锆表面磁过滤阴极真空弧离子镀Cr涂层高温蒸汽氧化行为研究

High Temperature Steam Oxidation Behavior of Cr-coated Zr Fabricated by Filtered Cathodic Vacuum Arc Ion Deposition

采用磁过滤阴极真空弧离子镀(FCVAD)技术在纯锆表面制备了厚度约为4μm的Cr金属层,对比研究了它们在不同温度水蒸汽环境中的氧化行为,并利用XRD、XPS、SEM及EDS分析了Cr涂层及氧化膜的物相组成、微观结构及成分分布。结果表明,在900、1000和1100℃水蒸汽环境中,镀Cr涂层大幅度降低了锆的氧化速率,其单位面积氧化增重仅为同一温度下锆基体的1/4、1/6和4/9。氧化初期,Cr涂层表面生成一层均匀致密的Cr2O3膜,当Cr层被消耗完后,Cr2O3/Zr界面上部分Cr2O3被Zr还原成金属Cr,锆基体氧化生成ZrO2。镀Cr涂层样品的氧化激活能达293.17 kJ/mol。

A Cr coating of about 4μm thick was prepared on pure zirconium by filtered cathodic vacuum arc ion deposition technology(FCVAD),and the high-temperature oxidation properties of bare and Cr-coated Zr were measured using a thermogravimetric analyzer(TGA)in steam environment at different temperatures.The phase composition,microstructure and composition distributions before and after the steam oxidation tests were characterized by X-ray diffraction analyzer(XRD),X-ray photoelectron spectroscopy(XPS),scanning electron microscope(SEM)and energy dispersive X-ray spectroscopy(EDS).It was found that the mass gain per unit area of Cr-coated Zr is only 1/4,1/6 and 4/9 of that of bare Zr after 3600 s exposure in 900,1000 and 1100℃steam environment,respectively.In the initial stage of steam oxidation,a compact and uniform Cr2 O3 layer is formed on the surface of Cr layer,significantly reducing oxygen or steam diffusion inwards.After Cr coating is completely oxidized into Cr2 O3,Zr substrate is gradually oxidized,but the Cr2 O3 at Cr2 O3/Zr interface is reduced to form Cr.In addition,the oxidation activation energy of the Cr-coated Zr is up to 293.17 kJ/mol.