压力-成分-温度试验装置及测试方法

根据贮氢合金气态吸放氢性能及其热力学参数测定标准，自制了测试装置，并且研究了压力-成分-温度曲线的测定和计算方法．通过对TiFe0.8Mn0.2合金的性能测试，证明了测试结果是可信的．同时也证明Ti-Fe0.8Mn0.2合金具有较好吸放氢性能和动力学性能．     

贮氢合金热力学测试装置及测试方法的研究

通过对贮氢合金热力学主要研究内容的分析，研究了贮氢合金热力学的ｐ－Ｃ－Ｔ曲线的测定和计算方法，并通过对ＬａＮｉ＿５合金的性能测试，证明了该合金具有良好的活化性能和吸氢性能，在３０℃常温下吸氢平衡压仅为０．２８ＭＰａ，吸氢量（Ｈ／Ｍ）可达１，吸放氢反应热焓达３１．９ＫＪ／ｍｏｌ。     

富镧混合稀土镍铝系合金贮氢特性的研究

本文研究了以富镧混合稀土(简称Ml)为吸氢元素组成的MlNi_(5-x)M_x(M为Al等合金元素)合金的贮氢特性。测定了试验合金在不同温度下的等温线和动力学曲线及吸、放氢前后的品格常数的变化,计算出该合金氢化物的热焓和熵变,并就主要贮氢特性与MlNi_5和LaNi_5比较,说明本合金只有一系列的优点,特別是抗中毒和再生性能优良,是一种很有价值的贮氢合金。     

机械合金化Mg2Ni储氢材料的吸氢动力学实验研究

为了研究压力和温度对Mg2Ni储氢合金动力学性能的影响以及吸氢反应机理,采用机械合金化的方法制备了Mg2Ni储氢合金。利用P-C-T测试仪进行活化并测试其吸氢动力学特性,并在实验的基础上结合3种常用的动力学模型分析了Mg2Ni合金吸氢反应的控速步骤。结果表明:Mg2Ni合金在673K、7.4MPa条件下活化3次就能够基本活化完全,吸收1mol氢气所需活化能为43.47kJ;温度对其动力学性能影响不明显,相反压力的影响比较大,吸氢反应速率和吸氢量都随压力的升高而增加;实验结果与JDM和JMA动力学模型比较吻合;金属氢化物形核长大与氢原子在产物层中的扩散过程是Mg2Ni合金吸氢反应的混合控速步骤。     

放电等离子烧结制备Mg2-xNdxNi（x=0～0.3）储氢合金

采用放电等离子烧结(SPS)工艺制备了Mg2-xNdxNi(x=0,0.1,0.2,0.3)储氢合金.通过X射线衍射(XRD)和扫描电镜(SEM)研究了合金的相结构和表面形貌,利用等容压差法分析测试了合金的压力--组成--温度(PCT)曲线和吸放氢动力学性能,研究了烧结温度、稀土元素Nd对储氢合金微观组织结构和储氢性能的影响,比较了SPS技术与真空感应熔炼法制备的Mg基合金组织结构和储氢性能的异同.结果表明:SPS制备的Mg2-xNdxNi(x=0～0.3)系列储氢合金具有多相结构,储氢合金的吸放氢动力学性能良好;Nd元素有利于Mg合金化,不利于储氢量;烧结温度对储氢量、PCT曲线平台性能有明显影响;当Mg2-xNdxNi系合金中含有Mg和NdMg12相,PCT曲线出现双平台现象;与铸态合金相比,SPS制备的Mg1.7Nd0.3Ni储氢合金的吸放氢动力学性能较好,但储氢容量、放氢率和PCT曲线平台性能更差.     

Zr-Hf-Co合金储氢性能研究

研究了Hf部分替代Zr对Zr-Hf-Co合金储放氢性能的影响,结果表明:Zr-Hf-Co合金保持原始Zr-Co合金单一的立方相结构,且Hf含量变化对合金晶胞体积影响不大;随Hf替代量增加,Zr-Hf-Co合金的放氢平台压升高,100 kPa平衡放氢压力对应的放氢温度显著降低,由Zr-Co合金的673 K降低到Zr0.7Hf0.3Co合金的618 K;热力学计算结果得到Zr-Hf-Co合金的放氢反应焓变ΔH随Hf替代量增加而降低,表明Zr-Hf-Co合金氢化物的稳定性降低,有利于合金在较低温度下放氢;合金的最大吸氢量随Hf替代量增加而略有降低,但吸氢动力学性能变化不明显.     

四元镧系吸氢合金的制备与性质研究

用共沉淀还原扩散法成功地制备了新的镧系吸氢合金ＬａＮｉ４Ｃｕ１－ｘＭｎｘ（ｘ＝０．２５，０．５，０．７５），对合金进行了ＸＲＤ、ＳＥＭ、吸氢测试和热力学研究，结果表明，这些合金易活化，吸氢容量较高，其氢化物的稳定性与合金的晶胞体积之间存在线性关系，这种关系对预测氢化物稳定性有一定的指导意义。     

Mg-Cr-Mn合金的组织结构与贮氢性能

Mg的吸放氢条件苛刻、动力学性能差，只有对它进行合金化，才能得到贮氢性能优异的 Mg合金。本研究尝试用 Cr-Mn元素对 Mg进行合金化，用不同工艺方法制备 Mg-Cr-Mn 合金，并用 X 射线衍射、扫描电子显微镜和能谱仪对合金进行了物相、形貌和成分表征，利用 Sieverts加氢装置对部分合金进行充氢试验。研究结果表明：Mg-Cr-Mn没有形成 Laves相，Mg只是少量地固溶在 CrMn合金立方相中。Mg-Cr-Mn合金在107 kPa、240℃下可少量吸氢。     

V-Ti-Cr系储氢合金吸氢动力学机制研究

通过试验测试及动力学方程计算,研究了(TiCr)1-xVx(x=0.05,0.10,0.35)V-Ti-Cr系合金吸氢动力学机制.结果显示,随着钒含量的增加,合金由莱维氏单相结构逐渐转变为莱维氏相和低钒含量的体心立方(BCC)固溶体两相结构,最终转变为高钒含量的BCC固溶体单相结构.相应地,其吸氢机制也由化学反应控制,逐渐转变为形核长大机制,最终转变为三维扩散机制.相结构的变化同吸氢机制的变化有一定的对应关系,吸氢动力学机制不同,表现出吸氢速率不同,化学反应控制的吸氢过程速度较快,三维扩散机制控制的吸氢过程速度较慢.     

镧镍铜锰吸氢合金的制备与表面性质

用共沉淀还原扩散法制备了新的镧系吸氢合金ＬａＮｉ４Ｃｎ０．５Ｍｎ０．５，借助ＸＰＳ技术研究合金的表面偏析等性质，确定了合金表面的化学组成，讨论了合金在空气中暴露程度对表面性质的影响以及表面性质对合金吸氢性能的影响，并结合吸氢测试研究了合金的活化，提出了ＬａＮｉ４Ｃｕ０．５Ｍｎ０．５的活化机制。     

Hydrogen absorption behavior of TA15 alloy

The hydrogen absorption kinetics of TA15 titanium alloy at 973–1123 K was studied using a tube-type hydrogen treatment furnace. The hydrogen absorption kinetic curves obtained were analyzed according to a series of mechanism equations to reveal the kinetic parameters and mechanism of the hydrogen absorption process. The results show that both the hydrogen absorption rate and the equilibrium hydrogen pressure increase and the time to reach equilibrium is shortened with increasing temperature. It is found that only the second hydrogen absorption period exists in the hydrogen absorption process of TA15 alloy between 973 and 1123 K, and the activation energy is 54.889 kJ/mol for hydrogen absorption. X-ray diffraction (XRD) and scanning electron microscopy (SEM) results demonstrate that δ hydride forms between 973 and 1123 K, and β phase decreases with the increase of temperature. Orthorhombic α″ martensite is generated at 1073-1123 K, and their amount increases with increasing temperature.     

Structural characteristics and mechanism of hydrogen-induced disproportionation of the ZrCo alloy

The intermetallic compound ZrCo was prepared, and its hydrogen-induced disproportionation in hydrogen desorption processes was investigated. The hydrogenation-dehydrogenation thermodynamics of the ZrCo alloy was evaluated by pressure-composition isotherm measurements at different temperatures. The kinetic processes of hydrogen-induced disproportionation at different temperatures under certain pressures were detailedly studied. The disproportionation rate of the ZrCo alloy increased with the increases of temperature and initial hydrogen pressure under experimental conditions. However, the maximum attainable extent of disproportionation did not change much with an increase in temperature or initial hydrogen pressure. The crystallographic structure analysis of the ZrCo alloy combining with its corresponding dehydrogenation kinetic curves under the conditions of an initial hydrogen pressure of 0.2 MPa and a temperature of 723 K indicated that the basic process of disproportionation reactions was composed of four stages:rapid dehydrogenation of ZrCoH₃, equilibrium of dehydrogenation, simultaneity of dehydrogenation and disproportionation, and completion of disproportionation.     

Effect of heat treatment on hydrogen storage properties and thermal stability of V68Ti20Cr12 alloy

Effect of heat treatment on the crystal structure, microstructure, hydrogen storage properties and thermal stability of V68Ti20Cr12 alloy prepared by arc-melting was studied in this work. It was found that both the as-cast and annealed (973 K/72 h) V68Ti20Cr12 alloys consisted of a single body-centered cubic (bcc) phase. After heat treatment, the hydrogen absorption/desorption kinetic characteristics of the as-cast alloy was improved greatly due to the homogeneous composition and perfect structure. The mechanism of hydrogen absorption/desorption process in the as-cast and annealed alloys was further investigated according to the Johnson-Mehl-Avrami (JMA) equation. The hydrogen absorption process of the as-cast and annealed alloys would be controlled by the one-dimensional diffusion process, while the hydrogen desorption process in the as-cast and annealed alloys was dominated by the geometrical contraction model. The pressure-composition-temperature (PCT) measurements show that the plateau pressure of the annealed alloy becomes comparatively flat. Furthermore, the activation energies of the dehydrogenation in the as-cast and annealed alloys were calculated using the Kissinger method, indicating that heat treatment is a very beneficial way to improve hydrogen absorption/desorption kinetics of the alloy.     

Microstructural characterization and hydrogenation performance of Zr_xV_5Fe(x=3-9) alloys

Zr_xV_5 Fe(x=3,5,7,8,9) alloys were designed to investigate the influence of Zr addition on hydrogenation performance.The alloys were prepared by arc melting and then annealed at 1273 K for 168 h.The results showed that the alloys were composed of α-Zr and C15-ZrV2 phases.The cell volume of C15-ZrV_2 phase firstly increased and then decreased as the content of Zr increased,while the reversed trend was found for the cell volume of α-Zr phase,which was related to the stoichiometric ratio of elements.α-Zr phase distributed in C15-ZrV2 phase matrix in Zr_xV_5 Fe(x=5,7,8,9) alloys,among which Zr7 V5 Fe alloy showed the best distribution.The PCT curves of the alloys under 623 K,673 K and 723 K showed that the hydrogen absorption plateau pressure of the phases in different alloys decreased gradually with the increasing content of Zr.However C15-ZrV2 phase in Zr7 V5 Fe alloy had the lowest hydrogen absorption plateau pressure at room temperature,which was consistent with the change tendency of the corresponding cell volume.Moreover,the kinetic curves of hydrogen absorption at 623 K revealed that Zr7 V5 Fe alloy with the smallest average particle size and the largest phase boundary area showed the fastest hydrogen absorption kinetics.Compared with other four alloys(including St707 alloy),Zr_7 V_5 Fe alloy is more suitable for the use of getter.     

TC4钛合金压坯的吸氢行为

利用管式氢处理炉研究了TC4钛合金压坯的温度-平衡氢分压关系以及吸氢动力学行为,测定了吸氢速率常数和激活能,并分析了吸氢反应各个阶段的反应机理.结果表明,随着吸氢温度的升高,达到平衡所需要的时间缩短,吸氢后的平衡氢分压升高.在350℃吸氢时,反应机制分别是形核长大、幂函数定律和三维扩散.在400℃吸氢时,反应机制分别是幂函数定律和三维扩散.在450～750℃吸氢时,反应机制均是三维扩散.TC4钛合金压坯吸氢反应的激活能为14.55kJ·mol-1.     

减压试样密度法预测铝合金铸件的氢针孔度

利用砂型样杯取代传统的金属型样环制作了铝合金减压凝固试样，结果表明，该试样可以预测名合金铸件的氢针也级别，控制铝事金的熔炼质量，测试仪器中还设置了预真空室，可使凝固室 厚短的时间内达到预定的真空度，提高测试精度，在试验还发现合适的砂型压凝固压力约为１．１３ｋＰａ。     

TiFe基储氢合金的BaZrO3坩埚熔炼制备及其储氢性能

利用自制25 kg 级BaZrO3坩埚,通过ZG-0．05型真空感应熔炼制备 TiFe 基储氢合金。熔炼条件为：0．6 MPa氩气保护气氛,精炼时间5～10 min,精炼温度1450℃左右。采用ICP原子发射光谱分析仪分析所熔合金的化学成分,利用金相显微镜、扫描电子显微镜、XRD 衍射仪研究了合金的金相组织、表面形貌、微区元素分布、物相结构,用气体反应控制器测定了合金的PCT曲线。研究表明：由BaZrO3坩埚熔炼的TiFe基储氢合金氧质量分数与石墨坩埚熔炼的合金氧质量分数均小于0．1％,而石墨坩埚熔炼的合金碳质量分数为0．417％。BaZrO3坩埚熔炼后的合金完全由等轴晶构成,而石墨坩埚熔炼后的合金则由等轴晶组织和在晶粒内或沿晶界分布的球形TiC颗粒组成。BaZrO3坩埚所熔炼的合金不仅最大吸氢量比石墨坩埚熔炼的合金的最大吸氢量大,而且吸放氢平台压力也低。     

LaNi4.25Al0.75储氢合金的改性

为了提高LaNi4．25Al0．75合金的储氢性能,采用退火、表面镀铜和表面包覆SiO2对合金进行改性,并对处理前、后合金的微观结构和吸放氢性能的变化进行研究。研究结果表明,退火消除了LaNi4．25Al0．75合金中的偏析,减少了内应力,使合金具有平坦的吸氢平台;表面镀铜处理加快了合金的吸、放氢速度,但吸氢含量略有降低,另外,镀铜合金抗粉化性能加强,经10次吸、放氢循环后没有出现粉化现象;表面包覆SiO2前、后,合金的吸氢量变化不大,抗粉化性能加强,经10次吸、放氢循环后没有出现粉化现象。     

Kinetics of the hydrogen absorption and desorption processes of hydrogen storage alloys: A review

High hydrogen absorption and desorption rates are two significant index parameters for the applications of hydrogen storage tanks.The analysis of the hydrogen absorption and desorption behavior using the isothermal kinetic models is an efficient way to investigate the kinetic mechanism.Multitudinous kinetic models have been developed to describe the kinetic process.However,these kinetic models were de-duced based on some assumptions and only appropriate for specific kinetic measurement methods and rate-controlling steps(RCSs),which sometimes lead to confusion during application.The kinetic analysis procedures using these kinetic models,as well as the key kinetic parameters,are unclear for many researchers who are unfamiliar with this field.These problems will prevent the kinetic models and their analysis methods from revealing the kinetic mechanism of hydrogen storage alloys.Thus,this review mainly focuses on the summarization of kinetic models based on different kinetic measurement methods and RCSs for the chemisorption,surface penetration,diffusion of hydrogen,nucleation and growth,and chemical reaction processes.The analysis procedures of kinetic experimental data are expounded,as well as the effects of temperature,hydrogen pressure,and particle radius.The applications of the kinetic models for different hydrogen storage alloys are also introduced.     

RMg2Ni9(R=Ca,La)合金的电子结构与稳定性的第一原理研究

利用第一原理赝势平面波方法计算了C aM g2N i9,L aM g2N i9贮氢合金的电子结构,分析了合金中原子间的相互作用以及对合金稳定性的影响.结果表明:L aM g2N i9中N i-N i间的作用比C aM g2N i9中相应的原子间的作用强,使得C aM g2N i9比L aM g2N i9易于完成由N i-N i键到N i-H的转移,是导致L aM g2N i9合金吸氢量比C aM g2N i9合金吸氢量少的原因之一.