Microstructures of Carbon Fiber and Hybrid Carbon Fiber-Carbon Nanofiber Reinforced Aluminum Matrix Composites by Low Pressure Infiltration Process and Their Properties

Carbon fiber reinforced pure Al, A336 alloy and carbon fiber-carbon nanofiber reinforced A336 alloy composites were successfully fabricated by low-pressure infiltration process, aiming for development the carbon fiber reinforced aluminum matrix composites with high thermal conductivity and mechanical property used as functional materials and structural materials, respectively. Carbon fiber of 10 vol% and hybrid carbon fiber-carbon nanofiber of 10 vol% were used to fabricated preforms for the low-pressure infiltration process. Afterwards, pure Al and Aluminum alloy under a temperature of 1073K were infiltrated into the preforms under an applied pressure of 0.4MPa in Ar environment. Microstructural and mechanical performances of the composites were investigated. Microstructure observations indicated that SiO2 binder was coated on the surface of carbon fiber and distributed at the corner of carbon fibers in carbon fiber preform. Carbon nanofibers were agglomerated at the corner of carbon fibers, and some were dispersed on the surface of carbon fiber in the hybrid preform. In composites, carbon fibers were homogeneously distributed in the matrix. Further Vickers hardness test results showed that the hardness of carbon fiber reinforced pure Al composite increased by 76% compared to pure Al, and carbon fiber reinforced A336 alloy composite increased by 11.1% compared to A336 alloy. The thermal conductivity (TC) test result illustrated that the thermal conductivity of carbon fiber reinforced pure Al and A336 alloy composite was 245.8W/(m.K) and 113.5W/(m.K), respectively, and the thermal conductivity of carbon fiber-carbon nanofiber reinforced A336 alloy composite was 98.4W/(m.K).