Corrosion performance of plasma-sprayed cast iron coatings on aluminum alloy for automotive components

Corrosion behaviour of coatings sprayed with water-atomized (WA), cast iron powder were investigated by surface analyses and electrochemical methods, such as potentiodynamic polarization test and electrochemical impedance spectroscopy (EIS) in deaerated 0.5 M H2SO4 solution. WA cast iron powders of Fe–3.75C–3.60Si–3.93Al (wt.%) were deposited onto an aluminum alloy (AA383 alloy) substrate by atmospheric DC plasma spraying. Four types of samples were prepared including cast iron liner and aluminum alloy substrate. C1 coating was produced by using as-received WA cast iron powders without graphite and C2 coating by using pre-annealing cast iron powder containing graphite structure. The results of the electrochemical tests indicated that the C2 coating had greater corrosion-resistant properties than the C1 coating, which could be attributed to its lower porosity, higher protective efficiency, and increased packing factor.