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. C-1 coating was produced by using as-received WA cast iron powders without graphite and C-2 coating by using pre-annealing cast iron powder containing graphite structure. The results of the electrochemical tests indicated that the C-2 coating had greater corrosion-resistant properties than the C-1 coating, which could be attributed to its lower porosity, higher protective efficiency, and increased packing factor. (c) 2005 Elsevier B.V All rights reserved