Magnesium hydride 와 Mg-25Al 합금 Hydride 의 성장 및 분해 = The Formation and Decomposition of Magnesium Hydride and mg-25Al Alloy Hydride

국문 초록 (Abstract)

마그네슘과 Mg-25Al 合金의 粉末을 346℃∼400℃의 溫度범위에서 高壓水素와 직접 反應시켜 magnesium hydride를 合成하였으며, 反應生成物은 X-ray diffractometer를 使用하여 확인하였다. Magnesium과 Mg-25Al 合金의 두 경우 모두 生成된 hydride 相은 MgH₂의 형태로만 存在하였으며, 收率(反應한 magnesium의 무게 百分率)은 試料의 平均粒子가 적을수록 增加했고, 또 magnesium 에서 보다 Mg-25Al 合金에서 훨씬 높았다.
또 magnesium hydrided와 Mg-25Al 合金의 hydride 에 對해서 各各 流動 argon 雰圍氣, 287℃∼397℃의 溫度範圍에서 TGA方法을 使用하여 分解速度를 測定하였다. 두 경우 모두 初期段階의 反應速度는 界面에서의 化學反應에 의해서 支配되며, 이때의 反應速度式은 分解率X와 反應時間에 對해서, 1-(1-X)^(t-2)=k₁·t로 表示 되었다.
한편 分解反應의 活性化 energy는 magnesium hydrided와 Mg-25Al 合金의 hydride에 對해서 각각 19.5㎉/mole, 15.9㎉/mole 이었으며, Mg-Al 合金에 있어서 이러한 活性化 energy는 aluminum의 量이 增加할수록 減少하였다.

다국어 초록 (Multilingual Abstract)

The formation of magnesium hydride by the reaction of high pressure hydrogen (23 to-27 atm) with magnesium and Mg-25Al alloy powdered was studied in the temperature range of 346℃ to 400℃. And reaction products were identified by using a X-ray diffractometer.
For both magnesium and Mg-25Al alloy, hydride phase formed was found to exist in the form of MgH₂ only. Yields (weight percent of magnesium reacted) were increased with the decrease of average particle size of the sample, and were much higher for Mg-25Al Alloy than for magnesium.
Decompositions of magnesium hydride and Mg-25Al alloy hydride were also carride out under the dynamic argon atmosphere using a thermogravimetric technique, in the temperature range of 287℃ to 397℃. In both cases, the reaction rates of the initial stage were controlled by the chemical reaction at the interface. The rate equation for the initial stage was expressed, in terms of the fraction decomposed X and reaction time t, as 1-(1-X)=k·t.
The apparent activation energies for the decomposition reactions of magnesium hydride and Mg-25Al alloy hydride were 19.5 Kcal/mole and 15.9 Kcal/mole, respectively. And the activation energies for the dehydriding reactions in Mg-Al alloys were considered to decrease with aluminum content.