The Research of Hydriding Characteristics for Mg-xTi-2xFe Series Hydrogen Storage Alloys by Reactive Mechanical Grinding

• Main Authors: LU, WEN-CHUN, 陸文俊
• Other Authors: LIN, MING-HONG
• Format: Others
• Language: zh-TW
• Published: 2017
• Online Access: http://ndltd.ncl.edu.tw/handle/gxkra2

博士 === 國立高雄應用科技大學 === 機械工程系 === 105 === Magnesium-based hydrogen storage alloys have excellent hydrogenation properties and high hydrogen storage characteristics. But the grinding of the surface on the magnesium and alloys easily form a dense oxide layer;It is necessary to undergo multiple activation for gaining higher efficiency of hydrogenation then release hydrogen at a higher temperature. The characteristics of the Ti-Fe system are the inexpensive materials and easily reversible hydrogenation under the room temperature and atmospheric pressure. However, it is sensitivity to oxidation and has poor resistance to the poisoning of impurity gas. In this study, Ti and Fe were added into the Mg powder with different proportions, Mg and Ti were added as the second and the third elements, the weight percentage was set to Mg-xTi-2xFe to investigate the crystal composition, structure, hydrogen absorption and desorption properties, in order to find the best hydrogen storage materials. From the table of PCT, We know that the sample with Mg-15% Ti-30% Fe is the most reasonable condition; the following advantages can be obtained: 1. Magnesium does not adhere to the mill wall during milling, which helps to achieve grinding of nano-amorphous hydrogen storage alloy powders. 2. Simply activated, the sample powder can be in the low-pressure state and 320 ℃ for hydrogen absorption and desorption. 3. Non-hydrogenated magnesium accounts for only about 24.9% of the total Mg, which is much better than 59.9% of the pure Mg. 4. Excessive Fe clusters on the surface of the substrate, which protects the A element from oxidation, and acts as a catalyst in the hydrogen absorption and desorption. 5. These elements and amorphous compounds have different thermal expansion coefficients, which leads to the expansion of the powder and the cracking of matrix in the heating. After heating, the A element and AB amorphous compounds increases the fresh surface, which is exposed to hydrogen atoms and undergo hydrogenation. The hydrogen molecules combine with the A element and the AB amorphous compound to form AH2 and HAB amorphous compounds.