Sintokogio, Ltd.

Other

Ngk Spark Plug Company, Limited

Japan Science and Technology Agency

Nagoya University

Sinto V-cerax, Ltd.

Hiroyasu Saka

Masakazu Watanabe

Satoshi Iio

Hideki Morimitsu

Toru Imura

Syoji Uchimura

Toshiro Ito

Kotaro Kuroda

Won-Jin Mooni

Shouji Uchimura

A ceramics sintered material cutting tool, characterizing in that it has a dislocation structure which formed on the surface thereof in a straight line from and distributed uniformity in a dislocation density of 1&#xd7;10to 9&#xd7;10cm. The cutting tool is improved in a fracture toughness value and the resistance to thermal shock and thus has a prolonged life. The above cutting tools include, in particular, a twist drill and a throw away tip.

Method for toughening surface of sintered material cutting tool and sintered material cutting tool having long life

When a sintered body of ceramic is shot-blasted at normal temperatures to plastically deform the crystal structure of the shot-blasted surface to apply residual stress and is heat-treated to recrystallize fine cracks, dislocated cells in the grain boundary are formed, crystals are finely divided, and the fracture toughness is significantly improved. When the sintered body of ceramic is a thin product, an effective toughening can be attained by shot blasting both the front and back sides. After heat treatment, mechanical strength is significantly improved by removing a part of the modified surface layer by an abrasion treatment.

Method of toughening and modifying ceramic and ceramic products

A zirconia-base sintered body comprising a sintered substrate containing 30% by volume or more of tetragonal zirconia and a coating film disposed thereon, characterized in that the diffusion coefficient of oxygen in a material forming said coating film at no higher than 550.degree. C. is smaller than that of oxygen in said tetragonal zirconia at a temperature of no higher than said temperature.

Zirconia-base sintered bodies having coating films

Growing community of inventors

Aichi, Japan

Hiroyasu Saka