钛基非蒸散型吸气剂的性能研究

研究了不同成分经相同工艺制成的钛基烧结体非蒸散型吸气剂的性能。测试了钛基吸气剂在3种激活工艺下的室温吸氢性能，并将它们与传统同类型高温激活Zr-C吸气剂的室温吸氢性能作了对比。同时对钛基吸气剂进行了形貌观察、孔隙度测试和强度测试。结果表明，这种新型的钛基吸气剂在低温激活时的室温吸氢性能优于高温激活的传统Zr-C吸气剂，随着激活温度的升高，新型吸气剂的性能更好。此外，新型吸气剂抗振动性能很好，解决了传统吸气剂的掉粉问题。     

ZrCoRE吸气薄膜的膜层结构与性能研究

为了研究膜层结构对非蒸散型吸气薄膜性能的影响,运用射频磁控溅射法(RF magnetron sputtering)制备了ZrCoRE单层膜和双层膜,其中单层膜只含主体层,双层膜含有主体层和附着层。采用扫描电子显微镜(SEM)、原子力显微镜(AFM)、X射线衍射法(XRD)表征了薄膜的形貌和结构,利用ASTM F798-97"动态法"测试了薄膜的吸气性能。结果表明,ZrCoRE薄膜的主体层在较高沉积压强(4 Pa)下受到原子阴影效应与沉积原子低迁移率的作用而形成柱状组织,附着层在较低沉积压强下(0.2 Pa)由于沉积原子迁移率高而形成致密组织,附着层的存在使主体层柱状组织实现连续生长;主体层表面为20 nm的颗粒无序堆积态,形成了大量的表/界面缺陷;通过高频感应在300℃下激活30 min,在2.7×10-4Pa的H2压强下,薄膜的室温吸气速率在1～100 cm3·s-·1cm-2范围内变化;双层膜吸气速率是单层膜的10倍,3 h的吸气量达80 Pa·cm3·cm-2;吸气薄膜的大活性比表面积和高扩散速率,使其单位质量吸气量达104Pa·cm3·g-1量级以上,高于块体吸气剂的103Pa·cm3·g-1量级,附着层的存在提高了主体层的吸气性能。     

多孔Ti吸气材料的制备及吸氢性能研究

利用粉末冶金法,以电真空Ti粉为原料,并添加造孔剂NH_4HCO_3,制备了多孔Ti吸气材料。通过扫描电镜(SEM)对吸气材料进行微观形貌观察,利用阿基米德排水法测试吸气材料的孔隙度,用动态流导法分别测试不同NH_4HCO_3添加量的吸气材料在450和700℃激活下的吸氢性能。结果表明,引入造孔剂NH_4HCO_3后,可以成功制备出有多孔结构的Ti烧结体,且样品的孔隙率随NH_4HCO_3含量的增加近似呈线性关系,当造孔剂质量分数为30%时,孔隙率达到61%;随着NH_4HCO_3含量的提高,样品的吸气性能呈现出先升高后降低的趋势;450℃激活时,添加20%(质量分数)NH_4HCO_3样品的特征吸氢速率S_(10)是未添加NH_4HCO_3样品的6.3倍;700℃激活时,添加25%(质量分数)NH_4HCO_3样品的特征吸氢速率S_(10)是未添加NH_4HCO_3样品的2.7倍;同一成分的样品,在700℃激活下的吸氢性能优于450℃激活下的性能。     

吸氢对HDDR各向异性NdFeB材料的影响

对d HDDR方法制备各向异性Nd1 3FebalB7Co1 1 Zr0 .1 磁粉过程中吸氢处理阶段进行了研究。发现在 933K左右的温度范围内 ,氢压为 0 .1MPa的条件下进行低温吸氢 ,材料发生了剧烈的歧化分解 ,导致材料的各向异性消失 ,这在处理过程中是应避免的 ;而在 373～ 833K温度范围内进行低温吸氢时 ,材料具有优异的磁性能 ,特别是在 473～ 573K时 ,低温吸氢处理过程有明显的细化粉末颗粒的作用。吸氢时间对材料磁性能几乎没有影响。升温过程中保持合适的氢分压既可以避免材料发生剧烈的歧化反应而破坏了磁各向异性 ,又有利于提高材料的矫顽力 ,从而制备具有高性能的各向异性NdFeB材料。当升温过程中的氢压保持在 0 .0 6MPa时 ,最终可以制得矫顽力和各向异性均较好的磁粉 ,其磁体的性能为 :Br=0 .887T ,iHc=885kA·m- 1 ,DOA =0 .61 ,(BH) max=1 2 5kJ·m- 3。     

宽温型AB5储氢合金结构及其电化学性能研究

用高频感应熔炼法制备了Mm(NiCoAlMn)5储氢合金,采用模拟电池法测试了合金在238～323 K温度范围内的活化、放电容量和高倍率放电性能.结果表明:制备合金为典型AB5型储氢合金,303K温度条件下吸氢量达到1.38％(质量分数),氢化物生成焓为32.36 kJ ·mol-1H2.合金电极的活化性能、放电容量和高倍率性能受温度影响显著.室温预活化可有效改善电极的低温性能,经室温预活化后合金电极在238 K最大放电容量达到336 mAh·g -1,明显高于未经室温预活化的最大放电容量25 mAh·g-1.Mm(NiCoMn)5贮氢合金电极的高倍率性能随着温度的升高先升高后降低,273和303 K温度条件下合金保持高倍率性能良好,3C放电电流密度条件下容量保持率均高于80％;238 K温度条件下合金的大电流放电性能急剧降低,1C放电电流密度条件下容量保持率仅为10％; 273 K下合金电极的综合性能最佳,最大放电容量达到340 mAh·g-1,300 mA·g-1放电电流密度下的高倍率放电比率为86％.循环伏安法测试证实,在238～323 K范围内,电极的氧化峰峰值电流(Ip)与扫描速度的平方根(v1/2)之间均存在良好的线性关系,整个电极反应受氢原子扩散控制;随着温度的降低氢扩散系数急剧下降,从而导致该合金电极的低温高倍率放电性能变差.由Arrhenius公式计算出合金中的氢扩散活化能为10.56 kJ·mol -1.     

镁碳纳米储氢材料的制备及其性能的研究

用镁与炭化无烟煤混合后进行充氢球磨的方法,制备镁碳储氢材料。运用扫描电镜和透射电镜对储氢材料的粒径、微观形貌及晶形结构进行了表征,运用热重分析仪和差示扫描量热仪对材料的吸放氢性能进行了测试。实验发现,在镁中添加碳进行充氢球磨时,可以在5h内使粒径达到50-100nm。随着碳添加量的增大,镁碳储氢材料的储氢量下降,放氢温度升高。材料Mg3.0C2.0(碳添加量40%)的储氢量2.61%,放氢温度295℃。活性金属Mo对镁碳材料吸放氢性能有着明显的改善作用。     

以金属铁粉为原料磷酸铁锂的制备和性能研究

以1~3μm金属铁粉和磷酸二氢锂为原料,采用高温固相法合成了无碳磷酸铁锂。通过X射线衍射(XRD),扫描电镜(SEM)和电化学测试等方法对合成的磷酸铁锂材料的结构、形貌和电化学性能进行了表征。研究结果表明,采用1~3μm的金属铁粉和磷酸二氢锂为原料,高温固相法合成了具有橄榄石晶体结构的磷酸铁锂材料,粉末近似球形,振实密度较高,一次颗粒200~300 nm。600℃合成的磷酸铁锂存在杂质相,650~750℃下合成的磷酸铁锂具有完整的橄榄石晶体结构,产物为纯相。无碳的磷酸铁锂呈浅灰色,600~750℃下合成的磷酸铁锂材料0.1C充放电存在平台,显示两相充放电特性,比容量均在100 mAh·g-1左右,且极化较大。用蔗糖对其进行包覆改性得到碳包磷酸铁锂,其颜色呈黑色,改性后的磷酸铁锂电化学性能有了较大的提高,0.1C比容量达到了154 mAh·g-1,充电平台和放电平台之间的极化明显降低,具有较好的循环稳定性。     

化学镀镍对Ti粉吸气性能的影响

采用低温碱性化学镀方法制备镍包覆钛复合细粉，利用XRD，SEM，EDS和吸气性能测试台对样品的相结构、表面形貌、表面成分和吸气性能进行分析和表征。结果表明：表面镍层以结晶态包覆于Ti表面，镀层均匀，镀层中的Ni对H2具有催化解离作用，促进了Ti的吸氢速率，在较低温度450℃激活时，镍包覆钛复合细粉的吸氢性能较纯Ti粉有了明显的提高。     

烧结温度对TiNi储氢合金电化学性能的影响

采用X射线衍射(XRD)分析,充放电测试,线性极化和电位阶跃等方法研究了在750,850,950℃3个不同温度下进行固相烧结对TiNi储氢合金的相结构和电化学性能的影响。结果表明:随着烧结温度的提高,TiNi合金最大放电容量由179.0 mAh.g-1增加到188.1和211.3 mAh.g-1。虽然温度的升高并没有提高合金的交换电流密度,但却大大增强了氢在合金中的扩散速率,扩散系数D从750℃的2.49×10-10cm2.s-1增加到850℃的2.61×10-10cm2.s-1和950℃的3.48×10-10cm2.s-1,从而显著的改善了合金电极的高倍率放电性能(HRD)。950℃烧结后的合金在1500 mA.g-1的放电电流下仍然可以放出84.6 mAh.g-1的电量。     

低碳钢Q345B大方坯热塑性研究

采用Gleeble 1500热模拟机对Q345B钢在1×10-4s-1和1×10-3s-1应变速率下的热塑性进行了研究。研究表明:在1×10-4s-1的应变速率下,试样在600～TL℃的温度范围内存在两个脆性区,即高温脆性区,为1 217～TL℃,低温脆性区,为600～930℃;在1×10-3s-1的应变速率下,试样在600～TL℃的温度范围内不存在高温脆性区,仅存在低温脆性区,为600～915℃。影响Q345B钢热塑性的主要因素是S偏析、应变速率、铁素体的析出以及细小的AlN粒子的析出。     

纳米晶锆粉对材料吸气性能的影响

采用高能球磨的方法制备出纳米级超细锆粉，并将细化锆粉应用在吸气材料制备上。结果表明，经一定时间高能球磨后粉末粒度达到纳米级，粉末颗粒形状不规则，在球磨过程中有少量铁杂质带入。将球磨2h的锆粉应用在吸气材料制备上，发现能有效地提高材料的吸气速率和吸气容量，但粉末粒度过细反而使吸气性能下降。这为提高的吸气性能找到了全新的途径。     

Structure,properties, and production of Zial powder alloy for gas absorbers

Calcium-hydride production technology for Zial (Zr-16Al) alloy is developed. In contrast to powder obtained by the grinding of cast alloy, powder produced by calcium-hydride technology is more disperse, with a highly developed particle surface. A method is developed for determining the sorptional capacity of Zial alloy in hydrogen. It is found that Zial powder produced by calcium-hydride technology matches powder obtained from cast alloy in terms of hydrogen sorption and is preferable in terms of carbon-monoxide sorption. X-ray phase analysis shows that gas absorbers made from Zr-16 Al powder produced by the calcium-hydride technology consist mainly of intermetallics Zr₃Al₂, Zr₅Al₃, and Zr₄Al₃. This composition is optimal when using Zial alloy as a getter     

高能球磨法制备吸气材料用超细锆粉

采用高能球磨的方法制备出超细锆粉，并采用XRD，TEM，动态光散射粒度测试仪等多种测试手段研究了粉末的组成，形貌和粒度分布，结果表明，经20h高能球磨后粉末晶粒达到纳米级，粉末颗粒形状不规则，在球磨过程中有少量铁杂质带入，对试验结果进行了进一步的分析和讨论。     

Synthesis and characterization of mesostructured ceria-zirconia solid solution

Mesostructured Ce0.6Zr0.4O2 solid solutions were synthesized by coprecipitation combined with evaporation-induced self-assembly process. The obtained materials were characterized by X-ray diffractometer (XRD), Raman, transmission electron microscopy (TEM), N2 sorption, and hydrogen temperature programmed reduction (H2-TPR). The results showed that the solid solutions consisted of uniform nanocrystals, which piled homogeneous mesopores of about 4 nm. Furthermore, different surfactants had little influence on the mesoporous structures. All these samples exhibited high thermal stability.     

低放氢压的Ti-Mn基Laves相贮氢合金

研究了Ti/Zr比与Mn/Cr比变化对Ti Mn基Laves相贮氢合金贮氢性能的影响 ,发现随Ti/Zr比降低 ,合金放氢压降低 ,贮氢量略微增加 ,平台坡度变陡 ;随Mn/Cr比降低 ,合金放氢压降低 ,平台区变短 ,但合金的贮氢量变化不大。Ti0 .85Zr0 .15Mn1.6-yCryV0 .32 Fe0 .0 8系列合金当 0 1≤y≤ 0 2时比较适宜作为小型燃料电池的氢源。     

TiZrNi准晶电化学储氢性能研究

准晶是一种结构特殊的固态有序相.其特殊的原子排列方式可能会使其具有较高的储氢性能.研究目的是获得Ti系准晶,并对其电化学储氢性能进行研究.采用铸造法炼制合金,准晶难以形成.因此采用首先通过机械合金化获得非平衡态合金,然后对非平衡态合金进行不同温度热处理来获得准晶的技术路线.采用机械合金化制备了Ti42.5 Zr42.5 Ni15非晶.在机械合金化过程中要注意气体保护,否则难以形成非晶.将非晶合金在530℃处理2h后,在基体中出现了准晶,此时的基体为准晶和晶态混合物,准晶占大部分.经750℃处理2h后,合金基体中只有晶态存在.对不同状态合金进行了电化学储氢特性测量.对于非晶、准晶、晶态三状态合金,其电化学储氢均存在一个活化过程.非晶态的容量最高,其次为准晶态,晶态最低.     

Influence of getter and gas atmosphere on the reduction kinetics of γ-Fe2O3, and on the phase composition and particle size of the reaction products

The kinetic features and mechanism of reduction of γ-Fe₂O₃ in hydrogen in the presence of CaO as a getter for the gaseous reaction products was studied. Data were obtained on the kinetic constants, reaction rate, and evolution of surface area during the reaction. It was established that the getter has a favorable effect on the degree of dispersion of the reaction products.     

Effects of a getter on nio reduction kinetics and metallic nickel particle formation

Studies have been made on the kinetics of nickel oxide powder reduction by hydrogen in the presence of calcium oxide as a water vapor getter. The getter influences the reduction mechanism and the coalescence of the reduced metal as well as the growth of fresh surface. Data are presented on the fresh surface of the nickel powder formed in the presence of calcium oxide and in the absence of it as regards reduction kinetics.Materials Science Institute, Ukrainian Academy of Sciences, Kiev. Translated from Poroshkovaya Metallurgiya, Nos. 5–6, pp. 79–83, May—June, 1996. Original article submitted June 29, 1994.     

Effect of Phase Composition and Activation of a Titanium Nickelide Surface by Electrochemical Cycling on Its Hydrogen Sorption Capacity

We have studied the electrochemical properties of electrodes based on the intermetallic TiNi, obtained by powder metallurgy, with an austenite and martensite structure. The electrochemical and capacity characteristics of the electrodes were determined from the charging curve under nonequilibrium conditions, and also from the cyclic voltammetric curve in alkaline medium. We have studied the structural and phase changes during absorption - desorption of hydrogen and the effect of the structure on activation and the hydrogen sorption capacity. We have shown that electrodes made from titanium nickelide with a two-phase structure (austenite, martensite) are easily activated and have a higher hydrogen capacity than electrodes with a single-phase austenite structure. __________ Translated from Poroshkovaya Metallurgiya, Nos. 7–8(444), pp. 99–106, July–August, 2005.     

NiO-Ce0.5Zr0.5O2 catalysts prepared by citric acid method for steam reforming of ethanol

NiO-Ce0.5Zr0.5O2catalysts were prepared by citrate method and used for hydrogen production from steam reforming of ethanol (SRE). The effect of nickel content and space velocity on the catalytic performance was investigated. The prepared catalysts were character-ized with XRD and thermal analysis techniques. 20%NiO-Ce0.5Zr0.5O2 catalyst was very active and selective for hydrogen production via SRE, in which ethanol conversion of 100% could be obtained with feed component of 20% (H2O+EtOH) and 80% N2, water/ethanol of 3/1 in molar ratio at 350 ℃. Also, the catalyst showed good stability for anti-sintering and carbon-resistance. The XRD illuminated that both NiO and Ce0.5Zr0.5O2 crystal sizes were very small in NiO-Ce0.5Zr0.5O2 catalyst, and Ce0.5Zr0.5O2 solid solution was formed.