在不同氣氛下Al-XMg(X=2,4wt%) 熱合氧化膜的成長機制

Thermally-Formed Oxide on Al-XMg(X=2,4wt%) Alloys in different atmosphere

吳俊逸(Yi-chun WU)

指導教授 ： 施登士

國立中央大學/工學院/機械工程學系/碩士(2007年)

摘要

本研究主要在探討鋁鎂合金熱成長氧化膜的分析，使用的材料有靶材鋁-2wt%鎂、鋁-4wt%鎂兩種。試片裁切成10 mm × 10 mm × 6 mm的大小，使用400號、800號、1200號、1500號跟2000號砂紙將表面乾磨，然後放在加熱爐中分別在空氣及氮氣下加熱到500℃，持溫1小時、6小時、25小時以生長氧化膜。
實驗結果發現，由於氧化鎂自由能低於氧化鋁，漸漸地而氧化膜的表面富含氧及鎂，表層變成以鎂的氧化物為主，所以鋁鎂合金在氣氛為空氣的加熱過程中其表面的氧化層主要以鎂的氧化物為主。鋁-2wt%鎂的氧化膜有氧化鋁、氧化鎂及尖晶石相的出現，鋁-4wt%鎂的氧化膜並沒有觀察到尖晶石相的產生，可知尖晶石相的產生取決於鋁鎂合金中的鎂含量。
氣氛為氮氣的加熱過程中其表面的氧化膜主要以鎂及鋁的氮化物為主在加熱過程中因為表層富含鎂，鎂會與氮氣反應形成Mg3N2的化合物，Mg3N2再與基材中的鋁反應形成AlN，生成AlN的量合金中的鎂含量有關，隨著加熱時間的增長氮氣中微量的氧會與Mg3N2及AlN反應成MgO與Al2O3。

關鍵字

熱合氧化膜 ； 尖晶石 ； AlN ； Mg3N2

並列摘要

The purpose of this study is analyzing the thermal-formed oxide on aluminum and magnesium alloys. Two materials, Al-2wt%Mg、Al-4wt%Mg were used in this study. The cube samples were prepared in 10 mm × 10 mm × 6 mm. They were then polished by ＃400, ＃800, ＃1200, ＃1500 and ＃2000 abrasive paper. These cube samples were moved to the muffle furnace in the air and nitrogen separately and then heated to 500℃ and hold on for 1 hr,6hrs,25hrs.
The experimental result find that the magnesium oxide and Gibbs-free energy are lower than the alumina, and the oxide film gradually is rich in oxygen and magnesium, the surface oxide layer which almost entirely magnesium oxide, so Al-Mg alloy oxide film is mainly the magnesium oxide for heating of air. The Al-2wt%Mg thermal oxide film appearance with alumina, MgO, MgAl2O4 spinel, and MgO appeared first on the surface of the sample and followed by formation MgAl2O4 spinel. The Al-2wt%Mg thermal oxide film doesn’t observe MgAl2O4 spinel, to transform MgAl2O4 spinel is depend on the content of Mg of Al-Mg alloy.
When Al-Mg alloy heat in the nitrogen, the surface is formed aluminum nitride and magnesium nitride, Mg react with nitrogen to form Mg3N2, then react and form AlN with aluminum. Formulation amount of the AlN is related to content of Mg of Al-Mg alloy. During long heat of time with nitrogen, the deleterious effect of oxygen impurities is due to its inhibition to the chemisorbtion of N2 molecules, then Mg3N2 and AlN transform to MgO and Al2O3 separately.

並列關鍵字

AlN and Mg3N2 ； spinel ； thermal oxide film

參考文獻

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