超临界二氧化碳环境中600合金和304不锈钢的均匀腐蚀行为研究

Study on Uniform Corrosion Behavior of 600 Alloy and 304 Stainless Steel in Supercritical Carbon Dioxide Environment

为遴选可用于超临界二氧化碳核反应堆的结构材料,通过实验研究了应用于传统核反应堆中的两种合金(600合金和304不锈钢)在650℃、20 MPa的超临界二氧化碳环境中的均匀腐蚀行为,运用增重法评价了材料的腐蚀动力学规律,采用扫描电镜、能谱仪和X射线衍射仪分析了氧化膜形貌、结构和化学成分。结果表明,两种材料的腐蚀增重均服从抛物线生长规律,其中600合金的耐腐蚀性能优于304不锈钢;腐蚀500 h后,600合金表面氧化物厚度约为5μm,主要成分为NiCr_(2)O_(4),结构致密,具有保护性,其氧化膜及基体中均未发现明显渗碳行为;腐蚀500 h后,304不锈钢表面氧化膜可达约45μm,为双层结构,外层为Fe_(3)O_(4),内层为NiFeCrO_(4),结构疏松,发生显著渗碳现象。本研究揭示了上述材料在超临界二氧化碳中的腐蚀机理,为超临界二氧化碳核反应堆结构材料的选择提供了数据支持。

In order to select the structural materials that can be used in the supercritical carbon dioxide nuclear reactor,the uniform corrosion behavior of two kinds of alloys(600 alloy and 304 stainless steel)used in the traditional nuclear reactor in the supercritical carbon dioxide environment at 650℃and 20 MPa is studied through experiments.The corrosion kinetics of the material is evaluated by weight gain method,and the morphology,structure and chemical composition of the oxide film are analyzed by scanning electron microscope,energy dispersive spectrometer and X-ray diffractometer.The results show that the corrosion weight gain of the two materials obeys the parabolic growth law,and the corrosion resistance of 600 alloy is better than that of 304 stainless steel.After 500 h corrosion,the oxide thickness on the surface of 600 alloy is about 5μm,the main component is NiCr_(2)O_(4),which is compact in structure and protective.No obvious carburization is found in its oxide film and matrix;After 500 h corrosion,the oxidation film on 304 stainless steel surface can reach about 45μm.It is a double-layer structure,the outer layer is Fe_(3)O_(4),and the inner layer is NiFeCrO_(4).The structure is loose,and significant carburization occurs.This study reveals the corrosion mechanism of the above materials in supercritical carbon dioxide,and provides valuable data support for the selection of structural materials for supercritical carbon dioxide nuclear reactors.