以复配硅烷偶联剂为基料的无铬锌铝涂层的制备及性能研究

以复配乙烯基三乙氧基硅烷(A151)、γ-缩水甘油醚氧丙基三甲氧基硅烷(KH560)水解液为粘接剂,制备了一种水性无铬锌铝涂层。通过扫描电镜(SEM)、X射线衍射仪(XRD)、能谱仪(EDS)分析了涂层及腐蚀产物的微观形貌及成分;通过傅里叶红外分析仪(FT-IR),研究了涂层的固化过程;通过盐水浸泡实验及电化学实验研究了涂层的耐蚀性能。实验结果表明:涂层主要由Al相、Zn相、AlSi₉相、Al_0.403Si_0.597相组成,其中鳞片状锌铝粉在涂层中交替层叠,延长了腐蚀介质进入金属基体的路径,起到了良好的屏蔽作用;Tafel曲线表明相较于裸钢,涂层具有更高的腐蚀电位,能够对金属基材起到良好的牺牲阳极保护作用;在3.5%NaCl溶液浸泡试验中,随着时间的延长,锌铝涂层的腐蚀产物微观形态由初期的致密针状转变为松散的多孔结构。

Preparation and Properties of Chromium-Free Zinc-Aluminum Coatings with Compound Silane Coupling Agent as Binder

A chromium-free zinc-aluminum coating was prepared by a compound vinyl triethoxysilane(A151) and γ-glycidoxypropyltrimethoxysilane(KH560) hydrolyzate as binder. The microstructure and composition of zinc-aluminum coatings and corrosion products were analyzed by SEM,EDS and XRD. The curing process of the coatings was investigated by FT-IR. The corrosion resistance of the coatings was studied by salt water immersion test and electrochemical experiment. The results showed that the coatings mainly consists of Al phase,Zn phase,AlSi9 phase and Al0. 403 Si0. 597 phase. The scaly zinc-aluminum powder is alternately laminated in the coatings,which prolongs the path of the corrosive medium into the metal matrix and plays a good shielding role. Compared with bare steel,the coatings has higher corrosion potential,which can provide good sacrificial anode protection for metal substrates.As the corrosion deepens,the microscopic morphology of the corrosion product of the zincaluminum coatings changes from a dense needle to a loose porous structure.