Agency of Industrial Science and Technology

Ministry of International Trade & Industry

Takeo Iga

Michihide Machida

Hideyo Tabata

Kazuo Saitoh

Shyoichi Kume

Yoshitaka Kuwahara

Shuzo Kato

Shinji Tomura

Shogo Hatano

Yoshio Murase

Yuichi Isawa

Needlelike single crystal particles of .alpha.- alumina, .theta.-alumina, mullite, sillimanite, etc. are produced by adding a silicon-containing substance to needlelike alumina precursor particles and heating the resultant product of addition.

Method for production of needlelike crystalline particles

A high-strength sintered article of chemical substances having the .beta.-silicon nitride type crystal structure is produced by blending 50 to 99.9 weight percent of a .beta.-silicon nitride and/or .beta.'-Sialon and 50 to 0.1 weight percent of a mixture, as a sintering aid, consisting of BeO, Ga.sub.2 O.sub.3, and Al.sub.2 O.sub.3 in respective amounts such as to have a Ga.sub.2 O.sub.3 /BeO ratio in the range of from 2.8 to 9.4, an Al.sub.2 O.sub.3 /BeO ratio in the range of from 0.0 to 2.6, and an Al.sub.2 O.sub.3 /Ga.sub.2 O.sub.3 ratio in the range of from 0.0 to 1.1, all ratios being ratios by weight and sintering the resultant blend.

Method for manufacture of high-strength sintered article of substances

Aluminum carbonate hydroxide ammonium, a new compound, is produced by causing a solution of ammonium hydrogencarbonate to be reacted upon by a soluble aluminum salt. .alpha.-Alumina is obtained by thermal decomposition of this ammonium aluminum carbonate hydroxide. By sintering said .alpha.-alumina, there is obtained sintered .alpha.-alumina.

Method for manufacture of sintered alumina from ammonium aluminum

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Nagoya, Japan

Takeo Iga