Different from the simple first-order oxidation behavior of other metal, Mn is prone to complex chain corrosion reaction due to its own polyvalence and Mn²⁺ instability. In this paper, it is found that rare earth salts can be constructed in situ on the electrolytic manganese surface to obtain a composite RE conversion coating with RE³⁺ and Mn²⁺ coexisting. The coating can improve the stability of Mn²⁺, effectively inhibit the bad transformation of Mn²⁺ to higher valence Mn³⁺/Mn⁴⁺, thereby blocking the chain corrosion reaction. Both La and Y conversion coating have good corrosion resistance, stability, corrosion resistance strength and durability, and their i_corr are 1.638 × 10⁻⁶ A/cm² and 2.750 × 10⁻⁶ A/cm², which are reduced by two orders of magnitude. Although the coating performance is not much different, the formation and corrosion process are quite different due to the differences in the RE properties. The comparison of chain corrosion blocking mechanism of electrolytic manganese is of great significance not only to the passivation technology, but also to the application of RE salts in metal passivation.

与其他金属简单的一级氧化行为不同，Mn由于自身的多价性和Mn ^{2+ 的}不稳定性，容易发生复杂的链腐蚀反应。本文发现在电解锰表面原位构建稀土盐可以获得RE ³⁺和Mn ²⁺共存的复合RE转化涂层。该涂层可提高Mn ²⁺的稳定性，有效抑制Mn ²⁺向更高价态Mn ³⁺ /Mn ⁴⁺的不良转变，从而阻断链腐蚀反应。La和Y转化膜均具有良好的耐蚀性、稳定性、耐蚀强度和耐久性，其i _corr分别为1.638×10 ^-6 A/cm ²和2.750×10 ^-6 A/cm ²，降低了两个数量级量级。尽管镀层性能差别不大，但由于稀土特性的差异，其形成和腐蚀过程却有很大差异。电解锰链腐蚀阻断机理的比较，不仅对钝化技术具有重要意义，对稀土盐在金属钝化中的应用也具有重要意义。