Preparation And Corrosion Properties Of FeCrAlY Coatings

The cladding material is an important original part of the nuclear power reactor.The better performance of the claddina material not only provides guarantee for the normal operation of the nuclear power plant,but also provides sufficient time for the rescue in the event of a nuclear power accident.Molybdenum alloys have high melting point,high hardness,good resistance to radiation swelling and high temperature creep resistance,and are expeted to be developed as melear materials in nuclear power plants.The molybdenum oxidation product MoO₃ has volatility.By preparing a high-temperature anti-corrosion coating on the surface of the molybdenum tube to form a composite cladding material,the oxidation of molybdenum can be solved.In this paper,FeCrAlY coatings with different Y target currents and different deposition times were prepared by closed field unbalanced magnetron sputterino ion plaLino.The microstructure and mechanical properties of Lhe coating and the high temperature and high pressure corrosion resistance of the coating were studied.The influence of Y target current and deposition time on the microstructure and mechanical properties of the coating was revealed.The corrosion resistance mechanism of the coating was discussed.The FeCrAlY coating has the thickness of 9.0?33.6?m and the Y content of 0.18wt%?1.78wt%;the coating is mostly FeCr solid solution phase;the Y element is present in the coating with Al40.43Cr6.57Y6 phase and coating There is a small amount of Fe3Al phase in the coating;as the Y target current increases,the hardness of the coating increases,the modulus of elasticity increases first and then decreases,and the surfacc roughness decreases.The hardness and elastic modulus of the coating inerease with the deposition time Decreased the surface roughness increased;the deposition time increased from 3h to 5h,and the coating grain size increased from 350nm to 450nm.The coating with no Y element added was comparcd with the coating with a Y clcment content.of 1.78 wt%.and the grain size decrcascd from 120nm to 56 nn.The FeCrAlY coating has good bonding strength with the substrate and is superior to the FeCrAl coating without the addition of the Y element.The FeCrAlY coating samples prepared in the high temperature and high pressure reactor were corroded at 360? and 18.6MPa for 72h,and the weight gain rate of the coated molybdenum tubes was lower than that of molybdenum tubes and FeCrAl after 3h and 5h.The weight gain rate of coated molybdenum tube and Zr alloy under high temperature and high pressure corrosion under the same conditions;the surface of the coating is covered by a dense mixed layer of Cr2O3 and Al2O3,but the coating with deposition time of 5h is covered by oxide The original ridge morphology of the coating was preserved;the XRD of the coating still showed the FeCr solid solution phase,and there was no obvious oxide peak.After 144h corrosion,the coating weight gain rate was 4.45mg/dm2 and 6.38mg/dm2 respectively;XRD It is shown as FeCr solid solution and Al2O3 phase.The surface of the coating with deposition time of 3h is evenly covered with a dense non-porous Cr2O3 and Al2O3 mixed oxide layer.The coating time is 5h.The surface oxide layer is affected by stress and surface roughness.It is relatively loose and has some peeling.