| 摘要: | 本論文主要是觀察在不同氣氛下鋁合金熱合氧化膜的成長機制及氫對於鋁合金的陽極行為之觀察。研究方向分成兩個部份:第一部份為鋁矽和鋁鎂合金在不同氣氛下的熱合氧化膜的成長機制;第二部份為氫對於鋁合金的陽極行為之觀察。首先， 第一部份是在不同氣氛下 鋁合金的熱合氧化膜， 使用TGA、XRD 以及EPMA 分析Al–XSi, Al-YMg 合金在不同氣氛下加熱時的重量變化。Al-1.2%Si 合金試片在空氣和氮氣氣氛中加熱時， 所生成的氧化膜是鬆散的， 並且由Gibbsite、Diaspore、γ -氧化鋁、金屬鋁及矽所組成。Al- 2 和3.5wt%Mg 合金在空氣與氮氣中加熱， Al-2 wt% Mg 之熱合氧化膜係由γ- alumina、MgO、Spinel、Gibbsite 所組成。至於在Al-3.5wt%Mg 試片的熱合氧化膜中則出現大量的MgO， 而不見Spinel。在氮氣中加熱至773K（ < 1.94 h），Al-3.5wt%Mg 試片產生Gibbs i t e 與γ-alumina 的量比Al-2wt%Mg 試片多，若延長時間至6h 試片中的氮化鋁(AlN)（ 或氧化鎂(MgO)） 含量較先前的試片增加許多。 本研究的第二部分是鋁合金基地中氫含量對陽極皮膜的影響， 通入定電流，量測電壓(V)對時間( t )的變化，將電壓-時間曲線進行微分，可以判斷各階段的能量消耗。研究結果顯示， 氫含有會影響第三階段的陽極能量消耗。當在第二階段後期電壓超過25V 以及第二加第三的能量消耗達到7 . 4 J / cm2 時， 陽極孔洞容易發生分支或合併， 並且在第三階段的微分曲線會有跳動現象。第二階段末期高電壓和高氫的試片， 在硫酸溶液所生長的陽極氧化膜會有Boehmi t e。本研究以一個獨特的工具， 了解純鋁試片的陽極生長行為， 陽極孔洞會有分支或合併現象以及陽極皮膜中會有部分結晶， 可以在第三階段的微分曲線跳中發現。 This thesis aimed at investigating thermally formed oxide films on aluminum alloys heated in different gases and hydrogen content on development of anodic aluminum oxide growth behavior. The study can be divided into two main parts. First, the thermally formed oxide films on Al-XSi and Al-YMg alloy heated in different gases. Second, the effects of hydrogen content on development of anodic aluminum oxide film on pure aluminum were observed. Part I: Thermally formed oxide films on Al–XSi, Al-YMg alloys heated in different gases. The XRD, EPMA and TGA analysis testing was used to polished samples of Al–XSi and Al-YMg alloys. The thermally formed surface oxide films on the Al–1.2wt% Si alloy samples heated in air and in nitrogen gas possessed loose structures, which comprised mainly γ-alumina, Diaspore, and Gibbsite, along with metallic silicon and/or aluminum. Weight changes in Al-2 and 3.5wt% Mg samples were first heated in a dry air atmosphere. The oxide film formed on the Al-2wt% Mg sample comprised γ-alumina, MgO, Spinel and Gibbsite. The film formed on the Al-3.5wt%Mg sample contained large quantities of MgO, but no Spinel. The samples were then heated in a nitrogen gas atmosphere for <1.9 h. The Al-3.5wt% Mg sample contained greater amounts of Gibbsite and γ-alumina than did the Al-2 wt% Mg sample. The latter yielded a greater amount of AlN (and/or MgO). After an extended holding time (~6 h), the Al-3.5wt% Mg sample contained a greater amount of AlN (and/or MgO), and its weight increased remarkably. Part II: The effect of hydrogen content on development anodic aluminum oxide growth behavior. To ensure constant current densities, voltage-time (V-t) curves were recorded during the experiment. The differential ΔV/Δt curves were plotted in order to compute the energy consumed at different steps of anodization. Experimental observations showed that differences in hydrogen content affected the energy consumed in 3 steps in the process that we defined. When the voltage response at the end of step 2 exceeded 25 V, the energy consumed in steps 2 + 3 reached or exceeded 7.4 J/cm2, and the pore channels branched or merged, creating a spike in the ΔV/Δt curves in step 3. Combining the effects of the high voltage response at the end of step 2 and the high hydrogen content in the Al samples, the anodic aluminum oxide (AAO) film formed in the sulfuric acidic solution, produced crystallized boehmite. This study proposes a unique tool for understanding certain special anodic behaviors of pure Al from which the branching or merging of pore channels and the partial crystallization of the AAO film can be ascertained via irregularities in ΔV/Δt curves obtained in step 3. |
