کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
5362611 | 1503686 | 2013 | 7 صفحه PDF | دانلود رایگان |
- Fe-Al phases formed in the steels after hot-dipping in pure aluminum are the same.
- Chromium retarded the interdiffusion between steels and pure aluminum bath.
- Chromium caused the transformation from Ï5(H)-Al7Fe2Si into Ï5(C)-Al7(Fe,Cr)2Si.
- Formation of Ï5(C)-Al7(Fe,Cr)2Si enhanced the steels/Al-10Â wt.% Si bath interdiffusion.
Cr-Mo steels with different chromium contents were coated by hot-dipping into molten baths containing pure aluminum and Al-10Â wt.% Si for 180Â s. The effect of chromium content in the steels on the formation of the intermetallic phases in the aluminide coatings was studied. The results show that all the aluminide coatings can be distinguished into an outer pure aluminum or Al-Si topcoat and an inner intermetallic layer. The intermetallic layers, resulting from the steels hot-dipped in pure aluminum, have the same phase constitution, an outer minor FeAl3 and an inner major Fe2Al5. In the aluminide coatings on the steels with 0 and 2.25Â wt.% chromium after hot-dipping in Al-10Â wt.% Si, the intermetallic layers were composed of an outer layer of Ï5(H)-Al7(Fe,Cr)2Si and an inner one of FeAl3/Ï1-(Al,Si)5Fe3/Fe2Al5, while a small amount of polyhedral Ï5(H)-Al7(Fe,Cr)2Si and plate-shaped Ï6-Al4FeSi were observed in the Al-Si topcoats. In the aluminide coatings on the steels with 5 and 9Â wt.% chromium after hot-dipping in Al-10Â wt.% Si, the intermetallic layers were composed of only a Ï5(H)-Al7(Fe,Cr)2Si phase. A large amount of scattered granular Ï5(C)-Al7(Fe,Cr)2Si and a small amount of plate-shaped Ï4-Al3FeSi2 and Ï6-Al4FeSi were also found in the Al-Si topcoats. When the chromium content reached 5Â wt.%, the amount of steel, which dissolved when samples were hot-dipped in Al-10Â wt.% Si, increased. Also, the rate of dissolving went up as chromium content went up. The increase of dissolution is because the interdiffusion between steels and Al-10Â wt.% Si bath was enhanced by the formation of scattered granular Ï5(C)-Al7(Fe,Cr)2Si, which was stabilized by chromium.
Journal: Applied Surface Science - Volume 277, 15 July 2013, Pages 139-145