Květa Jirátová
,
Alla Spojakina
,
Luděk Kalu?a
,
Radostina Palcheva
,
Jana Balabánová
,
Georgi Tyuliev
催化学报
doi:10.1016/S1872-2067(15)61016-6
将Al和/或Ce的硝酸盐与NH4HCO3球磨混合，采用机械化学法制备了Al2O3-CeO2载体(其中Ce含量为1–10 wt%)，再以杂多钼酸盐(NH4)4NiMo6O24为活性金属Ni和Mo的前驱体，通过浸渍法制备NiMo6/Al2O3-CeO2催化剂，并将其用于1-苯并噻吩(BT)的加氢脱硫(HDS)反应中.运用化学分析、X射线衍射、N2吸附-脱附法、H2程序升温还原、NH3程序升温脱附和X射线光电子能谱对催化剂的物化性质进行了表征.结果表明，催化剂的酸性随着载体中Ce含量的增加而下降. Ce修饰的Al2O3载体表面的NiS/MoS原子比下降了2倍. NiMo6/Al2O3催化剂表现出最高的HDS活性(以单位重量催化剂计)，其酸性和表面MoOxSy物种的浓度(Mo5+浓度)也最高；当催化剂中Ce含量逐渐增加到10 wt%以上时，其活性逐渐将为0.与浸渍法制得的参比催化剂相比，前驱体和催化剂组成相同的情况下，采用机械化学法制得的所有催化剂活性明显提高.
关键词:
镍
,
钼
,
氧化铝
,
氧化铈
,
Anderson型杂多钼酸盐
,
1-苯并噻吩
,
加氢脱硫
,
机械化学法
沈军
,
马学著
,
贾均
中国稀土学报
在TiAl合金中加入以Ce和La为主要元素的混合稀土得到普通铸态和熔体旋淬法试样. 稀土元素以金属间化合物AlCe(AlLa)分别存在于晶粒边界和层片结构之上. 本文基于对二元合金平衡相图的分析以及应用Miedema生成热模型对稀土相AlCe(AlLa)的形成进行了分析. 结果表明, Al元素与Ce和La的亲和力远大于其与Ti之间的亲和力, 因此, TiAl基合金中的富稀土相以AlCe(或AlLa)的形式存在, 是必然的结果.
关键词:
稀土
,
TiAl合金
,
稀土相
,
形成热
陈长军
,
王茂才
,
王东生
,
金人
,
刘一鸣
材料科学与工艺
doi:10.3969/j.issn.1005-0299.2007.06.022
为了研究纯稀土对镁合金腐蚀性能的影响,用高能微弧火花合金化(电火花)设备在ZM5镁合金上进行了La合金化.使用金相、电子探针和X射线衍射仪等设备对获得的涂层进行了显微结构和成分分析.并利用电化学测试仪器进行了极化曲线的测试.研究表明,可获得无气孔、裂纹的冶金结合的界面和合金化层,成分分布存在一个渐变的过程.合金化层主要由稀土镧、AlLa2与Mg17Al12相组成;合金化层的腐蚀电位正移了大约59 mV,而合金化层在3.5%NaCl溶液中的耐腐蚀性能几乎没有改善.
关键词:
镁合金
,
镧
,
电火花合金化
,
腐蚀
H. Ying1)
,
X. D. Sun1)
,
Q. B. Yang1)
,
J. B. Li2)
,
Y. M. Wang2)
,
Z. Zhang3) and J. You3)1) School of Materials and Metallurgy
,
Northeastern University
,
Shenyang 110006
,
China2) Departm ent of Materials
,
School of Mechanical Engineering
,
Shenyang University
,
Shenyang110044
,
China3) Liaoning Analyzing and Testing Research Center
,
Shenyang 110015
,
China
金属学报(英文版)
Starting from cheap inorganic salts , ultrafine P L Z T po w ders were synthesized by a co pre cipitation m ethod . The results show that the precursor precipitate obtained by the co precipita tion method transfor ms co m pletely to P L Z T phase by calcining at 420 ℃ for 4 hours , about300 ℃low er than the nor m al transform ation te m perature of P L Z T obtained by m ixed oxidemethod . The effect of residual N H4 N O3 in the precursor precipitate on transfor m ation te m perature of the P L Z Tpow der w as investigated . The residual N H4 N O3 in the precursor po w der can reduce further the P L Z Ttransfor m ation tem perature to about 300 ℃, but a sm alla mount of Zr O2 and Pb Ti O3 re m ained . By a proper control of the synthesizing route , a P L Z T po w der with a pri m ary particle size of 10 n m and an agglom eration size of 0 3 μm hasbeen produced .
关键词:
P L Z T
,
null
,
null
Oxidation of Metals
Al-La thermal diffusing was conducted on Ti3SiC2-base ceramic by the pack-cementation method. The microstructure, phase and oxidation resistance of the diffusion layer were characterized. The complete aluminide coatings have not been obtained. Al and La penetrated into the Ti3SiC2 substrate quickly, distributing into the whole interior of the specimen after cementation at 1100degrees C for 4 hr. Al existed as a solid solution and dispersed particles of AlLa3. Oxidation of cemented Ti3SiC2 at 1100degrees C in air for 20 hr formed a single continuous Al2O3 layer with a small amount of TiO2 grains on the outer layer. Compared with Ti3SiC2, the parabolic rate constant of the cemented Ti3SiC2 was decreased by two orders of magnitude, which means that the cementation treatment remarkably improves the oxidation resistance of Ti3SiC2. Al distributed in Ti3SiC2 acted as "a reservoir'' to supply enough Al for the formation of a continuous Al2O3 scale during the oxidation process.
关键词:
Titanium-silicon carbide;Al-La cocementation;oxidation;oxide scale;air
崔大伟
机械工程材料
为了提高镧-镁-镍贮氢合金电极的性能,向该合金粉体中掺加少量的铝粉,并用放电等离子烧结技术制备了La_(0.7)Mg_(0.3)Ni_(2.5-x)Co0.5Al_x(x=0～0.3)合金,用X射线衍射仪、扫描电镜和电化学测试系统等研究了该合金的组织和相应的性能.结果表明:制备的合金为多相结构,主相均为六方Ce_2Ni_7型的(La,Mg)_2Ni_7相和菱方PuNi_3型的(La,Mg)Ni_3相,另外还有少量的Mg_2Ni相或AlCo相和AlLa_3相;合金的最大放电容量在x=0时达到最大值359.0 mAh/g,随x值的增大,放电容量逐渐减小,当x=0.3时降低到294.8 mAh/g;合金均具有良好的活化性能(初始活化次数为1～2次);元素铝的加入对合金循环稳定性的作用不明显,但降低了合金的放电平台电压和放氢压力,降低幅度约为2.5%.
关键词:
贮氢合金
,
放电等离子烧结
,
电极性能
