TC2M2δ.5钛板冷热翻边成形极限及非对称化研究

TC2Mδ2.5mm钛板室温圆孔翻边成形试验结果表明,除翻边底孔尺寸小于极限值时在唇口边缘发生破裂的正常失效方式之外,冷翻边卸载后制件还出现凸缘平面翘曲、翻边孔口部椭圆化、唇口边缘高度不一致、壁厚分布不均匀等非对称化现象。600℃高温热翻边成形可以有效地提高成形极限,并消除了凸缘平面翘曲和口部椭圆化,但口部高度差以及壁厚不均等非对称化现象依然存在。本文在给出极限翻边系数的同时,对这种非轴对称化程度进行了定量描述,并给出了理论上的分析与解释。     

挤压模具型腔轮廓形状的多目标优化设计

采用刚粘塑性有限元分析和优化算法相结合,利用三次样条函数插值表达挤压模具型腔轮廓形状,以修正的序列二次规划法为优化方法,对挤压模具型腔轮廓形状进行了多目标优化设计,建立了多目标优化的数学模型。优化结果采用有限元软件MARC/AutoForge进行了数值模拟,验证了优化结果的有效性。在气门的实际生产实践中,证明了这种方法对提高模具寿命是十分显著的。     

分子动力学模拟技术及其在金属熔体结构研究中的应用

介绍了分子动力学模拟技术的基本原理、模拟过程及广泛使用的原子间相互作用势函数,综述了该方法在研究金属熔体结构方面的最新成果及今后的发展方向.     

CCWELD:A CIM system for robotic arc welding

ＣＣＷＥＬＤ：ＡＣＩＭｓｙｓｔｅｍｆｏｒｒｏｂｏｔｉｃａｒｃｗｅｌｄｉｎｇ￥ＫＯＮＧＹｕ；ＤＡＩＭｉｎｇ；ＷＵＬｉｎａｎｄＨＵＡＮＧＤｏｎｇｓｈｅｎｇ（ＷｅｌｄｉｎｇＤｅｐａｒｔｍｅｎｔ，ＨａｒｂｉｎＩｎｓｔｉｔｕｅｏｆｔｅｃｈｎｏｌｏｇｙ，Ｈａｒｂ...     

煤焦油蒸馏的新产品-改质沥青的生产

论述了利用热缩聚方法对中温沥青进行改质处理来生产改质沥青 ,提高了沥青的软化点、β树脂含量及结焦值 ;并介绍了生产工艺的特点、主要工艺参数及产品的质量     

丙烯酸酯三元共聚物酸掺杂改性聚苯胺的研究

选择丙烯酸 (AA)、丙烯酸丁酯 (BA)和甲基丙烯酸甲酯 (MMA)三元共聚物对聚苯胺 (PAn)进行改性 ,研究了BA的用量和引发剂浓度对PAn导电率的影响 ,对样品进行DSC、FTIR和SEM测试。结果表明 ,丙烯酸酯三元共聚物酸对PAn有良好的掺杂改性作用 ,当共聚单体 (AA -BA -MMA)组成为 10∶45∶45 (质量比 ) ,引发剂浓度为0 0 5 48mol·L-1时 ,可制得电导率达 1 42 1S·cm-1的导电PAn。     

Preparation of high-strength and high-modulus poly(vinyl alcohol) fibers by crosslinking wet spinning/multistep drawing method

This study is mainly focused on the preparation of high-strength and high-modulus poly(vinyl alcohol) (PVA) fibers by crosslinking wet spinning and multistep drawing. High strength as well as high modulus can be achieved by introduction of the crosslinks into the oriented chains to reduce entanglement degree and slippage between chains. The relationships between mechanical properties and fine structure of the drawn fibers were examined based on results of measurements of tensile property, thermal property, dynamic viscoelasticity, crystallinity, and orientation. The strength and Young's modulus of the drawn fibers are approximated to 1.82 and 51.76 GPa, respectively. The fiber has a sharp melting peak temperature that appeared at 236.7°C in the differential scanning calorimeter (DSC) curve. Our results indicate the multistep drawing procedure is superior to the conventional one-step drawing procedure. These excellent mechanical properties can be directly attributed to their high orientation of the amorphous chains. © 1994 John Wiley & Sons, Inc.     

Chrome-free single-step in-situ phosphatizing coatings on a Ti-6Al-4V titanium alloy

Surface pretreatment, such as chromate conversion, is generally required for the organic coating on Ti-6Al-4V titanium alloys. The surface modification process facilitates bond formation between the titanium surface and adhesives or paints. However, the hexavalent chromate used in the conversion coating is carcinogenic and must be eliminated. Recently, the “green chemistry” technique of in-situ phosphatizing coatings (ISPC) has been developed at Northern Illinois University. In this study, a polyester-melamine coating system catalyzed by p-toluene sulfonic acid is used as a control paint and applied to bare (paint 1) and chromated (paint 3) Ti alloy panels. The arylphosphonic acid employed as an in-situ phosphatizing reagent (ISPR) is used to formulate ISPC polyester-melamine paint and to react in-situ with the metal surface when ISPC paint is applied on bare Ti panels (paint 2) and chromated Ti panels (paint 4). After soaking in 3% NaCl solution for 1500 hr, the electrochemical impedance, |Z|, was measured as 10⁹, 10¹⁰, 10¹⁰, and 10¹⁰ ohm-cm² for paints, 1, 2, 3, and 4, respectively. After 1000 hr salt spray (fog) testing, a disbondment from the “X” scribe is observed as 13 and <0.5, <1, <1 mm for paints 1, 2, 3, and 4, respectively. The simultaneous reaction of the ISPR in catalyzing the polymerization of paint film and forming the metal-phosphate layer is the reason for the superior ISPC paint performance. Presented at the 79th Annual Meeting of the Federation of Societies for Coatings Technology, in Atlanta, GA, Nov. 5–7, 2001. Department of Chemistry and Biochemistry, DeKalb, IL 60115.     

Functionalized carbon nanotubes: properties and applications

Carbon nanotubes can be functionalized via amidation and esterification of the nanotube-bound carboxylic acids. The solubility of these functionalized carbon nanotubes makes it possible to characterize and study the properties of carbon nanotubes using solution-based techniques. Representative results concerning the solubility, dispersion, defunctionalization, and optical properties of the functionalized carbon nanotubes are presented. Several examples for the use of functionalized carbon nanotubes in the fabrication of polymeric carbon nanocomposites, the probing of nanotube-molecule interactions, and the conjugation with biological species are highlighted and discussed.     

纳米四氧化三铁磁性微粒的表面有机改性

通过液相共沉淀法制备了纳米四氧化三铁溶胶，利用油酸对纳米粒子体进行表面改性和萃取实验，获得油酸包覆的四氧化三铁微粒。采用FT—IR和高分辨透射电镜对改性后的纳米粉体进行结构和形貌的表征。研究结果表明油酸与四氧化三铁纳米粒子间存在化学键结合。油酸对纳米四氧化三铁微粒进行改性，并且对纳米粒子进行包覆，使外表面形成保护层阻止粒子团聚，改性后的四氧化三铁微粒与有机物具有良好的相溶性，采用表面改性显著改善了纳米四氧化三铁微粒的性能指标。