The effect of graphite doping on the microstructure and properties of polycrystalline diamond compact

To investigate the effects of graphite doping on the microstructure and thermal and mechanical properties of PDC, this study prepared a series of samples with different graphite doping schemes using HPHT technology and conducted a systematic analysis using a combination of microscopic and macroscopic characterization techniques. The results indicate that under HPHT sintering conditions, PDC specimens with graphite doping exhibited no cracks or defects in their overall appearance. Furthermore, when the graphite powder doping content reached 5 wt%, the thermal expansion temperature point reached 929 °C, an increase of over 40 °C compared to the original PDC; But, as the graphite doping content increased, the bonding strength between diamond grains decreased, and the PDC’s wear behavior shifted from micro-cutting of the hard phase to fatigue spalling of the soft phase. In particular, when the graphite powder doping content reached 40 wt%, localized cobalt-depleted zones appeared in the PDC, significantly impairing the wear resistance of the PDC samples.