| 摘要: | 本研究探討不同電蝕條件與不同鋁箔製造條件，對於鋁電解電容器用陽極鋁箔之影響。本研究區分為三部份，首先針對高壓用陽極鋁箔之直流電蝕進行研究，接下來探討電流條件對低壓用陽極鋁箔之影響，最後著重於低壓陽極鋁箔之製造流程與其電蝕結果的相關討論。 第一部份: 此部分主要以研究高壓540VF陽極鋁箔為主，分別改變電蝕液成份、溫度、電流密度等條件，探討鋁箔經電化學蝕刻後，其腐蝕組織與形貌對於表面積增加率的影響。首先利用恆電位儀觀察在不同電蝕參數下，電位-時間關係圖。藉由電位、時間的變化推測腐蝕反應進行時的情形。接下來依照不同探討主題來控制不同的電蝕參數，實際進行陽極鋁箔的電化學蝕刻，再按照EIAJ的規範對電蝕鋁箔做540VF的化成處理，並分別量測其靜電容量、重量損失率、引張折曲強度。最後利用光學顯微鏡(OM)與電子顯微鏡(SEM)將腐蝕試片作截面、表面、皮膜複製觀察以了解腐蝕孔洞的分佈狀況。 由實驗結果得知，適當的硫酸添加量，有較適合tunnel蝕孔形成的離子濃度與腐蝕電位，也可以得到較佳的腐蝕組織與靜電容量。而改變電流密度方面，提供的電流密度越大雖有較大的腐蝕電流，但實際用於腐蝕的電量卻較少，所以鋁箔重量損失率較小。至於改變溫度的實驗，溫度越高Cl-離子的擴散速率也越快，重量損失率也越大。而要得到較適合的腐蝕組織，也都要控制較適合的電流密度與電蝕液溫度。 第二部份: 此部份著重於電蝕過程中不同的電流密度及電蝕頻率對於電化學蝕刻後陽極鋁箔的腐蝕組織及靜電容量的影響，藉此精確掌握此二參數對電蝕工程所造成之變化。另外，本實驗透過電化學分析儀的輔助，可清楚瞭解在整個電蝕過程中電位、電流變化的情形，以及孔洞的生成與成長現象，提供更多學理上的瞭解與證明，以期能對整個鋁電解電容器之研究有顯著的助益。 試片經過不同電流密度及電蝕頻率的蝕刻後，先量測試片的重量損失率，隨後將試片依EIAJ規範進行20VF的化成處理，並量測其靜電容量值。利用光學顯微鏡及掃描式電子顯微鏡來觀察鋁箔截面腐蝕深度及表面蝕孔分布的型態。藉由這些方法來比較在不同的電流密度及電蝕頻率條件下所造成的腐蝕組織對最後靜電容量的影響。在電化學分析部份，藉由恆電位儀來觀察在不同的電流密度及電蝕頻率條件下電蝕過程中電位與電流變化的情形。藉由電位或是電流的變化，可判斷在各種條件下腐蝕反應進行情形。 由實驗結果得知：電蝕頻率越高，造成鋁的溶解量越少，形成的孔洞較小但數量較多，而靜電容量值與電蝕頻率並非呈現絕對相關的趨勢；電流密度越高，造成鋁溶解量越多，靜電容量值會有上升趨勢，此外電流密度越高，表面生成的蝕孔也會變多。 第三部份: 本章探討不同製程參數，分別為不同均質化、冷加工量、熱滾軋及安定化處理(stabilizing treatment)等製程，針對於不同製程下所生產之鋁箔進行電化學蝕刻之相關研究。首先利用ICP-AES來分析低壓陽極箔內所含之微量元素，確定其元素及含量，以便後續之研究，並透過極圖分析(pole figure)及穿透式電子顯微鏡(TEM)，了解微鋁箔的集合組織和微組織結構。在電化學蝕刻之後，再按照EIAJ的規範對電蝕箔做20VF的化成處理，並量測其靜電容量及重量損失率。利用光學顯微鏡(OM)及掃描式電子顯微鏡(SEM)，來觀察電蝕箔之截面腐蝕形態及表面的腐蝕孔洞分佈情形。藉由這些分析方法，來比較不同製程參數所造成之腐蝕組織，對鋁電解電容器用低壓陽極箔之靜電容量的影響。 由實驗得知:在實施不同冷加工量的鋁箔，靜電容量差異不大，其中以90%最佳；而均質化和熱滾軋溫度的提升，可使孔洞分布均勻，減少粗大的孔洞產生，進而增加靜電容量；在安定化處理方面，適當的安定化可使集中的差排消解，得到較佳的差排分佈，經安定化處理其靜電容量都比未安定化處理提昇許多。 This work studies the effects of etching parameters and foil manufacturing process of the aluminum foils used in electrolytic capacitors. There are three parts of this survey showed as below : Part1 : This part focus on the survey of 540VF aluminum foil primarily. By changing concentration, current density and etching temperature. We investigated the effects of etching morphology on the surface increment. This experiment first used potentiostat to observe the relationship between potential-time under different etching parameters. Thus we could predict the reaction during etching. According to the selected parameters of electrochemical etching, the aluminum foils have been etched, and the capacitance was measured under EIAJ specifications. For surface, oxide replicas and cross section morphology studies, the samples were examined in the SEM, SEM and OM respectively From the experiments, it was found that there was a proper sulfuric and hydrochloric acid concentration for tunnel etching. At this concentration we could get a fine microstructure for increasing capacitance. Phosphoric acid could grow a passive film, which protected aluminum from Cl- corrosion. Although high current density had large corrosive current, the current efficiency was bad too. Increased etching temperature could accelerate the diffusion of Cl-. There also had proper current density and temperature for etching process. Part2 : This part studies the effects of current frequency and current density on etching morphology, microstructure and static capacity of the aluminum foils used in electrolytic capacitors. The behavior associated with electrochemical etching during an anodic half cycle was investigated by a potentiostat. The oxide covering of the anode, which protected aluminum from etching, thickened as the frequency increased. Increasing the current density inhibit the passing of chlorine ions through the passive cover. The static capacity increased to 70 uF/cm2 with 20 VF forming voltage by optimization the etching parameters used herein this work. Part3 : First of all, the chemical compositions of high purity aluminum foils were determined before etching by using the analysis of ICP-AES. This research will examine different parameter of procedure such as different homogenization treatment, cold rolling, hot rolling, and stabilizing treatment. The texture of Al-foil was analyzed by pole figure, and microstructure observation was used by transmission electron microscope (TEM).After electrochemical etching, we forming according to EIAJ standard and measures its capacitance and rate of weight loss. To discuss the effect of capacitance caused by etched structure, the morphology of etched surface and cross section was observed by scanning electron microscope (SEM) and optical microscope (OM).From the observation of etched microstructure, the effect of procedure factors on the etching behavior of high purity aluminum foils could be studied in details. In the results of experiment, it was found that the capacitance is similar under different cold-rolled. When the temperature of homogenization treatment and hot-rolled was raised, the capacitance will be increase. And then it had fine pit which distributed uniform .The fitting of stabilizing treatment could scatter dislocation. And the sample of stabilizing treatment was carry out , it had better capacitance than not stabilizing treatment. |
