应用X射线衍射仪(X-ray diffraction, XRD)、扫描电子显微镜(Scanning electron microscope, SEM)、能谱仪(Energy dispersive spectrometer, EDS)和电子探针显微分析(Electron probe X-ray micro-analyser, EMPA)等分析方法研究预涂覆Na2SO4-25%NaCl盐膜的HR3C在650 ℃、750 ℃的高温腐蚀行为。结果表明：HR3C在650 ℃和750 ℃的腐蚀动力学曲线呈“抛物线”趋势递增;腐蚀产物由表向里依次是结构疏松的Fe2O3与相对致密的Cr2O3的氧化层、尖晶石结构的复杂氧化物以及由少量Fe/Ni硫化物和孔隙组成的腐蚀影响区;提高腐蚀温度或延长腐蚀时间,氧化膜明显增厚,与基体结合程度变差甚至剥离,腐蚀影响区孔隙密度增大,深度增加。分析认为：预涂覆Na2SO4-25%NaCl盐膜的HR3C的高温腐蚀是氧化、硫化与氯化共同作用的结果。腐蚀初期发生高温氧化,合金表面形成具有保护性作用的氧化层;氯化反应促进了混合盐膜的熔融与挥发性物质的形成,破坏了氧化层的致密性,加速了腐蚀反应的发生;硫化作用促使合金发生内硫化。
李萍
,
秦鹏
,
赵杰
,
李廷举
,
庞胜娇
. 预涂覆Na2SO4-25%NaCl盐膜的HR3C钢的高温腐蚀行为[J]. 机械工程学报, 2016
, 52(8)
: 104
-111
.
DOI: 10.3901/JME.2016.08.104
The high-temperature corrosion behaviors of HR3C pre-coated Na2SO4-25%NaCl salt film at 650 ℃ and 750 ℃ are investigated by means of X-ray diffraction(XRD), scanning electron microscope(SEM), energy dispersive spectrometer(EDS) and electron probe X-ray micro-analyser(EMPA). The results show that the corrosion kinetic curves of HR3C at 650 ℃ and 750 ℃ reveal the parabolic growth law. The corrosion products are mainly composed of Cr/Fe oxides, minor compound oxides with spinals structure as well as (Fe,Ni)xSy. Improving the corrosion temperature or prolonging the corrosion time, the oxide films in thickness increase significantly and the adjacent with the substrate is worse and seriously peeled off the surface, moreover, the pore densities among the corrosion affected zone (the interface between the oxide films and the matrix) increase. It is concluded that the high temperature corrosion of HR3C pre-coated Na2SO4-25%NaCl salt film is dominated by the interaction of oxidation, sulfidation and chlorination and Cl- is more detrimental than SO42- to HR3C. In the early stage of corrosion, high temperature oxidation occurred on the surface of the alloy and formed the oxide layers which had protective effect. The chlorination reaction promoted the fluxing of the mixed salt film as well as the formation of the volatile products, which destroyed the compact oxide layers. In addition, the vulcanization accelerated the occurrence of the alloy sulfide.
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