面积比对Al 6061-SS 304电偶腐蚀行为的影响

Effect of Area Ratio on Galvanic Corrosion Behavior of 6061 Aluminum Alloy and 304 Stainless Steel

对30%硝酸环境中的Al 6061-SS 304电偶对开展浸泡实验和电化学实验,研究了Al 6061材料在30%硝酸环境中的电偶腐蚀现象和不同阴阳面积比对腐蚀行为的影响,借助SEM、EDS、电化学测量等方法对腐蚀前后Al 6061的表面形貌、腐蚀坑数量、电化学参数进行了测量与分析。结果表明:Al 6061耦合SS 304后,两者间的腐蚀驱动电位差达到583 mV,Al 6061作为反应阳极发生溶解腐蚀;在SEM照片中可以明显看出耦合后出现了三类电偶腐蚀现象,其中第二相粒子与铝基体耦合引起的微电偶腐蚀是腐蚀坑的主要类型。同时,阴阳面积比增加导致电偶电位减小和腐蚀电流增大,电偶电流与阴阳面积比满足定量关系式,且经K-S检验理论与实际吻合度高。

The galvanic corrosion of Al 6061-SS 304 in 30% nitric acid environment and the influence of different area ratios of cathode and anode on the corrosion process of Al 6061-SS 304 were studied by immersion and electrochemical experiments. The surface morphology, number of corrosion pits and electrochemical parameters of Al 6061 before and after corrosion were measured and analyzed by SEM, EDS and electrochemical measurement. The results show that the corrosion driving potential difference between Al 6061 and SS 304 reaches 583 mVSCE, and Al 6061 is dissolution-corroded as the reaction anode. It can be seen from SEM images that there are three kinds of galvanic corrosion phenomena after coupling, among which the micro-galvanic corrosion caused by the second phase particles coupled with the aluminum matrix is the main type of corrosion pits. Meanwhile, the increase of the area ratio of cathode and anode leads to the decrease of the galvanic potential and the increase of the corrosion current. The galvanic current and the area ratio of cathode and anode satisfy the quantitative relationship, and the theory is in good agreement with the practice by K-S test.