Jo Hyunbin, Lee Soomin, Kim Donghyun, Lee Junghoon
Department of Metallurgical Engineering, Pukyong National University, 45, Yongso-ro, Nam-Gu, Busan 48513, Korea.
Analysis Technical Center, Korea Institute of Ceramic Engineering and Technology, 101, Soho-ro, Jinju-si, Gyeongsangnam-do 52851, Korea.
Materials (Basel). 2020 Oct 31;13(21):4904. doi: 10.3390/ma13214904.
Sealing as a post treatment of anodized aluminum is required to enhance the corrosion resistance by filling nanopores, which allow the penetration of corrosive media toward the base aluminum. We designed a mixed sealing solution with nickel acetate and ammonium fluoride by modifying traditional nickel fluoride cold sealing. The concentration of mixed sealing solution affected the reaction rate of sealing and corrosion current density of anodized aluminum alloy. The higher concentration of mixed sealing solution improved the sealing rate, which was represented by a decrease of corrosion current density of anodized aluminum alloy. However, a mixed sealing solution with 2/3 concentration of general nickel fluoride sealing solution operated at room temperature showed the lowest corrosion current density compared to traditional methods (e.g., nickel fluoride cold sealing (NFCS) and nickel acetate hot sealing) and other mixed sealing solutions. Moreover, the mixed sealing solution with 2/3 concentration of general NFCS had a lower risk for over sealing, which increases the corrosion current density by excessive dissolution of anodic oxide. Therefore, the mixed sealing solution with optimized conditions designed in this work possibly provides a new method for enhancing the corrosion resistance of anodized aluminum alloys.
对阳极氧化铝进行后处理密封是必要的，通过填充纳米孔来提高耐腐蚀性，纳米孔会使腐蚀性介质渗透到基底铝中。我们通过改进传统的氟化镍冷封工艺，设计了一种含有醋酸镍和氟化铵的混合密封溶液。混合密封溶液的浓度会影响阳极氧化铝合金的密封反应速率和腐蚀电流密度。混合密封溶液浓度越高，密封速率越高，这表现为阳极氧化铝合金腐蚀电流密度的降低。然而，与传统方法（如氟化镍冷封（NFCS）和醋酸镍热封）及其他混合密封溶液相比，在室温下使用浓度为普通氟化镍密封溶液2/3的混合密封溶液时，其腐蚀电流密度最低。此外，浓度为普通NFCS 2/3的混合密封溶液过封风险较低，过封会因阳极氧化物过度溶解而增加腐蚀电流密度。因此，本研究中设计的优化条件下的混合密封溶液可能为提高阳极氧化铝合金的耐腐蚀性提供一种新方法。
