为了研究耐热钢在超临界二氧化碳布雷顿循环系统中的适用性, 选择目前电厂常用的两种金属材料(马氏体钢T91和奥氏体不锈钢HR3C), 在600 ℃/25 MPa的超临界二氧化碳环境中开展腐蚀试验。通过腐蚀质量增加研究了2种材料的腐蚀动力学规律; 利用扫描电子显微镜(SEM)和能谱仪(EDS)测量腐蚀产物层的厚度, 分析腐蚀产物的形貌和元素分布; 利用X射线衍射仪(XRD)对试样表面腐蚀产物进行物相分析。结果表明: 在超临界二氧化碳中, 马氏体钢T91和奥氏体不锈钢HR3C的腐蚀质量增加随时间呈近似抛物线的变化规律, 其中HR3C钢的耐腐蚀性能明显优于T91钢; T91钢的腐蚀产物层由外层Fe₃O₄、内层FeCr₂O₄和腐蚀产物/金属基体界面处的过渡区(金属基体和FeCr₂O₄的混合区)所组成; HR3C钢的表面腐蚀产物主要为具有保护性的Cr₂O₃氧化层。

In order to study the applicability of heat-resistant steel in supercritical carbon dioxide Brayton cycle system, two metal materials commonly used in power plants (martensitic steel T91 and austenitic stainless steel HR3C) were selected and used in corrosion tests in supercritical carbon dioxide environment of 600 ℃/25 MPa. The corrosion kinetics of the two materials was studied by corrosion mass grain. Scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) were used to measure the thickness of the corrosion product layer, and analyze the morphology and element distribution of the corrosion product. The phase of corrosion product on the surface of samples was analyzed by X-ray diffraction (XRD). The results show that in supercritical carbon dioxide, the corrosion mass grain of martensitic steel T91 and austenitic stainless steel HR3C displayed an approximate parabolic change with time. And the steel HR3C had better corrosion resistance than steel T91 obviously. The corrosion product of T91 consisted of inner layer (FeCr₂O₄), outer layer (Fe₃O₄), and a transition area between corrosion product and metal substrate (mixture of FeCr₂O₄ and substrate). The corrosion product on the surface of steel HR3C was a protective Cr₂O₃ oxide layer.