Abstract: A production method comprising the steps of: spraying an aluminum hydroxide powder having a specific surface area measured by a nitrogen adsorption method of 0.3 m2/g or more and 3 m2/g or less; a ratio of an average particle diameter D50, which is a particle diameter at which 50% by weight of particles from the finest particle side are accumulated in a particle diameter distribution measured by a laser diffraction scattering method, to a sphere conversion particle diameter Dbet calculated from a specific surface area, of 10 or less; and the average particle diameter D50 of 2 ?m or more and 100 ?m or less, into flames, and then collecting it in the form of a powder to give a spherical alumina powder having a small specific surface area and a low uranium content, and capable of providing high thermal conductivity to resin compositions.

Abstract: A production method comprising the steps of: spraying an aluminum hydroxide powder having a specific surface area measured by a nitrogen adsorption method of 0.3 m2/g or more and 3 m2/g or less; a ratio of an average particle diameter D50, which is a particle diameter at which 50% by weight of particles from the finest particle side are accumulated in a particle diameter distribution measured by a laser diffraction scattering method, to a sphere conversion particle diameter Dbet calculated from a specific surface area, of 10 or less; and the average particle diameter D50 of 2 ?m or more and 100 ?m or less, into flames, and then collecting it in the form of a powder to give a spherical alumina powder having a small specific surface area and a low uranium content, and capable of providing high thermal conductivity to resin compositions.

Abstract: The present invention relates to a ceramic plate material for side dams of a twin-drum strip caster, the ceramic plate material containing Al of 9 mass % or more in terms of Al equivalent and having the properties of; bending strength at room temperature of not less than 120 MPa, bending strength at 1,000° C. of not less than 65 MPa, hardness (Hv) of 50 to 350, fracture toughness KIC at 1,000° C. of not less than 1 MPa·m1/2, thermal conductivity in the temperature range from room temperature to 1,000° C. of not more than 8 W/(m·K), thermal shock resistance index R? of not less than 800 W/m, and wettability with molten steel (contact angle ?) of not less than 120°: and allows molten stainless steel to be continuously cast for a long period of time.

Abstract: The present invention provides a method for producing a grain-oriented silicon steel sheet not having inorganic mineral films by using an annealing separator capable of preventing the inorganic mineral films composed of forsterite (Mg2SiO4), and so on, from forming during final annealing, comprising the steps of decarburization annealing followed by coating of annealing separator and final annealing, wherein alumina powder calcined at a calcination temperature of 900 to 1,400° C., or further having a BET specific surface area of 1 to 100 m2/g, an oil absorption of 1 to 70 ml/100 g, and/or having a gamma ratio of 0.001 to 2.0, is used as the annealing separator. Magnesia having a BET specific surface area of 0.5 to 5 m2/g may be added to said alumina powder.

Abstract: The present invention provides a method for producing a grain-oriented silicon steel sheet not having inorganic mineral films by using an annealing separator capable of preventing the inorganic mineral films composed of forsterite (Mg2SiO4), and so on, from forming during final annealing, comprising the steps of decarburization annealing followed by coating of annealing separator and final annealing, wherein alumina powder calcined at a calcination temperature of 900 to 1,400° C., or further having a BET specific surface area of 1 to 100 m2/g, an oil absorption of 1 to 70 ml/100 g, and/or having a gamma ratio of 0.001 to 2.0, is used as the annealing separator. Magnesia having a BET specific surface area of 0.5 to 5 m2/g may be added to said alumina powder.

Abstract: The present invention relates to a ceramic plate material for side dams of a twin-drum strip caster, the ceramic plate material containing Al of 9 mass % or more in terms of Al equivalent and having the properties of; bending strength at room temperature of not less than 120 MPa, bending strength at 1,000° C. of not less than 65 MPa, hardness (Hv) of 50 to 350, fracture toughness KIC at 1,000° C. of not less than 1 MPa·m1/2, thermal conductivity in the temperature range from room temperature to 1,000° C. of not more than 8 W/(m·K), thermal shock resistance index R′ of not less than 800 W/m, and wettability with molten steel (contact angle &thgr;) of not less than 120°: and allows molten stainless steel to be continuously cast for a long period of time.

Abstract: While an insufficient lubricating effect caused by lack of lubricant is prevented and also while contamination of molten metal and insertion of molten metal caused by excessive feed of lubricant are prevented, a lubricating effect can be provided and continuous casting can be conducted over a long period of time. Molten metal is poured into a molten metal pool formed by a pair of cooling drums and side dams. The thus poured molten metal is cooled and solidified on circumferential surfaces of the cooling drums, so that a strip can be produced. In the above continuous strip casting method, the side dam is composed in such a manner that a portion of the ceramic plate on the inlet side in the rotational direction of the cooling drum is chamfered, wherein the portion comes into contact with an end surface of the cooling drum.

Abstract: Disclosed is an oxide superconductor comprising an oxide of RE, Ba and Cu, which consists of a superconductor having a texture wherein the crystal directions of the 123 phase in the matrix are uniform, large angle grain boundaries having an directional difference larger than 20.degree. are not present and the 211 phase is finely dispersed, or an aggregate thereof, wherein the superconductor is formed into a plate or wire and the c-axis of the crystal of the formed body is uniform within .+-.30.degree. to the normal of the plate face of the formed body or in the range of from 60.degree. to 120.degree. to said normal. Also disclosed is a process for the preparation of an oxide superconductor as set forth above, which comprises inserting a formed body as mentioned above to a heating furnace and moving a region of a temperature at which grains are formed in the 123 phase of the matrix of the formed body, i.e., through a region having a temperature of from 1050.degree. to 910.degree. C.

Abstract: The present invention relates to an oxide superconductor comprising a composite oxide of RE , Ba and Cu, wherein the superconductor comprises a micro structure comprised of a monocrystalline REBa.sub.2 Cu.sub.3 O.sub.7-x phase (123 phase) and a RE.sub.2 BaCuO.sub.5 phase (211 phase) finely dispersed therein, the 123 phase being formed in a plurality of domains respectively for individual RE compositions and in the order of the 123 phase forming temperatures in respective layers.

Abstract: Disclosed is an oxide superconductor comprising an oxide of RE, Ba and Cu, which consists of a superconductor having a texture wherein the crystal directions of the 123 phase in the matrix are uniform, large angle grain boundaries having an directional difference larger than 20.degree. are not present and the 211 phase is finely dispersed, or an aggregate thereof, wherein the superconductor is formed into a plate or wire and the c-axis of the crystal of the formed body is uniform within .+-.30.degree. to the normal of the plate face of the formed body or in the range of from 60.degree. to 120.degree. to said normal. Also disclosed is a process for the preparation of an oxide superconductor as set forth above, which comprises inserting a formed body as mentioned above to a heating furnace and moving a region of a temperature at which grains are formed in the 123 phase of the matrix of the formed body, i.e., through a region having a temperature of from 1050.degree. to 910.degree. C.