The Oxidation Behavior In High-temperature Steam Of Zr₂Al₃C₄ Coating Prepared By Magnetron Sputtering

In 2011,the serious explosion occurred at the Fukushima Daiichi Nuclear Power Plantin in Japan,which triggered an assessment of the safety performance of traditional nuclear fuel cladding materials?zirconium alloys?around the world.The reasons of accident were that the reaction of zirconium alloy with water vapor in a high temperature environment to generate hydrogen.Combined with the current situation,the Zr-UO₂ fuel system all over the world and the lack of practical operating experience of new alternative nuclear materials.Therefore,the surface modification of conventional zirconium alloys will be the most reliable and practical solution to improve the safety performance of zirconium alloys in the nuclear field.The ternary layered compound MAX phase combines the properties of metal and ceramic.In particular,it is expected to play a major role in the field of nuclear materials due to its good resistance to high temperature oxidation and neutron irradiation damage.In this study,Zr₂Al₃C₄ MAX phase was selected as the surface modification material of zirconium alloy.Firstly,Zr₂Al₃C₄ has good resistance to high temperature oxidation and mechanical properties.Secondly,since the limitations of current preparation conditions,there are few studies on Zr-Al-C system coating,and it limits the study of its performance.The preparation of Zr₂Al₃C₄ coating on the surface of zirconium alloy will greatly promote the application of Zr-Al-C coating system in the field of nuclear materials.In this paper,Zr₂Al₃C₄ coating material is selected,and the main conclusions are as follows:?1?The Zr₂Al₃C₄ phase coating was obtained on an Al₂O₃?0001?substrate by magnetron sputtering at room temperature and subsequent annealing.The optimum process parameters of Zr₂Al₃C₄ crystallization phase on the Al₂O₃?0001?substrate were obtained by adjusting the process parameters,such as coating composition,deposition time,annealing temperature and time and so on.?2?The Zr₂Al₃C₄ phase coating was obtained on the zirconium alloy substrates.The Zr₂Al₃C₄ coating was prepared on the zirconium alloy substrates using the best process parameters.It was found that serious diffusion occurred between the zirconium alloy substrate and the Zr-Al-C coating.By adding the Al-C/Si interlayer,the diffusion between the coating and the substrate were successfully slowed down.?3?The Zr₂Al₃C₄ coating has good oxidation resistance in a high temperature steam environment of 1000?-1200?.In the high temperature water vapor environment,ZrO₂ and Al₂O₃ oxide layers are formed on the surface of the coating,which greatly improves the high temperature steam oxidation resistance of the zirconium alloy.And the adhesion of the coating to the substrate is also an important factor affecting the high temperature water vapor oxidation resistance of the coating.