Preparation and Thermal Conductivity of Spark Plasma Sintered Aluminum Matrix Composites Reinforced with Titanium-Coated Graphite Fibers

Short graphite fiber/Al composites are fabricated by spark plasma sintering technique. A titanium coating synthesized on the graphite fiber surface through vacuum microdeposition is proposed to improve the interfacial bonding between graphite fibers and aluminum matrix. The influences of surface modification, sintering temperature, and graphite fiber volume fraction on relative density and thermal conductivity (TC) of the composites are systematically investigated. The results indicate that compared to uncoated graphite fiber/Al composites, the densification, interfacial bonding, and TC of titanium-coated composites are greatly enhanced. The in-plane TC of 50 vol% titanium-coated graphite fiber/Al composites sintered at 610 degrees C is 238Wm(-1)K(-1), nearly twice as high as that of uncoated composites. From the calculation based on the experimental TC by Maxwell-Garnett effective medium approach, the interfacial thermal resistance is evidently decreased by above 1 order of magnitude with the introduction of titanium nanolayer.