Abstract:
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 Fe
3Al 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 Al
2O
3 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℃.