Effect of Si content on the microstructure and properties of CrSi coatings for ATF cladding

Microstructure, mechanical properties, corrosion resistance and high-temperature oxidation resistance of four CrSi coatings with different Si content ranging from 0 at% to 67 at% were investigated. With increasing Si content from 11 at% to 67 at%, the main forms of Si exist the coatings were detected to be Cr3Si, Cr5Si3 and CrSi2, respectively. All the CrSi coatings own higher nano-hardness due to the formation of intermetallic. For Si content <= 33 at%, the CrSi coatings showed good corrosion resistance in static pure water of high temperature and pressure. However, the higher Si content (67 at%) led to the dissolution of Si in the form of [Si(OH)]4, as well as insufficient Cr to form a continuous Cr2O3 layer. The high-temperature oxidation tests showed that the coating with 11 at% Si content exhibited the best oxidation resistance than other coatings, due to the formation of outermost Cr2O3 layer, stable Cr3Si phase and inner Zr2Si. Our study indicates that the coating with 11 at% Si content displays good comprehensive properties and could be used as a candidate material for ATF coatings.