Study of the Behavior of Coatings on T-11 Boiler Steet

In the present study, Cr3C2-NiCr and Cr2O3 coatings were deposited on T-11 boiler steel by using the Detonation Gun (D-Gun) thermal spray technique with objective to check the hot corrosion resistance of coatings in air and salt (Na2SO4-60%V2O5) conditions. Uncoated and coated samples were prepared and subjected to study for 50 Cycles at 900oC and 530oC. 1 hour heating and 20 minutes cooling in air was the duration of one cycle. Thermogravimetric study was used for corrosion kinetics of samples. Corrosion products and impact of corrosion on boiler steel samples were analyzed by using SEM/EDS, X-Ray Diffraction techniques. Uncoated boiler steel suffers intense degradation and spalling at high temperature. Cr2O3 coating failed at 900oC and 530oC in air and salt condition and show moderate spalling and crack formation at 530oC in air environment. Cr3C2-NiCr coating show no spalling and crack formation and remain adherent to the substrate. Cr3C2-NiCr coating prove better hot corrosion resistance than other samples considered in this study as revealed by the results.