Evaluation of characteristics and behavior of cold sprayed Ni–20Cr coating at elevated temperature in waste incinerator plant

• The Ni–20Cr is cold sprayed on substrate grade similar to Nimonic 75 alloy.
• This coating is tested in chlorine based corrosive waste incinerator plant.
• The dense coating is able to provide hot corrosion protection to the substrate.
• The coating lowers the corrosion rate of substrate from 1.042 to 0.594 (mm/year).

Hot corrosion failure of components in power plant industry, like waste incinerators and WTE plants, is still a serious issue. The chlorine present in the plant environment acts as a catalyst and thereby, accelerates the corrosion reactions through the ‘Active oxidation’ phenomenon, which consists of chloridation, evaporation and re-oxidation. In this study, efforts were made to study the hot corrosive behavior of 80%Ni–20%Cr coating in the real service medical waste incinerator environment at 900 °C. The coating was deposited on a superalloy substrate by cold spraying. The coating performance has been characterized using the combined techniques of XRD, SEM/EDX and elemental X-ray analysis. The chlorine based incinerator environment is found to be so aggressive that corrosive species are able to penetrate through the uncoated superalloy. However, the cold sprayed coating is able to protect the superalloy from the highly corrosive degrading species present in this environment.