Abstract: This invention relates to highly toughened alumina sintered bodies, and the highly toughened alumina sintered bodies are fabricated by sintering an &agr;-aluminum oxide powder which is obtained by employing an aluminum hydroxide produced by the Bayer's process as a starting material, and calcining at 900-1200° C. a mixture obtained by adding abrasion powder worn from pulverizing alumina balls or another product to the material, in an amount of 0.01-20 mass % as seed crystals for &agr;-aluminum oxide.

Abstract: An inexpensive high-performance cutting or grinding oil capable of significantly improving the cutting efficiency. Into a liquid component of the cutting or grinding oil are dispersed fine powders of boron nitride of hexagonal system and/or crystal line turbostratic structure, particularly crystalline turbostratic structure, having a mean particle size of primary particles not larger than 1 .mu.m.

Abstract: The present invention relates to a method for producing a porous silicon nitride sintered body having high strength and low thermal conductivity, which comprises of adding more than 10 volume % of rodlike beta-silicon nitride single crystals with a larger mean diameter than that of a silicon nitride raw powder into a mixture comprising the silicon nitride raw powder and a sintering additive, preparing a formed body with rodlike beta-silicon nitride single crystals oriented parallel to the casting plane according to a forming technique such as sheet casting and extrusion forming, sintering said formed body to develop elongated silicon nitride grains from the added rodlike beta-silicon nitride single crystals as nuclei and obtain the sintered body with the elongated grains being dispersed in a complicated state.

Abstract: An object of the present invention is to provide a high-porosity, high-strength porous silicon nitride having great tolerance with respect to strain and stress, and a method for producing the same, and the present invention relates to a high-porosity, high-strength porous silicon nitride having great tolerance with respect to strain and stress, characterized in that rodlike grains of silicon nitride with a minor diameter of 0.5 to 10 .mu.m and an aspect ratio of 10 to 100 are oriented in a single direction, and the rest of the structure other than the rodlike grains consists solely of pores with a porosity of 5 to 30%, and further the above-mentioned porous silicon nitride is produced by mixing rodlike particles of silicon nitride with a minor diameter of 0.5 to 10 .mu.

Abstract: The present invention provides silicon nitride ceramics having high thermal conductivity and a method for production thereof. This invention relates to a method for producing a silicon nitride sintered body having a microstructure with silicon nitride crystals oriented uniaxially and exhibiting high thermal conductivity of 100 to 150 W/mK in the direction parallel to the orientation direction of the crystals, which comprises of preparing a slurry by mixing a mixed powder of a sintering auxiliary, beta-silicon nitride single crystals as seed crystals and a silicon nitride raw powder with a dispersing medium, forming the slurry by tape casting or extrusion forming, calcining the formed silicon nitride body with beta-silicon nitride single crystals oriented parallel to the casting plane to remove the organic components, densifying it by hot pressing and the like if required, and further annealing it at 1700 to 2000.degree. C. under the nitrogen pressure of 1 to 100 atmospheres.

Abstract: The present invention relates to a silicon nitride sintered body having a remarkably increased strain-to-fracture, a low elasticity and high strength, characterized by consisting of a layered structure of alternating porous silicon nitride layers 1 to 1000 .mu.m thick with a porosity of 5 to 70 volume % and dense silicon nitride layers 1 to 1000 .mu.m thick with a porosity of less than 5 volume %, being layered as materials with optional tiers. In addition, this invention relates to a method for producing the silicon nitride sintered body as described above, which comprises of forming dense layers and porous layers by sheet casting or extrusion forming so as to prepare the layers to be capable of 1 to 1000 .mu.m thick after sintering, stacking them to obtain layered materials with optional tiers and sintering them at 1600.degree. to 2100 .degree. C. under a nitrogen atmosphere.

Abstract: The present invention provides a method for producing an aluminum nitride sintered body having excellent characteristics and an aluminum nitride powder conveniently and inexpensively. The present invention relates to a method for production of an aluminum nitride sintered body comprising forming a metal aluminum power into a thin-plate like shape, heating the formed body to a temperature not exceeding the melting point of aluminum in a vacuum atmosphere, and then sintering it under N.sub.2 pressure (1-150 kg/cm.sup.2), and a method for production of an aluminum nitride powder comprising heating a metal aluminum powder to a temperature not exceeding the melting point of aluminum in a vacuum atmosphere, sintering it under N.sub.2 pressure (1-150 kg/cm.sup.2, and further cooling and pulverizing it.

Abstract: A method for the production of a composite consisting of cellulose fibers coated with a calcium phosphate compound consists essentially of phosphorylating the surface of cellulose fibers, immersing the surface-phosphorylated cellulose fibers in an aqueous solution containing calcium ions and hydroxyl ions, removing the cellulose fibers from the aqueous solution and subsequently immersing them in an aqueous solution containing calcium ions and phosphoric acid ions, and then removing the cellulose fibers from the aqueous solution. Also disclosed is a composite produced by the method.

Abstract: A plasminogen activator such as urokinase or tissue plasminogen activator is covalently bonded to a porous body composed of calcium phosphate to form a plasminogen activator-porous body complex. The tricalcium phosphate can be .alpha.-tricalcium phosphate, .beta.-tricalcium phosphate, hydroxyapatite, tetracalcium phosphate, octacalcium phosphate and mixtures thereof. In a preferred embodiment, .beta.-tricalcium phosphate which has excellent biocompatibility with the body or a mixture of .beta.-tricalcium phosphate and hydroxyapatite is used. Preferably, synthetic calcium phosphate is used is to avoid impurities contained by natural calcium phosphate. Covalent bonding is by crosslinking with glutaraldehyde, bismaleimides, dihalogenic aryls or diisocyanates, or by using cyanogen bromide, diazotization or periodic acid. The complex can be filled into a column to form a bioreactor.

Abstract: A platelike hydroxyapatite is produced by preparing from a phosphate and a calcium salt an aqueous slurry of amorphous calcium phosphate having an atomic ratio of calcium atoms to phosphorus atoms in the range of 1.3:1 to 2.0:1, adding to the aqueous slurry not less than 10% by weight of alcohol based on the amount of the aqueous slurry, and subjecting the resultant mixture to a hydrothermal treatment.

Abstract: Powdery calcium carbonate and a powdery dihydrate of calcium monohydrogenohosphate are weighed to get a Ca/P ratio of 1.45 to 1.67. The powdery mixture thus prepared is then added pure water at a temperature of 30.degree. C. or higher to obtain an aqueous slurry having a concentration of about 10% by weight. Thereafter, the aqueous slurry is subjected to a rotational attrition by using a ball mill to conduct a mechanochemical reaction of the calcium carbonate with the dihydrate of calcium monohydrogenphosphate. The slurry is then dried completely at 80.degree. C., followed by pulverization to yield a dry powder of calcium phosphate hydrate. The dry powder is calcinated at a temperature ranging from 720.degree. to 1,150.degree. C. for 1-10 hours or more to give calcium phosphate powder, which is molded in a desired shape and is sintered at a certain temperature to obtain a sintered body of calcium phosphate.

Abstract: A fibrinolytic enzyme such as urokinase, tissue plasminogen activator or streptokinase is covalently bounded to a bioadaptable porous crystalline glass to produce a thrombolytic material. Production of the glass involves combining 40-50 mol% calcium oxide, 20-30 mol% titanium dioxide and 25-35 mol% diphosphorous pentoxide to form a mixture, and combining the mixture with 0.5-4.0 mol% disodium oxide. A bioreactor for converting plasminogen in blood into plasmin can be prepared by packing the material in a column. When finely comminuted, the material can be administered into the blood of a patient for removing blood clots.

Abstract: A powder for coating the surface of a titanium metal is obtained by mixing compounds as raw materials for CaO, TiO.sub.2, and P.sub.2 O.sub.5 with a small amount of a Na.sub.2 O-containing compound, fusing the resultant mixture, and solidifying and pulverizing the fused mixture. A coating of a calcium phosphate compound adhering with great fastness to the surface of the titanium metal is formed by preparing an aqueous slurry containing the powder mentioned above, applying the aqueous slurry to the surface of the titanium metal, and heat-treating the coated titanium metal.

Abstract: A dense coating of a calcium phosphate compound is formed on the surface of a bioadaptable ceramic substrate by applying to the ceramic calcium metaphosphate alone or a mixture of calcium metaphosphate with calcium pyrophosphate, heat-treating the applied layer thereby fusing the applied layer to the surface of the ceramic, then applying to the fused layer a slurry resulting from the mixture of calcium metaphosphate with tetracalcium phosphate, and subsequently heat-treating the applied layer of the slurry thereby inducing reaction of the slurry.

Abstract: A composition produced as a result of mixing alumina, silica, and a calcium phosphate compound in a specific ratio exhibits high affinity for bioceramics. When a bioceramic is coated with this composition and the coated bioceramic is heated, the composite is fused fast with the bioceramic to produce a composition bioceramic which is active to vital tissues.

Abstract: Sintered article suitable for artificial bones, for example, containing a calcium phosphate compound as a main component and additionally containing spinel or magnesium oxide formed by sintering magnesium oxalate dihydrate. This sintered article is produced by adding alumina and silica or magnesium oxalate dihydrate to a calcium phosphate compound and firing the resultant mixture.

Abstract: A method of forming a rigid film of calcium phosphate compound having good bio-conformance on a surface of a ceramic or metal substrate is disclosed. According to this method, a slurry of a fine powder of phosphate-series glass of CaO-Na.sub.2 O-P.sub.2 O.sub.5 -Al.sub.2 O.sub.3 is applied to the surface of the substrate and is dried and heat-treated to form a binder layer which covers the surface of the substrate. A peptisation agent such as ammonium polyacrylate and water are mixed with a fine powder of a calcium phosphate compound having a particle size of 1 .mu.m or less to prepare a slurry, and this slurry is applied to the surface of the binder layer. The slurry on the binder layer is dried and heat-treated to form a film of the calcium phosphate compound. The film of the calcium phosphate compound formed by this method is uniform and has high adhesion strength with the substrate.

Abstract: Porous spheres of calcium phosphate compound are produced by preparing an aqueous solution containing a water-soluble calcium salt, a calcium ion complexing agent, and a water-soluble phosphate, adjusting the pH of the aqueous solution, adding hydrogen peroxide to the aqueous solution, and heating the resultant mixture.

Abstract: A microfine .beta.-tricalcium phosphate powder is produced by mixing hydrogen calcium phosphate powder, calcium carbonate powder, and water in amounts calculated to give a slurry having a solids concentration in the range of 5 to 15% by weight and a CA:P atomic ratio in the range of 1:1.4.about.1.6 and subjecting the slurry to attrition.