Effects of process parameters on interfacial microstructure, residual stresses, and properties of tunnel furnace brazed diamonds

Abstract

Diamonds were brazed on the substrate with nickel‑chromium (NiCr) filler alloy at a certain temperature for three different mesh belt speeds in the mesh belt continuous tunnel furnace, respectively. In this study, a different perspective involving the exploration of the new processes was used that could allow for the mass production of brazed diamond tools. The interfacial microstructure between the diamonds and filler alloy was analyzed by scanning electron microscopy, energy dispersive spectrometry, and X-ray diffraction. The residual stresses and mechanical properties of the brazed diamonds were determined through the laser Raman spectrum and the compressive strength or impact toughness testing equipment for superabrasives, respectively. The results illustrated the occurrence of chemical reaction at the interface of the filler alloy-diamond followed by the formation of the CrC compound. Moreover, the thickness of the interfacial reaction layer increased with the decrease in the mesh belt speed. The brazing high temperature and development of the CrC layer were found to be responsible for the residual stresses in the diamonds. The mechanical properties of the brazed diamond grits strongly depended on the resultant thickness of the diamond surface and the residual stresses produced during brazing.