Effect of modified MgAl-LDH coating on corrosion resistance and friction properties of aluminum alloy

• Published in: Chinese journal of chemical engineering 2023-11, Vol.63 (11), p.81-95
• Main Authors: Wang, Zuokai, Xiong, Zhuangzhuang, Li, Xinxin, Wang, Di, Wang, Yuelin, Wu, Shangcheng, Ying, Lixia, Zhideng, Wang, Wang, Guixiang
• Format: Article
• Language: English
• Subjects: Anodizing; Corrosion resistance; Layered double hydroxide; Superhydrophobic; Tribological properties
• ISSN: 1004-9541
• DOI: 10.1016/j.cjche.2023.05.013

Mg-Al layered double hydroxide (MgAl-LDH) was prepared on the surface of anodic alumina by in-situ growth method. Firstly, the prepared MgAl-LDH film was intercalated with corrosion inhibitor thiourea under acidic conditions, and then the surface was hydrophobically treated in stearic acid ethanol solution. The modified film with synergistic action of corrosion inhibitor and hydrophobic layer was prepared, which improved the corrosion resistance of the substrate and reduced the friction coefficient. [Display omitted] The in-situ growing approach was utilized in this article to construct the magnesium-aluminum layered double hydroxide (MgAl-LDH) film on the surface of a 1060 aluminum anodized film. To improve the corrosion resistance and friction qualities of aluminum alloy, the MgAl-LDH coating was treated using stearic acid (SA) and thiourea (TU). The aluminum substrate and anodized aluminum film layer corroded to varying degrees after 24 h of immersion in 3.5% (mass) NaCl solution, while the modified hydrotalcite film layer continued to exhibit the same microscopic morphology even after being immersed for 7 d. The results show that the synergistic action of thiourea and stearic acid can effectively improve the corrosion resistance of the MgAl-LDH substrate. The tribological testing reveals that the hydrotalcite film layer and the modified film layer lowered the friction coefficient of the anodized aluminum surface substantially. The results of the simulations and experiments demonstrate that SA forms the dense LDH-TU interlayer film layer by exchanging NO3– ions between TU layers on the one hand and the LDH-SA film layer by adsorption on the surface of LDH on the other. Together, these two processes create LDH-TU-SA, which can significantly increase the substrate's corrosion resistance. This synergistically modified superhydrophobic and retardant hydrotalcite film layer offers a novel approach to the investigation of wear reduction and corrosion protection on the surface of aluminum and its alloys.