镍基合金C276在超临界水中的腐蚀行为

Corrosion behavior of Ni-base alloy C276 in supercritical water

研究镍基合金C276在550~650℃/25 MPa超临界水中的腐蚀特性.采用腐蚀增重、扫描电镜、能谱和X射线衍射方法分析材料的氧化动力学、氧化膜形貌、合金元素分布和组织结构.结果表明,C276合金在超临界水中以均匀腐蚀为主,其腐蚀增重服从抛物线生长规律.当温度由550℃升高到600℃时,材料的腐蚀增重大约升高到3倍;当温度进一步升高到650℃时,材料的腐蚀增重反而下降.C276合金表面氧化膜分层不明显,氧化膜的主要成分为（Ni,Fe）Cr2O4,同时其表层离散分布着大量的Ni O氧化物颗粒.C276合金表面氧化膜的保护性能主要取决于氧化膜内Cr含量,Cr含量越高其结构越致密,从而保护性能也越好.

This article is focused on the corrosion behavior of Ni-base alloy C276 exposed to 550- 650 ℃ /25 MPa supercritical water. The oxidation kinetics,oxide morphology,element distribution and structure of the oxide film were analyzed by using weight gain measurement,scanning electron microscopy,energy spectrometry,and X-ray diffraction analysis. It is shown that C276 alloy exhibits general corrosion in the supercritical water,and the weight gain is subject to parabolic growth kinetics. The weight gain of C276 alloy at 600 ℃ is approximately three times that of C276 alloy at 550 ℃,while the weight gain shows a decline when the temperature increases to 650 ℃. The oxide film is not distinguishable and is mainly consisted of（ Ni,Fe） Cr_2O_4. A large number of Ni O oxide particles are observed on the oxide film. The protective ability of the oxide film is dependent upon Cr content,and the higher the Cr content,the better the protective ability is.