Investigation of the friction and wear characteristics of polycrystalline diamond compact in a wide temperature range

The friction and wear behaviours of polycrystalline diamond compact (PDC) at temperatures ranging from room temperature to 600 degrees C are evaluated using a pin-on-disc high-temperature tribometer, and the microstructures and chemical compositions of the worn PDC surfaces are analysed experimentally. The results show that the friction coefficient of PDC is significantly affected by temperature; the friction coefficient decreases with increasing temperature below 200 degrees C and increases with increasing temperature above 200 degrees C; the friction coefficient is the lowest at 200 degrees C, with a value of 0.048. The fluctuation of the friction coefficient with temperature is related to the different synthesis results of surface deformations and tribochemical reactions during the sliding tests at different temperatures. The exfoliation of the diamond grains and Co phase from the PDC surface results in a scratched appearance on the PDC surface, which has a friction-increasing effect and dominates at temperatures above 200 degrees C. The cobalt oxides and graphite formed on the PDC surface can operate as solid lubricants to decrease the interfacial friction of the PDC, which has a friction-decreasing effect and dominates at temperatures below 200 degrees C.