Effect of Si content on the oxidation behavior of CoCrWSi coatings at 900 °C

Abstract

In this study, CoCrWSi coatings with different Si contents were prepared via high-velocity oxygen fuel spraying, and the effect of Si content on their high-temperature oxidation resistance in air was studied at 900 °C. The microstructures and chemical compositions of oxide scales were characterized through scanning electron microscopy, electron probe microanalysis, and X-ray diffraction. The results revealed that the oxidation resistance of the produced CoCrWSi coatings gradually increased with increasing Si content. Moreover, the beneficial effects of Si content on the oxidation resistance were discussed in terms of Si depletion. The addition of Si prevented the outward diffusion of Cr atoms, and inhibited internal oxidation, while the depth of internal oxidation varied significantly with the oxidation time.