超临界二氧化碳(S-CO₂)布雷顿(Brayton)循环系统具有较高的能量转换效率且对环境友好，因此在核能发电等领域有广阔的应用前景。电站中的热端部件材料因长期在高温CO₂环境中服役而面临严重的腐蚀问题。铁素体钢和奥氏体钢在该环境中的腐蚀机制有所不同，不能仅依靠Cr含量预测合金的腐蚀寿命。因此，本工作研究了铁素体钢T92及奥氏体钢316L在600 ℃、CO₂气氛中的腐蚀行为。结果表明，2种钢均发生了严重的氧化和渗C，在其表面均形成了外侧富Fe且内侧富Cr的双层氧化膜，并在钢的内部检测到明显的碳化物。316L奥氏体钢具有明显比T92铁素体钢更低的氧化速率，腐蚀500 h后的增重分别为1.38和10.51 mg/cm²。2者发生渗C的深度差别不大，分别约为241和329 μm。为了阻止CO₂对2种钢的腐蚀，开发了一种新型的耐腐蚀硼硅酸盐搪瓷涂层。采用喷涂-烧结法制备的搪瓷涂层在600 ℃、CO₂气氛中具有较高的热稳定性，且与基体界面结合良好，有效阻隔了CO₂的入侵，阻止了渗C反应的发生，并使钢的腐蚀增重降低了至少2个数量级。

Compared to the conventional Rankine steam cycle, the Brayton cycle system utilizing supercritical carbon dioxide (S-CO₂) as the working fluid offers significant advantages, including higher energy conversion efficiency, a more compact structure, enhanced safety, economic benefits, and a superior overall energy efficiency ratio. Consequently, the S-CO₂ Brayton cycle system holds promise for application in thermal power generation, fourth-generation nuclear power, new gas turbines, solar power generation, and other fields. In various operating conditions, material corrosion in high-temperature CO₂ environments has consistently been identified as a primary factor leading to the degradation of superheaters and reheaters. The corrosion mechanisms of steel in CO₂, particularly the differences between ferritic and austenitic steels, are not yet fully understood. T92 ferritic steel and 316L austenitic steel are widely recognized as preferred materials and have been extensively utilized as superheater/reheater components in power stations. Enamel coating has been considered a cost-effective solution for enhancing the oxidation resistance of steels without considerably degrading their mechanical properties. Therefore, this work investigated the corrosion behaviors of T92 ferritic steel and 316L austenitic steel, and enamel-coated steels in CO₂ at 600 ^oC. Results revealed rapid oxidation and carbon invasion for both T92 and 316L steels, with 316L austenitic steel exhibiting superior oxidation resistance and slightly better carbon invasion resistance due to its higher chromium content. Meanwhile, the mass gain after 500 h of corrosion was significantly higher for T92 ferritic steel than for 316L austenitic steel, reaching 10.51 and 1.38 mg/cm², respectively. The oxidation kinetics of all samples follows an approximately parabolic trend. A double-layered structure comprising an outer Fe-rich oxide layer and an inner Cr-rich oxide layer is formed on the surface of both steels. The interface between the inward growth of the inner layer and outward growth of the outer oxide layer corresponds to the initial steel surface. In addition, rapid carbon invasion and carburization cause more metal damage than oxidation. While T92 ferritic steel and 316L austenitic steel exhibited comparable resistance to carbon invasion, differences in their structures led to variations in carbide distribution within the steels. T92 ferritic steel demonstrated homogeneous carbide formation due to its high internal diffusion channel density, resulting in an intrusion depth of 329 μm after 500 h of corrosion. In contrast, carbides primarily precipitated at the austenitic grain boundaries of 316L austenitic steel, extending up to 241 μm within the same corrosion timeframe. Enamel-coated samples exhibited excellent corrosion resistance by effectively inhibiting oxidation and carburization reactions through isolating the contact between CO₂ and the steels. Consequently, the corrosion mass gain in these samples was reduced by at least two orders of magnitude. Furthermore, the glass phase of the enamel maintained thermal stability throughout the corrosion process, while the strong bond between the enamel coating and substrate provided long-term protection against thermal stress effects.