Tribological behavior of WC-Co-CaF2 self-lubricating cemented carbides

In this study, CaF2 was introduced into WC-Co to prepare bulk self-lubricating cemented carbides by sinter-HIP. The studied compositions were WC-12Co with no more than 20 vol% CaF2 additions. The effects of CaF2 on the tribological behaviors and mechanical properties of cemented carbides were investigated. It was found that the prepared self-lubricating cemented carbides with CaF2 were nearly fully dense and CaF2 would refine the WC grains. Although CaF2 could not obviously enhance the mechanical properties of cemented carbides, it improved their tribological behaviors remarkably. The friction coefficient and wear loss during dry sliding could be reduced noticeably by the introduction of CaF2. The mechanism of tribological performance improvement was attributed to the lubricating film formation during the friction process. It would avoid direct contact between the friction counterparts and prevent severe wear of the materials. This study provides a new promising approach for cemented carbides to achieve better tribological performances by the self-lubrication design.