聚氨酯基压电阻尼复合材料阻尼性能的研究

用绝缘电阻测试仪研究了以聚氨酯(PPG2000)为基体材料,锆钛酸铅(PZT)为压电填料,导电炭黑(CB)为导电填料的压电复合阻尼材料的导电性能。以渗流理论分析了对于PPG2000导电炭黑的渗流阈值,以及PZT的加入对导电炭黑渗流阈值的影响。采用动态力学性能分析(DMA)技术对聚氨酯压电陶瓷复合阻尼材料的阻尼性能进行研究,分析了导电性能对其阻尼性能的影响。     

永久导电辐射交联聚烯烃泡沫塑料的开发与研究

以低密度聚乙烯(LDPE)为主体,超导碳黑为导电填料,偶氮二甲酰胺(AC)为发泡剂,制备了永久导电聚烯烃泡沫材料(IXPE)。对辐射交联聚乙烯发泡材料的导电性能、辐照剂量进行了研究,并对永久导电辐射交联聚乙烯发泡材料的综合性能进行了分析。结果表明,在优选的几种超导碳黑中,当T-1添加50份,辐照剂量为13.5r/min+1.5MeV+15mA+2层时,能得到性能优异的永久导电辐射交联聚烯烃泡沫塑料,体积电阻率可以降到105Ω·cm。     

聚合物/碳纳米管复合导电材料的研究进展

基于碳纳米管(CNTs)的导电性能,对以碳纳米管为导电填料的复合导电材料的制备方法及国内外研究进展进行了综述。重点介绍了几种常见聚合物/CNTs复合导电材料的研究现状。展望了此类导电材料的发展前景。     

不同导电剂对硅碳复合负极性能的影响

导电剂的添加对负极材料在电池的循环性能中能否发挥其最优的性能起重要作用.文章以纳米硅碳复合负极材料为研究对象,研究了KS-6(导电炭黑)及SUPER-P(导电石墨)两种导电剂对硅碳复合负极材料电化学性能的影响.通过扫描电镜、电池测试系统分析了两种导电剂、负极片的形貌及负极片的电化学性能.结果表明:添加粒度细小的球形状的...     

碳纤维协同碳纳米管改性聚乳酸的性能研究

选用可完全生物降解的聚乳酸材料作为导电抗静电聚合物复合材料的基体,以阵列碳纳米管(CNT)为主要电介质,碳纤维(CF)为增强材料和辅助导电剂,采用熔融共混法制备生物降解导电高分子材料。研究表明,含2%碳纳米管的聚乳酸(PLA)表面电阻率可达到1010Ω/sq,即可达到抗静电材料的要求;添加1%的碳纤维(CF),制备成PLA/CNT/CF导电复合材料,碳纤维不但可以提高材料的导电性能,还显著改善材料的拉伸强度和冲击性能,导电性和冲击强度均提高了4倍。     

新型碳纤维复合导电材料的制备以及性能研究

研究了新型碳纤维复合导电材料的制备方法及其导电性能,提出了基于电气相沉积(CVD)法和热解法的新型碳纤维复合导电材料制备方法。采用电化学调节方法和稳态控制方法,进行碳纤维复合导电材料的光生电荷的分离;采用热解法对碳纤维复合导电材料进行热解分离及衍射谱分解;将羧甲基纤维素盐加入到碳纤维复合导电材料的溶解质中,确保制备过程中碳纤维复合导电材料的导电性。对性能进行研究时,通过分析碳纤维复合导电材料的电磁特征,对导电材料的电阻率、材料制备成本、功率损耗及效率进行分析。研究得知,制备的新型碳纤维复合导电材料的导电性能较好,输出稳态性较强。     

浓乳液模板法制备导电聚苯乙烯泡沫材料

以两亲性导电聚合物聚(3,4-乙烯二氧噻吩)-聚苯乙磺酸（PEDOT/PSS）作为表面活性剂,碳纳米管为导电填料,通过浓乳液模板法制备了聚苯乙烯导电泡沫复合材料（PS-MWCNTs）。用扫描电镜观察了不同碳纳米管负载量对材料泡孔形貌的影响,并通过导电性能测试研究了材料的电导率随碳纳米管及导电表面活性剂含量的变化规律。结果表明,填料负载量可以影响泡沫材料的泡孔形态与导电性能,并且具有表面活性剂性能的导电聚合物的引入大大提高了PS-MWCNTs泡沫材料的导电性。     

聚苯胺掺杂的研究与进展

从掺杂方法着手综述了聚苯胺(PAn)导电材料的特征及导电原理,重点介绍了物理掺杂(离子注入)和质子酸掺杂的特点,及掺杂对PAn结构及导电性能的影响,并简介了这两种掺杂方法所得PAn导电材料的优点和应用.     

聚苯胺和聚吡咯导电高分子吸波材料进展

介绍了吸波材料的吸波机理及分类,总结了近年来导电高分子在电磁屏蔽领域的研究进展。重点概述了基于聚苯胺(PANI)、聚吡咯(PPy)的两大类导电高分子复合吸波材料,着重强调导电高分子组分的引入在一定程度上增强材料的介电损耗与电阻损耗,提高匹配阻抗,极大地改善材料吸波性能,最后指出导电高分子吸波材料的发展趋势。     

聚苯胺/改性胶粉导电材料的制备及其性能研究

将废旧轮胎胶粉用硅烷偶联剂(KH-560)处理得到改性胶粉,然后以过硫酸铵为引发剂,采用化学原位聚合法制备了聚苯胺/改性胶粉导电材料。采用傅里叶变换红外光谱仪(FTIR)、扫描电子显微镜(SEM)、能谱仪(EDS)、四探针测试仪及电化学工作站等仪器,研究了原料配比、反应温度、反应时间对聚苯胺/改性胶粉导电材料导电性能的影响,并分析了胶粉改性及复合材料导电机理。结果表明,通过改性能明显提高胶粉分散性能;当温度为10 ℃,过硫酸铵与苯胺摩尔比为1∶1,盐酸浓度为1.0 mol/L,反应时间10 h时,制得的聚苯胺/改性胶粉导电材料的电导率为4.79 S/cm。     

PP/硅灰石/EPDM体系组分与形态结构对冲击韧性的影响

利用双螺杆挤出机制备PP/硅灰石/EPDM三元复合物,通过扫描电镜和冲击实验等研究了该复合物组分变化和形态结构对其力学性能,特别是冲击韧性的影响。控制组分和形态结构可以得到冲击韧性和刚度同时提高的力学性能均衡的复合材料。     

Properties 0–3 PZT–Portland cement composites

Smart structural composites are multifunctional structural materials which can perform functions such as sensing strain, vibration reduction and are essential because of their relevance to mitigation and structural vibration control. Cement-based piezoelectric composites have been developed as smart structural composites. The goal of this work is to produce cement-based piezoelectric composites using lead zirconate titanate (PZT) and Portland cement (PC) with xPZT–(1 − x)PC (where x = 0.3, 0.6 and 0.9). The composites were pressed together and cured in 100% RH curing chamber for 3 days before measurements. Dielectric constant (_r) at room temperature and piezoelectric coefficient (d₃₃) of the 0–3 piezoelectric PZT–Portland cement composites with different PZT content were investigated. The results show these composites have _r and d₃₃ values of up to 536 and 87 pC/N, respectively, and there is a good potential for the application of these cement-based piezoelectric composites in civil engineering.     

Preparation of interpenetrating alumina–copper composites

To prepare interpenetrating alumina–copper composites, alumina foams were activated with titanium coating by chemical vapor deposition and then were infiltrated with molten copper by expendable casting process. The microstructure and phase composition of the composites were analyzed, and bending strength, electrical conductivity, friction and wear properties were tested. The results showed that the bonding between ceramic and metal was fine in the composites while no reactions took place between them because of the undissolved titanium coating. With increase of ceramic fraction, the electrical conductivity of the composite decreased, whereas the bending strength increased. The composite failure occurred by ductile fracture of the metal followed by fracture of the ceramic. The wear rate of the composites decreased with increase of ceramic fraction. And the wear of the composites was featured with ceramic struts peeling compared with ploughing and adhering wear for pure copper.     

Mechanical and thermophysical properties of carbon/carbon composites with hafnium carbide

Carbon/carbon (C/C) composites with addition of hafnium carbide (HfC) were prepared by immersing the carbon felt in a hafnium oxychloride aqueous solution, followed by densification and graphitization. Mechanical properties, coefficients of thermal expansion (CTE), and thermal conductivity of the composites were investigated. Results show that mechanical properties of the composites decrease dramatically when the HfC content is greater than 6.5 wt%. CTE of the composites increases with the increase of HfC contents. The composites with addition of 6.5 wt% HfC show the highest thermal conductivity. The high thermal conductivity results from the thermal motion of CO in the gaps and pores, which can improve phonon–defect interaction of the C/C composites. Thermal conductivities of the composites decrease when the HfC content is greater than 6.5 wt%, which is due to formation of a large number of cracks in the composites. Cracks increase the phonon scattering and hence restrain heat transport, which results in the decrease of thermal conductivity of the composites.     

Comparative study of interphase evolution in polysiloxane resin-derived matrix containing carbon micro and nanofibers during thermal treatment

The work presents the results of research on composite materials made of silicon-containing polymer-derived ceramic matrix composites (PDC-Cs) and nanocomposites (PDC-NCs). Carbon micro and nanofibers (CFs and CNFs) were used as reinforcements. The interactions between carbon micro and nanofibers and polysiloxane matrix, as well as interphase evolution mechanism in composite samples during their heating to 1000 °C were studied. CF/resin and CNF/resin composites were prepared via liquid precursor infiltration process of unidirectionally aligned fibers. After heating to 700 °C–800 °C, decomposition of the resin in the presence of CNFs led to the formation of fiber/organic-inorganic composites with pseudo-plastic properties and improved oxidation resistance compared to as-prepared fiber/resin composites. The most favourable mechanical properties and oxidation resistance were obtained for composites and nanocomposites containing the maximum amount of carbon nanoparticles precipitated in the SiOC matrix during the heat treatment at 800 °C. The precipitated carbon phase improves fiber/matrix adhesion of composites.     

Appropriate thickness of pyrolytic carbon coating on SiC fiber reinforcement to secure reasonable quasi-ductility on NITE SiC/SiC composites

Pyrolytic carbon (PyC) coating of silicon carbide (SiC) fibers is an important technology that creates quasi-ductility to SiC/SiC composites. Nano-infiltration and transient eutectic-phase (NITE) process is appealing for the fabrication of SiC/SiC composites for use in high temperature system structures. However, the appropriate conditions for the PyC coating of the composites have not been sufficiently tested. In this research, SiC fibers, with several thick PyC coatings prepared using a chemical vapor infiltration continuous furnace, were used in the fabrication of NITE SiC/SiC composites. Three point bending tests of the composites revealed that the thickness of the PyC coating affected the quasi-ductility of the composites. The composites reinforced by 300?nm thick coated SiC fibers showed a brittle fracture behavior; the composites reinforced 500 and 1200?nm thick PyC coated SiC fibers exhibited a better quasi-ductility. Transmission electron microscope research revealed that the surface of the as-coated PyC coating on a SiC fiber was almost smooth, but the interface between the PyC coating and SiC matrix in a NITE SiC/SiC composite was very rough. The thickness of the PyC coating was considered to be reduced maximum 400?nm during the composite fabrication procedure. The interface was possibly damaged during the composite fabrication procedure, and therefore, the thickness of the PyC coating on the SiC fibers should be thicker than 500?nm to ensure quasi-ductility of the NITE SiC/SiC composites.     

Effect of heat treatment on the mechanical properties of PIP–SiC/SiC composites fabricated with a consolidation process

Continuous SiC fiber reinforced SiC matrix composites (SiC/SiC) have been considered as candidates for heat resistant and nuclear materials. Three-dimensional (3D) SiC/SiC composites were fabricated by the polymer impregnation and pyrolysis (PIP) method with a consolidation process, mechanical properties of the composites were found to be significantly improved by the consolidation process. The SiC/SiC composites were then heat treated at 1400 °C, 1600 °C and 1800 °C in an inert atmosphere for 1 h, respectively. The effect of heat treatment temperature on the mechanical properties of the composites was investigated, the mechanical properties of the SiC/SiC composites were improved after heat treatment at 1400 °C, and conversely decreased with increased heat treatment temperature. Furthermore, the effect of heat treatment duration on the properties of the SiC/SiC composites was studied, the composites exhibited excellent thermal stability after heat treatment at 1400 °C within 3 h.     

Fabrication and magnetic properties of cobalt-dispersed-alumina composites

High-density cobalt-dispersed-alumina (Co/Al₂O₃) composites were successfully prepared by hot-pressing of alumina-cobalt composite powders with fine cobalt 30 nm in diameter. The nanocomposite powders were prepared by co-deposited processing of Al³⁺and Co²⁺, followed by calcination and selective reduction. The phase composition of Co/Al₂O₃ composites were -Al₂O₃, fcc-Co and a little amount of hcp-Co. Microstructural investigations revealed that submicron-sized cobalt particles were dispersed homogeneously at alumina grain boundaries, forming intergranular composites. Meanwhile growth and coalescence of cobalt particles occurred with increasing Co-content. The ferromagnetic properties of the composites were measured, because of the magnetic dispersions, which indicated a functional value of Co/Al₂O₃ composites. The effects of grain size and the residual stresses on magnetic properties for Co/Al₂O₃ system were discussed in detail.     

Effect of oxidation inhibitor on the low energy tribological behavior of carbon-carbon composites

In this study, the tribological performance of carbon-carbon composites impregnated with different amounts of MoSi₂ as an oxidation inhibitor were investigated. The results of the friction tests indicated that the carbon-carbon composites underwent an abrupt transition of the coefficient of friction at the frictional temperature range of 150-180°C. And the composites made with MoSi₂, exhibited lower frictional coefficient and wear rate in comparison with the composites made without MoSi₂. The composites made with 4 wt% MoSi₂ showed an improvement in activation energies for wear resistance when compared with the other composites under the present condition. These results were probably due to the consequence that the friction and wear properties of carbon-carbon composites are sensitive to the friction temperature and can be largely dependent on the adhering force between fibers and matrix-MoSi₂, the reduction of porosity, and the formation of a lubricative, powdery, debris film, formed on the friction surfaces of the carbon samples.     

Fabrication of 2D C/ZrC–SiC composite and its structural evolution under high-temperature treatment up to 1800 °C

Two-dimensional C/ZrC–SiC composites were fabricated by chemical vapor infiltration (CVI) process combined with a modified polymer infiltration and pyrolysis (PIP) method. Two kinds of ZrC slurries (ZrC aqueous slurry and ZrC/polycarbosilane slurry) were employed to densify composites before the PIP process. The as-produced C/ZrC–SiC composites exhibited better mechanical properties than the C/SiC composites densified only by CVI and PIP process. Structural evolution for C/ZrC–SiC composites treated in the range 1200–1800 °C mainly consisted of the change of SiC whiskers and the decomposition of polymer derived ceramic.