Abstract: A process of producing a maraging steel includes melting a steel of a defined composition, casting the molten steel to obtain a steel ingot, hot forging the steel ingot at a forging ratio of at least 4, then soaking the forged piece one or more times to keep the forged piece in a temperature range of 1100-1280° C. for 10-100 hours, and then plastic working the forged piece. A process of producing a maraging steel of another defined composition includes casting the molten steel to obtain a steel ingot with a defined taper, a defined height to diameter ratio and a defined flatness ratio and plastic working the steel ingot so that the size of a nonmetallic inclusion is 30 ?m or less expressed as the diameter of a circle of circumference equal to the perimeter (“circumference”) of the inclusion.

Abstract: A surface treating process according to the present invention, a vapor deposited film is formed from an easily oxidizable vapor-depositing material on the surface of a work by evaporating the vapor-depositing material in a state in which the vapor deposition controlling gas has been supplied to at least zones near a melting/evaporating source and the work within a treating chamber. Thus, the vapor deposited film can be formed stably on the surface of a desired work without requirement of a long time for providing a high degree of vacuum and without use of a special apparatus. In addition, the use of the surface treating process ensures that a corrosion resistance can be provided to a rare earth metal-based permanent magnet extremely liable to be oxidized, without degradation of a high magnetic characteristic of the magnet.

Abstract: Permanent magnets in which the ferromagnetic phase is matched with the grain boundary phase, and permanent magnets in which magnetocrystalline anisotropy in the vicinity of the outermost shell of the major phase is equivalent in intensity to that in the inside to suppress nucleation of the reverse magnetic domain, more specifically having a magnetocrystalline anisotropy not less than one-half the magnetocrystalline anisotropy of the interiors of the ferromagnetic grains, are disclosed.

Abstract: A thermoelectric conversion material is formed of a polycrystal structure of crystal grains composed of a silicon-rich phase, and an added element-rich phase in which at least one type of added element is deposited at the grain boundary thereof, the result of which is an extremely large Seebeck coefficient and low thermal conductivity, allowing the thermoelectric conversion rate to be raised dramatically, and affording a silicon-based thermoelectric conversion material composed chiefly of silicon, which is an abundant resource, and which causes extremely low environmental pollution.

Abstract: A surface treating holder includes a wire which is coiled at distances in such a manner that it is formed as a spring-like tubular structure having spiral-line faces at opposite ends thereof, so that works are accommodated in the tubular structure. A process for surface-treating a pluarlity of works accommodates the works in the holder, and surface treating the works in the holder while being rotated about an axis of the works.

Abstract: A process for treating surfaces of rare earth metal-based permanent magnets, comprising removing an oxide layer formed on a surface of each of the permanent magnets using a blasting apparatus. The apparatus comprises a tubular barrel formed of a mesh net for accommodation of work pieces and supported circumferentially outside a center axis of a support member rotatable about the center axis, and an injection nozzle disposed to inject a blast material against the work pieces from the outside of the tubular barrel, wherein at least one of the tubular barrel and the support member is detachably mounted. The process further comprises removing the tubular barrel or the support member from the blasting apparatus and attaching the tubular barrel or the support member to a vapor deposited film forming apparatus, where a metal film is formed on the surface of each of the permanent magnets by a vapor deposition process.

Abstract: A method for cutting a rare earth alloy using a wire with abrasive grains fixed to a core wire, including the step of cutting the rare earth alloy with the wire traveling in a state that a portion of the rare earth alloy to be cut with the wire is immersed in a coolant containing water as the main component, the coolant having a surface tension at 25° C. in a range of 25 mN/m to 60 mN/m.

Abstract: Rare earth alloy powder having an oxygen content of 50 to 4000 wt. ppm and a nitrogen content of 150 to 1500 wt. ppm is compacted by dry pressing to produce a compact. The compact is impregnated with an oil agent and then sintered. The sintering process includes a first step of retaining the compact at a temperature of 700° C. to less than 1000° C. for a period of time of 10 to 420 minutes and a second step of permitting proceeding of sintering at a temperature of 1000° C. to 1200° C. The average crystal grain size of the rare earth magnet after the sintering is controlled to be 3 &mgr;m to 9 &mgr;m.

Abstract: Permanent magnets in which the ferromagnetic phase is matched with the grain boundary phase, and permanent magnets in which magnetocrystalline anisotropy in the vicinity of the outermost shell of the major phase is equivalent in intensity to that in the inside to suppress nucleation of the reverse magnetic domain, more specifically having a magnetocrystalline anisotropy not less than one-half the magnetocrystalline anisotropy of the interiors of the ferromagnetic grains, are disclosed.

Abstract: A method for producing a compact of rare earth alloy powder of the present invention includes: a powder-filling step of filling rare earth allow powder in a cavity formed by inserting a lower punch into a through hall of a die of a powder compacting machine; and a compression step of pressing the rare earth alloy powder while applying a magnetic field, the steps being repeated a plurality of times. When the (n+1)th (n is an integer equal to or more than 1) stage compression step is to be carried out, the top surface of a compact produced in the n-th stage compression step is placed at a position above the bottom surface of a magnetic portion of a die.

Abstract: It is an object of the present invention to provide a magnetic field generator for MRI with which it is possible to lower the residual magnetism and eddy current within pole pieces generated by the effect of the pulse current flowing through Gradient magnetic field coils, without decreasing the field uniformity within the air gap. Pole pieces 40 in which a main component 41 consisting of laminated silicon steel sheets is effectively combined with a magnetic annular protrusion 42 disposed on the side on the main component 41 facing the air gap, the result of which is the formation of a static magnetic field having the desired uniformity within the air gap without leading to a state of magnetic saturation in the vicinity of the magnetic annular protrusion 42. This also makes possible a reduction in the residual magnetism and eddy current within the pole pieces 40 generated by the effect of the pulse current flowing through Gradient magnetic field coils.

Abstract: The present invention provides a maraging steel excellent in fatigue characteristics and a process for the production thereof. A maraging steel of the first embodiment of the present invention has a chemical composition consisting essentially of, in % by weight: C: 0.01% or less, Ni: 8-19%, Co: 8-20%, Mo: 2-9%, Ti: 0.1-2%, Al: 0.15% or less, N: 0.003% or less, O: 0.0015% or less, and the balance Fe and the Ti component segregation ratio and the Mo component segregation ratio in its structure of 1.3 or less each. A maraging steel of the second embodiment of the present invention has the above composition and contains a nonmetallic inclusion in its structure having a size of 30 &mgr;m or less. The maraging steel of the second embodiment can be obtained easily by appropriate plastic working of a steel ingot with a taper Tp=(D1−D2)×100/H of 5.0-25.0%, a height-diameter ratio Rh=H/D of 1.0-3.0, and a flatness ratio B=W1/W2 of 1.5 or less.

Abstract: A dielectric ceramic composition wherein the dielectric constant ∈ is large, the temperature coefficient &tgr;f of the resonance frequency is close to 0, and which as a large Q value, is obtained by adding to and blending with a ceramic composition whose &tgr;f of the resonance frequency is large on the plus side a ceramic composition whose temperature coefficient &tgr;f is large on the minus side. In an Li2O—R2O3—TiO2-based composition, an improved dielectric constant ∈ can be achieved by introducing a specific quantity of Bi2O3, and &tgr;f can be shifted to the plus side and in addition a considerable improvement in Qf achieved by introducing a specific quantity of MO, where M is one or two of Ca and Sr. Furthermore, by introducing a specific quantity of Na2O together with the MO (where M is one or two of CA and Sr), in particular in the case of material of ∈r>150, it is possible to control &tgr;f to the vicinity of 0 while maintaining Qf at an high value.

Abstract: The method for producing a solder bump transfer sheet of the invention includes the steps of: providing a sheet having a chromium oxide layer containing substantially no iron oxide as the outermost surface; and forming a plurality of solder bumps placed in a predetermined pattern on the chromium oxide layer.

Abstract: A permanent-magnet-type magnetic field generator (10) capable of generating a strong magnetic field not weaker than 3 T in a magnetic field generation space (12) is provided. The magnetic field generator (10) has an axially central portion serving as the magnetic field generation space (12), and includes a first magnetic circuit (14) provided by a Halbach array at an outer central portion, and a second magnetic circuit (16) formed inside the first magnetic circuit (14) to surround the magnetic field generation space (12). The first magnetic circuit (14) is provided by permanent magnets (20a)-(20f) and central portions (A) of permanent magnets (22a)-(22f). The second magnetic circuit (16) is provided by a pair of pole pieces (24a) and (24b) each having a saturation magnetism not smaller than 1.6 T, and central portions (B) of permanent magnets (26a)-(26d) which provides magnetic interconnection between the pole pieces (24a) and (24b).

Abstract: A powder for forming a R—Fe—B bonded magnet, wherein an R compound, such as an R oxide, an R carbide, an R nitride or an R hydride, which is contained in a raw material powder such as a super rapidly cooled powder or a hydrogen treated powder (HDDR powder) and reacts with water vapor to change into R(OH)3, has been converted to a R hydroxide R(OH)3 being stable in the air by subjecting the raw material powder to a heat treatment in an atmosphere of a pressured water vapor. The powder for forming an R—Fe—B bonded magnet is free from the generation of a white powder in the surface of or inside a bonded magnet formed from the powder and accordingly, is free from the occurrence or cracking, chipping, swelling or the like in the bonded magnet caused by volume expansion of a white powder.

Abstract: An iron-based rare earth alloy magnet has a composition represented by the general formula: (Fe1-mTm)100-x-y-zQxRyMz, where T is at least one element selected from the group consisting of Co and Ni; Q is at least one element selected from the group consisting of B and C; R is at least one rare earth element substantially excluding La and Ce; and M is at least one metal element selected from the group consisting of Ti, Zr and Hf and always includes Ti. In this formula, the mole fractions x, y, z and m meet the inequalities of: 10 at %<x≦20 at %; 6 at %≦y<10 at %; 0.1 at %≦z≦12 at %; and 0≦m≦0.5, respectively.

Abstract: A phosphorus-copper brazing material formed of a phosphorus-copper brazing alloy which can easily be cold-worked into a thin sheet, a brazing sheet having a brazing layer of the phosphorus-copper brazing alloy, and a flow path structure for heat exchangers constructed by brazing with the alloy, are such that the phosphorus-copper brazing material includes a phosphorus-copper brazing alloy containing Cu as a major component and phosphorus of not less than about 2.0 mass % to not more than about 3.2 mass %. The brazing sheet includes a metal sheet, and a brazing material layer that is integral with the metal sheet on at least one side of the metal sheet, the brazing material layer being formed of the phosphorus-copper brazing alloy. The metal sheet may be formed of copper or a copper alloy containing Cu as a major component.

Abstract: The production is performed by calcining ferrite magnetic powder in which La is substituted for part of Sr and Ti, Zn, and Co are substituted for part of Fe at temperatures of 1100° C. to 1450° C. The magnetization is improved by substituting Zn for part of Fe, and by substituting Ti for part of Fe for the purpose of charge compensation. In addition, the coercive force is improved by substituting Co for part of Fe, and by substituting La for part of Sr for the purpose of charge compensation. Ti is used for the charge compensation, so that it is possible to reduce the cost.

Abstract: A powder pressing apparatus comprises a die having a through hole, an upper punch and a lower punch. At least one of the upper and lower punches has a punching surface having an edge portion provided with a projection. The projection has a tip chamfered by a width not greater than 0.5 mm. The punching surface has a slope having a surface roughness Ra not greater than 1.0 &mgr;m. A rare-earth alloy powder is fed into a cavity formed in the through hole of the die. The rare-earth alloy powder in the cavity is oriented by magnetic field, and pressed by using the upper and lower punches. The upper punch and the lower punch are brought closest to each other at a minimum distance not smaller than 1.7 mm during the pressing. An obtained compact is used for manufacture of a sintered body and a voice coil motor.