氧化态SiCp/5052Al复合材料的界面及热导性能

研究了SiC颗粒经不同氧化时间的氧化行为,采用无压渗透法制备了体积分数大于55%的SiCp/Al复合材料,分析了复合材料的微观组织与界面形貌,探讨了氧化及界面反应对复合材料热导性能的影响。结果表明:当SiC颗粒在1100℃氧化时,随着氧化时间的延长,其氧化增重及氧化层的厚度均增加,但氧化时间大于6 h时,其增加速率减缓;经氧化处理后,颗粒尖角明显钝化,所制备复合材料颗粒分布均匀,致密度比颗粒未氧化时要高;且氧化改变了复合材料的界面反应及结合,未经氧化颗粒表面出现了短棒状Al_4C_3,4 h氧化后颗粒表面形成了八面体MgAl_2O_4,6 h氧化后仍有残余的SiO_2;随氧化时间的延长,复合材料热导及界面热传导系数均呈先增大后减小的变化趋势,这与不同氧化时的实际界面状况密切相关。

Interface and Thermal Conductivity of Oxidized SiCp/5052Al Composites

The oxidation behavior of Silicon Carbide Particles (SiCp) was investigated, and oxidized-SiCp reinforced 5052Al matrix composites with SiC volume fraction beyond 55% were prepared by pressureless infiltration. Moreover, the microstructure and interface morphologies of the composites were examined, and its influence on thermal conductivity of the composites was discussed as well. The results show that the oxidation increment of SiCp and the thickness of SiO2 layer increase with the increasing of pre-oxidation time at 1100 °C; when the oxidized time exceeds 6 h at 1100 °C, the rate of the oxidation increment will decline. After oxidation, the sharp edge is obviously passivated for the SiCp; meanwhile, the distribution of the oxidized SiCp in Al alloy matrix is uniform and almost no holes can be found in the composites. Besides, the reaction and combination at the interface are different with the duration time for the oxidation, short-rod-like Al4C3 can be found on the surface of the particles before oxidation, but octahedron MgAl2O4 appears after the oxidation for 4h, and there is still residual SiO2 after the oxidation for 6 h. In addition, the thermal conductivity and interface heat transfer coefficient of the composites both increase at first and then decrease with the increasing of pre-oxidation time, which is closely related with the actual interface status due to different oxidation degrees