Si-Young Sung
,
Bong-Jae Choi
,
Beom-Suck Han
,
Han-Jun Oh
,
Young-Jig Kim
材料科学技术（英文）
The alpha-case formation reactions between Ti and investment molds (Al2O3, ZrSiO4, ZrO2, CaO stabilized ZrO2) were evaluated in a plasma arc melting furnace. Regardless of thermodynamic approaches, there were distinct alpha-case formations. The reaction products were characterized by electron probe micro-analysis and transmission electron microscopy. The α-case generation between Ti and Al2O3 mold was not able to be explained by the conventional α-case formation mechanism, which is known to be formed by the interstitials, especially oxygen dissolved from mold materials. However, from our experimental results and thermodynamic calculations, it was confirmed that the α-case is formed not only by an interstitial element but also by substitutional metallic elements dissolved from mold materials. Our newly established α-case formation mechanism will surely lead to a variety of significant applications of the α-case controlled Ti casting.
关键词:
Titanium
,
null
,
null
,
null
赫文秀
,
安胜利
,
张永强
,
孙海峰
,
杨慧
,
蒋文全
中国稀土学报
化学共沉淀法合成氢氧化镍,并在表面用"梯度共晶法"复合包覆Co(OH)x+Yb(OH)3.XRD,XPS,SEM表征结果表明:制备的样品为六方球形β-Ni(OH)2,表面包覆了Co(OH)x+Yb(OH)3,Co的存在形式应该主要为Co2+及少量的Co3+.65℃下0.2C,1C和3c恒电流充放电时,复合包覆Co(OH)x+2%Yb(OH)3的氢氧化镍的放电比容量和放电效率最大.大倍率充放电和循环稳定性等性能也得到改善.
关键词:
包覆
,
放电容量
,
循环性能
,
Yb(OH)3
,
稀土
By ZHANG Yi WANG Yingxia HUA Tongwen Institute of Chemical Metallurgy
,
Academia Sinica
,
Beijing
,
100080
,
China.Department of Chemistry
,
Peking University
,
Beijing
,
100871
,
China.To whom correspondence should be addressed.
材料科学技术（英文）
The kinetics of α-FeO(OH) formation in weak acidic medium was studied.The effects of the initial concentration,temperature,pH value,partial pres- sure of oxygen,air flow rate and agitating intensity on the oxidation rate of Fe(OH)_2 suspensions have been investigated.It is confirmed that the reaction order for Fe(Ⅱ) is zero at the stage of α-FeO(OH) seeds formation,and about 0.5 at the stage of the seeds growth,and in the whole process partial pres- sure of oxygen appears in first order.The activation energy is determined.The dissolution-oxidation equilibrium which exists in the process of seeds formation has been suggested,by which the zero order reaction for Fe(Ⅱ) and the plateau in the pH-t curve were explained.Physical process is the rate-determining step of the heterogeneous reaction.The study on the kinetics of α-FeO(OH) formation may provide some fundamental informa- tion for the reactor design,the engineering amplifi- cation and the optimization control in the industrial process.
关键词:
kinetics
,
null
,
null
,
null
杨书廷
,
陈改荣
,
尹艳红
,
陈红军
,
贾俊华
应用化学
doi:10.3969/j.issn.1000-0518.2001.09.003
采用均匀络合共沉淀法,首次合成出了掺杂钇基a-Ni(OH)2.并采用XRD,FTIR和SEM分析技术,对其结构及形貌进行了研究.电化学测试表明,所制得的掺杂钇基a-Ni(OH)2与掺铝的α-Ni(OH)2和球形β-Ni(OH)2相比,敲实密度1.6 g/cm2,电化学比容量330 mA@h/g以上,活性物质利用率大于95%,循环可逆性好等优点.
关键词:
a-Ni(OH)2,钇,掺杂,电化学性能
吴健松
,
肖应凯
,
张丽
,
匡文华
,
梁海群
,
吴康娣
应用化学
doi:10.3969/j.issn.1000-0518.2008.05.006
以MgCl2为原料,NaOH为沉淀剂,研究了它们的浓度配比、反应温度、晶化温度、晶化时间、晶化方式等因素对形成Mg(OH)2晶须的影响. 结果表明,当n(MgCl2): n(NaOH)=1.20: 1.92、混合温度Tm=86 ℃、晶化温度Tc=100 ℃、晶化时间Time=5.5 h时,可以得到发育不完全的初级Mg(OH)2晶须. 若改用水热法晶化,可得到发育较好的Mg(OH)2晶须. 在此基础上,若在NaOH溶液中加入一定量的有机溶剂OR(NaOH浓度不变)时,即可得到发育更完善的Mg(OH)2晶须. 电子显微镜照片显示,粒子呈晶须形状,粒度分布均匀,分散性好,晶形好,纯度高. 并对晶须生长机理进行了初步分析.
关键词:
Mg(OH)2
,
晶须
,
水热法
,
功能材料
胡劲
,
孙家林
,
刘建良
,
施安
,
徐茂
,
高勤琴
人工晶体学报
doi:10.3969/j.issn.1000-985X.2006.01.016
本文采用活化Al-Sr合金粉末水解反应制备Al(OH)3和Sr(OH)2复合粉末,利用XRD,SEM,EDS,BET及激光粒度仪对复合粉末进行结构和性能研究.研究结果表明,Al(OH)3和Sr(OH)2的复合粉末中Sr/Al比例与配比相比有所偏移,但在复合粉末中两者均匀混合,具有化学组成的微观均匀性.复合粉末微观形貌为1～3μm片状小颗粒叠加的团聚颗粒,BET比表面积较大,达到45.2m2/g,水解产物粒度分布均匀,D50为27.58μm,D25/D75为0.76.
关键词:
Al-Sr合金
,
水解
,
复合粉末
刘长久
,
叶乃清
,
刁汉明
应用化学
doi:10.3969/j.issn.1000-0518.2002.05.014
通过制备纳米级的β-Ni(OH)2粉体然后按一定比例掺杂Al(OH)3和Ni粉制成复合电极,研究其电化学性能. 实验结果表明,其电极结构稳定,活性增强. 开路电位达2.5 V,放电电位平稳,放电容量明显增大. 电极经3.0×10-3 A/cm2恒电流充电5 h后以0.7×10-3 A/cm2恒电流放电可达到16 h.
关键词:
β-Ni(OH)2,纳米粉体,Al(OH)3掺杂,电化学性能
