On the effect of substituting copper powder with cupric salt for the sintering process of W–Cu MIM Parts

This study was carried out for the feasibility of applying the Cu-contained binder to W–Cu MIM parts as the first step for the practical use. To methylcellulose–water solution (conventional binder), cupric salt was added to create the Cu-contained binder. In this experiment, the W–Cu powder mixture was used with the conventional binder and the Cu-contained binder which removed by thermal decomposition in air during the heating-up stage for sintering which was performed under hydrogen atmosphere. To test advantages of the Cu-contained binder in densification and homogenization of the specimen using it, unfavorable conditions (the lowered solid loading and the low level of copper powder purity) were selected. The parts processed in this way are dense and homogeneous, compared to ones not using cupric salt. The analysis of sintering density revealed that the Cu-contained binder made each factor less significant than the conventional binder. It alludes to the Cu-contained binder’s contribution to a W–Cu sintering process which makes a rearrangement of the W powder prior to the formation of W skeleton. In spite of the advantages of the Cu-contained binder, many problems still remain.