Plasma Electrolytic Oxidation (PEO) technology is an effective means of improving the surface properties of metal parts, but this method is not applicable to the non-valve metal 304 stainless steel. Because 304 stainless steel contains a large amount of chromium, the chromium will hinder the voltage rise in the PEO process, which will lead to the failure of the PEO process. In order to achieve PEO on 304 stainless steel, anodic oxidation (AO) was used as a pretreatment in this study. The coatings were characterised and tested for performance by various methods. The results showed that the PEO-treated coatings had the greatest hardness (530.1 HV), the smallest Icorr (5.0759 × 10-10 A/cm2), and the smallest scratch width (794.05 μm). This study not only solved the problem of applying PEO technology to the surface of 304 stainless steel, but also prepared a coating with excellent friction and corrosion resistance. It provides a new method to improve the properties of 304 stainless steel in the future. Hongkang Pan a, Hailin Lu a, *, Zhengwen Zhang a, Zhanshuai Fan a, Zihan Liu a and Shuangshuang Zhi a, b, *.Investigation on the Investigation on the growth mechanism and properties of AO-PEO com-posite coating on 304 stainless steel prepared by two-step process.Surface and Coatings Technology ( Surface and Coatings Technology ( Impact Factor: 5.4, Chinese Academy of Sciences, Region II).

Fig. 1 Mechanism of PEO coating growth