Analysis on brazed diamond joints with modified Cu-based filler alloy

Filler alloy can strongly influence the performance of brazed monolayer diamond grinding tools. Cu-Sn-Ti and modified Cu-based filler alloy added with Ni-Cr-B-Si were used to braze diamond. The morphology of the diamond and the microstructure of the filler alloy were analyzed by SEM, EDS, and XRD. The hardness of the alloy was also determined with a microhardness tester. The results show that filler alloy containing Cu, Sn metal powder, and 16%Ni-Cr-B-Si is suitable for brazing diamond. The morphology of the brazed diamond is intact, and the filler alloy catalyzes the chemical metallurgical bonding with the diamond. Different kinds of carbide are formed on different crystal faces of the diamond. Cu-based dendrites, Cu5.6Sn, Cu3Sn, and Ni3Sn are formed on the filler alloy during solidification. The hardness of the modified Cu-based filler alloy increases with increasing proportion of Ni-Cr-B-Si added. In particular, the hardness of the modified Cu-based filler alloy containing 16 wt% Ni-Cr-B-Si reaches 340-360 HV0.3, which is three times the hardness of the Cu-Sn-Ti filler metal.