导电聚苯胺的合成及电磁学性能、吸波性能研究

分别采用溶液聚合、乳液聚合、正相和反相微乳液聚合法合成了不同掺杂、不同电导率(电导率范围10-5～10S/cm)的聚苯胺,测试了导电聚苯胺的电磁学参数和吸波性能。结果证明制得的聚苯胺在2～12GHz范围内有较好的吸波性能,在2～12GHz范围内,雷达波反射率绝对值大于10dB的频宽范围大于7.5GHz,最大吸收率达到30dB。

镍-二硫代乙烯类配合物R_n[Ni(bbdt)_2]的电磁学性能研究

在合成Rn[Ni(bbdt) 2 ]系列配合物的基础上 ,通过EPR谱、XPS谱、变温磁化率和室温电导率的测定 ,研究了配合物的电磁学性能 .结果表明 ,在Rn[Ni(bbdt) 2 ](n =0 ,0 .5 ,1,2 )系列配合物中 ,n =0 ,0 .5 ,1对应的配合物室温EPR谱中有特征的单电子信号 ;XPS测定的结合能数据说明 ,中心Ni离子对阴离子部分的荷电量不敏感 ,而配体S原子的结合能随荷电量有较大变化 ;n =0 ,0 .5对应的配合物表现出较好的电磁学性能 .

手性聚苯胺的制备及其电磁学性能研究

采用二次掺杂法制备了具有手征特性的聚苯胺,利用傅立叶红外光谱(FT-IR)、X射线衍射仪(XRD)、圆二色谱仪(CD)和紫外-可见光分光光度计(UV-vis)等分析手段对聚苯胺的结构、性能和手征特性进行了表征。结果表明,通过过硫酸铵作引发剂、盐酸掺杂获得了导电的盐酸掺杂态聚苯胺(PANI-HCl);通过氨水脱掺杂后得到本征态聚苯胺(EB),EB通过手性樟脑磺酸(CSA)诱导,形成了手征性螺旋构型聚苯胺。电磁性能测试表明,与非手性聚苯胺相比,手性聚苯胺具有较优越的吸波性能。

贵金属纳米粒子/无机复合材料的制备及性能

介绍了贵金属纳米粒子 /无机复合材料的制备方法 ,陈述了这类材料在光、电、磁、催化等方面的性能 。

共沉淀法制备多铁性体BiMn_2O_5及其性能表征

采用共沉淀法合成制备了多铁性体BiMn2O5,对其进行了物相分析和形貌表征,表征分析了它的磁学和电学性能,并系统描述了BiMn2O5的磁结构。实验表明：在pH=11的共沉淀条件下制备的前驱体微粉,经800℃焙烧后可得到纯相的BiMn2O5粉体,其颗粒分布均匀、形貌完整且粒径在100nm左右。文章测量得到BiMn2O5在室温下1MHz时介电常数εr=41.6和介电损耗tanδ=0.336,并通过SQUID检测其磁相转变温度为42K（TN=39~42K）,得出有效磁矩μeff=6.72μB,在5K时测得BiMn2O5的磁滞回线,显示其矫顽力高达6000Oe,与之前研究相比有很大提升。

纳米材料结构与性能的计算机模拟研究

先进的理论和计算技术结合计算机的威力,提供了在原于层次上了解纳米材料及其演化过程细节的可能性,兵有无先例的准确性,使纳米材料设计和性能预测成为可能。本文首先概述了计算机模拟的理论方法和作用,扼要地综述了计算机模拟在纳米材料的微观结构、力学、热学、电磁学等性能的研究进展,最后阐述了纳米材料结构和性能的计算机模拟研究所面临的问题。

一种多场环境下超导材料力学性能的测试装置

超导材料作为一种新型智能材料,在能源、交通、电力以及科学实验等诸多领域都得到了广泛的应用。超导材料往往处于多场环境下,其在多场耦合环境下的力学、热学和电磁学性能的表征成了人们研究的热点。本文设计了一种测试装置,模拟了真空、低温、磁场、电场等多种环境,在此环境下测试超导材料的各种力学性能,具有简单易操作,模拟程度高,实验结果可靠等特点。

Structural and optoelectronic properties of AZO thin films prepared by RF magnetron sputtering at room temperature

Al-doped ZnO thin films were prepared on glass substrate using an ultra-high density target by RF magnetron sputtering at room temperature. The microstructure, surface morphology, optical and electrical properties of AZO thin films were investigated by X-ray diffractometer, scanning electron microscope, UV-visible spectrophotometer, four-point probe method, and Hall-effect measurement system. The results showed that all the films obtained were polycrystalline with a hexagonal structure and average optical transmittance of AZO thin films was over 85 % at different sputtering powers. The sputtering power had a great effect on optoelectronic properties of the AZO thin films, especially on the resistivity. The lowest resistivity of 4.5×10^-4 Ω·cm combined with the transmittance of 87.1% was obtained at sputtering power of 200 W. The optical band gap varied between 3.48 and 3.68 eV.

Effects of Fe_(2)O_(3) content on microstructure and mechanical properties of CaO-Al_(2)O_(3)-SiO_(2) system

The effects of Fe2O3 content on the microstructure and mechanical properties of the CaO-Al2O3-SiO2 system were investigated by differential thermal analysis（DTA）, X-ray diffraction（XRD）, scanning electron microscopy（SEM）, electron spin resonance（ESR）, and Mssbauer spectroscopy. The results show that the addition of Fe2O3 does not affect the main crystalline phase in the prepared glasses, but it reduces the crystallisation peak temperature, increases the crystallisation activation energy, and reduces the crystal granularity. The ESR results indicate that Fe2O3 can promote crystallization, as it leads to the phase separation of the CaO-Al2O3-SiO2 system due to axial distortion. Moreover, Fe2O3 alters the network structure of the CaO-Al2O3-SiO2 system, allowing Fe3＋ to enter octahedral sites that exhibit higher symmetry than tetrahedral sites. All of these factors are favourable to increasing the bending strength. The Mssbauer results reveal that there are two types of coordination for both Fe3＋ and Fe2＋ and the bending strength of the CaO-Al2O3-SiO2 system increases with the amount of six-coordinate Fe3＋. The increasing interaction between Fe3＋ and Fe2＋ can also enhance the bending strength of the CaO-Al2O3-SiO2 system. The microhardness of the CaO-Al2O3-SiO2 system was determined to be HV 896.9 and the bending strength to be 217 MPa under the heat treatment conditions of nucleation temperature of 700 °C and nucleation time of 2 h, crystallization temperature of 910 °C and crystallization time of 3 h.

钨／钼酸盐体系红色荧光粉成研发热点

白光发光二极管是一种新型照明器件，具有节能、环保、寿命长、体积小、响应快、封装方便等许多优点，发展非常迅速。红色荧光粉是白光发光二极管照明应用中的一种关键发光材料，对提高白光发光二极管的光色纯度、降低色温等有决定性作用，其研发至关重要。钨／钼酸盐红色荧光粉具有优良的发光性能、电磁学性能、化学稳定性及应用性，

Effect of pulsed electromagnetic frequency on the microstructure, wear and solid erosion resistance of CrAlN coatings deposited by arc ion plating

In this work,the chromium aluminum nitride(CrAlN)coatings were prepared on TC11 titanium alloy by composite magnetic field cathodic arc ion plating with controllable pulse electromagnetic combined with permanent magnet.The effects of electromagnetic frequency on the morphology,microstructure,nano-hardness and elastic modulus of the coatings were investigated by scanning electron microscope(SEM),X-ray diffraction(XRD)and nano-indenter.This paper has mainly studied the influence of CrAlN coatings which are prepared at various electromagnetic frequencies on the wear and erosion resistance through a series of wear and solid particle erosion experiments.It was found that the deposition rate of CrAlN coatings increases with the increase of electromagnetic frequency.And CrAlN coatings all preferentially grew along the(111)crystal plane.At 16.7 Hz,with the increase of pulsed electromagnetic frequency,the hardness is the highest(23.6 GPa)and the adhesion is the highest(41.5 N).In addition,the coating deposition exhibited the best wear and solid erosion resistance at 16.7 Hz and 33.3 Hz,the friction coefficient is about 0.35,and the erosion rate is about 0.2μm/g at 30°and less than 1μm/g at 90°,respectively.These results indicate that the CrAlN coating formed at an appropriate pulsed electromagnetic frequency can achieve excellent mechanical properties,wear and solid erosion resistance.

Effects of electromagnetic vibration on the structure and mechanical properties of Al-6%Si alloy during directional solidification

The effects of electromagnetic vibration on the grain refinement in directional solid- ification were investigated. It was found that the electromagnetic vibration applied in the melt not only can refine grains remarkably but also can enhance both tensile strength and ductility values of Al-6%Si alloy. SEM graphs show that coarse dendrite structure was broken up into a somewhat globular structure, and the morphology of eutectic silicon was changed from flaky to fibrous under electromagnetic vibration treatment. The refine mechanism under electromagnetic vibration was discussed.

Effects of electromagnetic stirring on microstructure and mechanical properties of super light Mg-Li-Al-Zn alloy

Effects of electromagnetic stirring on the microstructure and mechanical properties of the magnesium-lithium-aluminum alloy were studied.The results reveal that,the morphology of theαphase changes from the long block to globular structure andβ phase distributes more widely in the periphery ofαphase when the electromagnetic stirring voltage is higher than 110 V.The mechanical properties are increased significantly with the increasing electromagnetic stirring.The tensile strength is improved from 172 to 195 MPa,and the elongation is increased from 10.65%to 25.75%.

Optical properties and magnetic properties of antisite-disordered Ni_(1-x)Co_xCr_2O_4 spinels

From the UV?Vis absorption spectra,the FT-IR absorption spectra and the Raman spectra,it is deduced that Co ionsprimarily occupy the tetrahedral(A)site,with a minor number of them entering into the octahedral(B)site in the Ni1?xCoxCr2O4compounds.The origin of the position disorder of the Co ions is consistent with the similar ionic radii of the Co ion(0.65?)and theCr ion(0.62?)at B site.The FT-IR peak at about510cm?1shifts towards high frequency side with the increasing cobalt content.Itis resulted from the reduction of the cation?oxygen distance in the octahedron by the replacement of the Ni2+with the Co2+ions.Themagnetic measurement shows that Curie temperatures(TC)are75and90K for the compounds with x=0.2and0.8,respectively.

Influence of Ni^(2+)/Co^(2+)ratio in electrolyte on morphology,structure and magnetic properties of electrolytically produced Ni-Co alloy powders

Nickel-cobalt(Ni-Co) alloy powders were produced galvanostatically by using sulphate electrolytes with various ratios of Ni2+/Co2+(mole ratios). The morphology, phase structure, chemical composition and magnetic properties were examined by scanning electron microscope(SEM), X-ray diffractometer(XRD), atomic emission spectrometer(AES), and SQUID-based magnetometer, respectively. Morphology of the particles changed from cauliflower-like and dendritic to coral-like and spongy-like ones with increasing Ni2+/Co2+ ratio from 0.25 to 4.0. XRD analysis of the Ni-Co powders revealed that the decrease of Ni2+/Co2+ ratios(the increase of Co content) caused a change of structure from face centered cubic(FCC) obtained for the ratios of 4.0, 1.5 and 0.67 to a mixture of FCC and hexagonal closed-packed(HCP) phases for the ratio of 0.25. The increasing content of nickel led to change of mechanism of electrolysis from irregular(up to 40 wt.% Ni in the electrolytes) to close to equilibrium(between 40 and 60 wt.% Ni in the electrolytes) and anomalous co-deposition(over 60 wt.% Ni in the electrolytes) type. All of the obtained Ni-Co alloy samples behaved as soft magnetic materials while their magnetic parameters showed immediate composition dependence since both coercivity and saturation magnetization almost linearly increased with increase of the Co content.

Direct-chilling casting of Mg alloy under electromagnetic and ultrasonic combined field

The effects of low frequency electromagnetic (LFEC) field and ultrasonic (US) field on the microstructures, macrosegregation of alloying elements and the mechanical properties of DC cast AZ80 alloy were studied. The results show that both LFEC and US fields can refine the grains of the billets, which results in the increase in mechanical properties and uniformity of alloying element distribution. The effective refinement takes place on the edge of ingots when LFEC field is applied, while in the center of billets when field US is adopted. Combined the characteristics of LFEC and US fields, a new process for direct-chilling (DC) casting of Mg-electromagnetic-ultrasonic (ECUS) casting is developed, by which the grains are refined significantly and are more uniform in the whole ingots, and the mechanical properties of the ingots are improved.

Optimization of mechanical properties using D-optimal factorial design of experiment: Electromagnetic stir casting process of A357-SiC nanocomposite

Electromagnetic stir casting process of A357-Si C nanocomposite was discussed using the D-optimal design of experiment(DODOE) method. As the main objective, nine random experiments obtained by DX-7 software were performed. By this method, A357-Si C nanocomposites with 0.5, 1.0 and 1.5 wt.% Si C were fabricated at three different frequencies(10, 35 and 60 Hz) in the experimental stage. The microstructural evolution was characterized by scanning electron and optical microscopes, and the mechanical properties were investigated using hardness and roomtemperature uniaxial tensile tests. The results showed that the homogeneous distribution of Si C nanoparticles leads to the microstructure evolution from dendritic to non-dendritic form and a reduction of size by 73.9%. Additionally, based on DODOE, F-values of 44.80 and 179.64 were achieved for yield stress(YS) and ultimate tensile strength(UTS), respectively, implying that the model is significant and the variables(Si C fraction and stirring frequency) were appropriately selected. The optimum values of the Si C fraction and stirring frequency were found to be 1.5 wt.% and 60 Hz, respectively. In this case, YS and UTS for A357-Si C nanocomposites were obtained to be 120 and 188 MPa(57.7% and 57.9 % increase compared with those of the as-cast sample), respectively.

不锈钢一般物理性能

和其他材料一样，物理性能主要包括以下3个方面：熔点、比热容、导热系数和线膨胀系数等热力学性能，电阻率、电导率和磁导率等电磁学性能，以及杨氏弹性模量、刚性系数等力学性能。这些性能一般都被认为是不锈钢材料的固有特性，但是也会受到诸如温度、加工程度和磁场强度等的影响。通常情况下不锈钢与纯铁相比导热系数低、电阻大，而线膨胀系数和导磁率等性能则依不锈钢本身的结晶结构而异。

Performance calculation and improved model research of direct-drive permanent magnet generator based on FEM

In some control strategies of the direct-rive permanent magnet generator(DDPMG),the mathematics model is excessively simplified and some complex nonlinear characteristics,such as core saturation and cross-saturation,are generally neglected.To solve this problem,this paper utilizes the frozen element permeability method to compute the armature self-and mutual-inductance,permanent magnet d-and q-axis flux varying with d-axis and q-axis current,then an improved model is presented in which the core saturation and cross-saturation between d-axis and q-axis are considered effectively.Based on this model,the method for computing the performance of the generators is also proposed.Taking a 1.5-MW DDPMG as an example,the time-stepping finite element method(T-S FEM) is adopted to analyze the performance with no-load and loaded conditions,the results show a good agreement with the ones obtained by the improved model.Compared with the simplified model,it is demonstrated that the presented model has the high efficiency and reliability and can provide a good reference for optimization design of DDPMG and other PM motors.

Analysis on the process of ZAO films by DC magnetron reactive sputtering

The ZAO (ZnO:Al) thin films were prepared by DC reactive magnetron sputtering technique. The relationship between the process parameters and the organizational structure,optical and electrical properties was studied. Through optimizing the process parameters,an optimal preparation parameter can be obtained. Using the optimal parameters to prepare the ZAO thin films,the resistivity of the ZAO film is as low as 4.5×10-4 Ω·cm and the average transmissivity in the visible region is around 80%,the optical and electrical properties meet the application requirements.