COATED HARD ALLOY

摘要

A coated hard alloy for use in making cutting tools excellent in wear and chipping resistances. It is produced by forming a hard coating layer on the surface of a base material such as cemented carbide or cermet. The coating layer is composed of an inner layer (2) formed on the base material (1) and comprising titanium carbide, nitride, carbide-nitride, carbide-oxide, carbide-nitride-oxide or boride-nitride, an intermediate layer (3) formed on the inner layer (2) and comprising Al2O3 or ZrO2, and an outer layer (4) formed on the intermediate layer (3) and comprising titanium carbide, nitride, carbide-nitride, carbide-oxide, carbide-nitride-oxide or boride-nitride. The thickness of the inner layer (2) is 0.1-5 mu m, while the thickness of the intermediate layer (3) is 5-50 mu m in the case of Al2O3 or 0.5-20 mu m in the case of ZrO2, and the thickness of the outer layer (4) is 5-100 mu m.