超超临界锅炉水冷壁涂层失效分析

Failure Analysis of Water Wall Coating for Ultra⁃supercritical Boiler

超低排放锅炉的低氮燃烧使向火侧水冷壁高温腐蚀严重,目前部分发电企业采用水冷壁防腐涂层提高其服役环境下的寿命,针对某发电企业水冷壁涂层脱落进行探究,分析水冷壁的腐蚀机理及涂层的失效原因,结果表明:水冷壁涂层大规模脱落的直接原因为S元素通过涂层孔隙穿透,对涂层进行腐蚀导致涂层与基体结合力下降,产生大量微裂纹,微裂纹在热应力与S腐蚀作用下不断扩展延伸,最终导致涂层大面积脱落失效。

low nitrogen combustion causes serious high temperature corrosion of water wall on fire side.At present,some power plants use wa⁃ter wall anti⁃corrosion coating to improve their service life.A power plant water wall coating off to explore,analysis of water wall corrosion mechanism and coating failure reasons.The results show that:The direct reason for the large⁃scale peeling off of water wall coating is that s el⁃ement penetrates through the pores of the coating and corrodes the coating,resulting in the decrease of the adhesion between the coating and the substrate and the generation of a large number of microcracks.The microcracks continue to expand and extend under the action of thermal stress and s corrosion,which eventually leads to the large⁃scale peeling off of the coating.