Sulphidation Resistance of Nickel-Aluminide Coatings on Austinitic Stainless Steel AISI 321

Nickel aluminde coatings were performed on austinitic stainless steel base alloy (321AISI) by packcementation method. Nickel was used as electrodeposition coating before aluminization. Hot corrosion (Sulphidation) behavior of the coatings after exposure in molten salt (Na2SO4) at (884 C) were studied under cyclic condition. The Al-rich intermetallic compound was very effective in reducing the corrosion rate in molten salt, while (Ni) or Ni-rich and Fe-rich intermetallic compounds were less resistances. Uncoated stainless steel reveals very poor resistance to Sulphidation in molten salt environment with sever spallation of the protective oxide scale.