Effect of Ni–Al SHS reaction on diamond grit for fabrication of diamond tool material

Diamond grits were added to Ni–Al self-propagating high-temperature synthesis system for fabrication of diamond tool materials. The propagating processes and the microstructure of the reacted composite were investigated. The surface characteristics of diamond grits after Ni–Al SHS reaction were examined by scanning electron microscopy (SEM) and Raman spectroscopic analysis. Owing to the presence of diamond grits, the flame-front propagation velocity of Ni–Al/diamond was reduced by 33% comparing to that of Ni–Al. Intermetallics such as NiAl, Ni2Al3, Ni3Al and NiAl3 were identified in the reacted Ni–Al/diamond composite. Due to the high temperature of Ni–Al SHS, some of the diamond grits’ surface was graphitised. There were a large number of craters on the surface of graphitised diamond grits, in which the spherical and rod-like graphite particles were found. The mean compressive strength of the SHS-treated diamond grits decreased about 20% comparing to that of the initial diamond grits.