高导热多孔石墨预制体的制备及其性能

以天然鳞片石墨、酚醛树脂以及中间相碳微球为主要原料,制备多孔石墨预制体,经石墨化处理后再与环氧树脂复合,获得高导热石墨/环氧树脂复合材料。研究了素坯成形密度和粉末组成对多孔石墨预制体X-Y方向的导热性能与孔隙率的影响。结果表明:预制体内部石墨片定向排列,酚醛树脂与中间相碳微球连接其间,形成定向多孔网络结构,实现高导热、高孔隙与大孔径的协同。当素坯成形密度为1.4 g/cm^(3),天然鳞片石墨、酚醛树脂、中间相碳微球的含量分别为67.5 mass%、17.5 mass%和15 mass%时,多孔石墨预制体X-Y方向导热性能达到286.97 W/(m·K),气孔率达到44.56%;此时,石墨/环氧树脂复合材料X-Y方向导热性能达到116.81 W/(m·K)、抗压强度为26 MPa,在电子封装领域具有潜在的应用前景。

Mechanical properties and microscopic failure process of exemplary argillaceous interlayer from east China

The landslide disaster caused by the argillaceous interlayer not only destroys buildings,cultivated land,and roads but also seriously endangers human life and safety.This study concerns the mineral composition of selected argillaceous interlayer and their strength characteristics.To study the mineral composition of argillaceous interlayers,8 kinds of samples in the southern Jiangsu region of China were analyzed utilizing X-ray diffraction(XRD).The repeated direct shear strength tests(RDST)were carried out on the undisturbed specimens of the argillaceous interlayer.The results show that the argillaceous interlayer with high content of kaolinite shows ductile failure mode,which means that there is no obvious residual strength in the shear process.The arrangement of mineral particles on the shear surface of the specimens after different shear displacements was observed under the scanning electron microscope(SEM).It was observed that mineral particles on the shear surface showed a more directional arrangement with the increase of shear displacement.Furthermore,the influence of shear direction on the argillaceous interlayer with completely oriented mineral particles was studied through numerical experiments with four shear strength mechanisms proposition proposed.The influence of the mineral arrangement on the action occasion and magnitude of dilatancy component of shear strength is clarified in the shear mechanism.