Effect of CeSi2 addition on microstructures of brazed layers and interfacial characteristics of brazed diamonds with Ni Cr filler alloy

The thermal damage of diamond is the key factor restricting the performance of brazed diamond tools with Ni-based filler. Hence, the NiCr filler alloy is modified by adding Ce element to reduce the graphitization and improve the mechanical properties of brazed diamond in this work. The results indicate that the microstructures of brazed layers with NiCr filler containing Ce element are obviously refined, and the brazed layer containing 2 wt.% CeSi2 shows the better wear resistance with stable friction coefficient curve and low wear loss. Meanwhile, the brazed diamond with NiCr filler containing 2 wt.% CeSi2 exhibits a higher exposure, and the Cr3C2 on its surface is finer, which contributes to reduce the stress concentration and cracks formation at interface between diamond and filler. The Raman spectrum results show that the graphitization of brazed diamond is significantly weakened due to addition of CeSi2. The NiCr filler brazed diamonds containing 2% CeSi2 remain relatively complete cutting edges and shapes after grinding test, showing the excellent wear resistance. Moreover, the calculation of elastic properties indicates that the in-situ formed CeNi3 phase exhibits better ductility and plasticity, but lower hardness, and its formation is beneficial to improve the ductility and plasticity of brazed layer.