Study of Pre-Oxidization Law and Fretting Wear Resistance of CZ2 Alloy Cladding

In the core of pressurized water nuclear reactor, coolant flow-induced vibration of Grid to rod fretting (GTRF) is the dominant factor leading to fuel rod damage. pre-oxidization treatment of zirconium cladding forming a ceramic layer on its surface is the main way to reduce the GTRF wear. In this paper, the growth law of CZ2 alloy cladding pre-oxidization zirconia ceramic layer formed in air was studied. The micro-hardness and elastic modulus of CZ2 alloy cladding and zirconia ceramic layer were measured by in-situ nano-mechanical testing system., while the morphology of these pre-oxidization zirconia ceramic layer were observed by scanning electron microscope. The fretting wear properties of the pre-oxidization zirconia ceramic layer were studied by high temperature and high pressure fretting wear tests. The results show that the pre-oxidization zirconia ceramic layer growth law of CZ2 alloy cladding at 560°C and 600°C is consistent, and the pre-oxidization zirconia ceramic layer are compact and crack-free. The pre-oxidization zirconia ceramic layer can improve the fretting wear resistance of CZ2 alloy cladding at high temperature and high pressure, and the maximum wear depth were reduced by 80%.