Effect of ultrasound on cobalt removal from PDC in a weak acid electrolyte

The cobalt binder used in the synthesis of polycrystalline diamond compact (PDC) is negative to its service performance, while cobalt removal from PDC is a common way to recover this problem. In order to improve the efficiency of cobalt removal from PDC in a weak acid electrolyte, the effects of ultrasound on the electrolysis process of PDC were investigated in this study. The role of ultrasound in the electrode process was studied by electrochemical methods, and the effect of ultrasound on depth of cobalt removal was evaluated by scanning electron microscope (SEM) and energy dispersive spectroscopy (EDS). The experimental results showed that ultrasound reduced the charge transfer resistance of solution and the film resistance of PDC surface, thus cleaner PDC surface, faster rate and deeper depth of cobalt removal can be obtained. More specifically, the corrosion current density increased by 0.6 times, and the depth of cobalt removal increased by 194 μm. Therefore, ultrasound assisted electrolysis provides an effective and practically feasible method for cobalt removal from PDC.