Comparison and Evaluation of Electrode Erosion Under High-Pulsed Current Discharges in Air and Water Mediums

In order to analyze the electrode erosion rate and erosion mechanism under high-pulsed current discharge in water and air, the erosion characteristics of the tungsten-copper (W-Cu) electrode under high-pulsed current were comparatively studied in the experiments. Based on the weight loss measurement, the cathode erosion rate, the anode erosion rate, and the total erosion rate of the electrodes discharged in water and air are obtained. Then the eroded surfaces after 100 shots are analyzed by electron transfer dissociation and energy dispersive X-ray spectroscopy, and concentrations of the metal ions after discharge in the water are measured and analyzed. Results show that the erosion of W-Cu electrode in water is more serious than that in air. Macromorphology of the eroded electrodes in water indicates that there are obvious arc spots caused by more focused arc and higher current density, leading to more serious erosion. Micromorphology shows that the electrode erosion in water is mainly caused by the evaporation of the metal, while the jet of the molten metal in air is the major erosion form. Apart from physical erosion caused by metal ablation and evaporation, the complex electrochemistry reaction, which is induced by the high-temperature arc in water, is one of the significant causes resulting in more serious erosion in water.