| 摘要: | 鋁的陽極氧化機制複雜，許多學者對於孔洞的形成原因提出了焦耳熱模型、電場輔助溶解模型、應力驅使氧化物流動模型、水解離模型以及氧氣泡模具模型…等理論。其中，氧氣泡模具理論為孔道由下而上突破氧化層為主的機制，並且氧氣泡理論也能合理解釋多孔陽極氧化鋁在鋁基地表面所形成的半球型結構。本研究探討鋁合金硫酸陽極氧化皮膜表面上的初始孔洞形成並對氧氣泡在氧化鋁層中所受的電場應力進行量化。最後，根據計算而得到的電場應力結果，對文獻中未提及的氧氣泡在氧化層中突破表面的機制進行說明。另外，本研究也對電流密度和電解液溫度對5N純鋁與AA1050陽極氧化的影響以及變形對純鋁、AA7005-T7、AA7075-T5、AA7075-T6和AA7075-T73的陽極氧化行為、微結構變化、抗腐蝕能力與光學性質進行實驗。
本研究共分三部分，第一部份的實驗探討硫酸陽極氧化的行為，並分別對COMSOL模擬凹槽處的電場強度、TEM觀察初始陽極氧化階段的橫截面以及氣泡介面的電場應力值進行調查；第二部分的實驗則是對5N純鋁及AA1050進行四種陽極條件(293K, 1.2 A/dm2 、283K，1.5 A/dm2、303K, 1.5 A/dm2和293K, 1.8 A/dm2)硫酸陽極實驗，量測陽極時的電壓與時間的關係(V-t曲線)、陽極皮膜的孔洞形貌與特徵；另外，實驗也包括不同變形量(0%、30%、50%及70%)對5N純鋁陽極氧化行為的影響；實驗的第三部份將對AA7005-T7、AA7075-T5、AA7075-T6和AA7075-T73的試片進行冷輥軋變形(0%、5%和10%)後，對其微結構、物理性質、抗腐蝕能力與光學性質進行研究。測試結果顯示，氧氣泡在電場下受擠壓應力可達31.8 MPa；氫含量有助於氧氣泡的成長；變形會影響陽極孔洞的生長與皮膜的品質與降低材料的抗腐蝕能力。
;The pore formation in anodization processes was complex and draw many scholars to present different models for discussion; mainly concerning the transient development of anodic alumina oxide film (AAO film). These models included “Joule heat”, “Field-assisted dissolution”, “Water-dissolution” and “Stress driven oxide flow”, etc. Recently, a model called “Oxygen bubble mould effect” was presented and published. It described that oxygen bubble could generate the hemi spherical structure on anodic alumina matrix.
This study proposed a new interpretation about the pore formation in the anodic alumina film with sulfuric acid solution. We calculated the electric stresses acting on oxygen bubble interface, and describde how the oxygen bubble evolved during the anodizing process. Effects of different anodizing parameters, such as current densities and electrolytic temperatures, on anodic behavior were further discussed. All discussions were based upon experimental results; including the microstructures of AAO film, voltage-time curve, anti-corrosion and optical properties of different 7000 series aluminum alloys. Processing parameters included degree of deformation (0%, 5% and 10%) and different heat treatments (T5, T6, T7 and T73).
This study used a software called “COMSOL” to simulate electrical strength around a cavity. Cross sections of anodized samples were observed by transmission microscope. The electric stresses acting on the interface of an oxygen bubble was computed and highlight its magnitude under different parameters (293K, 1.2 A/dm2、283K，1.5 A/dm2、303K, 1.5 A/dm2 and 293K, 1.8 A/dm2). The voltage-time (V-T) curveused to distinguish t different growing stages. Experiments were also conducte to study the microstructure, physical properties, anti-corrosion and optical properties of AA7005-T7、AA7075-T5、AA7075-T6 and AA7075-T73 samples affected by different degress of cold rolling. |
