Sumitomo Electric Industries, Limited

Takeshi Satoh

Akira Yamakawa

Hitoshi Sumiya

Masashi Yoshimura

Takao Nishioka

Hisao Takeuchi

Akira Yamaguchi

Masamichi Yamagiwa

Jin-Joo Park

A composite sintered body includes a diamond phase and a non-diamond carbon phase. A non-diamond carbon phase occupancy rate is higher than 0% and not higher than 30%. The non-diamond carbon phase occupancy rate is a percentage of an area of the non-diamond carbon phase to a total area of one arbitrarily specified cross section of the composite sintered body. As a result, there is provided a high wear-resistant, high local wear-resistant and high chipping-resistant diamond-containing composite sintered body suitably used as a material for a wear-resistant tool, a cutting tool and the like.

Composite sintered body

A composite sintered body includes a first phase and a second phase. The first phase is a diamond phase, and the second phase is a phase formed of one or more types of elements or compounds or both thereof and applying strain to the first phase. A contained amount of the second phase is larger than 0 ppm and not larger than 1000 ppm. As a result, there is provided a high wear-resistant, high local wear-resistant, and high chipping-resistant diamond-containing composite sintered body.

A producing method of a porous SiNhaving high porosity and formed of SiNparticles having a high aspect ratio includes the following steps. A compound of a rare earth element as a first sintering agent is mixed in an amount of 7.5&#x2013;45 parts by mass, in terms of an oxide of the element, with respect to 100 parts by mass of Si powder to obtain mixed powder. A binder is added to the mixed powder, which is then molded into a molded body. The molded body is heated in a nitrogen atmosphere to 300&#x2013;500&#xb0; C. to remove the binder. The binder-removed body is heated in a nitrogen atmosphere to 1350&#x2013;1500&#xb0; C. for nitriding. The nitrided body is then sintered at 1750&#x2013;1900&#xb0; C. at a nitrogen pressure of 0.1&#x2013;1 atmosphere.

[object Object]

A process for the production of a silicon nitride sintered body which comprises heat-treating a stock of silicon nitride sintered body within a temperature range of from the temperature at which the internal friction of the stock exhibits a peculiar peak maximum minus 150.degree. C. to that plus 150.degree. C. A representative used in the process is one which is produced by mixing powdered silicon nitride with powdery sintering aids so as to give a powder mixture comprising 5 to 15% by weight (in terms of oxide) of at least one element selected from the group consisting of rare earth elements and aluminum, 0.5 to 5% by weight (in terms of oxide) of at least one element selected from the group consisting of Mg, Ti and Ca and the balance of Si.sub.3 N.sub.4, molding the powder mixture, and sintering the resulting compact in a nitrogen-containing atmosphere at 1500.degree. to 1700.degree. C.

Growing community of inventors

Itami, Japan

Takeshi Satoh