THE WEAR MECHANISMS OF IMPREGNATED DIAMOND BITS

An experimental study was carried out to investigate the wear mechanis ms of impregnated diamond bits in hard rock drilling. Rock cutting exp eriments with single-diamond were performed to measure the coefficient of friction and to understand the tribological process at the diamond /rock interface. The coefficient of friction strongly depended on the characteristics of rock fracture at contacting rock surface. It ranges from 0.035 to 0.065 if diamonds slid over the rock surface without si gnificant local bulk fracture. Otherwise, the coefficient of friction between the diamond and rock could vary from 0.05 to 0.5 depending on the rock types tested. Impregnated diamond micro-bit drilling tests we re conducted to observe the wear processes of both diamond and metal m atrix at various drilling conditions. It was found that the penetratio n per revolution was the predominant parameter influencing the wear be havior of the impregnated diamond bits. The study indicated that the w ear characteristics of impregnated diamond bits depended not only on t heir structure and material properties but also on the operational par ameters of rock drilling.