Patents by Inventor Tetsuro Urakawa

Tetsuro Urakawa has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Method of manufacturing .beta. type silicon nitride whiskers
    Patent number: 4521393
    Abstract: Silicon nitride whiskers having a long fiber length in which .beta. type silicon nitride is well developed are produced by reacting a mixture of silica, carbon and cryolite in the specific molar ratio in a mixed gas atmosphere of N.sub.2 and NH.sub.3 by heating the mixture at a temperature of 1,250.degree.-1,450.degree. C. Kira of a ceramic industry waste may be used in place of silica and in this case N.sub.2 alone is used as a nitriding atmosphere.
    Type: Grant
    Filed: June 26, 1984
    Date of Patent: June 4, 1985
    Assignees: Toshiba Ceramics Co. Limited, Hajime Saito
    Inventors: Hajime Saito, Tetsuro Urakawa
  • Process for preparing silicon nitride powder
    Patent number: 4514370
    Abstract: Disclosed is a process for preparing silicon nitride powder, which comprises baking a powdery mixture comprising (i) 1 part by weight of silica powder, or a silica-containing substance in terms of silica, (ii) 0.4 to 4 parts by weight of carbon powder, or a substance generating carbon by baking, in terms of carbon and (iii) 0.005 to 1 part by weight of silicon nitride powder synthesized by a silica reduction method, at a temperature of from 1350.degree. to 1550.degree. C. in a non-oxidative atmosphere containing nitrogen.
    Type: Grant
    Filed: June 8, 1984
    Date of Patent: April 30, 1985
    Assignees: Tokyo Shibaura Denki Kabushiki Kaisha, Toshiba Ceramics Co., Ltd
    Inventors: Hiroshi Inoue, Katsutoshi Komeya, Akihiko Tsuge, Kazunari Koide, Masaaki Mori, Tetsuro Urakawa