Sumitomo Chemical Company, Limited

Shinji Fujiwara

Kunio Saegusa

Takeshi Hattori

Akira Hasegawa

Hiroshi Tabuchi

Kenji Saita

Hirotaka Ozaki

Masahide Mohri

Akihiko Takahashi

Noriaki Fujita

Norifumi Azuma

A method for producing an &#x3b1; alumina sintered body for the production of a sapphire single crystal characterized in that a relative density is 60% or more, a closed porosity is 10% or less, a purity is 99.99% by mass or more, each content of Si, Na, Ca, Fe, Cu and Mg is 10 ppm or less, and a volume is 1 cmor more, and the &#x3b1; alumina sintered body can be obtained by mixing 100 parts by weight of an &#x3b1; alumina with 1 part by weight or more and 20 parts by weight or less of an &#x3b1; alumina precursor to obtain a mixture, forming a compact from the obtained mixture, and firing the obtained compact.

&#x3b1; alumina sintered body for production of sapphire single crystal

An object of the present invention is to provide &#x3b1; alumina for the production of a sapphire single crystal, capable of producing a sapphire single crystal with high production efficiency; and a method for producing the same. Disclosed are &#x3b1; alumina for the production of a sapphire single crystal, including 100 parts by weight of &#x3b1; alumina (I) and 25 to 235 parts by weight of &#x3b1; alumina (II), wherein the &#x3b1; alumina (I) has a specific surface area of 0.1 to 5 m/g and a bulk density of 1.5 g/cmor more, the &#x3b1; alumina (II) is composed of sintered particles and also has a specific surface area of 1 m/g or less and a relative density of 85% or more, and each of the body particles has a volume of 0.01 cmor more; and a method for producing the same.

Alpha alumina for the production of sapphire single crystal and method for producing the same

&#x3b1;-Alumina powder having a purity of at least 99.99% by weight, a specific surface area of from 0.1 to 2.0 m/g, a relative density of from 55 to 90%, and a closed porosity of 4% or less, wherein in a weight-based particle size distribution obtained by the dry sieving test according to JIS K0069 (1992), an amount of particles having a particle size of less than 75 &#x3bc;m is 5% by weight or less; an amount of particles having a particle size exceeding 2.8 mm is 15% by weight or less; and at least one frequency maximum peak appears in a particle size range of 100 &#x3bc;m or more and to less than 850 &#x3bc;m. This &#x3b1;-alumina powder can be charged in a crucible at a high bulk density, from which sapphire having a few voids can be produced without causing the oxidation of a crucible in a heat melting step.

Alpha-alumina powder

There is provided a process for the preparation of a alumina precursor powder from aluminum hydroxide powder obtained by hydrolysis of aluminum alkoxide which precursor enables to provide alumina powder with a high volumetric efficiency. Such process comprises mixing aluminum hydroxide powder obtained by hydrolysis of an aluminum alkoxide with the following aqueous medium so as to obtain an aluminum hydroxide mixed slurry and then drying the aluminum hydroxide mixed slurry: aqueous medium: water or a medium mixture of water and a water-soluble alcohol wherein a water content in said medium mixture is not less than 15 parts by weight to 100 parts by weight of the medium mixture.

Process for preparation of alumina powder and precursor thereof

A method of producing an Indium Tin Oxide powder is described. A method of producing an Indium Tin Oxide powder comprising the steps of: (1) mixing a raw aqueous solution containing indium ions and tin ions and having a proportion of divalent tin ions in the tin ions of 50 wt % or more with an alkali aqueous solution, (2) separating the product into solid and liquid, and (3) calcinating the resulted solid.

Method of producing Indium Tin Oxide powder

A method for producing an indium-containing aqueous solution having a reduced amount of metal impurities is provided. A method for producing an indium-containing aqueous solution having a reduced amount of metal impurities which comprises bringing an aqueous solution containing indium and metal impurities whose hydrogen ion concentration is adjusted at 0.5 mol/L to 3 mol/L into contact with a non-chelate ion-exchange resin to remove the metal impurities, and a method for producing an indium-containing aqueous solution having a reduced amount of metal impurities which comprises bringing an aqueous solution containing indium and metal impurities into contact with a chelate ion-exchange resin to remove the metal impurities are provided.

Methods for producing indium-containing aqueous solutions containing reduced amounts of metal impurities

Method for producing high density indium-tin-oxide sintered body

A powdery .alpha.-alumina having an alumina purity of at least 99.8 wt. %, a sodium content of 40 ppm or less and an iron content of 20 ppm or less, which is obtained by grinding aluminum hydroxide which is produced by the Bayer process or a transition alumina which is obtained by precalcining aluminum hydroxide produced by the Bayer process, and calcining the aluminum hydroxide or transition alumina in an atmosphere containing 1 vol. % or more of a hydrogen chloride gas, or an atmosphere containing 1 vol. % or more of a chlorine gas and 0.1 vol. % or more of steam, at a temperature of 600 to 1400.degree. C.

Alpha-alumina and method for producing same

A method for producing an indium oxide-tin oxide powder, which comprises supplying to react an aqueous solution of an indium salt, an aqueous solution of a tin salt and an aqueous alkaline solution into water at 40.degree. C. or more and less than 100.degree. C. so that the pH during the reaction is maintained within the range from 4 to 6, forming a precipitate, washing the formed precipitate after solid-liquid separation, and calcining the precipitate at 600.degree. C. or more and 1300.degree. C. or less.

Indium oxide-tin oxide powders and method for producing the same

A process of producing a powder of a transition-metal boride includes producing metal boride particles in a molten metal by contacting a molten salt, to which at least one boron compound was added, with the molten metal containing a transition-metallic element selected from the Groups IV and V of the Periodic Table at an atomic ratio of elemental boron to transition-metallic element from 0.5 to 4.0, while maintaining a contact temperature which is not lower than the melting point of the molten metal and which is less than 1000.degree. C., and recovering the particles from the molten metal. According to the present invention, fine powders of the transition-metal boride which contain few agglomerated particles may be easily obtained using relatively inexpensive feed materials, such as the boron oxides, at a low temperature less than 1000.degree. C. without the necessity of a grinding step.

Process for producing powders of transition metal boride

A method for forming a hydroxyapatite coating film on a substrate which comprises coating a dispersion of flocculated colloids of hydroxyapatite on a substrate and drying. The coating method of this invention does not require heating of the coated substrate to high temperature and hence can also be applied to a substrate which is easily deteriorated with heat. The coated substrate of this invention has excellent strength and adhesion force and is useful in a variety of fields, particularly as an implant and as a material, adsorbing and separating agent.

Method for forming hydroxyapatite coating film

A method for forming a hydroxyapatite coating film on a surface of a substrate which comprises coating a coating liquor onto a surface of a substrate, followed by drying and then subjecting to insolubilization (e.g., treating with an insolubilizing agent or calcination) which is characterized by using a coating liquor comprising a colloidal dispersion of hydroxyapatite having a fine particle size of 0.5 .mu.m or less.

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Tsukuba, Japan

Shinji Fujiwara