摘要
本研究主要探討AA7XXX系鋁合金經陽極處理後之表面缺陷觀察與分析，利用微小維克氏硬度機、金相顯微鏡(OM)、雷射共軛焦、白光干涉儀以及穿透式電子顯微鏡(TEM)等設備，針對四種市面上常用AA7XXX系列鋁合金(7003、7005、7046以及7050)，在相同熱處理與陽極處理條件參數下，進行表面缺陷觀察以及分析比較，藉由本實驗找出條紋缺陷產生之原因，進而有效提升鋁合金表面光澤度。根據研究結果發現各種7XXX系列鋁合金之表面硬度值皆比AA6063鋁合金之表面硬度值來的佳，但是7XXX系列鋁合金經陽極處理後之試片表面可以觀察到有嚴重的條紋狀缺陷產生，與AA6063鋁合金試片表面比較後發現7XXX系列鋁合金的表面光澤度較差。AA7003鋁合金經陽極處理後之氧化層表面，同時具有較佳之表面硬度與氧化層表面光澤度，其表面光澤度與AA6063較為相近。AA7003鋁合金經陽極處理後可獲得氧化層厚度約10um左右，而且氧化層本身為透明層，使得基材表面的缺陷在表面氧化層形成之後仍然看的見。經分析發現陽極處理過程，除了在鋁基材表面會形成氧化層外，在處理的過程中亦會造成鋁基材表面受腐蝕的影響而產生明顯的高低起伏造成有條紋狀之缺陷。實驗結果顯示，AA7003鋁合金陽極處理後的條紋缺陷，可能係因鋁基地之晶粒晶面指向不同，導致腐蝕速率的差異而形成。除此之外鋁合金表面缺陷，雖然是產生在鋁合金基材上，而不是在氧化層表面上；但是表面缺陷的產生，還是會影響到陽極處理後AA7003陽極層的生長品質與產品外觀。
關鍵詞：AA7XXX鋁合金、陽極處理、表面缺陷、表面光澤度
Abstract
The purpose of the study is to observe and analyze the surface defects of several anodized 7XXX Aluminum Alloys by using a variety of equipment, including optical microscopy, micro Vickers hardness testing equipment, confocal laser microscopy, white light interferometer and transmission electron microscopy (TEM). The mechanical property and microstructural changes of the heat-treated and then anodized 7XXX Aluminum Alloys are also investigated in the present study. The experimental results revealed that surface hardness of the 7XXX aluminum alloys were significantly better than the 6063 aluminum alloy; however the surface glossiness property seemed relatively poor because of the severe striped defects. The anodized 7003 aluminum alloy will possess the best combination of surface hardness and glossiness property among several 7XXX series aluminum alloys in the present study. The surface glossiness of the 7003 aluminum alloy was similar to that of the 6063 aluminum alloy: however the surface hardness of the 7003 aluminum alloy was obviously higher than the 6063 aluminum alloy. The thickness of the anode layer of the AA7003 aluminum alloy was measured to be about 10μm. It was found that during the process of anodic treatment, the surface of the aluminum matrix will also be affected by corrosion reaction in addition to the formation of an oxide anode layer. The obvious undulation will result in the severe striped defects on the surface of AA7003 aluminum alloy. Based on our experimental observations, the severe stripe-like defects may be caused by the different corrosion rates of grains with different orientation relationship of the aluminum matrix. It was noted that the stripe-like defects formed on the surface of the substrate will affect the quality and appearance of the anodic layer of the AA7003 aluminum alloy.
Keywords: 7XXX Aluminum Alloy, Anodic Treatment, Surface Defect, Surface Glossiness Property