Thermal and Mechanical stability of electrically conductive adhesive joints

Post curing of electrically conductive adhesives (silver filled epoxy) by heating at an elevated temperature significantly enhances the thermal and mechanical stability of conductive adhesive joints. The contact electrical resistivity and thickness of a joint with epoxy or silicone based adhesive tend to decrease cycle to cycle upon thermal cycling between 30°C and 50°C and upon compression (up to 0.55 MPa), except for the silicone joint in the absence of compression. The effect of compression is significant in epoxy joint without post curing and in silicone joint, but is insignificant in epoxy joint after post curing, The effect of thermal cycling is significant in epoxy joint without post curing, less significant in silicone joint, and insignificant in epoxy joint after post curing.     

自然老化对导电硅橡胶电阻特性的影响

分析了异电硅橡胶的电阻性特自然老化条件下的变化规律，发现自然老化对导电硅橡胶电阻行性的影响与导电粒子的质量分数有关，并确定了最佳的导电粒子质量分数。     

倒车雷达用双组分缩合型有机硅胶的研制

介绍了倒车雷达用胶的种类、主要区别和各自优势。讨论了α-ω二羟基聚二甲基硅氧烷、粉剂和交联剂、偶联剂对硅橡胶性能的影响，结果表明采用粒径粗细不同的导热粉料进行搭配可获得较好导热性和良好流动性能的缩合型硅橡胶。选用四官能团的交联剂有助于协助提高导热率。KH550／KH792偶联剂和乙烯基偶联剂联合使用能够提高体系对铝和PC粘接性能。     

软模辅助RTM制备舱段缩比件

本文以某型号舱段研制为背景,提出用软模辅助RTM整体成型复杂结构的复合材料构件,依据舱段结构特点,设计了缩比件,并用聚氨酯软模和硅橡胶软模分别成型了碳纤维/环氧复合材料缩比件。研究结果表明,硅橡胶软模和聚氨酯软模都可以成型出外形完整、尺寸准确的缩比件,硅橡胶软模的挤胶效果明显好于聚氨酯软模,但是总体上软模挤胶效果不是很明显,本文对此进行了分析讨论。实验表明,软模辅助RTM可以整体成型内部结构复杂的复合材料构件,本文还对今后的研究提出了设想。     

燃烧器喷口碳化硅灰浆烘炉时出现缺陷的分析及处理

描述了碳化硅灰浆材料由于施工及烘炉不当容易造成的质量缺陷,对出现问题的原因进行了详细的分析,并提出了切实有效的缺陷处理方案。     

硅橡胶耐热性的研究进展

本文综述了硅橡胶的热氧老化机理,归纳了改善硅橡胶耐热性能的主要途径,指出了提高硅橡胶耐热性能的发展方向。     

脱酰胺型RTV硅橡胶的研究

以N—甲基乙酰胺与氯硅烷反应制得酰胺型硅烷；配合α，ω—二羟基聚二甲基硅氧烷和粉体填料，制得室温硫化硅橡胶。研究了酰胺型硅烷的结构及其与α，ω—二羟基聚二甲基硅氧烷的反应活性。结果表明，酰胺型硅烷具有非常高的水解活性，与α，ω—二羟基聚二甲基硅氧烷(107胶)的反应无需加外催化剂；以二官能、多官能度酰胺型硅烷作为硫化体系，与107胶、粉体填料配合，可制得模量低(0．22MPa)、件长率高(1232％)的脱酰胺型室温硫化硅橡胶。     

混凝土建筑接缝用有机硅密封胶的研制

以α,ω-二羟基聚二甲基硅氧烷为基胶,气相法白炭黑和纳米碳酸钙为增强填料,配合自制的扩链剂、交联剂,制得单组分室温硫化、高伸长率、低模量的有机硅密封胶--硅宝-668.该密封胶硫化后邵尔A硬度为10度、100%定伸应力约为0.1 MPa、伸长率达1 600%,并具有良好的施工性能;可用于道路、桥梁、机场等混凝土建筑接缝(伸缩缝)的密封.     

Effect of electric field on viscoelastic properties of a disperse system in silicone gel

In the electrorheological (ER) fluids of disperse systems, the poor dispersion stability of particles often limits the development of practical application of the fluids. This key problem can be settled by the chemical gelation of ER fluids. In the present study, a dimethylsilicone oil‐based gel containing the nonaqueous ER particles was newly created. The dynamic properties of viscoelasticity in the sample silicone gel were examined under applied DC electric fields of up to 2.0 kV/mm using a sinusoidal oscillating rheometer with low frequencies of 1 Hz or less. The particle behavior and the shearing deformation in the sample gel were also observed using a microscope, a CCD camera, and a color video monitor. When an electric field was applied to the sample gel, the gap between the electrodes was bridged by the chains of particles arranged in the direction of the electric field. Consequently, it is shown that the electroviscoelastic effect of the gel can be controlled by the electric field. © 2002 Wiley Periodicals, Inc. Electr Eng Jpn, 142(2): 1–9, 2003; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.10098     

国内外有机硅行业的发展态势

简述国内外有机硅行业的现状及发展趋势。