Study on the Electrochemical Deposition of LDH Coating on the Surface of Mg-1.5Zn-1.0Gd Alloy after Solid Solution and Its Corrosion Resistance

层状双氢氧化物(Layered Double Hydroxides, LDHs)具有优异的屏蔽性能和离子交换性能，能够有效隔绝镁合金与腐蚀介质的接触，阻止或减缓腐蚀反应的发生。本文采用电化学沉积法在固溶后Mg-1.5Zn-1.0Gd合金表面制备LDH涂层，借助扫描电子显微镜(SEM)、能谱仪(EDS)、X射线衍射仪(XRD)、傅里叶红外吸收光谱仪(FT-IR)以及电化学工作站等多种手段，详细探究了不同电沉积电压对涂层的微观结构及其耐腐蚀性的影响。实验结果表明，在−1.4 V电沉积电压下，LDH涂层表面裂纹相对均匀平整，有少量的小颗粒，与基体结合良好。相比于−1.3 V及−1.35 V电沉积电压下的LDH涂层，−1.4 V时的LDH涂层的LDH相的峰面积较大，α-Mg的峰强度较小，LDH涂层更厚。当电沉积电压为−1.4 V时，其腐蚀电位为正，自腐蚀电流密度最小，为8.96 × 10−7 A·cm−2，且Rct值最大，低频区(f Layered Double Hydroxides (LDHs) have excellent shielding performance and ion exchange performance. They can effectively isolate magnesium alloys from the contact of corrosive media and prevent or slow down the occurrence of corrosion reactions. In this paper, LDH coatings were prepared on the surface of Mg-1.5Zn-1.0Gd alloy after solution treatment by electrochemical deposition method. With the help of various means such as scanning electron microscope (SEM), energy dispersive spectrometer (EDS), X-ray diffractometer (XRD), Fourier Fourier infrared absorption spectrometer (FT-IR), and electrochemical workstation. The influence of different electrodeposition voltages on the microstructure and corrosion resistance of the coating was explored in detail. The experimental results show that at an electrodeposition voltage of −1.4 V, the surface cracks of the LDH coating are relatively uniform and smooth, with a small number of small particles, and they bond well with the substrate. Compared with the LDH coatings under the electrodeposition voltages of −1.3 V and −1.35 V, the peak area of the LDH phase in the LDH coating at −1.4 V is larger, the peak intensity of α-Mg is smaller, and the LDH coating is thicker. When the electrodeposition voltage is −1.4 V, its corrosion potential is positive, the self-corrosion current density is the smallest, which is 8.96 × 10−7 A·cm−2, and the Rct value is the largest. The AC impedance modulus value in the low-frequency region (f < 1 Hz) is the largest. After soaking in 3.5 wt.% NaCl solution, the surface corrosion degree of the LDH coating at −1.4 V was relatively mild, and the pH value and hydrogen evolution amount were significantly smaller, showing excellent corrosion resistance. Therefore, through continuous optimization of the deposition process and in-depth exploration of the coating formation mechanism, it is expected to further enhance the application performance and market competitiveness of this alloy material in fields such as aerospace, automotive manufacturing, and electronic information.