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研究了 Fe—Cr 合金在有 K2SO_4-Na_2SO_4盐膜存在时的低温热腐蚀行为。测定涂盐的 Fe-Cr合金于 O_2-0.1、0.5和1.0%(SO_2+SO_3)气氛中在560～750℃温度区间腐蚀动力学曲线,并对腐蚀产物进行物理观察和化学分析。结果表明,当有 K_2SO_4-Na2SO_4盐膜存在时,铬含量低于某一临界值的 Fe—Cr 合金会发生低温热腐蚀,这归因于 K—Na—Fe 三元低熔点复合硫酸盐的形成。Fe~(3+)被认为参与了电化学阴极反应,Fe~(3+)/Fe~(2+)在熔盐层中的相对迁移将气相中 O_2和SO_3的主要还原反应移至熔盐/气相交界面进行,从而导致快速热腐蚀。铬是减轻和抑制低温热腐蚀的有效元素。
The low temperature hot corrosion behavior of Fe-Cr alloy in the presence of K2SO_4-Na_2SO_4 salt film was studied. The corrosion kinetics curves of the coated salt-coated Fe-Cr alloy in the temperature range of 560-750 ℃ in O_2-0.1, 0.5 and 1.0% (SO_2 + SO_3) atmosphere were measured and the corrosion products were observed and analyzed chemically. The results show that when there is K_2SO_4-Na2SO_4 salt film, low-temperature hot corrosion occurs in the Fe-Cr alloy with the chromium content below a certain critical value, which is attributed to the formation of K-Na-Fe ternary low melting point composite sulfate . Fe ~ (3+) is considered to participate in the electrochemical cathode reaction. The relative migration of Fe ~ (3 +) / Fe ~ (2+) in the molten salt layer shifts the major reductions of O_2 and SO_3 in the gas phase to molten salts / Gas interface, resulting in rapid thermal corrosion. Chromium is to reduce and inhibit low-temperature hot corrosion of the effective elements.