Hot Corrosion Studies on HVOF Coated Alloy A-286 in Molten Salt Environment

The corrosion resistance Cr3C2-25%NiCr and Ni-20%Cr coatings were deposited on the alloy A-286 by high-velocity oxy-fuel (HVOF) coating, and the high-temperature corrosion features were evaluated at 700 and 850°C in Na2SO4-5%NaCl-7.5%NaVO3 atmosphere. Deposited coatings are dense and well-adherent to the substrate. A scanning electron microscope (SEM) is used to analyze the structure of the corroded samples. Results showed that Cr3C2 -25%NiCr coating provides better resistance to corrosion at 700°C, which is attributed to the protective Cr2O3 development. The coated metal was exposed at 850°C, and a higher corrosion rate was observed compared to 700°C, indicating that the temperature influenced the oxidation rate. The coating failure (crack) was noticed on the Cr3C2-25%NiCr coated surface when exposed at 850°C, and no damages are in the Ni-20%Cr coating.