The Study On Preparation And Corrosion Properties Of Fecral Coatings By Magnetron Sputtering

Nuclear power is not only continuous and stable,but also more economical and efficient compared with wind power and hydropower.Since the Fukushima nuclear accident in 2011,nuclear energy research and development have been focusing on improving the capacity of nuclear reactor accident from the conversion of nuclear fuel,among which,researching and developing accident tolerant fuel was one of the effective measures to prevent serious nuclear accidents.Fuel cladding is one of the most important components in nuclear fuel system,and the choice of better performance of cladding material is the key to develop accident tolerant fuel.Molybdenum alloy can completely meet the requirements of new cladding material for the advantages of high melting point,good thermal shock resistance,high temperature stability,no reaction with hydrogen,etc.Thus,molybdenum alloy cladding is proposed one of the most promising new cladding materials in the world.However,molybdenum is easily oxidized to generate volatile MoO3 at high temperature which make it necessary to prepare protective coating on the surface of molybdenum alloy in order to protect it from high temperature in case of good mechanical properties.In this paper,FeCrAl coatings of different Al contents and different thicknesses were prepared on the molybdenum alloy substrate by magnetron sputtering by changing Al target current and deposition time.The microstructure,mechanical properties,high pressure corrosion resistance,high temperature steam corrosion and quenching properties of the coatings were tested and analyzed.The thickness of FeCrAl coatings with different Al target currents and different deposition time were 16.3?m-46.7?m and showed a FeCrNi solid solution structure.The Al content in the coatings increased with the increase of the Al target current and the Al existed in the form of amorphous,nano-crystalline,AlFe3 and solid solution to Fe lattice.The hardness of the coating increased and the elastic modulus decreased with the increase of the Al target current.While the hardness and elastic modulus of the coating decreased gradually.The coatings are well combined with substrates and the bonding strength between the coating and the substrate were well and decreased with the increase of Al content and coating thickness.The corrosion test of FeCrAl coatings on Mo substrates were carried out under different test conditions.Under the condition of 360?\18.6MPa\72h,the corrosion rate of Mo substrate was 4.2mg/dm2 and the morphology was not changed after corrosion test.In the condition of steam corrosion test of 1200?\0.1MPa\8h,the molybdenum substrate was protected from corrosion forming 4?m thick film on the surface and 12?m Mo diffusion layer.Under the condition of quenching after 1200?\0.1MPa\8h of steam corrosion,the coating was still complete after quenching and no macro crack.