Abstract: The use of a three-component water-soluble polymer comprising 5–90% by weight of a component a), preferably of the maleic acid, fumaric acid or itaconic acid type, 5–90% by weight of a component b) essentially from the group consisting of 2-acrylamido-2-methylpropanesulfonic acid, vinylsulfonic acid and vinylphosphonic acid, and 5–90% by weight of a component c) comprising acrylic acid, methacrylic acid, acrylamide or methacrylamide, as fluidizer for refractory compositions comprising alumina cement is described. The copolymer, which has a preferred molecular weight Mw of <50,000, can also be combined with further quality-improving additives such as silica, lime or soda and further customary additives for refractory compositions.

Abstract: A mixture, in particular for the production of fireproof molded bodies, including a fireproof metal oxidic main component, and an elastifying component containing a mineral emery. If needed, a binder component such as lignin sulphonate is added. A method is provided for the production of the mixture.

Abstract: The present invention relates to a method of producing particles having a particle size of less than 100 nm and surface areas of at least 20 m2/g where the particles are free from agglomeration. The method involves synthesizing the particles within an emulsion having a 1-40% water content to form reverse micelles. In particular, the particles formed are metal oxide particles. The particles can be used to oxidize hydrocarbons, particularly methane.

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 comprising an aluminum source and a magnesium source, the aluminum source comprising 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 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: Compositions, articles and methods for making such articles are disclosed. The compositions, articles and methods include calcium aluminate materials having a low coefficient of thermal expansion.

Abstract: Powdered material, the binder phase of which mainly consists of a cement-based system, which powdered material has the capacity following saturation with a liquid reacting with the binder phase to hydrate to a chemically bonded ceramic material, preferably for dental purposes. According to the invention the powdered material has a composition and/or structure suitable for giving the ceramic material translucence in the hydrated state. The invention also relates to the ceramic material produced by hydration of the powdered material.

Abstract: Powdered material, the binder phase of which mainly consists of a cement-based system, which powdered material has the capacity following saturation with a liquid reacting with the binder phase to hydrate to a radiopaque and chemically bonded ceramic material. According to the invention, said binder phase mainly consists of CaO.Al2O3 (ss) and/or 3CaO.Al2O3 (ss). The material also contains one or more heavy atom types with a density over 5 g/cm3. The invention also relates to a method for manufacturing the powdered material and the chemically bonded ceramic material formed from the powdered material, in which said binder phase has a mol ratio Al2O3.3H2O (ss) to 3CaO.Al2O3.6H2O (ss) of a maximum of 2:1.

Abstract: Ceramics comprising filler crystal particles having an average particle diameter of not smaller than 2.5 &mgr;m and a matrix crystal phase present on the grain boundaries of the filler crystal particles, the filler crystal particles being Al2O3 and the matrix crystal phase being diopside-type oxide crystals precipitated from the crystallized glass. The ceramics has a dielectric loss tangent at 60 to 77 GHz of not higher than 50×10−4, and can be effectively used as an insulating substrate in a wiring board for transmitting high-frequency signals.

Abstract: A light-transmitting (fluorescent) sintered body formed of specific substances different from the prior art materials, solving problems that the performance or efficiency, uses and manufacturing methods are limited which have not been solved with the prior art light-transmitting sintered body and which provides a light-emitting tube and an electric discharge lamp using a light-transmitting (fluorescent) sintered body formed of the specific substance. Provided are a light-transmitting sintered body mainly formed of a compound having a Mugnetplumbite structure or a &bgr;-alumina structure except for aluminum oxide, a light-transmitting sintered body mainly formed of a compound containing rare earth elements with an ionic valence of two, aluminum element and oxygen element as main components and an light-transmitting sintered body formed of mainly of a compound containing elements with an ionic valence of two except for rare earth elements, rare earth elements and oxygen element as main components.

Abstract: Disclosed is a ceramic material which is suitable for coating a body by way of a thermal spraying method and which has a coefficient of longitudinal thermal expansion that may be matched to that of a metal. The ceramic material includes 10 to 95% by weight of MgAl2O4, 5 to 90% by weight of MgO, up to 20% by weight of Al2O3, remainder standard impurities, and has grains of MgO which are embedded in a matrix of MgAl2O4.

Abstract: The invention relates to insulating material and to a method for coating nozzles, pouring spouts, pouring-stream protective tubes and similar tools for casting or converting melts, especially molten baths used in the steel industry. The aim of the invention is to produce a low-cost insulation which does not damage people's health, is not harmful to the environment, is thermally stable at operating temperatures especially at temperatures of over 1200° C.—and which exhibits low thermal conductivity. The insulation material is a mixture of at least one raw material and at least one binding agent. Said mixture forms a microporous structure once it has hardened. The surface of a workpiece for forming the insulation is at least partially coated with the insulating material.

Abstract: Compositions, articles and methods for making such articles are disclosed. The compositions, articles and methods include calcium aluminate materials consisting essentially of a main phase of CaAl4O7 and having a low coefficient of thermal expansion produced by utilizing an additive and firing to temperatures below about 1600°0 C.

Abstract: Methods of making ceramic bodies are disclosed. The methods include manufacturing calcium aluminate material having a low coefficient of thermal expansion.

Abstract: A ceramic support element for a NOx trap which includes a NOx storage component comprising an alkali metal, the ceramic support having a composition lying within a ternary system selected from the group consisting of Al2TiO5—MgTi2O5—MgAl2O4 and Al2TiO5—FeTiO5—Al2O3, a coefficent of thermal expansion (22-800° C.) of less than 20×10−7/° C. and a modulus of rupture as measured on a solid rod of circular cross section of greater than 1000 pounds per square inch.

Abstract: Compositions, articles and methods for making such articles are disclosed. The compositions, articles and methods include calcium aluminate materials having a low coefficient of thermal expansion.

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 low-temperature firing ceramic composition contains Sr2MgSi2O7 crystals forming a major crystal phase of the composition. This composition can be produced, for example, by a process including the steps of (a) mixing together a silica powder, a magnesia powder and a strontium oxide powder to obtain a powder mixture; (b) subjecting the powder mixture to a calcination at a temperature of 1,000-1,200° C. to obtain a calcination product containing Sr2MgSi2O7 crystals; (c) mixing the calcination product with alumina powder, boron oxide powder, lithium oxide powder, binder and ethanol to obtain a powder mixture; (d) granulating the powder mixture; (e) shaping the resulting granules into a green body; (f) compacting the green body by a hydrostatic pressing (CIP); and (g) firing the resulting compact in an atmosphere of air, thereby obtaining the composition.

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 method of making a cristobalite-free, mullite grain capable of withstanding reaction with molten aluminum, comprising the steps of: producing a clay slurry comprised of water and kaolin clay of a specific particle size; mixing a water insoluble barium or strontium containing compound into the clay slurry in an amount wherein the barium or strontium containing compound content of the slurry is equal to about 8% by weight of the kaolin clay in the slurry; removing sufficient water from the slurry to form a material having an pelletizable consistency; forming the material into pellets; heating the pellets by continuously moving them through a furnace having a zone, wherein the material is exposed to temperatures of at least 2,650° F. (1,455° C.) for at least 30 minutes.

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 catalyst for treating an exhaust gas stream comprising an alkaline earth/transition metal oxide component in combination with an alkaline earth/support component.

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: The present invention relates to a method of producing particles having a particle size of less than 100 nm and surface areas of at least 20 m2/g where the particles are free from agglomeration. The method involves synthesizing the particles within an emulsion having a 1-40% water content to form reverse micelles. In particular, the particles formed are metal oxide particles. The particles can be used to oxidize hydrocarbons, particularly methane.

Abstract: A method of making a cristobalite-free, mullite grain capable of withstanding reaction with molten aluminum, comprising the steps of: producing a clay slurry comprised of water and kaolin clay of a specific particle size; mixing a water insoluble barium or strontium containing compound into the clay slurry in an amount wherein the barium or strontium containing compound content of the slurry is equal to about 8% by weight of the kaolin clay in the slurry; removing sufficient water from the slurry to form a material having an pelletizable consistency; forming the material into pellets; heating the pellets by continuously moving them through a furnace having a zone, wherein the material is exposed to temperatures of at least 2,650° F. (1,455° C.) for at least 30 minutes.

Abstract: Method for manufacturing a plate boehmite and a plate alumina having high catalytic activity. The plate boehmite is prepared by subjecting at least one kind of an alkaline earth metal compound, which is selected from calcium, strontium and barium, and aluminum hydroxide to pressurization and heating at 150 to 300° C. in the presence of water. The resulting reaction product is treated with an acid to remove the residual alkaline earth metal compound contained in the product, followed by rinsing with water. The resulting plate boehmite is subjected to calcination at 450 to 1500° C. Thus, a plate alumina comprising a mixture of &thgr;-alumina and &dgr;-alumina as a major component is prepared.

Abstract: A barrier layer for a silicon containing substrate comprises an alkaline earth aluminosilcate and an additive component capable of forming a reaction product with silica.

Abstract: In insulator including alumina as a main component, a Na component in the insulator is set in the range of 0.07 to 0.5 wt % as Na2O. While the Na component content is as high as to have conventionally been regarded to be beyond the common sense, with this range of the Na component content, insulation resistance, mechanical strength and the like at high temperature are unexpectedly not reduced and an insulator with performances comparable to those of an insulator from conventional low soda alumina lower in Na component content than the above described range can be obtained. As a result, medium soda alumina and regular soda alumina that are much lower in cost than conventionally used low soda alumina can be used instead of the low soda alumina, so that dramatic reduction in production costs of insulator 2 for a spark plug 100 and in addition, of the spark plug 100 using the insulator 2 are realized.

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: Economical and environment-friendly processes for the synthesis of anionic clays and anionic clay-like materials with acetate anions as the charge-balancing interlayer species are disclosed. The processes involve combining a slurry of a gibbsite or its thermally treated form with a slurry or solution of a magnesium source and magnesium acetate. The product is not washed, needs no filtration and exists in a close-to-neutral pH condition. The product can be spray dried directly to form microspheres, or it can be extruded to form shaped bodies. Because of the absence of foreign salts, the product can be combined with other ingredients in the manufacture of catalysts, absorbents, pharmaceuticals, cosmetics, detergents and other commodity products that contain anionic clays.

Abstract: A flame spray mending material effective for applying a dense thermal spray mending layer to a silica brick wall of an industrial furnace, having a high crystallization ratio immediately after thermal spraying in a broad thermal spray condition, having an oxide concentration of 89% by weight or more of SiO2, more than 2.0 to 4.0% by weight of Na2O and/or more than 0.2 to 4.0% by weight of Li2O, having a 80% or more crystallization ratio after thermal spraying and 200 kgf/cm2 or more compression strength. A slight amount of CaO may be present to make a flame spray mending material with an oxide concentration of 89% by weight or more of SiO2, more than 2.0 to 5.0% by weight of CaO, 0.5 to 4.0% by weight of Na2O and/or more than 0.2 to 4.0% by weight of Li2O, and 1.0% by weight of less of Al2O3.

Abstract: Ceramics comprising filler crystal particles having an average particle diameter of not smaller than 2.5 &mgr;m and a matrix crystal phase present on the grain boundaries of the filler crystal particles, the filler crystal particles being Al2O3 and the matrix crystal phase being diopside-type oxide crystals precipitated from the crystallized glass. The ceramics has a dielectric loss tangent at 60 to 77 GHz of not higher than 50×10−4, and can be effectively used as an insulating substrate in a wiring board for transmitting high-frequency signals.

Abstract: Disclosed is a high-efficiency stress-luminescent material capable of emitting luminescence by receiving a mechanical stress such as compression, shearing and rubbing. The stress-luminescent material is an alkaline earth aluminate of a non-stoichiometric composition deficient in the content of the alkaline earth element by 0.01 to 20% by moles from stoichiometry. The efficiency of stress-luminescence emission can be further enhanced when the non-stoichiometric alkaline earth aluminate contains 0.01 to 10% by moles of rare earth metal ions or transition metal ions. The stress-luminescent material is prepared by subjecting a non-stoichiometric composite oxide of aluminum oxide and an alkaline earth oxide to a calcination treatment at 800 to 1700° C. in a reducing atmosphere.

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: An improved porous ceramic article and a method for forming such porous ceramic article. A mixture of ceramic particles and pliable organic hollow spheres is prepared in a liquid, typically as a suspension. The article is formed by pressing, slip casting, extruding or injection molding the mixture. The article is dried to remove the liquid, and then is fired so that the ceramic particles are bonded such as by sintering, and the organic spheres are burned off, resulting in a strong porous ceramic article having uniformly spaced interconnected voids.

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: Disclosed is a novel ceramic-glass composite material useful as a material of electronic parts for attenuation of noise components in the GHz range. The composite material is a sintered body obtained by a heat treatment of a powder blend consisting of 35-55% by weight of a hexagonal ferrite of the formula Ba.sub.3 M.sub.2 Fe.sub.24 O.sub.41 (M.dbd.Co, Ni and/or Zn) and the balance of a glass material consisting of SiO.sub.2, Al.sub.2 O.sub.3, SrO, CaO, MgO and B.sub.2 O.sub.3, of which the content of SrO is 15-25% by moles, at a relatively low sintering temperature of 850-920 .degree. C. for 10-30 minutes.

Abstract: Phosphates can be removed from a hydrocarbon stream by contacting said stream with a ceramic formed of a basic material which is insoluble in the hydrocarbon stream. A ceramic as used in this patent document is a solid solution formed by calcination of a compound. The removal of the organic acid is accomplished at temperatures ranging from 20.degree. C. to 400.degree. C., a preferred temperature is between 200.degree. C. and 370.degree. C. A hydrocarbon stream consists of C.sub.5 + hydrocarbons. The basic material can be made up of one or more alkaline earth oxides, alkaline earth compounds, alkaline metal compounds, group IIIA element compounds, group IVA element compounds, group VIA element compounds. Preferred alkaline earth oxides are sodium, magnesium, potassium, calcium, aluminum and silicon. The support for the basic material can be made from any inorganic oxide.

Abstract: A process for producing monoclinic celsian comprising the steps of forming a mixture of an alkoxide of silica, an alkoxide of aluminum, and a salt of barium; adding a catalyst of a fluorine containing compound to the mixture; calcining the catalyzed mixture; and, heat treating the calcined mixture. This process uses a sol-gel process to progressively increase the amount of monoclinic phase in relation to the hexagonal celsian. Additionally, a process for producing monoclinic strontium aluminosilicate is disclosed.

Abstract: A novel method for joining aluminum nitride-series substrates to each other is provided in the substantial absence of an intervening third layer at the joining interface between the substrates. In the method, the aluminum nitride-series substrates are joined to each other by interposing a joining agent between the substrates, heating the substrates and the joining agent to a first temperature range of at least the melting point of the joining agent to melt the joining agent and liquefy particles of the aluminum nitride at the neighborhood of the interfaces between the melted joining agent and the substrates, and then heating the joining agent and the substrates to a temperature range higher than the temperature range of the first process but lower than the melting point of the substrates to exhaust the joining agent from between the substrates.

Abstract: The present invention is directed to a dry phosphate cement mixture and process for manufacture of same. The dry mixture includes at least Al(H.sub.2 PO.sub.4).sub.3, a group IIA metal bonded to oxygen, and an aggregate. The process for manufacturing cement includes associating the dry reagent with a substantially polar solvent, such as water. The total reagent concentration is formulated such that only nominally exothermic reactions are observed. The process accommodates variable setting times and provides resulting concrete which exhibits formidable structural integrity.

Abstract: A powdered mixture of chemicals for forming a refractory composition, including a filler consisting of refractory particles, metal particles and metal peroxide containing particles, wherein the metal peroxide containing particles have a calcium peroxide content of at most 75 wt %, a magnesium peroxide content of at most 30 wt %, a barium peroxide content of at most 92 wt %, and/or a strontium peroxide content of at most 90 wt %. A refractory composition prepared from said mixture, a method for forming said composition and a method for using same are also disclosed.

Abstract: A ceramic filter for filtering molten metals includes aggregate particles consisting of fused alumina and/or sintered alumina, and a binder material, wherein the binder is present in an amount of 10 to 22 parts, by weight, per 100 parts of the aggregate particles. The binder material consists of 15 to 25%, by weight, of Al.sub.2 O.sub.3, 35 to 52% of B.sub.2 O.sub.3, not less than 7% and less than 15% of Sio.sub.2, and the balance of MgO. The ceramic filter may be prepared by kneading 100 parts of aggregate particles consisting essentially of either or both of fused alumina and sintered alumina, 10 to 22 parts of the foregoing binder material, an appropriate amount of an organic binder and an appropriate amount of water; molding the resulting mixture; drying the molded mixture; and then firing the same at a temperature ranging from 1150 to 1300.degree. C.

Abstract: A portable device for carrying with the human body includes a far infrared ray generating composition plate, a magnetic radiating unit, an electronic circuit unit, and a mercury battery disposed on the far infrared ray generating composition plate for self-radiating bioenergy so as to eliminate and reduce human fatigue and stress. The composition of the plate including 24-27 parts by weight of SiO.sub.2, 53-55 parts by weight of Al.sub.2 O.sub.3, 13-15 parts by weight of CaO, 1-4 parts by weight of MnO, 1-3 parts by weight of TiO.sub.2, and 1-2 parts by weight of Ag, the sum of the SiO.sub.2, Al.sub.2 O.sub.3, CaO, MnO, TiO.sub.2, and Ag equalling 100 parts by weight.

Abstract: A granular ceramic is prepared by firing a powder of a natural zeolite mineral, a pre-fired powder composed of shell fragments, a pre-fired powder of a silica-alumina mineral, and a copper oxide powder. When used as a fuel additive, the ceramic makes it possible to improve the combustion efficiency of hydrocarbon oils, especially of petroleum products such as gasoline, gas oil kerosene, and heavy oil, as well as to reduce CO.sub.2 and NO.sub.x emissions in exhaust gases discharged during combustion.

Abstract: This moldable refractory composition is intended to be used in the production of cast refractory pieces resistant to molten metals, especially molten aluminum. It comprises 8 to 25% by weight of an aqueous phosphoric acid solution having a concentration of phosphoric acid ranging from 40 to 85% by weight, with up to 50% of the primary acidic function of the acid phosphoric acid neutralized by reaction with vermiculite. It also comprises from 75 to 92% by weight of a mixture containing wollastonite and an aqueous suspension containing from 20 to 40% by weight of colloidal silica. The weight ratio of the aqueous suspension to the wollastonite within the mixture ranges from 0.5 to 1.2. The composition according to the invention is particularly interesting in that it can be unmolded within a very short period of time that is less than 2 hours and can be as small as 10 minutes.

Abstract: A ceramic and method of producing the same are disclosed, the ceramic having as principal ingredients natural zeolite and shells, wherein silver nitrate, magnesium oxide, potassium oxide, sodium oxide selenium oxide and ferric oxide are added thereto, and the resultant mixture fired to produce a granular ceramic. The granular ceramic enables the production of deoxidized water having an appropriately low oxidation reduction potential, for use as drinking water and the like.

Abstract: An object of the present invention is to provide a novel ceramic composite that has not only excellent dynamic characteristics, but also good electromagnetic characteristics, typified by dielectric characteristics, and the present invention relates to a ceramic composite, characterized in that an oxide having a perovskite structure which includes as raw materials lead and/or an alkaline earth metal is dispersed in a ceramic matrix, and in the above-mentioned ceramic composite, preferably the ceramic matrix is MgO, MgAl.sub.2 O.sub.4, or ZrO.sub.2, and also, preferably in the above-mentioned ceramic composite, the perovskite structure oxide particles are covered with MgO, MgAl.sub.2 O.sub.4, or ZrO.sub.2, and the ceramic matrix is Al.sub.2 O.sub.3.

Abstract: An alumina sintered body containing, as impurities, sodium oxide, potassium oxide, silicon oxide, calcium oxide, ferric oxide and titanium oxide in a total amount in the range from 100 to 10000 ppm, in which a total amount of the sodium oxide and potassium oxide based on the total amount of the impurities is not more than 4 wt. %. In the manufacture of the sintered body, its starting powder is admixed with at least an acid compound to produce metal salts by a reaction of the acid compound with metals contained in the starting powder and the resulting metal salts are removed.

Abstract: Composition for a coating protecting the surfaces of carbon-containing products exposed to a hot, oxidizing environment such as the parts of anodes not immersed in the molten salt bath and the liners of the aluminum electrolysis cells and more generally the non-immersed parts of carbon-containing refractory elements used in electrolysis conducted below 950.degree. C. in a molten salt bath, comprising a geopolymer, preferably in the fluoropoly(sialate-disiloxo) family, the other components possibly being water as well as alumina and/or a refractory other than silica. Coating protecting the surfaces of carbon-containing products exposed to a hot, oxidizing environment such as the non-immersed parts of carbon-containing refractory elements used in electrolysis conducted below 950.degree. C. in a molten salt bath, including polysilicates and at least one inorganic polymer in the poly(sialate) family, preferably fluoropoly(sialate-disiloxo), also possibly with alumina or another refractory other than silica.