| Nuclear power has many advantages,such as large power generation,low cost,independent on the natural environment,and low pollution,so it has become the main source of electricity in many countries.The safety of nuclear power materials has always been a concern,especially after the Fukushima nuclear accident in Japan,the development of an accident tolerant fuel system that can improve the reactor's ability to withstand accidents has become a key direction in the nuclear industry.As the shell of nuclear fuel,the performance of the cladding material is an important guarantee for the normal operation of the reactor and the resistance to serious accidents.Molybdenum alloy is considered to be one of the candidate materials for accident tolerant fuel cladding due to its excellent high-temperature mechanical properties and good radiation resistance.But the high temperature oxidation resistance of molybdenum is poor,so it is necessary to find a protective coating suitable for molybdenum cladding,which can improve the high temperature oxidation resistance while retaining its good mechanical properties.In this paper,magnetron sputtering technology is used to prepare three different coatings on the molybdenum alloy,namely FeCrAl coating,FeCrAlY coating and Cr coating.The microstructure and mechanical properties of the coating were tested and analyzed,and the protective ability of the coating on the molybdenum under high pressure and high temperature steam environment was studied,and the corrosion mechanism was discussed.The thickness of the three coatings is about 18?19?m.The FeCrAl coating and FeCrAlY coating mainly exist in the FeCr solid solution,their hardness is significantly greater than Cr coating,but the elastic modulus is slightly lower than Cr coating.The bonding strength of the Cr coating and the molybdenum is significantly better than the other two.Even when the scratch load was 100N,the Cr coating on the molybdenum substrate has no cracks and peeling.Three different coatings on molybdenum have good oxidation resistance under the experimental conditions of 360?\18.6 MPa\30 days.The corrosion weight gain rates of FeCrAl coating,FeCrAlY coating and Cr coating samples were 11.535 mg/dm2,3.599 mg/dm2,and 7.287 mg/dm2,respectively.Three different coating samples were carried out to 1200?\0.1 MPa steam corrosion experiments for 8h,24h,48h,and 72h.After corrosion test,Al2O3,Fe3O4 and MoO3 were formed on the surface of FeCrAl coating and FeCrAlY coating samples,although the coatings were completely oxidized and the thickness increased significantly,they can ensure the completeness of the samples within 24 h.A continuous and dense Cr2O3 film was formed on the surface of the Cr coated sample,which protected the molybdenum from oxidation.After 72h,the Cr coating was partially cracked. |
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