Studies on the Behavior of Ni-20Cr Plasma Spray Coatings Applied on Boiler Tube Steels in Molten Salt (Na₂SO₄-60%V₂O₅) Environment at 900°C

Ni-20Cr coatings were obtained on the boiler tube steels through a plasma spray process. Ni-Cr-Al-Y was used as a bond coat before the application of Ni-Cr coatings. The coating was characterized and the hot corrosion behavior was evaluated after exposure to molten salt (Na₂SO₄-60%V₂O₅) at 900°C under cyclic conditions. The coating was very effective in decreasing the hot corrosion rate in molten salt at 900°C in the case of the ASTM-SA210-Grade A1 and ASTM-SA213-T-11 types of steels. The coating was found to be less effective in the case of the ASTM-SA213-T-22 type of steel. The uncoated ASTM-SA213-T-22 type of steel had shown very poor resistance to hot corrosion in a molten salt environment and also indicated the spalling of oxide scale.