The FeCr-Based Coating by On-Site Twin-Wire Arc Spraying for Proactive Maintenance of Power Plant Components

Abstract

There is high demand for refurbishment of damaged mechanical components in power plants. Twin-wire arc spraying (TWAS) is promising for on-site proactive maintenance. In this paper, FeCr-based coating was prepared on AISI 1020 carbon steel substrate by TWAS. The coating microstructure was characterized in terms of porosity, oxides and constituent phases. The wear behavior of the coating was evaluated by ball-on-disk wear test at both room temperature (RT) and tube service temperature of 300 °C. The results show that the coating is characterized with composite-like structure of oxide boundaries and FeCr solid solution, with hard phase of borides embedded within FeCr phase, resulting an average microhardness of 10.80 GPa. Tested at RT and 300 °C, the weight loss of the coating indicates much better wear resistance than substrate steel. The morphology of the wear scars demonstrates that the wear mechanism of the coating transformed from furrow and fracture spalling at RT to adhesive and abrasive wear at high temperature. The high hardness and low oxidation rate of the coating contribute to excellent wear resistant. The FeCr-based coating by on-site TWAS has been successfully applied on boiler tubes, large-sized blades of slurry pumps and various fans.