Study on the preparation of Ni Al intermetallic-bonded diamond grinding block and grinding performance for sapphire

Abstract

At present, high-quality thinning processing of sapphire puts forward higher requirements on the sharpness and shape retention of diamond grinding wheels. There is thereby an urgent need to find a kind of bond material with moderate holding force on diamond to promote the performance of diamond grinding wheels. In this study, a novel NiAl intermetallic-bonded diamond grinding block is developed. NiAl gas-atomized pre-alloyed powders are used as bonds to endow materials with lower oxygen content and great flexural strength. Moreover, Cu3Sn with low melting point is introduced in the diamond grinding block to reduce sintering temperature and thermal damage of diamond. The NiAl intermetallic-bonded diamond grinding block containing 5 wt% Cu3Sn with flexural strength of 89 MPa and porosity of 0.67 % presents the best grinding performance for sapphire. After grinding, the wear rate, wear ratio and surface roughness of the sapphire are 319.93 mm3/min, 36.9 and 1.09 μm, respectively. The proper holding force of bonds on the diamond ensures that diamonds could fall off when the edges become slightly blunt, which contributes to the great sharpness and shape retention of grinding blocks.