Abstract: A composite substrate is provided, which comprises a cordierite-anorthite-boron base composite material and has a microstructure with anorthite included in the cordierite phase. This substrate can be used in the form of a circuit substrate, because it has high-enough mechanical strength, a coefficient of thermal expansion close to that of silicon and a decreased dielectric constant and, moreover, can be sintered at a low temperature.

Abstract: Disclosed herein are a refractory material of high-purity electrofused magnesia clinker having good resistance to corrosion by slag, especially the slag with a high iron content, at high temperatures under an oxidative environment, and a burned or unburned refractory brick made of such refractory material of high corrosion resistance, which is superior in corrosion resistance as well as spalling resistance.The refractory material comprises more than 10 wt. % of electrofused magnesia clinker containing 98.0 to 99.8 wt. % of MgO, less than 0.05 wt. % of SiO.sub.2, and 0.1 to 2.0 wt. % of CaO. It may be in the form of burned or unburned or prepared unshaped refractories.

Abstract: Described are sintered silicon nitride bodies useful as materials for parts required to have strength, especially excellent impact strength for items such as automobile parts and machine parts. The sintered Si.sub.3 N.sub.4 bodies contain 80-98 wt. % of silicon nitride and have a porosity not higher than 3% and an shock compressive elasticity limit of at least 15 GPa.

Abstract: Ceramic products consisting principally of cordierite and a method for making them are provided, the method employing batches comprising a mineral component and a chemical component, the mineral component comprising clay and talc and the chemical component consisting essentially of a combination of the powdered oxides, hydroxides, or hydrous oxides of magnesium, aluminum and silicon. Ceramics made by extrusion and firing of the batches can exhibit low porosity, high strength and low thermal expansion coefficients.

Abstract: Disclosed is a porous sepiolite having an improved water-resistance and thermal shock resistance obtained by grinding, moisture-conditioning and molding sepiolite, and then calcining said molded sepiolite at a temperature in the range of about 650.degree. C. to about 800.degree. C. Also disclosed is a porous sepiolite having a large specific surface area, wherein the pores having a pore diameter of 50 angstroms or less have a specific surface area in the range of from 40 to 200 m.sup.2 /g and in which no less than 20% of the total surface of the sepiolite is occupied with the pores having a pore diameter of 50 angstroms or less and wherein the pore distribution curve of the sepiolite has a main peak at a pore diameter of no more than 50 angstroms. This sepiolite is obtained by grinding, moisture-conditioning and molding sepiolite, calcining the same at a temperature in the range of about 650.degree. to about 800.degree. C., and then subjecting said calcined sepiolite to an acid treatment.

Abstract: A self-fluxing binder composition for use in the pelletization of an ore concentrate, especially iron ore concentrates. The composition comprises from 50 to 98% by weight of one or more carrier having a high surface area, and from 2 to 50% by weight of a water soluble organic enhancer. The carrier is selected from the group consisting of natural and synthetic magnesium and/or calcium bearing minerals and preferably consists of synthetic, fibrous-like forsterite. The enhancer is selected amongst the natural polysaccharides, of high viscosity, and more preferably amongst the natural gums of high viscosity such as the guar or xanthan gum and amongst starch and is derivatives. The use of such a self-fluxing binder composition improves the properties of the green and dry pellets and makes them more easy to handle, as compared to those produced with other conventional binders. Moreover, the pellets that are produced with such a binder composition have improved metallurgical properties.

Abstract: The occurrence of efflorescence has been reduced or eliminated in ceramic articles formed from a novel vitreously bonded cement-containing composition. The articles also exhibit improved strength, reduced firing shrinkage and increased frost resistance. The articles are produced by combining hydraulic cement containing calcium silicate and/or calcium aluminate components, vitrifiable inorganic powders forming molten liquid-flowing substances, and reactive or sinterable mineral powders selected from the group consisting of magnesium silicates, aluminum silicates and mixtures thereof; combining the ingredients with water to form a mixture; molding the mixture into an article; hardening the article by hydration; and firing the molded article to a maximum temperature of between about 1000.degree. C. to 1400.degree. C.

Abstract: A refractory adhesive and filler paste composition is described which can be extruded, trowelled or parged onto a refractory surface. The composition can be used to adhesively secure shaped refractory articles together or used as a filler. The composition contains refractory grain particles having critical size limitations and a non-aqueous binder system which includes an unsaturated drying oil such as tung or linseed oil and an organic solvent such as naphtha. The composition may be premixed and packaged in a caulking gun cartridge and applied by extrusion.

Abstract: A composition for multilayer ceramic substrates and dielectric materials with low firing temperatures is disclosed. The composition, based on the total weight of the composition, includes 40-80% of amorphous borosilicate glass which contains 60-80% by weight of SiO.sub.2, 15-30% by weight of B.sub.2 O.sub.3, 0.5-1.5% by weight of Al.sub.2 O.sub.3 and 0.5-3% by weight of alkali oxides; and 20-60% of fillers selected from the groups of alumina, forsterite, quartz, fused SiO.sub.2, mullite, cordierite, BN, and AlN.

Abstract: Basic monolithic refractories of which the chemical composition consists essentially of, in oxide equivalence, 65%-96% by weight of MgO, 2.6%-20% by weight of ZrO.sub.2, 1.3-10% by weight of SiO.sub.2, 2% or less by weight of CaO, 0.5% or less by weight of Fe.sub.2 O.sub.3 and 1% or less by weight of Al.sub.2 O.sub.3, and with a mineral composition containing periclase as the main component and cubic zirconia and forsterite as sub-components, and with apparent porosity of 7% or less and bulk density of 3.2 g/cm.sup.3 or more.Basic monolithic refractories under this invention possess excellent slaking resistance, slag erosion resistance, slag penetration resistance and spalling resistance. They exhibit an excellent service life, especially as lining material for steel-making furnaces.

Abstract: The present invention is a method for producing swellable or nonswellable fluorine mica at a relatively lower temperature by heating a powdery mixture comprising 10 to 35% by weight of an alkali silicofluoride as the main component optionally together with an alkali fluoride and the balance of talc. This fluorine mica is used for pigments, etc.

Abstract: A light transmitting sintered body of cordierite has a composition equal or close to the stoichiometric composition of cordierite which is represented as 2MgO.2Al.sub.2 O.sub.3.5SiO.sub.2, consists mainly of a phase of cordierite crystals, and has a total transmittance of at least 20%. A method of preparing it is also disclosed.

Abstract: Disclosed is a process for the preparation of an anorthite sintered body, which comprises preparing a formed body of at least one powder selected from the group consisting of (i) a calcium type zeolite having an SiO.sub.2 /Al.sub.2 O.sub.3 molar ratio lower than 3, (ii) an amorphous calcination product obtained by calcining said calcium type zeolite and (iii) a mixture of said calcium type zeolite or said amorphous calcination product and an alkaline earth metal compound, and sintering the formed body at a temperature lower than 1000.degree. C.

Abstract: A MgO/SiC composite material in which SiC particles with nano-meter order in size are dispersed within MgO matrix grains can be prepared by hot-pressing the mixture of fine MgO and SiC powders. Addition of SiC particles in the range of 5 volume percent to 50 volume percent to the MgO matrix increased remarkably the fracture strength and the hardness in a nanometer-order structure of the composite.

Abstract: A metal oxide dielectric dense body, comprising (I) grains having a predominant crystalline phase (a) a primary metal oxide selected from the group consisting of silicon and magnesium oxide and (b) optionally a secondary metal oxide selected from the group consisting of aluminum and zinc oxide and (II) between about 1 and about 20 atom % bismuth, vanadium, or boron oxide or combinations thereof, discontinuously located at the boundaries of the crystalline grains or as inclusions in the crystalline grains, the atom %'s based on the total atoms of bismuth, vanadium, boron, silicon, magnesium, aluminum, and zinc. The dense body has a density which is at least 95% of theoretical.

Abstract: A ceramic honeycomb structure containing SiO.sub.2, Al.sub.2 O.sub.3 and MgO primarily in the form of cordierite, mullite and corundum having a compositional gradient in the direction of the channels of the honeycomb and having extensive microcracking provides high resistance to thermal shock, and is useful as a substrate for catalysts.

Abstract: A metal oxide dielectric dense body, comprising (I) grains having a predominant crystalline phase (a) a primary metal oxide selected from the group consisting of silicon and magnesium oxide and (b) optionally a secondary metal oxide selected from the group consisting of aluminum and zinc oxide and (II) between about 1 and about 20 atom % bismuth, vanadium, or boron oxide or combinations thereof, discontinuously located at the boundaries of the crystalline grains or as inclusions in the crystalline grains, the atom %'s based on the total atoms of bismuth, vanadium, boron, silicon, magnesium, aluminum, and zinc. The dense body has a density which is at least 95% of theoretical.

Abstract: This invention relates to processes for preparing ceramic articles which are especially suited for electronic applications. The process involves taking a shaped article which has been formed from a magnesium exchanged zeolite powder, the zeolite selected from the group consisting of philipsite, harmotome, gismondine, zeolite B, zeolite ZK-19 and zeolite W, and sintering it at a temperature of about 1,000.degree. C. to 1,350.degree. C. for about 1 to about 6 hours. The magnesium exchanged zeolite has a SiO.sub.2 /Al.sub.2 O.sub.3 ratio of about 2.3 to about 2.8 and a sodium content less than 0.5 weight percent. The ceramic article that is formed has a substantially crystalline cordierite phase and has a density of at least 90% of its theoretical density. A preferred process involves calcining the magnesium exchanged zeolite powder at a temperature of about 600.degree.-800.degree. C. to collapse the zeolite framework and give upon sintering a cordierite ceramic article which is substantially crack free.

Abstract: A process for the production of a magnesium oxide having high hydrolysis resistance and high fluidity, which comprises:(A) a step of reacting a water-soluble magnesium salt with an alkaline substance in such an amount that is not more than 0.95 equivalent weight based on 1 equivalent weight of the water-soluble magnesium salt, at a temperature of not more than 40.degree. C.,(B) a step of heating the resultant reaction product and its reaction mother liquor at about 50.degree. to 120.degree. C. to form a magnesium hydroxide,(C) a step of forming particles having an average secondary particle diameter of about 5 to 500 .mu.m by using a spray drier,(D) a step of firing the particles at about 1,100.degree. to 1,600.degree. C., and(E) a step of pulverizing the resultant fired product under conditions which do not substantially destroy the average secondary particle diameter obtained in the above step (C).

Abstract: A mix for forming a silicon nitride bonded magnesia refractory shape consisting essentially of; for each 100 wt. % thereof at least, about 3 to 20 wt. % of a high purity silicon powder containing no more than about 0.2 wt. % metallic impurities and, correspondingly, 97 to 80 wt. % of a high purity magnesite; and the resultant refractory shape formed after shaping of the mix and nitriding thereof and the method of making such shape.

Abstract: Stable magnesium containing silicate sols are produced by preparing a solution of silicon alkoxide and of magnesium alkoxide and optionally of aluminum alkoxide in solvent wherein the atomic ratio of Mg to Si ranges from 0.3:1 to 4:1 and simultaneously reacting said alkoxides with peroxy compound or peroxy compound and water. Water presence, rate of addition of reactant, quantity of solvent and temperature of reaction are controlled to negate formation of precipitate. For a magnesium silicate sol, preferably the silicon alkoxide is tetraethylorthosilicate, the magnesium alkoxide is magnesium methoxide, the solvent is methanol and 30% H.sub.2 O.sub.2 is used as a reactant. For a magnesium aluminosilicate sol, preferably the silicon alkoxide is tetraethylorthosilicate, the magnesium alkoxide is selected from the group consisting of magnesium-s-butoxide and magnesium-2-(2'-methoxyethoxy)ethoxide, the aluminum alkoxide is aluminum isopropoxide, the solvent is sec-butanol and 2-(2'-methoxyethoxy)ethanol and 30% H.

Abstract: This invention relates to processes for preparing ceramic articles which are especially suited for electronic applications. The process involves taking a shaped article which has been formed from a magnesium exchanged zeolite powder, the zeolite selected from the group consistig of phillipsite, harmotome, gismondine, zeolite B, zeolite ZK-19 and zeolite W, and sintering it at a temperature of about 1,000.degree. to 1,350.degree. C. for about 1 to about 6 hours. The magnesium exchanged zeolite has a SiO.sub.2 /Al.sub.2 O.sub.3 ratio of about 2.3 to about 2.8 and a sodium content less than 0.5 weight percent. The ceramic article that is formed has a substantially crystalline cordierite phase and has a density of at least 90% of its theoretical density. A preferred process involves calcining the magnesium exchanged zeolite powder at a temperature of about 600.degree.-800.degree. C. to collapse the zeolite framework and give upon sintering a cordierite ceramic article which is substantially crack free.

Abstract: Disclosed is a sintered ceramic body with high strength, excellent refractoriness (heat-resistance) and machinability characterized by comprising a composition of CaO-SiO.sub.2 -MgO as surrounded by the points 1, 2, 3, 4, 5, 6 and 7 in FIG. 1.Also disclosed is a method of manufacturing a sintered ceramic body with excellent refractoriness (heat-resistance) and machinability characterized by preparing a raw material composition which consists of CaO, SiO.sub.2 and MgO as surrounded by the points, 1, 2, 3, 4, 5, 6 and 7 in FIG. 1 and then firing the composition at a temperature higher than 1200.degree. C. and up to 1350.degree. C.

Abstract: A moldable composiion comprising a mixture of magnesia, alumina, and silicon carbide powders or agglomerates thereof, the powders having an overall average size of at most 5.0 micrometers, preferably an average size in the range of 0.2 to 2.0 micrometers, optionally a polymeric binder, optionally a fluxing agent, and optionally a plasticizer or lubricant which exhibits litle or no controlled dimensional stability upon being fired to a cordierite ceramic material in a novel process. The process involves incorporation of silicon carbide powder into the moldable composition and the reaction of this silicon carbide upon firing to produce silicon dioxide. The cordierite ceramic material is useful where the dimensions of a shaped or molded part must be preserved after firing, as, for example, in the preparation of dental articles or as a mold for casting metals.

Abstract: The reliability of silicon nitride bodies for use in bearings can be greatly improved by control of microstructural flaws which produce bright specular reflections when metallographically prepared surfaces of the composites are examined microscopically in low angle incident light, dark field reflected light, or reflected polarized light viewed through a crossed polarizing analyzer. The population of such flaws can be controlled by modestly increasing the normal amount of intergranular phase and longer than normal milling times before sintering. Size classification of the powder before compression also improves the performance of the body.The fatigue cycles to failure of ten percent of the silicon nitride surfaces tested at 6.9 GPa contact stress in accelerated bearing failure ASTM Test STP 771 (L.sub.

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: A high-temperature resistant blast pipe is primarily intended for delivering gas, such as oxygen, and, when appropriate, solid material to metallurgical processes, and incorporates a layer of refractory material comprising a refractory mixture of solid particles and an alkali-silicate based binder.The blast pipe is characterized in particular in that the major constituent of the binder is of the type polymerized alkali silicate.

Abstract: Process for producing monolithic ceramic articles by sintering at temperatures from about 900.degree. C. to about 1350.degree. C. a shaped zeolite charge comprised of selected zeolites with Si/Al ratios of from about 0.7 to about 5.

Abstract: A dielectric ceramic composition for high frequencies consisting essentially of a basic composition expressed by the general formula:xMgO--yAl.sub.2 O.sub.3 --zSiO.sub.2wherein x, y and z are mole percentage of the respective components, x+y+z=100, 65.ltoreq.x.ltoreq.77, 1.ltoreq.y.ltoreq.15, and 8.ltoreq.z.ltoreq.34 and an exclusive additive of 0.1 to 10.0 weight % of Li.sub.2 O. The basic composition has a set of x, y and z falling within an area defined by a polygon ABCD encompassed by the points A, B, C and D in FIG.

Abstract: A shaped, sintered magnesia article having an enhanced hydration resistance and an improved mechanical strength is produced by evenly coating fine individual magnesia particles with silica coating layers containing an organic substance in an amount of 0.01% or less in terms of carbon, based on the molar amount of silicon in the silica coating layers; by shaping the silica-coated magnesia particles into a predetermined form; and by sintering the resultant shaped silica-coated magnesia particle article at an elevated temperature to an extent such that the silica coating layers are converted to corresponding forsterite coating layers.

Abstract: The present invention resides in the provision of a basic unburned brick or castable refractory which contains none or an extremely small amount of components which exert a harmful influence on molten steel such as phosphorus, sulfur, and boron and which has a high hot strength.

Abstract: A composite ceramic extrusion die consisting of a silicon carbide wisker-reinforced cordierite ceramic wherein the predominant matrix phase is cordierite or, preferably, barium-stuffed cordierite having a crystal compositon xBaO.4MgO.(4+x)Al.sub.2 O.sub.3.(10-2x)SiO.sub.2 wherein x ranges from zero up to about 0.5, such extrusion die exhibiting excellent durability under the conditions of non-ferrous metal alloy extrusion at temperatures of 700.degree.-900.degree. C., is described.

Abstract: A spinel type ceramic sintered body is provided starting from a chromiferous slag which is a waste discharged from sodium chromate production, said sintered body being reproducable by selecting the mole ratios of R.sub.2 O/MgO to 0.9-2.0 and SiO.sub.2 /MgO to 1-6 wherein R represents collectively Al, Fe and Cr, the sintered body having high thermal conductivity falling within the range of 1.3-2.5 kcal/mh.degree. C., specific electric resistance falling within the range of 10.sup.2 -10.sup.7 cm high mechanical strengths and unique coloration and which can be used as a functional tile.

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.

Abstract: Cordierite series dense and low expansion ceramics have excellent thermal shock resistance property, being airtight, heat resistant and having high dimensional stability at high temperatures can be achieved by incorporating 2-10% by weight of P.sub.2 O.sub.5 in the cordierite ceramic and acid treating the fired or sintered body to selectively remove P.sub.2 O.sub.5 to primarily result in an amount of 0.1% by weight of P.sub.2 O.sub.5 remaining in the sintered body.

Abstract: The present invention disclosed a magnesia clinker excellent in corrosion resistance, which is useful for a magnesia carbon refractory and also for a refractory for steel manufacturing furnace, and the magnesia clinker is characterized by:(a) having a purity of MgO of 97 wt. % or higher;(b) containing 2.0 wt. % or less of CaO;(c) containing 0.01 wt. % or more of B.sub.2 O.sub.3 ;(d) containing 0.3 wt. % or less of SiO.sub.2 ;(e) containing impurities other than MgO, CaO, B.sub.2 O.sub.3 and SiO.sub.2 of 2 wt. % or less;(f) having a bulk density of 3.35 (g/cc) or higher and an apparent porosity of 3.0 (vol. %) or less; and(g) having a mean crystal size of magnesia of 100 .mu.m or larger.

Abstract: A magnesia-calcia clinker having a high density, said clinker containing MgO, CaO and Fe.sub.2 O.sub.3 as oxides, having the following chemical composition in percent by weightMgO, CaO and Fe.sub.2 O.sub.3 : at least 99% in totalMgO: at least 10%Fe.sub.2 O.sub.3 : 0.2-5%and having a density corresponding to at least 97.5% of the theoretical density. The above magnesia-calcia clinker can be produced by adding a water-soluble iron compound to sea water, bittern or brine, simultaneously with, or after, the addition of the water-soluble iron compound, adding a calcined product of dolomite, lime or a hydrate thereof to form a precipitate composed mainly of magnesium hydroxide, mixing the resulting magnesium hydroxide with a calcium compound, and dead-burning the resulting mixture.

Abstract: A silicon nitride cutting tool primarily for cutting cast iron comprises a granular phase consisting essentially of silicon nitride and an intergranular amorphous phase consisting essentially of magnesium oxide, yttrium oxide and silicon oxide wherein the components are present in specified amounts and ratios.

Abstract: Refractory lining for e.g. casting boxes comprising a refractory matrix and precipitated silica, the silica being precipitated in situ to form a structure, imparting to the material a volume weight of from about 0.8 to about 1.2 g/cm.sup.3, the material being substantially free from carbon, hydrogen and available oxygen; process for the manufacture of such refractory lining.

Abstract: Ceramic materials comprising steatite or forsterite which are highly dense in nature may be prepared by admixing a hydrolyzed alcoholic solution of a silicon alkoxide with a solution prepared by adding an organomagnesium compound to an alcohol at gelation conditions. Following the formation of the gel, it is then dried at an elevated temperature of from about 300.degree. to about 500.degree. C. to remove volatile compounds as well as to decompose any remaining organic compounds and thereafter the powder is pressed into a desired shape. The formed shape is then sintered at a temperature in the range of from about 850.degree. to about 950.degree. C. to form a densified ceramic.

Abstract: High density magnesia clinker characterized by having a chemical composition, as oxides in weight %, ofMgO: 97.5% or moreCaO: 0.8-2.0%SiO.sub.2 : 0.12-1.0%Fe.sub.2 O.sub.3 : 0.3% or lessAl.sub.2 O.sub.3 : 0.15% or lessB.sub.2 O.sub.3 : 0.03% or lesswith a bulk density of at least 3.48 g/cm.sup.3. The said high density magnesia clinker can be produced by forming magnesium oxide by calcination of naturally occurring magnesite having a composition, based on ignition in weight %,MgO: 97.5% or moreCaO: 0.8-2.0%SiO.sub.2 : traces to 0.15%Fe.sub.2 O.sub.3 : 0.3% or lessAl.sub.2 O.sub.3 : 0.15% or lessB.sub.2 O.sub.3 : 0.1% or less,grinding the same after, or with, addition of amorphous silica, silica gel or a silicon compound capable of forming SiO.sub.2 by dead-burning in such a manner as to have the SiO.sub.2 content of 0.12-1.0% after dead-burning and dead-burning.

Abstract: Molten alkaline earth metal halides are used to convert highly stable oxides into the corresponding anhydrous halides. Usually a third reactant, such as silica, is added in order to bind the basic oxide thus formed. The solid oxide compounds (e.g. silicates) which result are wellknown ceramic phases of a high degree of purity.

Abstract: There is disclosed a material for hot or plasma spraying, especially a material based on oxide ceramics, and a process for the production thereof. The composition of the invention is a mixture of powdered oxides containing at least two fundamental oxides with high melting point, and at least one glass-forming oxide the melting point of which is lower. The invention also includes a process for the production of such composition by the melting and agglomeration of individual components in the oxidizing medium of a plasma stream, including the special treatment of the starting components.

Abstract: A coating for foundry cores and molds comprising an aqueous suspension of clay, olivine, and sodium tripolyphosphate.

Abstract: Sheathed electrical heating elements containing MgO heat conductive, electrical insulating material having a high degree of calcination together with additives in the form of a clay and fumed silica to increase the electrical resistivity, density and flow properties.

Abstract: Aggregate-containing products bonded by an aluminosilicate hydrogel are disclosed. A system of two-part mixing and blending of binder components with various granular-like aggregates, modifiers and/or fillers is described in which the resulting compositions are temporarily fluid and formable for short, controllable periods of time but which thereafter become strong, rigid, adherent, erosion resistant composites, requiring little or no external heat supply to achieve full set. The compositions can be formulated for molding on suitable forms or patterns, and may also be prepared in slurry form suitable for spray coating or sealing applications. A wide variety of products can be manufactured of the compositions, including investment molds and cores for foundry use, as well as non-foundry products such as heat and electrical insulators, construction blocks, panels, coating slurries, etc. which may be of essentially solid or foamed (cellular) construction.

Abstract: A modified cordierite (2MgO.2Al.sub.2 O.sub.3.5SiO.sub.2) composition in which at least a portion of the silicon dioxide is replaced with germanium oxide. These compositions have low thermal expansion, excellent formability and thermal shock resistance making them especially suitable for the manufacture of mirror substrates to be used at elevated temperatures. By selecting the proportion of germanium oxide according to the intended operating temperature, substantially zero thermal expansion can be achieved between room temperature and the selected operating temperature. Methods of manufacturing the material and of selecting the thermal expansion characteristics are also disclosed.

Abstract: Provided by this invention is a slaking-resistant calcia refractory comprising, as a fired mixture, (a) 2% by weight or less of silicon dioxide, (b) aluminum oxide (Al.sub.2 O.sub.3) and magnesium oxide (MgO) of the amount defined in the graph of FIG. 5 as within the region enclosed by the lines connecting point A (2.5 wt % Al.sub.2 O.sub.3 and 0 wt % MgO), point B (1.5 wt % Al.sub.2 O.sub.3 and 1.5 wt % MgO), point C (1.5 wt % Al.sub.2 O.sub.3 and 8.5 wt % MgO) and point D (10 wt % Al.sub.2 O.sub.3 and 0 wt % MgO), (c) 0.9% by weight or less of iron oxide, and (d) a predominant amount of calcium oxide.

Abstract: High purity fine particle size amorphous Si.sub.3 N.sub.4 powder compacts may be pressureless sintered to high density by the addition of from 100 to 1000 parts per million Ti to the powder prior to compaction.

Abstract: Granular compositions are disclosed for use in preparing hard, water and erosion-resistant, shapes such as foundry molds and cores, that are self-setting under ambient atmospheric conditions to allow such shapes to be stripped from patterns on which they are formed, such pattern stripping being possible immediately after forming in the case of foundry cores and the like, and within controllable pattern strip times as low as 60 seconds for foundry molds. The shapes may be used without baking and, in the case of foundry molds and cores, are ready for casting molten metal within as little as one hour. Molds and/or cores free of organic materials can be formed with the novel compositions, providing essentially carbon-free surfaces at the mold-metal interface, as well as being free of other deleterious elements such as sulfur, phosphorus and boron, thereby avoiding alloy composition alteration at the interface due to migration during casting.