快淬纳米晶/非晶Mg2-xLaxNi (x=0～0.6)合金的贮氢动力学

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.     

球磨AB_5型储氢合金对BH_4~-的催化性能与其电化学性能的相关性研究

采用电弧熔炼和高能球磨方法联合制备了一系列不同球磨时间下的AB_5型MmNi_(3.55)Co_(0.75)Mn_(0.4)Al_(0.3)储氢合金样品,并对该系列合金样品的结构、电化学性能以及作为DBFC(直接硼氢化物燃料电池)阳极催化剂的催化性能进行了研究。探讨了合金样品的电化学性能与合金样品作为DBFC阳极催化剂对BH~-_4的催化性能之间的关系。研究结果表明,球磨没有改变合金的相组成,但改变了合金的相结构。所有球磨态AB_5型合金均由单一的CaCu_5型LaNi_5相组成。随着球磨时间的延长,合金非晶化程度越来越严重。随着球磨时间的延长,AB_5型合金样品的最大放电容量、放电性能以及循环稳定性均逐渐变差,同时球磨AB_5型合金作为DBFC阳极催化剂的催化性能以及稳定性也在逐渐变差。可见,球磨AB_5型合金的电化学性能与其作为DBFC阳极催化剂的催化性能呈正相关关系。铸态AB_5型MmNi_(3.55)Co_(0.75)Mn_(0.4)Al_(0.3)储氢合金样品呈现了最佳的综合电化学性能和作为DBFC阳极催化剂的催化性能。     

退火热处理对快淬态La_(15-x)Sm_xFe_2Ni_(76)Mn_5B_2储氢合金组织结构及电化学性能的影响

采用中频感应熔炼-快淬方法制备La15-xSmxFe2Ni76Mn5B2(x=0,2,4,6)型储氢合金。结构分析表明:快淬态La15-xSmxFe2Ni76Mn5B2(x=0,2,4,6)合金为多相结构,主相为La Ni5相,另外还有La3Ni13B2相和(Fe,Ni)相。快淬合金经1173 K保温3小时,而后随炉冷却到室温,随着Sm替代La的量不同,合金的组成相有着不同的变化。电化学测试表明,退火热处理明显提高了合金电极的最大放电容量,改善了合金电极的自放电性能。退火合金电极的高倍率放电能力均低于快淬合金,表明储氢合金电极的电化学动力学性能有所下降。     

球磨时间对MmNi3.9Co0.45Mn0.4Al0.25-CoB复合储氢合金电化学性能的影响

采用机械合金化方法制备MmNi3.9Co0.45Mn0.4Al0.25-CoB复合储氢合金.通过X射线衍射(XRD)分析、扫描电子显微镜(SEM)分析、充放电及线性极化测试.研究了球磨时间对复合储氢合金相结构及电化学性能的影响.研究结果表明:随着球磨时间的增加,复合储氢合金的衍射峰逐渐宽化,杂散衍射峰消失,表现出非晶化趋势;复合储氢合金颗粒尺寸变小,并星球状均匀分布.电化学测试结果表明:当球磨时间达到45 min时,复合储氢合金具有较好的活化及高倍率放电性能,30次循环容量保持卒最高,达到90.66%,表现出良好的电化学动力学性能及催化活性.但当球磨时间过长时,合金颗粒出现相互粘连及团聚的情况,局部出现较大结块,导致复合合金电极的交换电流密度降低.     

快淬对La0.67Mg0.33(NiCo)3贮氢合金电化学性能的影响

测试了AB3型贮氢合金La0.67Mg0.33(NiCo)3铸态与快淬态的电化学性能,用XRD和SEM测试了合金的微观结构,研究了快淬对AB3型贮氢合金电化学性能的影响.结果表明,快淬使合金的放电容量降低,对合金的活化性能没有明显影响;快淬降低了合金的容量衰减率,提高了合金的循环寿命,其主要原因是快淬使合金的晶粒显著细化.铸态和快淬态合金均具有多相结构,包括斜六面体的(La,Mg)Ni3相,六方的LaNi5相及少量的LaNi2相.快淬使合金中的LaNi2相含量增加,这是快淬使合金放电容量下降的一个主要原因.     

抽油泵柱塞杆耐磨耐腐涂层用镍基合金粉末的研究

选用高铁无钴及少量钼铜合金化，采用非真空中频感应炉熔炼、氮气雾化、水中淬冷的制粉工艺。研究出的合金粉末具有良好的喷焊性能、机械工艺性能和耐磨耐腐蚀性能     

抽油泵柱塞杆耐磨腐涂层用镍基合金粉末的研究

选用高铁无钴及少量钼铜合金化，采用非真空中频感诮炉熔炼，氮气雾化，水中淬冷的制粉工艺。研究出的合金粉末具有良好的喷焊性能，机械工艺性能和耐磨耐腐蚀性能。     

退火及快淬对La_(0.60)Pr_(0.15)Mg_(0.25)Ni_(3.2)Co_(0.20)Si_(0.10)储氢性能影响研究

采用熔炼法制备La_(0.60)Pr_(0.15)Mg_(0.25)Ni_(3.2)Co_(0.20)Si_(0.10)铸态储氢合金,将铸态合金分别在950oC条件下退火处理3 h,以及以1 m/s的速度进行快淬处理。系统研究三种合金的结构及储氢性能。XRD结果表明,退火及快淬处理后合金的相结构未发生明显变化,主相均为La Ni5相。电化学性能测试证明,与铸态合金相比,退火及快淬态合金的最大放电容量及循环稳定性均得到提升。动力学测试结果说明退火及快淬处理的合金高倍率性能降低,表面电荷转移电阻增大,交换电流密度升高,其中退火合金的极限电流密度具有最大值。     

热处理工艺对La0.85Ce0.15(NiMnAl)5.30贮氢合金相结构及电化学性能影响

本文研究了无钴La_0.85Ce_0.15(NiMnAl)_5.30贮氢合金在不同热处理工艺下相结构及电化学性能变化规律。衍射分析表明退火参数优化后的合金仍为CaCu5单相,温度升高后结晶度增加但活化性能变差;PCT测试结果显示920℃退火时吸氢量达到0.8902;温度升高后吸氢量呈现降低趋势,放氢压力也明显增加;经过980℃热处理8h后晶体结构改善明显,其吸放氢前后膨胀体积变化最小,抗粉化能力强。无钴合金熔点降低、温度升高后利于体相中元素扩散;活化性能降低的同时合金最大放电容量也有所降低。980℃制备合金电化学性能最优,同时具备较好的贮氢性能。     

快淬对合金Mm(NiCoMnAl)5.1B0.1组织及电化学性能的影响

对铸态和快淬态贮氢合金Mm(NiCoMnAl)5.1B0.1的微观组织和电化学性能进行了研究。发现快淬态合金基本上消除了第二相，快淬合金组织中存在一定比例的非晶相，并且随着淬速增加非晶相的量增多；与铸态合金相比，快淬态合金的放电容量有所降低，但循环寿命显著提高，这主要是由于快淬导致晶粒细化和形成一定数量的非晶态组织。     

Effect of Rapid Quenching on Microstructures and Electrochemical Performances of La2Mg（Ni0.85Co0.15）9M0.1 （M = B, Cr） Hydrogen Storage Alloys

The La-Mg-Ni-system （PuNi3-type） La2Mg （Ni0.85 Co0.15 ）9M0.1 （ M = B, Cr） hydrogen storage etectrode alloys were prepared by casting and rapid quenching. The electrochemical performances and microstructures of the as-cast and quenched alloys were determined and measured. The effects of rapid quenching on the microstructures and electrochemical properties of the alloys were investigated in detail. The obtained results show that the alloys are composed of the （La, Mg） Ni3 phase （PuNi3-type structure） and the LaNi5 phase, as well as the small amount of the LaNi2 phase. A trace of the Ni2B phase exists in the as-cast alloy containing boron, and the Ni2B phase in the alloy nearly disappears after rapid quenching. The relative amount of each phase in the alloys depends on the quenching rate. The rapid quenching technique can greatly improve the electrochemical performance of the alloy, and the effect of rapid quenching on the activation performances of the alloys is minor. Rapid quenching enhances the cycle stability of the alloy, and the cycle life of the alloy increases with the increase of the quenching rate.     

Relations between Quenching Rate and Electrochemical Characteristics of Mm (NiCoMnA1) 5Bx (x=0～0.2) Electrode Alloys

Low-Co AB5-type Mm(NiCoMnA1)5Bx (x = 0, 0.1, 0.2 ) electrode alloys were prepared by casting and rapid quenching.The effects of the rapid quenching on the lattice constants, microstructures and electrochemical characteristics of the alloys were investigated in detail.The obtained results show that the rapid quenching made lattice constants and cell volume increased.In a range of the quenching rate, rapid quenching can increase the discharge capacities of the alloys.However, the discharge capacity of the as-quenched alloy is lower than that of the as-cast alloy when quenching rate is more than a critical value.The cycle lives of the alloys increase monotonously with the increase of the quenching rate.     

非晶纳米晶双相结构Sn-Co-C负极材料的制备及性能表征

采用真空气雾化与高能机械球磨法结合,制备SnCoC复合材料作为锂离子电池负极材料,操作简单,时间短,易于实现工业化.采用X射线衍射(XRD)和扫描电子显微镜(SEM)检测合金粉末及复合材料的相结构和表面形貌,结果发现碳的引入不会对合金相结构产生影响,它以无定形碳形式存在,随着球磨时间的增加,合金由晶态向非晶态转变,且颗粒变得均匀,部分颗粒尺寸甚至达到纳米级.将制得材料组装成模拟电池,测试其电化学特性,结果表明:球磨20h的Sn-Co合金比未球磨的合金负极的比容量高且循环更稳定,而将台金与石墨球磨后,所得复合材料的电化学性能进一步提高,首次库仑效率最高达90.6％,50次循环后容量保持率66.7％.分析可知:通过将锡钴合金弥散在无定形碳中,获得非晶纳米晶双相结构的SnCoC复合材料.非晶材料的各向同性,能够缓冲Li-Sn在合金化-去合金化过程中产生的结构和电场应力;纳米级尺寸的材料内部空隙多,有利于锂离子的扩散;碳材料除了稳定的结构外还可以提供一定的容量.这些有利因素结合起来,极大改善了材料的电化学性能.     

高能球磨制备非晶粉末的形成机理及形成能力的研究综述

综述了高能球磨制备非晶粉末的热力学条件和动力学条件以及非晶转变机制,介绍了工艺参数对非晶形成的影响以及合金粉末在高能球磨条件下的非晶形成能力预测理论。对利用高能球磨制备非晶粉末时的合金成分设计有一定的意义。     

Highly ameliorated gaseous and electrochemical hydrogen storage dynamics of nanocrystalline and amorphous LaMg12-type alloys prepared by mechanical milling

Nanocrystalline and amorphous LaMg12-type alloy-Ni composites with a nominal composition of LaMg11 Ni+x wt.% Ni (x=100, 200) were synthesized via ball milling.The influences of ball mill-ing duration and Ni adding amount x on 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 dynam-ics of the alloys was investigated by an automatic galvanostatic system.The H atom diffusion and ap-parent 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 perform-ance of the alloys.The gaseous hydriding rate and high-rate discharge (HRD) ability of the alloys ex-hibit 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 5 to 60 h makes the hydrogen desorption ratio (a ratio of the dehydrogenation amount in 20 min to the saturat-ed hydrogenation amount) increase from 57% to 66% for x=100 alloy 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.     

La15Fe77-xNixMn5B3（x=55,60,65,70,75）储氢合金的结构与电化学性能研究

用熔炼-快淬工艺制备La15Fe77-xNixMn5B3(x=55,60,65,70,75)储氢电极合金。采用XRD、SEM、EDS及电化学方法研究合金的组织结构、放氢平台特性和电化学性能。研究结果表明,La15Fe77-xNixMn5B3(x=55,60,65,70,75)合金均为多相结构,主相是LaNi5相,另外还有(Fe,Ni)相和La3Ni13B2相。随Ni含量增加,合金电极的最大放电容量逐渐增加,活化次数明显减少,放氢平台特性变好,高倍率放电性能明显改善。     

铜模吸铸与高能球磨制备Zr46Cu46Al8非晶合金的组织结构及晶化动力学研究

采用铜模吸铸法制备出直径3 mm的Zr₄₆Cu₄₆Al₈块体非晶合金, 利用高能球磨法获得了不同粒径的合金粉体, 通过X射线衍射仪、示差扫描量热仪、扫描电镜等测试手段及热力学计算方法, 研究了制备方法对非晶合金组织结构及晶化动力学的影响。结果表明, 块体合金和粉体合金均可获得完全非晶结构; 块体非晶合金玻璃转变和晶化过程具有明显的动力学效应; 单因素变量法制备非晶粉体的最佳参数为: 转速300 r·min-1, 球料比30:1, 球磨时间15 h; 相同条件下, 除过冷液相区外, 块体非晶合金热力学参数普遍高于非晶粉体, 且晶化放热更剧烈; 随着加热速率增大, 二者热力学参数均向高温区移动, 过冷液相区的宽度也逐渐增加; 块体非晶合金和非晶粉体的特征温度表观激活能数值相近, 块体非晶态合金的表观激活能较非晶粉体高, 热稳定性更优。     

Influence of rapid quenching on cyclic stability of La-Mg-Ni system （AB3-type） electrode alloys

Aiming at the improvement of the cyclic stability of La-Mg-Ni system （PuNi3-type） hydrogen storage alloy, Ni in the alloy was partly substituted by Fe. The electrode alloys of La0.7Mg0.3Co0.45Ni255-xFex （x=0, 0.1, 0.2, 0.3, 0.4） were prepared by casting and rapid quenching. The influence of the quenching on cyclic stability as well as structure of the alloys was investigated in detail. The results of electrochemical measurement indicated that rapid quenching significantly improved cyclic stability. When the quenching rate rose from 0 （As-cast was defined as a quenching rate of 0 m/s） to 30 m/s, the cyclic life of Fe-free alloy （x=-0） increased from 81 to 105 cycles, and for alloy containing Fe（x=0.4）, it grew from 106 to 166 cycles at a current density of 600 mA/g. The results obtained by XRD, TEM and SEM revealed that the as-cast and quenched alloys had multiphase structures, including two major phases （La, Mg）Ni3 and LaNi5 as well as an imptLrity phase LaNi2. Rapid quenching helped the formation of an amorphous-like structure in Fe containing alloys.     

Effects of Fe-substitution for cobalt on electrochemical properties of La-Mg-Ni-based alloys

In order to improve electrochemical properties,especially cycling stability,Co was partially substituted by Fe in A2B7-type La-Mg-Ni-based alloys.The La0.74Mg0.26Ni2.55Co0.65-xFex(x=0,0.10,0.20,0.30) alloys were prepared by inductive melting,and their phase structure and electrochemical properties were studied.The XRD and SEM results showed that the alloys consisted mainly of(La,Mg)2Ni7 phase,(La,Mg)5Ni19 phase and LaNi5 phase,except for absence of LaNi5 phase in the non-substituted alloy.The(La,Mg)5Ni19 ph...     

Study on structure and electrochemical properties of the （LaGdMg）Ni3.35-xCoxAl0.15（x=0-2.0） hydrogen storage alloys

Hydrogen storage alloys(LaGdMg)Ni3.35-xCoxAl0.15(x=0,0.1,0.3,0.5,1.0,1.5,2.0) were prepared by induction melting followed by annealing treatment in argon atmosphere.The effects of partly replacing Ni by Co element in(LaGdMg)Ni3.35Al0.15 on the phase structure and electrochemical properties of(LaGdMg)Ni3.35-xCoxAl0.15 alloys were investigated.Structure analysis showed that the alloys consisted of Ce2Ni7-type(Gd2Co7-type),CaCu5-type,Pr5Co19-type,PuNi3-type phase structure.The addition of Co element obviously reduced the contents of CaCu5-type phase and increased the contents of Ce2Ni7-type phase.However,Pr5Co19-type and CaCu5-type phase obviously increased with the high content of Co.Rietveld analysis showed that the c-axis lattice parameters and cell volumes of the component phases increased with increasing Co content.The electrochemical measurements showed that as the Co content increased,the maximum discharge capacity and the cyclic stability of the annealed alloys both first increased then decreased.The(LaGdMg)Ni3.05Co0.3Al0.15 alloy electrode exhibited the maximum discharge capacity(392.92 mAh/g),and the(LaGdMg)Ni1.85Co1.0Al0.15 alloy electrode showed the best cyclic stability(S100=96.1%).