Research on Properties of SiC Coating on Zirconium Alloy Clad Tube Surface Prepared by PECVD Method

SiC is a potential coating material for accident resistant fuel cladding. In order to avoid high-temperature failure of the strength of zirconium alloy clad tube, it is necessary to develop low-temperature preparation technology for SiC coating. Plasma enhanced chemical vapor deposition（PECVD） method was used to prepare uniform and dense SiC coating on the surface of zirconium alloy clad tube, using methylsilane as the only reaction gas source, and the deposition temperature was lower than the final annealing temperature of zirconium alloy（-600 ℃）. The phase composition, micromorphology,bonding strength and mechanical properties of the SiC coating on zirconium alloy clad tube were analyzed and tested using X-ray diffractometer, Raman spectrometer, scanning electron microscope, atomic force microscope, adhesion scratch tester and universal testing machine. The results show that compared with conventional chemical vapor deposition（CVD）preparation technique, the SiC coating prepared by PECVD method has a microcrystalline structure, and the coating is uniform, dense, smooth and flat,which has excellent bonding with the zirconium alloy clad tube substrate. Compared to the CVD-SiC coating, the axial tensile strength has been improved by about 110 MPa, with significant performance advantages.