【作者】 秦丽雁；

【导师】 宋诗哲；

【作者基本信息】 天津大学 ， 应用化学， 2006， 博士

【摘要】 不锈钢是人类应用最广的绿色环保金属材料。在使用过程中,如果加工或使用不当,易导致局部腐蚀,晶间腐蚀是不锈钢局部腐蚀中最危险的破坏形式之一,但迄今为止仍然没有一种快速、完善、定量、无损的现场检测晶间腐蚀敏感性的方法。近年来随着人们环保意识的提高,为满足不同需求的功能性不锈钢新产品也不断问世,然而目前关于功能性不锈钢在应用环境中腐蚀问题的报道很少,本文围绕太原钢铁公司生产的传统不锈钢及其研制开发的新型304光亮型和430抗菌型不锈钢在应用中的腐蚀问题展开工作。针对不锈钢晶间腐蚀的检测,采用电化学测试、扫描电镜观察等方法研究了不锈钢晶间腐蚀的敏感温度及晶间腐蚀发生、发展过程。尝试采用电化学阻抗技术检测晶间腐蚀,初步分析了晶间腐蚀的电化学等效电路,并据此计算了电化学等效电路参数,讨论了等效电路参数与晶间腐蚀敏感程度的关联性。研究结果表明:奥氏体与铁素体不锈钢晶间腐蚀的敏感温度不同,在进行不锈钢晶间腐蚀敏感性检测时,应根据钢种选择相应的敏化处理制度,避免不合格的原材料出厂使用;EPR极化过程中固溶态和敏化态304不锈钢在再活化区,EIS图呈现双容抗弧特征,低频下敏化态比固溶态不锈钢阻抗模值小一个数量级,敏化态不锈钢发生了晶间腐蚀;钝化膜表面界面电容Cc及晶间腐蚀活性区界面电容Cd随敏化态不锈钢晶间腐蚀程度的加剧呈上升趋势,电荷传递电阻Rt呈现下降趋势,与晶间腐蚀的发生和发展有一定的对应关系。研究结果为运用电化学阻抗谱技术检测不锈钢晶间腐蚀提供了必要的依据。新型的304光亮不锈钢以其光洁美观的外观主要应用在大气环境中。采用恒电位开路衰减等多种电化学技术着重研究了304光亮不锈钢在含Cl-环境中的耐蚀性,结果表明,在0.01mol/L~0.6mol/L NaCl溶液及薄液膜下光亮不锈钢钝化膜的稳定性显著提高;同一浓度NaCl溶液中,光亮不锈钢点蚀击穿电位比普通不锈钢正400～600mV (SCE),显示了优异的耐蚀性能。分析认为光亮退火降低了不锈钢表面的粗糙度和减少表面贫铬现象是提高不锈钢耐蚀性的主要原因。抗菌铁素体不锈钢问世是不锈钢开发研究的另一进展,利用电化学方法、微生物学和表面分析方法研究了抗菌不锈钢在含异养菌介质中的腐蚀行为。结果表明不锈钢的腐蚀电位随异养菌新陈代谢呈现规律性地变化,抗菌处理使不锈钢在菌液中钝化膜的稳定性得到改善,点蚀敏感性降低;抗菌不锈钢表面弥散分布的ε-Cu析出相的杀菌作用,降低了异养菌的活性,减缓了异养菌对抗菌不锈钢的腐蚀,提高了抗菌不锈钢耐微生物腐蚀性能。更多还原

【Abstract】 Stainless steels are one of the most widely used eco-friendly materials. However improper fabricating processes and employing conditions will cause various types of corrosion, among which intergranular corrosion is one of the most hazardous forms. While there are still no rapid, quantitative, non-destructive and versatile in situ methods competent for intergranular corrosion sensitivity detection up to now. In recent years as the importance of environment protection are more and more valued, diversified functional stainless steels began to come out, but still there are few reports concerning about corrosion of functional stainless steels in specified environments. This paper is focusing on corrosion problems in application of traditional stainless steel, new functional 304 bright-annealed stainless steel and 430 antibacterial stainless steel developed and manufactured by Taiyuan Iron and Steel Group Co. Ltd.In order to develop intergranular corrosion detection methods, electrochemical tests and SEM are used to study sensitive temperatures of intergranular corrosion, and also the procedure of initiation and development of intergranular corrosion. Electrochemical impedance spectroscopy (EIS) technique is applied to detect intergranular corrosion and equivalent circuit for intergranular corrosion is studied and corresponding parameters are decided accordingly. The relativity between equivalent circuit parameters and intergranular corrosion sensitivity is discussed. The results show that the intergranular corrosion sensitive temperatures between austenitic stainless steel and ferrite stainless steel are different from each other. Therefore in order to avoid unqualified products, the sensitizing heat-treatment system for the intergranular corrosion sensitivity examination should change according to various steel types. During EPR polarization in reactivation region EIS diagrams of both solution-annealed and sensitized 304 stainless steels present feature of double capacitance resistance arc and impedance modulus of sensitized stainless steel is one order of magnitude less than that of solution-annealed one at low frequencies, which shows that intergranular corrosion happens on sensitized stainless steel. Electrochemical equivalent circuit parameters such as Cc and Cd increase with severity of intergranular corrosion of sensitized stainless steel, whereas reverse situation happens to Rt, as is somewhat relative to occurrence and development of intergranular corrosion. The results obtained above provide the knowledge base for更多还原