Effect of Si content on the 1200 - 1300°C steam oxidation and 360°C/18.6MPa autoclave water environmental resistance of Cr-Si coatings on Zry-4

Abstract

In this study, we applied magnetron sputtering to deposit four Cr-Si coatings on Zry-4, with varying Si content ranging from 0.03 to 0.22 at.%. The main objective was to investigate the influence of Si content on the mechanical properties, steam oxidation resistance at 1200 - 1300 °C, and corrosion resistance in a 360 °C/18.6 MPa autoclave water environment. As the Si content increased, we observed a corresponding enhancement in both the mechanical properties and oxidation resistance of the coating. Notably, at 1300 °C, the oxidation resistance of Cr-Si coated Zry-4 demonstrated improvement when the Si content reached or exceeded 14 at.%, attributed to the formation of an in-situ Zr2Si layer at the coating/substrate interface. However, in the 360 °C/18.6 MPa autoclave water environment, we noted a decrease in the corrosion resistance of the Cr-Si coatings with increasing Si content. This phenomenon was ascribed to the selective dissolution of Si. Moreover, when the Si content surpassed 14 at.%, the surface Cr2O3 underwent a transformation, resulting in the formation of three non-protective sublayers: an amorphous layer, a nanocrystalline layer, and a coarse crystalline layer. These findings provide valuable insights into the overall performance, as well as the advantages and disadvantages, of Cr-Si coatings on Zry-4.