研究了Fe-8Cr, Fe-12Cr和Fe-18Cr合金在700℃含氯和两种硫含量还原性气氛中的腐蚀行为. 气氛中H2S含量增加导致合金发生加速腐蚀, 尤其造成Fe-18Cr合金表面氧化铬膜退化. 合金的加速腐蚀与膜中生成的硫化物和氯化物密切相关. 合金的腐蚀速率随其Cr含量的升高而降低. 通过计算气氛中平衡时的氯势、氧势、硫势预测了合金与气氛可能发生的反应, 并解释了腐蚀机制.
The corrosion behavior of three Fe-Cr alloys has been examined at 700oC in reducing atmospheres containing constant HCl and two different levels of H2S. Except for Fe-18Cr in the low-H2S gas mixture, in all cases the scales consisted of an outermost porous layer of iron oxides overlaying an inner layer of a mixture of the Fe and Cr oxides and the Fe-Cr spinel plus a zone of internal attack rich in oxygen with little sulfur. An increase of the H2S level in gas mixtures produced an accelerated corrosion for all Fe-Cr alloys, particular for Fe-18Cr. An increase of the Cr content induced the decrease of the corrosion rate in two gas mixtures. The accelerated corrosion induced by sulfur and chlorine is mainly due to the formation of sulfides and chlorides in the scales. The equilibrium partial pressures of chlorine, oxygen and sulfur of the mixed gases were calculated to estimate the possible reactions between the alloy components with the multi-reactant atmosphere and to interpret their corrosion behaviors.
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