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La/Ce对AB5型合金气态吸放氢动力学性能的影响

Effect of La/Ce on the gas-phase hydrogen absorption and desorption kinetics of AB5-type alloy

  • 摘要: 采用真空电弧炉熔炼法制备了La1-xCexNi5(x=0,0.25,0.5)稀土基储氢合金,并通过XRD和PCT分析研究了La/Ce含量对其微观结构和吸放氢动力学的影响。XRD结果表明:氢化前合金的主相为LaNi5相,使用Ce部分替换La未能改变相组成,但是合金的晶胞体积随Ce含量的增加而逐渐减小。合金的吸放氢动力学表明:随着Ce含量的增高,合金的等温平台压力逐渐升高,且吸氢动力学加快,当x=0.5时,合金达到吸氢曲线拐角的时间为52 s。此外,放氢活化能也随Ce含量的增加而降低,其中x=0.5合金放氢活化能为28.5 kJ/mol。

     

    Abstract: The La1-xCexNi5(x = 0,0.25,0.5) rare earth-based hydrogen storage alloys were prepared by vacuum arc furnace melting method. The effects of La/Ce content on the microstructure and hydrogen absorption and desorption kinetics were investigated through XRD and PCT. The XRD results showed that the main phase of the hydrogenated alloy was LaNi5. Partial substitution of La with Ce did not change the original phase composition,but the unit cell volume of the alloy gradually decreased. In addition,the isothermal platform pressure of the alloy gradually increased as the amount of Ce increases,and the hydrogen absorption kinetics accelerated. When x = 0.5,the time for the alloy to reach the inflection point of the hydrogen absorption curve was 52 s. Moreover,the desorption activation energy also decreased with the increase of Ce content. The desorption activation energy of the x = 0.5 alloy was 28.5 kJ/mol.

     

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