The addition of 2,5-pyridinedicarboxylic acid (2,5-PDCA) to the Mg-Al LDH coating, which was prepared by one-step hydrothermal synthesis, had extremely enhanced the corrosion protection of AZ31 Mg alloy, although the 2,5-PDCA could not be intercalated into the interlayer spacing. The corrosion current density of 0.05 mol L⁻¹ 2,5-PDCA LDH containing LDH coating is 3.18 nA cm⁻², reduced by two orders of magnitude compared to the LDH coating without inhibitor, and the corrosion inhibition efficiency of the coating is 98.05%. The coating formed on the surface of AZ31 was peeled off from the substrate by using a mechanical method and SEM observation of the cross-section showed that the coating consisted of three different layers. The innermost layer is a thick layer that consists of Mg(OH)₂ and the intermediate layer is LDH, which is vertical to the substrate and the outmost layer is a thin but very dense deposit layer of LDH agglomerates with complexes of 2,5-PDCA and Mg. This kind of sediment/LDH/Mg(OH)₂ three-layer composite structure was accountable for the increase in the corrosion resistance of AZ31 Mg alloy.

在一步水热合成制备的Mg-Al LDH涂层中添加2,5-吡啶二甲酸(2,5-PDCA)极大地增强了AZ31镁合金的耐腐蚀性能，尽管2,5 -PDCA不能插入层间距中。^{含有0.05 mol L -1} 2,5-PDCA LDH的LDH涂层的腐蚀电流密度为3.18 nA cm ^-2，比不含缓蚀剂的LDH涂层降低了两个数量级，涂层的缓蚀效率为98.05 %。采用机械方法将AZ31表面形成的涂层从基体上剥离，SEM截面观察表明涂层由三层不同的层组成。最内层是由 Mg(OH)2 组成的厚层_如图2所示，中间层是LDH，其垂直于基底，最外层是薄而非常致密的LDH团聚体与2,5-PDCA和Mg的络合物的沉积层。这种沉积物/LDH/Mg(OH) ₂三层复合结构是AZ31镁合金耐腐蚀性能提高的原因。