CUTTING TOOL HAVING BODY COATED BY HARD WEAR RESISTANT FILM

摘要

PROBLEM TO BE SOLVED: To provide a coated cutting tool for chip forming containing at least one layer of an alumina (Al2O3) which is formed by a film featured by fine equi-axed grain. SOLUTION: At least one layer substantially consists ofα-Al2O3 and a body at least partially coated by a plurality of heat resistant layers is provided. The layer of Al2O3 is formed of substantially equi-axed grain having an average grain size of 1μm or less and has bimodal grain size distribution consisting of coarse grains having an average grain size of 0.5-1μm and fine grains having an average grain size of up to 0.5μm. Further, a layer of Al2O3 contains a groove-form region containing titanium (at least 5 at.%) but containing neither nitrogen nor carbon. The special microscopic texture is achieved by temporarily stopping gas necessary to growth of a layer of Al2O3 and introducing TiCl4.