Abstract: In a heat history initializing step, a heat treatment in performed in an atmosphere including at least one of hydrogen, helium, and argon while the temperature is increased in a range of 700.degree. C. to 1,000.degree. C. at a rate of 15.degree.-1,000.degree. C./min. In a controlled nuclei growing step, a heat treatment is performed in the above atmosphere while the temperature is kept constant in a range of 850.degree. C. to 980.degree. C. for 0.5-60 minutes.

Abstract: A ceramic porous body is constituted of ceramic particles which have a substantially continuous, monotonic size distribution in the thickness direction of the porous body.

Abstract: A silicon wafer is mirror-polished until obtaining surface roughness Ra of 0.70-1.00 nm, Rq of 0.80-1.10 nm, or Rt of 4.50-7.00 nm. The resulting wafer is heat-treated at a temperature not lower than 1,200.degree. C. for 30 minutes to 4 hours in a hydrogen gas atmosphere. According to another aspect, a silicon wafer is mirror-polished until obtaining surface roughness values Ra' of 0.08-0.70 nm, rms of 0.10-0.90 nm, and P-V of 0.80-5.80 nm in a square area of 90 .mu.m by 90 .mu.m, and surface roughness values Ra' of 0.13-0.40 nm, rms of 0.18-0.50 nm, and P-V of 1.30-2.50 nm in a square area of 500 nm by 500 nm. The resulting wafer is heat-treated at 1,100.degree.-1,300.degree. C. for 30 minutes to 4 hours in a hydrogen gas atmosphere.

Abstract: The present invention provides a recycle slide gate plate, said slide gate plate being connected to a lower portion of a molten metal container and used for sliding a plate to control a flow of molten metal drained from the molten metal container, comprising an upper plate and/or a lower plate obtained by polishing a sliding surface of a slide gate plate used at least one time, at a predetermined smoothness tolerance, a tubular ring fixed to a through hole obtained by cutting out a molten metal outlet portion of the upper plate and/or the lower plate having a projecting portion on a side opposite to a sliding surface of the upper plate and/or the lower plate, said projecting portion having a total height of a sum of a height dimension substantially equal to a height of a projecting portion of a new plate before use and a thickness dimension to be reduced by polishing out the sliding surface, the projecting portion being provided with a molten metal outlet hole formed inside the projecting portion, and a cushi

Abstract: When a Si single crystal 8 is pulled up from a melt 6 received in a crucible 2, the state of eddy flows generated in the melt 6 is judged from the temperature distribution of the melt at the surface. According to the result of judgement, the gas, i.e. N.sub.2, Xe or Kr, which causes extraoridnary deviation in the density of a melt 6 is added to an atmospheric gas, so as to keep the eddy flows under unstabilized condition. The effect of said gas is typical in the case of crystal growth from the melt to which a dopant such as Ca, Sb, Al, As or In having the effect to suppress the extraordinary deviation in the density is added. Since the single crystal is pulled up from the melt held in the temperature-controlled condition at the surface, impurity distribution and oxygen distribution are made uniform along the direction of crystal growth. A single crystal obtained in this way has highly-stabilized quality.

Abstract: When a B or P-doped Si single crystal is pulled up from a B or P-doped melt by the Czochralski method, an element such as Ga, Sb or In having the effect to reduce the heat expansion coefficient of said melt at a temperature near the melting point is added to said melt. The additive element stabilizes the temperature condition of crystal growth so as to control the generation of eddy flows just below the interface of crystal growth.When a Ga or Sb-doped Si single crystal is pulled up from a Ga or Sb-doped melt, an element such as B or P having the effect to increase the heat expansion coefficient of said melt at a temperature near the melting point is added. The agitation of the melt just below the interface of crystal growth is accelerated by the addition of B or P, so as to assure the growth of a Si single crystal from the melt having impurity distribution made uniform along the radial direction.

Abstract: When a single crystal is pulled up from a melt, the difference .DELTA.T between temperatures at the bottom of a crucible and at the interface of crystal growth is controlled so as to hold the Rayleigh constant defined by the formula of:R a=g.multidot..beta..multidot..DELTA.T.multidot.L/.kappa..multidot..nu.within the range of 5.times.10.sup.5 -4.times.10.sup.7, wherein g represents the acceleration of gravity, .beta. the volumetric expansion coefficient of the melt, L the depth of the melt, .kappa. thermal diffusivity and .nu. the kinematic viscocity. Since the convection mode of the melt at the interface of crystal growth is constantly held in the region of soft turbulence, a single crystal is grown under the stabilized temperature condition without the transfer of the impurity distribution in the melt into the growing single crystal.

Abstract: Provided is a refractory for casting which contains clinker having a mineral crystal phase consisting essentially of mullite and baddeleyite. The refractory for casting has excellent in a thermal-shock resistance, corrosion resistance and strength. The refractory for casting is manufactured from a raw material containing a refractory composition and an organic binder, wherein the refractory composition comprises(a) 3 to 60 wt % of clinker having a mineral crystal phase consisting essentially of mullite and baddeleyite, and containing 5 to 22 wt % of alumina (Al.sub.2 O.sub.3), 38 to 68 wt % of zirconia (ZrO.sub.2) and 27 to 40 wt % of silica;(b) 5 to 40 wt % of at least one carbon-based material selected from the group consisting of graphite and carbon; and(c) at least one refractory element as a balance, selected from the group consisting of alumina, fused silica, zirconia, silicon carbide, mullite and a metal silicon.

Abstract: A slide gate plate serving as a molten metal flow-rate control member for use in a molten metal discharging device, comprising an assembly of at least one stationary plate having a nozzle hole therein and a slide plate having a nozzle hole therein, the plates being designed so that one of the plates is thicker than the other plate by 1.5 mm or more. With this construction, the slide gate plate is reusable by polishing the sliding face off a worn plate for reuse.

Abstract: Quartz material is subjected to a heat contact treatment with ammonia gas at 1200.degree. C. less under the presence of a carbon generating source to form a silicon oxynitride layer on the surface of the quartz material easily and rapidly. The obtained surface-treated quartz material has excellent heat resistance, and no exfoliation of the silicon oxynitride layer from the quartz material occurs even when it is subjected to a repetitive heat cycle. Further, if a second surface treatment step of coating a silicon nitride film on the silicon oxynitride layer using a CVD method or the like is performed after the surface treatment step of forming the silicon oxynitride layer on the surface of the quartz material, the heat resistance is more improved.

Abstract: According to the present invention, there is provided a sliding gate plate connected to a molten metal container, used as a part of a nozzle, for controlling a flow amount of molten metal in the molten metal container, comprising a main body of the sliding gate plate, having a through-hole at a section corresponding to a molten metal discharge control, and a cylinder having a ring-like fringe portion, and fit into the through-hole of the main body of the plate.

Abstract: A vertical boat for holding a plurality of semiconductor wafers comprising two end members (5) positioned at the top and the bottom of the vertical boat, and a plurality of support members (3,4) vertically mounted on the end members (5), the support members (3,4) including two front support members (3) located on the wafer inserting side and at least one rear support members (4) located on the rear side of the boat, each support member (3,4) having a series of slits (3a,4a) formed thereon at a predetermined interval and a series of support portions defined by the slits (3a,4a) for supporting semiconductor wafers (1), wherein the front support member (3) is generally formed by a circular arc plate, and wherein each angle (A,B) formed between the wafer inserting direction (X) and a line linking the front end (3b) of the support portion of the front support member (3) to the center (1a) of the wafer (1) is 100 degrees or more.

Abstract: End members are located at the top and the bottom of a vertical heat treatment device. A plurality of support members are vertically mounted on the end members. A plurality of wafer hold members are fixed on the support members in a parallel manner, each of which is formed in an approximately circular arc shape. The wafer hold member is made of SiC by a CVD method or Si3N4 by a CVD method. The wafer hold member has a plate portion on which a wafer is to be placed and a reinforce portion connected to the plate portion. The plate portion is 100-1000 microns in thickness.

Abstract: A vertical boat for holding a plurality of semiconductor wafers comprising two end members (2) positioned at the top and the bottom of the vertical boat, and a plurality of support members (3,4,5,6,104) vertically mounted on the end members (2) for supporting the wafers, wherein each support member (3,4,5,6,104) is formed by a plate-like member having a series of slits (9,10,7,8,108) formed thereon in such a manner that a plurality of support arms are defined by the slits (9,10,7,8,108) at a predetermined interval, each support arm having a support projection (11,12,13,14,112) formed at the end thereof, and wherein the inner portions (P) of the wafer (1) is to be supported by the support projections (11,12,13,14,112) whereas the periphery of the wafer (1) does not contact the arms of the support members (3,4,5,6,104).

Abstract: Aluminium borate whiskers by which a composite material having a higher strength than ever is available by definitely suppressing a generation of spinel along the surface of the whiskers are prepared by heating aluminium borate whiskers bearing a r-alumina surface layer in an atmosphere of ammonia gas or ammonia gas and a hydrocarbon gas such that a layer of a nitro-oxide and oxide of aluminium is generated along the surface of the whiskers.

Abstract: In a slide gate plate apparatus for casting to be installed at an outlet of a molten metal vessel, one or two fixed plates and one slide plate are retained integrally by retaining means through a shell wound round the side face of the fixed plate(s) and a shell wound round the side face of the slide plate. In this retained state, the fixed plate(s) and the slide plate are mounted together to a predetermined position of the molten metal vessel.

Abstract: A ceramic device is disclosed that has a silicon base plate, a first ceramic film formed on a first surface of the silicon base plate, a second ceramic film formed on a second surface of the silicon base plate opposite to the first surface, and an operation opening formed in the silicon base plate between the first and second surfaces. A surface portion of the first ceramic film exposed to the operation opening Is a mirror surface having 0.05 micrometers or less of center line average height Ra. A mirror surface keeping film can be formed between the first surface of the silicon base plate and the first ceramic film for keeping a mirror surface in an etching step to etch the silicon base plate, and the silicon base plate can be reduced partially in the etching step for forming an operation opening thereby exposing a corresponding portion of the mirror surface keeping film to the operation opening.

Abstract: Piezoelectric elements are attached to both sides of a flexible metal thin plate, thus forming a bimorph-type piezoelectric vibrator. A portion of the metal thin plate is extended to form a stirring blade. A suitable weight is attached to a part of the metal plate such that the amplitude of the blade is made greater than the amplitude of the vibrator itself. The voltage to be applied to the vibrator and the frequency are adjusted, and the vibrator is vibrated in a second-order mode. Thereby, the entire solution is moved simultaneously, vertical motion is caused, and the stirring efficiency is enhanced.

Abstract: A mirror for SOR includes a base (1) made of a heat resistant ceramic material having a surface, a first SiC coating (2, 3) formed on the surface of the base (1), which has a first smoothed surface, and a second SiC coating (4, 5) formed on the first smoothed surface of the first SiC coating (2, 3), which has a second smoothed surface. A third SiC coating can be formed on the smoothed surface of the second SiC coating (4).

Abstract: A method for forming a nozzle employed in continuous casting is provided in which powder refractory materials are pressed with low hydrostatic pressure to produce preforms for an edge portion, an inner hole portion, and a powder line portion, these preforms are combined one after another in a rubber mold employing a mandrel while filling the rubber mold with a powdered refractory material for a body portion of the nozzle, and then a nozzle configuration is formed by pressing the rubber mold with a higher hydrostatic pressure than that used to produce the preforms.