ULTRA-ALKALINE CORROSION RESISTANCE COATINGS VIA ELECTROPHORETIC SOL-GEL PROCESSING

传统的溶胶-凝胶工艺是将基体浸入溶胶溶液中，然后进行热处理，形成致密的复合膜，而采用一种新的溶胶-凝胶工艺，在室温下进行紫外线（UV）照射，以提高铝的耐碱性腐蚀性能。结果表明，室温下紫外光辐照制备的溶胶-凝胶膜的耐碱性是573 K下加热制备的复合膜的2.4 ~ 2.6倍，其耐碱性的提高是由于光激发消除了残余有机物，使涂层致密化的原因。辐照膜的高耐碱性是由于在复合膜中形成了致密的涂层和反应物在NaOH溶液渗透过程中的反复制备和溶解所引起的自修复作用。其次，研究了溶胶-凝胶电泳沉积法制备厚涂层的工艺。涂层厚度随外加电压和时间的增加而增加。所产生的涂层比在浸涂中获得的涂层更厚且更致密。

Instead of conventional sol-gel process in which the heat treatment is performed for forming dense composite film after the dipping-withdrawing of substrate into the sol solution, a new sol-gel process incorporated with an ultraviolet(UV) -irradiation at an ambient temperature have been attempted to improve the alkaline corrosion resistance of aluminum. The sol-gel film prepared by UV -irradiation at an ambient temperature indicated the alkaline corrosion resistance superior in the range of 2.4 times to 2.6 times to that of the conventional composite film heated at 573K.The improvement of alkaline corrosion resistance was responsible for the densification of coating layer due to the elimination of residual organics induced by photo-exixitation. The high alkaline corrosion resistance of the irradiated film may be attributed to the formation of dense coating layer and the self repairing action caused by a repetition for preparation and dissolution of the reactant in the penetrating path of NaOH solution into the composite film. Next, the preparation of thick coating film by the sol-gel electrophoretic deposition method have been investigated. The thickness of coating layer was observed to increased with increasing applied voltage and time. The coating layer produced were thicker and more dense than those obtained in dip-coating.