鋁電解電容器用鋁箔之研究; A STUDY ON THE FOIL OF ALUMINUM ELECTROLYTIC CAPACITOR

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Title:	鋁電解電容器用鋁箔之研究;A STUDY ON THE FOIL OF ALUMINUM ELECTROLYTIC CAPACITOR
Authors:	陳學奇;Hsueh-Chi Chen
Contributors:	機械工程研究所
Keywords:	電容器;鋁箔;陰極箔;陽極箔;電化學腐蝕;隧道式蝕孔;capacitance;aluminum foils;cathode foils;anode foils;electric etching;tunnel
Date:	2005-12-16
Issue Date:	2009-09-21 11:32:44 (UTC+8)
Publisher:	國立中央大學圖書館
Abstract:	摘要本論文探討鋁電解電容器用鋁箔，於添加不同含量的微量元素與不同製程後，對靜電容量的影響。內容依序分成陰極箔與高、低壓陽極箔等三大部份。利用穿透式電子顯微鏡( TEM )、掃瞄式電子顯微鏡( SEM )、X–光繞射、感應耦合電漿原子放射光譜儀( ICP-AES )、金相顯微鏡( OM )及電化學分析儀(potentiontats / galvanostats for electrochemical research)等儀器進行微結構、蝕刻組織觀察，並配合電化學的分析，探討電化學舉動、蝕刻條件與靜電容量的關係。首先針對陰極箔，添加不同含量的微量元素銀，及有無安定化處理製程，其金相組織、微結構、織構所產生的變化，對於化學蝕刻所形成蝕孔的型態、大小及分佈情況等蝕刻組織的探討，進而分析對靜電容量的影響。結果發現銀添加量在0.2 wt % 以下時，會隨著含銀量的增加，有助於鋁箔基地中Al-Fe-Mn及Al-Fe-Mn-Si分散粒子的析出，而提昇表面化學蝕刻的腐蝕能力，導致陰極箔腐蝕表面積的增加，進而提高鋁電解電容器的靜電容量。但當銀含量超過0.2 wt %時，則會造成過度腐蝕產生孔合併現象，致使腐蝕表面積減少，而降低鋁電解電容器的靜電容量。結果並顯示安定化處理，能促進鋁箔再結晶的形成，於化學蝕刻後可有效增加陰極鋁箔表面積，因而有助於提升其靜電容量。其次，針對高壓陽極箔添加含量不同之微量元素鉛，並施以直流電化學蝕刻製程後，觀察分析所形成蝕刻組織，其蝕孔的型態、大小及分佈等情況，以探討其對靜電容量的影響。結果發現有邊長約1.3 μm正四方型的蝕孔產生，在蝕孔內部表面有高低不平而具規則間隔0.12 μm之波狀皺紋的表面型態。結果並顯示添加微量鉛於高純度鋁箔，能有效地使鋁箔晶粒細化，而增加晶粒的數量。此現象造成了電化學蝕刻時蝕孔數量的增加，腐蝕的表面積因而增加，促使靜電容量也隨著提高。但當鉛含量超過0.3 ppm時，其靜電容量不再增加，反而快速降低。同時，本研究也探討低壓鋁電解電容器用陽極鋁箔於添加不同銅含量，在交流電蝕後產生之腐蝕組織及靜電容量的影響。結果發現，低壓用鋁原箔經交流電蝕後之組織為海綿狀組織。隨著銅含量增加，其擴面效果及靜電容量均提昇。但是當銅含量添加超過49 ppm後，併孔現象趨於嚴重，且腐蝕界面處會由鋸齒型轉而傾向形成直線型，促使靜電容量有下降之趨勢。以定電流循環極化曲線電化學分析，得知隨著銅含量增加，電蝕量隨之加大重量損失率亦愈高。 Abstract With the addition of the trace elements and various process treatments, in this paper, the static capacity was investigated for the aluminum electrolytic capacitor of aluminum foils. The contents were divided into three parts－cathode foils, dielectric and high (low) voltage anode foils, accordingly. The microstructure and etching morphology were observed and discussed by the applications of transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-Ray Diffraction, inductively coupled plasma atomic emission spectrometer (ICP-AES), metallurgical microscope, and electrochemical analytic system. Thus, the relationships among electrochemical behaviors, electric etching conditions and static capacity could be comprehended. Firstly, the trace element of silver content was added for the cathode foils. With or without the stabilizing treatment, the variations for the metallurgical organization and microstructure were detected. After chemical etching, the form, size and distribution of etched holes were investigated so as to assess the variations of the static capacity. It was found that the silver content promoted the precipitations of Al-Fe-Mn and Al-Fe-Mn-Si, as well as enhanced etched surface. Thus, the static capacity effectively magnified. However, after the increment of silver content was up to 0.2%, the etched holes merged together due to over etching. This phenomenon caused the etched surface to lessen so as to reduce the static capacity. Also, the results showed that the stabilizing treatment could enhance re-crystallization for the aluminum foils. Therefore, the etched surface of the cathode foils effectively increased, a fact that increased the static capacity helpfully. Secondly, after the addition of lead, aluminum foils of high voltage electrolytic capacitors proceeded with D.C. chemical etching. Thus, the form, size, and distribution of etched holes were observed to analyze the influence of the static capacitance. The results showed that the etched tunnels had square cross sections about 1.3μm per side. The inner tunnel sidewalls had a rough corrugated texture with regular ripples with a periodic interval of about 0.12μm. The addition of lead to high purity aluminum foils could effectively increase the number of grains and etched holes, which enhanced the etching of the surface as well as the static capacitance. However, the experiments showed that as the incremental addition of lead reached over 0.3ppm, the static capacitance reduced rapidly. Also, in this study, different content of copper was added for the low-voltage anode foils of aluminum electrolytic capacitor. With A. C. chemical etching, the etched morphology and the influence of the static capacity were investigated. The results showed that the morphology of the low-voltage anode aluminum foils was spongy. As the content of copper increased, the expansive effect of the etched surface and the static capacity promoted. However, as the content of the copper was added over 49ppm, the phenomenon that the etched holes seriously merged together happened. Furthermore, the saw-tooth type of the etched surface boundary was inclined to be transferred to the line type, a fact that the static capacity reduced. By the electric chemical analysis of the polarised curve at fixed electric current circulation, the results showed that the more content of copper increased, the more serious extent of etching as well as the higher rate of the weight loss was obtained.
Appears in Collections:	[Graduate Institute of Mechanical Engineering] Electronic Thesis & Dissertation

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