Si-Mo-MODIFIED ALUMINIDE SLURRY COATING FOR HIGH TEMPERATURE PROTECTION OF AUSTENITIC STAINLESS STEEL
Slurry aluminide coating is considered one of the most excellent coating materials to enhance hot corrosion resistance for high temperature applications. In this research, Si-, Mo- and Si-Mo-modified slurry aluminide coatings were prepared on 304 stainless steel at 650 ºC for 4 h and 6 h. The influence of Si, Mo and Si-Mo additions into the coatings was studied by comparing the coating properties at different aluminizing time. The physical, chemical and mechanical properties of the aluminide coatings were characterized using the Vickers microhardness test, FESEM, EDX and XRD. The addition of Si and Mo into the coating slightly changes the coating behaviour of the alloy. A multi-layered coating structure was observed after the aluminizing for all coating samples. A dense and continuous inner layer made up of FeAl-base intermetallic is believed to improve the corrosion resistance of the stainless steel. The hardness value (HV) increased with an increasing in aluminizing time for Mo- and Si-modified aluminide coatings. In contrast, Si-Mo-modified aluminide coating showed a decreased in hardness value (HV) due to the formation of multi-crack and porous coating structures. A modified slurry aluminide coatings on 304 stainless steel could be considered as a viable potential for high temperature application.