Coated cutting tool

摘要

A ceramic cutting tool comprises a ceramic base member 4 of a tool main body 1 which is formed of a composite ceramic which contains a hard phase dispersed within an alumina matrix phase. The hard phase contains, as a predominant component, one or more elements selected from hard-phase-forming metal elements M in the form of at least a carbide, a nitride, or a boride, or in the form of a solid solution of at least two selected from the carbide, the nitride, and the boride. The hard-phase-forming metal elements M include Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, and Si. The surface of the ceramic base member 4 is covered with a coating layer 1f, which contains titanium carbonitride or titanium nitride as a predominant component. The coating layer 1f has an average crystal-grain size of 0.1 to 0.5 mu m as observed on the surface, and an average thickness of 0.5 to 2 mu m. The coating layer 1f is formed through CVD performed in a low to medium temperature range of 750 to 900 DEG C. The ceramic cutting tool can be fabricated at low cost and can secure stable cutting performance over a long period even when the tool is used under severe cutting conditions under which large thermal and mechanical loads act on the tool.