| 摘要 |
PROBLEM TO BE SOLVED: To prevent the progressing of crack on a coating layer and the peeling of a coating interface and to hardly cause the chipping by coating the inner layer of the carbide, etc., of 4a group metal, etc., on the surface of a hard alloy base body and aluminum oxide layer ofθtype at the base alloy side and K type at other parts. SOLUTION: On the surface of the hard alloy base body composed of a hard phase of the hard alloy, cermet, etc., and a combined phase, the inner layer composed of one kind of a single layer or two or more kinds of multi- layer among the carbide, nitride, oxide of 4a, 5a, 6a group metals in the periodic table and solid solution or mixed body thereof is formed. Further, the aluminum oxide layer is coated on the inner layer. This aluminum oxide layer is formed as the layer consisting essentially of the softθtype aluminum oxide at the base body side in contact with the inner layer and the layer consisting essentially of the hard K type aluminum oxide excellent in the wear resistance, oxidizing resistance and chipping treatment property at the part except the base body side, and it is desirable that the average thickness of theθtype aluminum oxide is regulated to 0.01-0.4μm. In this way, the coated hard alloy excellent in the chipping resistance and the adhesibility is obtd.
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