3-14. High throughput accelerated simulation of the corrosion failure with the multi factors in marine atmosphere environment

Li Qian*, Hongqiang Fan
Shanghai university, Shanghai 200444, P. R. China

Abstract: The pace of building a powerful marine country was seriously restricted by the corrosion problem of marine equipment and marine engineering materials in China. The corrosion process of engineering structural materials in the marine atmospheric environment is influenced by the complicated environmental factors. Devices for the corrosion test in laboratory are set up to simulate the real marine atmospheric environment and corrosion conditions and the obtained results are reliable. Due to the limitation of experimental technology and data acquisition technology, the traditional experimental device for atmospheric corrosion just can simulate the failure behavior under the condition of single factor. In addition, most of the current electrochemical tests are single, which is unsuited to the high-throughput screening research of large-scale materials.

        Based on the salt spray experiment method, this research work increases the corrosion characteristic equivalents such as the dry and wet, pollutant, rainfall, light, load and so on, develops the integrated equivalent simulation experiment device for the marine atmospheric environment corrosion (Fig. 1), and combines the composite salt spray box with the multi-channel electrochemical workstation to develop the evaluation method of equivalent accelerated simulation for atmospheric corrosion. Five hot-dip samples were used to evaluate the corrosion failure in the marine atmosphere. It was found that the traditional salt spray test needs 96 hours, the traditional electrochemical evaluation (EIS test) needs 12.5 hours, and the combination of the composite salt spray box with the multi-channel electrochemical workstation just needs 2 hours. The results for the three methods were consistent, indicating that the trial composite salt spray tank and the electrochemical work can effectively reduce the test time and improve the evaluation efficiency of corrosion failure. On the basis of salt spray experiment, the time for up to the same corrosion rate (2.442 mg cm-2 h-1) after adding dry and wet cycles was reduced from 96 hours to 52 hours, the standard deviation of noise current was increased from 2.36 ×10-8 to 1.26 ×10-7, and the change trend of noise current was more obvious. On the basis of salt spray experiment, the corrosion rate after adding industrial pollutants increases during the different service stages. These results showed that adding dry and wet or pollutants on the basis of salt spray experiment can effectively accelerate the corrosion. In addition, the developed 32 channels in-situ electrochemical testing device can test 32 samples in the meantime, and all the channels can test EIS. The efficiency of the 32 channels in-situ electrochemical testing device is 4 times higher than the commercial electrochemical workstation test. Moreover, the 32 channels are physically insulated and independent.

        The combination of the complex salt spray tank and the electrochemical workstation can perform the in-situ electrochemical rapid monitoring. 32 flux electrochemical monitoring system can realize the high-throughput in-situ electrochemical characterization of multiple samples in one kind of corrosion medium. However, there are few kinds of materials for testing, which can not provide a large number of data for genomic technology of materials. So more materials should be evaluated in our future work.
Keywords: Marine atmosphere; Multi factor coupling; Corrosion failure; High throughput

    海洋大气环境多因素耦合腐蚀的高通量模拟实验技术

李谦*, 范洪强
上海大学

摘要:海洋装备和海洋工程用材料的腐蚀问题严重制约着我国建设海洋强国的步伐。海洋工程 结构材料在海洋大气环境中腐蚀失效过程中受到多种环境因素影响。研究多环境因素耦合作用 下的失效过程更能接近实际的服役环境。由于实验技术、数据采集技术的限制，传统的大气腐 蚀实验装置只可以模拟单一因素加速条件下的失效行为。另外，现有的腐蚀电化学测试多为单通道，测试效率不高，不能满足于大规模材料的高通量筛选研究。

      本研究工作以盐雾实验方法为基础，增加干湿、污染物、降雨、光照、载荷等腐蚀特征当量，研制了海洋大气环境腐蚀的一体化等效模拟实验装置(见图 1)，并将试制的复合盐雾箱与 多通道的电化学工作站耦合联用，探索海洋大气腐蚀的等效加速模拟试验测评方法。以 5 个热 浸镀镀层样品为海洋大气腐蚀失效评估对象，发现采用传统盐雾实验需用时 96 小时，传统的电 化学评价(EIS 测试)需用时 12.5 小时，将复合盐雾箱与电化学工作站耦合联用用时 2 小时， 并且三种方法所得出的结论相一致，表明将试制的复合盐雾箱与电化学工作站耦合联用这种方 法可有效地降低测试时间，提高腐蚀失效的评估效率。在盐雾实验的基础上添加干湿循环后达 到相同腐蚀速率(2.442 mg cm-2 h-1)所需要时间由 96 小时减短到 52 小时,噪声电流标准偏差由 2.36×10-8 增加到 1.26×10-7，噪声电流变化趋势更明显。在盐雾实验的基础上添加工业污染物 后，不同服役阶段的腐蚀速率整体增加，表明在盐雾实验的基础上添加干湿或污染物均可有效 地加速腐蚀。另外，开发的 32 通道原位电化学测试装置一次性可以同时测试 32 个样品，每个 通道均可以测试 EIS，较商业化的电化学工作站测试效率提高 4 倍以上，并且 32 个通道之间是 物理绝缘，测试无相互干扰，是独立运行的。

图 1 多因素耦合腐蚀加速模拟及原位高通量电化学测试装置 

      将复合盐雾箱与电化学工作站耦合联用实现了模拟海洋大气环境多因素耦合原位电化学快 速监测，解决了传统腐蚀盐雾箱无法模拟多因素耦合作用下的腐蚀失效和不具有原位电化学快 速监测的技术问题。32 通量原位电化学监测体系实现多样品在一种介质的高通量原位电化学表 征，但是目前评价材料种类较少，不能为材料基因组技术提供大量数据，之后应对更多的材料 进行评估。

关键词:海洋大气;多因素耦合;腐蚀失效;高通量表征