Key Quality Indexes and Influencing Factors of Supersonic Spraying Coating for Boiler Water Wall Tubes

Supersonic arc spraying technology was used by a power plant to spray anticorrosion coating on the fire surface of boiler water wall tubes. In order to evaluate the applicability of anticorrosive coating in high temperature and high stress environment of water wall, the coating quality was examined and analyzed by means of chemical composition analysis, microscopic analysis and mechanical property test, combined with actual working conditions and failure cases. The results show that the coating thickness, oxygen content, iron content, porosity and deformation limit are the key indexes to determine the corrosion resistance of coating. Spraying speed, spray wire composition, wire amount and spraying angle are the key influencing factors of these indexes.