具有三维连续网络结构的聚合物基导热复合材料研究进展

热界面材料可以有效地将高温电子器件的热量快速传递到热管理元件,以缓解电子器件过热而导致的元件寿命恶化的问题。近年来,由聚合物和高导热填料制成的聚合物基复合材料因其密度低、导热性能可调而受到广泛关注。不同于传统的填料随机分散的复合材料,在聚合物基体中构建三维连续网络结构可以显著增加填料/填料接触、降低导热渗透阈值和界面热阻,显著改善复合材料的导热性能。首先,简要分析了聚合物基导热复合材料的导热机制。其次,总结了具有连续网络结构的聚合物基导热复合材料的构筑工艺,主要包括基于三维导热填料网络的预构筑、基于聚合物颗粒/粉末的后加工、基于聚合物纤维/织物的后加工、基于聚合物胶乳的铸膜或絮凝等工艺。再次,系统总结了不同类型的导热填料对聚合物复合材料导热性能的影响,主要包括金属填料、陶瓷填料、碳基填料及其混杂填料等。最后,对具有三维连续网络结构的聚合物基导热复合材料的发展前景进行了展望。     

木陶瓷/金属复合材料的研究现状

总结了木陶瓷/金属复合材料及其预制体模板的制备机理和制备方法的研究现状;详细介绍了木陶瓷/金属复合材料的力学性能、热学性能、阻尼性能和摩擦学性能及其应用等方面的研究成果;探讨了木陶瓷/金属复合材料的发展前景及当前存在的问题;最后提出了一种以麻纤维织物为模板材料制备纤维织物遗态陶瓷/金属复合材料的新思路.     

连续纤维增强SiC复合材料制备工艺与性能研究进展

综述了国内外碳纤维与碳化硅纤维增强碳化硅复合材料的制备工艺与性能的研究进展,并介绍了其氧化性能及防护措施.认为连续纤维增强SiC复合材料的制备工艺复杂,成本较高,生产周期长,但是如果采用连接技术制备成陶瓷/金属复合构件使用,既有利于降低成本,又能够扩大该先进陶瓷基复合材料的应用范围.目前,国内对连续纤维增强的SiC复合材料与金属(如高温合金等)的连接技术研究较少.     

纤维独石陶瓷复合材料的研究进展

纤维独石陶瓷复合材料是一种新型的陶瓷材料,具有独特的三维微结构排列和力学性能,尤其是高韧性,在结构陶瓷方面具有潜在的应用前景。本文总结了国内外纤维独石结构陶瓷基复合材料的制备工艺、组成与结构及性能,提出了仍需研究的问题。     

陶瓷纤维及其陶瓷基复合材料

介绍了连续陶瓷纤维及其陶瓷基复合材料在近年的研究进展,重点评述了陶瓷纤维以及陶瓷基复合材料制备工艺的研究现状,并对连续纤维陶瓷基复合材料的前景进行了展望。     

双连续TiC/Fe复合材料的制备和性能

以聚氨酯海绵为前驱体,以TiC微粉为原料并添加少量还原铁粉、羰基铁粉及钛粉为烧结助剂,用有机前驱体浸渍法制备具有三维网络结构的TiC多孔陶瓷,研究了聚氨酯海绵的孔径、浆料涂覆次数等因素对TiC多孔陶瓷的孔隙率和孔棱直径的影响。在此基础上采用无压浸渗工艺将Fe基体与TiC多孔陶瓷复合,制备出一种双连续结构的TiC/Fe复合材料。分析了复合材料的物相组成,观察了其宏观结构与微观结构,并测试了复合材料内的硬度分布。结果表明,TiC多孔陶瓷的结构完整,孔隙率和孔棱直径可控;复合材料具有双连续结构,TiC与Fe结合良好,两相结合区的硬度呈梯度变化。     

前苏联纤维复合材料的研究状况

前苏联纤维复合材料的研究状况本文回顾了前苏联１９８２～１９９２年间，碳／碳、碳／金属、陶瓷／陶瓷复合材料及其制造技术。主要引用的文摘包括：苏联文摘杂志、化学文摘、工程索引、工程材料文摘、陶瓷文摘、世界陶瓷文摘和先进材料文摘。１．碳／碳复合材料１９８８...     

网络陶瓷增强金属复合材料的研究现状

综述了目前网络陶瓷增强金属基复合材料的发展及研究现状,重点介绍了网络陶瓷预制体及复合材料的主要制备工艺,并指出了各工艺的特点.评述了网络陶瓷增强金属复合材料的性能特点,指出了目前网络陶瓷增强金属基复合材料存在的问题及解决方法,并展望了对网络陶瓷增强金属基复合材料未来的发展方向.     

O-3型压电陶瓷/聚合物复合材料的制备工艺新进展

0－3型压电陶瓷／聚合物复合材料具有单相压电陶瓷或聚合物所不具备的良好的综合性能,因此引起了人们广泛的兴趣和研究。本文综述了0－3型压电复合材料的制备工艺及相应复合材料的压电性能,重点介绍了水解－聚合法、凝聚－胶体法、溶液聚合法3种新型制备工艺,简要分析各种制备工艺的优缺点,为压电陶瓷／聚合物复合材料（甚至是纳米级压电复合材料）的进一步研究、开发和应用提供依据。     

具有网络互穿结构的木质陶瓷复合材料

提出以新型环境材料多孔木质陶瓷（WCMs)为骨架，用真空压力浸渍工艺制备了WCMs／金属网络互穿结构复合材料，并研究了材料的性能，结果表明，复合材料浸渍效果良好，组织均匀且网络互穿结构明显，与基体木质陶瓷比较，复合材料的导热性能和力学性能都得到明显改善，组成相的互锁和韧性相的桥接作用可能是材料性能改善的主要机制。     

烧结温度对焦磷酸钙/Ti-35Nb-7Zr复合材料微观组织及力学性能的影响

为改善β型Ti-Nb-Zr合金的生物活性,添加20wt%的焦磷酸钙(CPP)生物陶瓷,利用放电等离子烧结技术制备20CPP/Ti-35Nb-7Zr生物复合材料。借助XRD、SEM及力学测试方法等研究不同烧结温度(1 000~1 200℃)下复合材料的微观组织及力学性能,揭示其组织演变对力学性能的影响机制。结果表明:20CPP/Ti-35Nb-7Zr复合材料主要由β-Ti相基体、少量残留α-Ti相及金属-陶瓷相(CaTiO_3、Ti_2O、CaO、CaZrO_3和TixPy)组成;随着烧结温度升高,复合材料中β-Ti相和金属-陶瓷相逐渐增多;金属与陶瓷之间的剧烈反应导致金属-陶瓷相的形态结构发生变化,复合材料中金属-陶瓷相从颗粒状析出物演变成连续网状组织,起到割裂基体的作用。20CPP/Ti-35Nb-7Zr复合材料的压缩弹性模量和抗压强度随着烧结温度的升高而增大,其中压缩弹性模量从64.0GPa增加至71.4GPa,金属-陶瓷相形态结构变化起主导作用。因此,控制20CPP/Ti-Nb-Zr复合材料中金属-陶瓷相的形态结构将有利于改善其力学性能。     

Optimization of bond strength between gold alloy and porcelain through a composite interlayer obtained by powder metallurgy

The purpose of this study was to evaluate the influence of a composite interlayer (at the metal-ceramic interface) on the shear bond strength of a metal-ceramic composite when compared with a conventional porcelain fused to metal (PFM).Several metal-ceramic composites specimens were produced by hot pressing. To identify which was the best composition for the interlayer several composites, with different relations of metal/ceramic volume fraction, were bonded to metal and to ceramic substrates. The bond strength of the composites to substrates was assessed by the means of a shear test performed in a universal test machine (crosshead speed: 0.5 mm/min) until fracture. Some interfaces of fractured specimens as well as undestroyed interface specimens were examined with optical microscope and scanning electron microscope (SEM/EDS).The shear bond strength results for all composites bonded to metal and to ceramic substrates were significantly higher (>150 MPa) than those registered in the upper range of conventional porcelain fused to metal (PFM) techniques (∼80 MPa). The use of a composite interlayer proved to enhance metal/ceramic adhesion in 160%.     

Ti35Nb7Zr-xHA生物复合材料的微观组织与性能研究

为了改善Ti-Nb-Zr合金的生物活性,采用放电等离子烧结(SPS)技术制备了不同羟基磷灰石(HA)含量的Ti35Nb7Zr-xHA(x=0、5、10、20(质量分数,%))生物复合材料,研究了HA含量对复合材料微观组织、力学性能及体外生物活性的影响。结果表明,复合材料主要由β-Ti、α-Ti、HA及陶瓷相(Ti_xP_y、CaTiO_3、Ti_2O、CaO)组成;HA含量增加会导致β-Ti减少而α-Ti和陶瓷相明显增多;与Ti-35Nb-7Zr合金(E:45GPa,σ:1 736 MPa)相比,HA含量为5%和10%时,复合材料的抗压强度分别为1 662MPa和1 593MPa,弹性模量分别为48GPa和49GPa,综合力学性能与Ti-35Nb-7Zr合金接近,展现出良好的力学性能,而过高的HA含量(20%)会导致复合材料弹性模量明显升高(E:55GPa)、抗压强度急剧下降(σ:958 MPa),复合材料的力学性能降低;体外生物活性实验表明,加入10%HA的复合材料在人工模拟体液(SBF)中浸泡7d后表面生成了大量的类骨磷灰石层,与Ti-35Nb-7Zr合金相比,其显示出更优异的体外生物活性。     

Electrical conductivity of composites: a percolation approach

A percolation model has been developed for describing electrical conductivity in particle and short-fibre metal-ceramic composites. Results apply quantitatively to three-dimensional microstructures with fully controlled characteristics (particle shape, orientation and distribution).     

陶瓷增强铝合金互渗相复合材料的半固态设计和成形

目的 开发一种针对金属-陶瓷互渗相复合材料生产的高效方法,以提升该类材料在高温高负荷环境中的使用寿命和工作可靠性。方法 采用数值扫描技术研究了半固态成形过程,以铝合金为金属成分、氧化铝开孔体为陶瓷成分,制备了复合材料。通过模拟2种腔体(开放式和封闭式)的金属陶瓷压铸成形过程模拟不同的模腔设计,详细分析了腔体内的压力水平及其分布情况,探讨了压铸温度、金属液相体积分数等参数对材料成形质量的影响。结果 封闭模腔能够在成形过程中产生更加均匀的压力分布,有助于减少如气孔、未渗透区域等材料缺陷,并提高金属与陶瓷之间的互渗质量。与封闭模腔相比,开放模腔在控制材料均匀流动和确保渗透效果方面效果较差。结论 采用封闭模腔的半固态成形工艺能显著提升金属-陶瓷互渗相复合材料的整体质量和性能,有效减少成形缺陷,为高性能金属-陶瓷复合材料的制备提供了一种有效路径。     

Electron Beam Curing of Advanced Composites

1. IntroductionRadiation processing is the utilization of ionizingradiation, usually photons or electron beam (EB), toproduce useful physical and chemical changes in a ma-tenal. The research on radiation treatment of polymers has continued for a long time. There has beena considerable development about the use of EB inthe production of advanced composites for the use ofaerospace and other industries in recede y6ars. EBcuring of composites involves using electrons as ionizing radiation to ini…     

Structural performance of discontinuous metal matrix composites

Abstract

Discontinuous metal matrix composites (i.e. short fibre and particle reinforced materials) have attained a significant degree of scientific and technological maturity as advanced structural materials. Initial commercialisation has been achieved, with the unique combinations of mechanical and physical properties afforded by metal-ceramic systems proving appropriate for a variety of structural and semistructural applications. In recent years there has been important consolidation in the understanding of basic structural properties in such composites, which are addressed in the present review. The outstanding requirement for an improved understanding of damage tolerance characteristics in these materials is particularly noted. ‘Mesoscopic’ materials architectures (e.g. laminated and functionally graded materials) are also discussed, and the associated potential for development offracture resistant discontinuous metal composite materials highlighted.     

High strain rate characteristics of 3-3 metal-ceramic interpenetrating composites

3-3 interpenetrating composites (IPCs) are novel materials with potentially superior multifunctional properties compared with traditional metal matrix composites. The aim of the present work was to evaluate the high strain rate performance of the metal-ceramic IPCs produced using a pressureless infiltration technique through dynamic property testing, viz. the split Hopkinson's pressure bar (SHPB) technique and depth of penetration (DoP) analysis, and subsequent damage assessment. Though the IPCs contained rigid ceramic struts, the samples plastically deformed with only localised fracture in the ceramic phase following SHPB. Metal was observed to bridge the cracks formed during high strain rate testing, this latter behaviour must have contributed to the structural integrity and performance of the IPCs. Whilst the IPCs were not suitable for resisting high velocity, armour piercing rounds on their own, when bonded to a 3 mm thick, dense Al₂O₃ front face, they caused significant deflection and the depth of penetration was reduced.     

Mechanical and electrical response of carbon nanotube-based fabric composites to Hopkinson bar loading

The numerous structural applications of composites, coupled with their complex, rate-dependent mechanical behavior necessitate research into their mechanical response under dynamic loading scenarios. While the damage mechanisms of composites under dynamic compression loading are well-understood, measuring the occurrence of damage in a non-invasive manner is challenging. Toward this end, we investigate the electrical response of an embedded percolating carbon nanotube network in woven fabric/epoxy composites to dynamic compression loading. The percolating network is established through the use of a non-uniform dispersion of carbon nanotubes, achieved using a fiber sizing agent. The resulting conductive network is sensitive to delamination and damage occurring near the fiber surfaces. The dynamic mechanical response of the composite specimens is explored using Hopkinson bar methodology. Definite increases in baseline resistance of the conductive composite specimens are seen after repeated impacts demonstrating the ability of the carbon nanotube network of these conductively modified composites to respond electrically to damage induced during dynamic loading.     

细菌纤维素/聚乳酸互穿网络复合材料的结晶与熔融

为了研究细菌纤维素(BC)网络结构对聚乳酸(PLA)结晶与熔融过程的影响,以PLA为基体,BC为增强体,通过PLA-三氯甲烷溶液与BC-无水乙醇分散液的共混扩散制备了具有互穿网络结构的BC/PLA生物复合材料。采用SEM、偏光显微镜(POM)、DSC和莫志深(MO)模型研究了复合材料的微观形态、球晶形貌、非等温结晶动力学和熔融行为。结果表明:采用溶液共混扩散法可得到以BC为骨架、PLA缠绕其表面的互穿网络结构的复合材料。随降温速率增加,BC/PLA复合材料的结晶温度、熔融温度和相对结晶度均下降。BC可作为异相成核剂,适量添加可同时提高BC/PLA复合材料的结晶速率和相对结晶度,细化球晶尺寸。MO模型可较好地描述BC/PLA复合材料的非等温结晶动力学行为。