“…However, the wastewater in this corresponding process containing hexavalent chromium and phosphate enrichment, results in serious water pollution [12], hazarding human health, and severely going against the requirements of environmental protection. Therefore, researchers have been exploring the various of environmentally friendly passivation films with excellent anti-corrosion effects, such as molybdate [13,14], silicate [15,16], titanate [17,18], vanadate [12,19,20], rare earth salt [21][22][23] and so on. For instance, Qiu et al [18] successfully prepared a titanium passivation film on the surface of electrolytic manganese by adjusting the conditions of the titanium solution, and its corrosion resistance is better than that of the Cr coating.…”