| 摘要 |
PROBLEM TO BE SOLVED: To provide a cermet excellent in wear resistance and breaking resistance and having long service life by limiting the state of distribution of black phases in a cermet containing the carbides, nitrides, and carbonitrides of Ti and specific metals. SOLUTION: A powder mixture is prepared by mixing powders of hard compounds, such as the carbides, nitrides, and carbonitrides of Ti and group IVa, Va, VIa metals of the periodic table, other than Ti, e.g. Ta, Nb, W, Mo, V, and Zr, and a powder of metal, such as Co and Ni, acting as a binding material in the subsequent sintering stage. This powder mixture is compacted and then sintered at high temp., by which a hard cermet alloy is produced. This cermet alloy consists of 80-95% of hard phases and the balance binding phases, such as Co and Ni, and black phases. The black phases existsin the region between the position at a depth of 5μm and the position at a depth of 1000μm from the surface of the cermet alloy, at a proportion of 1-75% and, further, this proportion increases with the approach to the depth. Moreover, the hard phases exist dispersedly so that coarse grains and fine grains having a diameter less than one half the diameter of the coarse grains form a mixture fraction from 1:8 to 8:1 in the cross section of the cermet.
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