Paper Title
Development of Coating for High Temperature Corrosive Applications

Abstract
In this study a wear and corrosion resistant Ni-Cr based coating composition is cold sprayed on superalloy for further testing in high temperature applications. Coating density (porosity), micro-hardness and wear properties are studied by various characterization techniques. This newly fabricated coating found to be wear resistant, smooth and dense with porosity <1. Cold sprayed coating particles remained in solid-state as observed in micrographs, which is a unique property of this coating technology as compared to other coating techniques of thermal spray family. The observed microstructure and coating-substrate combination is found to be suitable for high temperature applications such boiler tubes, turbines and incinerators. There is need to work on various preventive corrosion methods to enhance the material life of various components in the industry. Prevention of corrosion will result in increase the plant efficiency and this is also related to environmental issues. This study is planned primarily on this issue with new combination of substrate and coating developed by cold sprayed technique is tested for highly corrosive environment. Corrosion resistant coating Cr3C2-NiCr is tested in highly corrosive chlorine containing environment at 900 oC under cyclic conditions. Cold sprayed coating is dense (porosity less than 1), hard (average 899 HV) and smooth with surface roughness 5.05 μm. Triobology tests on Pin-on-Disc machine also shows better performance of the coating in wear conditions. Coating microstructure developed for this environment has shown corrosion protective ability in chlorine containing. Coating performance is tested by weight change during corrosive exposure and it is found that coating performance is better as compared to bare substrate alloy. Weight gain change of coating shows parabolic behavior as against the bare alloy. This coating microstructure is suggested for applications in highly erosive-corrosive high temperature conditions upto temperature of 900 oC. Keywords: Corrosion, Coating, Cold Spray, Power Plant