Corrosion behaviour of iron and nickel aluminide coatings under the synergistic effect of NaCl and water vapour

摘要

Fe-Al and Ni-Al coatings were prepared by aluminizing ferritic-martensitic steels without and with preelectroplating a Ni film, respectively. The corrosion behaviour of two aluminide coatings in marine environment, where high temperature oxidation and corrosion occur under the synergistic effect of solid NaCl and water vapour, were investigated. The results indicated that Ni-Al coatings showed superior corrosion resistance to Fe-Al coatings, the improved performance is mainly due to the beneficial influence of the Ni-plating layer on inhibiting self-sustainable oxychlorination, tungsten outward diffusion and interdiffusion behaviour. The detrimental effects of Fe on breakaway oxidation of Fe-Al coatings are discussed.