吸铸对钛钒铬基合金结构和贮氢性能的影响

研究了吸铸对钛钒铬基合金结构和贮氢性能的影响。结果表明：吸铸有利于钛钒铬基合金单一BCC结构固溶体相的形成，使合金相的点阵常数略有减小；吸铸使钛钒铬基合金的放氢压力平台的斜率因子Sf降低，平台压力略有降低，活化性能变差，还使合金吸氢量和放氢量均有提高；随着Cr含量的增加，合金放氢的平台压力逐渐升高，放氢量提高。     

吸、放氢循环对V及V0.9Cr0.1合金储氢性能的影响

通过添加少量LaNi5对V以及V0.9Cr0.1合金进行有控制的机械合金化处理,改善了材料的活化性能.吸、放氢循环测试表明,吸、放氢循环超过100次并脱氢后,V和V0.9Cr0.1合金仍然保持单一bcc结构.随着吸、放氢循环的进行,V的吸、放氢平台压力不断增加,相同压力下吸氢量减小,且吸氢动力学有所下降.这与吸、放氢过程中晶格应变的降低和晶胞体积的减小有关.SEM观察表明,随着吸、放氢循环次数的增加,材料表面和内部形成大量的深裂纹,这对提高放氢平台压力和改善放氢动力学有促进作用.吸、放氢循环过程中,V比V0.9Cr0.1合金放氢容量衰减更快的原因是:吸、放氢循环前、后V的晶格应变降低和晶胞体积下降程度均比V0.9Cr0.1合金的要大,导致吸、放氢循环后V的吸氢量下降更大.     

Zr0.9Ti0.1V2合金循环吸放氢稳定性

研究了Zr0.9Ti0.1V2合金的循环吸放氢性能。合金在吸氢P-C-T曲线的特征区域内具有良好的循环吸氢稳定性,在P-C-T曲线的吸氢平台区（H/A为0.5左右）、吸氢形成氢化物初始阶段（H/A为1~1.2）、吸氢形成氢化物中间阶段（H/A为1.4左右）吸放氢循环测试中,每组循环内合金的吸氢量差别非常小,循环吸氢稳定性很好。经过70次吸氢循环后,合金的吸氢量可以恢复到1.957 (H/A),合金的粉碎程度很低,表明合金具有良好的循环吸氢能力     

新型钒基储氢合金的机械合金化制备工艺研究

采用机械合金化制备了新型钒基储氢合金V_3TiNi_(0.56)Mn_(0.1)Y_(0.1),并对该合金进行OM、SEM、XRD分析以及吸放氢性能和循环稳定性测试。结果表明:该新型储氢合金由V基固溶体和少量TiNi组成,具有较佳的吸放氢性能和循环稳定性,室温吸氢量约在55 min达到饱和,最大吸氢量为1.497 wt%;具有明显的放氢平台,平台压力为0.5 MPa;充放电循环15次后放电容量仅下降了5.6%。     

（Ti0.1V0.9）100-xFex（x=0～6）储氢合金的微观结构及储氢特性

研究了（Ti0.1V0.9）100-xFex（x=0～6）合金的微观结构及其吸放氢特性。微结构分析表明，合金均由单一的体心立方（bcc）结构的钒基固溶体相组成；合金的点阵常数随着Fe含量的增加呈线性递减，晶胞体积也随之逐渐降低。储氢性能测试表明，所有合金的动力学性能均比较好，在10℃和4MPa初始氢压条件下，合金无需氢化孕育期就能吸氢。随着Fe含量从x=0增加至x=6，合金的活化性能得到改善；10℃最大吸氢量从509．5ml／g逐渐降至424．8ml／g；50℃有效放氢量先升后降，并在x=4时达到最高值255．6ml／g。在所研究的合金中，Ti9.6V86.4Fe4合金具有最佳综合性能，经2次吸放氢循环即可活化，10℃最大吸氢量为494．5ml／g，50℃有效放氢量达到255．6ml／g。     

Ti-V-Fe系储氢合金的相结构及吸放氢特性

系统研究了Ti100-x-yVxFey（x=54，49，44；y=5，7．5，10）储氢合金的相结构及其吸放氢性能。XRD及SEM分析表明，Ti41V54Fes合金由体心立方（BCC）结构的固溶体主相和少量的α-Ti第二相组成；而Ti43．5V49Fe7．5和Ti46V44Fe10合金均为单一的BCC固溶体相。储氢性能测试表明，3种合金的动力学性能均很好，在室温和4MPa初始氢压条件下，无需氢化孕育期就能快速吸氢：经4次～5次吸放氢循环即能活化，仅2min～3min就能吸氢饱和达到最大吸氢量363．7ml／g-372．4ml／g；在300℃和0．1MPa放氢终压条件下，合金的放氢量在220．3ml／g-238．5ml／g之间。在所研究的合金中，Ti46V44Fe10合金的综合性能最佳，经4次吸放氢循环即活化，室温最大吸氢量可达372．4ml／g，放氢量达到238．5ml／g。     

ZK60-Pd合金的高周吸放氢循环性能

对ZK60贮氢合金球磨时添加C和Pd元素,进行了500次吸放氢循环性能试验。结果表明,随循环次数的增加,合金吸放氢量降低,前50次明显,第50次时降为第1次的83.9%,后续高周循环吸放氢量基本相同,吸放氢速率变化不明显。高周吸氢动力学性能较好,表面没有阻碍吸氢的化合物生成,高周循环后合金颗粒发生明显粉化。     

钛钒铬基合金的贮氢性能研究

钛钒铬基贮氢合金贮氢量大，吸放氢条件温和，是国内外贮氢材料研究的热点之一。为此研究了钛钒铬基合金中V、Cr含量对贮氢性能的影响，结果表明：随着金属元素V含量的增加，合金的放氢平台压力略有降低和吸放氢量略有增大。而随着金属元素Cr含量的增加，合金的放氢平台压力升高，放氢量则明显提高。随着放氢温度提高放氢的平台压力升高，放氢量则增大。     

Ni对V55Ti20．5Cr18．1Fe6．4合金吸放氢性能的影响

研究了用Ni元素取代一定量V对V55Ti20．5Cr18．1Fe6．4合金结构与性能的影响。结果表明，随Ni含量的增加，合金有效吸氢量先增大后减小，放氢压力增大，合金吸氢动力学性能也是先有所改善，而后又变差。添加0．1at％Ni有利于改善基体合金V55Ti20．5Cr18．1Fe6．4的吸放氢性能。用Ni元素取代V引起的晶胞体积的变化、放氢平台压力的升高以及杂质相的出现，是影响合金有效吸氢量和吸氢动力学性能的主要因素。     

成份调整对V-Ti-Cr-Fe合金吸放氢性能的影响

分别调整Ti／Cr比及V含量，对V-Ti-Cr-Fe系四元合金的室温吸放氢性能进行了研究。结果表明：随V30Ti31＋xCr29-xFe10合金中Ti／Cr增大，合金吸氢量增大，放氢平台压降低，Ti／Cr〉1．2时放氢量减小，298K最大吸氢量3．66％（质量），最大放氢量2．0％（质量）；随Vx（TiCrFe）100-x（Ti-Cr-Fe=7：5：2）中V含量增大，合金吸氢量增大，放氢量增大，放氢平台压降低，V含量20％（原子）的合金中出现Laves相，298K最大吸氢量3．73％（质量），最大放氢量2．08％（质量）。     

贮氢合金La0.65Mg0.35Nix（x=3.0～3.5）高温电化学性能的研究

研究了La0.65Mg0.35Nix（x=3.0、3.1、3.2、3.3、3.4、3.5）稀土镁基贮氢合金电极的高温（333 K）放电性能。该系列合金电极在70 mA.g1放电电流密度下的高温放电容量随Ni含量的增加逐渐降低,x=3.0的合金在333K的放电容量（293.4 mAh.g-1）可以达到常温（298 K）放电容量的97.8%。333 K的电化学P-C-T曲线测试结果表明,随着Ni含量的增加,放氢平台明显变窄,吸/放氢平台的滞后增加,说明Ni含量的增加不利于改善合金电极的放电性能。腐蚀曲线测量结果表明,随着Ni含量的增加,合金的抗腐蚀性能逐渐减弱。     

TiV0.8-xCr1.2Alx合金的结构与贮氢性能

研究了Al对TiV0.8-xCr1.2Alx(x=0、0.05、0.1、0.15、0.2)合金的结构与贮氢性能的影响.XRD、PCT等测试研究表明:TiV0.8-xCr1.2Alx合金均为单相bcc结构,铸态时主相为树枝状晶组织;随着Al含量由0增加到6.67 at%,合金的晶格常数变大,吸氢量和放氢量减小,氢化物标准生成焓变与生成熵变增大.放氢的平台压随着Al含量的增加而线性增大.TiV0.75Cr1.2Al0.05合金最大吸氢量达3.887%(质量分数),有效吸氢量达2.288%.     

Studies on the hydrogen absorption properties of LaNi5−xSnx and La0.95Ni4.6Sn0.3 alloys using magnetic and thermoelectric power measurement

Magnetic and thermoelectric power (TEP) measurements are used to quantify hydrogen availability, absorption, and desorption in materials for nickel-hydride batteries and hydrogen storage. The effect of the concentration of conduction electrons is introduced and used to investigate hydride properties of these alloys. To investigate hydrogenation properties the calculated average number ofd-band electrons in hydrogen storage material is related to the measured thermoelectric power. Also, a thermodynamic exprssion of equilibrium is applied to demonstrate the relationship between the TEP and the activity of hydrogen for hydrogen adsorption. Magnetization decreases with increasing absorbed hydrogen in the stoichiometric LaNi_4.78Sn_0.22 alloy. However, magnetization increases with increasing hydrogen content in the nonstoichiometric La_0.95Ni_4.6Sn_0.3 alloy. The TEP for the stoichiometric LaNi_4.78Sn_0.22 alloy monotonically increases as a function of hydrogen content. However, the TEP of the nonstoichiometric La_0.95Ni_4.6Sn_0.3 alloy decreases as hydrogen content increases.     

Mg—Ni基贮氢合金元素取代改性研究进展

本文综述了近年来Mg—Ni基贮氢合金元素替代发展状况。元索取代影响Mg—Ni基贮氢合金贮氢量、吸放氢温度等吸放氢性能,改善Mg-Ni合金的电化学容量、活化性能、循环稳定性等电化学性能。对此,提出了合金需要解决的问题。     

Electrocatalytic activity and electrochemical hydrogen storage of Ni-La alloy prepared by electrodeposition from aqueous electrolyte

Ni-La alloy coating was prepared by electrodeposition. The effect of cathodic current density on the La content of the alloy coatings was discussed. It is found that the content of La in the alloy increases with increasing the cathodic current density. The microstructures and codeposition mechanism of Ni-La alloy coatings were investigated by means of X-ray diffraction (XRD) and cyclic voltammetry (CV). The results demonstrate that the Ni-La alloy is FCC and codeposited by the induced mechanism. The hydrogen evolution reaction (HER) on the electrodeposited Ni-La alloy electrodes in alkaline solution was evaluated by Tafel polarization curves. It is found that La-Ni alloy coating exhibites much higher exchange current density for HER than pure Ni electrode, and that the exchange current density increases with increasing the La content of alloys. The good electrocatalytic activity for HER of this Ni-La alloy is attributed to the synergism of the electronic structure of La and Ni. The electrodeposited La-Ni alloys have a certain dectrochemical hydrogen storage capacity of 34- 143 mAh/g, which increases with increasing the La content of alloys.     

Hydrogen embrittlement behavior induced by dynamic martensite transformation of Ni–Ti superelastic alloy

The hydrogen embrittlement behavior induced by the martensite transformation of Ni–Ti superelastic alloy subjected to a dynamic cyclic tensile test with hydrogen cathodic charging has been investigated by hydrogen thermal desorption analysis. The critical stress for the martensite transformation steeply decreases with increasing number of deformation cycles, whereas the critical stress for the reverse transformation only slightly changes. The dynamic stress-induced martensite transformation markedly enhances hydrogen absorption, compared with that of the martensite phase itself. The hydrogen concentration at the surface layer of the specimen is evaluated to be above 3500 mass ppm; nevertheless, no fracture associated with the stress-induced martensite transformation occurs. In addition, no hardening is observed at the surface layer of the specimen despite the formation of the hydride and hydrogen enrichment. The hydrogen thermally desorbed at a low temperature markedly increases, indicating that the hydrogen states are changed by the dynamic martensite transformation. Note that interactions between hydrogen and the phase transformation are probably irreversible, although the phase transformation is reversible. The present study shows, for the first time, that the hydrogen embrittlement behavior of the alloy strongly depends on the dynamic change of the hydrogen states accompanied by the martensite transformation.     

V含量对低钒Ti-V-Cr储氢合金储氢性能的影响

研究了V含量由5at%升高到35at%时,Ti-V-Cr储氢合金组织、相结构及储氢性能的变化.SEM及XRD结果显示:V含量为5at%的Ti-V-Cr合金由Cr1.97Ti1.07相和Cr2Ti相及很少量的Ti相组成;V含量为10at%的Ti-V-Cr合金除了包含前述的3相外还出现了一定量的V基bcc固溶体相;而V含量为35at%的Ti-V-Cr合金转变为以V基bcc固溶体为主相的固溶体储氢合金.随着V含量的升高和组织结构的变化,Ti-V-Cr合金最大吸氢量升高,放氢率也增大,但是吸氢速率显著减小,活化性能变差.室温下,V含量为35at%的合金具有最大的吸氢量并且放氢率也最高,最大储氢量和放氢率分别是2.86%(质量分数)和61%.     

Hydrogen storage properties of Zr1-xTixCo intermetallic compound

The intermetallic compound Zr1-xTixCo was prepared and its suitability for hydrogen storage was investigated.The alloys obtained by magnetic levitation melting with the composition of Zr1-xTixCo (x=0, 0.1, 0.2 and 0.3, at.%) show single cubic phase by X-ray diffraction.A single sloping plateau was observed on each isothermal, and pressure-composition-temperature (PCT) measurement results show that the equilibrium hydrogen desorption pressure of Zr1-xTixCo alloy increases with increasing Ti content.The desorption temperatures for supplying 100 kPa hydrogen are about 665, 642, 621 and 614 K for ZrCo, Zr0.9Ti0.1Co, Zr0.8Ti0.2Co and Zr0.7Ti0.3Co alloy, respectively.Repeated hydrogen absorption and desorption cycles do not generate separated ZrCo, TiCo and ZrH2 phases, indicating that alloys have good thermal and hydrogen stabilization.