Patents by Inventor Kazuho Tatemasu

Kazuho Tatemasu 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).

  • Silicon nitride base ceramic heater element and method of producing same
    Patent number: 4912305
    Abstract: The invention relates to a ceramic heater element consisting of a sintered body of a silicon nitride base ceramic and a resistance heating wire such as a tungsten wire embedded in the ceramic body. The ceramic contains Al.sub.2 O.sub.3 and AlN besides Si.sub.3 N.sub.4 and is produced by using Y.sub.2 O.sub.3 as sintering aid. The ceramic body is improved in strength and also in stability of the ceramic structure at temperatures up to about 1300.degree. C. by rendering the grain boundary phase of the sintered ceramic a crystalline phase comprising either 2Y.sub.2 O.sub.3.Si.sub.2-x Al.sub.x N.sub.2-x O.sub.1-x (0.ltoreq.x<2) or 3Y.sub.2 O.sub.3.5Al.sub.2 O.sub.3. The heater element is produced by preparing a powder mixture in which (Si.sub.3 N.sub.4 +Al.sub.2 O.sub.3 +AlN) amounts to 90-98 wt %, the balance being the sintering aid, with proviso that (Al.sub.2 O.sub.3 +AlN)/Si.sub.3 N.sub.4 is from 0.02 to 0.08 by weight and that (Al.sub.2 O.sub.3 /AlN) is from 0.2 to 2.
    Type: Grant
    Filed: May 30, 1989
    Date of Patent: March 27, 1990
    Assignee: NGK Spark Plug Co., Ltd.
    Inventors: Kazuho Tatemasu, Yukihiro Kimura, Yoshiro Noda