含添加物AgNi(10)线材的研究

研究了三种类型的添加物对AgNi(10)线材的加工性能及电性能的影响。在常规粉末冶金工艺的基础上，结合先进的高压水雾化合金粉末制备工艺，在AgNi(10)线材中分别进行了添加微量A、B、C、D、E、F等不同类型添加物的实验。根据线材机械物理性能实测数据，运用固溶强化、颗粒强化、弥散强化等理论，对比分析了不同类型添加物对AgNi(10)线材机械物理性能的影响机理。将含不同添加物的AgNi(10)线材分别加工成平面、球面复合铆钉型触头，并配对装配于ASTM标准试验机上进行电性能模拟试验，得出了含不同添加物的AgNi(10)线材的电磨损及接触电阻数据，并利用扫描电镜对电性能模拟试验后的触头表面形貌进行了对比观察，在此基础上初步分析了不同类型的添加物对AgNi(10)材料电性能的影响机理。     

Co_(38)Ni_(34)Al_(28-x)Si_x铁磁形状记忆合金的组织演变及磁性能

采用急冷快淬吸铸工艺制备Co38Ni34Al28-xSix(x=0,1,3,5,7,9)合金,利用光学显微镜、场发射扫描电镜(FE-SEM)和振动样品磁力计(VSM),研究了Si添加量对其显微组织、饱和磁化强度和居里温度的影响。研究表明,Si元素替代Al元素后,合金室温显微组织变化很大,添加量为x=1时,仍保持β基体不变,但γ相减少;添加量为3时,变为M+γ双相组织,添加量为5~9时,可获得单相马氏体组织。添加Si元素使合金的饱和磁化强度下降,当添加量为5和7时,饱和磁化强度的下降幅度最低。添加Si元素后,合金的居里温度有不同程度的提高,与添加量有关。     

John Petrucci的选择——Evidence Audio品牌The Lyric线材

线材在现代音乐产业里扮演着举足轻重的作用,无论是音乐的生产还是音乐的还原都仰仗于硬件设备的表现,相对于线材在整个信号流中所占投资的微小比例,其对音质的影响(无论是改善还是降低)却是巨大的.对于当今的线材世界,创立于1997年的Evidence Audio无疑是其中的翘楚.     

Zr添加对粘结钕铁硼磁粉结构和磁性能的影响

采用熔体快淬工艺制备了未添加Zr和添加Zr的两种复相纳米NdFeB磁粉。研究了Zr元素添加、晶化、磁化及研磨工艺对NdFeB磁粉微观组织结构及磁性能的影响。研究结果表明,Zr元素的添加可以有效抑制α-Fe晶粒的长大,从而达到细化晶粒、增强硬磁相和软磁相之间的交换耦合作用,提高磁粉磁性能的作用。含Zr钕铁硼磁粉最佳磁性能达Br=0.79 T,Hci=801 kA/m,(BH)max=98 kJ/m3。     

添加元素Co、Zr对NdFeCoAlB磁粉性能的影响

采用HDDR技术制备NdFeCoAlB各向异性磁粉,研究了添加元素Co、Zr对磁粉性能和磁各向异性的影响。结果表明,磁粉的剩磁(Br)随Co的增加而增加,添加少量Zr基本不改变Br;矫顽力(Hcj)随Co的增加而降低,随Zr的增加先提高后降低;各向异性均随Co、Zr的增加而增大。     

冷压焊工艺在AgNi(10)线材拉拔生产中的初步研究

现阶段AgNi(10)线材广泛用于20 A电流等级以下的继电器、控制器等用铆钉型触头及型材的加工,由于挤压工艺的限制,单捆AgNi(10)线材的重量无法有效提高,制约了线材生产的效率和成材率。本研究拟采用冷压焊工艺对AgNi(10)线材进行对焊接,研究焊接接口的金相组织和力学物理性能在不同对焊工艺及后续拉拔过程的变化情况,进而确定是否具有初步可行性。     

Al,Bi元素对合成LSCF的影响

将La(NO3)3、Sr(NO3)2、Fe(NO3)3和Co(NO3)2按照La0.8Sr0.2Co0.8Fe0.8O3(LSCF)摩尔比配置硝酸盐混合溶液,并在其中添加Al、Bi硝酸盐,用差示扫描量热法(DSC)、热重-差热分析法(TG-DTA)和X射线衍射光谱法(XRD)结合研究Al,Bi两种元素的添加对在锶掺杂的锰酸镧-氧化钇稳定的氧化锆(LSM-YSZ)阴极现场低温合成LSCF的影响。DSC、TG-DTA的研究结果表明,Al、Bi两种元素的加入,改变了LSCF前驱物的熔融状态和均匀性。XRD的研究结果表明,未添加和添加Al的样品,需要在800℃以上出现明显的LSCF钙钛矿结构特征峰,添加Bi的LSCF样品在650℃有明显的LSCF特征峰,Bi对LSCF钙钛矿结构形成有促进作用。添加Bi的LSCF样品有La稳定的Bi2O3和Sr稳定的Bi2O3峰。     

高温下Pb-Ca-Sn-Al-Re合金在硫酸溶液中的电化学性能研究

采用线性扫描(LSV)、交流阻抗(EIS)、循环伏安(CV)、金相实验等方法对比Pb-Ca-Sn-Al合金中添加稀土元素对合金高温条件下电化学性能的影响。实验结果表明,在合金元素中添加稀土在高温下能抑制氢气和氧气的析出,并能够促使合金表面生成更多的PbO和PbO_2氧化膜,这有利于铅酸蓄电池免维护性能的提高以及提升板栅的充放电性能。     

添加Ho对烧结Nd-Fe-B永磁材料磁性能与温度稳定性的影响

用常规工艺制备烧结( Pr-Nd )33.0-xHoxFebalCu0.20Al0.75B1.15(x=0,1,3,5)永磁材料.研究了Ho元素添加对材料磁性能和温度稳定性的影响.适量添加Ho有利于抑制合金铸锭中α-Fe的形成;制作的烧结磁体,其主相晶粒一定程度上细化、尺寸分布比较均匀;内禀矫顽力明显提高,剩磁有所下降...     

铝 空气电池铝合金阳极的研究进展

从铝活化-钝化机理、添加合金元素(镓、铟、镁、锡、锰、铋及铅等)对铝阳极性能的影响等方面,综述了铝-空气电池铝合金阳极的发展、研究及应用概况。     

一种改善三相不平衡下逆变器并网系统电能质量的新方法

针对典型的逆变器并网系统,研究三相不平衡度对公共并网点(PCC)电能质量的影响。三相不平衡电压经序分量分解后,由瞬时功率可推导其对并网逆变器直流侧二倍频波动量的影响,结合开关函数的傅里叶表达式,分析逆变器交直流侧交互影响机理,同时经过数学推导得出公共并网点的谐波特性。基于此谐波特性,建立由有源滤波器和无源滤波器组成的混合电力滤波器(HPF),达到改善并网电能质量的目的。利用Matlab/Simulink软件搭建三相不平衡并网系统,检测特定次谐波与理论推导值作对比,考虑并网系统具有的谐波特性,建立HPF滤波模块,验证了HPF在提高电网电压三相不平衡时并网系统的电能质量方面具有优越性。     

欧盟RoHS指令与电池指令解读

欧盟RoHS指令(关于电子电气设备中有害物质使用的限制)从2006年7月1日起开始实施。指令的主要内容有哪些?企业如何应对?怎样进行符合性评价?电池生产商还应执行哪些相关指令?上下游产品标准不一致时到底按哪个标准执行?根据中国电池工业协会7月5日北京会议精神,现对欧盟RoHS指令及与电池相关的环保指令作如下解读,并对其间的相互关系作了分析。     

Optimization of gallium-doped ZnO thin films grown using Grey–Taguchi technique

In this paper, optimization of the process parameters considering multiple performance characteristics to prepare the transparent conducting gallium-doped zinc oxide thin films with radio frequency (RF) magnetron sputtering was investigated. Experiments based on the Grey–Taguchi technique were conducted to examine the effect of deposition parameters including RF power, process pressure, substrates temperature and process time, aiming to obtain highly transparent and conductive films. Comparing with the optimal parameter set selected from orthogonal array by Taguchi method, the optimal grey theory prediction design (GTPD) can receive an improvement of 5.75?% in electrical resistivity and 1.47?% in optical transmittance. Further refinements respectively to RF power and process pressure with fixing other parameters level in GTPD were explored. The results show the alteration on RF power and process pressure in the GTPD can receive over 31?% and 51?% of improvement in electrical resistivity, respectively, with keeping the visible range optical transmittance over?85?%.     

Modeling of single-wall carbon nanotube interconnects for different process, temperature, and voltage conditions and investigating timing delay

The performance of Single-Wall Carbon Nanotube (SWCNT) based interconnect is investigated in this paper. CNT has become the most promising replacement for Cu based interconnects in future VLSI technologies in the nanometer regime. The process, temperature, and voltage (PTV) dependent equivalent circuit model for CNT based interconnect is developed. The performances of Cu and CNT based interconnects are compared for different ITRS technology nodes. The timing delay is analyzed in CNT based interconnect under different PTV conditions for 32?nm and 16?nm technology nodes. Process variation is modeled by considering the variations in CNT diameter, spacing, and metallic fraction. The delay variation is more than 100?% with process variation whereas with voltage and temperature the delay variations are ±20?% and ±50–60?% from the nominal voltage and room temperature, respectively. The diameter variation of CNT has almost no effect on the timing of SWCNT bundle based interconnects.     

Low-temperature dielectric properties of double-perovskite Ca2CoNbO6

Double-perovskite Ca₂CoNbO₆ (CCNO) ceramics were prepared via the solid-state reaction route. Their dielectric properties were investigated as a function of temperature (between 100 and 330?K) in the frequency range from 40?Hz to 10?MHz. Two thermally activated dielectric relaxations were observed with the activation energy around 0.13?eV for the low-temperature relaxation and 0.37?eV for the high-temperature relaxation. Annealing in O₂ and N₂ can remarkably change the dielectric constant, background, relaxation peak intensity and position, etc. These results can be well explained based on the fact that both oxygen and cobalt vacancies coexist in the sample. The low-temperature relaxation was found to be related to the dipolar effect due to the hopping holes, and the high-temperature relaxation was associated with the defect relaxation caused by oxygen and cobalt vacancies.     

Dielectric characteristic of nanocrystalline Na0.5K0.5NbO3 ceramic green body

Dielectric spectroscopy was applied to porous nanocrystalline Na_0.5K_0.5NbO₃ (NKN) ceramic green body, wherein influences of percolation effect and water adsorption at pore surface of the ceramic green body on dielectric response were examined over wide temperature (150 to 450?K) and frequency (100?Hz to 1?MHz) ranges. Dielectric permittivity of the ceramic green body is about 2–3 orders of magnitude higher than that of pure NKN powder or NKN ceramic. Furthermore, the high dielectric permittivity and high humidity sensitivity of the ceramic green body can appear again with aging a period of time in air. The data from this investigation make potential applications for NKN as a giant dielectric material or a humidity sensing material.     

Effects of Substrate Bias on the Diamond Nanostructure by Reactive Ion Etching

Abstract

Dense and uniform diamond nanocone arrays on titanium substrate were constructed by using bias-assisted reactive ion etching (RIE) of diamond films in a microwave plasma chemical vapor deposition (MPCVD) system. A hydrogen/argon mixture was employed as work gas with ratio of 3/1. The formation of nanocone structure was generated the lengthways physical bombardment/sputtering by argon ions, and selective chemical reaction of graphite and disordered carbons by hydrogen atoms and ions. The structure, size, and density depended on the substrate bias. The surface morphology of diamond film and nanostructures were characterized by field emission scanning electron microscope (FESME), and the composition of diamond film and nanostructures were characterized by Raman spectra. The Stopping and Range of Trons in Matter (SRIM) software was used to simulate the bombardment effect of the diamond film on different Ar⁺ ion incident angles during the etching process. The experimental results showed substrate bias at ?180?V and ?210?V was beneficial to the formation of high density, small size and sharp nanocones, meanwhile larger bias contributed to the formation of large size nanocones. Besides, as-prepared nanocones still maintained significant diamond phase.     

Effect of discharge power density on the properties of Al and F co-doped ZnO thin films prepared at room temperature

ZnO transparent conducting thin films co-doped with aluminium and fluorine (AZO:F) were prepared on glass substrates by RF magnetron sputtering at room temperature. The effect of discharge power density on the microstructure, surface morphology, electrical and optical properties was investigated. From XRD analysis, it was revealed that the intensity of (002) favoured orientation of ZnO films increased with power density from 2.6 to 6.1?W/cm² and then turned to a randomly orientated structure as power density continuously increased to 7.8?W/cm². The film prepared at 6.1?W/cm² showed a better crystallization and microstructure with larger, pyramid-like grains that were approximately 180?nm long and 90?nm wide. As a result, the electrical resistivity of the AZO:F films had a minimum of 4.1?×?10^?4???cm. The improvement in the electrical resistivity of AZO:F films was due to the increase in carrier concentration from 8.8?×?10²⁰ to 1.38?×?10²¹?cm^?3 and the mobility from 5.8 to 11.8?cm² V^?1 s^?1. The increase in carrier concentration with power density was also found to affect the optical property of the films due to the Moss-Burstein shift.     

Improved Performance of Stair-Stepping Buffer-Gate 4H Silicon Carbide Metal Semiconductor Field Effect Transistor

Abstract

The 4H SiliconCarbide metal semiconductor field effect transistor (4H-SiC MESFET) with a buffer layer between the gate and channel (BG) is optimized and a new stair-stepping buffer-gate structure (SBG) is proposed for improving the breakdown characteristics. The terminal technology of breakdown point transfer (BPT) is applied in 4H-SiC SBG-MESFET in order to scatter the electric field lines and transfer the breakdown point. The breakdown mechanism is further investigated by simulating the surface electric field distribution and electrostatic potential contours. The results show that the breakdown voltage is increased from 120?V to 180?V, improved by the rate of 50% while the current density has hardly deteriorated, and thus the current density is improved from 9.35?W/mm to 13.2?W/mm in comparison with BG structure.     

励磁系统中附加调差对电力系统振荡模式阻尼的影响

将附加调差引入菲利蒲-海佛隆模型,分析附加调差对模型参数的影响,推导出附加调差提供的阻尼转矩系数增量?KD随附加调差系数XC的变化是一条二次抛物线,且这条抛物线的特性与励磁参数、发电机参数、运行状况及线路参数有关。证明了此抛物线在以?KD为纵轴、以XC为横轴的坐标系中必经过原点,且与横轴的第2个交点随发电机功角变化而单调变化。根据此抛物线可全面说明附加调差对系统阻尼的影响情况。两机系统及实际互联电网各典型振荡模式的计算结果与理论推导吻合。