Fabrication of grinding tool material by the SHS of Ni–Al/diamond/dilute

Abstract

A mixture of Ni–Cr–P, Cu and B powder was used as a dilute for modifying the microstructure of the reacted product and easing the fast propagating rate and the high temperature in the self-propagating high-temperature synthesis (SHS) of Ni–Al matrix grinding tool material. The SHS process of the Ni–Al/diamond/dilute was examined and the microstructure of the reacted product was analyzed by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The grinding performance of the tool was tested in the grinding of a synthetic single crystal of sapphire. The results showed that the dilute substantially reduced the propagating rate and the combustion temperature of Ni–Al SHS. Besides the dominating intermetallics NiAl and NiAl 3, Ni 4Al 3 was also identified in the reacted Ni–Al/diamond/dilute composite owing to the Ni rich environment. In the reacted composite there was a Cr-rich zone at the boundary of the diamond grit due to the formation of Cr 3C 2 between Cr and the diamond. In the grinding a lower wear rate and a better retention ability of diamond grits could be achieved for the grinding tool material that contained finer diamond grits.