温度和频率对环氧树脂/碳化硅晶须复合材料交流非线性特性的影响

Effect of Temperature and Frequency on AC Nonlinear Properties of Epoxy Resin/Silicon Carbide Whisker Composites

为了研究不同温度和频率下的交流非线性电导和介电性能,该文制备了纯环氧及不同掺杂质量分数的环氧树脂/碳化硅晶须复合材料,分别使用透射电子显微镜、场发射扫描电子显微镜、X射线衍射仪、动态热机械分析仪和差示扫描量热仪研究了碳化硅晶须填料的改性效果、试样的断面微观形貌、填料和试样的物相结构信息、试样的热机械特性和试样的玻璃化转变温度,通过介电谱仪偏压模块测试了材料的交流电导率和介电常数,分析了温度和频率对材料交流非线性电导和介电特性的影响。结果表明:对于相同掺杂质量分数的环氧树脂/碳化硅晶须复合材料,在相同频率下,随着温度的升高,其非线性交流电导率系数减小,非线性介电常数系数、非线性交流电导率开关场强和非线性介电常数开关场强均增大;在相同温度下,随着频率的增加,其非线性交流电导率系数和非线性介电常数系数均减小,非线性交流电导率开关场强和非线性介电常数开关场强均增大。不同温度和频率下的非线性电导特性和非线性介电特性的产生机理分别通过双肖特基势垒模型和界面电荷弛豫模型进行解释。研究结果为EP/SiCw复合材料的高温高频应用提供了实验和理论依据。

To investigate the AC conductive and dielectric properties at different temperatures and frequencies, the pure epoxy and epoxy resin/silicon carbide whisker(EP/SiCw) composites with different doping mass fractions were fabricated. The surface modification effect of the SiCw fillers, the crosssection micro-morphology of the samples, the phase structure information of the SiCw fillers and samples, the thermomechanical properties and glass transition temperature of the samples were investigated by transmission electron microscope, field emission scanning electron microscope, X-ray diffraction, dynamic mechanical analysis and differential scanning calorimetry, respectively. The effects of temperature and frequency on AC conductivity and dielectric properties of the samples were analyzed by the AC bias voltage module of the dielectric spectrum analyzer. The results show that for the same frequency and doping concentration, the nonlinear AC conductivity coefficient decreases with the increase of temperature, whereas the nonlinear dielectric constant coefficient, nonlinear AC conductivity switching field strength and nonlinear dielectric constant switching field strength increase with the increase of temperature. For the same temperature and doping concentration, the nonlinear AC conductivity coefficient and nonlinear dielectric constant coefficient both decrease with the increase of frequency, whereas the nonlinear AC conductivity switching field strength and nonlinear dielectric constant coefficient both increase with the increase of the frequency. The generation mechanisms of the nonlinear conductive property and nonlinear dielectric property at different temperatures and frequencies are explained by the double Schottky barrier model and the interface charge relaxation model,respectively. The results can provide experimental and theoretic reference to the high-temperature and high-frequency application of the EP/SiCw composites.