Abstract: A method to produce an article of commerce comprising a self-supporting ceramic body by oxidation of a molten parent metal with a vapor-phase oxidant, includes applying to a surface of the parent metal a layer at least one dopant material therein. The layer is thin relative to the thickness of the ceramic body. Upon heating the parent metal to a molten state in the presence of the oxidant, e.g., air, an oxidation reaction product is formed on the molten metal which, because of the effect of the dopant material, migrates through the growing oxidation reaction product so as to be exposed to the oxidant to form additional oxidation reaction product to and beyond the depth of the applied dopant material layer. Suitable temperature and oxidizing conditions are maintained for a time sufficient to produce a self-supporting ceramic body.

Abstract: A method of making self-supporting ceramic composite structures having filler embedded therein includes infiltrating a permeable mass of filler with polycrystalline material comprising an oxidation reaction product obtained by oxidation of a parent metal such as aluminum and optionally containing therein non-oxidized constituents of the parent metal. The structure is formed by placing a parent metal adjacent to a permeable filler and heating the assembly to melt the parent metal and provide a molten body of parent metal which is contacted with a suitable vapor-phase oxidant. Within a certain temperature region and optionally aided by one or more dopants in or on the parent metal, molten parent metal will migrate through previously formed oxidation reaction product into contact with the oxidant, causing the oxidation reaction product to grow so as to embed the adjacent filler and provide the composite structure.

Abstract: A high density, shock resistant ceramic comprising from 1 to about 4 mols of a dense spinel ceramic matrix having dispersed therein, 1.5 to 1, respectively, of a metal oxide derived from a decomposable salt of said metal and having a thermal expansion characteristic different from said dense spinel ceramic matrix and at the decomposition temperature a volume less than that exhibited by its salt form and a process for preparing same.

Abstract: A ceramic core for use in the investment casting of metals includes, prior to sintering, about 80 w/o to about 86 w/o of a ceramic filler material and about 14 w/o to about 20 w/o of a binder material. The ceramic filler material includes about 66 w/o to about 95 w/o Al.sub.2 O.sub.3 particles, about 1 w/o to about 20 w/o Y.sub.2 O.sub.3 particles, about 1 w/o to about 5 w/o of a grain growth inhibiting agent, and the balance a carbon-bearing fugitive filler material. Subsequent to sintering, the ceramic core has a microstructure characterized by the presence of substantially unreacted Al.sub.2 O.sub.3 particles having a polycrystalline composition consisting essentially of 3Y.sub.2 O.sub.3.5Al.sub.2 O.sub.3 on the surfaces of the Al.sub.2 O.sub.3 particles.

Abstract: There is disclosed a coating compositions which can be produced from (1) a reactive MgAl.sub.2 O.sub.4 spinel (2) aluminum acid phosphate moieties and phosphoric acid, (3) water, (4) optionally, non-reactive fillers, colorants and (5), also optionally, handling agents.

Abstract: A refractory mix for forming low thermal conductivity refractory shapes comprising about 50 to 90% by weight of magnesite, about 10 to 50% by weight spinel or about 7 to 35% by weight of an alumina-bearing material, and about 1 to 10% by weight of a nonsiliceous void-forming material.

Abstract: Ceramic oxide diphasic xerogels of structurally dissimilar phases (crystalline and amorphous, semicrystalline or noncrystalline) but compositionally similar phases will be converted to crystalline ceramic oxide products having enhanced densification when subjected to substantially lower sintering temperature.

Abstract: A refractory composition for use in contact with molten aluminum alloys containing a refractory aggregate, a binder and an additive for imparting aluminum resistance to the refractory composition, the additive comprising synthetic calcium fluoride containing aluminum borate aggregate consisting essentially of 10 to 50% by weight boron oxide, 10-50% by weight of aluminum oxide, and 25-75% by weight calcium flouride. The synthetic aggregate may be prepared by blending boric acid, aluminum oxide, and fluorspor and firing the resultant blend at a temperature above 800.degree. C. to form a synthetic aluminum borate having calcium fluoride contained in its insoluble structure.

Abstract: A refractory composition which is suitable for forming a sliding gate to be used at the bottom of a ladle or tundish is provided. The refractory composition comprises 10 to 30 parts by weight of an alumina-magnesia spinel material containing 40 to 70% by weight of Al.sub.2 O.sub.3, 25 to 60% by weight of MgO and 10% or less of impurities, and 70 to 90 parts by weight of a magnesia material containing at least 90% by weight of MgO, wherein the composition contains 10 to 25% by weight of Al.sub.2 O.sub.3 and 75 to 90% by weight of MgO. 1 to 10 parts by weight of Al.sub.2 O.sub.3 material may be further added together with the alumina-magnesia spinel material and the magnesia material, to form the refractory composition.

Abstract: Heavy ceramic shaped material with a content of at least one of the components magnesia, fired dolomite, chromite and spinel, characterized by a microcrack system substantially homogeneously distributed in the shaped material structure, as well as process for producing such a heavy ceramic shaped material and the use thereof.

Abstract: A cement for vessels for containing molten alloys of aluminum with metals selected from the group consisting of lithium, magnesium, zinc and copper is shown that forms a hard sintered crust for containing the molten alloy in the vessel with a backing of granular cement for controlling thermal stress while also providing a vitrifying flux means in the cement mix for effecting a sealing of any cracks that may form in the crust by reacting with any hot alloy flowing through such a crack to contain the leak as a metal spur.

Abstract: Ultrafine particles of ceramic or metallic material are obtained at low temperatures from a nitrate source capable of endothermic decomposition by molecularly combining under a nitrogen atmosphere the nitrate source with an inorganic reducing fuel compound, such as hydrazine, to provide a chemical precursor for the ceramic or metallic material and then exothermically decomposing the precursor in a controlled atmosphere by heating to a temperature up to about 200.degree. C. below the endothermic decomposition temperature of the nitrate source. The nitrate source is a metal nitrate or a mixture of nitrate salts. Ferrite particles are recovered when the nitrate source is a mixture of nitrate salts containing ferric nitrate in a 2:1 molar ratio with at least one additional metal nitrate.

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 method of producing layered structures of metal hydroxides (one or more metals) free of chloride or chlorine is disclosed. A specific ratio layered structure hydroxide is obtained from mixing first and second metals (respectively in the form of hydroxide, oxyhydroxide carbonate or nitrate as to the first metal and a hydroxide or alkali metal oxide as to the second) in proportions yielding a precipitated layered structure. The precipitators metal hydroxides with any excess of metal over 1:1 forming a segregated phase. Processing involves mixing, maintaining as a suspension up to about 48 hours at temperatures above about 40.degree. C. followed by cooling to recover the precipitate.

Abstract: A low-temperature sinterable ceramic composition comprising 1 to 20% by weight of Al.sub.2 O.sub.3, 15 to 50% by weight of SiO.sub.2, 0 to 5% by weight of MgO, 3 to 18% by weight of CaO, 0 to 5% by weight of TiO.sub.2, 1 to 8% by weight of B.sub.2 O.sub.3, 0 to 2% by weight of Li.sub.2 O, 20 to 80% by weight of at least one of zircon, mullite and spinnel, and 1 to 12% by weight of a fluoride selected from CaF.sub.2, MgF.sub.2, LiF, AlF.sub.3, MnF.sub.2, BaF.sub.2 and SrF.sub.2.

Abstract: The invention relates to a refractory brick on the basis of sintered magnesium oxide and MgO.Al.sub.2 O.sub.3 spinel and possibly up to three percent by weight of customary impurities. Such customary impurities are primarily CaO, Fe.sub.2 O.sub.3 and SiO.sub.2, which are included as impurities in the MgO used in the production of the spinel. The refractory brick according to the invention is characterized by the fact that it has a refractoriness under load of more than 1740.degree. C. and a compression settling of -3 to -5% at 1400.degree. C. after 24 hours under a load of 0.2N/mm.sup.2. The refractory brick according to the invention exhibits the advantage that as a result of the combination of its characteristics of gas permeability, pore volume, refractoriness under load and compression settling, it is particularly well suited for use in rotary hearth furnaces for the cement industry.

Abstract: Novel preheatable molded refractory insulating liners and methods of use thereof for lining metallurgical vessels, such as hot tops, ladels, tundishes, troughs and pipes, etc., which serve to transfer molten metals, such as ferrous alloys, are disclosed. The new and vastly improved preheatable liners are suitable for developing effectively the required hot strength needed for casting molten metals at vessel preheat temperatures and casting temperatures. The unique preheatable liners additionally possess the needed hot strength during the range of casting temperatures as are experienced in the metal making industry.

Abstract: A cofired structure comprised of a refractory metal metallization supported by a substrate free of large voids is produced by forming a liquid phase sinterable ceramic composition containing SiO.sub.2 in some form and a sulfate of an alkali metal and/or an alkaline earth metal, admixing the composition with an organic binding medium, shaping the mixture into a thin sheet, contacting the sheet with refractory metal metallization material, and cofiring the resulting structure whereby the free carbon produced by pyrolysis of the organic medium is removed by reaction with the sulfate before closed porosity is initiated.

Abstract: There is disclosed a unique substantially non-reactive refractory material suitable for use as a material of construction for various component parts of an electrolytic light metal, particularly magnesium, production cell. The non-reactive refractory material is comprised of a magnesium aluminum spinel. When used in block form the blocks may be joined together by use of a phosphate-spinel mortar.

Abstract: Ceramic shaped articles are disclosed which are formed of dense, non-metallic, mechanically resistant materials and contain eutectic constituents consisting of zirconium oxide, hafnium oxide and at least one other high-melting oxide and mixtures thereof. The composition exhibits excellent hardness, wear properties and bending strength. A method for preparing the articles is also disclosed wherein the appropriate mixture in a hypoeutectic, eutectic, or hypereutectic ratio is heated to its melting point, poured into a preheated mold and cooled.

Abstract: A ceramic material for a honeycomb structure is prepared from a mixture of raw materials comprising per 100 parts by weight of the mixture 40 to 90 parts by weight of cordierite powder and 10 to 60 parts by weight of crystalline glass powder having a crystalline phase consisting mainly of a solid solution of .beta.-spodumene. The mixture consists essentially of 51.5 to 64.4% by weight of siO.sub.2, 24.8 to 33.7% by weight of Al.sub.2 O.sub.3, 5.5 to 12.4% by weight of MgO and 0.4 to 2.7% by weight of Li.sub.2 O. It may further contain up to 5.1% by weight of TiO.sub.2 and up to 1.8% by weight of ZrO.sub.2.

Abstract: A zirconia type sintered body consisting essentially of 50 to 98% by weight of zirconia (ZrO.sub.2) containing 1.5 to 5 mole % of yttria (Y.sub.2 O.sub.3) and 50 to 2% by weight of alumina (Al.sub.2 O.sub.3), spinal (MgAl.sub.2 O.sub.4) or mullite (3Al.sub.2 O.sub.3.2SiO.sub.2), and having a three-point bending strength of at least 1700 MPa is provided. This sintered body is prepared by a process wherein a powdery composition consisting essentially of 50 to 98% by weight of (a1) a powder of zirconia containing 1.5 to 5 mole % of yttria or (a2) a mixture comprising 1.5 to 5 mole % of a yttria powder and 95 to 98.5 mole % of a zirconia powder and 2 to 50% by weight of (b) a powder of an alumina type oxide selected from alumina, an alumina-magnesia type oxide, an alumina-silica type oxide, a mixture of alumina and magnesia and a mixture of alumina and silica is subjected to a hot isotactic pressing treatment under a pressure of at lesast 50 MPa at temperature of 1300.degree. C. to 1700.degree. C.

Abstract: The disclosed polycrystalline transparent sintered body contains Al.sub.2 O.sub.3 and MgO at a molar ratio of (0.54:0.46) to (0.58:0.42) and has in-line transmittance of more than 77% for 1 mm thickness at a light wavelength of 0.6 .mu.m, which sintered body is produced by preparing fine spinel powder through hydrolysis of an isopropanol solution of aluminum isopropoxide and magnesium isopropoxide, forming a shaped body from the powder, and sintering the shaped body.

Abstract: Novel aqueous inorganic particle slurries, wherein some of the particles have had their charge potential altered to a sufficient extent to prevent segregation or settling of the particles, are described, along with a method for their preparation. The method of forming slurries of negatively charged particles comprises treating some of the particles with a cationic agent to reduce their charge and mixing these treated particles with the remainder of the particles to form a thick, cream-like flowable composition of a thixotropic nature. When slurries of positively charged particles are to be formed, an anionic agent is used instead of a cationic agent.

Abstract: The disclosed polycrystalline transparent sintered body contains Al.sub.2 O.sub.3 and MgO at a molar ratio of (0.54:0.46) to (0.58:0.42) and has an in-line transmittance of more than 77% for 1 mm thickness at a light wavelength of 0.6 .mu.m, which sintered body is produced by preparing fine spinel powder through hydrolysis of an isopropanol solution of aluminum isopropoxide and magnesium isopropoxide, forming a shaped body from the powder, and sintering the shaped body.

Abstract: Spinel fine powders having high purity suitable for raw materials for producing a dense and uniform spinel sintered body, are produced by hydrolyzing an alcohol solution of specifically defined magnesium alkoxides and aluminum alkoxides in a specific mixing ratio.

Abstract: This invention relates to a method for producing nitride bonded refractory shapes in which the bonding matrix is formed in situ. The method comprises forming a batch including a coarser portion selected from the group calcined and fused aggregates of alumina, aluminosilicate, and magnesium aluminate spinel and a finer portion consisting essentially of finely divided silicon metal and alumina as well as fines of the above mentioned refractory aggregate needed to achieve the desired screen analysis. The silicon metal and alumina react in the nitriding atmosphere to form a low porosity matrix generally comprising silicon oxynitride with corundum distributed therethrough.

Abstract: A refractory composition for use in contact with molten aluminum alloys containing a refractory aggregate, a binder and 9Al.sub.2 O.sub.3.2B.sub.2 O.sub.3. The aluminum borate may be of the type produced as a by-product in the production of ferro-boron alloys and known as aluminum boron slag.

Abstract: Vibratable, monolithic refractory mixes useful to form linings for receptacles and related apparatus components used to handle or treat molten metal, such as ladles, tundishes, troughs and runners, including novel binders therefor.

Abstract: An improved process for the production of alkaline earth, aluminum-containing spinel compositions, preferably magnesium, aluminum-containing spinel compositions and preferably further comprising at least one additional metal component, comprises combining at least one alkaline earth metal component; at least one organic compound having inherent basicity, and at least one aluminum component at selected pH conditions to form a precipitate and calcining the precipitate to form a spinel composition. The product spinel composition, prepared in the presence of such an organic template and preferably with included additional metal components, is particularly suited for use to reduce the amount of sulfur oxides emitted from a catalyst regeneration zone, e.g., a catalytic cracking unit regeneration zone.

Abstract: An improved process for the production of alkaline earth, aluminum-containing spinel compositions, preferably magnesium, aluminum-containing spinel compositions and preferably further comprising at least one additional metal component, comprises combining at least one alkaline earth metal component; at least one solid organic material acting to alter at least one property of the spinel composition and being capable of being at least partially combusted during the calcination step described hereinafter, and at least one aluminum component at selected pH conditions to form a precipitate and calcining the precipitate to form a spinel composition. The product spinel composition, prepared in the presence of a solid organic material and preferably with included additional metal components, is particularly suited for use to reduce the amount of sulfur oxides emitted from a catalyst regeneration zone, e.g., a catalytic cracking unit regeneration zone.

Abstract: A method for producing a cordierite body having no anisotropic property in coefficient of thermal expansion comprises the steps of preparing a raw material containing kaolin mineral and talc as main ingredients, and preformed cordierite particles formed from the raw material, mixing and kneading the raw material together with the preformed cordierite particles into a slurry, forming the slurry into a formed body and firing the formed body.

Abstract: A means for producing nitride bonded refractory shapes, in situ, by mixing an aluminum metal powder, relatively pure silica, crude clay and a refractory aggregate. The mixes are pressed into shapes and burned at elevated temperatures in a nitriding atmosphere to form the bond.

Abstract: A composition comprised ofI. 60 to 90% wt. of(a) from 70 to 95 weight percent of at least one of(i) one or more MgAl.sub.2 O.sub.4 spinels heated at a temperature of about 600.degree. C. to about 1700.degree. C. and having less than 20% by weight of segregated phases of Al.sub.2 O.sub.3 or MgO;(ii) MgAl(OH).sub.5-ny X.sub.y.sup.n where y.ltoreq.1; x=OH.sup.-, halogen, SO.sub.4.sup.=, NO.sub.3.sup.- carboxylate, halogenated carboxylate, H.sub.2 PO.sub.4.sup.-, HPO.sub.4.sup.=, HCO.sub.3.sup.-, and the like which is prepared by coprecipitating a Mg and Al salt under controlled pH and Mg/Al ratios and which may also include segregated phases of AlO(OH), Mg(OH).sub.2 and/or Al(OH).sub.3 following pH adjustment;(iii) intermediates of (1) and (2) prepared by partial calcination of (2) at temperatures .gtoreq.300.degree. C. but .ltoreq.600.degree. C.

Abstract: A spinel containing slip-casting composition, method for preparing the spinel slip-casting composition and method for casting the slip into usable forms are described. The spinel employed to prepare the castable slips is a pre-calcined spinel and a calcined spinel each prepared in the manner of copending application Ser. No. 184,189, filed Sept. 4, 1980, which is ball-milled with water, then mixed with a deflocculant at pH 9 or below. The slurry or "slip" is cast into a mold porous to water until the desired thickness of solid has been obtained and the excess "slip" decanted or otherwise withdrawn from the mold. The green shape is retained in the mold until it gains green strength, 1 hour to 5 days, and thereafter placed in an oven wherein it is fired to above about 1400.degree. C. for from 1 to 20 hours until it has reached its maximum density of between about 50 and 99 percent of theoretical.

Abstract: Several methods are set forth for preparing polymetallic spinels by coprecipitating two or more metal compounds in a proportion to provide a total of eight positive valences when combined in the oxide form in the spinel crystal lattice. The methods disclosed require coprecipitation of the metals in the hydroxide form or convertible to the hydroxide-oxide form, calcining the coprecipitate, and finally sintering the calcined material at about one-half its melting point or greater, thereby forming a spinel which has a density of greater than 50 percent of the theoretical density of spinel crystal. Also disclosed are techniques for preparing spinels having more than two metals incorporated into the spinel lattice, as well as a separate oxide phase associated with the spinel crystallites, and slipcasting compositions.

Abstract: A spinel containing slip-casting composition, a method for preparing the spinel slip-casting composition and a method for casting the slip into usable forms are described. The spinel employed to prepare the castable slips is a pre-calcined spinel prepared in the manner of copending application Ser. No. 184,189, filed Sept. 4, 1980, which is ball-milled with water, then mixed with a deflocculant at pH 9 or below and optionally with a molding aid. The slurry or "slip" is cast into a mold porous to water until the desired thickness of solid has been obtained and the excess "slip" decanted or otherwise withdrawn from the mold i.e., drain cast method or the "slip" is solid cast and dried to produce a green solid casting. The green shape is retained in the mold until it gains green strength, 1 hour to 5 days, and thereafter placed in an oven wherein it is fired to above about 1400.degree. C. for from 1 to 20 hours until it has reached its maximum density of between about 55 and 99 percent of theoretical.

Abstract: A basic brick composition containing spinel clinker and magnesia clinker wherein pulverized iron oxide by additional weight mixing ratio is mixed or special magnesia clinker is substituted for magnesia clinker instead of addition of iron oxide.

Abstract: This invention is a new process for producing refractory crystalline oxides having improved or unusual properties. The process comprises the steps of forming a doped-metal crystal of the oxide; exposing the doped crystal in a bomb to a reducing atmosphere at superatmospheric pressure and a temperature effecting precipitation of the dopant metal in the crystal lattice of the oxide but insufficient to effect net diffusion of the metal out of the lattice; and then cooling the crystal. Preferably, the cooling step is effected by quenching. The process forms colloidal precipitates of the metal in the oxide lattice. The process may be used, for example, to produce thermally stable black MgO crystalline bodies containing magnetic colloidal precipitates consisting of about 99% Ni. The Ni-containing bodies are solar-selective absorbers, having a room-temperature absorptivity of about 0.96 over virtually all of the solar-energy spectrum and exhibiting an absorption edge in the region of 2 .mu.m.

Abstract: A spinel type dense fused refractory product having excellent corrosion resistance comprises a crystalline structure consisting essentially of more than 50% by weight of composite spinel phase comprising RO component selected from MgO and FeO and R'.sub.2 O.sub.3 component selected from Cr.sub.2 O.sub.3, Al.sub.2 O.sub.3 and Fe.sub.2 O.sub.3 and periclase phase and a small content of glass matrix phase which consists essentially of the following constituents, analytically on a weight basis; a ratio of Cr.sub.2 O.sub.3 to Al.sub.2 O.sub.3 of 3.5 to 5.5; and 20% to 40% of MgO; 1.5% or less of CaO; 15% or less of Fe.sub.2 O.sub.3 (FeO is also calculated for Fe.sub.2 O.sub.3) and 5% or less of SiO.sub.2.

Abstract: The invention provides a particulate sealing material for use in preparing hermetic seals between ceramic and cermet members, which material comprises at least 70 wt. % refractory oxide and minor quantities of non-vitreous additive comprising SiO.sub.2, MgO and B.sub.2 O.sub.3. This particulate sealing material is conveniently pressed into the form of a coherent element shaped to suit the particular sealing operation concerned, e.g. the sealing of an open end of a ceramic arc tube to a cermet closure therefor. The invention also provides a method of sealing a ceramic component to a cermet member by interposing said sealing material between the opposed faces of the component and member and applying heat and pressure to sinter the sealing material and achieve a seal between the component and member.

Abstract: The invention relates to low-expansion ceramics, the chemical composition of which consists of 1.2 to 20% by weight of magnesia (MgO), 6.5 to 68% by weight of alumina (Al.sub.2 O.sub.3), 19 to 80% by weight of titanium in terms of titanium oxide (TiO.sub.2), 1 to 20% by weight of silica (SiO.sub.2), and 0.5 to 20% by weight of iron in terms of ferric oxide (Fe.sub.2 O.sub.3); the major component of crystalline phase thereof is a solid solution of magnesium oxide-aluminum oxide-titanium dioxide-silicon oxide-iron oxide; the ceramics have a coefficient of thermal expansion of not more than 20.times.10.sup.-7 (1/.degree.C.) in a temperature range of 25.degree. C. to 800.degree. C., a four-point flexural strength of not smaller than 50 kg/cm.sup.2 at room temperature, and a melting point of not lower than 1,500.degree. C.

Abstract: The present invention relates to low-expansion ceramics having a chemical composition of the ceramics essentially consisting of 2 to 20% by weight of magnesia (MgO), 10 to 68% by weight of alumina (Al.sub.2 O.sub.3), and 30 to 80% by weight of titanium in terms of titanium oxide (TiO.sub.2), wherein the major component of crystalline phase thereof is magnesium-alumium-titanate phase, and the ceramics have a coefficient of thermal expansion of not more than 20.times.10.sup.-7 (1/.degree.C.) in a temperature range of 25.degree. C. to 800.degree. C. and a melting point of not lower than 1,500.degree. C., wherein the magnesium-alumium-titanate phase as the major component of the crystalline phase thereof is given by a chemical formula Mg.sub.10x Al.sub.8y Ti.sub.5(1-x-y) O.sub.(10+2y), here 0.02.ltoreq.x.ltoreq.0.20, 0.10.ltoreq.y.ltoreq.0.68, and 0.20.ltoreq.(x+y).ltoreq.0.

Abstract: Cordierite ceramic honeycomb consisting mainly of cordierite in crystal phase and containing not more than 20% by weight of at least one crystal selected from the group consisting of spinel, mullite and corundum and having a thermal expansion coefficient at a temperature range of 25.degree.-1,000.degree. C. being less than 22.times.10.sup.-7 (1/.degree.C.).