Experimental investigation on reducing friction-induced graphitization in cobalt removal polycrystalline diamond compact (PDC)

Abstract Polycrystalline diamond compact (PDC) has excellent wear resistance, making it widely utilized in drill bits and bearings of downhole tools within the oil industry. However, the harsh conditions underground and the friction place higher demands on the performance of PDC. However, the harsh conditions underground and the friction place higher demands on the performance of PDC, leading to a severe deterioration in both wear resistance and chemical stability. To address this issue, the present work investigates cobalt removal PDC subjected to high-temperature annealing to evaluate its degree of graphitization and chemical stability. The annealing experiment was carried out by box resistance furnace. The microstructure of PDC after annealing and friction wear was examined using scanning electron microscope (SEM) and energy dispersive spectrometer (EDS). Additionally, the evolution of chemical bonds after PDC wear was analyzed by X-ray photoelectron spectroscopy (XPS). The results show that with increasing annealing temperature, the area of PDC wear-resistant interface transfer film is increasing. In contrast, the non-cobalt removal PDC not only failed to develop a transfer film at the wear interface but also exhibited pronounced graphitization. These experimental findings and mechanistic insights offer a theoretical basis for guiding the application of PDC in downhole tools for petroleum drilling.