Hydrogen sorption properties of nanocrystalline Mg2FeH6-based complex and catalytic effect of TiO2

The diversities of hydrogen sorption properties of Mg₂FeH₆-based complexes with and without TiO₂ were investigated. Mg₂FeH₆-based complexes with and without TiO₂ were synthesized respectively by reactive mechanical alloying, and hydrogen sorption properties of the complexes were examined by Sieverts-type apparatus. The results show that the sample without TiO₂ releases 4.43 % (mass fraction) hydrogen in 1.5 ks at 653 K under 0.1 MPa H₂ pressure and absorbs 90% of the total 4.43 % (mass fraction) hydrogen absorbed in 85 s at 623 K under 4.0 MPa H₂ pressure. But for the sample with TiO₂ addition under the same condition, it only needs 400 s to release all of the stored hydrogen and 60 s to absorb 90% of the total hydrogen absorbed. The activation energies for desorption process of the samples with and without TiO₂ are determined to be 71.2 and 80.3 kJ/(mol·K), respectively. The improvement in hydrogen sorption rate and and reduction in activation energy can be attributed to the addition of TiO₂.     

Synthesis of nanostructured Mg2FeH6 hydride and hydrogen sorption properties of complex

Reactive mechanical alloying(RMA)was carried out in a planetary ball mill for the synthesis of ternary hydride Mg2FeH6 for hydrogen storage.The formation mechanism of Mg2FeH6 in RMA process and the sorption properties of the products were investigated.The results show that Mg2FeH6 has a yield ratio around 80%,and a grain size below 10 nm in the powder synthesized by milling 3Mg+Fe mixture for 150 h under the hydrogen pressure of 1 MPa.The synthesized powder possesses a high hydrogen capacity and good sorption kinetics,and absorbs 4.42%(mass fraction)of hydrogen within 200 s at 623 K under the hydrogen pressure of 4.0 MPa.In releasing hydrogen at 653 K under 0.1 MPa,it desorbs 4.43%(mass fraction)of hydrogen within 2 000 s.The addition of Ti increases the hydrogen desorption rate of the complex in the initial 120 s of the desorption process.     

LaNi_5对机械合金化合成Mg_2FeH_6基复合物放氢性能的影响

放氢性能是镁基储氢材料应用的关键。该研究采用机械合金化和熔炼的方法分别合成Mg2FeH6基复合物和LaNi5,然后将70%(质量分数)的Mg2FeH6基复合物和30%的LaNi5进行球磨复合,得到Mg2FeH6基复合物,研究LaNi5对Mg2FeH6基复合物放氢性能的影响。研究结果显示该复合物具有良好的放氢动力学性能,在553 K放氢量可达到1.46%(质量分数);在653 K下120 s内可释放总放氢量的80%,最终放氢量为3.6%。LaNi5的添加可降低Mg2FeH6基复合物的放氢温度,提高放氢速率。     

La2O3-Y2O3-ZrO2纳米陶瓷粉末的制备及高温相稳定性

用化学共沉淀法制备4.5%Y2O3-ZrO2(YSZ)和0.6%La2O3-YSZ、0.8%La2O3-YSZ、1.2%La2O3-YSZ(0.6La、0.8La、1.2La)(摩尔分数)纳米复合陶瓷粉末,研究了四组粉末的高温相稳定性.结果表明:采用正向滴淀方法制备的0.6La粉末(粒径～50 nm)团聚严重,而用反向...     

钕铁硼永磁材料腐蚀机理及表面防护技术现状

综合论述钕铁硼永磁材料的物相组成、腐蚀机理以及表面防护工作,阐述了钕铁硼永磁材料高温氧化、湿热吸氢和电化学腐蚀的腐蚀特性以及电镀、化学镀该领域应用现状以及这些技术的基本原理、技术特点、研究现状及发展趋势。