WC-Ni계 초경합금의 기계적 성질에 미치는 Si의 영향

Abstract

The purpose of this study is to prescribe the influence of Si in WC-Ni Hard Metal. For the manufacture of WC-Ni Hard Metal according to Si content, the researcher manufactured WC-Ni mixed powder which 0wt.%~1.5wt.% of Si was added to after selecting Ni which a fixed amount of B was added to, and then manufactured sintered body by implementing vacuum-sintering to the mixed powder. This study implemented the analysis with HRA, TRS, XRD, SEM, and EPMA to observe densification, alloying reaction, and mechanical properties of the sintered body. In WC-Ni Hard Metal, shrinkage showed a tendency to increase as Si content increased. It is considered that the densification was promoted during liquid phase sintering, because a melting point of binder metal got lower as Si content increased. The hardness of WC-Ni Hard Metal was kept uniformly up to 0.6wt.%Si, and then it showed the tendency to increase from the level of 0.9wt.%Si. It is considered that the hardness of B and Si added to Ni binder metal formed BNi3 phase and Ni3Si phase which had high hardness, and these compound phase restrained the growth of WC particle. It is considered that transverse rupture strength of WC-Ni Hard Metal according to the increase of Si content was increased by the decrease of mean free path of WC particle caused by the improvement of fluidity according to the restrained growth of WC particle by of BNi3 phase and Ni3Si phase, and caused by the improved fluidity according to the decreased melting point of Ni binder metal.