先进超超临界电站锅炉4种候选材料在700℃超临界水中的氧化行为

Oxidation behaviors of four candidate materials for the advanced ultra-supercritical water power plant are studied in supercritical water at 700℃/25 MPa for 320 h. These four materials are Inconel 617, Inconel 740, HR6W and Sanicro 25. The 2-D and 3-D morphology, cross-sectional structure of the oxides formed on the alloys after exposure are observed, and the oxide phase are analyzed. The results are compared with those in other literature. Results show that the structure of the oxide films formed on HR6W and Sanicro 25 with high iron content forms a double layer structure with a Fe-rich outer layer and a Cr-rich inner layer after exposed in supercritical water at 700℃ for 320 h, while only one Cr-rich spinel structure layer is formed on Inconel 740 and Inconel 617 after exposed to supercritical water. The increase of ambient temperature and ambient pressure promotes the oxidation weight gain of the alloys in supercritical water. The reaction of supercritical water with Fe on the alloy surface to produce hydrogen has an inhibitory effect on the formation of continuous chromium oxide layer on the alloy surface. The order of the weight gain data and the oxide layer thickness of the four candidate materials is Sanicro 25>HR6W>Inconel 740>Inconel 617.