Critical Appraisal of Hot Corrosion Behaviour of Burnished HVOF Sprayed WC-CrC-Ni Coatings in Actual Environmental Conditions of Coal Fired Boiler
The cyclic oxidation behavior of uncoated, HVOF sprayed WC-CrC-Ni coating on SA213-T11 substrate and a similar coated specimen followed by burnishing has been studied in coal fired boiler environment. The kinetics of oxidation in bare, coated and burnished-coated specimens was analyzed by Thermogravimetric technique to assess their average loss in thickness loss due to corrosion, loss in scale thickness and the extent of internal corrosion attack. The characterization of tested specimens was done using XRD, SEM and EDAX techniques to analyze the oxidation products of bare, coated and burnished-coated specimens. The burnished WC-CrC-Ni coated SA213-T11specimen has provided the maximum hot corrosion resistance against these environmental conditions. The superior hot corrosion endurance of the burnished-coated specimens along with coated specimens is also ascribed to the establishment of dense chromium oxide layerspecifically above the interface of scale and substrate surface.