Patents by Inventor Michitaka Mizutani

Michitaka Mizutani 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).

  • Process for preparation of sintered silicon nitride body
    Patent number: 4643858
    Abstract: In preparing a sintered silicon nitride body by hot isostatic pressing, if a green molded body of silicon nitride and a sintering aid is coated with a compound of high melting point cyrstalline powder (sintering aids of silicon nitride), said crystalline compound works as a pressure media on HIP treatment and is present in the surface of the sintered body. By the presence of this crystal, hot isostatic pressing of this dual density compact mentioned above results surface compression stress, which results not only the strength at room temperature but also the strength at high temperatures is highly improved.
    Type: Grant
    Filed: March 5, 1985
    Date of Patent: February 17, 1987
    Assignee: Kyocera Corporation
    Inventor: Michitaka Mizutani
  • Sintered silicon nitride body
    Patent number: 4628039
    Abstract: Disclosed is a sintered ceramic body having a composition comprising (i) Si.sub.3 N.sub.4, (ii) a combination of an oxide of an element of the group IIIa of the Periodic Table having an ionic radius smaller than 0.97 .ANG. and an oxide of other element of the group IIIa of the Periodic Table, having an ionic radius larger than 0.97.degree. and (iii) an oxide or nitride of at least one of the following: (1) at least one element of group IIa of the Periodic Table; (2) Al; (3) Ti; (4) Cr; (5) Ga; (6) Zr; and (7) Si. This sintered silicon nitride body shows a high oxidation resistance when it is used for a long time at high temperatures, and the sintered body is excellent in the creep characteristics and flexural strength at high temperatures.
    Type: Grant
    Filed: March 5, 1985
    Date of Patent: December 9, 1986
    Assignee: Kyocera Corporation
    Inventors: Michitaka Mizutani, Kiyoshi Yokoyama
  • Process for preparation sintered silicon nitride body having surface compression stress
    Patent number: 4622186
    Abstract: In preparing a sintered silicon nitride body by hot isostatic pressing, a composition comprising Si.sub.3 N.sub.4 and a sintering aid is molded to form a green molded body, the surface of the green molded body is coated with a composition comprising Si.sub.3 N.sub.4 and a sintering aid and having a sintering temperature lower than that of the composition of the green molded body, the coated green molded body is preliminarily sintered so that only the coating layer is densified, and the preliminarily sintered molded body is subjected to hot isostatic pressing. The obtained sintered body has a surface compression stress, and by this surface compression stress, not only the strength at room temperature but also the strength at high temperatures is improved.
    Type: Grant
    Filed: March 5, 1985
    Date of Patent: November 11, 1986
    Assignee: Kyocera Corporation
    Inventor: Michitaka Mizutani