Abstract: Fused abrasive particles comprising eutectic material comprising Al2O3—MgO-REO eutectic. The fused abrasive particles can be incorporated into abrasive products such as coated abrasives, bonded abrasives, non-woven abrasives, and abrasive brushes.

Abstract: A dielectric ceramic composition including at least a first component containing Al2O3, MgO and ROa (R is at least one element selected from the group consisting of La, Ce, Pr, Nd, Sm, Eu, Tb and Gd; a is a value stoichiometrically determined in accordance with the valence of R); SiO2 as a second component; and a third component containing a glass composition including two or more components containing at least one selected from the group consisting of SiO2 and B2O3. A dielectric ceramic composition stably has a high strength in a high frequency band such as microwave, millimeter wave, etc., and has a small dielectric constant, a low loss, and a small temperature constant at capacitance.

Abstract: In order to improve a heat-cycling-durability of a structural body in which a nitrided material is provided on a substrate containing at least metallic aluminum, a heat-resistant structural body having a substrate containing at least metallic aluminum and a nitrided material formed on the substrate provided. The nitrided material is composed mainly of an aluminum nitride phase and a metallic aluminum phase. Preferably, the nitrided material contains at least one metallic element selected from Group 2A, Group 3A, Group 4A, and Group 4B in Periodic Table.

Abstract: The invention relates to free-flowing refractory castable material and castings produced therefrom. Refractory nonbasic and basic refractory castable materials have been known for a long time. The traditional refractory castable materials have thixotropic properties and must be lined sing vibration technology. In the past, free-flowing refractory castable materials were solely based on alumina raw materials. Attempts to produce an aqueous, highly concentrated basic suspension which would Coma the basis of free-flowing refractory castable materials failed to meet the requirements in terms of theological properties and a low degree of to hydration of the MgO-based materials. It is the aim of the invention to provide the above-mentioned refractory castable material for the monolithic lining or repair of high-temperature equipment and for the production of refractory castings. This is achieved by providing a fine-grained and a mixed fine and coarse-grained alternative.

Abstract: A ceramic comprising predominately a cordierite-type phase approximating the stoichiometry Mg2Al4Si5O18 and having a coefficient of thermal expansion (25-800° C.) of greater than 4×10−7/° C. and less than 13×10−7/° C. and a permeability and a pore size distribution which satisfy the relation 2.108 (permeability)+18.511 (total pore volume)+0.1863 (percentage of total pore volume comprised of pores between 4 and 40 micrometers)>24.6. The ceramic is suitable in the fabrication of cellular, wall-flow, diesel particulate filters having a pressure drop in kPa that at an artificial carbon soot loading of 5 grams/liter and a flow rate of 26 scfm is less than 8.9−0.035 (number of cells per square inch)+300 (cell wall thickness in inches), a bulk filter density of at least 0.60 g/cm3 and a volumetric heat capacity of at least 0.67 J cm−3 K−1 as measured at 500° C.

Abstract: A ceramic composite containing alkali-metal-&bgr;- or &bgr;″-alumina and an oxygen-ion conductor is fabricated by converting &agr;-alumina to alkali-metal-&bgr;- or &bgr;″-alumina. A ceramic composite with continuous phases of &agr;-alumina and the oxygen-ion conducting ceramic, such as zirconia, is exposed to a vapor containing an alkali-metal oxide, such as an oxide of sodium or potassium. Alkali metal ions diffuse through alkali-metal-&bgr;- or &bgr;″-alumina converted from &agr;-alumina and oxygen ions diffuse through the oxygen-ion conducting ceramic to a reaction front where &agr;-alumina is converted to alkali-metal-&bgr;- or &bgr;″-alumina. A stabilizer for alkali-metal-&bgr;″-alumina is preferably introduced into the &agr;-alumina/oxygen-ion conductor composite or introduced into the vapor used to convert the &agr;-alumina to an alkali-metal-&bgr;″-alumina.

Abstract: The present invention has an object to obtain a ceramic body that can support a required amount of catalyst component, without lowering the characteristics such as strength, being manufactured without forming a coating layer and providing a high performance ceramic catalyst body that is excellent in practical utility and durability.

Abstract: A porous ceramic body protected by a damage resistant hardened surface, and a method for preparing the surface hardened ceramic body. The ceramic body is protected by applying to the surface a slurry composition containing a binding agent, particles of a ceramic material, at least one boron containing compound, and a solvent. The inclusion of at least one boron containing compound in the slurry provides for hardened surfaces that are stable to higher temperatures as compared to those of the prior art.

Abstract: Transparent solid, fused microspheres are provided. In one embodiment, the microspheres contain alumina, zirconia, and silica in a total content of at least about 70% by weight, based on the total weight of the solid, fused microspheres, wherein the total content of alumina and zirconia is greater than the content of silica, and further wherein the microspheres have an index of refraction of at least about 1.6 and are useful as lens elements.

Abstract: An object of the invention is to provide a dielectric porcelain composition with low rate of phase change of a cordierite phase as a primary crystal phase, in which as a result of the low rate of phase change the dielectric constant is from 4.5 to 6 and Q value is 1,000 or more at 60 GHz, and to provide a dielectric resonator and nonradiative dielectric strip using the same. The dielectric porcelain composition comprises, as a principal component, a complex oxide having a molar composition xMgO.yAl2O3.zSiO2 (wherein 10≦x≦40, 10≦y≦40, 20≦z ≦80, and x+y+z=100), and a ratio of a (241) peak intensity &bgr;p(241) and a (222) peak intensity &bgr;p(222) of X-ray diffraction of a &bgr; phase of a 2MgO.2Al2O3.5SiO2 phase, which is a primary crystalline phase of the complex oxide, is 0.8≦&bgr;p(241)/&bgr;p(222)≦1.3.

Abstract: A spherical porous ceramic body and the production method thereof are provided. As to the porous ceramic body, the total volume of the pores having a pore radius of from 1.8 nm to 100 &mgr;m is about 0.25 cm3/g or more, the mode of pore radius of the pores is from about 1 &mgr;m to about 6 &mgr;m and the packing density is from about 0.7 g/cm3 to about 1 g/cm3. The porous ceramic body is suitably used as a carrier for a catalyst and has high mechanical strength.

Abstract: A re-usable alumina-magnesia graphite refractory suitably used for a refractory for continuous casting, such as a long nozzle used for pouring a molten metal from a ladle capable of re-use or intermittent use to a tundish, an immersion nozzle used for charging a molten metal from a tundish to a mold and a long stopper for controlling the flow rate of the molten steel; and produced by blending 3 to 60 wt % of magnesia having a particle size of 0.02 to 1.0 mm to a compound comprising mainly alumina and graphite, and kneading, molding, and baking the compound. The raw material compound comprising mainly alumina and graphite can contain spinel or zirconia.

Abstract: A dry refractory composition having superior insulating value. The dry refractory composition also may have excellent resistance to molten metals and slags. The composition includes filler lightweight material, which may be selected from perlite, vermiculite, expanded shale, expanded fireclay, expanded alumina silica hollow spheres, bubble alumina, sintered porous alumina, alumina spinel insulating aggregate, calcium alumina insulating aggregate, expanded mulllite, cordierite, and anorthite, and matrix material, which may be selected from calcined alumina, fused alumina, sintered magnesia, fused magnesia, silica fume, fused silica, silicon carbide, boron carbide, titanium diboride, zirconium boride, boron nitride, aluminum nitride, silicon nitride, Sialon, titanium oxide, barium sulfate, zircon, a sillimanite group mineral, pyrophyllite, fireclay, carbon, and calcium fluoride.

Abstract: A continuous process for the synthesis of anionic clays with carbonate and/or hydroxide anions as the charge-balancing interlayer species is disclosed. The process involves reacting a slurry comprising aluminum trihydrate and/or its calcined form, with a magnesium source. There is no necessity to wash or filter the product. It can be spray dried directly to form microspheres or it can be extruded to form shaped bodies. The product can be combined with other ingredients in the manufacture of catalysts, absorbents, pharmaceuticals, cosmetics, detergents, and other commodity products.

Abstract: An object of the invention is to provide a dielectric porcelain composition with low rate of phase change of a cordierite phase as a primary crystal phase, in which as a result of the low rate of phase change the dielectric constant is from 4.5 to 6 and Q value is 1,000 or more at 60 GHz, and to provide a dielectric resonator and nonradiative dielectric strip using the same. The dielectric porcelain composition comprises, as a principal component, a complex oxide having a molar composition xMgO·yAl2O3·zSiO2 (wherein 10≦x≦40, 10≦y≦40, 20≦z≦80 , and x+y+z=100), and a ratio of a (241) peak intensity &bgr;p(241) and a (222) peak intensity &bgr;p(222) of X-ray diffraction of a &bgr; phase of a 2MgO·2Al2O3·5SiO2 phase, which is a primary crystalline phase of the complex oxide, is 0.8≦&bgr;p(241)/&bgr;p(222)≦1.3.

Abstract: A sintered ceramic honeycomb article that exhibits an average linear coefficient of thermal expansion (25-800° C.) below about 5.0×10−7° C.−1, a total porosity between the range of 20% to about 30%, and a pore size distribution such that at least about 86% of pores are of a pore size of less than about 2 &mgr;m with the pores exhibiting a generally elongated shape oriented with their long axis in the plane of the webs, the article being made from a cordierite-forming inorganic powder batch comprising a platy talc having median particle of size less than about 2 &mgr;m, at least 4% by weight of a dispersible Al2O3-forming source having a specific surface area in excess of 50 m2/g, and one or more of the components of kaolin, calcined kaolin, silica, and corundum, each having a median particle sizes less than 5 &mgr;m.

Abstract: There is provided a method for producing a beta-alumina solid electrolyte without calcination of starting materials, according to which the step of synthesizing a magnesium-aluminum spinel starting material is not needed and a beta-alumina solid electrolyte of low resistance can be produced at lower cost. According to this method, the beta-alumina solid electrolyte is produced without carrying out calcination of the starting materials by granulating a slurry obtained by milling and mixing starting materials of an aluminum source, a magnesium source and a sodium source in water, molding the granulated product and then firing the molded product. In this method, magnesium hydroxide is used as the magnesium source and an active spinel high in reactivity is synthesized in the course of firing, and citric acid is added to the slurry as a dispersing agent.

Abstract: The invention is directed at sintered ceramic articles exhibiting a primary crystalline phase of cordierite and an analytical oxide composition, in weight percent, of 44-53% SiO2, 30-38 Al2O3, 11-16% MgO and 0.05 to 10% of a metal oxide. The ceramic article exhibits a coefficient of thermal expansion in at least one direction no greater than about 15.0×10−7° C. over the temperature range of about 25° C. to about 800° C. The sum of the weight percentages of residual mullite, corundum, and spinel, as measured by X-ray diffractometry of the crushed and powdered body, is not greater than 15%.

Abstract: An economical and environment-friendly process for the synthesis of anionic clays with carbonate and/or hydroxide anions as the charge-balancing interlayer species is disclosed. The process involves reacting a slurry including an aluminum source and a magnesium source, the aluminum source including two types of aluminum-containing compounds, preferably aluminum trihydrate and/or thermally treated calcined aluminum trihydrate. There is no necessity to wash or filter the product. It can be spray dried directly to form microspheres or it can be extruded to form shaped bodies. The product can be combined with other ingredients in the manufacture of catalysts, absorbents, pharmaceuticals, cosmetics, detergents, and other commodity products.

Abstract: The low thermal expansion and high rigidity ceramic sintered body of this invention is characterized by assuming as a crystal structure a hexagonal close-packed structure and substantially comprising solid solution crystal grains represented by the formula: MgaLibFecAldSieOf (wherein a is in the range of 1.8 to 1.9, b is in the range of 0.1 to 0.3, c is in the range of 0 to 0.2, d is in the range of 3.9 to 4.1, e is in the range of 6.0 to 7.0, and f is in the range of 19 to 23). It is further characterized by the solid solution crystal grains having lattice constants in the ranges, a0 in the range of 9.774 to 9.804 Å and c0 in the range of 9.286 to 9.330 Å, the relative density of the sintered body being of not less than 98%.

Abstract: The present invention includes a method for producing high-alumina bodies with superior chemical properties at reduced sintering temperatures. One form of the method includes the steps of providing an alumina powder precursor, adding about 2 wt. % magnesia powder precursor and about 2 wt. % titania powder precursor, mixing the resultant green powder precursor, pressing a green body from the green powder precursor, removing residual moisture and organic material from the green body, and firing the green body to about cone 13.

Abstract: A binder system for use in the formation of ceramic or other powder-formed greenware comprising a binder, a solvent for the binder, a surfactant, and a component that is non-solvent with respect to the binder and solvent. The non-solvent component exhibits a lower viscosity than the solvent when containing the binder and comprises a low molecular weight oil having a 90% recovered distillation temperature range of between about 220 to 400° C. Also disclosed is a process of forming and shaping plasticized powder mixtures and a process for forming ceramic articles utilizing the binder system.

Abstract: The present invention includes a method for producing high-alumina bodies with superior chemical properties at reduced sintering temperatures. One form of the method includes the steps of providing an alumina powder precursor, adding about 2 wt. % magnesia powder precursor and about 2 wt. % titania powder precursor, mixing the resultant green powder precursor, pressing a green body from the green powder precursor, removing residual moisture and organic material from the green body, and firing the green body to about cone 13.

Abstract: A method for producing a barium-containing composite metal oxide, comprising calcining a mixture of a barium compound and a metal compound comprising at least one metal selected from the group consisting of magnesium, aluminum, europium, manganese, strontium, calcium, terbium, zinc and titanium, or calcining a barium-containing composite metal salt comprising barium and at least one metal selected from the group consisting of magnesium, aluminum, europium, manganese, strontium, calcium, terbium, zinc and titanium, in a gas comprising a hydrogen halide and water vapor.

Abstract: A method of making a component of a ceramic discharge chamber comprising the steps of forming a ceramic composition including an aluminum powder, a binder and a grain growth inhibitor. The alumina powder has a tap density greater than 1.0 gram per cc. The ceramic composition is then die pressed to form a component preform. Next, the component preform is heated to remove at least a substantial portion of the binder.

Abstract: A binder system for use in the formation of ceramic or other powder-formed greenware comprising a binder, a solvent for the binder, a surfactant, and a component that is non-solvent with respect to the binder and solvent. The non-solvent component exhibits a lower viscosity than the solvent when containing the binder and comprises at least a portion of an organic liquid having a 90% recovered distillation temperature of no greater than about 225° C. and more preferably less than 220° C. Also disclosed is a process of forming and shaping plasticized powder mixtures and a process for forming ceramic articles utilizing the binder system.

Abstract: A ceramic comprising predominately a cordierite-type phase approximating the stoichiometry Mg2Al4Si5O18 and having a coefficient of thermal expansion (25-800° C.) of greater than 4×10−7/° C. and less than 13×10−7/° C. and a permeability and a pore size distribution which satisfy the relation 2.108 (permeability)+18.511 (total pore volume)+0.1863 (percentage of total pore volume comprised of pores between 4 and 40 micrometers)>24.6. The ceramic is suitable in the fabrication of cellular, wall-flow, diesel particulate filters having a pressure drop in kPa that at an artificial carbon soot loading of 5 grams/liter and a flow rate of 26 scfm is less than 8.9−0.035 (number of cells per square inch)+300 (cell wall thickness in inches), a bulk filter density of at least 0.60 g/cm3 and a volumetric heat capacity of at least 0.67 J cm−3 K−1 as measured at 500° C.

Abstract: The present invention is directed at sintered ceramic articles exhibiting a crystalline phase assemblage comprising, by weight, of 65-95% cordierite and 5-35% of a secondary phase selected from the group consisting of mullite, magnesium-aluminate spinel, and sapphirine and having a bulk analytical composition consisting essentially of about, by weight, 32-51% SiO2, 35-49% Al2O3, 7-16% MgO. Furthermore, the ceramic articles exhibit an effective strength of greater than about 3000, a CTE of less than about 15×10−7/° C., over the temperature range of 25° C., to 1000° C., and a total intrusion porosity, as measured by a Hg intrusion method, of at least 20%. This invention also relates to a method for producing a sintered ceramic article having the aforementioned cordierite and secondary minor phase mixture.

Abstract: A plasticizable raw material mixture for use in preparing a substrate having cordierite as its primary phase with the mixture comprised of a chemical composition, percent by weight, of 11 to 17% MgO, 33 to 41% Al2O3 and, 46 to 53% SiO2. The raw material mixture specifically comprises the following: (1) one source of Al2O3 and SiO2 comprising a clay mixture having less than about 22%, by weight based on the total raw materials in the plasticizable mixture, of calcined clay; (2) an alumina yielding precursor comprising alumina having an average particle diameter of about 1 &mgr;m or less; and, (3) at least one source of magnesia having an average particle diameter of between about 3 to 15 microns.

Abstract: A binder system for use in the formation of ceramic or other powder-formed greenware comprising a binder, a solvent for the binder, a surfactant, and a component that is non-solvent with respect to the binder and solvent. The non-solvent component exhibits a lower viscosity than the solvent when containing the binder and comprises at least a portion of a branched chain paraffin exhibiting a 90% recovered distillation temperature ranging between 205° C. to about 225° C. and a carbon chain length comprised predominantly of carbon chain distributions ranging from 12 to 14. Also disclosed is a process of forming and shaping plasticized powder mixtures and a process for forming ceramic articles utilizing the binder system.

Abstract: A process for producing a cordierite-based ceramic honeycomb structure, includes kneading raw materials for cordierite with a forming aid to obtain a raw material batch, subjecting the raw material batch to obtain a honeycomb structure, and subjecting the honeycomb structure to drying and firing in this order to obtain a ceramic honeycomb structure whose crystal phase is composed mainly of cordierite. The raw material batch contains 65% by weight or more of raw materials for cordierite, comprising talc, kaolin and aluminum hydroxide and having crystal water. The kaolin has an average particle diameter of 5 &mgr;or more and a BET specific surface area of 10 m2/g or less and is contained in the raw material batch in an amount of 10% or more by weight.

Abstract: A graphite-containing monolithic refractory material comprises at least one component selected from alumina and alumina-magnesia spinel, which are divided into selected particle size regions, artificial graphite having a selected average particle size, and pitch powder. The refractory material may optionally comprise a selected amount of silicon carbide having a selected average particle size. The graphite-containing monolithic refractory material exhibits excellent casting workability at a low moisture content, and both excellent corrosion resistance and spalling resistance. The refractory material is suitable as a casting monolithic refractory material for lining a topedo ladle car.

Abstract: Disclosed is sintered ceramic article that exhibits a primary crystalline phase of cordierite and analytical oxide composition, in weight percent, of 49-53% SiO2, 33-38% Al2O3, 12-16% MgO and exhibits a coefficient of thermal expansion no greater than about 4.0×10−7/° C. over the temperature range of about 25° C. to about 800° C. and a transverse-I ratio of not less than about 0.92. Also disclosed is a method for producing a sintered cordierite ceramic article involving preparing a plasticizable raw material, comprising a magnesium source, a SiO2-forming source and an additional component of either: (a) a clay-free, Al2O3-forming source having a surface area of greater than about 5 m2/g; or, (b) a clay and Al2O3-forming source combination wherein the clay comprises no greater than about 30%, by weight, of the total inorganic mixture, and the Al2O3-forming source exhibits a surface area of greater than about 40 m2/g.

Abstract: Low thermal expansion ceramics contains a cordierite crystal phase, wherein a phase of a crystalline compound containing at least one element selected from the group consisting of an alkaline earth element other than Mg, a rare earth element, Ga and In, is precipitated in the grain boundaries of said crystal phase, said ceramics has a relative density of not smaller than 95%, a coefficient of thermal expansion of not larger than 1×10−6/° C. at 10 to 40° C., and a Young's modulus of not smaller than 130 GPa. That is, the ceramics has a small coefficient of thermal expansion, is deformed very little depending upon a change in the temperature, has a very high Young's modulus and is highly rigid and is resistance against external force such as vibration. Accordingly, the ceramics is very useful as a member for supporting a wafer or an optical system is a lithography apparatus that forms high resolution circuit patterns on a silicon wafer.

Abstract: A ceramic filter comprising at least 50 mass % of a cordierite aggregate having a particle size of at least 74 &mgr;m and a binder, wherein said binder comprises at least 10 mass % of a fine powder of cordierite having a particle size of less than 74 &mgr;m and &bgr;-spodumene, and the mass ratio of said &bgr;-spodumene to said fine powder of cordierite is from 0.6 to 2.5, and wherein said ceramic filter has a pressure loss coefficient m′ of at least 30×10−8 cm2 as represented by the following formula and as calculated with respect to pores having diameters corresponding to at least {fraction (1/10)} of the volume-based median pore diameter: m′=(Vp/Sp)2×(&rgr;) wherein Vp (cm3/g) is a cumulative pore specific volume, Sp (cm2/g) is a cumulative pore specific surface area, and &rgr; is a cumulative porosity.

Abstract: A dielectric ceramic composition used in a high frequency band such as microwave or millimeter wave, etc., and having a low dielectric constant, low loss and small absolute value of the temperature coefficient at resonance frequency. The dielectric ceramic composition comprises Al2O3, MgO and ROn. The Al2O3, MgO and ROn are expressed by a composition formula: xAlO3/2—YMgO—zROn (R is at least one element selected from La, Ce, Pr, Nd, Sm, Eu, Gd and Tb; and n is a value stoichiometrically determined in accordance with the valence of the R), wherein x≧55, y≧0.5, z≧0.5 and x+y+z=100. A dielectric ceramic comprising a crystal phase and a glass phase also is provided. The crystal phase includes a magneto-plumbite phase that includes Al2O3.

Abstract: The present invention provides a honeycomb structure that is able to suppress separation of a loaded catalyst layer much better than the prior art, and its production process. This honeycomb structure is made in the form of honeycombs partitions having for their main component cordierite having a chemical composition of 45-55 wt % SiO2, 33-42 wt % Al2O3 and 12-18 wt % MgO, and fifty or more pores (number/1.65 mm2) having a mean diameter of 1-20 &mgr;m are provided in the surfaces of the partitions.

Abstract: The invention relates to a porous ceramic used for producing alkali ion water. The ceramic of the invention includes finely particulate zeolite having an average particle size of 0.1 to 40 &mgr;m and an alkali ion producing material as components. Besides the above components, the invention preferably comprises a fibrous mineral and/or a clay mineral. To produce the ceramic of the invention, a slurry obtained by grinding zeolite by a wet process, a slurry obtained by grinding the alkali ion producing material and the clay mineral by a wet process and a slurry obtained by grinding the fibrous mineral are first mixed and stirred to prepare a mixed slurry. This mixed slurry is then dried and fired to obtain a sintered body.

Abstract: A porous spinel type oxide shows a large surface area and a uniform micro-porous structure. The oxide is expressed by general formula MO—Al2O3 and shows a surface area per unit weight of not less than 80 m2/g. Such a porous spinel type compound oxide is obtained by impregnating a specific &ggr;-alumina carrier with a solution of a compound of metal element M capable of taking a valence of 2, drying the impregnated carrier and calcining it at a temperature of 600° C. or higher. The specific &ggr;-alumina carrier shows a surface area per unit weight of not less than 150 m2/g, a micro-pore volume per unit weight of not less than 0.55 cm3/g and an average micro-pore diameter between 90 and 200 angstroms. The micro-pores with a diameter between 90 and 200 angstroms occupy not less than 60% of the total micro-pore volume of the carrier.

Abstract: A pumpable ceramic composition is provided comprising an inorganic oxide, potassium phosphate, and an oxide coating material. Also provided is a method for preparing pumpable ceramic-based waste forms comprising selecting inorganic oxides based on solubility, surface area and morphology criteria; mixing the selected oxides with phosphate solution and waste to form a first mixture; combining an additive to the first mixture to create a second mixture; adding water to the second mixture to create a reactive mixture; homogenizing the reactive mixture; and allowing the reactive mixture to cure.

Abstract: A method for preparing high strength and high thermal shock-resistant china for ceramic whiteware which comprises the steps of molding a china-forming raw material which mainly comprises a natural ore material capable of forming corundum through firing or a material obtained by calcining the natural ore material to form corundum, a natural ore material capable of forming mullite through firing or a material obtained by calcining the natural ore material to form mullite, a clayey material and a flux such as feldspar, nepheline or dolomite; and then firing the molded china-forming raw material. The method permits the production of cheaper china for ceramic whiteware having high strength and excellent thermal shock resistance as compared with those prepared by the conventional techniques.

Abstract: This invention is directed to ceramic metal composite useful as a refractory and having improved abrasion, corrosion, and oxidation resistance. The ceramic metal composite of the present invention is comprised of ceramic refractory aggregate, metal particulate, and a nonaqueous binder wherein the ceramic refractory aggregate, metal particulate, and binder residuals react to form a three-dimensional ceramic-metal matrix. The ceramic-metal matrix is further stabilized by bonds between the metal particulate, reaction products of the metal particulate, and the ceramic refractory aggregate.

Abstract: The present invention relates to a protection tube for protecting heaters and sensors used in melting furnace for reprocessing of incinerator ash, other melting furnace, and various other furnaces, the protection tube being excellent in resistance to heat and resistance to corrosion so as to be usable favorably for a long period. The heat- and corrosion-resisting protection tube is formed in a tubular body closed at an end, being composed of ceramics, and the ceramics have a softening point over 1700.degree. C. in the air atmosphere, a three-point bending strength of 150 MPa or more at 1450.degree. C., a resistance to heat shock of .DELTA.T of 150.degree. C. or more by water quenching method, and a mean grain size of 2 .mu.m or more, having a composition of 50 mol % or more of Al.sub.2 O.sub.3 and 50 mol % or less of MgO.

Abstract: Cordierite body of CTE at 25-800.degree. C. of .ltoreq.4.times.10.sup.-7 C, at least 85% of porosity having pore diameter of 0.5-5.0.mu.; or >4-6.times.10.sup.-7 C.sup.-1, porosity at least 30 vol %, at least 85% of porosity has pore diameter 0.5-5.0.mu.. Raw materials talc, Al.sub.2 O.sub.3 source, and kaolin, calcined kaolin, and/or silica, and optionally spinel, particle diameter of talc .ltoreq.3.0.mu., of Al.sub.2 O.sub.3 source <2.0.mu., kaolin is <35 wt % of raw materials when particle diameter is <2.0.mu., are blended with vehicle and aids into plastic mixture. Green body is formed, dried, fired at 1370.degree. C.-1435.degree. C. When particle diameter of talc is <2.0.mu., and Al.sub.2 O.sub.3 source is <20 wt % of raw materials, and dispersible high surface area Al.sub.2 O.sub.3 source having particle diameter of <0.3.mu., is <5.0 wt % of raw materials, and particle diameter of kaolin is <2.0.mu., heating rate from 1150.degree. C.-1275.degree. C. is >200.degree. C./hr.

Abstract: Low expansion, low porosity cordierite bodies having a CTE at 25-800.degree. C. of <4.times.10-7C-1 and total porosity of <20%, or CTE of >4.times.10-7C-1 but <9.times.10-7C-1 and total porosity of <12%, or a CTE of >9.times.10-7C-1 but <15.times.10-7C-1 and total porosity of <10%. They are produced by selecting cordierite-forming raw materials in specific combinations of talc, spinel, kaolin, calcined kaolin, Al203-forming material, MgO-forming materials, and silica, in various particle size combinations. The raw materials are intimately blended with an effective amount of vehicle and forming aids and plastically shaped into a green body that is dried and fired at a temperature of about 1370.degree. C. to 1435.degree. C. Firing schedules vary according the raw material combination.

Abstract: Disclosed is an alumina-based sintered material comprising a magnesium component, a calcium component, a silicon component, and a lithium component, wherein the content of the lithium component in terms of oxide amount is from 0.002 to 0.04% by weight based on the alumina-based sintered material.

Abstract: In the ceramics having a low heat conductivity, silicon nitride is contained as a main component, a composite oxide or a separate phase thereof and transition metal elements having 66 to 75 of atomic number are dispersed into a substrate, and a minute layer grown continuous to the substrate is formed on the surface of the substrate. The composite oxide is at least one of 3Al.sub.2 O.sub.3. 2SiO.sub.2, 2MgO.2Al.sub.2 O.sub.3.5SiO.sub.2, 2MgO.SiO.sub.2 and 4MgO.5Al.sub.2 O.sub.3.2SiO.sub.2. The adding quantity of the composite oxide and the separate phase thereof is 15 to 60 wt. % in terms of the composite oxide. The adding component of transition metal elements having 66 to 75 of atomic number is less 10 wt. % in terms of oxide of the transition metal elements.

Abstract: There is a process for producing spherical metal-oxide powder particles. They are used as finely ground raw and filler materials in mineral, ceramic and refractory construction, technical and auxiliary materials, as well as for polishing and grinding agents.

Abstract: This invention relates to cement-free refractories exhibiting high green strength, improved corrosion resistance, and improved magnesium oxide hydration resistance useful as refractory castables for steel ladles, slag contact areas, ladle sidewalls and bottoms, and the like and as precast refractory shapes, such as well blocks, nest blocks, and the like. More particularly, this invention is directed hydraulically-bonded monolithic refractories containing a calcium oxide-free binder comprised of a hydratable alumina source and magnesium oxide and which exhibit high green strength, improved corrosion resistance, improved magnesium oxide hydration resistance, and controllable work and set times.

Abstract: The present invention relates to a refractory binder that comprises a mixture of aqueous phosphate and silica sol. The silica sol has been found to gel and set in a surprisingly effective and useful way. Preferably, the refractory binder further incorporates a small amount of magnesia as an accelerator. The present invention also provides a method of binding a refractory material such, for example, as alumina, zirconia mullite or aluminium silicate by using a refractory binder according to the invention.