| In recent years,the development of integrated microelectronic devices has highlighted the problem of poor reliability and life caused by thermal aggregation.With many advantages like high strength and high intrinsic thermal conductivity of carbon fiber,carbon fiber reinforced resin composites have great potential for heat management fields.For devices mainly composed of carbon fiber composites,it is necessary to enhance the out-of-plane thermal conductivity on the basis of maintaining the mechanical properties of carbon fiber composites.The thermal conductivity of each phase and the interfacial connection between the two phases are the key factors affecting the thermal conductivity of the composites.Due to the confidentiality of production technology and high cost,there are few researches on high-modulus carbon fiber,which own high thermal conductivity.Based on this,in order to enhance the thermal conductivity of carbon fiber composites,the construction of high thermal conductivity layer onto carbon fiber and the filling of resin with high thermal conductivity filler have been carried out.The changes of physical and chemical properties of the two phases,the interfacial connection state of the two phases and the thermal conductivity and interlayer shear strength of the corresponding composites have been analyzed.The main research contents and results are as follows:For the construction of high thermal conductivity layer on the surface of carbon fiber,through continuous equipment,materials modification and additives addition,the dense filler layer was formed on the surface of high-modulus carbon fiber by continuous co-deposition of copper and boron nitride,and the corresponding high-modulus carbon fiber epoxy resin-based composites were prepared.The structural evolution of the fiber surface before and after the treatment was studied by SEM,FTIR,XPS and EDX.The effects of the co-deposited layer on the out-of-plane thermal conductivity and interlaminar shear strength of the composites were analyzed.The effects of the co-deposited layers on the interlaminar shear strength and out-of-plane thermal conductivity of the composite were also analyzed.The results shows that the hydroxy groups generated on BN could promote dispersion by forming hydrogen bonds with hydron and the HNO3treatment before electrodeposition could make the fiber grooves deeper and help the deposition of copper crystals on the fiber surface;after 60 s co-deposition,the wavy filler layers are uniformly adhered to the fiber surface and the diameter of carbon fiber increases from 4.96μm to 9.09μm;the filler layers could produce mechanical embedding with the matrix and form thermal conductivity paths through the resin matrix together with the fibers.The out-of-plane thermal conductivity and interlaminar shear strength of the composite are 2.33 W/（m·K）and 77.7 MPa,increased by 153%and 8%,respectively.For the filling of resin with highly thermally conductive filler,boron nitride and pitch-based carbon fiber were used as thermally conductive fillers.The carbon-fiber-reinforced resin matrix composites were prepared by mechanical blending method at a constant temperature for a long period of time.The dispersion and interfacial connection states of the fillers were studied by SEM,XRD and EDX.The effects of filler content and filler type on the out-of-plane thermal conductivity and interlaminar shear strength of the composites were analyzed to further explore the synergistic effects of multi-scale fillers in resin and carbon-fiber-reinforced composites.The results show that the addition of high thermal conductivity fillers could effectively improve the thermal conductivity of the composites,and their reinforcement effects are influenced by the content and type;the thermal conductivity of the filler-filled resin composites gradually improves with increasing content,0.426 W/（m·K）and 0.410 W/（m·K）with 15 wt%BN and SCF respectively,while the change trend of the thermal conductivity of the carbon-fiber-reinforced resin composites is different,the enhancement of which is lower than former;the multi-scale fillers show obvious synergistic effect of enhanced thermal conductivity in resin,the proportion of which with optimal heat conduction is different at different temperatures.While in carbon fiber composites,there is small difference of thermal conductivity among different temperature,though in decline. |
