Advanced plasma electrolysis research equipment with in-situ process diagnostics

The article describes the development of a universal power supply and an in-situ impedance spectroscopy unit for plasma electrolysis research. Schematic solutions are based on the analysis of current-voltage and frequency response characteristics of the plasma electrolytic oxidation (PEO) process. The power supply has a modular structure, remote PC control and high power factor. Its flexible internal structure allows studies of the plasma electrolysis in DC, bipolar and unipolar modes with broad variation in the pulse frequency, magnitude and duty cycles. The software part of the equipment allows the power supply control, registration of instantaneous values of current and voltage from the sensors, and necessary mathematical calculations. The in-situ impedance spectroscopy unit is operated in a step-sweep frequency mode, and it helps in diagnostics of the equivalent circuit of the PEO process. The calibration results of the power supply and the impedance spectroscopy unit show the recommended frequency range for equipment application from 20 Hz to 20 kHz. The equipment was tested during PEO of titanium and zirconium alloys, and it showed the effectiveness of the proposed research methodology.