Ngk Spark Plug Company, Limited

Hiroko Nakayama

Kazuhiro Urashima

Atsushi Komura

Ryoji Toyoda

A silicon nitride-based sintered body containing silicon nitride-based grains, which are silicon nitride grains or sialon grains. In the silicon nitride-based sintered body, when the size of each silicon nitride-based grain is represented by its maximum grain size, the ratio of the number of silicon nitride-based grains having a maximum grain size of 1 &#x3bc;m or less to the number of the entire silicon nitride-based grains is 70% or higher. Furthermore, in the distribution profile of no. % of silicon nitride-based grains with respect to maximum grain size, the maximum value of no. % (i.e., maximum no. %) of silicon nitride-based grains is 15 no. % or higher. Also disclosed is a cutting insert, which is formed of the silicon nitride-based sintered body.

Silicon nitride-based sintered body and cutting insert

The present invention provides a technique of improving wear resistance of a Sialon sintered body. The Sialon sintered body has a Sialon phase including at least a &#x3b2;-Sialon and a 12H-Sialon among an &#x3b1;-Sialon, the &#x3b2;-Sialon and the 12H-Sialon. A ratio of a second Sialon total content, which is a sum of the contents of the &#x3b1;-Sialon and the 12H-Sialon, to a first Sialon total content, which is a sum of contents of the &#x3b1;-Sialon, the &#x3b2;-Sialon and the 12H-Sialon, is greater than 20% and not greater than 55%, and a ratio of the content of the 12H-Sialon to the first Sialon total content is not less than 2% and not greater than 55%.

Sialon sintered body and cutting insert

A cutting insertis made of an aluminum oxide-based composite sintered body constituted by a ternary ceramic material including aluminum oxide, silicon carbide, and a sialon. The sialon in the aluminum oxide-based composite sintered body is Si&#x2014;Al&#x2014;O&#x2014;N as defined by JCPDS No. 32-0026 in X-ray diffraction analysis.

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Komaki, Japan

Hiroko Nakayama