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11.
张羊换 《武汉理工大学学报(材料科学英文版)》2013,28(3):604-611
The nanocrystalline and amorphous Mg2Ni-type Mg2Ni1?x Co x (x = 0, 0.1, 0.2, 0.3, 0.4) alloys were synthesized by melt quenching technology. The structures of the as-cast and quenched alloys were characterized by XRD, SEM and HRTEM. The gaseous hydrogen storage kinetics of the alloys was measured using an automatically controlled Sieverts apparatus. The alloy electrodes were charged and discharged with a constant current density in order to investigate the electrochemical hydrogen storage kinetics of the alloys. The results demonstrate that the substitution of Co for Ni results in the formation of secondary phases MgCo2 and Mg instead of altering the major phase Mg2Ni. No amorphous phase is detected in the as-quenched Cofree alloy, however, a certain amount of amorphous phase is clearly found in the as-quenched alloys substituted by Co. Furthermore, both the rapid quenching and the Co substitution significantly improve the gaseous and electrochemical hydrogen storage kinetics of the alloys, for which the notable increase of the hydrogen diffusion coefficient (D) along with the limiting current density (I L ) and the obvious decline of the electrochemical impedance generated by both the Co substitution and the rapid quenching are basically responsible. 相似文献
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张羊换 《武汉理工大学学报(材料科学英文版)》2018,33(4):812-822
The La-Mg-Ni-Mn-based AB2-type La1-xCexMgNi3.5Mn0.5 (x = 0, 0.1, 0.2, 0.3, and 0.4) alloys were fabricated by melt spinning technology. The effects of Ce content on the structures and electrochemical hydrogen storage performances of the alloys were studied systematically. The XRD and SEM analyses proved that the experimental alloys consist of a major phase LaMgNi4 and a secondary phase LaNi5. The variation of Ce content causes an obvious change in the phase abundance of the alloys without changing the phase composition. Namely, with the increase of Ce content, the LaMgNi4 phase augments and the LaNi5 phase declines. The lattice constants and cell volumes of the alloys clearly shrink with increasing Ce content. Moreover, the Ce substitution for La results in the grains of the alloys clearly refined. The electrochemical tests showed that the substitution of Ce for La obviously improves the cycle stability of the as-spun alloys. The analyses on the capacity degradation mechanism demonstrate that the improvement can be attributed to the ameliorated anti-corrosion and anti-oxidation ability originating from substituting partial La with Ce. The as-spun alloys exhibit excellent activation capability, reaching the maximum discharge capacities just at the first cycling without any activation treatment. The substitution of Ce for La evidently improves the discharge potential characteristics of the as-spun alloys. The discharge capacity of the alloys first increases and then decreases with growing Ce content. Furthermore, a similar trend also exists in the electrochemical kinetics of the alloys, including the high rate discharge ability (HRD), hydrogen diffusion coefficient (D), limiting current density (IL) and charge transfer rate. 相似文献
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Nanocrystalline and amorphous LaMg_(12)-type LaMg_(11)Ni + x wt% Ni(x = 100, 200) alloys were synthesized by mechanical milling. Effects of Ni content and milling time on the gaseous and electrochemical hydrogen storage kinetics of as-milled alloys were investigated systematically. The electrochemical hydrogen storage properties of the as-milled alloys were tested by an automatic galvanostatic system. And the gaseous hydrogen storage properties were investigated by Sievert apparatus and a differential scanning calorimeter(DSC) connected with a H_2 detector. Hydrogen desorption activation energy of alloy hydrides was estimated by using Arrhenius and Kissinger methods. It is found that the increase of Ni content significantly improves the gaseous and electrochemical hydrogen storage kinetic performances of as-milled alloys. Furthermore, as ball milling time changes, the maximum of both high rate discharge ability(HRD) and the gaseous hydriding rate of as-milled alloys can be obtained. But the hydrogen desorption kinetics of alloys always increases with the extending of milling time. Moreover, the improved gaseous hydrogen storage kinetics of alloys are ascribed to a decrease in the hydrogen desorption activation energy caused by increasing Ni content and milling time. 相似文献
18.
为了改善Mg2Ni型合金气态及电化学贮氢动力学性能,用La部分替代合金中的Mg,用快淬技术制备了Mg2-xLaxNi(x=0,0.2,0.4,0.6)合金,用XRD,SEM,HRTEM分析了铸态及快淬态合金的微观结构;用自动控制的Sieverts设备测试了合金的气态贮氢动力学性能,用程控电池测试仪测试了合金的电化学贮氢动力学.结果发现,快淬无La合金具有典型的纳米晶结构,而快淬含La合金显示了以非晶相为主的结构,表明La替代Mg提高Mg2Ni型合金的非晶形成能力.La替代Mg明显地改变Mg2Ni型合金的相组成.当La替代量x=0.4时,合金的主相改变为(La,Mg) Ni3+ LaMg3.合金的气态及电化学吸放氢动力学对La含量及快淬工艺敏感,La替代使合金的吸氢动力学降低,但适量的La替代可以明显改善合金的放氢动力学及高倍率放电能力.适当的快淬处理可以提高合金的气态及电化学贮氢动力学,但获得最佳贮氢动力学的快淬工艺与合金的成分密切相关. 相似文献
19.
采用水热法合成La3+、Eu3+共掺杂纳米Ce1-x(La0.5Eu0.5)x O2-δ固溶体。利用X射线衍射技术(XRD)表征样品的相结构,并对固溶体的晶胞参数进行拟合。通过拉曼光谱及紫外可见漫反射光谱表征其电子跃迁性能及掺杂效应。XRD结果表明,双离子掺杂固溶限不小于x=0.30,样品晶粒尺寸小于20 nm,晶胞参数随着掺杂量的升高而逐渐增大。Raman光谱F2g振动峰的逐渐宽化及向低波数方向移动。紫外漫反射光谱表明,随着掺杂量的增大,固溶体能隙先蓝移后红移。 相似文献
20.
铜厂沟矿区多为破碎、中厚、急倾斜矽卡岩型铜钼矿体,原设计采用上向水平分层充填采矿法,在采矿实验中存在作业安全性差、劳动生产效率低、损失贫化大、采矿成本高等缺陷,严重制约了试生产组织。矿山急迫需要一种安全、高效、成本能够控制的采矿方法满足试生产矿石持续供应。通过充分研究,提出了低贫损分段崩落与浅孔留矿耦合采矿方法的设想,进一步降低了安全风险、简化工艺、控制损失贫化等。通过采矿方法的优化设计,解决了企业生产存在的实际问题,提高了采矿效率,对其它同类矿山具有一定的参考借鉴意义。 相似文献