Abstract: MoO.sub.2 is used as an accelerant for transformation of zirconia (ZrO.sub.2) from a tetragonal to a monoclinic crystal phase. A ZrO.sub.2 -MoO.sub.2 alloy having an increased content of monoclinic ZrO.sub.2 is prepared by mixing MoO.sub.2 with ZrO.sub.2 followed by heat treatment. In another aspect of the invention, the surface of an alumina-zirconia composite is strengthened by heating the composite in the presence of MoO.sub.2 -ZrO.sub.2 mixed powder.

Abstract: A known relatively dense composite refractory material has a matrix of a refractory material and a dispersed phase in the form of particles of a ceramic material, each dispersed particle comprising an agglomerate of strongly bonded microcrystals, which exhibit strong thermal expansion anisotropy and do not crack spontaneously on cooling from about 1600.degree. C. to ambient temperature. The thermal shock resistance of this composite refractory material is improved by (a) ensuring that the matrix material comprises from 5 to 90 percent by volume of grains having a diameter in the range of from 15 micrometers to about 80 micrometers, and/or (b) including at least one thermal down-quench of from 50.degree. C. to 1500.degree. C. in the final cooling step in the production of the composite refractory material. Alumina is a typical matrix material, with monoclinic zirconia as the dispersed phase.

Abstract: A ceramic cutting insert for high speed machining of materials is provided having an integral chip control surface thereon.

Abstract: The present invention provides a zirconium oxide-containing ceramic formed body, wherein it is also free from amorphous phases on the grain boundaries and triple points, displays a shrinkage of less than 5% in comparison with its green body and is obtainable by reaction sintering of a green body, said ceramic formed body being formed from a mechanically alloyed mixture which contains or consists of at least 1% by volume zirconium metal powder and at least 20% by volume of one or more metallic powders selected from the elements magnesium, aluminum, copper, selenium, titanium, vanadium, chromium, manganese, iron, cobalt, nickel, zinc, strontium, yttrium, niobium, cerium, hafnium and tantalum, as well as the oxides thereof and zirconium oxide, sodium oxide, potassium oxide and lithium oxide.

Abstract: Ceramic abrasive grits are formed by an impregnation process that involves preparing an alumina hydrate sol, drying the sol to form a porous solid, crushing the solid to produce particles, calcining the dried particles, preparing a mixture of an additive metal oxide or its precursor in a liquid vehicle, impregnating the mixture into the calcined particles, drying the impregnated particles, calcining the dried impregnated particles, and firing the particles to produce ceramic abrasive grits. The concentration of the modifying additive metal is greater at or near the surface of the grit than at the interior of the grit.

Abstract: An electrochemical measurement sensor for determining the oxygen content in gases, in particular in exhaust gases from internal combustion engines, having a solid electrolyte of stabilized zirconium dioxide and/or other oxygen ion-conductive oxides and at least one electrode on the side of the solid electrolyte exposed to the gas which is to be measured, is proposed, the electrode or electrodes containing, if desired, a ceramic support structure, and the electrode or electrodes exposed to the gas, which is to be measured, being covered by a porous ceramic protective layer of an Al.sub.2 O.sub.3 and/or Mg spinel (MgO.Al.sub.2 O.sub.3) matrix with preferably metastable ZrO.sub.2 particles incorporated therein.The use of an Al.sub.2 O.sub.3 ZrO.sub.2 mixed oxide, which is preferably obtained by coprecipitation or by combination of suspensions of separately precipitated components or by spray-calcination of a combined solution of salts of the components and which may, if desired, contain a stabilizer for the ZrO.

Abstract: It is disclosed that the properties of a ceramic mullite-kaolinite based passivating coating composition applied as a collar to metal oxide varistor valve block cylindrical surfaces are improved by including in the coating composition from 0.03 to 15% by weight of the coating composition one or more of the following additive compounds: TiO.sub.2 ; Y.sub.2 O.sub.3 ; ZrO.sub.2 ; ZnO; Boroflux (2ZNO.sup.. 3B.sub.2 O.sub.3.sup.. 7H.sub.2 O; or 3ZnO.sup.. 2B.sub.2 O.sub.3.sup.. 5H.sub.2 O); or Si.sub.3 N.sub.4. The coating composition comprises by dry weight a mixture of 55-85% mullite and 15-45% kaolinite, one or a mixture of the above additive compounds, and sufficient water to form a sprayable slurry. The inclusion of the additive compound results in enhanced contact adhesion between the collar and the metal oxide varistor peripheral surface.

Abstract: A relatively dense composite refractory material which has reasonable strength and good thermal shock resistance comprises an alumina matrix material within which are dispersed particles of polycrystalline zirconia comprises from 1.0 to 40 percent by volume of the composite material. Each particle of zirconia is an agglomerate of microcrystals which are strongly bonded together. Due to the agglomerates of the bonding together of the microcrystals at their grain boundaries. The microcrystals contain no matrix material within their agglomerates, and exhibit strong thermal expansion anisotropy. They have a size such that cracks do not form spontaneously within the agglomerates during cooling from about 1600.degree. C. to room temperature. Typically the agglomerates have a mean diameter of from 10 to 15 micrometers, while the average diameter of the microcrystals in an agglomerate is from 1 to 2 micrometers.

Abstract: A sintered body where alumina is dispersed in a zirconia matrix in which yttria has been doped to form a solid solution can be obtained by compacting a mixed powder comprising zirconia or yttria-stabilized zirconia and yttrium-aluminum complex oxide and sintering the resulting compacted body. This sintered body comprises a fine zirconia matrix in which fine alumina particles are dispersed to strengthen it and is excellent in flexural strength and fracture toughness and has a practically effective oxygen ionic conductivity.

Abstract: A non-magnetic substrate material which contains 0.5%-3% of Al.sub.2 O.sub.3 and 3%-16% of at least either ZnO or SnO.sub.2 (but with ZnO+SnO.sub.2 <=16%) in addition to components of 45%-60% of TiO.sub.2, 5%-20% of BaO and 20%-35% of CaO, and a floating-type magnetic head with a slider made of the above-mentioned non-magnetic substrate material.

Abstract: A refractory composition, particularly for application as a dry vibratable refractory for forming the wearable, disposable monolithic lining coating the permanent lining of a tundish or ladle used in molten metal casting processes is disclosed. The composition contains a refractory aggregate, a first bonding agent actuatable at temperatures in the range of from about 300.degree. F. to about 1000.degree. F. to cause the formation of interparticle bonds between aggregate particles, at least one second bonding agent actuatable at temperatures in the range of from about 1000.degree. F. to about 2500.degree. F. to cause further formation of interparticle bonds between aggregate particles, and, optionally, clay. The use of both first and second bonding agents enables installation of the refractory in hot practice, in which vessel preheat temperatures of up to about 2500.degree. F. are utilized.

Abstract: The present invention provides an improved alumina sintered body on which a heater electrode is printed and which is sintered simultaneously with the heater electrode at temperatures lower than the optimum value 1,520.degree. C. The alumina sintered body includes high purity of alumina and 2 through 18% by weight partially stabilized zirconia, which further contains 2 through 6 mole percent solid solution of an oxide or oxides selected from Y.sub.2 O.sub.3, Sc.sub.2 O.sub.3, and lanthanum series metal oxides. The high purity of alumina may contain 0.1% by weight alkaline metals and/or alkaline earth metals and 1.0% by weight SiO.sub.2 at most. In the alumina sintered body of the invention, segregation and migration of impurities and chipping are effectively prevented and hence the durability of the sintered body is highly improved. Use of the alumina sintered body of the invention as a heater base makes the durability of a heater much longer.

Abstract: A refractory ceramic material, including a porous base refractory material and a zirconia protective layer covering walls of pores of the porous base refractory material, wherein the refractory ceramic material has a porosity of not less than 80%, and the zirconia protective layer has a thickness not more than about 1 nanometer.

Abstract: There is disclosed an Al.sub.2 O.sub.3 based ceramic which includes 5% to 50% by weight of a hard dispersed phase of at least one compound selected from metal carbide, metal nitride, metal carbonitride, metal oxy-carbide, metal oxy-nitride and metal carbo-oxy-nitride. The compound is represented by M(CNO), wherein M is at least one metal selected from the group consisting of Ti, Zr and Hf. The ceramic optionally contains 1% to 25% by weight of ZrO.sub.2, and balance Al.sub.2 O.sub.3 matrix, which contains an additive dissolved in the Al.sub.2 O.sub.3 grains so as to form solid solution therewith. The additive is contained in an amount of 0.01% to 12% by weight with respect to the Al.sub.2 O.sub.3 matrix and is at least one oxide of an element selected from the group consisting of Y, Mg, Cr, Ni, Co, and rare earth elements. The Al.sub.2 O.sub.3 grains have an average grain size no larger than 1.0 .mu. m while the hard phase constituent has an average grain size no larger than 0.6 .mu. m.

Abstract: A method of making a ceramic material by radiating a laser beam onto the portion of said ceramic material to be marked in a low oxygen atmosphere and a block gauge marked by this marking method. This marking method enables a ceramic material to have a distinct mark. A block gauge composed of a ceramic material has excellent properties such as corrosion resistance.

Abstract: Green bodies suitable for use in manufacturing ceramic articles are provided. The bodies comprise a coherent mass of particles of aluminium oxide free of organic binder and having a fracture stress measured by a biaxial disc flexure test of at least 10 MPa. The particles of aluminium oxide are coated with at least one inorganic oxide or hydrous oxide.The green body can be shaped by drilling, sawing etc. to a desired shape approximating to that of the ceramic article which it is used to produce. Generally such shaping is considerably easier than shaping the finished ceramic article.

Abstract: Ceramic binder for forming and processing ceramic ware, comprising a sol-gel of a mixture of highly charged metal hydroxy cations and one or more low charged metal hydroxy cations, which are able to form an aqueous sol.

Abstract: A non-magnetic substrate for use in a magnetic head, consists of the basic composition consisting of CoO and NiO or NiO, and (a) from 0.1 to 7% by weight of ZrO.sub.2 and HfO.sub.2 based on 100% of the basic composition, or (b) from 0.1 to 7% by weight of ZrO.sub.2, and from 0.1 to 2% by weight of Al.sub.2 O.sub.3. Cracking of the magnetic-layer structure is prevented.

Abstract: An electrically conductive material for use in solid oxide fuel cells, electrochemical sensors for combustion exhaust, and various other applications possesses increased fracture toughness over available materials, while affording the same electrical conductivity. One embodiment of the sintered electrically conductive material consists essentially of cubic ZrO.sub.2 as a matrix and 6-19 wt. % monoclinic ZrO.sub.2 formed from particles having an average size equal to or greater than about 0.23 microns. Another embodiment of the electrically conductive material consists essentially at cubic ZrO.sub.2 as a matrix and 10-30 wt. % partially stabilized zirconia (PSZ) formed from particles having an average size of approximately 3 microns.

Abstract: An electrical resistive material used for making e.g. a heating element for a thermal printing element. It is a Cr--Al--B--Zr--O alloy and is composed of a quaternary alloy and 15 to 25 at % of oxygen, wherein the quaternary alloy is composed of 2 to 25 at % of zirconium and a ternary alloy containing 35 to 55 at % of chromium, 2 to 23 at % of aluminium and 37 to 58 at % of boron.

Abstract: A refractory composition consisting essentially of, for each 100 wt. % thereof, about 40 to 80 wt. % of an alumina, about 5 to 30 wt. % of a zirconia-containing grain, about 2 to 10 wt. % of a carbon, and about 1 to 12 wt. % of an oxidation and erosion resistance additive, the method of making refractory shapes utilizing such composition, and the resultant shapes.

Abstract: A process is presented for the fabrication of a metal/ceramic composite by a non-vapor phase oxidation of a molten metal by contacting said molten metal at an elevated temperature with a sacrificial ceramic preform. The shape of the preform is retained but the ceramic preform is reduced, oxidizing the molten metal. A preferred sacrificial ceramic preform is silica, but can also be, for example, mullite, titania or zirconia, and the preferred molten metal is aluminum or an aluminum alloy. Thus, for example, is produced from immersing a silica preform into molten aluminum alloy, an Al/Al.sub.2 O.sub.3 composite metal/ceramic article which does not contain silica or silicon and which is extremely tough.

Abstract: It is disclosed that the properties of a ceramic mullite-kaolinite based passivating coating composition applied as a collar to metal oxide varistor valve block cylindrical surfaces are improved by including in the coating composition from 0.03 to 15% by weight of the coating composition one or more of the following additive compounds: TiO.sub.2 ; Y.sub.2 O.sub.3 ; ZrO.sub.2 ; ZnO; Boroflux (2ZnO.multidot.3B.sub.2 O.sub.3 .multidot.7H.sub.2 O; or 3ZnO.multidot.2B.sub.2 O.sub.3 .multidot.5H.sub.2 (O); or Si.sub.3 N.sub.4. The coating composition comprises by dry weight a mixture of 55-85% mullite and 15-45% kaolinite, one or a mixture of the above additive compounds, and sufficient water to form a sprayable slurry. The inclusion of the additive compound results in enhanced contact adhesion between the collar and the metal oxide varistor peripheral surface.

Abstract: A process for preparation of heat-resistant and wear-resistant ceramic material which comprises sintering the material under a non-oxidizing atmosphere until the metal of a component (a) no longer exists as a metallic phase. A starting composition for forming the ceramic material comprises from 1 to 40 wt % of Al.sub.2 O.sub.3, from 0.05 to 8 wt % of sintering assistant, from 3 to 35 wt % total of one or both of ZrO.sub.2 and HfO.sub.2, and from 17 to 95.95 wt % of carbide components (a) and (b), or (a), (b), and (c), wherein component (a) is one or more metals selected from the Groupd IVB, VB, and VIB of the Periodic Table; component (b) is TiC, and component (c) is one or more metal carbides selected from Zr, Hf, and metals of Groups VB and VIB of the Periodic Table.

Abstract: There is disclosed an Al.sub.2 O.sub.3 based ceramic which includes 5% to 50% by weight of a hard dispersed phase of at least one compound selected from metal carbide, metal nitride, metal carbonitride, metal oxy-carbide, metal oxy-nitride and metal carbo-oxy-nitride. The compound is represented by M(CNO), wherein M is at least one metal selected from the group consisting of Ti, Zr and Hf. The ceramic contains no greater than 25% by weight of ZrO.sub.2, and balance Al.sub.2 O.sub.3 matrix. which contains an additive dissolved in the Al.sub.2 O.sub.3 grains so as to form solid solution therewith. The additive is contained in an amount of 0.01% to 12% by weight with respect to the Al.sub.2 O.sub.3 matrix and is at least one oxide of an element selected from the group consisting of Y, Mg, Cr, Ni, Co, and rare earth elements. The Al.sub.2 O.sub.3 grains have an average grain size no larger than 1.0 .mu.m while the hard phase constituent has an average grain size no larger than 0.6 .mu.m.

Abstract: A method for producing a ceramic is disclosed. The method involves comminuting a batch composed of from 6 to 95 percent of particulate ZrO.sub.2 and from 5 to 94 percent of particulate Al.sub.2 O.sub.3. A part of the particulate ZrO.sub.2 is in a metastable tetragonal crystal structure, for example, as a consequence of 3.sup.m/o of Y.sub.2 O.sub.3 dissolved therein and a part has a monoclinic crystal structure. The comminuted batch is compacted into a shape, and the shape is fired. The degree of comminution of the batch, the firing conditions and the proportions of stabilized and monoclinic ZrO.sub.2 in the batch are controlled to produce a dense, gas impervious ceramic which contains both metastable tatragonal and monoclinic ZrO.sub.2, and in such proportions that the ceramic has improved strength by comparison with an otherwise identical ceramic wherein all of the ZrO.sub.2 is in either a metastable tetragonal or a monoclinic crystal structure.

Abstract: A high-toughness ZrO.sub.2 sintered body having a stress-induced transformation ratio of 25% or more, which consists essentially of 40-90 volume % of ZrO.sub.2 containing 0.1-3 mol % of Nd.sub.2 O.sub.3 and 0.5-3.5 mol % of Y.sub.2 O.sub.3 as stabilizers of the crystal structure of ZrO.sub.2, and 10-60 volume % of at least one of Al.sub.2 O.sub.3, SiC, TiC, B.sub.4 C and TiB.sub.2.

Abstract: Hard crystalline sintered ceramic products, and a method for making them at substantially reduced sintering temperatures, are disclosed, the products being manufactured by the sintering of mixtures comprising one or more ceramic powders selected from among zirconia, stabilized zirconia, partially stabilized zirconia, alumina, mullite, cordierite, and MgAl.sub.2 O.sub.4 spinal together with a combination sintering aide including TiO.sub.2 and at least one transition metal oxide selected from the group consisting of copper oxide, manganese oxide, cobalt oxide and zinc oxide, the mixture comprising at least about 3.5 mole percent TiO.sub.2, at least about 1.3 percent of transition metal oxides, about 4.8-50 mole percent total of TiO.sub.2 +transition metal oxides, and the remainder ceramic powder. Sintering of these mixtures at temperatures typically 200.degree.-350.degree. C.

Abstract: Ceramic abrasive grits are formed by an impregnation process that involves preparing an alumina hydrate sol, drying the sol to form a porous solid, crushing the solid to produce particles, calcining the dried particles, preparing a mixture of an additive metal oxide or its precursor in a liquid vehicle, impregnating the mixture into the calcined particles, drying the impregnated particles, calcining the dried impregnated particles, and firing the particles to produce ceramic abrasive grits. The concentration of the modifying additive metal is greater at or near the surface of the grit than at the interior of the grit.

Abstract: The instant invention is directed to the production of ceramic bodies of at least one disperse inorganic component embedded in a phase of aluminum oxide by producing a mixture of aluminum powder and optionally an alloying element, and a disperse inorganic component which contains at least 40 vol. % of aluminum oxide, attriting the mixture, forming a body, and sintering the body in an oxidizing atmosphere.

Abstract: A refractory coating composition, adapted to be applied to a substrate by spraying or gunning, comprising:from about 25 to about 40% by weight alumina;from about 15 to about 25% by weight ceramic fiber;from about 40 to about 60% by weight colloidal silica; andsufficient water to form an aqueous suspension thereof.

Abstract: A ceramic article is disclosed. The article is composed of from 6 to 50 percent of particulate ZrO.sub.2 having an ultimate particle size less than 2 .mu.m, from 50 to 94 percent of particulate Al.sub.2 O.sub.3, from 1/4 to 3 percent of MnO.sub.2 and from 1/4 to 3 percent of TiO.sub.2.

Abstract: A ceramic cutting insert for high speed machining of materials is provided having an integral chip control surface thereon.

Abstract: A beta alumina sintered body having no tantalum component in an intergranular phase is manufactured by mixing raw materials consisting essentially of 8.0-10.0 wt % of sodium oxide, 3.0-5.5 wt % of magnesium oxide and/or 0.1-2.0 wt % of lithium oxide, 0.01-0.5 wt % of tantalum oxide, and the remainder of aluminum oxide to obtain raw material powders; forming the raw material powders to obtain a formed body; and sintering the formed body.

Abstract: A hot-pressed ceramic composite of mullite/yttria stabilized zirconia/boron nitride having good resistance to thermal shock and good erosion/corrosion resistance to molten alloys, and a method for producing said composite which comprises the blending of fused mullite with boron nitride.

Abstract: An aqueous plastic composition of an inorganic powder which per se has substantially no plasticity which comprises: the inorganic powder and a polysaccharide of natural origin.The molding and sintering of the plastic composition provide a sintered body of high mechanical strength and dimensional accuracy.

Abstract: The mechanical strength of stabilized zirconia is improved without lowering the ion conductivity by providing a solid electrolyte comprising stabilized zirconia and a metal oxide dispersed within grains or grain boundaries of stabilized zirconia, the metal oxide having an average submicron particle size and stabilized zirconia having an average particle size larger than 1 micron, typically larger than 10 .mu.m or even 100 .mu.m.

Abstract: A hot-pressed ceramic composite of mullite/yttria stabilized zirconia/boron nitride having good resistance to thermal shock and good erosion/corrosion resistance to molten alloys, and a method for producing said composite which comprises the blending of fused mullite with boron nitride.

Abstract: A sinterable powder of zirconium dioxide and additives from the group of oxides consisting of titanium, tantalum, as well as optionally magnesium, aluminum, scandium, yttrium and rare earths, incorporated in the crystal lattice of the zirconium dioxide. The sinterable powder is obtained by coprecipitation of zirconium hydroxide and the hydroxides and/or hydrated oxides of the additives from an essentially aqueous solution, with drying and calcining. Hydrolysis-sensitive starting materials, such as, TiCl.sub.4, are used in the form of their reaction products with multivalent alcohols, such as, ethylene glycol.

Abstract: Ceramic bodies are bonded together via a layer of an oxidation reaction product of a molten metal, which metal is present in one or both of the ceramic bodies prior to bonding. At least one of the ceramic bodies comprises a ceramic product formed by the oxidation reaction of molten parent metal (e.g., alumina from molten aluminum) and grown as molten metal is transported through, and oxidized on the surface of, its own oxidation product. One or both of the ceramic bodies used in the bonding process contains surface-accessible channels of residual metal, i.e., metal channels which have resulted from molten-metal transport during the ceramic growth process. When the suitably assembled ceramic bodies are heated in the presence of an oxidant at a temperature above the melting point of the residual metal, molten metal at the surface of at least one of the body ceramic bodies reacts with the oxidant to form a layer of oxidation reaction product, which may or may not incorporate at least one filler material.

Abstract: A process for producing a high density ceramic of perovskite represented by the formula:ABO.sub.

Abstract: Thin inorganic sintered structures having strength and flexibility sufficient to permit bending without breakage in at least one direction to a radius of curvature of less than 20 centimeters, methods for making them, and products incorporating them, are described. Preferred sintered ceramic structures according to the invention can comprise zirconias, titanias, aluminas, silicas, rare earth metal oxides, alkaline oxides, alkaline earth metal oxides and first, second, and third transition series metal oxides and combinations thereof and therebetween. Sintered metal structures can also be provided.

Abstract: Zirconium-doped pseudoboehmite with the following properties: zirconium content of 0.5 to 10 mol % relative to Al water content of 20 to 35 weight percent total of the anionic impurities less than 0.5 weight percent. It is synthesized by a process wherein zirconium salt is added in calculated quantity to an aqueous aluminum sulfate solution, the resulting mixture is fed simultaneously with a sodium aluminate liquor into a water pool having a temperature of 50.degree. to 100.degree. C., thereby precipitating zirconium-doped alumina gel while a pH of 3.5 to 8 is maintained, the pH of the suspension is adjusted after addition of the aluminum sulfate solution to 8.5 to 10.5 by further addition of sodium aluminate liquor, the suspension is digested if necessary at the pH of 8.5 to 10.5 and the temperature of 50.degree. to 100.degree. C. for a period of up to 24 hours, the formed pseudoboehmite crystals are filtered off, the filter cake is redispersed with water and the suspension is sprayed-dried.

Abstract: A ceramic element of a zirconia oxygen sensor is shaped from a powder mixture. The mixture, comprising a ceramic powder having an average particle size less than or equal to 1 micrometer, a gel-forming material and a gel forming material solvent, is molded at a temperature and pressure sufficient to produce the ceramic element having a density of at least 5.5 g/cm.sup.3.

Abstract: A high zirconia fused cast refractory having excellent thermal cycle resistance which comprises, as chemical components of the refractory, from 90 to 95% by weight of ZrO.sub.2, from 3.5 to 7% by weight of SiO.sub.2 and from 1 to 3% by weight of Al.sub.2 O.sub.3 and which does not substantially contain any one of P.sub.2 O.sub.5, B.sub.2 O.sub.3 and CuO.

Abstract: Disclosed is a high-strength alumina sintered body which consists of 1 to 30% by weight, based on Al.sub.2 O.sub.3 and ZrO.sub.2, of ZrO.sub.2 and 99 to 70% by weight, based on Al.sub.2 O.sub.3 and ZrO.sub.2, of Al.sub.2 O.sub.3, and unavoidable impurities, said sintered body having a peak based on ZrO.sub.2 at a position of a wave body having a peak based on ZrO.sub.2 at a position of a wave number of 600.+-.10 cm.sup.-1 in a measurement chart of the laser Raman spectrum analysis. This sintered body has a high flexural strength and a high breaking toughness in combination.

Abstract: A composition suitable for use in the manufacture of a ceramic material comprises free-flowing substantially non-aggregated particulate zirconia. A substantial proportion of the zirconia is present in the tetragonal crystalline form and the particles of zirconia contain alumina in an amount of from 1 to 10% by weight expressed as Al on ZrO.sub.2. The particles are substantially free of silica.The particles of zirconia can be coated with an oxide or hydrous oxide of a stabilizing agent for zirconia such as an oxide or hydrous oxide of yttrium, calcium, magnesium, barium, strontium or cerium.An oxidation process is described for the manufacture of the tetragonal crystalline zirconia by the oxidation of zirconium halide in the presence of aluminium halide at high temperature in the vapor phase.

Abstract: The invention relates to a refractory thixotropic self-hardening vibration compound on the basis of zirconium silicate having the following chemical composition (in % by mass);______________________________________ 20 to 30% SiO.sub.2 20 to 45% Al.sub.2 O.sub.3 0.7 to 1.4% TiO.sub.2 0.2 to 0.8% P.sub.2 O.sub.5 0 to 1.5% K.sub.2 O + Na.sub.2 O + LiO.sub.2 0 to 1.0% Fe.sub.2 O.sub.3 0 to 0.05% CaO residue ZrO.sub.

Abstract: Improved alumina-zirconia composite sintered materials with sufficient high mechanical strength and thermal shock resistance as well as excellent hardwearing resistance are made by mixing, heating and melting zirconia and alumina, then the produced melt was quenched, and the resulting solid was ground and milled while adding thereto at least one compound of ceria and/or titania, to an average grain size of from about 0.5 to about 1.5 .mu.m, and subjected the resulting powder to molding and sintering at a temperature of from 1450.degree. to about 1600.degree. C., said zirconia, ceria and titania being employed in the amount of about 10-20%, about 3-7%, and about 15-25% by weight, respectively, plus the balance of alumina. Said sintered materials are useful for employment in structural materials, refractorial materials, erosion resistance materials, cutting tool materials, grinding and polishing materials, etc.

Abstract: A ceramic consisting essentially of from 1 to 15 percent of glass and 99 to 85 percent of a mixture of particulate Al.sub.2 O.sub.3 and particulate ZrO.sub.2 is disclosed. ZrO.sub.2 is present in a sufficient amount, usually from 1/4 to 6 percent based on the weight of the ZrO.sub.2 and Al.sub.2 O.sub.3, to strengthen the ceramic significantly, by comparison with an otherwise identical ceramic where the particulate ZrO.sub.2 is replaced either by the glass or by particulate Al.sub.2 O.sub.3. The glass constitutes a vitreous phase bonding the particulates into a dense, gas impervious structure, and can be a calcium magnesium silicate glass containing from 45 to 80 percent of SiO.sub.2, from 8 to 55 percent of CaO and MgO, and not more than 15 percent of Al.sub.2 O.sub.3.