【作者】 张正；

【导师】 宋诗哲；

【作者基本信息】 天津大学 ， 应用化学， 2007， 博士

【摘要】 在国民经济建设和国防安全中,飞行器具有极其重要的作用。作为制造飞行器的重要结构材料,高强铝合金的腐蚀直接影响着飞行器的服役寿命和飞行安全。飞行器用铝合金大气腐蚀检测的研究工作,对于飞行器延寿,腐蚀损伤检修和材料安全性评估等均具有重要的意义。高强铝合金大气腐蚀的本质是表面薄液膜覆盖下的电化学腐蚀。因此,本文主要针对高强铝合金大气腐蚀的电化学检测开展研究。大气环境中金属材料表面形成薄液膜的稳定性和连续性都很差,很多电化学方法都不能适用于高强铝合金大气腐蚀检测。电化学噪声(EN)技术作为一种原位无损的电化学测试技术,特别适用于金属材料局部腐蚀的研究。而且所需测试设备简单并对被测体系稳定性要求低,适合用于金属材料腐蚀现场检测。因此,本文提出了以EN技术为基础的铝合金大气腐蚀现场检测技术,从电极系统设计制作、测试方法确定、数据解析、现场用EN检测仪设计及现场检测系统构建等方面开展了工作。模拟实验结果表明所构建的现场检测系统能够实现铝合金大气腐蚀的检测,实验数据也充分反映了表面薄液膜变化对铝合金腐蚀的影响。应用所构建的铝合金大气腐蚀现场检测系统,研究了模拟近海海洋大气及工业污染大气环境中LY12CZ和LC4CS铝合金的腐蚀行为。探讨了污染潮湿大气环境中Cl—、NO3—和SO42—对两种铝合金腐蚀行为的影响。结果表明:NO3—和Cl—是影响铝合金腐蚀形态的主要因素,三种阴离子同时存在对铝合金的大气腐蚀会形成复杂的协同作用,其影响并非单一离子影响力的简单叠加。应力腐蚀开裂是对高强铝合金构件安全性危害最大的一种局部腐蚀破坏形态。本文利用电化学噪声技术对LY12CZ铝合金C型环试样的应力腐蚀裂纹产生及发展过程进行了研究,初步掌握了裂纹产生过程铝合金的腐蚀电位噪声特征,提出了快速评价铝合金应力腐蚀敏感性的新方法。电化学阻抗谱(EIS)技术应用于金属材料腐蚀研究,可以获得较多关于腐蚀过程的信息。实际服役状态表面带有处理层的铝合金耐蚀性很好,但腐蚀仍然会发生,而且腐蚀发生的更加隐蔽,危害性也更大。因此,本文采用EIS技术研究了表面带处理层的铝合金腐蚀破坏过程,得到铝合金膜下腐蚀反应和表面处理层状态等信息。研究表明水分和Cl—的渗透是引发铝合金在表面处理层下发生点蚀的主要因素。更多还原

【Abstract】 Aircraft has played an important role in national economical construction and national defend security. The corrosion of high-strength aluminium alloys which are especially used as structural materials of aircraft will influence the aircraft’s active time and security directly. It is significant to study the corrosion behaviour, field detective technique and corrosion resistance evaluation of high-strength aluminium alloy. Electrochemical corrosion occurred under the thin liquid film is the essential of high-strength aluminium alloy atmospheric corrosion. In this paper, high-strength aluminium alloy atmospheric corrosion electrochemical technologies were studied.The stability and continuity of thin liquid film formed on the surface of metal in the atmospheric environment are not so friendly to be tested by some traditional electrochemical methods. Electrochemical Noise (EN) is an in-situ and nondestructive technology, which is especially suited for studying local corrosion of metal materials. EN technology also can be used in the field detective of metal atmospheric corrosion due to its simple test equipments and low stability requirement of testing system. In this paper, an aluminium alloy atmospheric corrosion field detective method based on EN technology was presented. The electrode system was designed and fractured. The testing mode, data analysis and the system used in the field were discussed. The result of simulation experiments showed that the filed detective system established was suited for detection of aluminium alloy atmospheric corrosion; the data collected were able to reflect the influence that transformation of surface thin liquid film on aluminium alloy corrosion.The field detective system was used to study the corrosion behaviors of aluminium alloy (LY12CZ and LC4CS) in simulated paralic marine atmosphere and contaminative industrial atmosphere. The influence of Cl-、NO3- and SO42- ions in contaminative humid atmospheric environment on the corrosion behaviour of aluminium alloy were discussed. The results showed that NO3-and Cl- ions were the main factors to affect the corrosion type of aluminium alloy, the influences of the three anions in corrosion process of the aluminium alloys (LY12CZ and LC4CS) were complicated synergism, not simply superposed. Stress Corrosion Crack (SCC) is the most dangerous local corrosion type to high-strength aluminium alloy structure. EN technology was used to study the SCC generation and development of LY12CZ C-ring sample. EN potential spectrum characteristics were preliminary mastered. A quick corrosion sensitivity evaluation method was introduced.Aluminium alloys with surface treatment layer usually have good corrosion resistance in the active time, but corrosion still will occur in a proper condition and even more dangerous. Electrochemical Impedance Spectrum (EIS) technology was used to study the corrosion process of aluminium alloy with surface treatment layer. Some information about corrosion reaction occurred under the layer and the state of surface treatment layer were obtained from EIS. The result showed that the penetration of water and Cl- was the main factor to induce the pitting corrosion occurred under the surface treatment layer.更多还原