Corrosion behaviour of aluminide coatings on Ti-based alloy in the marine environment at high temperature

Ni-Al aluminide coating was deposited by electroplating of Ni and subsequent aluminisation while Ti-Al aluminide coating was deposited by aluminisation directly on Ti-based alloy. The corrosion performance of two coated samples with uncoated sample in marine environment in the presence of NaCl and water vapour at 700 °C were studied. Ni-Al coated sample showed the best corrosion resistance. Ti-Al coated sample showed severer corrosion in marine environment compared with that in static air due to self-sustainable oxychlorination process. The detrimental effect of Ti and beneficial effect of Ni-plating on self-sustainable oxychlorination in marine environment are discussed.