The pressure isotherms of the ZrCr2–H system (20–200 °C, 10–700 Torr) and powder X-ray diffraction have shown the occurrence of two phases, cubic ZrCr2Hx (x<1.0) and hexagonal ZrCr2Hx (2.5
ZrCr2-H 体系(20-200 °C,10-700 托)的压力等温线和粉末 X 射线衍射表明存在两种相:立方 ZrCr2Hx(x<1.0)和六方 ZrCr2Hx(2.5
Investigation of various reactions for the direct synthesis of TiCr2 intermetallic compound from the TiO2–Cr2O3–Ca system
作者:O. Bayat、A.R. Khavandi、R. Ghasemzadeh
DOI:10.1016/j.jallcom.2011.12.174
日期:2012.4
indicates the formation of a solid solution formation by the reaction of TiO 2 with Cr 2 O 3 . As the temperature increased to about 950 °C the Ca started to melt (at approximately 847 °C) resulting to an exothermic peak due to the reaction of Ca with Cr 2 O 3 forming Cr metal. The formation of CaTiO 3 formed by the reaction of CaO with TiO 2 decreased the amount of TiO 2 in the mixture of starting materials
摘要 利用TiO 2 -Cr 2 O 3 氧化物的钙热共还原直接合成TiCr 2 金属间化合物粉末的新工艺路线。差热分析 (DTA) 和 X 射线衍射 (XRD) 用于确定各种反应。根据 DTA 结果,将混合物加热至约 675 °C 导致吸热峰。该吸热峰表明通过TiO 2 与Cr 2 O 3 的反应形成了固溶体。随着温度升高至约 950 °C,Ca 开始熔化(在约 847 °C 时),由于 Ca 与 Cr 2 O 3 反应形成 Cr 金属而导致放热峰。CaO与TiO 2 反应形成的CaTiO 3 的形成降低了起始材料混合物中TiO 2 的量。当混合物加热到 1058°C 时,如形成Ti的放热反应所示,Ca与TiO 2 反应形成Ti。最后,当1200℃保温时间和Ca含量增加时,形成TiCr 2 金属间化合物,同时CaTiO 3 化合物逐渐分解为CaO和Ti,样品中氧含量降低。得到的金属间化合物粉末经活化后显示出储氢能力。
The investigation of the Zr1−yTiy(Cr1−xNix)2–H2 system 0.0≤y≤1.0 and 0.0≤x≤1.0 Phase composition analysis and thermodynamic properties
作者:M Bououdina、H Enoki、E Akiba
DOI:10.1016/s0925-8388(98)00792-0
日期:1998.12
The Zr1-yTiy(Cr1-xNix)(2) compounds were synthesized and characterized by means of X-ray powder diffraction. From the Rietveld analysis carried out on the alloys, we determined the phase abundancy and refined the crystal structure. The system crystallized with hexagonal C14-type structure for nickel content less than x = 1.0 with some amount of additional phases (ZrNi, Zr9Ni11, Zr7Ni10, TiNi) and pure metals (Ni and Cr). For higher nickel concentrations, the system crystallized in the cubic C15-type structure. The amount of additional phases increased with increasing nickel and titanium content. The Pressure-Composition-Temperature measurements using a volumetric method were carried out at 313 K on some selected alloys. The single phase systems were found to absorb a large amount of hydrogen (H/M less than or equal to 1.8 wt.%) but had very poor kinetics. The multiphase systems were found to behave as a single phase (presence of single plateau), have a relatively good hydrogen capacity (H/M less than or equal to 1.4 wt.%) and exhibit faster kinetics. A Linear correlation between the heat of formation of the Zr1-yTiy(Cr1-xNix)(2) hydrides estimated from the band structure model and the unit cell volume of the alloys determined from the X-ray Rietveld analysis was obtained. It shows a decrease of hydride stability with increasing unit cell volume. (C) 1998 Published by Elsevier Science S.A. All rights reserved.
查看更多