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研究了3种700℃超超临界燃煤锅炉备选高温合金Inconel 740,CCA 617,GH 2984在760℃现役机组煤灰腐蚀介质中的高温腐蚀行为。结果表明:镍基合金Inconel 740和CCA 617均能形成保护性的Cr2O3氧化膜,局部点蚀为其主要失效形式。点蚀区域氧化膜为多层结构,由外到内依次为Ni(Co)O、Cr2O3(TiO、Al2O3)以及少量内层硫化物;较高Cr、Al含量提高了Inconel 740合金的耐蚀性能;挥发性产物与氧化膜微区溶解降低了CCA 617合金氧化膜的致密性。GH 2984合金因含有较多的Fe未能形成保护性的氧化膜,氧化膜分层生长,且出现了严重的剥落现象。
The corrosion behaviors of Inconel 740, CCA 617 and GH 2984, which are the candidate superalloys of 700 ℃ ultra-supercritical coal-fired boilers, were studied at high temperature in the corrosive medium of coal ash of the active unit at 760 ℃. The results show that both the Inconel 740 and the CCA 617 can form a protective Cr2O3 oxide film, and local pitting corrosion is the main failure mode. The oxide film in the pitting area is a multi-layer structure with Ni (Co) O, Cr2O3 (TiO, Al2O3) and a small amount of inner sulfide from outside to inside. Higher Cr and Al contents improve the corrosion resistance of Inconel 740 alloy The micro-area dissolution of volatile products and oxide films reduced the compactness of CCA 617 alloy oxide film. GH 2984 alloy due to containing more Fe failed to form a protective oxide film, the oxide film layered growth, and the emergence of a serious spalling.