Abstract: Dry milling an alpha alumina precursor produces direct conversion to alpha alumina at room temperature.

Abstract: Disclosed is a sintered aluminum nitride composition and a circuit substrate for use in semiconductor device. The sintered aluminum nitride composition comprises: aluminum nitride; a first component given by a compound containing an element which is selected from the group consisting of alkaline earth elements and group IIIa elements of the periodic table; a second component made of either a simple silicon or a silicon-containig compound; and a third component made of either a simple manganese or a manganese-containing compound. The circuit substrate has an insulating layer which is compoesd of the above-described sintered aluminum nitride composition, and an electrically conductive layer containing an electrically conductive material and the same components as those of the insulating layer.

Abstract: A ceramic composition for thermistor exhibiting stable resistance values over a wide temperature range and capable of being used for a prolonged time. The composition is represented by (M.sup.1 M.sup.2 O.sub.3).sub.1-x .multidot.(M.sup.1 AlO.sub.3).sub.x, wherein M.sup.1 is an element selected from the elements of the group 3A excluding La and M.sup.2 is an element of the groups 4A, 5A, 6A, 7A and 8, and wherein the mixing ratio between an electrically conductive substance stable at elevated temperatures and an insulating substance stable at elevated temperatures, may be adjusted. A thermistor formed of the composition is superior in high-temperature stability and can be used over a broad temperature range because its resistance value can be selected to an optimum value.

Abstract: Fused alumina particles are covered with a coating of aluminum titanate which is formed by applying a Ti-containing compound to the surface of the fused alumina particles and firing the same to cause a reaction between the Ti-containing compound and the alumina.

Abstract: An optically translucent polycrystalline alumina sintered body consists essentially of alumina, magnesia, terbia and, optionally, yttria. The magnesia is present in an amount of about 0.020 wgt. percent and the terbia is present in an amount of from about 0.005 to 0.060 wgt. percent. The yttria is present in an amount up to about 0.035 wgt. percent.

Abstract: A sintered, translucent ceramic article comprises alpha alumina and up to 0.050 wgt. percent magnesia and between 0.001 to 0.100 wgt. percent lutetium oxide. In a preferred embodiment, the lutetium oxide is at 0.050 wgt. percent and in a second preferred embodiment half the lutetium oxide is replaced by yttrium oxide. A method of making a translucent ceramic article comprises the steps of: forming an aqueous slurry to yield one of the composition described above; adding nitric acid to adjust the pH to 4.6; adding an aqueous binder and plasticizer in the amount of 2.5 solids wgt. percent; spray-drying the slurry; forming an article by wet-bag isopressing; prefiring said article in air at about 1325.degree. C. for about 2 hours; and sintering said air-fired article in hydrogen for about 3 hours at 1800.degree. C.

Abstract: A ceramic discharge vessel (6) for a high-pressure discharge lamp (1) made from a sintered body of optically translucent polycrystalline alumina ceramic which is doped with only 100-800 ppm MgO, only 200-1200 ppm ZrO.sub.2 and only 10-300 ppm Y.sub.2 O.sub.3 (by weight). This improves the loading capacity and operating characteristics of the vessel and of the lamp.

Abstract: According to this invention, there is disclosed a thermal conductivity substrate which includes an aluminum nitride sintered body and a coating layer formed on the body of aluminum phosphate and having a surface roughness of 1 .mu.m or less, and which has excellent humidity resistance and chemical resistance.

Abstract: A mixture of calcinated metallic oxides are mixed with ZnO and SiO.sub.2, granulated, compacted and then sintered to form a nonlinear resistor. After sintering, the formed ZnO resistor elements are heat treated, preferably in a two-step heat treating process.

Abstract: Ceramic preforms comprising monocrystalline hexagonal platelets of .alpha.-alumina, well adopted for conversion into refractory bricks or ceramic composites, are prepared by crystallizing a settled fine powder of amorphous alumina, transition alumina or alumina hydrate, advantageously in the presence of a fluoro-compound flux, into a coherent mass of such hexagonal platelets of .alpha.-alumina.

Abstract: A beta-alumina solid electrolyte for use in a sodium-sulfur battery is composed of beta-alumina crystals having a degree of orientation toward the C axis thereof, of 0.2-0.4 and an aspect ratio of 4.0 or less. The beta-alumina solid electrolyte is composed of the beta-alumina crystals having a degree of orientation toward the C axis thereof, of 0.2-0.4 and has such a particle diameter distribution that the average particle diameter is 3 .mu.m or less, the proportion of the particles having a particle diameter of 5 .mu.m or less is 90% or more, and the maximum particle diameter is 300 .mu.m or less. A process for producing a beta-alumina solid electrolyte using an alumina source material, a magnesium source material and a sodium source material, uses a magnesium-aluminum spinel as the magnesium source material and subjects all materials to mixing, granulation, molding and firing to obtain a beta-alumina solid electrolyte without subjecting the materials to calcination.

Abstract: An alpha alumina-based ceramic abrasive grain comprising, on a theoretical oxide basis, Al.sub.2 O.sub.3, Fe.sub.2 O.sub.3, and SiO.sub.2. The abrasive grain has a surface roughness height of greater than about 200 nanometers and a density of greater than about 3.50 g/cm.sup.3. Preferably, the alpha alumina-based ceramic abrasive grain has alpha alumina crystallites having an average crystallite size of less than about 0.5 micrometer (more preferably, less than about 0.3 micrometer). The presence of the SiO.sub.2 in combination with Fe.sub.2 O.sub.3 increases the amount of transgranular fracture of the abrasive grain, reduces the alpha alumina crystallite growth during sintering of the abrasive grain, dilates at least one of the unit cell dimensions of the abrasive grain, and generally improves the grinding performance of the abrasive grain.

Abstract: An inorganic composition comprises (A) 60 to 99% by weight of spherical inorganic oxide particles having a mean particle diameter greater than 0.1 .mu.m but not greater than 1 .mu.m, and (B) 40 to 1% by weight of inorganic oxide fine particles having a mean particle diameter not greater than 0.1 .mu.m, wherein a volume of micro pores due to strongly aggregated particles having pore diameters not smaller than 0.08 .mu.m is not greater than 0.1 cc per gram of the inorganic composition. The inorganic composition, when mixed with a polymerizable monomer and a catalyst, provides a composite useful for dental applications which has excellent surface smoothness, can be polished in a short time, exhibits improved bending strength, compressive strength, surface hardness and wear resistance and causes little wear on an antagonistic tooth.

Abstract: A low thermal expansion cordierite aggregate, which consists mainly of cordierite crystals having a mean crystal diameter of at least 50 .mu.m and has little orientation in the crystal structure, shows hysteresis in its thermal expansion property accompanying a rise and fall of the temperature, and has a mean thermal expansion coefficient within a temperature range of from room temperature to 1000.degree. C. of at most 10.times.10.sup.-7 /.degree.C.

Abstract: The present invention provides a method for preparing a ceramic mixed-oxide of at least two metals including mixing an alloy with a ceramic oxide. The alloy including a metal selected from the group consisting of aluminum, calcium, lithium, magnesium, silicon, titanium, yttrium, and zirconium. The alloy also includes an element that is to be present in the ceramic mixed-oxide. The element is different from the metal and is selected from the group consisting of aluminum, calcium, lithium, magnesium, a combination of magnesium and silicon, silicon, titanium, yttrium, and zirconium. The ceramic oxide includes a metal that is to be present in the ceramic mixed oxide. The alloy and ceramic oxide are co-milled. The mixed and co-milled alloy and ceramic oxide are reaction-sintered, thereby oxidizing the metal and element of the alloy to produce the ceramic mixed-oxide.

Abstract: Crystalline ceramic, alpha alumina-based abrasive grain and a method of making the same. The abrasive grain can be incorporated into abrasive products such as coated abrasives, bonded wheels, and three dimensional, low density abrasives.

Abstract: In the method described, the degree of agglomeration of the nanometer-size particles can be readily checked, thus enabling dispersions of particles of this kind to be produced with high solids contents. The method calls for the unmodified powder to be dispersed in water and/or an organic solvent in the presence of a low-molecular organic compound including a functional group which can react and/or interact with groups present on the surface of the powder particles. The dispersant may subsequently be wholly or partly removed.

Abstract: An object of the present invention is to shorten the working time for high pressure slip casting. There is provided a composition for high pressure casting slip including a first starting powder forming a frame of a mold body and second starting powder forming the frame of the mold body and acting as a plastic agent, wherein the first and second starting powders are uniformly mixed in a dry condition. "Slip" of a minimum water content is easily prepared by the composition to effect optimal fluidity of the slip so that the water is removed from the slip in a short time during a casting process.

Abstract: A sintered, translucent ceramic article comprises alpha alumina and up to 0.050 wgt. percent magnesia and between 0.001 to 0.100 wgt. percent lutetium oxide. In a preferred embodiment, the lutetium oxide is at 0.050 wgt. percent and in a second preferred embodiment half the lutetium oxide is replaced by yttrium oxide. A method of making a translucent ceramic article comprises the steps of: forming an aqueous slurry to yield one of the composition described above; adding nitric acid to adjust the pH to 4.6; adding an aqueous binder and plasticizer in the amount of 2.5 solids wgt. percent; spray-drying the slurry; forming an article by wet-bag isopressing; prefiring said article in air at about 1325.degree. C. for about 2 hours; and sintering said air-fired article in hydrogen for about 3 hours at 1800.degree. C.

Abstract: The present invention provides a process for producing fine flaky alumina particles suitable as a raw material for ceramics, a pigment for paint and etc., wherein aluminum hydroxide or alumina hydrate having a particle size regulated to the order of submicron is subjected to a hydrothermal treatment in water or an aqueous alkali solution at a temperature of 350.degree. C. or above under a pressure of 200 kg/cm.sup.2 or below. The present invention further provides an alumina-based plastic material which is produced by kneading the aforesaid fine flaky particles with an organic water holding material and water. Methylcellulose, polyvinyl alcohol, carboxymethylcellulose, polyethylene glycol, etc. are preferably used as the organic water holding agent. The alumina-based plastic material has a high plasticity, so that there is no need of using a large amount of a binder. Thus a dense molded article having stable properties can be prepared.

Abstract: Ultraviolet (UV) radiation in the UV-C and UV-B bands, which is particularly dangerous, is absorbed and filtered by quartz glass doped with between 0.065% and 3.25%, and preferably between 0.065% and 1.3% by weight, of cerium metal, or cerium as such. Preferably, the cerium is added to quartz sand and/or rock crystal, in form of a fine-grained powder of up to 2 0 .mu.m grain size, in form of cerium aluminate (CeAlO.sub.3), present in up to about 5% by weight, and preferably up to about 2%, and melted together in a single step. The quartz glass so obtained is particularly suitable for a metal halide discharge lamp, e.g. as an outer envelope (1), or as the discharge vessel (27) itself, or for halogen incandescent lamps, to form the quartz-glass light bulb or an envelope therefor. A small quantity of titanium oxide, up to about 0.05%, may be added as a further doping agent to the melt to further improve the UV absorption in the B and C bands.

Abstract: Cordierite honeycomb ceramics comprises a cordierite phase as a main ingredient. A value of [Fe.sub.2 O.sub.3 wt %/(MgO wt %+Fe.sub.2 O.sub.3 wt %)].times.100 is 2-10, where a ferric component is calculated as Fe.sub.2 O.sub.3. A thermal expansion coefficient of the cordierite honeycomb ceramics is less than 0.5.times.10.sup.-6 /.degree. C. within a temperature range of 40.degree.-800.degree. C. in a direction parallel to a flow passage of a honeycomb body. In the cordierite honeycomb ceramics including a ferric component, a ferric component is added from a talc as raw materials. The cordierite honeycomb ceramics having a low thermal expansion coefficient is obtained by mixing raw materials for cordierite generation to obtain a batch, extruding the batch into a honeycomb formed body, drying the honeycomb formed body, and firing the dried honeycomb formed body at a temperature range of 1350.degree.-1450.degree. C. After that, the sintered honeycomb body is immersed in an acid solution if necessary.

Abstract: A barrier comprising:a) between about 75 w/o and about 95 w/o alumina-silica refractory grain, andb) between about 2 w/o and about 10 w/o of a sealant selected from the group consisting of zinc borate; sulfur; R1 Al.sub.x/2 Si.sub.y/2 O.sub.z/2 and R2 Si.sub.b/2 S.sub.c/2 C.sub.d/2 O.sub.e/2 H.sub.f/2 wherein:i) R1 is selected from the group consisting of Na, K, and Li, and mixtures thereof,ii) x,y and z are integers between 0 and 16,iii) R2 is selected from the group consisting of Ca, Sr and Mg, and mixtures thereof, andiv) b,c,d,e and f are integers between about 0 and 16.

Abstract: The present invention relates to boron subphosphide/aluminum oxide composite materials, to processes for the production of these materials and to the use thereof.

Abstract: A low thermal expansion cordierite aggregate, which consists mainly of cordierite crystals having a mean crystal diameter of at least 50 .mu.m and has little orientation in the crystal structure, shows hysteresis in its thermal expansion property accompanying a rise and fall of the temperature, and has a mean thermal expansion coefficient within a temperature range of from room temperature to 1000.degree. C. of at most 10.times.10.sup.-7 /.degree.C.

Abstract: Alpha alumina-based abrasive grain having an as sintered outer surface. The abrasive grain can be incorporated into abrasive articles such as bonded abrasives (e.g., grinding wheels), coated abrasives, and nonwoven abrasives.

Abstract: An aluminum nitride ceramic having desired properties suitable for electronic packaging applications can be prepared from a novel aluminum nitride powder/sintering aid mixture. The sintering aid comprises a glassy component formed from alumina, calcia and boria, and a non-vitreous component comprising an element or compound of a metal of Group IIa, IIIa, or the lanthanides, preferably crystalline oxides, reactibis with the crystallized glass component and the alumina from the Al N grains. Alternatively, the sintering aid comprises a multi-component glass composition capable of forming the above components upon melting and thereafter crystallizing upon reaction.

Abstract: A lapping composition which contains abrasive grains which are commercially available and which consists of plate alumina-powder prepared by milling and class:trying a sintered body of plate alumina obtained by calcinating aluminum hydroxide, and other plate alumina powder classified and prepared separately from but similarly to the first-mentioned plate alumina powder having average grain size which is in a range of from 1.3 times to 2.3 times as large as the average grain size of the first-mentioned plate alumina powder. Further provided is a lapping method with such a lapping composition by which the removal rate is improved and a lapped surface excellent in quality can be obtained.

Abstract: The invention provides a method of making a magnesium/aluminium spinel compound having the formula Mg.sub.(1+x) Al.sub.(2+y) O.sub.4 in which 0.ltoreq.x.ltoreq.0.2 and 0.ltoreq.y.ltoreq.0.35. Particulate aluminium metal and a magnesium-containing component selected from magnesium oxide and precursors thereof are mixed together and heated to 800.degree.-1150.degree. C. in an oxidising environment to cause oxidation of at least part of the aluminium. Further heating then takes place to a temperature of 1150.degree.-1350.degree. C. in the oxidizing environment to cause aluminium oxide and magnesium oxide in the admixture to react together.

Abstract: An Al.sub.2 O.sub.3 -TiC sintered product comprising Al.sub.2 O.sub.3 as a main component and containing TiC in an amount of from 20 to 40% by weight, wherein the average particle diameter of Al.sub.2 O.sub.3 particles in the sintered product is larger by 5 to 50% than the average particle diameter of TiC particles, the average particle diameter of the sintered product as a whole is not larger than 1 .mu.m, the average particle diameter of TiC particles is not larger than 0.9 .mu.m, and the total amount of the grain boundary phases other than Al.sub.2 O.sub.3 and TiC is not larger than 1.0% by weight. The Al.sub.2 O.sub.3 -TiC sintered product can be used as a substrate 1 for a magnetic head, and has portions such as grooves 4 and stepped portions formed in the surface of the air bearing surface 2 of the slider by being irradiated with ions. The sintered product exhibits excellent surface quality after machined by being irradiated with ions and can be machined at an increased rate.

Abstract: A method of making a .beta.-alumina compound which is a polyaluminate of the general formula M.sub.y O.multidot.xAl.sub.2 O.sub.3 in which M is a metal selected from monovalent metals and divalent metals, y=2 when M is a monovalent metal, y=1 when M is a divalent metal and x=4-12 comprises forming a green precursor of the 62 -alumina compound by mixing together particulate aluminium metal and a reagent compound comprising an oxide of the metal M or a precursor thereof. The mixture is heated to 800.degree.-1150.degree. C. in an oxidizing environment to cause oxidation of at least part of the aluminium. Further heating then takes place to 1150.degree.-1350.degree. C. in said environment to cause the oxidized aluminium and oxide of the metal M to react to form the .beta.-alumina compound.

Abstract: The invention relates to a densely sintered tabular ceramic part of aluminum oxide having improved thermal shock resistance, which possesses a fine porosity of at most 10% by volume, does not contain inclusions having a diameter of .gtoreq.70 .mu.m within the ceramic microstructure and is not destroyed on immersion in a molten metal bath having a temperature of at least 350.degree. C. The invention also relates to a process for producing such a shaped part.

Abstract: Seeded sol-gel alumina abrasive grits with improved grinding performance incorporating alkali metal oxides selected from rubidium and cesium oxides.

Abstract: Alpha alumina-based abrasive grain including aluminate platelets. The abrasive grain can be incorporated into abrasive articles such as bonded abrasives (e.g., grinding wheels), coated abrasives, and nonwoven abrasives.

Abstract: The present invention is directed to a solid electrolyte and a process for making the same for a sodium-sulfur secondary cell including a composition of 7.0 to 10.0 weight percent of Na.sub.2 O, 0.5 to 3.5 weight percent of MgO or 0.7 to 1.0 weight percent of Li.sub.2 O, 0.01 to 0.6 weight percent of WO.sub.3, and the balance of Al.sub.2 O.sub.3. The solid electrolyte is prepared by mixing Na.sub.2 O, MgO, Li.sub.2 O, WO.sub.3, and Al.sub.2 O.sub.3, calcining the resulting mixture, pulverizing the calcined body, and subjecting the resulting powders to sintering. Alternatively, the solid electrolyte is prepared by mixing Na.sub.2 O, MgO, or Li.sub.2 O, and Al.sub.2 O.sub.3 with one another, calcining the mixture, adding WO.sub.3 to the calcined body, pulverizing the resulting material, and subjecting the resulting powders to sintering.

Abstract: A method of forming a ceramic having a smooth ceramic surface and an assembly for forming ceramics having a flat and smooth ceramic surface are disclosed. A greenware precursor is disposed between a greenware base and a greenware cover. A frame is disposed between the greenware base and greenware cover for limiting compression of the greenware article to an amount which allows formation of a smooth ceramic surface during densification of the greenware precursor. The greenware base, greenware cover and greenware precursor are densified to cause the greenware precursor to form a ceramic having a smooth ceramic surface.

Abstract: Novel aluminum phosphates, in particular amorphous aluminum phosphate powders having a BET specific surface no greater than 25 m.sup.2 /g, well suited as binders/hardeners or for the production of ceramic shaped articles, are prepared by reacting at least one aluminum compound, e.g., an aluminum oxide, hydroxide or oxyhydroxide, with phosphoric acid or an aluminum phosphate, e.g., an acid aluminum orthophosphate, in a liquid reaction medium devoid of inorganic acid anions other than of phosphoric acid, and then spray- or freeze-drying the suspension thus obtained.

Abstract: Transparent, polycrystalline garnet bodies having desirable properties for use as laser material, luminescent x-ray scintillator materials and other uses are produced by mixing a chloride source solution of the desired cations with a basic ammonium solution to produce a precipitate having a substantially uniform composition which can be further processed to provide the desired transparent body. This precipitate is separated from the solution, dried, thermally decomposed at a temperature in the range from 700.degree. to 1,000.degree. C., pressed to form a compact, isostatically pressed at up to 60,000 psi to provide a green, unsintered compact having a density in the vicinity of 55% of theoretic density. That green compact is then sintered in oxygen at a temperature between 1,400.degree. and 1,700.degree. C. to produce the desired transparent body. Alternatively, the compact may be sintered in oxygen at temperatures in the range from about 1,400.degree. to about 1,600.degree. C.

Abstract: A novel ceramic composite material consisting of single crystal .alpha.-Al.sub.2 O.sub.3 and polycrystal Y.sub.3 Al.sub.5 O.sub.12 and a ceramic composite material consisting of polycrystal .alpha.-Al.sub.2 O.sub.3 and polycrystal Y.sub.3 Al.sub.5 O.sub.12, each having a high mechanical strength and creep behavior particularly at high temperature are provided.

Abstract: A ceramic composite contains one spinel phase and one or more than one oxides phases. The composite is derived from the mixtures of two oxides, A.sub.2 O.sub.3 and BO, with different molar ratio, in which A and B are metallic ions of three and two valences respectively. The oxides are heated at a high temperature to form a composite containing a spinel and residual oxides. The formed spinel and residual oxides also undergo densification under high temperature. After the treatment at high temperature, not only the spinel is formed but also the composite is densified. The performance of the composite is superior in its strength, toughness and high-temperature stability.

Abstract: An unsintered aluminum nitride body including:(a) 1 to 5 weight percent of a vitreous solid of boria, alumina, and calcia in the proportions of (1) boria between 3 and 25 weight percent, (2) alumina between 10 and 50 weight percent, and (3) calcia between 40 and 80 weight percent; and(b) aluminum nitride powder as the balance of the aluminum nitride body.

Abstract: A ceramic composition for thermistor exhibiting stable resistance values over a wide temperature range and capable of being used for a prolonged time. The composition is represented by (M.sup.1 M.sup.2 O.sub.3).sub.1-x .multidot.(M.sup.1 AlO.sub.3).sub.x, wherein M.sup.1 is an element selected from the elements of the group 3A of the International Periodic Table excluding La and M.sup.2 is an element of the groups 4A, 5A, 6A, 7A and 8 of the International Periodic Table, and wherein the mixing ratio between an electrically conductive substance stable at elevated temperatures and an insulating substance stable at elevated temperatures, may be adjusted. A thermistor formed of the composition is superior in high-temperature stability and can be used over a broad temperature range because its resistance value can be selected to an optimum value.

Abstract: The present invention provides a process for the production of a K- or Rb-.beta."- or -.beta.-aluminum oxide powder preparation, wherein a cubic densely packed aluminum oxide (.gamma.-aluminum oxide) or a precursor thereof is subjected to attrition together with a doping material or a precursor thereof, the so obtained mixture is calcined in an oxygen-containing atmosphere, potassium oxide or rubidium oxide or a precursor of these compounds is added to the calcination product obtained, the mixture is subjected to attrition and then calcined in an oxygen-containing atmosphere at a temperature greater than 900.degree. C. The present invention also provides a process for the production of a ceramic formed body in which a powder obtained by the above process is converted by attrition, isostatic pressing and sintering into a ceramic formed body. Such a ceramic formed body can be used as an ion conductor.

Abstract: A slurry for joining metallic or ceramic surfaces or for coating metallic or ceramic and refractory surfaces, comprising a liquid suspending medium and at least two constituents in particulate form suspended in the medium, the constituents being so selected and proportioned as to undergo combustion synthesis when ignited. A method for coating or joining metallic or ceramic surfaces comprises applying such a slurry to a surface to be coated or to surfaces to be joined, and igniting the slurry to cause combustion synthesis.

Abstract: Ultraviolet (UV) radiation in the UV-C and UV-B bands, which is particularly dangerous, is absorbed and filtered by quartz glass doped with between 0.065% and 3.25%, and preferably between 0.065% and 1.3%, by weight, of cerium metal, or cerium as such. Preferably, the cerium is added to quartz sand and/or rock crystal, in form of a fine-grained powder of up to 20 .mu.m grain size, in form of cerium aluminate (CeAlO.sub.3), present in up to about 5% by weight, and preferably up to about 2%, by weight, and melted together in a single step. The quartz glass so obtained is particularly suitable for a metal halide discharge lamp, e.g. as an outer envelope (1), or as the discharge vessel (27) itself, or for halogen incandescent lamps, to form the quartz-glass light bulb or an envelope therefor. A small quantity of titanium oxide, up to about 0.05%, may be added as a further doping agent to the melt to further improve the UV absorption in the B and C bands.

Abstract: The invention relates to nano-composite powders of alumina and metal constituted of grains of micronic size. Each grain comprises a compact matrix of alumina of a specific surface area less than 5 m.sup.2 /g, in which are dispersed crystallites of transition metals of alloys of these metals, of sizes less than 50 nm. The powder according to the invention may be produced starting with a precursor comprised of a mixed carboxylic salt of aluminum and one or more transition metals. The powders according to the invention permit producing by sintering cermets of alumina/metal benefitting from greatly improved mechanical and thermo-mechanical properties.

Abstract: A porcelain having 9 to 55% by weight of SiO.sub.2, 36 to 87% by weight of Al.sub.2 O.sub.3, 0 to 2.0% by weight of Fe.sub.2 O.sub.3, 0 to 1.0% by weight of TiO.sub.2, 0 to 0.5% by weight of CaO, 0 to 0.5% by weight of MgO, 1.0 to 4.0% by weight of K.sub.2 O and Na.sub.2 O combined, and 0.25 to 25.0% by weight of bismuth oxide is disclosed. The porcelain has unexpectedly high unglazed bending strength and may be used for dielectric and structural applications.

Abstract: A sinterable aluminum nitride powder composition is prepared by adding about 0.05-10.0 parts by weight of at least one compound selected from the group consisting of calcium tungstate and calcium molybdate and optionally about 1.0-7.0 parts by weight of at least one compound selected from the group consisting of yttria, calcium oxide, and calcium carbonate to 100 parts by weight of an aluminum nitride powder prepared by the alumina reduction method without decarbonization and having a residual carbon content of about 2%-10% by weight. The resulting powdery composition is subjected to mixing and deagglomeration in a dry process so as to form a powder mixture having a bulk density of about 0.3-0.5 g/cm.sup.3, and then to decarbonization by heating in an oxidizing atmosphere. The aluminum nitride powder composition has a pressurized bulk density of about 1.50-1.75 g/cm.sup.3 as measured at a pressure of 500 kg/cm.sup.2 and an average particle diameter of about 1.0-3.0 .mu.

Abstract: The present invention relates to a ceramic cutting insert containing whiskers for chip forming machining of steel and having improved mechanical, thermal and wear properties. The insert comprises besides the oxide-based matrix 5-50% by volume, preferably 10-40% by volume, of homogeneously dispersed whiskers of carbides, nitrides and/or borides of titanium and/or zirconium and, where applicable, solid solutions thereof. A part of the whiskers may be replaced by whiskers of silicon carbide. The properties of the composite material can be further modified by coating the whisker material with thin layers. The whiskers reinforced cutting material shows an improved toughness behaviour and resistance to thermal crack formation without having a negative influence on the wear resistance to any appreciable extent.

Abstract: A transparent composite armor providing complete protection for small arms rojectiles up to and including caliber .50 AP M2 projectiles consisting of two or more layers of transparent material having a hard frangible face plate backed by one or more tough resilient plates to absorb the excess impact force after contact with the face plate, the several plates being bonded together with a suitable transparent adhesive.