Hot corrosion behaviour of HVOF-sprayed 93(WC-Cr₃C₂)-7Ni and 83WC-17Co coatings on boiler tube steel in coal fired boiler

Abstract

The present work was an attempt to find the hot corrosion behaviour of high velocity oxy-fuel-sprayed 93(WC-Cr₃C₂)-7Ni and 83WC-17Co coatings on boiler steel alloys, ASME SA213-T22 and ASME SA213-T91 in coal fired boiler environment in superheater zone. The coated and uncoated specimens were exposed to actual boiler environment for 10 cycles. Each cycle consisted of 100 h heating followed by 1 h cooling at ambient conditions. The thermogravimetric technique was used to establish the kinetics of corrosion. X-ray diffraction, scanning electron microscopy/energy dispersive spectroscopy techniques were used to analyse corrosion products. The hot corrosion resistance of 93(WC-Cr₃C₂)-7Ni-coated ASME SA213-T91 specimens was better among all coated specimens.

Keywords:

• Corrosion
• boiler steel
• degradation
• HVOF
• coal fired boilers