Enhanced cyclic oxidation resistance of Metcoloy II coated ASTM A53 Grade B steel by electric arc thermal spray

This study evaluates the enhanced cyclic oxidation resistance of Metcoloy II coatings applied to ASTM A53 Grade B steel substrates using electric arc thermal spray, across temperatures ranging from 500 °C to 700 °C. The research identifies distinct performance differences between coated and uncoated samples under cyclic oxidation conditions. Initially, both sample types exhibited mass increases due to oxide formation. However, uncoated samples developed non-protective iron oxides, while Metcoloy II coatings formed a protective layer of chromium and nickel oxides. During 500 oxidation cycles at 500 °C, uncoated samples showed a rapid mass increase, indicative of accelerated oxidation, whereas Metcoloy II coatings experienced a controlled mass gain, reflecting effective protection by chromium and aluminum oxides. At 700 °C, the mass variation trends were similar for both types initially; however, uncoated samples suffered significant mass loss due to iron oxide volatilization, emphasizing their susceptibility. Conversely, Metcoloy II coatings exhibited a reduced but steady mass increase, indicating their resilience under high-temperature conditions. Microstructural analysis confirmed the presence of a protective oxide layer in the coated samples, which is essential for reducing substrate oxidation. Although challenges such as coating detachment and thinning were observed, particularly at higher temperatures, Metcoloy II coatings maintained their protective role. This study highlights the coating's effectiveness in extending the lifespan of steel substrates subjected to cyclic oxidation, providing valuable insights for optimizing protective coatings in demanding industrial applications and advancing material science strategies for enhanced durability.