石墨表面镀Si对石墨/Al复合材料热物理性能的影响

Effects of Si coated on graphite surface on the thermal and mechanical properties of graphite/Al composites

研究了石墨粒径及表面镀Si处理对石墨/Al复合材料热物理性能的影响。结果表明:在盐浴过程中石墨表面形成了SiC层,这不仅增强了石墨-Si/Al复合材料的界面结合力,而且抑制了Al4C3相的产生。随着石墨鳞片体积分数从50%增加到70%,复合材料X-Y方向的热导率从492 W/(m·K)增加到654 W/(m·K),而且体积分数为50%的镀Si石墨/Al复合材料抗弯强度达到了81 MPa,相比未镀覆的提高了53%,是理想的定向导热电子封装材料。随着石墨粒径从500μm减小到150μm,石墨-Si/Al复合材料X-Y面方向的热导率由654 W/(m·K)降低到445 W/(m·K),但Z方向的热导率和复合材料抗弯强度变化不明显。

The effect of Si coated on the graphite surface and the grain diameter of graphite flake on thermal and mechanical properties of graphite/Al composites was researched.The results show that the SiC layer is formed during coating process,which is beneficial to suppress the formation of Al4C3 phase and enhance the interface bonding.The thermal conductivity in X-Y plane direction of the graphite-Si/Al composite increases from 492 W/（m·K）to654 W/（m·K）as the volume fraction of the graphite increases from 50vol% to 70vol%.The flexure strength of graphite/Al composites with 50vol% graphite approachs 81 MPa,which increases by 53%than that of the uncoated graphite/Al.The thermal conductivity in X-Y plane direction of graphite-Si/Al composite decreases from654 W/（m·K）to 445 W/（m·K）with the grain diameter of the graphite decreases from 500μm to 150μm.However,the thermal conductivity in Zplane direction and the flexure strength exhibit no significant change.