Li Ji, He Xikou, Xu Bin, Tang Zhengxin, Fang Caishun, Yang Gang
Research Institute of Special Steel, Central Iron and Steel Research Institute, Beijing 100081, China.
Nuclear Power Institute of China, Chengdu 610014, China.
Materials (Basel). 2022 Apr 14;15(8):2862. doi: 10.3390/ma15082862.
The 9-12% Cr ferritic-martensitic heat-resistant steel is the main candidate structural material for the Lead-cooled Faster Reactor. The lower Gibbs free energy change of Si oxide can promote the formation of a stable oxide layer, which can improve the corrosion resistance of the material. Therefore, it is of great significance to study the effect of silicon (Si) on the corrosion resistance of T91 steel in lead-bismuth eutectic (LBE). The corrosion resistance of T91 steel with Si contents of 0.5 wt.%, 1.3 wt.%, and 2.0 wt.%, both in dynamic and static LBE at 550 °C, was investigated. The microstructure was analyzed by X-ray diffraction (XRD), scanning electron microscope (SEM) and transmission electron microscope (TEM), while the oxide films were characterized by electron probe microanalysis (EPMA). Results show that the addition of Si is conducive to improving the corrosion resistance of T91 steel in LBE. T91 steel with high Si content has a thinner and more stable oxide film. The change of Si content can change the contact angle between the steel and LBE, and the contact angle is the largest when the Si content is 1.3 wt.%. The Si-rich oxide layer is usually located in the inner oxide layer, which promotes the formation of a Cr oxide layer located in the internal oxidation zone (IOZ). Si will not enter the precipitated phase, but only change the ferrite content. The oxidation model of T91 steel containing Si in LBE was also proposed.
9-12%Cr铁素体-马氏体耐热钢是铅冷快堆主要的候选结构材料。氧化硅较低的吉布斯自由能变化能促进稳定氧化层的形成，从而提高材料的耐腐蚀性。因此，研究硅（Si）对T91钢在铅铋共晶（LBE）中的耐腐蚀性的影响具有重要意义。研究了含硅量分别为0.5 wt.%、1.3 wt.%和2.0 wt.%的T91钢在550℃动态和静态LBE中的耐腐蚀性。通过X射线衍射（XRD）、扫描电子显微镜（SEM）和透射电子显微镜（TEM）分析微观结构，同时用电子探针微分析（EPMA）对氧化膜进行表征。结果表明，添加硅有利于提高T91钢在LBE中的耐腐蚀性。高硅含量的T91钢具有更薄且更稳定的氧化膜。硅含量的变化会改变钢与LBE之间的接触角，当硅含量为1.3 wt.%时接触角最大。富硅氧化层通常位于内氧化层，促进了位于内氧化区（IOZ）的氧化铬层的形成。硅不会进入析出相，只会改变铁素体含量。还提出了含硅T91钢在LBE中的氧化模型。
