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采用电化学阻抗谱(EIS)研究了3．5％(质量分数)NaCl溶液中外加磁场对Ni基电磁屏蔽涂层单、双层体系保护性能的影响,并采用体视显微镜与扫描电子显微镜对浸泡后涂层的表面及截面形貌特征进行了观察.结果表明,单层Ni基涂层体系下,磁场的作用表现为阻滞了溶液的扩散,使得其低频阻抗模值|Z|0．01 Hz随浸泡时间的增加下降速度减缓,这是由于磁场使涂层中 Ni 颗粒重新排布,减少了涂层内缺陷；对于电磁屏蔽涂层/丙烯酸聚氨酯清漆双层体系,EIS结果表明外加磁场使涂层|Z|0．01 Hz下降更快,而磁场方向对|Z|0．01 Hz的变化规律无明显影响.这说明尽管磁场优化了底漆中Ni颗粒在涂层中的分布,提高了电磁屏蔽底漆的保护性,但是对于丙烯酸聚氨酯面漆的失效过程,磁场对电解质扩散的加速作用占主导地位,二者叠加总体来说磁场加速了双层涂层体系腐蚀过程.

Electrochemical impedance spectroscopy (EIS)is applied to research the protection performance of sin-gle and double system of Ni/acrylic polyurethane electromagnetic shielding coating which influenced by external magnetic field in 3.5wt% NaCl solution.The stereo microscope and SEM are adopted to represent the surface of Ni/Acrylic polyurethane electromagnetic shielding coating and cross-section morphology characteristics after soaking.The results suggest that magnetic field slows down the performance of the solution diffusion in single Ni-based coating,which delays the decrease of the low frequency impedance|Z|0.01 Hz with the increase of im-mersion time.It shows that the magnetic field makes Ni particles rearrange inside the coating and reducing the inner coating defects.As for the double-layer system of Ni/Acrylic polyurethane electromagnetic shielding coat-ing,EIS results show that the applied magnetic field makes the low frequency impedance|Z|0.01 Hz fall faster, however,the magnetic field direction has no obvious effect on the low frequency impedance|Z|0.01 Hz .Analysis shows that magnetic field optimize the distribution of Ni in coating and improves the corrosion resistance of e-lectromagnetic shielding coating.But for the failure process of topcoat (Acrylic polyurethane),the magnetic field plays a main role in accelerating the diffusion of electrolyte.In summary,the magnetic field accelerates the corrosion process of double coating system.