PURPOSE: For preventing the scrape-off of coating layer, to coat the surface of a hard metal with one or more kinds of the carbides or carbonitride of the metals belonging to groups IVa, Va and VIa of the preiodic law table and to provide one or multilayer coating of various kinds of nitrides, oxides and carbides on thus- obtained coating.
CONSTITUTION: The surface of a hard metal is coated with one or more kinds of the carbides or carbonitride of the metals belonging to groups IVa, Va and VIa of the periodic low table. A desired coating chip is obtained for milling cutters by including the coating layer of the nitride, carbonitride or carbonic nitride, or a mixture or compound thereof as one of the multicoating layers provided thereon. Thus-obtained chip generates no phase 7 on the boundary plane between said hard metal and the innermost coating layer at all and hardly causes the scrape-off of coating layers so that the life thereof is extended.
TOBIOKA MASAAKI
YAMAMOTO TAKAHARU
