The present study aims to evaluate the performance of a high-velocity oxy-fuel (HVOF)-sprayed Cr3C2-NiCr (chromium carbide-nickel chromium) coating on a nickel-based superalloy in an actual industrial environment of a coal-fired boiler, with the objective to protect the boiler super-heater and reheater tubes from hot corrosion. The tests were performed in the platen superheater zone of a coal-fired boiler for 1,000 h at 900°C under cyclic conditions. The Cr3C2-NiCr coating imparted the necessary protection to the nickel-based superalloy in the given environment. The dense and flat splat structure of the coating, and the formation of oxides of chromium and nickel and their spinels, might have protected the substrate superalloy from the inward permeation of corrosive species.

Subject
X-ray diffraction, Coatings, Substrates, Metal surfaces, Oxide formation, Chromium, Oxide scales, Chromium oxide, Oxide surfaces, Superalloys, Scale formation, Boilers, Alloys
Keywords:
chromium carbide-nickel chromium coatings, high-velocity oxy-fuel, superalloys
NACE International
2007
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