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正負半週期電量對交流電解粗化鋁板表面形貌與性質之影響

Effect of Positive/Negative Charge Ratio on the Surface Morphology and Properties of AC Electrograined Aluminum Plate

摘要


本研究以電解粗化模擬器,於硝酸電解液中對1050鋁板進行電解粗化,交流電解使用波形爲方形波,頻率爲50Hz,電流密度爲15A/dm^2,改變方形波正負半週期電量之電解粗化,探討正負半週期電量對於蝕孔衍生與成長機制及腐蝕膜之間的差異性。粗化試片以SEM觀察去除腐蝕膜前後之鋁板表面蝕孔形貌,另以橫截面TEM試片觀察蝕孔形貌與腐蝕膜結構,量測表面粗糙度以解析鋁板表面粗化特徵,並配合靜電容量量測粗化後鋁板之表面積增加量,且對腐蝕膜和鋁的溶蝕量作定量分析。粗化結果顯示當T(下標a)/T(下標c)增加時,因正半週期電量增加,蝕孔會由均勻粗化之包旋蝕孔轉變成不均勻粗化的粗大圓形蝕孔,腐蝕膜結構爲層狀結構的堆積。因負半週期時間增加而腐蝕膜增厚阻礙了電解液的侵蝕,使得蝕孔持續的減少,腐蝕膜則厚實的堆積於蝕孔上。

並列摘要


1050 aluminum plate was ac electrograined in nitric acid using a flow cell. The frequency and current density of the square waveform was 50Hz and 15A/dm^2, respectively. The time ratio of anodic half cycle to cathodic half cycle, T(subscript a)/T(subscript c) was varied to investigate how the positive/negative charge ratio affects the nucleation and growth of the etch pit and the structure of the etch film. Scanning electron microscopy was employed to characterize the surface morphology of the electrograined aluminum plate before and after the removal of the etch film. Cross- sectional transmission electron microscopy was employed for revealing the detailed morphology of the etch pits and the microstructure of the etch film. The surface properties were measured on the electrograined Al plate, on which the etch film had been removed, including R(subscript a), R(subscript max), and the relative increase factor derived from the capacitance of the Al plate. Finally, the weight loss of the Al plate and the weight of the etch film formed during electrograining were measured. Experimental results indicate that the attack of the Al plate changed from uniform graining to non-uniform graining as the T(subscript a)/T(subscript c) ratio was increased. The etch film covering the etch pit exhibited a characteristic layered structure. As the T(subscript c)/T(subscript a) ratio was increased, a relatively thick etch film overlaid the Al surface and retarded the attack of the electrolyte, accordingly the areas dotted with the etch pits decreased.

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