Abstract: An alumina-zirconia electrofusing material whose chemical composition consists of about 30-75 wt. % Al.sub.2 O.sub.3 and about 25-70 wt. % ZrO.sub.2 is provided in an amount of about 5-50 wt %, and this electrofusing material is mixed with other materials, and a resultant mixture is press-shaped and fired to produce a slide gate refractory. In order to further improve resistance to corrosion and spalling, particle diameters of the electrofusing material are continuously distributed in a range from about 0.1 mm to about 2.5 mm.

Abstract: A method of producing a self-supporting ceramic composite body having therein at least one cavity which inversely replicates the geometry of a positive mold of parent metal. The method includes embedding the mold of parent metal within a conformable bed of filler to provide therein a cavity shaped and filled by the mold. The assembly is heated to melt the parent metal mold, e.g., an aluminum parent metal mold, and contacted with an oxidant to oxidize the molten parent metal to form a polycrystalline material which grows through the surrounding bed of filler, the molten metal being drawn through the growing polycrystalline material to be oxidized at the interface between the oxidant and previously formed oxidation reaction product whereby the cavity formerly filled by the mold of parent metal is eventually evacuated of the metal. There remains behind a cavity whose shape inversely replicates the original shape of the mold.

Abstract: Two composition areas of partially stabilized ZrO.sub.2 /HfO.sub.2 alloys have been discovered which exhibit pseudo-plasticity through the presence of transformation bands and with the substantial absence of microcracking. The first area consists essentially, in mole percent, of 0.5-8% of at least one toughening agent in the indicated proportion selected from the group consisting of 0-8% YNbO.sub.4, 0-8% YTaO.sub.4, 0-8% RENbO.sub.4, 0-8% RETaO.sub.4, 0-8% YVO.sub.4, 0-8% REVO.sub.4, 0-8% MgWO.sub.4, 0-8% MgMoO.sub.4, 0-8% CaWO.sub.4, 0-8& CaMoO.sub.4, and 0-8% SnO.sub.2, and 0.5-10% of at least one stabilizer oxide in the indicates proportion selected from the group consisting of 0-3.5% Y.sub.2 O.sub.3, 0-3.5% Sc.sub.2 O.sub.3, 0-3.5% RE.sub.2 O.sub.3, 0-10% CeO.sub.2, 0-10% TiO.sub.2, 0-10% SnO.sub.2, 0-10% CaO, and 0-10% MgO, with the remainder ZrO.sub.2 /HfO.sub.2 alloy. The second area consists essentially, in mole percent, of 8-16% CeO.sub.2 and 0.25-5% Nb.sub.2 O.sub.5 and/or Ta.sub.2 O.sub.

Abstract: A ceramic material suitable for packaging of large scale integrated circuits is produced by the process of forming a mixture of a powdered glass ceramic material which is a glassy precursor to cordierite ceramic material, formed by the steps which are as follows:a. Mix tetragonal phase material selected from the group consisitng of zirconia or hafnia powder containing a stabilizing oxide compound selected from the group consisting of MgO, CaO and Y.sub.2 O.sub.3 and a glass frit powder or frit of a glassy precursor of cordierite glass ceramic to yield a suspension of solids. Preferably, a binder is included.b. Disperse the suspended solids to yield a dispersion of the zirconia or hafnia with the stabilizing oxide compound and the glassy precursor.c. Densify the dispersion of zirconia or hafnia with the stabilizing oxide compound and the glassy precursor by a sintering heat treatment at a temperature of about 840.degree. C.

Abstract: Ceramic bodies suitable for use in the filtration of molten metal are formed by immersing a porous organic substrate material in an aqueous thixotropic slurry containing yttria, zirconia and alumina; expelling excess slurry; drying the impregnated material; and heating to an elevated temperature to burn off the organic material and sinter the ceramic materials. The resulting zirconia-alumina ceramic bodies have from about 5-80% of the zirconia in a monoclinic phase and the remainder of the zirconia essentially in a stabilized cubic phase due to the yttria. The ceramic bodies thus produced have excellent strength, density, and thermal shock resistance properties.

Abstract: The ceramic sinter is composed of a metal oxide such as ZrO.sub.2 and 10-90 vol. % of metal fluoride which is selected from the group having not less than 2.5 electronegativity difference between fluoride and the metal element.The ceramic sinter has a thermal expansion coefficient of 15-20.times.10.sup.-6 /.degree.C. and is suitable for bonding with general use metals such as stainless steel to form a composite body of the ceramic sinter and the metal without causing a substantial thermal stress at the juncture thereof.

Abstract: A monolithic ceramic structure, useful as a support for catalytic material or as a fluid filter, has a high surface area phase which consists essentially of a porous metal oxide material, at least 50% by weight of which is alumina, titania, and/or zirconia, and phosphate dispersed substantially througout the porous metal oxide material. The presence of the phosphate stabilizes the porous metal oxide material against thermal degradation during sintering or exposure to elevated temperatures encountered in catalytic service and thereby aids in the retention of higher overall surface area in the monolithic structure.

Abstract: Zirconia toughened alumina (ZTA) is produced from precursor salts. The precursor salts are coprecipitated from solution to yield a gel in a liquid phase. The gel in excess of the critical temperature and pressure is dried at a temperature and pressure in excess of the critical temperature and pressure of the liquid phase to thereby convert the liquid phase to a gas. The solid particles, when separated from the gas, form a fine particulate ZTA which, upon consolidation yields near theoretical density toughened ceramics.

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: Fused cast refractory moldings having a random microstructure, which are near in size and configuration to the desired final shape, and process and apparatus used in their manufacture are described. The process includes rapid melting of the refractory material followed by controlled rapid cooling. Laminated composite fused cast refractories may be produced.

Abstract: The invention relates to refractory materials.It relates to a refractory product without cracks obtained by fusion under oxidizing conditions and cast from a mixture of starting materials such that the product obtained has the average chemical composition by weight, in % by weight based on the following oxides:______________________________________ ZrO.sub.2 >92 SiO.sub.2 2-6.5 Na.sub.2 O 0.12-1.0 Al.sub.2 O.sub.3 0.4-1.15 Fe.sub.2 O.sub.3 + TiO.sub.2 <0.55 P.sub.2 O.sub.5 <0.05. ______________________________________Use in the glassmaking sector.

Abstract: A ceramic material which comprises a composite of zirconia and O'-/.beta.'-sialon wherein the volume ratio of O'-sialon to .beta.'-sialon is in the range of from 1:7 to 7:1, preferably from 1:3 to 3:1.

Abstract: A SiC whisker-reinforced ceramic article produced by subjecting the SiC whiskers to acid- and/or base-washing; subjecting ceramic particles and SiC whiskers to fluid classification; forming a suspension of the powdered ceramic and SiC whiskers; consolidating the suspension to form a green compact; optionally infiltrating the green compact with an aluminum compound which is a precursor to Al.sub.2 O.sub.3, and pressureless sintering the green compact to produce an SiC whisker-reinforced composite having high relative density at high SiC whisker loading.

Abstract: This invention is directed to the production of ceramic alloys consisting essentially of partially stabilized ZrO.sub.2 and/or ZrO.sub.2 -HfO.sub.2 solid solution and/or HfO.sub.2 exhibiting high toughness through the inclusion of about 0.5-8 mole %, as expressed on the oxide basis, of YNbO.sub.4 and/or YTaO.sub.4 and/or MNbO.sub.4 and/or MTaO.sub.4, wherein M represents Mg.sup.+2, Ca.sup.+2, Sc.sup.+3 and/or a rare earth metal ion selected from the group of La.sup.+3, Ce.sup.+4, Ce.sup.+3, Pr.sup.+3, Nd.sup.+3, Sm.sup.+3, Eu.sup.+3, Gd.sup.+3, Tb.sup.+3, Dy.sup.+3, Ho.sup.+3, Er.sup.+3, Tm.sup.+3, Yb.sup.+3, and Lu.sup.+3 substituted for Y, and the use of at least 5 volume percent of such ceramic alloys to toughen hard refractory ceramics.

Abstract: A ceramic article having good fractured toughness comprising substantially spherical ceramic particles, which may be a ceramic oxide such as zirconia or zirconia combined with yttrium oxide. The ceramic particles are compacted and sintered to a density greater than 90 percent of theoretical density. The article is characterized by a substantially uniform chemical composition and a substantially inclusion-free, homogeneous microstructure, which may be a metastable crystalline phase with less than 10 volume percent monoclinic crystalline phase. The article is produced by dissolving, such as in water, a soluble compound containing a metal, e.g. zirconium, to form a solute. A precipitation agent, such as sodium hydroxide or ammonium hydroxide, is combined with the solute to precipitate a hydrophilic colloid of the metal hydroxide, such as zirconium hydroxide. The precipitate is formed into particles which are rapidly solidified while preventing agglomeration thereof.

Abstract: Mixed oxides of alumina and zirconia having a controlled granulometric distribution, consisting essentially of spherical, submicronic particles, wherein zirconia is distributed uniformly in alumina and may reach 38% by weight, said zirconia being in the stabilized form at room temperature in the tetragonal phase, after having subjected the amorphous hydrated composite oxides to thermal treatments, wherein occurs the transition of zirconia to the tetragonal phase.

Abstract: A ceramic comprising a matrix of Al.sub.2 O.sub.3, ZrO.sub.2 (partially or fully stabilized) or mixtures of Al.sub.2 O.sub.3 and ZrO.sub.2 with strontium aluminate plate-shaped grains distributed throughout the matrix results in a ceramic with high toughness, high strength and good hardness. SrO/Al.sub.2 O.sub.3 molar ratios between 0.02 and 0.20 result in in-situ formation of plate-shaped grains approximately 0.5 .mu.m in thickness and 5.0 .mu.m in breadth in tetragonal zirconia polycrystalline ceramic matrices. The in-situ formation of strontium aluminates allows high volume loading of platelets to occur and high toughness is achieved without the loss of strength. High alumina compositions have the added benefit of higher strength, lower thermal expansion, higher modulus and higher thermal conductivity than zirconia ceramics with comparable toughness.

Abstract: A particulate composition suitable for use in a process of dressing a refractory structure which includes the steps of projecting against a site of refractory structure to be dressed a comburent gas stream carrying a mixture comprised of fuel particles and refractory oxide particles, which fuel particles are comprised of at least one element which is oxidisable to form at least one refractory oxide; and causing or allowing the fuel particles to burn, the particulate composition being a mixture including fuel particles comprised of at least one element which is oxidisable to form a refractory oxide; refractory oxide particles; and particles of fluxing agent the fluxing action of which is such that when the mixture is projected in a comburent gas stream and the fuel particles are caused or allowed to burn, the refractory structure becomes softened to an extent such that the refractory structure becomes dressed by removal or displacement of material thereof under the mechanical action of the impinging comburent

Abstract: A high-temperature protective coating comprising a ceramic material, in particular for structural components of super-alloys, characterized in that at least one oxide of a metal of subcolumn 4 of the periodic table of elements is stabilized with at least one further oxide of a metal and is enveloped in a corrosion-resistant manner, at least in some regions, by at least one ceramic material.

Abstract: Fused AZS grain refractory compositions suitable for making ceramically or chemically bonded refractory articles, and the articles so made, are disclosed. The refractory compositions consist essentially of (a) 40-85 wt. % fused AZS grain, and (b) 15-50 wt. % of at least one constituent selected from the group consisting of (i) 10-20 wt. % reactive alumina and (ii) 0-45 wt. % chromic oxide.

Abstract: The invention relates to a composite body comprising a first part of ceramic material, a second part of metallic material, of ceramic material or of a mixture of metallic and ceramic material, and a third part of a melting ceramic which seals together the first and second parts, and comprises a frit of Al.sub.2 O.sub.3 and either one or more alkaline earth metal oxides or one or more rare earth metal oxides or a combination of these two oxides. According to the invention, the melting ceramic contains a filler material which occupies at least 20% and at most 50% of the volume of the melting ceramic.

Abstract: The present invention is in a sintered molding of partially stabilized zirconium oxide having a microstructure of 40 to 70 volume percent cubic phase, 30 to 70 volume percent tetragonal phase, and up to 10 volume percent monoclinic phase wherein the tetragonal phase is present in the form of precipitates less than 200 nm. A mixture of magnesia and yttria is used to stabilize the zirconia. Optionally, the sintered molding may further contain up to 20 wt. % spinel.

Abstract: An extruded and sintered Al.sub.2 O.sub.3 body having high flexural strength is produced by extruding and sintering and extrusion mixture of alpha-Al.sub.2 O.sub.3 powder, an organic dispersing agent, an optional deaeration agent, and a zirconia sol. The zirconia sol is present in a small amount such that upon firing the final ZrO.sub.2 content of the final body is less than 1 weight percent. The sintered alumina body has a uniform distribution of ZrO.sub.2 particles in the size range of 0.1-1.0 microns.

Abstract: A composite structure useful as an implant material in bones includes a matrix made of Al.sub.2 O.sub.3 --ZrO.sub.2 (Y.sub.2 O.sub.3) ceramic material. The surface of the matrix is non-monocrystallized. A bio-active layer covers the matrix surface.

Abstract: A refractory composition is disclosed which possesses low porosity, high density, exceptional strength and high abrasion resistance and is useful for lining fluid catalytic converter units, e.g., catalyst transfer lines, riser lines, J-bends, cyclones and all other areas where hot abrasion resistance and low thermal conductivity are desired. The composition consists essentially of by weight: (a) 44 to 89% of an abrasion-resistant refractory grain; (b) 10 to 50% of a hydraulically setting cement; (c) 1 to 6% of a filler consisting of very fine, substantially spherical particles of a metal oxide selected from the group consisting of Al.sub.2 O.sub.3, Cr.sub.2 O.sub.3, ZrO.sub.2, TiO.sub.2, clay minerals, carbon and fume SiO.sub.2 ; and (d) 0.01 to 1%, based on the total weight of the constituents (a), (b) and (c), of additives selected from deflocculants and wetting agents.

Abstract: Solid, transparent, non-vitreous, microspheres (zirconia-silica) are formed by extractive gelation (extracting carboxylic acid away from zirconyl carboxylate) of a sol in liquid medium such as hot peanut oil. Zirconyl carboxylate precursor sol is prepared and added in droplet form to the liquid extractant (peanut oil) at an elevated temperature at which a carboxylic acid is liberated from the zirconyl carboxylate. The droplets remain in the extractant for sufficient time to form stable gel spheroids which are separated from the extractant and fired to convert them to durable spheroids useful as lens elements in retroreflective sheeting.

Abstract: In processes of forming a refractory mass on a surface, a mixture of refractory particles and oxidizable particles which react exothermically with oxygen to generate sufficient heat to soften or melt at least the surfaces of the refractory particles are sprayed against that surface to bring about formation of said refractory mass. To promote the reliable and consistent formation of a durable refractory mass, the granulometry of the particles which are sprayed in the mixture is such that the 80% and 20% grain sizes of the refractory particles (that is, the screen mesh sizes G.sub.80 and G.sub.20 through which respectively 80% and 20% by weight of the particles will pass) have a mean greater than the mean of the 80% and 20% grain sizes of the oxidizable particles and the size range spread factor f(G) of the refractory particles is at least 1.

Abstract: Silicon carbide whisker-reinforced ceramic composites are fabricated in a highly reproducible manner by beneficating the surfaces of the silicon carbide whiskers prior to their usage in the ceramic composites. The silicon carbide whiskers which contain considerable concentrations of surface oxides and other impurities which interact with the ceramic composite material to form a chemical bond are significantly reduced so that only a relatively weak chemical bond is formed between the whisker and the ceramic material. Thus, when the whiskers interact with a crack propagating into the composite the crack is diverted or deflected along the whisker-matrix interface due to the weak chemical bonding so as to deter the crack propagation through the composite. The depletion of the oxygen-containing compounds and other impurities on the whisker surfaces and near surface region is effected by heat treating the whiskers in a suitable oxygen sparaging atmosphere at elevated temperatures.

Abstract: A refractory liner composition which consists essentially of carbon and a composite selected from the group consisting of zirconia and O'-sialon and zirconia and silicon oxynitride.

Abstract: The invention relates to ceramic articles.It relates to an article made of ceramic material produced by fusing and casting in a mold a composition based on alumina, zirconia, silica and an alkali metal oxide, said article consisting of crystalline corundum and zirconia phases and of a vitreous phase, said zirconia being substantially in monoclinic form from the core to the skin of said article, and having, in at least one of its parts, a thickness lower than or equal to 30 mm and being intended for an application where mechanical strength and/or abrasion resistance are of primary importance, said composition consisting essentially, in % by weight based on the oxides, of:______________________________________ Al.sub.2 O.sub.3 40-75 ZrO.sub.2 20-55 SiO.sub.2 5-20 Na.sub.2 O 0-2.7 K.sub.2 O 0.15-4.25 Fe.sub.2 O.sub.3 + TiO.sub.2 + CaO + MgO 0-2, ______________________________________with the condition that the weight ratio ##EQU1## is between 0.07 and 0.14 inclusive.

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

Abstract: A process for the production of a raw material used for the production of a zirconia sintered body is disclosed. A power containing principally zirconium compounds and a stabilizing agent is added to a solution or slurry containing at least one metal element selected from the group consisting of Mn, Fe, Co, Ni, Cu, and Zn. The stabilizing agent is Y.sub.2 O.sub.3, CaO, MgO, CeO.sub.2, a yttrium compound, calcium compound, magnesium compound or cerium compound which can produce Y.sub.2 O.sub.3, CaO, MgO, or CeO.sub.2 by thermal decomposition. The selected metal element from the group will act as a coating on the zirconia sintered body.

Abstract: The present invention provides a fine-grained ceramic formed body of 0.5 to mole % rare earth oxide and 0.5 to 7 mole % MgO-containing ZrO.sub.2, wherein the cubic granules thereof are coated with Mg-Al spinel particles.The present invention also provides a process for the production of such formed bodies, wherein a ZrO.sub.2 powder alloyed with rare earth oxide, which contains small amounts of Al.sub.2 O.sub.3, is pressed and sintered in the presence of MgO at a temperature of from 1400.degree. to 1600.degree. C. and optionally subsequently tempered at a temperature of from 1200.degree. to 1350.degree. C.

Abstract: A composite ceramic material having improved properties is disclosed as well as several methods for preparing the same. The composite powder is substantially comprised of zirconia and spinel phases, produced by precipitation and calcination of the precipitate of the oxide forming precursor salts. A preferred method for introducing the zirconium is as a soluble and/or decomposable salt during precipitation of the spinel forming hydroxyl or halo hydroxyl spinel forming salts. The zirconium salt decomposes to zirconia during calcining and/or sintering of the powder resulting from the precipitation. A preferred composite is that obtained from magnesium and aluminum salts, resulting in a MgAl.sub.2 O.sub.4 spinel and intimately admixed ZrO.sub.2 which contains a stabilizing agent.

Abstract: A sliding member formed of sintered silicon nitride shows improvement in strength and abrasion resistance when substantially all the .beta.-phase type fine silicon nitride particles present as a main component in the sintered silicon nitride have major diameters not exceeding 60 .mu.m and aspect ratios of not less than 5 and the aforementioned fine silicon nitride particles have a relative density of not less than 98%.

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 base on the 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.

Abstract: A fused metal oxide ceramic coating is disclosed for application in a particular region of the target employed in an x-ray tube. The disclosed ceramic coating enhances the thermal emittance of a refractory metal target and comprises the fused product of a metal oxide physical mixture comprising Al.sub.2 O.sub.3, ZrO.sub.2, and TiO.sub.2 which exhibits a minimum melting point of approximately 1580.degree. C. A preferred ceramic coating comprises from about 40 weight percent up to about 70 weight percent TiO.sub.2, from about 20 weight percent up to about 40 weight percent ZrO.sub.2, and from about 10 weight percent up to about 20 weight percent Al.sub.2 O.sub.3. A process for the in situ preparation of said ceramic coating is also disclosed along with a particular rotating type x-ray tube and radiographic imaging system employing said improved target.

Abstract: A ceramic material which comprises a composite of zirconia and O'-sialon or silicon oxynitride.The ceramic material may comprise a dispersion of zirconia in an O'-sialon matrix and such a dispersion is obtained when the amount of zirconia is from 5 to 30 volume percent, preferably 15 to 25 volume percent, based on the total volume of the composition.

Abstract: An oxygen sensing element having an oxygen-ion conductive solid electrolyte body, a measuring and a reference electrode formed on the solid electrolyte body so as to communicate with a measurement and a reference gas, respectively. The solid electrolyte body is formed by firing an unfired body of an oxygen-ion conductive solid electrolyte material containing a sitnering aid. The firing temperature is selected within a range defined by a permissible lowest sintering point of the unfired formed body, and an upper limit which is 60.degree. above the permissible lowest sintering point, whereby an amount of the sintering aid left on the surface of the first solid electrolyte body is smaller than that left within an interior structure of the solid electrolyte body, as viewed in a transverse cross sectional plane of the solid electrolyte body.

Abstract: Ceramic moldings containing finely crystalline cordierite are described, which are obtainable by the intensive grinding of precrystallized cordierite powder, mixing the powder with second additive phases of higher modulus of elasticity, shaping the mixture, and sintering the greenware thus obtained in a siliceous atmosphere at temperatures between 900.degree. and 1400.degree. C. The moldings according to the invention have not only good mechanical strengths but also outstanding dielectric and thermal properties; they are therefore especially suitable for use as dielectrics and as thermal insulating components.

Abstract: A ceramic body has a surface region that contains tetragonal zirconia. The body is partially stabilized with yttria and, optionally, ceria. Substantially the entire surface region is composed of recrystallized tetragonal strain free grains of yttrium oxide zirconium oxide. The content of yttrium in the surface region is substantially the same as the average content of yttrium in the ceramic body, and the surface region is covered with a thin layer of stable tetragonal grains.

Abstract: The stabilization of zirconia when used as a ceramic by various stabilizers has been known but a new and improved stabilized particulate zirconia has now been developed showing the important advantages.The particulate zirconia now developed is coated with a hydrous oxide of titanium and/or of aluminium and with at least one hydrous oxide of yttrium, calcium, magnesium, strontium or cerium.

Abstract: Alumina-zirconia composite sintered materials having sufficient high-temperature strength and thermal shock resistance as well as excellent mechanical strength are made by mixing Bayer alumina and/or bauxite as an alumina and baddeleyite and/or zircon sand as a zirconia material in amounts of 50 to 95% by weight of alumina, the balance being zirconia, respectively, subjecting the mixture to heating, melting and quenching, grinding the resulting solid to an average grain size of 10 .mu.m or smaller, and subjecting the resulting powder to molding and sintering.

Abstract: A high strength zirconia ceramic composition consisting essentially of a compound of ZrO.sub.2 containing less than 5.0 mol % Y.sub.2 O.sub.3 as a stabilizer and further containing 1-30 wt % aluminum and magnesium contents to the amount of the compound of ZrO.sub.2 in terms of Al.sub.2 O.sub.3 and MgO. In the case that the compound of ZrO.sub.2 further contains CeO.sub.2 as a stabilizer, the total amount of Y.sub.2 O.sub.3 and CeO.sub.2 is determined to be 1.0-15 mol % to the amount of the compound of ZrO.sub.2.

Abstract: The invention consists of zirconia base with high hydrothermal stability which:(a) consists essentially of at least 40 weight % of partially stabilized zirconia of the ZrO.sub.2 -Y.sub.2 O.sub.3 -CeO.sub.2 system wherein the proportion of ZrO.sub.2, Y.sub.2 O.sub.3, and CeO.sub.2 is within the range defined by the line connecting points F, G, L, M, N and K in a ternary diagram (ZrO.sub.2, YO.sub.1.5, CeO.sub.2), the vertices of said points being given by the following molar % of ZrO.sub.2, YO.sub.1.5, and CeO.sub.2, respectively:F (88, 10, 2),G (89, 10, 1),L (93.5, 4, 2.5),M (93, 2, 5),N (88, 1, 11), andK (86, 1,13),and 3 to 60 weight % of at least one of Al.sub.2 O.sub.3, MgO.Al.sub.2 O.sub.3, spinel and mullite, and(b) has a mean crystal grain size not exceeding 2 micrometers and a bending strength of at least 100 kgf/mm.sup.2, said ZrO.sub.2 containing a minimum of 50 volume % tetragonal crystal structure and a maximum of 5 volume % monoclinic crystal structure when tested in steam of 180.degree. C.

Abstract: High density fine ceramic sintered bodies are disclosed, which have a maximum pore diameter of not more than 10 .mu.m and a porosity of not more than 0.5%. A process for producing such high density fine ceramic sintered bodies comprises the steps of mixing a ceramic raw material powder with a sintering aid, grinding the resulting mixture granulating and shaping the mixture, and firing the shaped body. The granulated powder is once forcedly dried, and upon necessity is added with water and/or sieved to obtain a uniform granulated powder having a given amount of water.

Abstract: A process is described for the preparation of a ceramic green body by hydrolyzing at least one alkoxide selected from each of two specified groups to form a dispersion of their reaction product, concentrating the dispersion to a sediment without drying it, and admixing a binder and a plasticizer with the sediment to make a ceramic slip formulation. A release agent can optionally be admixed. The slip formulation is then cast as a ceramic green body. The proportions of alkoxides can be adjusted, as desired, to produce a ceramic green body which is dielectric and useful for microcapacitors or as a conductor.

Abstract: A dielectric ceramic composition for temperature compensating monolithic ceramic capacitors consists essentially of a solid solution composed of barium oxide, strontium oxide, silicon oxide and zirconium oxide, which, when calculated in terms of BaO, SrO, SiO.sub.2 and ZrO.sub.2 respectively and expressed by the formula:x(BaO.sub.1-.alpha. SrO.sub..alpha.)--ySiO.sub.2 --zZrO.sub.2(wherein x, y, z are the weight percentages of the respective components, x+y+z=100, and 0.ltoreq..alpha..ltoreq.0.9), have compositional proportions falling within the polygonal area defined by the points A, B, C and D in FIG. 1, the sets of x, y and z at said points A, B, C and D being as follows:______________________________________ x y z ______________________________________ A 50 49 1 B 50 20 30 C 15 20 65 D 15 84 1 ______________________________________The composition may contain, as an additive, aluminum oxide in an amount of not more than 20 parts by weight in terms of Al.sub.2 O.sub.

Abstract: A magnetic head slider and a material for it which comprises a sintered body obtained by sintering a raw material powder composed of 65 to 90% by weight of ZrO.sub.2 component containing therein a stabilizer and the balance of Al.sub.2 O.sub.3 component, 2% by weight or below of which has been substituted with a binder. The stabilizer is Y.sub.2 O.sub.3, MgO or CeO and the binder is Y.sub.2 O.sub.3 or MgO.

Abstract: Disclosed herein is a method of manufacturing dense cordierite, which includes steps of molding a powder mainly consisting of cordierite crystals and having an average particle size of not more than 5 .mu.m, firing a resulting molding at a temperature of from 1,350.degree. to 1,430.degree. C., whereby the sintered body having a porosity of not more than 6% and a bulk specific gravity of not less than 2.4 is obtained.