Investigation of the plasma electrolytic oxidation of Ti6Al4V under single-pulse power supply

Plasma electrolytic oxidation (PEO) was studied using electrochemical impedance spectroscopy (EIS) and transient waveform analysis. First, EIS measurements on coatings prepared under constant current density were conducted in the working electrolyte. The EIS analysis showed that the coating structure changed with the termination voltage. Second, the pulse waveform of the power supply was recorded during the PEO process. It showed that a charging process occurred across the breakdown coating at the beginning of the pulse. The present study analysed this charging process in detail.

► Growth process of PEO coating is analysed by EIS and transient waveform methods.
► Variation of coating structure during the growth is well reflected by EIS results.
► Transient analysis procedure is applied to PEO process for the first time.
► Structure character of the breakdown coating is obtained by transient method.