Research on vacuum brazing of W-coated diamond with Ni-based filler alloy

Abstract

In order to alleviate the thermal damage and residual stresses of brazed diamond joints with Ni-based filler, W-coated diamond grains were used instead of conventional diamond grains and brazed onto 1045 steel substrates. The bonding interface properties, thermal damage and residual stresses of brazed W-coated diamond joints were investigated and studied. The results showed that the Ni-based filler exhibited good wettability to the W-coated diamond grains, and that the number and size of cracks at the bond interface of brazed W-coated diamond joints were significantly reduced compared with those of brazed conventional diamond joints. A dense and orderly Cr3C2 layer was generated on the surface of conventional diamond, while the disordered granular Cr3C2 growing into the filler alloy was formed on the surface of W-coated diamonds. With the isolation and protection of the coating, the brazed W-coated diamond grain surface has lower graphitization and better mechanical properties. At the same time, the thinner and more reasonable morphology of Cr3C2 layer on the surface of W-coated diamond effectively relieves the residual stress, and its maximum residual compressive stress is reduced by 9.43% compared with that of conventional diamond