铝化物涂层改性Super304H钢在模拟锅炉煤灰/气环境中的腐蚀行为

摘要

利用粉末包埋法在Super304H钢表面制备了铝化物涂层,在模拟锅炉煤灰/气环境中对涂层改性前后的Super304H钢和HR3C钢分别进行了650,750 ℃腐蚀试验,对比分析了其腐蚀行为及腐蚀机制.结果表明:铝化物涂层主要由FeAl和Fe3Al相组成;在650 ℃腐蚀500 h后,涂层改性前Super304H钢表面氧化膜出现大面积剥落,而涂层改性后的钢表面则形成了均匀致密的Al2O3膜;在750 ℃腐蚀时,涂层改性前Super304H钢在腐蚀200 h后其表面氧化层完全剥落,而涂层改性后的钢经500 h腐蚀后,表面氧化膜剥落较改性前的轻,比650 ℃时的严重;铝化物涂层提高了Super304H钢的耐腐蚀性能,但高铬含量的HR3C钢在650 ℃和750 ℃下均表现出更好的耐腐蚀性能.%Aluminide coating was prepared on surface of super304H steel using pack cementation method.Then the corrosion tests at 650 ℃ and 750 ℃ were conducted on the Super304H steel before and after coating modification and on the HR3C steel in simulated boiler coal-ash/gas environment, respectively.The corrosion behavior and corrosion mechanism were analyzed and compared.The results show that the coating was composed of FeAl and Fe3Al phases.After corrosion at 650 ℃ for 500 h, the oxidation film on the surface of unmodified Super304H steel was spalled with a large area, while an uniform and dense Al2O3 film was formed on the surface of coating modified Super304H steel.The surface oxidation film of unmodified Super304H steel was spalled completely after corrosion at 750 ℃ for 200 h, however,the spallation of surface oxidation film of coating modified steel after corrosion at 750 ℃ for 500 h was slighter than that of unmodified steel while more serious than that at 650 ℃.The aluminide coating improved the corrosion resistance of Super304H steel significantly.But the HR3C steel with high Cr content had a relatively good corrosion resistance at 650 ℃ and 750 ℃.