BEHAVIOUR OF THERMAL SPRAYED COATINGS ON BOILER TUBE STEEL IN ACTUAL INDUSTRIAL ENVIRONMENT
Gursham Lal; Hazoor Singh Sidhu; Buta Singh Sidhu
National Conference on Advancements and Futuristic Trends in Mechanical and Materials Engineering (AFTMME 2010)
Abstract
The failure of boiler tube steel due to erosive-corrosive atmosphere is a serious problem in coal fired power plants and due to this thermal efficiency of plant is reduced. The thermal spray coatings enhance the degradation resistance of boiler tube steel. The four types of alloy powders i. e. NiCr, Cr3C2 –NiCr, WC-Co, Stellite-6 are used to spray on the SA210GrA1 boiler tube steel by High Velocity Oxy Fuel(HVOF) coating technique. The uncoated and coated steel samples were hanged in the platen super heater zone of coal fired boiler at 9000C for six cycles each of duration168 hours. The eroded-corroded samples of coated as well as uncoated steel are analyzed for corrosion products by XRD, SEM/EDAX and EPMA techniques. It has found that the uncoated steel got totally oxidized due to formation of un protective Fe2O3. The rate of degradation was lowest in case of Cr3C2-NiCr coated steel and its degradation resistance is due to the formation of protective oxides like Cr2O3,, NiCr2O4 etc. However the WC-Co coated steel was less protective among the coated steels.
Key words: Erosion, Corrosion, HVOF coatings
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