pressure (Pi) of the material container−External pressure (Po) of the material container
- Pc: Limit difference in pressure=Difference in pressure between limit internal pressure (Pi) of the material container and limit external pressure (Po) of the material container when the slurry flows down from the orifice by its own weight.
41. A production process monodisperse particle according to claim 37, wherein particle diameter of recovered monodisperse particle is controlled by orifice diameter of the orifice.
42. A production process monodisperse particle according to claim 41, wherein particle diameter of monodisperse particle is controlled to 0.9 to 1.1 times of orifice diameter.
43. A production process monodisperse particle according to claim 37, wherein the flowable material is molten metal which is melted in material container provided with heater.
44. A production process monodisperse particle according to claim 37, wherein the flowable material is ejected to the recovery part as liquid drop from more than one orifice.
45. A production process monodisperse particle according to claim 37, wherein particles contained in the monodisperse particle are metallic glass spheres.
46. A monodisperse particle produced by the production process described in claim 37, wherein standard deviation is below 2 &mgr;m.
47. A monodisperse particle produced by the production process described in claim 37, wherein monodisperse particle is obtained by controlling individual particle diameter of particles contained in monodisperse particle to 0.9 to 1.1 times of the orifice diameter.
48. A monodisperse particle produced by the production process described in claim 37, wherein variation in diameter of individual particles contained in monodisperse particle is within ±10%.
49. A monodisperse particle according to claim 48, wherein variation in diameter of individual particles contained in monodisperse particle is within ±2%.
50. A production process in which ejected flowable material is rapidly cooled and frozen, and depressurized while keeping the frozen particles so that liquid phase does not appear, and solid phase is sublimed by slowly heating, then recovered as frozen dried particles.
Type: Application
Filed: Jun 12, 2002
Publication Date: Dec 5, 2002
Inventor: Akira Kawasaki (Sendai-shi)
Application Number: 10170126
