Slurry sprayed glass-ceramic coating for boiler tubes and its high temperature performance

Industrial boilers operate in extreme environments and are prone to degradation caused by high temperature oxidation, corrosion, and erosion. Protective coatings provide boiler components with protection to prolong their operation lifetime. Thus, a glass-ceramic coating has been developed using a slurry spray technique on carbon steel AS/NZS 3678 substrates. Microstructure, mechanical characteristics, and high temperature performance of the coating were investigated. The coating composed of chemically inert oxide ceramics dispersed in a glassy silicate binder matrix. The adhesion strength of the coating was 10.79 +/- 0.86 MPa. Coating mass loss after abrasion test was 0.013 % of the tested specimen. The coating withstood at least 75 air quenched thermal shock cycles from 800 degrees C to the room temperature without any visible spallation and cracks. The coating mostly remained undamaged after cyclic oxidation at 800 degrees C for 10 cycles. However, minor iron oxide formation was observed, specifically, in relatively thin sections of the coating. The oxidation resistance of the boiler steel has been improved with the developed coating. The linear oxidation rate constant of the boiler steel has been statistically reduced from 6.90 x 10(-4) mg cm(-2) s(-1) to 1.95 x 10(-4) mg cm(-2) s(-1) for coated steel (p = 0.007). The developed slurry spray glass-ceramic coating is a potential candidate for boiler environments.