Скачать или смотреть Instabilities in plasma electrolytic oxidation under bipolar polarisation, SSET-2024, Manchester

Abstract: Plasma electrolytic oxidation is an environmentally friendly coating technique applicable to valve metals like Mg, Al, Ti etc. The PEO process is featured by generation of multiple local breakdowns as a response to high-voltage polarisation. Necessity to control the energy of the microdischarges led to the evolution of electrical modes from DC to multistep waveforms, including pulses of various polarities sequenced in a complex manner. Such non-stationary conditions result in a spontaneous evolution of the PEO to soft-sparking mode with collective spatial-temporal instabilities. In this work, we have attempted to analyse instabilities in growing PEO coating. We demonstrate that the electrical response of the PEO electrode may behave as the N- and S-type on the j-E plane, indicating negative and positive feedback. It is shown that switching between N and S response depends on the history of the film and can be employed in practice of intelligent coating deposition techniques.