高熵合金與核能結構材料在超臨界水環境下之腐蝕行為研究

Corrosion Performance of High-entropy Alloy and Candidate Materials used in Supercritical Water Environments

隨著電力的增加，火力電廠廣泛的採用高效率與大容量的超超臨界設備。同時蒸氣循環的操作溫度提高，使用於超臨界環境下的材料必須要能提供抗腐蝕的能力，尤其是結構材料的部分。新材料的選擇與特性的比較變得尤其重要。對於超超臨界蒸氣發電機組，採用改善的含鉻9-12%的麻田散鐵不鏽鋼以及沃斯田系不銹鋼。
本研究將進行適用材料的腐蝕行為研究，建立模擬高溫高壓超臨界水循環系統，可維持在650oC溫度與25 MPa壓力下，且可控制與監測水化學狀態。測試的材料包含高熵合金、麻田散鐵系不銹鋼-P92、沃斯田系不銹鋼-304H與鎳基合金Haynes 230，採用重量改變測試、U-bend實驗、以及表面分析來進行抗腐蝕能力測試。從重量改變測試與截面分析顯示高熵合金以及Haynes 230有較好的抗腐蝕能力，304H在實驗過程就有氧化層脫落現象，而P92的氧化物則具有雙層結構，外層為Fe3O4，內層則為鐵鉻氧化物。

With increasing the electrical generation, the high efficiency and large capacity of ultra-supercritical(USC) instruments are widely used in the world. As the temperature of the steam cycles increases, the candidate materials must provide sustained corrosion resistance in the supercritical water environments. Thus improved martensitic 9-12% chromium steels and austenitic steels were adopted in ultra-supercritical condition.
Some candidate materials will be investigated in an ultra-supercritical water environment in this study and an ultra-supercritical water recirculation loop system will be established. The system would sustain a temperature of 650 oC and a pressure of 25 MPa, and the water chemistry of the coolant in the loop system can be easily controlled and monitored.
Some materials will be selected for corrosion resistance in the ultra-supercritical water environment by U-bend, weight change, and ECP tests. The tested materials include the high entropy alloys, the nickel alloy - Haynes 230, the martensitic steels-T92, and the austenitic steels-304H, developing USC candidate material could be useful to operate at high temperature for a practical length of time without failure.