SrTiO3微纳米线的制备与亲疏水性

采用水热法，使用层状钛酸盐纳米线和氢氧化锶作为前驱物，在一定反应温度和反应时间的条件下简单地制备出了超细SrTiO3粉体。结果表明，只有在反应条件和反应物配比合适时才能得到纯的SrTiO3粉体。用X-射线粉末衍射仪和扫描电镜对SrTiO3粉体进行了表征。结果表明，所制备的SrTiO3粉体绝大部分为线状，长度约20μm，直径100～500nm。用接触角仪对所制备的SrTiO3粉体的亲疏水性进行了研究。结果表明，随着反应时间的延长，反应产物SrTiO3的纯度逐渐增加，由原来的完全亲水性转变为疏水性，接触角为36．820。     

Analysis of the abnormal resistance in AlGaN/GaN heterostructure＇s ohmic contact tests

Ti/Al/Ti/Au and Ti/Al/Ni/Au ohmic contacts were fabricated on AlGaN/GaN heterostructure under different temperatures of rapid thermal processing （RTP）. Since abnormal resistance values were observed during the contact resistance testing,the surface morphology and contact borders of the samples were analyzed to determine the physical mechanism. Such abnormal phenomenon is found to originate from cracking of the AlGaN layer during RTP,flowing of Ti/Al metallic liquid along the crevices,and continuous reaction of the metallic liquid with AlGaN/GaN. Such processes result in abnormal conduction channels. The possible mechanism of the crevice formation was discussed,and the possible solutions to avoid the crevices were proposed.     

Examination of wire electrical discharge machining of Al2O3p/6061Al composites

Alumina particle reinforced 6061 aluminum matrix composites (Al₂O₃p/6061Al) have excellent physical and chemical properties than those of a traditional metal; however, their poor machinability lead to worse surface quality and serious cutting tool wear. In this study, wire electrical discharge machining (WEDM) is adopted in machining Al₂O₃p/6061Al composite. In the experiments, machining parameters of pulse-on time were changed to explore their effects on machining performance, including the cutting speed, the width of slit and surface roughness. Moreover, the wire electrode is easily broken during the machining Al₂O₃p/6061Al composite, so this work comprehensively investigates into the locations of the broken wire and the reason of wire breaking.The experimental results indicate that the cutting speed (material removal rate), the surface roughness and the width of the slit of cutting test material significantly depend on volume fraction of reinforcement (Al₂O₃ particles). Furthermore, bands on the machined surface for cutting 20 vol.% Al₂O₃p/6061Al composite are easily formed, basically due to some embedded reinforcing Al₂O₃ particles on the surface of 6061 aluminum matrix, interrupt the machining process. Test results reveal that in machining Al₂O₃p/6061Al composites a very low wire tension, a high flushing rate and a high wire speed are required to prevent wire breakage; an appropriate servo voltage, a short pulse-on time, and a short pulse-off time, which are normally associated with a high cutting speed, have little effect on the surface roughness.     

汽车地毯模具的计算辅助设计与铸造

将CAD／CAM技术运用铸造模具的设计与铸造过程中，缩短了模具设计，制造周期，提高了模具的尺寸和形位精度，使模具制造更加适应当前汽车款式不断更新的趋势。     

基于Pro/TOOLKIT曲轴加工尺寸标注的智能化研究

本文阐述了轴类零件智能化技术标注尺寸与公差的基本原理及专家知识,针对发动机曲轴的结构和加工制造特点,对其产品的特征进行了分析研究,并以Pro/Engineer作为基础软件环境,应用Pro/TOOLKIT程序开发技术在VC 6.0环境下对Pro/Engineer进行了二次开发,对建立曲轴的参数化尺寸驱动的特征库和知识库进行了研究,从而实现曲轴加工尺寸标注的智能化.     

Crystal structure and switchable optical properties of yttrium hydride films covered by palladium layer

1　INTRODUCTIONTherare earthhydridefilmswithswitchableop ticalpropertieswerefirstlydiscoveredbyHuibertsetal[13] andhaveattractedmoreandmoreinterestre cently .Huibertsetal[1,2 ] foundthatthefilmsofYHxandLaHx exhibitremarkablereversiblechangesintheiropticalpropertiesduringhydrogenation/dehy drogenationprocess .Bychangingthehydrogen gaspressureorbyelectrochemicalmeans,thefilmscanbecontinuouslyandreversiblyswitchedfromashinymirrortoatransparentwindowinafractionofasec ond[3,4 ] .Thesubsequen…     

工艺参数对合成ZnO／Ag纳米复合抗菌剂产率的影响

通过正交实验，研究了反应温度、反应时间、反应物配比对ZnO／Ag纳米复合抗菌剂合成产率的影响规律。获得了高产率合成ZnO／Ag纳米复合抗菌剂的优选工艺条件：反应温度为10～25℃，ZnSO4与NH4HCO3的摩尔比为1：2-2．5，ZnSO4与NH4HCO3的反应时间为2．5～3h，AgNO3与NH4HCO3的摩尔比为1：1．5～2，反应时间为0．5h，ZnO／Ag的产率超过98％。XRD、TEM和SAED结果表明：ZnO／Ag纳米复合抗菌剂为具有纤锌矿结构的ZnO和立方结构的Ag组成。粒径为15～25nm，分散性较好。     

摩托车曲柄锻模高速加工

介绍了锻模的高速加工，论述了实施高速加工的支撑技术。     

SiCp/2024 复合材料棒材半固态挤压数值模拟

SiCp/2024复合材料棒材半固态挤压是一个典型的半固态触变成形过程,尤其对高固相分数(～60%),更接近于塑性加工中超塑性变形机制.对其加工过程进行了数值模拟,以便揭示高固相体积分数半固态触变成性的规律.研究表明稳态触变挤压的关键是在于保证压力下速度与半固态坯料的凝固速度相协调,只有当变形区坯料保持在固相分数较高固-液态或刚凝固完状态时,才能实现稳态的触变挤压过程;随着挤压温度的升高,挤压力减小其等效应力、等效应变值更均匀,且等效应力减小;随着摩擦系数的减小,平均拉应力值减小.     

Co/Cr/Pd多层膜的磁性及其准确性

研究了测量程序对不同Cr层厚度的Co／Cr／Pd多层膜磁性的影响，分析了反磁化机理在不同测量程序中对磁性准确性的影响。