Dastpak Arman, Ansell Philip, Searle Justin R, Lundström Mari, Wilson Benjamin P
Hydrometallurgy and Corrosion, Department of Chemical and Metallurgical Engineering (CMET), Aalto University, P.O. Box 16200, Aalto, Espoo FI-00076, Finland.
Materials Research Centre, College of Engineering, Swansea University, Bay Campus, Crymlyn Burrow, Swansea SA1 8EN, Wales, U.K.
ACS Appl Mater Interfaces. 2021 Sep 1;13(34):41034-41045. doi: 10.1021/acsami.1c08274. Epub 2021 Aug 19.
This study presents a process for preparation of cellulose-lignin barrier coatings for hot-dip galvanized (HDG) steel by aqueous electrophoretic deposition. Initially, a solution of softwood kraft lignin and diethylene glycol monobutyl ether was used to prepare an aqueous dispersion of colloidal lignin particles (CLPs) solvent exchange. Analysis of the dispersion showed that it comprised submicron particles ( = 146 nm) with spherical morphologies and colloidal stability (ζ-potential = -40 mV). Following successful formation, the CLP dispersion was mixed with a suspension of TEMPO-oxidized cellulose nanofibers (TOCN, 1 and 2 g·L) at a fixed volumetric ratio (1:1, TOCN-CLPs), and biopolymers were deposited onto HDG steel surfaces at different potentials (0.5 and 3 V). The effects of these variables on coating formation, dry adhesion, and electrochemical properties (3.5% NaCl) were investigated. The scanning electron microscopy results showed that coalescence of CLPs occurs during the drying of composite coatings, resulting in formation of a barrier layer on HDG steel. The scanning vibrating electrode technique results demonstrated that the TOCN-CLP layers reduced the penetration of the electrolyte (3.5% NaCl) to the metal-coating interface for at least 48 h of immersion, with a more prolonged barrier performance for 3 V-deposited coatings. Additional electrochemical impedance spectroscopy studies showed that all four coatings provided increased levels of charge transfer resistance ()-compared to bare HDG steel-although coatings deposited at a higher potential (3 V) and a higher TOCN concentration provided the maximum charge transfer resistance after 15 days of immersion (13.7 0.2 kΩ·cm for HDG steel). Overall, these results highlight the potential of TOCN-CLP biopolymeric composites as a basis for sustainable corrosion protection coatings.
本研究提出了一种通过水性电泳沉积法制备用于热镀锌（HDG）钢的纤维素 - 木质素阻隔涂层的工艺。最初，使用软木硫酸盐木质素和二乙二醇单丁醚溶液通过溶剂交换制备胶体木质素颗粒（CLP）的水性分散体。对该分散体的分析表明，它由具有球形形态且具有胶体稳定性（ζ电位 = -40 mV）的亚微米颗粒（ = 146 nm）组成。成功形成后，将CLP分散体与TEMPO氧化纤维素纳米纤维（TOCN，1和2 g·L）的悬浮液以固定体积比（1:1，TOCN - CLP）混合，并在不同电位（0.5和3 V）下将生物聚合物沉积到HDG钢表面。研究了这些变量对涂层形成、干附着力和电化学性能（3.5% NaCl）的影响。扫描电子显微镜结果表明，在复合涂层干燥过程中CLP发生聚结，从而在HDG钢上形成阻隔层。扫描振动电极技术结果表明，TOCN - CLP层在至少48小时的浸泡过程中减少了电解质（3.5% NaCl）向金属 - 涂层界面的渗透，对于3 V沉积的涂层具有更长的阻隔性能。额外的电化学阻抗谱研究表明，与裸HDG钢相比，所有四种涂层的电荷转移电阻（）水平都有所提高，尽管在较高电位（3 V）和较高TOCN浓度下沉积的涂层在浸泡15天后提供了最大的电荷转移电阻（HDG钢为13.7 ± 0.2 kΩ·cm）。总体而言，这些结果突出了TOCN - CLP生物聚合物复合材料作为可持续腐蚀防护涂层基础的潜力。
