为研究石墨烯导电填料的加入对环氧材料电导机理的影响,制备了不同填料质量比下石墨烯/环氧树脂复合材料。通过测量得到该复合体系的渗流阈值为质量分数1.35%,选择了石墨烯填料质量分数为0.3%、远低于渗流阈值的复合材料进行研究。利用...为研究石墨烯导电填料的加入对环氧材料电导机理的影响,制备了不同填料质量比下石墨烯/环氧树脂复合材料。通过测量得到该复合体系的渗流阈值为质量分数1.35%,选择了石墨烯填料质量分数为0.3%、远低于渗流阈值的复合材料进行研究。利用高温高场强电导电流测试系统,测量了纯环氧材料和石墨烯/环氧复合材料在50、80和100℃下和0.24~14.4 k V/mm场强下的极化电流曲线。研究结果表明：直流电压作用下,两种材料的极化电流衰减速率均随场强和温度的增加而增大。随着场强的增大,两种材料的电导机理均发生了从欧姆电导到空间电荷限制电流理论（SCLC）为主导的转变,且这种转变电导电流场强阈值（Ethi）随温度的升高而降低。石墨烯填料的加入使环氧材料电导电流密度活化能增大,且活化能随着场强的增加逐渐降低,石墨烯/环氧复合材料在高场强区的电导机理受SCLC和隧道效应共同影响。展开更多
The nonlinear J-E characteristics under self-heating equilibrium for conductive composites based on high density polyethylene were studied. The results show that there are identical conduction mechanisms under self-he...The nonlinear J-E characteristics under self-heating equilibrium for conductive composites based on high density polyethylene were studied. The results show that there are identical conduction mechanisms under self-heating equilibrium for the composites with various initial resistivities determined by filler content or ambient temperature. The nonlinear conduction behavior was involved in the limited microstructure transformations of the conducting network induced by electrical field applied and the corresponding self-heating effect. A reversible thermal fuse (RTF) model was suggested to interpret the physical origin of the nonlinear J-E characteristics.展开更多
The electrical and optical effects of particles on the nano aluminum film deposited by thermal evaporation was investigated. From the characterization results of scanning electron microscope（SEM）, the accumulation i...The electrical and optical effects of particles on the nano aluminum film deposited by thermal evaporation was investigated. From the characterization results of scanning electron microscope（SEM）, the accumulation in tens of nanometers had been observed. The current-voltage（I-V） curve of the sample indicates its nonlinear electrical characters expecting the corresponding nonlinear optical properties. By the theoretical calculation, nonlinear conduction of the carrier transportation may result from the barrier-well-barrier structure, where negative resistance and Coulomb blockade effect appears. The simulation results are approximately matched with the experimental results. By testing the fluorescence emission spectrum of the sample, peaks were found to be located at 420 and 440 nm. In addition, the full width at half maximum（FWHM） had been obviously broadened by means of adding 2, 5-diphenyloxazole（DPO）. Therefore, discrete energy levels could be estimated inside those particles.展开更多
直流气体绝缘输电管道(direct current gas insulated lines,DC-GIL)电场分布受温度梯度、运行电压、金属微粒等诸多因素影响,具有非常大的不确定性,给绝缘设计和运行稳定性带来挑战。非线性电导材料能够自适应地调控直流设备电场分布,...直流气体绝缘输电管道(direct current gas insulated lines,DC-GIL)电场分布受温度梯度、运行电压、金属微粒等诸多因素影响,具有非常大的不确定性,给绝缘设计和运行稳定性带来挑战。非线性电导材料能够自适应地调控直流设备电场分布,有望突破DC-GIL绝缘子设计瓶颈。为了兼顾电场调节作用和损耗特性,建立100 kV直流GIL仿真模型,对比研究运行工况下传统绝缘子、表层电导非线性(surface nonlinear conductivity,SNC)绝缘子和体电导非线性(bulk nonlinear conductivity,BNC)绝缘子的电场分布及损耗功率。通过分析非线性电导(nonlinear conductivity,NC)参数对气固沿面电场调控作用和损耗特性的影响规律,发现SNC绝缘子的电场畸变率先随着欧姆区电导率和非线性系数的增大而快速下降,而后趋于平稳。理想情况下,SNC绝缘子的NC参数应处于电场调节作用的"饱和临界线",且欧姆区电导率最低。而BNC绝缘子的电场调节作用仅依赖于非线性系数,降低欧姆区电导率可降低绝缘子功率损耗。缩比绝缘子实验结果证实了SNC绝缘子非线性参数直接影响DC-GIL沿面闪络电压。展开更多
非线性复合绝缘材料有助于解决电力系统绝缘设备或部件电场分布不均匀的难题。为此介绍了Zn O压敏陶瓷微球及其复合绝缘材料的制备方法,实现了同时具有非线性电导特性和非线性介电特性随外加电场而自适应变化的复合材料。材料的非线性...非线性复合绝缘材料有助于解决电力系统绝缘设备或部件电场分布不均匀的难题。为此介绍了Zn O压敏陶瓷微球及其复合绝缘材料的制备方法,实现了同时具有非线性电导特性和非线性介电特性随外加电场而自适应变化的复合材料。材料的非线性特性主要由压敏微球填料决定,而对于绝缘材料基体的要求较为宽松;当材料中的压敏微球体积分数超过30%时,复合物具有很好的非线性特性,其电导非线性系数可达到16.9而介电常数也能够比线性区增加5倍以上;材料的压敏电压也能够根据填料体积分数进行一定范围内的调节。采用非线性电导特性和非线性介电特性的复合材料取代传统电缆附件中控制电缆接头电场应力的压控管和应力锥的材料对电场的应力控制效果更好,对于110 k V的交流电缆终端内电场分布的仿真计算表明,在应力锥绝缘部分采用非线性材料能够将关键位置处的场强从采用固定材料时的4.7 k V/mm降低至2.2 k V/mm以下,并且材料的电导率越大、非线性系数越大时,均匀场强的效果越好。展开更多
文摘为研究石墨烯导电填料的加入对环氧材料电导机理的影响,制备了不同填料质量比下石墨烯/环氧树脂复合材料。通过测量得到该复合体系的渗流阈值为质量分数1.35%,选择了石墨烯填料质量分数为0.3%、远低于渗流阈值的复合材料进行研究。利用高温高场强电导电流测试系统,测量了纯环氧材料和石墨烯/环氧复合材料在50、80和100℃下和0.24~14.4 k V/mm场强下的极化电流曲线。研究结果表明：直流电压作用下,两种材料的极化电流衰减速率均随场强和温度的增加而增大。随着场强的增大,两种材料的电导机理均发生了从欧姆电导到空间电荷限制电流理论（SCLC）为主导的转变,且这种转变电导电流场强阈值（Ethi）随温度的升高而降低。石墨烯填料的加入使环氧材料电导电流密度活化能增大,且活化能随着场强的增加逐渐降低,石墨烯/环氧复合材料在高场强区的电导机理受SCLC和隧道效应共同影响。
基金the National Advanced Material Committee of China (NAMCC)，国家自然科学基金
文摘The nonlinear J-E characteristics under self-heating equilibrium for conductive composites based on high density polyethylene were studied. The results show that there are identical conduction mechanisms under self-heating equilibrium for the composites with various initial resistivities determined by filler content or ambient temperature. The nonlinear conduction behavior was involved in the limited microstructure transformations of the conducting network induced by electrical field applied and the corresponding self-heating effect. A reversible thermal fuse (RTF) model was suggested to interpret the physical origin of the nonlinear J-E characteristics.
基金Supported by the 973 Program(No.2014CB932103)the 863 Program(No.2013AA032501)the National Natural Science Foundation of China(NSFC No.21676015)
文摘The electrical and optical effects of particles on the nano aluminum film deposited by thermal evaporation was investigated. From the characterization results of scanning electron microscope（SEM）, the accumulation in tens of nanometers had been observed. The current-voltage（I-V） curve of the sample indicates its nonlinear electrical characters expecting the corresponding nonlinear optical properties. By the theoretical calculation, nonlinear conduction of the carrier transportation may result from the barrier-well-barrier structure, where negative resistance and Coulomb blockade effect appears. The simulation results are approximately matched with the experimental results. By testing the fluorescence emission spectrum of the sample, peaks were found to be located at 420 and 440 nm. In addition, the full width at half maximum（FWHM） had been obviously broadened by means of adding 2, 5-diphenyloxazole（DPO）. Therefore, discrete energy levels could be estimated inside those particles.
文摘非线性复合绝缘材料有助于解决电力系统绝缘设备或部件电场分布不均匀的难题。为此介绍了Zn O压敏陶瓷微球及其复合绝缘材料的制备方法,实现了同时具有非线性电导特性和非线性介电特性随外加电场而自适应变化的复合材料。材料的非线性特性主要由压敏微球填料决定,而对于绝缘材料基体的要求较为宽松;当材料中的压敏微球体积分数超过30%时,复合物具有很好的非线性特性,其电导非线性系数可达到16.9而介电常数也能够比线性区增加5倍以上;材料的压敏电压也能够根据填料体积分数进行一定范围内的调节。采用非线性电导特性和非线性介电特性的复合材料取代传统电缆附件中控制电缆接头电场应力的压控管和应力锥的材料对电场的应力控制效果更好,对于110 k V的交流电缆终端内电场分布的仿真计算表明,在应力锥绝缘部分采用非线性材料能够将关键位置处的场强从采用固定材料时的4.7 k V/mm降低至2.2 k V/mm以下,并且材料的电导率越大、非线性系数越大时,均匀场强的效果越好。
