| 摘要 |
PROBLEM TO BE SOLVED: To solve the problem of simultaneous improvement in the wear resistance and breakage resistance of a cermet tool, which has so far been a difficult problem in the case of a cermet tool having a hard surface layer formed by atmospheric heating because breakage resistance is greatly deteriorated in this case through wear resistance can be improved. SOLUTION: This cermet tool is constituted by providing a hard nitrided layer, formed by nitriding treatment, onto a part or the whole of the surface of a sintered alloy which consists of 5-30wt.% of binding phase, composed essentially of Co and/or Ni, and the balance hard phase, composed essentially of at least one Ti-containing compound selected from the group consisting of the carbides, nitrides, and carbonitrides of Ti and the compound carbides, compound nitrides, and compound carbonitrides containing Ti and one or more kinds, excluding Ti, among the group IVa, Va, and VIa metals of the periodic table, with inevitable impurities. At this time, the hard nitrided layer consists of an in-layer binding phase, composed of <=2wt.% of binding phase, and the balance in-layer hard phase having nitrogen content higher than the average nitrogen content of the hard phase and shows a columnar crystal in which the crystalline grains of the in-layer hard phase are arranged perpendicularly to the surface of the hard nitrided layer, and further, the layer thickness of the hard nitrided layer is regulated to 0.5-15μm.
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