Fouling corrosion in aluminum heat exchangers

• Published in: Chinese journal of aeronautics Vol. 28; no. 3; pp. 954 - 960
• Main Authors: Su, Jingxin, Ma, Minyu, Wang, Tianjing, Guo, Xiaomei, Hou, Liguo, Wang, Zhiping
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.06.2015
• Subjects: Aluminum; EIS; Heat exchanger; Pitting corrosion; Tafel plots; 传热效率; 扫描电子显微镜; 污垢; 法拉第定律; 电化学测量; 电化学阻抗谱; 设备腐蚀; 铝热交换器; Tafel plots; Pitting corrosion; Aluminum; Heat exchanger; EIS
• ISSN: 1000-9361
• DOI: 10.1016/j.cja.2015.02.015

Abstract Fouling deposits on aluminum heat exchanger reduce the heat transfer efficiency and cause corrosion to the apparatus. This study focuses on the corrosive behavior of aluminum cou- pons covered with a layer of artificial fouling in a humid atmosphere by their weight loss, Tafel plots, electrochemical impedance spectroscopy （EIS）, and scanning electron microscope （SEM） observations. The results reveal that chloride is one of the major elements found in the fouling which damages the passive film and initiates corrosion. The galvanic corrosion between the metal and the adjacent carbon particles accelerates the corrosive process. Furthermore, the black carbon favors the moisture uptake, and gives the dissolved oxygen greater chance to migrate through the fouling layer and form a continuous diffusive path. The corrosion rate decreasing over time is conformed to electrochemistry measurements and can be verified by Faraday＇s law. The EIS results indicate that the mechanism of corrosion can be interpreted by the pitting corrosion evolution mechanism, and that pitting was observed on the coupons by SEM after corrosive exposure.