【作者】 蒋娅；

【导师】 李宇春；

【作者基本信息】 长沙理工大学 ， 物理化学， 2012， 硕士

【摘要】 随着我国各火力发电厂锅炉设备容量与蒸汽参数的增加，越来越多的锅炉爆管事故随之发生。统计电站锅炉事故中发现，受热面管（水冷壁管、过热器管、再热器管、省煤器管，又称“四管”）的爆漏损坏事故最为严重和常见，而对于承受高温和高压蒸汽作用的过热器管来说，氧化和腐蚀更是造成爆管的主要因素，其抗氧化和抗腐蚀性能是重要的指标。T91钢作为过热器管的主要材料，非常有必要对其腐蚀行为及腐蚀机理进行研究。本文以T91钢为研究对象，主要研究了T91在钝化、侵蚀以及酸性介质缓蚀方面的行为和特性。采用Tafel极化曲线、交流阻抗、电化学噪声以及高压釜挂片等实验方法，并使用SEM、XRD、EDS对挂片后的试片进行表征，分析并讨论T91钢在腐蚀及钝化过程中的腐蚀速度、缓蚀效率及其腐蚀机理。本课题研究发现：（1）在不同温度、pH值条件下对T91钢进行腐蚀实验，pH=9时，T91钢的耐蚀性最佳；设定溶液pH值为9，对T91钢在不同温度，不同浓度的Cl^-、SO₄^2-溶液中进行电化学和挂片实验，将Icorr、Vcorr、Rct值进行对比，同等条件下SO₄^2-对T91钢的腐蚀影响大于Cl^-。（2）选择不同浓度的亚硝酸钠为钝化液，在不同温度及pH值的条件下对T91钢进行钝化，通过电化学和硫酸铜滴定实验，结果表明T91钢的最佳钝化条件为：30℃，pH为9.5，NaNO₂浓度为0.5%。最佳钝化条件下对T91钢进行钝化后，用1.0mol/L的NaCl溶液对其进行腐蚀研究，对比钝化前后的实验数据，Icorr值降低了两个数量级，Ecorr值正移，Rct值也增大了一个数量级，说明钝化膜有效的降低了Cl^-对T91钢的侵蚀。（3）对T91钢锈片在16%盐酸溶液进行电化学实验，作电位-时间图，发现当电位导数值为零时，除锈效果最好，判定此时为酸洗终点。盐酸的质量分数越大，整个酸洗时间越短；温度越高，酸洗时间也越短。由于盐酸有强挥发性，根据实验结果以及拟合曲线方程可知：最佳盐酸酸洗质量分数为16%，最佳酸洗温度为50℃。实验发现在16%盐酸溶液中添加一定量的聚环氧琥珀酸时，对T91钢有一定的缓蚀作用，其缓蚀率随着PESA浓度的增加而增大，随着温度升高而降低，当PESA浓度大于20 g/L时，钢材的缓蚀效率基本保持不变。PESA在T91钢表面的吸附基本符合Langmuir吸附等温式，至此说明PESA不再只作为碱性缓蚀剂使用，在酸性条件下也可以使用。更多还原

【Abstract】 Along with the increase of our country the power plant boiler equipment capacity and steamparameters, then more and more of the boiler pipe explosion accident happened. Statisticalpower station boiler accidents founded that the damage blasting leaks of in heating tube（water-wall tubes, overheating pipes, reheater pipes, economizer tube, say again "four tubes"）was the most serious and widespread.For the overheating pipes under high temperature andhigh pressure steam, the main factors of pipe explosion was oxidation and corrosion, theoxidation resistance and corrosion resistance were important indexs. T91 steel as the mainmaterial of overheating pipes, the study of the corrosion behavior and corrosion mechanismwas very necessary.The passivation, erosion and acid corrosion corrosion behaviors and characteristics of T91wasstudied in this article. Electrochemistry test methods and suspended coupon experiment wereused to obtain corrosion rate,the corrosion inhibitor rate and related datas, included Tafelpolarization curve, Electrochemical impedance spectroscopy, Electrochemical noise,specially,and using SEM、XRD、EDS to test the surface of the specimens.This paper studied found that:（1）The corrosion behavior of T91 steel was studied fromdifferent pH values and temperatures, The best corrosion resistance points of T91 steel waspH=9. Setting the pH value of solution was 9,the experiment of electrochemical and hangpiece were did in different temperature and different concentration of Cl^-、SO₄^2- solutions forT91 steel. Contrasted results of Icorr、Vcorr、Rct, SO₄^2- than Cl^- the corrosion affect larger of T91steel under the same conditions.（2） Different concentrations of sodium nitrite was choosed forpassivation solution.In different temperature and pH value conditions of T91 steel forpassivation, through the electrochemical and copper sulfate titration experiment, The best passivation T91 steel condition was: 30℃, pH 9.5, concentration of NaNO₂was 0.5%. T91was eroded in 1.0mol/LNaCl after the best passivation treatment. Contrasted of theexperimental data before and after the passivation, Icorrvalue reduced two orders of magnitude,Ecorrpositive moved, Rctvalue also increased one order of magnitude. Passive film effectivelyreduced the Cl^-to the erosion of T91 steel.（3） The electrochemical experiments of rustycoupon of T91 was tested in the 16% hydrochloric acid, Drawed potential-time figure.Foundthat when the derivative value of the potential was Zero, the derusting effect was the best ,Judged for pickling end at this time．When the mass fraction of hydrochloric acid was higherand the temperature of pickling was higher,the pickling time was shorter．Due to the strongvolatile of hydrochloric acid , it can be got that the optimum pickling temperature was50℃,and the optimum mass fraction of HCl which was used to pickling was 16% based onthe experimental results and fitting curve equation．The experiment found that there weresome corrosion inhibition of T91 steel when added a certain amount of poly epoxy succinicacid（PESA） into 16% hydrochloric acid solution,.The inhibition efficiency of PESA increasedwith the increasing concentration, decreased with the increasing temperature, The inhibitingrate remain unchanged when PESA concentration more than 20g/L. PESA conformed toLangmuir adsorption isotherm. So PESA used not only in alkaline conditions, but also used inacid conditions.更多还原