锆合金表面Cr基涂层的耐高温氧化性能

用磁控溅射法在锆合金基体表面制备Cr和CrAl层,并使其在1200℃/1 h水蒸汽中氧化,用扫描电子显微镜(SEM)、能谱仪(EDS)和X射线衍射仪(XRD)等手段表征氧化前后涂层和Zr合金基体的微观结构,研究了两种涂层在(反应堆失水(LOCA)事故情况下的)高温蒸汽环境中的抗氧化性能。结果表明：在1200℃/1 h水蒸汽中氧化后没有涂层的锆合金基体表面生成厚度约为100 μm的氧化膜；而在Cr涂层表面生成的致密Cr₂O₃层其厚度约为4 μm,表明氧化速率显著降低。CrAl涂层氧化后表面生成致密的Cr₂O₃和Al₂O₃混合氧化层,其厚度只有0.8 μm,表明氧化速率进一步降低。这些结果表明: 用磁控溅射法在锆合金表面制备的Cr和CrAl涂层,在1200℃水蒸气环境中均表现出良好的耐氧化性能。在Cr涂层表面生成的氧化膜厚度约为未涂层锆合金氧化层的1/25,CrAl涂层氧化膜厚度低于锆合金表面氧化层的1/100。

High Temperature Oxidation Resistance of Cr Based Coating on Zirconium Alloy

Coatings of Cr and CrAl (14% Al, mass fraction) were prepared on Zr-4 alloy substrate by magnetron sputtering method. The oxidation resistance of Cr and CrAl coatings in high temperature steam (simulated the situation of LOCA accident) was investigated by means of steam oxidation test at 1200℃ for 1 h, scanning electron microscope (SEM), energy dispersive spectroscope (EDS) and X-ray diffractometer (XRD). The results show that the thickness of oxide scaled formed on the uncoated Zr-4 alloy is about 100 μm after steam oxidation at 1200℃/1 h, while a dense Cr₂O₃ scale of about 4 μm in thickness formed on the Cr coating surface, and the oxidation rate decreases significantly. The oxidation rate of CrAl coating is even lower than that of Cr coating due to the formation of a dense scale of mixed oxides Cr₂O₃ and Al₂O₃ of about 0.8 μm in thickness. It can be concluded that Cr and CrAl coatings prepared by magnetron sputtering on Zr-4 alloy have good resistance to high temperature steam oxidation at 1200℃. The thickness of the oxide scale formed on the surface of Cr coating is about 1/25 of that on Zr-4 alloy, and the thickness of the oxide scale on the surface of CrAl coating is less than 1/100 of that on Zr-4 alloy.