1050鋁合金在含鋁離子鹽酸溶液中的電解粗化行為之研究

The Electrograining Behavior of 1050 Aluminum Alloys in Aluminum Chloride Added Hydrochloric Acid Solutions

1050鋁合金是被用來製造預塗裝感光版的材料，其製造的程序包括利用交流電源進行電解粗化處理以提高水的持有性和後續感光塗層的附著性。本研究針對印刷用1050鋁合金進行電解粗化，藉由蝕孔形貌觀察以及表面粗糙度分析，來瞭解粗化時蝕孔衍生成長的行為，並得知氯化鋁添加的效應。研究結果發現氯化鋁添加大幅改變1050鋁合金的電解粗化行為，鹽酸溶液添加鋁離子後在低電流下（< 14 A/dm2）不產生電解粗化的表面形貌，卻傾向產生電解腐蝕（etching），而採高電流（> 50 A/dm2）電解粗化卻明顯產生較少的蝕孔。進一步實驗與理論分析的結果得知氯化鋁添加在電解液形成電蝕形貌的主因來自於氯離子而非鋁離子的效應，此可解釋為當電解液氯離子濃度提高，對鋁材鈍化膜侵蝕性過強，產生過多的起始空洞，因此無法產生適量的孔洞且深入鋁板產生半圓形的粗化蝕孔；至於在高電流電解產生較少的孔洞則可歸因於較多的鋁離子產生過厚的腐蝕膜阻礙了蝕孔的產生。為去除過厚腐蝕膜造成的影響，利用間歇式送電的方式，在送電休止的時間去除腐蝕膜，可以得到正常的電解粗化表面。

1050 aluminum alloys are generally used to fabricate pre-sensitized plates (PS plates) for printing. For practical applications, it is necessary to improve the adhesion of subsequent photosensitive coatings and to enhance the water retention properties of the alloy by increasing its total surface area. The fabrication process involves roughening or electrograining of the aluminum alloy in an acid solution via an AC power supply. The study focused on the electrograining behavior of 1050 aluminum alloy samples in aluminum chloride added hydrochloric acid solutions. The surface morphology of the sample was observed with scanning electron microscope, and the surface properties were analyzed to help understand the growth of grains and the effect of aluminum chloride addition. The results demonstrated that the addition of aluminum chloride greatly changed the electrograining behavior of the aluminum alloy. With aluminum chloride, the electrolysis at low current densities (< 14 A/dm2) tended to result in an etched morphology instead of a grained one on the samples. Comparing with the samples electrograined in the solution without aluminum chloride, the samples processed at a higher current density (> 50 A/dm2) exhibited less pits. Furthermore, chloride ion instead of aluminum ion was confirmed to contribute the difference during the early stage of graining. It was speculated that the passive film on the aluminum sample was more easily attacked by the solution with more chloride ions, and there were thus too many initial pits to develop a grained surface. At high current densities, the aluminum ions in the electrolyte seemed to form a thick film to deter pit initiation. Intermittent currents were applied to remove the thick film, and a normal electrograined surface was obtained.