Characterisation of nicr flame and plasma sprayed coatings for use in high temperature regions of boilers

Abstract

Nickel–chromium coatings have been plasma sprayed onto a stainless steel surface in order to protect it from the high temperature and erosive conditions encountered in power plant boilers. Microstructure, porosity, and microhardness of the coatings have been studied. High temperature oxidation behaviour was studied in an atmosphere similar to service conditions used in power plant, and thermal fatigue tests were performed in an experimental combustion chamber. Finally, adhesion between the steel substrate and NiCr coating was evaluated by means of tensile tests. The results obtained are discussed with particular reference to the evolution of microstructure owing to thermal effects and coating deposition method.