The Al₂O₃ coating prepared by cathode plasma electrolytic deposition (CPED) can significantly improve the the corrosion resistance and wear resistance of the stainless steel. However, few researches about the insulation property of Al₂O₃ coating on stainless steel were reported.

     The Al₂O₃ insulating coating was prepared on the 304 stainless steel by CPED. The influence of different electric parameters and the deposition time on the insulation properties of the Al₂O₃ coating were investigated in the present study. The results suggested that the thickness and the breakdown voltage of the coating generally increased with the synergy increase of the voltage and the duty cycle within a certain range. With the increase of the frequency, the thickness and the breakdown voltage decreased first and then increased. Additionally, with the increase of the deposition time, the thickness and breakdown voltage increased first and decreased later while the voltage was 300V, the duty cycle was 80% and the frequency was 1500Hz. When the deposition time was 8min, the thickness reached 66μm, the breakdown voltage reached the top of 650V, and the insulation property of the coating was the best. At last, the mechanism of the effect of oxidation time on the insulation property of the coating was explained.

     This work fills the gap in the study of the insulation property of the Al2O3 coating prepared by CPED on stainless steel and provides important technical support for the insulation of stainless steel parts of the switch.