Abstract: Provided is an aluminum nitride sintered body excellent in thermal shock resistance and strength and applicable to a radiating substrate for a power module or a jig for semiconductor equipment employed under a strict heat cycle. An aluminum nitride sintered body obtained with a sintering aid of a rare earth element and an alkaline earth metal element contains 0.01 to 5 percent by weight of an alkaline earth metal element compound in terms of an oxide and 0.01 to 10 percent by weight of a rare earth element compound in terms of an oxide, and the amount of carbon remaining in the sintered body is controlled to 0.005 to 0.1 percent by weight, thereby suppressing grain growth and improving thermal shock resistance and strength of the sintered body.

Abstract: A method for producing a sintered silicon carbide body which has excellent strength and the like and in which cracking and breaking are prevented is provided. In the method for producing a sintered silicon carbide body, metallic silicon is, in a vacuum atmosphere or in a non-oxidizing atmosphere, impregnated into a molded body containing silicon carbide and carbon so as to form an impregnated body, and the impregnated body is cooled in a state of being provided with a temperature distribution of 0.1-1.5° C./cm.

Abstract: A silicon nitride sintered product comprising silicon nitride grains and a grain boundary phase, wherein the grain boundary phase consists essentially of a single phase of a LU4Si2O7N2 crystal phase, and the composition of the silicon nitride sintered product is a composition in or around a triangle ABC having point A: Si3N4, point B: 28 mol % SiO2-72 mol % LU2O3 and point C: 16 mol % SiO2-84 mol % LU2O3, as three apexes, in a ternary system phase diagram of a Si3N4—SiO2—LU2O3 system. Also disclosed is a silicon nitride sintered product comprising silicon nitride grains and a grain boundary phase of an oxynitride, wherein the composition of the sintered product is a composition in a triangle having point A: Si3N4, point B: 40 mol % SiO2-60 mol % LU2O3 and point C: 60 mol % SiO2-40 mol % LU2O3, as three apexes, in a ternary system phase diagram of a Si3N4-SiO2-LU2O3 system.

Abstract: A zirconia based article having a core of ZrO2 and/or partially reduced ZrO2, is characterized in that it includes, over at least part of its surface, a superficial layer integral with the article, the thickness of the superficial layer including a plurality of regions of which one external region is formed of zirconium nitride having a gold metallic appearance.

Abstract: A transparent scintillator material for rapid conversion of exciting radiation, such as x-rays, to scintillating radiation. The scintillator material has a cubic garnet host, and has praseodymium as an activator. The scintillator material may be a polycrystalline ceramic material. The polycrystalline ceramic is formed by sintering a powder formed by precipitation. The scintillator material may be integrated into computed tomography (CT) equipment or other x-ray imaging equipment. The scintillator material may also be integrated into a fast response x-ray detector system.

Abstract: A method of firing a green cordierite-ceramic honeycomb structural body containing a carbonaceous material, for example, an organic binder, comprising a two phase process. The first phase comprises firing the green honeycomb structural body in a firing atmosphere to a temperature and for a time sufficient to initiate and sufficiently achieve release of the carbonaceous material while introducing into the firing atmosphere a fluorine-free low-oxygen gas comprising less than about 20% O2, by volume. Once the carbonaceous material is sufficiently released, the second phase involves conventionally firing the green body for a time and a temperature sufficient to initiate and sufficiently achieve the conversion of the green ceramic honeycomb structural body into a fired honeycomb body.

Abstract: A non-reducing dielectric ceramic contains Ca, Zr and Ti as metallic elements and does not contain Pb. In a CuK&agr; X-ray diffraction pattern, the ratio of the maximum peak intensity of secondary crystal phases to the maximum peak intensity at 2&thgr;=25° to 35° of a perovskite primary crystal phase is about 12% or less, the secondary crystal phases including all the crystal phases other than the perovskite primary crystal phase. The non-reducing dielectric ceramic exhibits superior insulating resistance and dielectric loss after firing in a neutral or reducing atmosphere and high reliability in a high-temperature loading lifetime test and is useful for producing compact high-capacitance monolithic ceramic capacitors.

Abstract: An alumina-based composite sintered material comprising alumina as a main ingredient and containing one or more carbonitridation products of groups IVa, Va and VIa of the periodic table and/or two or more carbonitridation products of solid solutions of groups IVa, Va and VIa of the periodic table. The content of nitrogen solid solute in the carbonitridation product increases from the interior to the surface of the sintered material, and the Vickers hardness at the surface of the sintered material is 19.5 GPa or more.

Abstract: A composition and method of fabricating pressureless sintered 70 volume % silicon nitride—30 volume % barium aluminum silicate ceramic composites. The composites are made from 70 volume % silicon nitride, containing varying amounts and size distributions of initial &bgr;-silicon nitride, and 30 volume % barium aluminum silicate. The resulting ceramic composites contain microstructures with coarse &bgr;-silicon nitride whiskers, as well as narrow distributions of short &bgr;-silicon nitride whiskers, surrounded by fine barium aluminum silicate grains. The resulting composites exhibit improved fracture toughness and flexural strength.

Abstract: Molybdenum disilicide/&bgr;′-Si6-zAlzOzN8-z, wherein z=a number from greater than 0 to about 5, composites are made by use of in situ reactions among &agr;-silicon nitride, molybdenum disilicide, and aluminum. Molybdenum disilicide within a molybdenum disilicide/&bgr;′-Si6-zAlzOzN8-z eutectoid matrix is the resulting microstructure when the invention method is employed.

Abstract: A process is described for producing a conductive sintered body based on silicon carbide, in which a) silicon carbide particles, optionally pretreated with a surface modifier, are dispersed in an aqueous and/or organic medium and positive or negative surface charges are generated on the silicon carbide particles by adjustment of the pH of the dispersion obtained; b) carbon black and boron carbide are mixed in as sintering aids, where at least the carbon black particles have a surface charge opposite to the surface charge of the silicon carbide particles and the boron carbide can also be added, completely or in part, at a later point in time (stage c′)); c) the slip thus obtained is shaped directly to form a green body or c′) a sinterable powder is isolated from the slip obtained and is shaped to form a green body, where the above boron carbide can also be added to this sinterable powder; and d) the green body obtained is subjected to pressureless sintering to form a sintered body in essential

Abstract: A method for producing a NOx sensor comprises the steps of forming electrodes on ceramic green sheets, and stacking and integrating the ceramic green sheets into one unit followed by sintering to prepare a substrate, wherein an oxygen concentration is controlled to be not more than 0.5% in a sintering atmosphere after removal of a binder in the step of sintering the substrate. Specifically, the sintering is performed in an atmospheric atmosphere in Interval 1 in which the temperature in a furnace is changed from room temperature to about 1000.degree. C., and the sintering is performed in a nitrogen atmosphere (oxygen concentration in the atmosphere in the furnace is controlled to be about 400 ppm) in Interval 2 in which the temperature is changed from 1000.degree. C. to a maximum temperature followed by spontaneous radiational cooling.

Abstract: A method of firing a green cordierite-ceramic honeycomb structural body containing a carbonaceous material, for example, an organic binder, comprising a two phase process. The first phase comprises firing the green honeycomb structural body in a firing atmosphere to a temperature and for a time sufficient to initiate and sufficiently achieve release of the carbonaceous material while introducing into the firing atmosphere a fluorine-free low-oxygen gas comprising less than about 20% O.sub.2, by volume. Once the carbonaceous material is sufficiently released, the second phase involves conventionally firing the green body for a time and a temperature sufficient to initiate and sufficiently achieve the conversion of the green ceramic honeycomb structural body into a fired honeycomb body.

Abstract: A sintered ceramic material for high speed machining of heat resistant alloys is provided comprising SiAlON grains and 0.2-20 v/o intergranular phase. At least 80 v/o of said SiAlON phase is beta SiAlON having a z-value greater than 1.0, but less than 1.5. The ceramic material has a Vickers Hardness HV1 of more than 1530 and it is produced by gas pressure sintering.

Abstract: A controlled dielectric loss, sintered aluminum nitride body having a density of greater than about 95% theoretical, a thermal conductivity of greater than about 100 W/m-K, and a dissipation factor measured at room temperature at about 1 KHz selected from:(a) less than or equal to about 0.001; and(b) greater than or equal to about 0.01.A process for producing a controlled dielectric loss, sintered aluminum nitride body, comprising heat treating an aluminum nitride body at sintering temperatures, including providing a heat treatment atmosphere which effects a selected nitrogen vacancy population in the aluminum nitride body at the sintering temperatures, and cooling the aluminum nitride body from sintering temperatures at a controlled rate and in a cooling atmosphere effective to control the selected nitrogen vacancy population.

Abstract: A hot press method for the fabrication of doped or undoped gallium nitride compacts, and of other nitride compacts, employs as a starting material a powder mixture of the selected nitride and of a nitrogen rich salt. A preferred method for fabricating gallium nitride compacts employs ammonium carbonate powder as a starting material additive. In the course of the hot press operation, the endothermic volatilization of ammonium carbonate at a temperature below the disassociation temperature threshold of gallium nitride acts to cool the gallium nitride and also releases free nitrogen radicals that are available to replace any nitrogen lost by gallium nitride molecules through disassociation. The resulting compacts are substantially free of gallium metal, voids, or contaminants, and have a density exceeding 75% of theoretical maximum density.

Abstract: Sintered reaction-bonded silicon nitride components, e.g., automotive components, are made by forming a powder mixture comprising silicon and oxide or oxide precursor additives. These additives comprise alumina and a calcium compound. The powder is formed into a preform, the silicon is reacted with nitrogen in a nitriding process to form silicon nitride, and the so-formed silicon nitride is sintered.

Abstract: A process for the production of a silicon nitride sintered body which comprises heat-treating a stock of silicon nitride sintered body within a temperature range of from the temperature at which the internal friction of the stock exhibits a peculiar peak maximum minus 150.degree. C. to that plus 150.degree. C. A representative used in the process is one which is produced by mixing powdered silicon nitride with powdery sintering aids so as to give a powder mixture comprising 5 to 15% by weight (in terms of oxide) of at least one element selected from the group consisting of rare earth elements and aluminum, 0.5 to 5% by weight (in terms of oxide) of at least one element selected from the group consisting of Mg, Ti and Ca and the balance of Si.sub.3 N.sub.4, molding the powder mixture, and sintering the resulting compact in a nitrogen-containing atmosphere at 1500.degree. to 1700.degree. C.

Abstract: A silicon nitride ceramic of the present invention possesses excellent strength of the surface, including a silicon nitride and a rare earth oxide compound and being characterized in that the ratio of the transverse rupture strength, at a room temperature, of the fired surface used as a tensile surface to the transverse rupture strength, at a room temperature, of the worked surface used as a tensile surface subjected to the working so as to have the surface roughness of R.sub.MAX 0.8 .mu.m or less is 0.7 or more, and the strength ratio is satisfied even when any portion besides the fired surface is utilized as the tensile surface to be worked to have the surface roughness of R.sub.MAX 0.8 .mu.m or less. The present invention also provides a process for producing a silicon nitride ceramic including the steps of: (1) mixing .alpha.-Si.sub.3 N.sub.4 powder and .beta.-Si.sub.3 N.sub.4 powder to obtain a raw material powder so as to satisfy the formula indicated by 0.05.ltoreq..beta./.alpha.+.beta..ltoreq.0.

Abstract: A high-porosity and high-strength porous silicon nitride body comprises columnar silicon nitride grains and an oxide bond phase containing 2 to 15 wt. %, in terms of oxide based on silicon nitride, of at least one rare earth element, and has an SiO.sub.2 /(SiO.sub.2 +rare earth element oxide) weight ratio of 0.012 to 0.65 and an average pore size of at most 3.5 .mu.m. The porous silicon nitride body is produced by compacting comprising a silicon nitride powder, 2 to 15 wt. %, in terms of oxide based on silicon nitride, of at least one rare earth element, and an organic binder while controlling the oxygen content and carbon content of said compact; and sintering said compact in an atmosphere comprising nitrogen at 1,650.degree. to 2,200.degree. C. to obtain a porous body having a three-dimensionally entangled structure made up of columnar silicon nitride grains and an oxide bond phase, and having an SiO.sub.2 /(SiO.sub.2 +rare earth element oxide) weight ratio of 0.012 to 0.65.

Abstract: A sintered silicon nitride-based body comprising 20% or less by weight of a grain boundary phase and the balance being a major phase of grains of silicon nitride and/or sialon, wherein the major phase contains a grain phase of a .beta.-Si.sub.3 N.sub.4 phase and/or a .beta.'-sialon phase, and a quantitative ratio of the grain phase of the .beta.-Si.sub.3 N.sub.4 phase and/or the .beta.'-sialon phase is in a range of 0.5 to 1.0 relative to the major phase; the grain boundary phase contains Re.sub.2 Si.sub.2 O.sub.7 (wherein Re represents a rare-earth element other than Er and Yb) as a first crystal component and at least one of ReSiNO.sub.2, Re.sub.3 Al.sub.5 O.sub.12, ReAlO.sub.3, and Si.sub.3 N.sub.4.Y.sub.2 O.sub.3 as a second crystal component; and a quantitative ratio of the first and second crystal components in the grain boundary phase to the grain phase of .beta.-Si.sub.3 N.sub.4 phase and/or the .beta.'-sialon phase ranges from 0.03 to 1.6.

Abstract: In order to produce a ceramic heater for an oxygen sensor, a method is used, which comprises the steps of: (a) molding a green cylindrical object from a ceramic material which contains a binder; (b) provisionally baking the green cylindrical object at a relatively lower temperature thereby to produce an insufficiently baked cylindrical object, the lower temperature being sufficient for removing the binder from the cylindrical object; (c) printing a heater pattern on a cylindrical surface of the insufficiently baked cylindrical object, the heater pattern being constructed of an electrically conductive material; (d) coating the printed cylindrical surface of the insufficiently baked cylindrical object with a green protection layer thereby to produce a layer-coated cylindrical object; and (e) baking said layer-coated cylindrical object at a relatively higher temperature sufficient for baking the insufficiently baked cylindrical object, the heater pattern and the green protection layer.

Abstract: A method of making a shaped part of sintered silicon nitride is disclosed which includes preparing a mixture of Si.sub.3 N.sub.4 having a BET specific surface area in the range of from 2 to 15 m.sup.2 /g, having an O.sub.2 content of <1.5% by weight, a .beta.-form content of <2% by volume with finely divided Y.sub.2 O.sub.3, Al.sub.2 O.sub.3 or HfO.sub.2 and/or ZrO.sub.2, the total additive content being in the range of from 6 to 13% by weight, based on the total weight of the mixture, then mixing and milling mixture in a liquid dispersion medium, drying and agglomerating the suspension so produced, subsequently pressing, injection molding or redispersing and casting the agglomerated material obtained to make shaped parts, and finally sintering the shaped parts at temperatures between 1725.degree. and 1850.degree. C. under nitrogen for a period of up to 2 hours. The shaped parts produced according to the method have high mechanical strength and include at least 87% by weight Si.sub.3 N.sub.

Abstract: A process of producing high density articles of boron carbide and all transition metal carbides that optionally contain 1 to 50% by volume of borides is disclosed. The process involves the steps of homogeneously mixing boron carbide, titanium oxide and carbon powders, or homogeneously mixing transition metal carbide with its oxide, boron carbide and carbon when sintering transition metal carbides, forming the powder mixtures into a shaped green body, and sintering the body in a controlled atmosphere at a temperature of from 1900.degree. C. to 2100.degree. C. The shaped articles thus obtained have the theoretical density of at least 95% and preferably greater than 99% of theoretical density of selected composite and flexural strength of at least 350 MPa, preferably grater than 450 MPa.

Abstract: A process for the production of refractory materials containing SiALON and carbon or SiALON/SiC and carbon. The process for producing a refractory material containing SiALON and carbon includes heating a molding containing silicon, aluminum, aluminum oxide and carbon to a temperature of 1380.degree. C. at a total atmospheric pressure of less than or equal to 0.1 MPa in an atmosphere containing predominantly nitrogen and containing a concentration of 0 to 5 vol. % of carbon monoxide, subsequently increasing the concentration of carbon monoxide to between 10 and 30 vol. % and heating the molding to a temperature of 1500.degree. C. at a total atmospheric pressure of less than or equal to 0.1 MPa; and subsequently controlling the concentration of carbon monoxide to be between 0 and 10 vol. % and heating the molding to a temperature of 2200.degree. C. at a total atmospheric pressure of greater than or equal to 0.1 MPa.

Abstract: An oxide ceramic sintered body of a single component having a purity of at least 99% by weight of titania and a surface with a plurality of pores therein not exceeding 100 pores per square millimeter. The sintered ceramic body is made by preparing a raw titania powder having a purity of at least 99% titania by weight and an average maximum particle diameter of 1 .mu.m, compacting the titania powder to produce a compact, sintering the compact at a temperature in the range of about 1000.degree. C. to about 1300.degree. under ordinary pressure in air, or an inert or reducing atmosphere. The sintered ceramic body may be hot isostatic pressure treated below the sintering temperature in an inert atmosphere under a pressure of at least 500 kg/cm.sup.2 to further reduce the number of pores in the surface.

Abstract: A composite and pressureless sintering process for making whisker-reinforced alumina composites using about 1 to about 7.5 wt. % of a nitride modifier consisting essentially of silicon nitride, aluminum nitride, or mixtures thereof that produces a sintered body having a density of greater than 95% theoretical.

Abstract: A composite ceramic block gauge is formed from a tungsten carbide (WC) reinforced phase and a chromium carbide (Cr.sub.3 C.sub.2) matrix. The finished block gauge possesses excellent properties such as hardness and corrosion resistance and high reflectivity. The block gauges made from Cr.sub.3 C.sub.2 /WC composites can be calibrated using the traditional optical interferometry techniques.

Abstract: A ceramic heater and a method for producing the ceramic heater. The ceramic heater includes a ceramic heater core formed in a rod shape having a bore extending axially through the heater core. The heater core has a pair of flattened portion near the rear end of the heater core. A conductive heater pattern is formed on the outer peripheral surface of the heater core. The heater pattern includes end portions formed on the respective flattened portions. The ceramic heater also includes a protective layer formed to cover the heater pattern except for the end portions, and flattened conductive terminals formed on the respective end patterns.