中国科学院海洋研究所机构知识库

    服役于大气环境中的金属材料常暴露于太阳光照射下，研究金属材料的大气腐蚀不能忽略太阳光照的影响。到达地球表面的太阳光中，可见光占据了整个光谱较大的比例，因此研究可见光的影响更具有实际意义。本论文研究了可见光下铜的大气腐蚀行为，揭示了可见光对铜腐蚀过程的影响机制，同时针对不同酸洗液对铜失重结果的影响展开讨论，丰富了铜大气腐蚀的理论研究体系。主要研究内容如下：

（1）研究可见光辐射对铜大气腐蚀行为的影响，腐蚀产物分析结果表明：与暗态下相比，可见光照射下铜的腐蚀产物的组成并没有发生改变，氧化亚铜仍为主要的腐蚀产物，但是腐蚀产物层的微观形貌发生改变，可见光照射下铜的腐蚀产物层更加致密。可见光照射明显加速了铜的腐蚀速率，在实验暴露周期内，可见光照射下的铜的腐蚀速率约为暗态下腐蚀速率的2~3倍；

（2）研究带锈铜试样和腐蚀产物的电化学以及光电化学性质，结果表明：暗态及可见光照射下生成的带锈铜试样上的锈层对铜的腐蚀均具有抑制作用，并且这种作用随暴露时间的延长而增大，这是由致密的氧化亚铜产物层作用引起的。光电流、光电压测试表明由n型半导体性质的腐蚀产物在可见光照射下的光电效应，导致生成的光生空穴会引起基底铜发生失电子的阳极反应，进而促进铜的大气腐蚀；

（3）研究酸洗液对铜腐蚀失重结果的影响，结果表明：由于Cu⁺的歧化反应，经国际标准推荐使用的三种酸洗液处理后得到的铜试样失重结果之间存在明显的差异。盐酸洗液中的Cl⁻在清洗过程中会络合Cu⁺，从而可有效地抑制Cu⁺的歧化反应，得到相对准确的失重结果。综合考虑到实验操作的方便性及结果的准确性，推荐使用不除氧条件下的盐酸清洗液用于铜试样的腐蚀失重分析。

    Metallic materials serving in the atmospheric environments are usually exposed to solar light illumination, which affects the corrosion of metallic materials a lot and cannot be overlooked. Visible light accounts for a large proportion of the entire spectrum of solar light arriving to earth surface that gives rise to specific significance of investigating the corrosion of metallic materials under visible light illumination. In this paper, atmospheric corrosion of copper was studied under the visible light illumination, aiming at revealing the influence of visible light illumination on the corrosion behaviors and processes of copper, simultaneously researching the impact of different pickling solutions on mass losses of copper. All of the above would provide some supplementary to the theory of copper atmospheric corrosion. The main results are presented as follows:

 (1) Influence of visible light illumination on the atmospheric corrosion behavior of copper. The composition of the corrosion products did not vary over visible light illumination compared to that exposed in the dark, both in which the cuprite remained the main corrosion products phase. Nonetheless, visible light illumination affects the corrosion morphologies of copper exposed under atmospheric environments by forming more compact product layers than those formed in the dark. In addition, the atmospheric corrosion rates of copper exposed under visible light illumination are approximate 2 to 3 times that obtained in the dark, demonstrating a promotion mechanism of copper corrosion under visible light illumination.

(2) The electrochemical/photoelectrochemical properties of the corroded samples and corrosion products of copper were studied in this paper. The results suggest that the corrosion product layers on copper samples could alleviate the corrosion due to the compact cuprite layer whose protection effect would be promoted with increasing exposing time despite the visible light illumination. Furthermore, the results of photocurrent and photovoltage tests validate that the corrosion could be promoted due to the n-type semiconductor properties of corrosion products, while the photoinduced holes would be generated under the visible light illumination and oxidize copper substrate to copper ions for products generation.

(3) Effect of different pickling solutions for mass loss determination of copper. According to the comparative studies, it is found that the weight losses of copper samples obtained after the treatments with three kinds of pickling solutions recommended by the international standard are significantly different due to the disproportionation reaction of Cu⁺. The mass losses obtained by pickling the copper samples with hydrochloric acid are quite close to the true value because the chloride ions in the hydrochloric acid solution would complex with the cuprous ions to prevent the disproportionation reaction of cuprous ions during the pickling process. In view of the convenience of the operation and the accuracy, the microgravimetry method, i.e., treating samples by the undeoxygenated hydrochloric acid solution is recommended to determine the mass loss of copper.