BEHAVIOUR OF Cr3C2–NiCr & Al2O3-40%TiO2 COATED SS-316 BOILER STEEL WITH RESPECT TO LOW TEMPERATURE HOT CORROSION AND HIGH TEMPERATURE HOT CORROSION by Pawandeep Singh
Abstract
Hot corrosion is the major problem occur in boilers and its components. It happens when temperature
range of 650-9000C is used for heating of metals in sulphate environment, due to the reaction between sulphur compounds and sodium chloride in gas phase around the metals then hot corrosion takes place. Principal agent which causes the hot corrosion is molten sodium sulphate. In the present study SS-316 boiler steel has been investigated for low temperature and high temperature hot corrosion with respect to molten salt environment and oxidation behaviour. D-Gun spray process was used for coating of SS-316 boiler steel with Cr3C2–NiCr & Al2O3-40%TiO2 powders. Cr3C2– NiCr & Al2O3-40%TiO2 coated specimens were subjected to low temperature hot corrosion at 6500C and high temperature hot corrosion at 9000C in the presence of Na2SO4 molten salt environment for 75 cycles. Coating was analyzed by Scanning electron microscope (SEM), Energy-dispersive X-ray spectroscopy (EDAX) and X-ray powder diffraction (XRD), For both low and high temperature hot corrosion Cr3C2–NiCr coating has shown better oxidation resistance than Al2O3-40%TiO2 coating. Weight change measurements indicated higher weight gain of Al2O3-40%TiO2 coated sample than Cr3C2–NiCr coated sample.
