Ntk Cutting Tools Co., Ltd.

Tatsuya Toda

Takuya Furuhashi

Ryoji Toyoda

A cutting tool () formed of a silicon nitride-based sintered body () including a matrix phase (), a hard phase (), and a grain boundary phase () in which a glass phase () and a crystal phase () exist. The sintered body () contains yttrium in an amount of 5.0 wt % to 15.0 wt % in terms of an oxide, and contains titanium nitride as the hard phase () in an amount of 5.0 wt % to 25.0 wt %. In an X-ray diffraction peak, a halo pattern appears at 2θ ranging from 25° to 35° in an internal region of the sintered body (). A ratio B/A of a maximum peak intensity B to a maximum peak intensity A satisfies 0.11≤B/A≤0.40 . . . Expression (1) in a surface region of the sintered body (), and satisfies 0.00≤B/A≤0.10 . . . Expression (2) in the internal region of the sintered body ().

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Nagoya, Japan

Tatsuya Toda