Effect of diffusion on coating microstructure and
oxidation resistance of aluminizing steel
oxidation resistance of aluminizing steel
(1. Institute of Mechanics, Chinese Academy of
Science, Beijing 100080, P.R.China;
2. Department of Materials Engineering,
Yanshan University , Qinhuangdao 066004, P.R.China;
3. Institute of Corrosion and Protection of Metals,
Chinese Academy of Science, Shenyang 110015, P.R.China)
Science, Beijing 100080, P.R.China;
2. Department of Materials Engineering,
Yanshan University , Qinhuangdao 066004, P.R.China;
3. Institute of Corrosion and Protection of Metals,
Chinese Academy of Science, Shenyang 110015, P.R.China)
Abstract: The effect of diffuse treatment on coating microstructure and oxidation resistance at high-temperature of hot-dip aluminum were studied by means of TEM, SEM and XRD. The results show that, the diffusion temperature has significant effect on structure of coatings and its oxidation resistance. After diffusion at 750℃, the coating consists of thick outer surface layer (Fe2Al5+FeAl2), thin internal layer (FeAl+stripe FeAl2), and its oxidation resistance is poor. After diffusion at 950℃, the outer surface layer is composed of single FeAl2 phase, the internal layer is composed of FeAl phase, and its oxidation resistance declines due to the occurrence of early stage internal oxidation cracks in the coating. After diffusion at 850℃, the outer surface layer becomes thinner and consists of FeAl2+Fe2Al5 (small amount), the internal layer becomes thicker and consists of FeAl+spherical FeAl2，and the spheroidized FeAl2 phase in the internal layer and its existing in FeAl phase steadily improve the oxidation resistance of the coating.
Key words: hot-dip aluminium; dip diffusion aluminum; oxidation resistance at hightemperature; surface coating; microstructure