| 摘要 |
A composite construction 1 is obtained by coating the outer periphery of a core material 2 with a shell layer 3. The core material 2 is composed of a first sintered body that is obtained by bonding, with a binder metal, a first hard particle composed of one or more of carbides, nitrides and carbonitrides of metals of Groups 4a, 5a and 6a of the Periodic Table, or a first ceramics obtained by bonding, with a sintering additive, a first ceramic particle composed of at least one of oxides, carbides, nitrides and carbonitrides selected from the group consisting of metals of Groups 4a, 5a and 6a of the Periodic Table, Al, Si and Zn. The shell layer 3 is composed of a second hard sintered body or second ceramics having a different composition from the first hard sintered body. The ratio of the residual free carbon amount Cin in the core material 2 to the residual free carbon amount Cout in the shell layer 3, Cin/Cout, is 0.5 to 2. This prevents shrinkage during the time of sintering and also prevents the strength of the composite construction from lowering due to poor sintering.
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