Nanocrystalline/amorphous LaMg(12)-type alloyNi composites with a nominal composition of LaMg(11)Ni+x wt% Ni(x=100,200) were synthesized by mechanical milling.Effects of Ni content and milling time on the gaseous hydr...Nanocrystalline/amorphous LaMg(12)-type alloyNi composites with a nominal composition of LaMg(11)Ni+x wt% Ni(x=100,200) were synthesized by mechanical milling.Effects of Ni content and milling time on the gaseous hydrogen storage thermodynamics and dynamics of alloys were systematically investigated.The hydrogen desorption properties were studied by Sievert apparatus and a differential scanning calorimeter(DSC).Thermodynamic parameters(△H and ΔS) for the hydrogen absorption and desorption of alloys were calculated by Van't Hoff equation.Hydrogen desorption activation energy of alloy hydride was estimated by Arrhenius and Kissinger methods.The increase in Ni content has a slight effect on the thermodynamic properties of alloys,but it significantly enhances the hydrogen absorption and desorption kinetics performance of alloys.Moreover,variation of milling time clearly affects the hydrogen storage properties of alloys.Hydrogen absorption capacity(C(100)~a) and hydrogen absorption saturation ratio(R(10)~a)(a ratio of the hydrogen absorption capacity at 10 min to the saturated hydrogen absorption capacity) have maximum values with milling time varying.But hydrogen desorption ratio(R(20)~d)(a ratio of the hydrogen desorption capacity at 20 min to the saturated hydrogen absorption capacity) always increases with milling time prolonging.Particularly,prolonging milling time from 5 to 60 h makes R(20)~d increase from 10.89% to 16.36% for the x=100 alloy and from 13.93% to 21.68% for the x=200 alloy,respectively.展开更多
To improve the hydrogen storage performance of CeMg12-type alloys, partially substituting Mg with Ni in the alloy was conducted. The way to synthesize the target alloy powders was the mechanical milling method, by whi...To improve the hydrogen storage performance of CeMg12-type alloys, partially substituting Mg with Ni in the alloy was conducted. The way to synthesize the target alloy powders was the mechanical milling method, by which the CeMg11-Ni ＋ x wt% Ni （x = 100, 200） alloy powders with nanocrystalline and amorphous structure were obtained. The influence of the milling time and Ni content on the hydrogen storage properties of the alloys was discussed. The X-ray diffractometer and high-resolution transmission electron microscope were used to investigate the microstructures of the ball-milled alloys. The hydrogenation/dehydrogenation dynamics were studied using a Sievert instrument and a differential scanning calorimeter which was linked with a H2 detector. The hydrogen desorption activation energies of the alloy hydrides were evaluated by Arrhenius and Kissinger equations. From the results point of views, there is a little decline in the thermo- dynamic parameters （enthalpy and entropy changes） with the increase in Ni content. However, the alloys desorption and absorption dynamics are improved distinctly. What is more, the variation of milling time results in a dramatic influence on the hydrogen storage performances of alloys. Various maximum values of the hydrogen capacities correspond to different milling time, which are 5.805 and 6.016 wt% for the CeMgllNi ＋ x wt% Ni （x = 100, 200） alloys, respectively. The kinetics tests suggest that the hydrogen absorption rates increase firstly and then decrease with prolonging the milling time. The improvement of the gaseous hydrogen storage kinetics results from the decrease in the activation energy caused by the increase in Ni content and milling time.展开更多
La0.8Pr0.2MgNi3.6Co0.4 alloys were prepared by induction melting,annealing and melt spinning techniques.The influences of annealing treatment and melt spinning on phase structure and hydrogen storage properties were s...La0.8Pr0.2MgNi3.6Co0.4 alloys were prepared by induction melting,annealing and melt spinning techniques.The influences of annealing treatment and melt spinning on phase structure and hydrogen storage properties were systematically investigated.The results of X-ray diffraction determine that the as-cast and as-spun La0.8Pr0.2MgNi3.6Co0.4 alloys consist of LaMgNi4 and LaNi5 phases,while only LaMgNi4 phase is present in the as-annealed alloy.The scanning electron microscope images illustrate that the grain of the alloy is significantly refined by melt spin ning tech no logy.The gaseous hydrogen storage kinetic and thermodynamic properties were measured by using a Sievert's apparatus at different temperatures.The maximum hydrogen storage capacity of the as-cast,as?spun and as-annealed La0.8Pr0.2MgNi3.6Co0.4 alloy is 1.699,1.637 and 1.535 wt.% at 373 K and 3 MPa,respectively.The annealed alloy has flatter and wider pressure plateaus compared with the as-cast and as-spun alloys,which correspond to the hydrogen absorption and desorption process of LaMgNi4 and corresponding hydride.Furthermore,the enthalpy and entropy changes of LaMgNi4 during hydrogenation at different temperatures were calculated using Van't Hoff methods.展开更多
Nanocrystalline and amorphous LaMg12-type alloy-Ni composites with a nominal composition of LaMg11Ni＋x wt.% Ni（x=100,200）were synthesized via ball milling.The influences of ball milling duration and Ni adding amoun...Nanocrystalline and amorphous LaMg12-type alloy-Ni composites with a nominal composition of LaMg11Ni＋x wt.% Ni（x=100,200）were synthesized via ball milling.The influences of ball milling duration and Ni adding amount xon the gaseous and electrochemical hydrogen storage dynamics of the alloys were systematically studied.Gaseous hydrogen storage performances were studied by a differential scanning calorimeter and a Sievert apparatus.The dehydrogenation activation energy of the alloy hydrides was evaluated by Kissinger method.The electrochemical hydrogen storage dynamics of the alloys was investigated by an automatic galvanostatic system.The H atom diffusion and apparent activation enthalpy of the alloys were calculated.The results demonstrate that a variation in Ni content remarkably enhances the gaseous and electrochemical hydrogen storage dynamics performance of the alloys.The gaseous hydriding rate and high-rate discharge（HRD）ability of the alloys exhibit maximum values with varying milling duration.However,the dehydriding kinetics of the alloys is always accelerated by prolonging milling duration.Specifically,rising milling time from 5to 60 h makes the hydrogen desorption ratio（a ratio of the dehydrogenation amount in 20 min to the saturated hydrogenation amount）increase from 57%to 66%for x=100alloy and from 57%to 70%for x=200.Moreover,the improvement of gaseous hydrogen storage kinetics is attributed to the descending of dehydrogenation activation energy caused by the prolonging of milling duration and growing of Ni content.展开更多
基金financially supported by the National Natural Science Foundation of China(Nos.51371094 and 51471054)
文摘Nanocrystalline/amorphous LaMg(12)-type alloyNi composites with a nominal composition of LaMg(11)Ni+x wt% Ni(x=100,200) were synthesized by mechanical milling.Effects of Ni content and milling time on the gaseous hydrogen storage thermodynamics and dynamics of alloys were systematically investigated.The hydrogen desorption properties were studied by Sievert apparatus and a differential scanning calorimeter(DSC).Thermodynamic parameters(△H and ΔS) for the hydrogen absorption and desorption of alloys were calculated by Van't Hoff equation.Hydrogen desorption activation energy of alloy hydride was estimated by Arrhenius and Kissinger methods.The increase in Ni content has a slight effect on the thermodynamic properties of alloys,but it significantly enhances the hydrogen absorption and desorption kinetics performance of alloys.Moreover,variation of milling time clearly affects the hydrogen storage properties of alloys.Hydrogen absorption capacity(C(100)~a) and hydrogen absorption saturation ratio(R(10)~a)(a ratio of the hydrogen absorption capacity at 10 min to the saturated hydrogen absorption capacity) have maximum values with milling time varying.But hydrogen desorption ratio(R(20)~d)(a ratio of the hydrogen desorption capacity at 20 min to the saturated hydrogen absorption capacity) always increases with milling time prolonging.Particularly,prolonging milling time from 5 to 60 h makes R(20)~d increase from 10.89% to 16.36% for the x=100 alloy and from 13.93% to 21.68% for the x=200 alloy,respectively.
文摘To improve the hydrogen storage performance of CeMg12-type alloys, partially substituting Mg with Ni in the alloy was conducted. The way to synthesize the target alloy powders was the mechanical milling method, by which the CeMg11-Ni ＋ x wt% Ni （x = 100, 200） alloy powders with nanocrystalline and amorphous structure were obtained. The influence of the milling time and Ni content on the hydrogen storage properties of the alloys was discussed. The X-ray diffractometer and high-resolution transmission electron microscope were used to investigate the microstructures of the ball-milled alloys. The hydrogenation/dehydrogenation dynamics were studied using a Sievert instrument and a differential scanning calorimeter which was linked with a H2 detector. The hydrogen desorption activation energies of the alloy hydrides were evaluated by Arrhenius and Kissinger equations. From the results point of views, there is a little decline in the thermo- dynamic parameters （enthalpy and entropy changes） with the increase in Ni content. However, the alloys desorption and absorption dynamics are improved distinctly. What is more, the variation of milling time results in a dramatic influence on the hydrogen storage performances of alloys. Various maximum values of the hydrogen capacities correspond to different milling time, which are 5.805 and 6.016 wt% for the CeMgllNi ＋ x wt% Ni （x = 100, 200） alloys, respectively. The kinetics tests suggest that the hydrogen absorption rates increase firstly and then decrease with prolonging the milling time. The improvement of the gaseous hydrogen storage kinetics results from the decrease in the activation energy caused by the increase in Ni content and milling time.
基金This work was financially supported by the National Natural Science Foundation of China(51901105,51871125 and 51761032)Inner Mongolia Natural Science Foundation(2017BS0507 and 2019BS05005)Inner Mongolia University of Science and Technology Innovation Fund(2016QDL-B02).
文摘La0.8Pr0.2MgNi3.6Co0.4 alloys were prepared by induction melting,annealing and melt spinning techniques.The influences of annealing treatment and melt spinning on phase structure and hydrogen storage properties were systematically investigated.The results of X-ray diffraction determine that the as-cast and as-spun La0.8Pr0.2MgNi3.6Co0.4 alloys consist of LaMgNi4 and LaNi5 phases,while only LaMgNi4 phase is present in the as-annealed alloy.The scanning electron microscope images illustrate that the grain of the alloy is significantly refined by melt spin ning tech no logy.The gaseous hydrogen storage kinetic and thermodynamic properties were measured by using a Sievert's apparatus at different temperatures.The maximum hydrogen storage capacity of the as-cast,as?spun and as-annealed La0.8Pr0.2MgNi3.6Co0.4 alloy is 1.699,1.637 and 1.535 wt.% at 373 K and 3 MPa,respectively.The annealed alloy has flatter and wider pressure plateaus compared with the as-cast and as-spun alloys,which correspond to the hydrogen absorption and desorption process of LaMgNi4 and corresponding hydride.Furthermore,the enthalpy and entropy changes of LaMgNi4 during hydrogenation at different temperatures were calculated using Van't Hoff methods.
基金financially sponsored by National Natural Science Foundation of China (51371094, 51471054)Natural Science Foundation of Inner Mongolia of China (2015MS0558)School of Materials and Metallurgy,Inner Mongolia University of Science and Technology,Project of Young Teachers'Personnel Training Supported(214CY012)
文摘Nanocrystalline and amorphous LaMg12-type alloy-Ni composites with a nominal composition of LaMg11Ni＋x wt.% Ni（x=100,200）were synthesized via ball milling.The influences of ball milling duration and Ni adding amount xon the gaseous and electrochemical hydrogen storage dynamics of the alloys were systematically studied.Gaseous hydrogen storage performances were studied by a differential scanning calorimeter and a Sievert apparatus.The dehydrogenation activation energy of the alloy hydrides was evaluated by Kissinger method.The electrochemical hydrogen storage dynamics of the alloys was investigated by an automatic galvanostatic system.The H atom diffusion and apparent activation enthalpy of the alloys were calculated.The results demonstrate that a variation in Ni content remarkably enhances the gaseous and electrochemical hydrogen storage dynamics performance of the alloys.The gaseous hydriding rate and high-rate discharge（HRD）ability of the alloys exhibit maximum values with varying milling duration.However,the dehydriding kinetics of the alloys is always accelerated by prolonging milling duration.Specifically,rising milling time from 5to 60 h makes the hydrogen desorption ratio（a ratio of the dehydrogenation amount in 20 min to the saturated hydrogenation amount）increase from 57%to 66%for x=100alloy and from 57%to 70%for x=200.Moreover,the improvement of gaseous hydrogen storage kinetics is attributed to the descending of dehydrogenation activation energy caused by the prolonging of milling duration and growing of Ni content.
