Zhang Yan, Tian Jingwei, Zhong Jing, Shi Xianming
Laboratory of Corrosion Science & Electrochemical Engineering, Civil and Environmental Engineering , Washington State University , Pullman , Washington 99164 , United States.
School of Civil Engineering , Harbin Institute of Technology , Harbin , 150001 China.
ACS Nano. 2018 Oct 23;12(10):10189-10200. doi: 10.1021/acsnano.8b05183. Epub 2018 Sep 17.
The rigorous organic and inorganic laminated structure of nacre has been developed by millions of years of biological evolution against various external impacts, including mechanical loadings and chemical attacks. Nacre-biomimetic materials have been recognized as an effective strategy to achieve high strength and toughness simultaneously. However, the understanding of nacre-like structure from the perspective of corrosion protection is still very limited. This work investigates the anticorrosion performance of nacre-biomimetic GO/epoxy (NBGE) coatings with alternating layers. Potentiodynamic polarization measurements indicated that the corrosion rate of steel protected by the NBGE coating with 5 layers of GO and 6 layers of epoxy (5NBGE) and a total thickness of 17 μm was 20 times slower than that of steel under the pure epoxy coating twice as thick in 3.5 wt % NaCl solution. Electrochemical impedance spectroscopy measurements revealed the importance and functions of the GO layers in NBGE coatings. The 5NBGE coating exhibited better performance than carbon-based nanoparticle/epoxy mixed coatings. The superior anticorrosion performance of the NB5G6E coating was supported by photographic observations, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and chloride diffusion measurements. The strong cross-linking layer-by-layer structure of NBGE coatings was proved by Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and X-ray diffraction analyses. The anticorrosion mechanism of the NBGE coatings was interpreted by the mitigation of chemical reactions occurring at the steel-coating interface due to the restricted intrusion of O, HO, and Cl through the reduced pores and defects by the intercalated GO layers in the coatings.
珍珠层严谨的有机和无机层状结构是经过数百万年生物进化形成的，以抵御包括机械载荷和化学侵蚀在内的各种外部冲击。仿珍珠层材料已被公认为是一种同时实现高强度和高韧性的有效策略。然而，从腐蚀防护角度对类珍珠层结构的理解仍然非常有限。本工作研究了具有交替层的仿珍珠层氧化石墨烯/环氧树脂（NBGE）涂层的防腐性能。动电位极化测量表明，在3.5 wt% NaCl溶液中，由5层氧化石墨烯和6层环氧树脂（5NBGE）组成、总厚度为17μm的NBGE涂层保护的钢的腐蚀速率比两倍厚度的纯环氧树脂涂层保护的钢慢20倍。电化学阻抗谱测量揭示了氧化石墨烯层在NBGE涂层中的重要性和作用。5NBGE涂层表现出比碳基纳米颗粒/环氧树脂混合涂层更好的性能。通过摄影观察、扫描电子显微镜、能量色散X射线光谱和氯化物扩散测量，证实了5NBGE涂层具有优异的防腐性能。傅里叶变换红外光谱、X射线光电子能谱和X射线衍射分析证明了NBGE涂层具有强逐层交联结构。由于涂层中插层的氧化石墨烯层减少了孔隙和缺陷，限制了O、HO和Cl的侵入，从而减轻了钢-涂层界面处发生的化学反应，以此解释了NBGE涂层的防腐机理。
