The polishing of diamond and diamond composite materials

Abstract

Measurements were made of the rates of removal of material when diamond and diamond composites are polished on a cast iron scaife charged with diamond powder, and on a polishing wheel in which diamond powder is bonded into a metal matrix. Consistent and reproducible values are obtained provided that the cast iron scaife is kept adequately charged with diamond powder. Composite material may then be polished faster than single-crystal diamond, even though many of the diamond crystallites present themselves in unfavourable directions for polish. This relatively high removal rate appears to arise because the polishing powder may sink into the binder of the composite and abrade the edges of the diamond crystallites as well as their surface. The experiments also show that the rate of polish of diamond depends on the degree of subsurface damage produced by previous polishing, and that the cracking and polishing of diamond at low speed is aided by the presence of an atmosphere of air.