铸态及快淬态无钴AB5型贮氢合金的循环稳定性

对AB5型LaxMm1-x(NiMnSiAlFe)49(x=0,0.45,0.75,1.00,摩尔分数)贮氢合金进行了快淬处理,研究了La含量及快淬工艺对合金微观结构及电化学循环稳定性的影响.结果表明:La含量的增加对铸态合金的循环稳定性没有明显影响,但使快淬态合金的循环稳定性下降,且快淬处理能显著提高合金的循环稳定性.当La替代量从0增加到1.00时,经300次充放循环后,铸态合金的容量保持率(Rh)从59.2%增加到59.8%;16 m/s淬速快淬态合金的容量保持率从83.9%下降到65.0%.对于x=0.45的合金,当淬速从0(铸态被定义为淬速等于0)增加到28 m/s时,容量保持率从59.8%增加到75.8%.     

快淬工艺对无钴AB5型贮氢合金循环稳定性的影响

研究了快淬工艺对无钴AB5型LaxMm1-x(NiMnSiAlFe)4.9(x=0,0.45,0.75,1.0)合金微观结构及电化学循环稳定性的影响.结果表明快淬处理显著改善合金的成分均匀性,使晶粒细化,并显著提高合金的循环稳定性.当淬速从0m/s增加到28 m/s时,经300次充放循环后,x=0.45合金的容量衰减率D从0.28 mAh/g·c-1(c代表一次循环)下降到0.13mAh/g·c-1;x=1.0合金的容量衰减率D从0.3mAh/g·c-1下降到0.14mAh/g·c-1.     

Fe替代Co对AB5型贮氢合金循环稳定性的影响

用铸造及快淬的方法制备了稀土基AB5型Mm（NiMnSiAl）4．3Co0.6-xFex（x=0，0．1，0．2，0．3，0．4，0．5，0．6）贮氢合金，用XRD。TEM及SEM观测了铸态及快淬态的微观结构，测试了合金在铸态及快淬态下的电化学循环稳定性。研究了Fe替代Co对铸态及快淬态贮氢合金微观结构及循环稳定性的影响。研究结果表明，Fe替代Co对铸态及快淬态合金的相结构没有明显影响，但对合金的循环稳定性产生显著影响。Fe替代Co能不同程度地改善铸态及快淬态合金的循环稳定性，但对快淬态合金循环寿命的改善更加显著，导致这一结果的主要原因是Fe替代Co使快淬态合金的微观组织显著细化。     

硼对低钴AB5型贮氢合金循环寿命的影响

为了提高低钴AB5型贮氢合金的电化学循环稳定性，在低钴AB5型贮氢合金中加入微量的硼，用真空快淬工艺制备了稀土系低钴AB5型MmNi3.8Co0.4Mn0.6Al0.2Bx(x=0，0．1，0．2，0．3，0．4)贮氢合金，分析测试了铸态及快淬态合金的电化学性能及微观结构，研究了硼对铸态及快淬态合金微观结构及循环寿命的影响。结果表明，硼能大幅度提高铸态及快淬态低钴AB5型贮氢合金的电化学循环稳定性，但其作用机理是完全不同的。     

钎焊及钛基钎焊料的发展及应用

本文介绍了钎焊及钛基钎焊料的发展及其应用。对钎焊的特点及钎焊料应具备的性能进行了较为全面的论述。对不同状态钎焊料的性能特点进行了全面的比较，特别是对在航天、航空领域广泛应用的非晶钛基钎焊料进行了重点介绍。     

La0.7Mg0.3Ni2.55-xCo0.45Alx(x=0～0.4)贮氢合金的循环稳定性

为了提高La-Mg-Ni系贮氢合金的循环稳定性,以Al部分替代Ni,采铸造及快淬工艺制备了La0.7Mg0.3Ni2.55-xCo0.45Alx(x=0,0.1,0.2,0.3,0.4)电极合金,研究了Al替代量及快淬工艺对合金微观结构及电化学循环稳定性的影响。X射线衍射分析结果表明:铸态及快淬态合金具有多相结构,包括(La,Mg)Ni3相、LaNi5相和一定量的LaNi2相;Al替代使铸态合金中LaNi2相的量显著增加,但对快淬态合金中LaNi2相的相丰度影响不显著。电化学测试结果表明:随Al替代量的增加,合金的循环寿命大幅度提高;快淬处理可以提高合金的循环寿命,但随Al替代量的增加,淬速对循环寿命的影响减小。     

铸态Mm(NiCoMnAl)5.1Bx贮氢合金电化学性能研究

本文研究了B含量对铸态非化学计量比贮氢使合金Mm(NiCoMnAl)5.1Bx的相结构及其电化学性能的影响。结果表明，加B合金中除了CaCu5相以外还含有一定量的第二相MmCo4B，且随着B元素含量的增加而增加；B的加入有利于提高合金的活化性能和高倍率放电性能，合金的循环寿命亦有所提高，但不利于合金的放电容量和放电电压性能。     

Gaseous and electrochemical hydrogen storage kinetics of as-quenched nanocrystalline and amorphous Mg2Ni-type alloys

The nanocrystalline and amorphous Mg₂Ni-type Mg₂Ni_1?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.     

快淬贮氢合金的活化性能与寿命

主要讨论了快淬钛基合金具有良好活化性能及较差循环寿命的机理。研究结果表明:快淬钛基合金电极浸泡在碱液中,合金元素V、Zr、Ti、Mn、Ni以不同速度溶解,其中Ni的溶解速度最慢,使合金电极表面富Ni。富Ni电极表面具有良好的动力学性能,快淬钛基贮氢合金的放电容量急剧衰退与损失大量可吸氢的V、Zr元素密切相关。     

Structures and Electrochemical Performances of As-spun RE-Mg-Ni-Mn-based Alloys Applied to Ni-MH Battery

The La-Mg-Ni-Mn-based AB₂-type La_1-xCe_xMgNi_3.5Mn_0.5 (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 (I_L) and charge transfer rate.