C.H. Zhou
,
K. Yang and Y.X. Lu (Liaoning Key Lab for Hydrogen and Materich
,
Institute of Metal Research
,
The Chinese Academy of Sciences
,
Shenyan 110015
,
China)
金属学报(英文版)
In order to alleviate the severe interface reaction, which is likely to occur during the fabrication of continuous SiC fiber reinforced titanium matrix composite, hydrogen was temporarily introduced in the fabrication to lower the consolidation temperature of Ti/SiC composites in the present work. Effects of different fabrication conditions, with or without hydrogen, on the bonding state and the matrix microstructure were investigated. In-situ hydrogenation method was found to larpely improve the interface bonding of the composite, and full consolidation could be achieved at 750 or even 700° C more than 100°C lower than the normal fabrication temperature of Ti/SiC composite, which consequently reduced the interfacial reaction layer between Ti matrix and SiC fiber. Different hydrogenation condition led to different matrix microstructure. In order to avoid the embrittling effect of residual hydrogen on the composite,Ti/SiC composite needs to be held in vacuum at the fabrication temperature for longer time after consolidation.
关键词:
Ti/SiC composite
,
null
,
null
Physica B-Condensed Matter
The magnetic properties and magnetocaloric effect of Tb(1-x)Y(x)CoC(2) (x = 0, 0.1, 0.2, 0.3, 0.4) compounds have been investigated systematically. All the compounds undergo second-order transitions from paramagnetic to ferromagnetic states without thermal and magnetic hysteresis. With increasing Y content from 0 to 0.4, the Curie temperatures decrease nearly linearly from 28 to 18 K. The nature of the second-order phase transitions can be confirmed by Arrott plots. For Tb(0.6)Y(0.4)CoC(2) compound, the maximum value of the magnetic entropy change -Delta S(M) at 20 K is 9.35 J kg(-1) K(-1) for an external field change of 5T (5.14 J kg(-1) K(-1) for 2T). The large reversible magnetic entropy change makes Tb(0.6)Y(04)CoC(2) compound an attractive candidate for the application at hydrogen liquefaction temperature. (C) 2010 Elsevier B.V. All rights reserved.
关键词:
Curie temperature;Magnetocaloric effect;Magnetic properties;ac susceptibility
International Journal of Hydrogen Energy
Hydrogen absorption/desorption properties of La(0.2)Y(0.8)Ni(5-x)Mn(x) (x = 0.2, 0.3, 0.4) alloys for high-pressure hydrogen compression application were investigated systematically. The Pressure Composition isotherms and absorption kinetics were measured at 293, 303 and 313 K by the volumetric method. XRD analyses showed that all the investigated alloys presented CaCu(5) type hexagonal structure and the unit cell volume increased in both a and c lattice axes with Mn substitution. Hydrogen absorption/desorption measurements revealed that Mn could lower the plateau pressure effectively, improve the hydrogen storage capacity and absorption kinetics but slightly increase the slope of the pressure plateau and hysteresis. The study results suggest that La(0.2)Y(0.8)Ni(4.8)Mn(0.2) is suitable for the high-pressure stage compression of the hydrogen compressor and the other two alloys, La(0.2)Y(0.8)Ni(4.7)Mn(0.3) and La(0.2)Y(0.8)Ni(4.6)Mn(0.4), for the preliminary stage. (C) 2009 Professor T. Nejat Veziroglu. Published by Elsevier Ltd. All rights reserved.
关键词:
Hydrogen storage;Metal hydride;Hydrogen compressor;Pulverization;hysteresis;absorption;kinetics;hydrides;systems
张炳涛
,
滕冰
,
钟德高
,
曹丽凤
,
李建宏
,
人工晶体学报
采用提拉法生长出Ybb0.005Y0.708Lu0.287VO4晶体.在室温下,对Yb0.005Y0.708Lu0.287VO4晶体进行了XRPD测试,计算了晶格常数(a=b=0.7091 nm,c=0.6273 nm)和密度(4.826 g/cm3).对混晶的(100)面进行了腐蚀,腐蚀坑呈四棱锥形状.平均线膨胀系数α1=1.285×10-6 K-1,α3=7.030 ×10-6 K-1,温度在330.15 K和570.15 K之间变化时,比热为0.494 ～0.617 J/g·K.
关键词:
钒酸盐晶体
,
腐蚀坑
,
膨胀系数
,
比热
,
热导率
Chinese Journal of Chemical Physics
The hydrogen adsorption properties and uptake capacities of the A, X and ZSM-5 types of zeolites were investigated at temperatures of 77, 195 and 293 K and pressures up to 7 MPa, using a conventional volumetric adsorption apparatus. All hydrogen adsorption isotherms were basically type 1, but the maximum in isotherm, a unique feature of supercritical adsorption, was observed at high pressures of 2-5 MPa at 77 K. The isosteric heats of adsorption were determined from the isotherms and the factors that influence their variations were discussed. Different types of zeolites exhibited remarkably different hydrogen uptake, based on both the framework structure and the nature of the cations present. The highest gravimetric storage capacity of 2.55wt% was obtained for NaX-type zeolite at 4 MPa and 77 K. In CaA, NaX and ZSM-5 types of zeolites, hydrogen uptakes were proportional to the specific surface areas, which were associated with the available void volumes of the zeolites. A threshold in hydrogen adsorption observed in NaA and KA was attributed to a pore blocking effect by large cations in KA. A ratio of the kinetic diameter of adsorbate to the effective opening diameter of zeolite was used to judge the blocking effect for physisorption.
关键词:
zeolite;hydrogen storage;hydrogen adsorption;adsorption isotherm;gas-adsorption;storage;silicalite;nitrogen
孙丹丹
,
潘尚可
,
任国浩
,
吴云涛
,
商珊珊
,
张国庆
无机材料学报
doi:10.3724/SP.J.1077.2013.12735
针对Ce:Li6Lu(BO3)3晶体有效原子序数(zeff)高的问题,采用低原子序数的Y3+离子部分置换晶体中的Lu3+离子.通过固相合成法制备了Ce:Li6Lu1-xYx(BO3)3(0≤x≤1)固溶体.X射线粉末衍射(XRD)分析表明,该系列固溶体结构与Li6Gd(BO3)3晶体相同,空间群为P21/c.其X射线激发发射(XSL)的发光强度随着Y3+的含量增加而降低,当x=0.5时,固溶体的有效原子序数与Li6Gd(BO3)3闪烁体相当,但XSL发光强度是其1.4倍.Ce:Li6Lu0.5Y0.5(BO3)3的XSL光谱和PL光谱都在400 nm附近出现Ce3+离子的特征峰,可拟合出361和419 nm两个发光分量,分别对应于Ce3+离子的激发态电子的5d1→2F5/2和5d1→2F7/2能级跃迁.Ce:Li6Lu0.5Y0.5(BO3)3固溶体的衰减时间比Ce:Li6Lu(BO3)3略长,为19.6 ns.当x=0.50～0.70时,Ce:Li6Lu1-xYx(BO3)3(0≤x≤1)闪烁体比较适合作为中子探测材料.
关键词:
固相合成
,
Ce∶Li6LU1-xYx(BO3)3
,
X射线激发发射谱
,
PL光谱
,
衰减时间
Journal of Magnetism and Magnetic Materials
Magnetization curves of the ternary tetragonal compound Lu2Fe14C were measured in an extracting-sample magnetometer in the temperature range from 1.5 to 300 K. The temperature dependence of the magnetic properties of Lu2Fe14C is discussed.
关键词:
anisotropy
丁栋舟
,
陆晟
,
潘尚可
,
张卫东
,
王广东
,
任国浩
无机材料学报
doi:10.3724/SP.J.1077.2008.00434
采用提拉法制备了LuxY1-xAlO3:Ce晶体样品, 通过XRD物相分析和成分分析, 并结合Lu2O 3-Al2O3二元体系相图以及LuxY1-x AlO3:Ce结构稳定性方面的分析与讨论, 结果表明: 随着熔体中Lu元素含量的增加, 熔体分层加剧, 析晶LuxY1-xAlO3:Ce相的熔体组成区间将向富Lu一侧偏移, 这使得晶体上部易伴生(Lu,Y)3Al5O12:Ce相; 而随着Lu元素含量的提高, LuxY1-xAlO3:Ce晶体的热稳定性降低, 氧空位的存在则使晶体的热稳定性进一步降低, 在接种过程中籽晶表面易发生相分解反应生成(Lu,Y)3 Al5O12:Ce和(Lu,Y) 4 Al2O9:Ce, 籽晶表面相分解产物(Lu,Y)3Al5O12:Ce提供了诱导析晶(Lu,Y)3Al5O12 :Ce相所需的晶核, 这使得晶体的外
表面处易伴生(Lu,Y)3Al5O12:Ce相. 调整配料组成使 n(Lu,Y)2O3 ): n (Al2O3)=1.17～1.00, 加大熔体内部和固液界面处的温度梯度以改善熔体对流、抑制熔体分层以及籽晶表面处的相分解等有助于高Lu元素含量LuxY1-xAlO3 :Ce晶体的获得.
关键词:
铝酸钇镥晶体
,
perovskite
,
garnet
,
accompany
International Journal of Hydrogen Energy
Effects of the Mn substitution on microstructures and hydrogen absorption/desorption properties of LaNi(3 8)Al(1 2-x)Mn(x) (x = 0 2 0 4 0 6) hydrogen storage alloys were investigated The pressure composition (PC) isotherms and absorption kinetics were measured in a temperature range of 433 K <= T <= 473 K by the volumetric method XRD analyses showed that with the increase of the Mn content in the LaNi(3 8)Al(1 2-x)Mn(x) alloys the lattice parameter a was decreased c increased and the unit cell volume V reduced It was found that the absorption/desorption plateau pressure was increased and the hydrogen storage capacity was enhanced with the increase of Mn content The absorption/desorption plateau pressure of the alloys was linearly changed with the Mn content x and the lattice parameter a while the hydrogen storage capacity was linearly increased with the increase of c/a ratio It was also found that the slope factor S(f) was closely correlated with the lattice strain of the alloys (C) 2010 Professor T Nejat Veziroglu Published by Elsevier Ltd All rights reserved
关键词:
Metal hydride (A);Hydrogen absorbing materials (A);Gas solid reactions;(B);Thermodynamic properties (C);structural-properties;sorption properties;system;hydrides;lani5-xalx;ni
Journal of Alloys and Compounds
Hydrogen absorption/desorption properties of MmNi(4.5)Cr(0.5-x)Zr(x) alloys ( x = 0, 0.05, 0.1) were investigated in the present work. The Pressure-Composition ( PC) isotherms and absorption kinetics were measured in the temperature range of 273 <= T <= 303 K by the volumetric method. XRD patterns showed that the as-annealed MmNi(4.5)Cr(0.5-x)Zr(x) alloys had CaCu(5) type hexagonal structure and could keep the same single phase after 16 cycles of absorption/desorption. It was found that with the increase of x in MmNi(4.5)Cr(0.5-x)Zr(x) alloys, the dissociation plateau pressure increased, the hysteresis was diminished, the hydrogen uptake capacity was reduced and the absorption kinetics was improved. The absorption plateau pressure increased when x was increased to 0.05, but decreased when x increased to 0.1. It was also found that the dissociation plateau pressure increased linearly with increasing cell volume V and the lattice parameter a, and the hydrogen uptake capacity decreased linearly with increasing Zr content. (c) 2008 Elsevier B.V. All rights reserved.
关键词:
Metal hydride;Hydrogen absorbing materials;Gas-solid reactions;Thermodynamic properties;absorption-desorption characteristics;storage properties;intermetallic;compounds;hydriding properties;mischmetal;system;ni;improvement;aluminum;mmni5
