Study on cobalt removal process of PDC by pressurized chemical precipitation method

Polycrystalline diamond compact (PDC) needs to remove cobalt from diamond layer to improve wear resistance and impact resistance. The traditional cobalt removal process has low efficiency and long time. In this paper, a mixed solvent of hydrochloric acid and Lewis acid (FeCl3) was used as cobalt removal reagents, pressurized chemical precipitation method was used to study the cobalt removal of PDC. The effects of different reagent ratio, reaction temperature and reaction pressure on the surface morphology and de‑cobalt depth of PDC were studied. The holes morphology of PDC surface after cobalt removal was analyzed by SEM and ImageJ2x image analysis software. The fractal dimension of the holes on the PDC surface was calculated by the Area-circumference method, and the relationship between fractal dimension of hole and de‑cobalt depth was studied. The results show that the cobalt in PDC can be efficiently removed by pressure chemical precipitation method. The relationship between fractal dimension of the holes and the depth of cobalt removal is established. The cobalt removal efficiency of pressurized chemical precipitation method is higher than that of conventional acid leaching method. After cobalt removal, the wear resistance and impact toughness of PDC are further improved. [Display omitted] •Cobalt removal process of pressurized chemical precipitation method•De‑cobalt depth increases by pressurized chemical precipitation method•Positive correlation between surface morphology of PDC and de‑cobalt depth.•The fractal dimension can detect quickly de‑cobalt depth