P2O3—B2O3—Al2O3—SrO—BaO玻璃中的Yb^3＋非辐射能量转移下E …

本文研究了共掺Ｅｒ＾３＋／Ｙｂ＾３Ｐ２Ｏ３－Ｂ２Ｏ３－Ａｌ２Ｏ３－ＳｒＯ－ＢａＯ玻璃的能量转移过程。实验中制备了高掺杂Ｂｂ＾３＋离子的双掺Ｅｒ＾＃＋／Ｙｂ＆＾３＋的磷酸盐玻璃样品。在Ｅｒ＾３＋／Ｙｂ＾３＋掺杂比率〉１：１８（ｍｏｌ％）时,观测到了基于Ｙｂ＾３＋离子至Ｅｒ＾３＋离子能量转移下Ｅｒ＾３＋（＾３Ｉ１３／２→＾４Ｉ１５／２）的增强发射和ｂ＾３＋（＾２Ｆ７１／→＾２Ｆ５／２）发射的减弱,当Ｂ     

电化学腐蚀对Si：Er^3＋材料中Er^3＋发光的影响

利用离子注入技术在硅片表面制备了不同Ｅｒ＾３＋注入剂量的Ｓｉ：Ｅｒ＾３＋样品，研究了电化学过程对Ｓｉ：Ｅｒ＾３＋样品中Ｅｒ＾３＋发光的影响。样品低温红外光致发光实验证明：电化学过程同样在Ｓｉ：Ｅｒ＾３＋样品的硅基质晶体中引入了大量的深能级局域态，且这些局域态较难用退火方式进行控制。     

TlGaS2和TlGaS2：Er^3＋单晶的光致发光性质

用布里奇曼法生长出ＴｌＧａＳ２单晶和ＴｌＧａＳ２：Ｅｒ＾３＋单晶。生成的单晶，其光致发光与深层能级及Ｅｒ＾３＋离子能级有关。由施主－受主对复合引起的宽发射谱带，对ＴｌＧａＳ２单晶，在５９６、６１０、６９６和７１６ｎｍ处；对ＴｌＧａＳ２：Ｅｒ＾３＋单晶，则在６３２和７５９ｎｍ处。由Ｅｒ＾３＋引起的窄发射谱带，在５５２、５５９、６６６、８１３、８１６和８２７ｎｍ处。     

上转换氟化物光纤激光器

氟化物玻璃是一种性能优异的激光基质材料。本文介绍了稀土离子上转换发光的机理和光纤顺的基本结构，综述了近几年来对掺Ｔｍ＾３＋、Ｐｒ＾３＋、Ｅｒ＾３＋、Ｈｏ＾３＋和Ｎｄ＾３＋的上转换氟化物光纤激光器的研究和应用概况。     

（Y,Zn,Sr）3（P,VO4）：Eu^3＋,Bi^3＋发光性质的研究

合成了组成为（Ｙ，Ｚｎ，Ｓｒ）３（Ｐ，ＶＯ４）：Ｅｕ＾３＋，Ｂｉ＾３＋的荧光材料，经Ｘ射线结构分析确定为Ｚｎ３（ＰＯ４）２结构，属于单斜晶系，空间群为Ｐ２１／ｎ。讨论了基质组成对Ｅｕ＾３＋离子发光性质的影响，用Ｙ＾３＋取代了一部分Ｚｎ＾２＋；用ＶＯ４取代了一部分ＰＯ４由于基质的４３６ｎｍ发射与Ｅｕ＾３＋的激发态能级的能量重叠，Ｅｕ＾３＋产生较强的５９８ｎｍ和６１８ｎｍ发射。另外，掺入少量Ｂｉ＾３＋     

高温高压合成的硅酸锶有铕铋的发光特性

用高温高压方法合成了Ｓｒ２ＳｉＯ４Ｅ＾３＋ｕ，Ｂｉ＾３＋和ＳｒＳｉＯ３Ｅｕ＾３＋＿，Ｂｉ＾３＋，研究了合成压力对其发光性能的影响，与用溶胶－凝胶共沉淀法和常压高温法合成的产品作比较，常压制备的ＳｒＳｉＯ３Ｅｕ＾３＋，Ｂｉ＾３＋为六角结构，而在２．３４－４．１０ＧＰａ的合成压力范围内，它转变为赝正交结构；常压下Ｓｒ２ＳｉＯ４；Ｅｕ＾３＋，Ｂｉ＾３＋，为单斜结构，在４．２ＧＰａ的合成压力下，未发现其结     

共沉淀包膜掺杂法制备氧化锌压敏陶瓷粉料条件的研究

本研究旨在建立以ＺｎＯ为主体，五元掺杂物共沉淀包膜法制备氧化锌压敏陶瓷用粉料的新方法。在实验测定Ｚｎ＾２＋及Ｂｉ＾３＋、Ｓｂ＾３＋、Ｃｏ＾２＋、Ｍｎ＾２＋、Ｃｒ＾３＋碳酸盐－氢氧化物沉淀溶解度曲线的基础上，研究各种因素对恒定ＺｎＯ及五元掺杂物组成ｍｏｌ％的影响，确定最佳共沉淀包膜条件。     

（BiAl）YIG薄膜的生长感生磁各向异性

从理论和实验上分析了Ｆｅ＾３＋和Ｆｅ＾２＋对（ＢｉＡ）ＹＩＧ薄膜的生长感各向异性的贡献，掺Ｂｉ导致的生长磁感生各向异性，来源于Ｅｉ＾３＋改变了Ｆｅ＾３＋的零场劈裂，其大小取决于Ｂｉ＾３＋含量及在十二面体位的择优分布，高价离子和氧空位形成的Ｆｅ＾２＋在八面体位的择优分布，对生长感生磁各向异性也有贡献。     

CsCdF3:Cr3+晶格畸变及其Cd2+-空位研究

按照零场分裂（ＺＦＳ）的三阶微扰理论和叠加晶场模型,建立了ＺＦＳ参量Ｄ与ＣｓＣｄＦ３：Ｃｒ＾３＋晶格结构之间的定量关系,同时考虑了晶格畸变和Ｃｄ＾２＋空位对零场分裂参量Ｄ的贡献,计算了ＣｓＣｄＦ３：Ｃｒ＾３＋晶体的零场分裂参量Ｄ,计算结果与实验符合甚好,证明了晶格畸变和Ｃｄ＾２＋空位的存在,同时得到ｒ＾３＋离子的Ｆ＾－离子向中心Ｃｒ＾３＋离子分别移动Ｘ１＝０．００２９１ｎｍ,Ｘ２＝０．００１ｎｍ,     

新型两段光纤双向泵浦掺铒光纤放大器

运用工程化掺铒光纤放大器模拟理论方法，基于国产１４８０ｎｍＬＤ泵源和国产Ｅｒ＾３＋／Ａｌ＾３＋共掺杂光纤，从理论和实验上分析比较了新型两段级联泵浦与普通单段双泵两种结构ＥＤＦＡ的增益、功率和限幅特性。两段级联ＥＤＦＡ比单段ＥＤＦＡ的增益、３ｄＢ饱和输出功率和动态范围分别提高了５ｄＢ、１ｄＢ和１２ｄＢ，泵浦光转换效率改善了２０％。     

短纤维混杂增强PP复合泡沫材料的力学性能

将助剂预混与二次挤出工艺相结合制备含短纤维预发泡粒料, 并用型内二次发泡工艺制备了短炭纤维(SCF)、 短玻璃纤维(SGF)混杂增强聚丙烯(PP)复合泡沫材料。研究了在纤维总质量分数不变时, SCF与SGF的相对含量、 增强纤维与PP的界面性能及泡沫体的表观密度对PP复合泡沫材料的发泡效果和力学性能的影响。结果表明: SGF和SCF的同时加入能够改善PP的高温熔体强度, 获得孔径较小且均一的类球形的闭孔PP泡沫体。SGF和SCF混杂增强提高了PP复合泡沫材料的强度和模量, 且增强效果高于单一纤维, 当纤维总质量分数为15%, 且SGF ∶SCF为1 ∶1时(质量比), PP复合泡沫材料的抗弯强度和抗压强度最高, 而SGF ∶SCF为3 ∶1时, PP泡沫复合材料的冲击韧性和压缩模量达到最大值 。泡沫体的表观密度对PP复合泡沫材料的冲击韧性和抗压强度影响显著, 当表观密度从0.32g/cm3增至0.45g/cm3时, 冲击韧性和抗压强度分别从4.29kJ/m2和6.57MPa 提高到17.87kJ/m2和20.57MPa。      

超高分子量聚乙烯纤维热行为的研究

用ＤＳＣ法对不同拉伸倍率的ＵＨＭＷ－ＰＥ纤维，分别进行了松弛和定长状态下的热分析。在松弛状态下，拉伸３０、４０倍纤维的ＤＳＣ谱图上，出现三重熔融峰，表明，纤维中除折迭链和伸直链结晶外，还存在另一种结晶形态。在定长状态下纤维的熔融吸热峰会发生很大变化，若在适当温度下进行热处理，可加速结晶形态的转化过程。     

导电导磁改性短碳纤维的制备及电磁特性的研究

对短碳纤维进行氧化处理后,采用原位氧化沉淀聚合法使苯胺/磁流体或者苯胺/磁粉在其表面进行包覆反应,制备出具备有一定长径比的导电导磁改性短碳纤维.采用扫描电镜、X射线能谱及X射线衍射对改性碳纤维的形貌、化学组成进行了分析,利用PNA-LN5230A微波网络测试仪测定了其在频率2GHz以下的复介电常数和复磁导率,对比分析了两种不同方法制备的改性碳纤维的电磁参数以及2mm厚度下的吸收损耗.结果表明:聚苯胺/磁流体包覆的碳纤维(改性SCF-A)包覆层完整、致密,Fe含量为2.86at%;聚苯胺/磁粉包覆碳纤维(改性SCF-B)的包覆层外观完整、比较松散,Fe含量为3.12at%.改性SCF-A的复介电常数的实部大于改性SCF-B,但其虚部则小于改性SCF-B;改性SCF-B的复磁导率整体大于改性SCF-A.在频率2GHz以下,改性SCF-A的最大吸收损耗为3.06dB,改性SCF-B的最大吸收损耗为4.14dB.     

THE EFFECT OF MISALIGNMENT ON THE FATIGUE STRENGTH OF WELDED CRUCIFORM JOINTS

Abstract— The effect of axial misalignment on the fatigue strength of load-carrying transverse cruciform welded joints was investigated using experimental and fracture mechanics methods. Where failure occurred by cracking from the weld toe, misalignment significantly reduced the fatigue strength. The reduction could be predicted using a nominal stress concentration factor (SCF). Misalignment had less effect where failure was due to cracking through the weld metal; an expression was deduced for the SCF in this case. For fracture mechanics assessments, an expression for an effective stress intensity factor using the SCF and stress intensity factors for aligned welds was shown to agree with the finite element (FE) results. Predictions of the effect of misalignment using the FE results agreed with experimental data. Misaligned transverse load-carrying cruciform joints should be assessed for fatigue failure from the toe using the same SCF as for a butt weld with the same misalignment. For failure through the throat, an alternative expression for the SCF is recommended. Fracture mechanics assessments of misaligned joints should be carried out using an effective stress intensity factor derived from the SCF and stress intensity factors for aligned joints. These recommendations are now incorporated in British Standard PD 6493:1991.     

On the formation of liquid inclusions in some solution-grown crystals: (I) sodium-cadmium formate

The formation of liquid inclusions in sodium-cadmium formate (SCF) single crystals has been studied. Crystals were grown on seeds by slow cooling of unstirred aqueous solution. It was found that liquid inclusions in SCF are a result of convective flow around a crystal. The results are briefly analysed from theoretical considerations.     

包覆型短碳纤维等效介电常数的模拟计算

基于等效电磁理论,推导了频率小于2GHz的包覆型短碳纤维的等效电磁参数方程.采用Matlab6.5软件对包覆型短碳纤维的等效电磁参数进行了模拟和计算,并讨论了包覆层体积分数和短碳纤维长径比对等效电磁参数的影响.结果表明,等效介电常数随着包覆层体积分数的增大而增大,当短碳纤维的长径比小于30时影响较大.包覆型短碳纤维的等效电磁参数方程的模拟结果与实验结果相对误差小于10%.     

GMT流动成型纤维取向研究

GMT材料流动成型后玻纤在平面内发生取向，导致模压件呈各向异性，本研究从成型后制品上取样烧尽树脂，由扫描仪获取纤维数值图像，用Photoshop软件将图像反相，增强，再利用MATLAB软件确定纤维取向分布，研究表明，GMT单向流动成型时纤维沿流动方向取向，随流动距离增大，取向趋向更为明显，而均匀双向拉伸流动纤维取向程度较小，与片材相比，材料力学性能沿取向方向增大，但垂直取向方向材料性能变差。     

Friction and wear of epoxy/TiO2 nanocomposites: Influence of additional short carbon fibers, Aramid and PTFE particles

An epoxy-based nanocomposite containing graphite powder (7 vol%) and nano-scale TiO₂ (4 vol%) was developed for tribological evaluation. A series of composites containing additional fillers such as short carbon fibers (SCF), Aramid and polytetrafluoroethylene (PTFE) particles was developed and evaluated in adhesive and low amplitude oscillating wear modes. The incorporation of SCF and Aramid particles resulted in a remarkable improvement in the sliding wear resistance. However, SCF impaired the low amplitude oscillating wear resistance. The further addition of PTFE to the SCF filled nanocomposites reduced the friction and wear under both wear conditions. However, an adverse effect of PTFE was found for the Aramid particles filled nanocomposites. Under sliding conditions, the lowest wear rate and coefficient of friction showed the 2–4 vol% PTFE filled SCF nanocomposite. Aramid particles containing nanocomposites (without PTFE) exhibited the best wear and friction behavior under low amplitude oscillating wear conditions among the selected composites. The wear mechanisms were studied by scanning electron microscopy.     

短切碳纤维表面处理对木粉/高密度聚乙烯复合材料性能的影响

木粉（WF）填充增强高密度聚乙烯（HDPE）复合材料具有良好的环境效益,少量引入短切碳纤维（SCF）可进一步提高其力学性能。为改善SCF与WF/HDPE复合材料中塑料基体的界面结合,提高SCF在WF/HDPE复合材料中的增强作用,采用气相、液相及气液双效氧化3种表面处理方式处理SCF,通过挤出工艺制备短切碳纤维增强木粉/高密度聚乙烯复合材料（SCF-WF/HDPE）,探讨了不同处理方法对SCF-WF/HDPE复合材料性能的影响。SEM观察显示,表面处理增大了SCF的表面粗糙度,可提高其与基体的界面结合;动态力学性能分析证实碳纤维提高了存储模量。测试结果表明：表面处理过的短切碳纤维可使SCF-WF/HDPE复合材料的力学性能、热力学性能和蠕变性能均得到显著提高,其中气相表面处理的效果最好。对比WF/HDPE复合材料,SCF-WF/HDPE的拉伸强度提高了34.5%,弯曲强度提高了23%,冲击强度提高了54.7%。     

Performance of Polyaniline-coated Short Carbon Fibers in Electromagnetic Shielding Coating

Combined nitric acid oxidation method and polyaniline （PANI）-coated method were applied to modify the surface properties of short carbon fibers （SCF）. The electrical and mechanical properties of acrylic coatings with 50 wt pct PANI-coated carbon fiber were investigated by using scanning electron microscope （SEM）, UV-Vis spectrophotometer, four-probe method and the coaxial cable method. The results of the pH measurement and XPS （X-ray photoelectron spectroscopy） patterns showed that the oxygen functional groups, such as -OH and -COOH, were attached on the carbon fiber surfaces after oxidation treatment. The XPS analysis of PANl-coated oxidized SCF （PAOSCF） revealed that PANI may bond on the surface of oxidized SCF with chemical bonds. SEM images and surface roughness analyses showed that PANl-coated layer changed the surface morphology. Compared with SCF/acrylic coating, the surface resistivity of PAOSCF/acrylic coating decreased from17.1 to 5.3 Ω/sq and the shielding efficiency （SE） value increased from 1.54 to 23.3 dB.