钛酸酯改性硅烷涂层优化及其对5056铝箔耐蚀性能的影响

Optimization of Titanate Modified Silane Coatings and Their Effect on Corrosion Resistance of 5056 Aluminum Foils

采用钛酸酯改性硅烷偶联剂作为封孔剂,利用浸渍提拉法对5056铝箔阳极氧化膜进行封孔处理,研究了偶联剂溶质配比、浸渍时间、烘干时间和温度对铝箔耐蚀性能的影响,并探讨了钛酸酯对涂层耐蚀性提升的机理。结果表明,经钛酸酯改性硅烷偶联剂封孔后,阳极氧化膜层表面形成了连续致密的复合膜,膜层厚度在铝箔双表面均匀一致;当溶质中Ti∶Si=0.3∶5.7时,复合涂层耐蚀性最优;其重铬酸钾耐蚀点滴时间在19℃持续30 min,自腐蚀电流密度低至7.42 n A/cm^(2),盐雾实验16 d表面出现腐蚀斑点,远高于单一硅烷涂层对应的9 min、1.81×10^(2)nA/cm^(2)、盐雾8 d性能参数。这是由于硅烷/钛酸酯复合涂层形成由钛酸酯框架和硅烷分子填充物所构成的空间网络结构,在多孔膜表面形成致密覆盖层,减缓腐蚀介质渗入,进而促进耐蚀性提升。

The anodic oxidized 5056 aluminum foil is post sealed with titanate modified silane cou-pling agent by dip coating method.The effect of solute ratio,dipping duration,drying time and tempera-ture on the foil corrosion resistance is systematically studied.The mechanism related with the enhance-ment of corrosion resistance induced by the titanate additives is discussed.The results show that a con-tinuous and dense composite film is formed on the surface of anodic coating after sealing with the tita-nate modified silane coupling agent.The film thickness is uniform on both surfaces of the aluminum foil.The best corrosion resistance is achieved with a composite film formed in the sealing bath with the ratio of Ti to Si=0.3 to 5.7.The coating after sealing exhibits 30 min before the occurrence of coating damage by K2Cr 2 O7solution drop testing at 19℃,free-corrosion current density of 7.42 nA/cm^(2),and salt spray test up to 16 d,being higher than those of the single silane coating of 9 min,1.81×10^(2)nA/cm^(2),and 8 d,re-spectively.This is attributed to the spatial network structure of the composite film formed by the titanate stereo framework and the silane additives.This develops dense film on the anodic coatings to retard the corrosive species,and thus promotes the corrosion resistance.