Incoloy 800H合金在675℃蒸汽中的氧化机理研究

Oxidation mechanism of Incoloy 800H alloy in steam at 675 ℃

Incoloy 800H合金被用于我国首台高温气冷堆核电机组传热管高温段,其最高设计温度达到675℃,对其在设计温度下的蒸汽氧化性能进行研究,采用扫描电镜(SEM)、透射电镜(TEM)和X射线能谱(EDS)等表征了Incoloy 800H合金的氧化层结构。试验结果表明:800H合金在675℃蒸汽中的氧化动力学曲线接近立方规律,氧化增重的立方与时间接近正比关系。氧化层呈双层结构,外层主要为Fe3O4和Fe2O3及少量Ni,内层为中间分布着少量金属Ni、Al2O3和TiO_(2)颗粒的Cr2O3纳米晶,在邻近氧化层的基体金属中,分布着Cr2O3、Al2O3和TiO_(2)内氧化颗粒。

Incoloy 800H is used for high temperature section of heat transfer tubes of the first high temperature gascooled reactor nuclear power unit in China,of which the highest design temperature is 675℃.The steam oxidation properties of the Incoloy 800H at the design temperature are investigated.The structure of oxide scale of the Incoloy 800H is characterized by scanning electron microscopy (SEM),transmission electron microscopy (TEM) and X-ray energy dispersive spectroscopy (EDS).The results show that,the oxidation kinetic curve of the 800H alloy in steam at 675℃is close to the cubic law,namely the cubic of the weight gain is nearly proportional to the oxidation time.The oxide scale has a double-layer structure.The outer layer is mainly composed of Fe3O4,Fe2O3and a small amount of Ni,and the inner layer is Cr2O3nanocrystalline with a small amount of Ni,Al2O3and TiO_(2)particles distributed in it.Some internal oxide particles of Cr2O3,Al2O3and TiO_(2)are distributed in the matrix metal adjacent to the oxide layer.