SA-210C和15CrMoG在给水加氧处理工况下的氧化特性研究  

Oxidation Characteristics of SA-210C and 15CrMoG under Oxygenation Treatment Condition

作　　者：查方林 刘凯 杨漫兮 袁新民 王凌 ZHA Fang-lin;LIU Kai;YANG Man-xi;YUAN Xin-min;WANG ling(State Grid Hunan Electric Power Corporation Research Institute,Changsha 410007,China;Hunan Xiangdian Test Research Institute Co.,Ltd,Changsha 410007,China;School of Chemistry and Molecular Sciences,Wuhan University,Wuhan 430072,China)

机构地区：[1]国网湖南省电力有限公司电力科学研究院,长沙410007 [2]湖南省湘电试验研究院有限公司,长沙410007 [3]武汉大学化学与分子科学学院,武汉430072

出　　处：《表面技术》2018年第11期181-188,共8页Surface Technology

摘　　要：目的研究给水加氧工况下溶解氧浓度对锅炉金属氧化行为的影响,获取给水加氧处理的最佳溶解氧浓度。方法以高压釜模拟发电厂高温高压水汽环境,在不同氧浓度下对SA-210C和15CrMoG试片进行高温氧化,分别绘制两种材料的时间-增重曲线,并拟合氧化动力学方程,研究了加氧处理对材料氧化动力学规律的影响。通过电化学阻抗法测试得到极化阻抗R_p和氧化膜电容Q_f,结合SEM结果分析了氧化膜的结构。通过伏安扫描得到了氧化膜中Fe(II)和Fe(III)的还原峰高,结合XRD测试分析了氧化膜的物相组成。结果SA-210C和15CrMoG在50μg/L溶解氧下氧化30 d后的增重分别为1.714 g/m^2和1.804 g/m^2,加氧处理时,两种材料的极化电阻均达到了10~6?·cm^2量级,比无氧时高1个数量级,氧化膜结构更加致密。加氧处理时,SA-210C氧化膜为Fe_3O_4,15CrMoG氧化膜为Fe_3O_4+Fe_2O_3。结论SA-210C和15CrMoG的高温氧化行为符合?m=kt^a规律,加氧处理显著加速了SA-210C初期氧化膜的生长,但抑制了后期的氧化速率。加氧处理主要影响15CrMoG氧化膜的初期生长速率,对后期氧化动力学行为的影响较小。SA-210C和15CrMoG的最佳加氧浓度均为50μg/L。The work aims to study the effect of dissolved oxygen concentration on oxidation behavior of boiler metals under Oxygenation Treatment(OT)condition and the optimal dissolved oxygen concentration for OT of feedwater.The high temperature and high pressure environment in Power Plant was simulated with autoclave and SA-210C and 15CrMoG were oxidized by high temperature under different dissolved oxygen concentration.The time-weight gain curves of two materials were drawn and the oxidation kinetic equations were fitted to study the effects of OT on the kinetics.Polarization impedance(Rp)and oxide film capacitor(Qf)were obtained through electrochemical impedance spectroscopy(EIS)test and then used to analyze oxide film structure with SEM results.Reduction peak heights of Fe(II)and Fe(III)in oxide film were obtained through voltammetric scanning and then used to analyze phase composition of oxide film with XRD test.The weight gain of SA-210C and 15CrMoG after being oxidized at 50μg/L dissolved oxygen for 30 days was 1.714 g/m^2 and 1.804 g/m^2,respectively.The polarization resistance of both materials reached the level of 10^6Ω·cm^2 under OT condition which was one order of magnitude higher than that of anaerobic condition and the structure of oxide film was more dense.The oxide film composition of SA-210C was Fe3O4 and that of 15CrMoG was Fe3O4+Fe2O3 under OT condition.The oxidation behavior of SA-210C and 15CrMoG at high temperature is consistent withΔm=kta law.OT significantly accelerates the growth of the initial oxide film of SA-210C,but inhibits the oxidation rate at the later stage.OT mainly affects the initial growth rate of 15CrMoG oxide film,and has few effects on the later oxidation kinetics.The optimal oxygen concentration of SA-210C and 15CrMoG is 50μg/L.

关 键 词：加氧处理 溶解氧 氧化动力学 极化电阻 FE3O4 FE2O3 

分 类 号：TG172[金属学及工艺—金属表面处理]