EROSION-CORROSION OF THERMAL SPRAYED COATINGS IN FBC BOILERS

Varieties of bed ash and fly ash were retrieved from operating fluidiz ed bed combustor (FBC) boilers firing different fuels in North America and Europe. Using these ashes, the relative erosion-corrosion resista nces of HVOF Cr3C2-NiCr coating and several other thermal sprayed coat ings were determined in an elevated temperature blast nozzle erosion t ester. Test conditions attempted to simulate erosive conditions found at the refractory-waterwall interface and in the convection pass regio n in tubular heat exchangers of FBC boilers. Erosion-corrosion (E-C) w astage mechanisms of the structural metals (AISI 1018, ASTM SA213-T22) were discussed and compared with the E-C wastage of HVOF Cr3C2-NiCr c ermet coatings. The relatively different erosivities of ashes retrieve d from North America and from Europe were also discussed.