Hot corrosion behavior of cobalt coated AISI 430 ferritic stainless steel

AISI 430 ferritic stainless steel was coated with cobalt by pack cementation method to investigate the hot corrosion behavior. Coated and uncoated samples were subjected to hot corrosion at 800 °C for 100 hours with a salt mixture consisting of 80 wt.% Na2SO4+20 wt.% NaCl. Coated substrates hot corrosion behavior as a function of corrosion time showed that the formation of spinels containing cobalt (MnCo2O4, CoCr2O4 and CoFe2O4) improves hot corrosion resistance by limiting the inward diffusion destructive ions of oxygen, sulfur and chloride. The weight gain obtained 2.43 mg.cm-2 for uncoated substrates and 1.15 mg.cm-2 for coated substrates after 100 h of hot corrosion at 800 ºC.