超临界锅炉用材料的高温腐蚀研究进展

合金材料的耐高温腐蚀性能研究在先进超临界火电机组的发展中占有相当重要的地位,随着锅炉参数的提高,高温腐蚀逐渐成为合金材料使用寿命的主要制约因素。从三种主要的超临界锅炉合金材料出发(铁素体耐热钢、奥氏体耐热钢以及镍基高温合金),综述了常用的锅炉用高温合金材料及其高温腐蚀研究,包括在不同环境中的腐蚀,如SO_2气氛、KCl蒸汽、Na_2SO_4盐膜以及NaCl盐膜对高温腐蚀的影响;合金元素以及锅炉温度对高温腐蚀的影响。通过对腐蚀产物形貌、结构及元素分布的总结,对已有的研究成果进行了分析比较,发现大多数合金的腐蚀产物出现了分层现象,并且腐蚀过程中氧化-硫化过程交替进行,导致S元素的侵入以及腐蚀产物层的松动。讨论了腐蚀过程从萌生到加速腐蚀的历程机理,总结了锅炉不同高温腐蚀类型(焦硫酸盐腐蚀、复合硫酸盐腐蚀及氯化物腐蚀)。最后展望了未来高温腐蚀研究在超临界锅炉领域的发展方向。

Research Progress on the High Temperature Corrosion of Supercritical Boiler Materials

Study on high temperature corrosion resistance of alloy materials occupies an important position in the development of advanced supercritical thermal power unit. With the increase of boiler temperature, high temperature corrosion is increasingly a major constraint on service life of alloy materials. Based on the three major high temperature alloy materials of supercritical boiler (heat-resistant ferritic steel, heat-resistant austenite steel, nickel-base superalloy), the common materials used in supercritical boiler and corresponding studies on high temperature corrosion were reviewed. The effects of environment (SO2 atmosphere, KCl vapor, Na2SO4 melt salt, NaCl melt salt), alloy element and boiler temperature on high temperature corrosion were included as well. Previous study results were analyzed and compared by summarizing morphology, construction and elements distribution of corrosion products. As a result, most alloy corrosion products were found to be subject to delamination phenomenon, and the alternate process of oxidation and sulfuration led to the penetration of S element and porous structure looseness of corrosion product. The corrosion mechanisms from generation to accelerated corrosion were discussed, and the different types of high temperature corrosion were categorized (pyrosulfate corrosion, composite sulfate corrosion and chloride corrosion). Finally, the development trend of studies on the high temperature corrosion in supercritical boiler was forecasted.