PURPOSE: To prevent the occurrence of peeling to a covering layer and to provide excellent cutting performance for a long period by distributing an iron metal of one or more kind of Fe, Ni, and Co in a given thickness in a given range at a boundary part between a gas phase synthetic diamond covering layer and a substrate surface.
CONSTITUTION: In prior to form a gas phase synthetic diamond covering layer on the surface of a substrate formed of a WC super alloy, various thermet, and ceramics, an iron metal layer formed of Fe, Ni, and Co and one or more of two or more kinds of alloys of them in an extremely thin thickness within a range of 0.001-1μm is formed on the surface of the substrate. Since, by forming the diamond covering layer in this state by a gas phase synthetic method, synthesis of a diamond is effected as the iron metal is inputted, the formed gas phase synthetic diamond covering layer is a substance wherein the iron metal is distributed in a given thickness in a range of 0.001-1μm at a boundary between the covering layer and the substrate surface, and adhesion of the interface part to the substrate surface is sharply increased.
MACHI YOSHIO
KOBAYASHI KENJI
MUTSUKURA NOBUKI