摘要
为研究水冷壁管材料20G和15CrMo在含Cl-溶液中的点蚀特性,通过常温电化学实验和高温挂片实验,对其常温、高温腐蚀特性进行分析,用透反射金相显微镜、扫描电子显微镜(scanning electron microscopy,SEM)、X能谱仪(energy dispersive spectrometer,EDS)、X射线衍射(X-raydiffraction,XRD)对试片表面形态和组分进行表征与分析。结果表明,常温条件下,Cl-对这2种材料都有侵蚀性,其中15CrMo耐Cl侵蚀性能比20 G优秀。高温条件下,Cl-对20G和15CrMo的侵蚀性严重,促进材料的溶解,加速材料的点蚀。常温条件下Cl-与OH在金属表面存在竞争吸附作用,形成复合中间体FeOHCl,高温条件下Cl-的作用相当于催化剂,促进Fe2+水解,生成疏松无保护性的Fe3O4。在电厂实际运行中,应控制给水中Cl-质量浓度低于0.2mg/L。
In order to investigate the influence of Cl- on the pitting corrosion of water-wall tube 20 G and 15CrMo materials at room temperature and high temperature, a series of experiments including electrochemical measurement and high-temperature weight loss were carried out. The tested specimen surface was characterized by transmission reflection metallurgical microscopy, scanning electron microscopy （SEM）, energy dispersive spectrometer （EDS）, and X-ray diffraction （XRD）. The experiment results show that Cl- accelerate pit corrosion of 20 G and 15CrMo specimens at room temperature, 15CrMo specimens have higher corrosion resistance than 20G specimens, and Cl- also accelerate corrosion at high temperature. The corrosion mechanism of C1- for water-wall tube is the competitive adsorption mechanism of C1- and OH- at room-temperature, an intermediate complex （FeOHCl） is formed; Cl- acted as a catalyst at high-temperature, which induce the Fe2＋ hydrolysis, and form loose and unprotected Fe3O4 film. In the actual operation of power plant, Cl- concentrations must be controlled less than 0.2 mg/L in feed water.
出处
《中国电机工程学报》
EI
CSCD
北大核心
2012年第2期67-72,共6页
Proceedings of the CSEE
基金
湖南省自然科学基金项目(09JJ6067)
湖南省科技攻关项目(2010GK3171)~~
