高纳米SiO_2含量对环氧清漆耐腐蚀性影响研究

EFFECT OF HIGH NANO-SiO_2 CONTENT ON CORROSION RESISTANCE OF EPOXY VARNISH

研究了含量为10%和30%的硅烷偶联剂处理前后的纳米SiO2对涂覆LY12铝合金上的环氧清漆耐腐蚀性能的影响.扫描电镜形貌表明,添加未处理的纳米SiO2,涂层树脂中的SiO2以团聚体的状态存在,经过硅烷偶联剂处理的纳米SiO2与树脂呈一体状态.3.5%NaCl溶液中浸泡1200小时的电化学阻抗谱(EIS)的研究表明,加入10%未处理纳米SiO2的清漆浸泡24小时后出现不明显的第二个时间常数,但含量为30%的清漆则由于团聚的效应在浸泡初期比前者出现更明显的第二个时间常数;添加10%硅烷偶联剂处理后纳米SiO2增强了清漆的耐腐蚀性,添加30%硅烷偶联剂处理后纳米SiO2的清漆具有最好的耐腐蚀性,两者在整个浸泡过程中体现一个时间常数的特征.

Nano-SiOz,as one pigment for an epoxy vanish,was pretreated by 10% and 30% γ-glycldylo- xipropyhrimethoxysilane. Thenceforth effect of the treatment on corrosion resistance of the epoxy varnish on LY12 aluminum alloy was investigated. SEM results showed that the un-treated nano-SiO2 presented as conglomeration in the epoxy varnish, while the treated ones presented as dispersives in the epoxy varnish. EIS（ Electrochemical Impedance Spectrum）was obtained for the epoxy varnish without and with nano- SiO2 immersed in 3.5% NaCl solution for 1200 h, and the relevant fitting parameters of equivalent circuit for EIS were compared. A second time constant occurred for the varnish with addition of 10% unteated SiO2 after 24 h of immersion, while for 30% untreated SiO2 , the second time constant was more distinct than the former, which was due to the agglomeration of nano-particles. The addition of 10% silane treated nano-SiO2 improved the corrosion resistance of epoxy varnish and epoxy varnish with 50% silane treated nano-SiO2 has the highest corrosion resistance. The EIS of the two showed only one time constant.