材料期刊网

腐蚀保护层中六价铬含量分析

林子丰 , Roland Vogel , Claudia Andrle

电镀与涂饰

六价铬是一种致癌物质,它在汽车和电子工业中的应用受到欧盟的严格限制.目前,在腐蚀保护层中测定Cr(Ⅵ)的分析方法已经颁布实施.本文介绍了可用于上述两个行业的Cr(Ⅵ)检测标准--EN 15205和IEC 62321,并讨论了两者的差别.

关键词: 钝化膜 , 六价铬 , 检测 , 标准

Monte Carlo simulation on dielectric relaxation and dipole cluster state in relaxor ferroelectrics

Chinese Physics B

The Ginzburg-Landau theory on ferroelectrics with random field induced by dipole defects is studied by using Monte Carlo simulation, in order to investigate the dipole configuration and the dielectric relaxation of relaxor ferroelectrics. With the increase of random field, the dipole configuration evolves from the long-range ferroelectric order into the coexistence of short-range dipole-clusters and less polarized matrix. The dipole-cluster phase above the transition temperature and superparaelectric fluctuations far below this temperature are identified for the relaxor ferroelectrics. We investigate the frequency dispersion and the time-domain spectrum of the dielectric relaxation, demonstrating the Vogel-Fulcher relationship and the multi-peaked time-domain distribution of the dielectric relaxation.

关键词: relaxor ferroelectrics;domain structure;relaxation spectrum;Ginzburg-Landau theory;phase-transition;domain formation;random-field;thin-films;behavior;model;permittivity;polarization;perovskites;defects

Application of a probability model for relaxation to the dielectric alpha- and beta-relaxation of amorphous polyethylene terephthalate

Journal of Physics-Condensed Matter

A probability model (PM) developed recently, which is an alternative to the conventional Havriliak-Negami (HN) dispersion function for polymer systems, is applied for the first time to the study of the dielectric alpha- and beta-relaxation of amorphous polyethylene terephthalate (PET). It has been found that the temperature dependence of the maxima of the imaginary part of the dielectric function and of the half-width of the distribution in the PM of the alpha-relaxation exhibit Vogel-Fulcher-type temperature behaviour; the temperature dependence of the maxima of the imaginary part of the dielectric function of the beta ation is proportional to the ratio of the gauche content to the trans content of the ethylene glycol linkages in PET. Finally, the mechanisms of the alpha- and beta-relaxation are elucidated concisely.

关键词: kohlrausch-williams-watts;domain havriliak-negami

Superparamagnetic behaviour in melt-spun Ni2FeAl ribbons

Journal of Physics-Condensed Matter

Heusler alloy Ni2FeAl has been synthesized by the melt-spinning technique. The dc magnetization and frequency-dependent ac susceptibility measurements reveal that this alloy exhibits the characteristic feature of superparamagnetism. This behaviour may be associated with a structural disorder stemming from the fast quenching after the heat treatment. The small frequency-dependent ac susceptibility shifts in the blocking temperature and the existence of a pronounced peak in FC magnetization as well as Vogel - Fulcher activation processes indicate that intergranular interactions dominate in the melt-spun ribbons of Ni2FeAl.

关键词: magnetic-properties;spin-glass;heusler alloys;particles;films;ferromagnetism;transformation;model

Al88Ni4Y6Er2非晶合金动力学性能

牛犇 , 王丽娜 , 王海霞 , 陈东明 , 李荣娟 , 孙民华

稀有金属 doi:10.3969/j.issn.0258-7076.2009.04.010

采用单辊旋淬法制备了Al88Ni4Y6Er2非晶合金,用X射线衍射(XRD)、差示扫描量热(DSC)测试手段研究了Al88Ni4Y6Er2非晶合金晶化过程中的动力学性能.发现Al88Ni4Y6Er2非晶合金晶化温度Tx与升温速率φ通过Vogel-Fulcher-Tammnann公式拟合后满足非线性关系.并根据Tx10≈Tk这种近似关系,求得Al88Ni4Y6Er2非晶合金的Kauzmann温度Tk为401 K,由此推断出VFT温度T0不大于401 K.

关键词: 铝基非晶合金 , 晶化激活能 , 非线性关系

金属玻璃的粘度及粘滞性流变激活能

高逸群 , 郑福前 , 刘雄 , 廖宗尧

金属学报

用蠕变法测量了PdCu_6Si_(16.5),PdNi_6Si_(16.5)和CuZr_(43)三种金属玻璃在玻璃转变温度附近的粘度-温度依赖关系。在Newtonian粘度范围内,三种玻璃的粘度-温度依赖关系均可用Fulcher-Vogel方程进行描述。方程中的常数由实验曲线所确定,并由此计算出这些玻璃的粘滞性流变的表观激活能。同时用差热分析测定了金属玻璃PdNi_6Si_(16.5)和CuZr_(43)的热转变激活能。结果发现,PdNi_6Si_(16.5)合金的粘滞性流变激活能同热转变激活能的差别很小,而CuZr_(43)合金的差别则比较大。

关键词:

Pt_(69.0)Ni_(9.6)P_(21.4)合金的比热和Kauzmann温度

蒋青 , 徐晓亚 , 李建忱

金属学报

通过测量Pt69.9Ni9.6P21.4合金晶体和液体的比热函数和相应的嫡函数，确定了该合金的Kauzmann温度和反Kauzmann温度确定的Kauzmann温度与根据Vogel－Fulcher定律以及根据合金熔点计算的结果一致在测量中，通过采用不同加热速度加热玻璃的方法扩大了过冷液体在玻璃转变温度附近比热的温度测量范围，由此增加了过冷液体的热力学函数的可靠性此外，研究了在晶体样品表面形成氧化膜使晶体过热的可能性。

关键词: Pt_(69.0)Ni_(9.6)P_(21.4)合金 , specific heat , Kauzmann temperature

BaZr0.35Ti0.65O3陶瓷的弛豫特性及可调性

江福兰 , 李龙珠 ,

人工晶体学报

采用固相法制备了BaZr0.35Ti0.65O3(BZT35)陶瓷.研究了它的弛豫性相变.样品在100 Hz～100 kHz下的介电温谱显示宽化的介电峰值温度,随着频率的增加向高温方向移动,表明了该样品的弛豫特性.弛豫指数(γ)和峰宽化参数(△)可以通过对居里-外斯定律的进行线性拟合得到,1 kHz频率下,γ=1.91,△=44.9 K,表明样品具有很强的弛豫特性.利用Vogel-Fulcher公式对数据拟合进一步证实了样品的弛豫特性.研究表明,BZT35陶瓷具有巨大的可调性,可应用于可调电容器.

关键词: BaZr0.35Ti0.65O3陶瓷 , 介电性能 , 弛豫性相变 , 可调性

Effect of Ni on the formation and thermal behavior of NdAlCo metallic glasses

Yanxin ZHUANG

金属学报(英文版)

Nd₆₀Al{₁₀Co_30-xNi_x (x=0, 5, 10 and 15 at. pct) metallic glasses have been prepared using single-spinner and suck-casting method, and characterized using X-ray diffraction (XRD) and non-isothermal differential scanning calorimetric technique. It has been found that the alloy with 15 at. pct Ni has the strongest glass forming ability, and can be fabricated to a rod with 5 mm in diameter using suck-casting. The addition of Ni has an obvious effect on the thermal behavior of the metallic glasses, especially on the position of the second and third crystallization peaks. The crystallization kinetics and activation energies of the four metallic glasses have been elaborated using the Kissinger equation. The continuous heating transformation curves of the T_x and T_p1 have been constructed by applying the extension of the Vogel-Fulcher-Tammann (VFT) nonlinear equations, which are derived from the experimental data in the heating rate range of 5--80~K/min. The effect of Ni on the formation and thermal stability of the Nd-based metallic glasses has been discussed.

关键词: Nd-based metallic glass

层状双金属氢氧化物复合改性聚偏氟乙烯凝胶电解质研究

丛林凤 , 包永忠 , 黄志明 , 翁志学

材料科学与工程学报 doi:10.3969/j.issn.1673-2812.2006.02.014

采用共沉淀法制备了十二烷基硫酸根插层的层状双金属氢氧化物(DS-LDH),并与聚偏氟乙烯(PVDF)基质子交换和锂离子传导凝胶电解质复合.研究了DS-LDH在PVDF凝胶电解质中的分散及其对电导率的影响.发现DS-LDH基本以剥离、纳米尺度分散在PVDF电解质中.质子交换和锂离子传导电解质膜的电导率均随DS-LDH含量的增加先增加,当DS-LDH质量分率分别为7.4%和5.66%(基于PVDF质量)时,电导率达到最大值.未改性和复合PVDF基锂离子电解质的电导率均随温度的增加而增加,并都符合Vogel-Tamman-Fulcher方程.

关键词: 聚偏氟乙烯 , 层状双金属氢氧化物 , 复合 , 凝胶电解质 , 电导率