Wear mechanism and preventive method of silicon electrodes in micro ECM

In micro electrochemical machining (ECM), sidewall-insulated electrodes are often used to constrain stray current and improve processing localization. Our research team has proposed a silicon electrode with outstanding sidewall-insulation performance. However, abnormal wear of silicon electrodes occurred in experiments. For the excellent insulation performance of silicon electrodes and their exploitability in micro ECM, this research aims to reveal the wear mechanism of silicon electrodes and prevent the wear of silicon electrodes. Through experimental and theoretical analysis, it is found that the wear of silicon electrodes is caused by alternating generation and dissolution of silicon hydrides during the electrolysis process. To be more specific, the generation of silicon hydrides is caused by the invasion of hydrogen atoms into silicon crystal during pulse width period, and their dissolution is aroused by the reverse current during inter pulse period. According to the wear mechanism, reverse current is eliminated to prevent the dissolution of silicon hydrides, thereby preventing electrodes wear. The reverse current is eliminated by replacing the original power supply, a pulse power supply with inter pulse depolarization loop (DePPS), with a pulse power supply without inter pulse depolarization loop (NDePPS) or with a DC power supply (DCPS). Micro ECM experiments are carried out under the NDePPS and the DCPS. Micro grooves with steep sidewalls are obtained under both power supplies. There is no wear of silicon electrodes after a long period of continuous use. The experimental results indicate the wear of silicon electrodes has been successfully prevented.