鋁陽極氧化處理膜對氟離子之耐腐蝕研析

Study on the Corrosion Resistance of Anodically Oxidized Aluminum Coating to Fluoride Ion

本研究以6061鋁合金經陽極氧化表面處理後，採用四氟甲烷（CF4）氣體進行耐腐蝕試驗，及其後之處理層介電強度研析。其中鋁合金表面處理包含珠擊後（Ra3.5μm）陽極氧化表面處理，與表面電解拋光整平後進行12μm厚陽極氧化處理及表面整平後進行55μm厚陽極氧化處理三種。實驗以硫酸、草酸及磷酸等溶液進行陽極氧化處理，結果經表面形貌觀察以硫酸浴的孔洞約37nm、以草酸浴的孔洞約70nm，以磷酸浴的孔洞約230nm，因此以硫酸溶液處理之孔洞尺寸最為細小。所以，後段陽極氧化經採用硫酸浴處理後，再進行沸水封孔處理。將電感耦合式電漿（ICP）通入四氟甲烷氣體進行試片之蝕刻，隨時間增加其表面層介電強度值隨之降低。最後，鋁合金試片經退火處理及電感耦合式電漿蝕刻之實驗結果顯示，兩者皆加速表面處理層介電強度值下降。

This study investigated the corrosion resistance to CF4 and the dielectric strength of anodically oxidized aluminum coating. The anodically oxidized aluminum specimens were a shot peened surface （Ra 3.5 m） and aluminum coating a 12-m-thick electrochemically polished aluminum coating, and a 55-m-thick electrochemically polished aluminum coating. These specimens were anodically oxidized in three electrolytes sulfuric acid, oxalic acid, and phosphoric acid, and the respective diameters of the cylindrical holes in the resulting porous coating were 37 nm, 70 nm, and 230nm. Because the pores of the sulfuric-acid-treated specimen were the smallest, the subsequent seal treatment was easiest to conduct. Thus, the specimen oxidized in sulfuric acid was further seal-treated in boiling water. The measurement obtained during induction coupled plasma （ICP） etching with CF4 showed that the dielectric strength of the coating decreased as the etching duration decreased. Both the annealing treatment and the ICP etching of the specimen caused the dielectric strength of the coating to deteriorate.