Ngk Spark Plug Company, Limited

Kenji Nakanishi

Masakazu Watanabe

Yo Tajima

Kazuhiro Urashima

A sintered body of silicon nitride having high strength, toughness and oxidation resistance consists essentially of, by weight percentages, 0.5 to 7.0% of a Mg component calculated as MgO, 0.5 to 7.0% of a Zr component calculated as ZrO.sub.2, 0.5 to 10.0% of a Ce component calculated as CeO.sub.2, and the balance being Si.sub.3 N.sub.4. The sum of Mg, Zr and Ce components calculated as oxides is 3 to 20% by weight. This product is suitable for engine parts or cutting tools.

Silicon nitride sintered body

A silicon nitride sintered product comprises, in % by weight, 1 to 10% Mg, calculated as MgO, 1 to 10% Zr, calculated as ZrO.sub.2, 0.1 to 2.0% of at least one of Al, calculated as Al.sub.2 O.sub.3, Li, calculated as Li.sub.2 O, and Na, calculated as Na.sub.2 O, and the remainder being Si.sub.3 N.sub.4 and unavoidable impurities.

Growing community of inventors

Komaki, Japan

Kenji Nakanishi