Local surface smoothness on TC4 alloy during microbubbles flow electrolytic plasma polishing: prototype rig, phenomena, and mechanism

This paper introduces a microbubbles flow electrolytic plasma polishing (MF-EPP), which is based on electrolytic plasma polishing (EPP), but allows for local control polishing. MF-EPP energy consumption is lower, only 70–90 W power supply can complete the processing. Using Ti-6Al-4 V alloy sample as the polishing object, design and construct the original prototype to conduct theoretical and experimental research on the polishing process. The results show that the polishing solution has a stable polishing performance at a voltage of 210–430 V, functioning as a flexible polishing head, forming a circular polishing area of 14 mm in diameter on the workpiece surface, and reducing the surface roughness of polishing area from Ra 0.546 to 0.081 µm within 180 s. The processing phenomena, voltage and current characteristics, and surface morphology of the specimen are analyzed. Importantly, macroscopic and microscopic “pin-plate” models are proposed to elucidate the formation mechanism of MF (microbubbles flow) and the polishing mechanism of MF-EPP.