Highly thermal conductive Csf/Mg composites by in-situ constructing the unidirectional configuration of short carbon fibers

Abstract

Lightweight, low cost, and high thermal conductivity (TC) are crucial targets for thermal management material development. Short carbon fiber reinforced metal matrix composites (MMCs) have attracted extensive attention due to the aforementioned superiorities. Despite compositing short carbon fibers capable of improving the TC of metals to a certain extent, the enhancement efficiency is not satisfactory till now due to the significant anisotropy of fibers. Inspired by the pressure stacking phenomenon of short fibers and using an independently designed preform-forming mold, combined with the Liquid-solid extrusion following vacuum infiltration (LSEVI) technique, we propose a novel technique that could in situ construct the short carbon fiber unidirectional configuration in the AZ91D matrix. According to micro-CT test results and using image processing technology, the high TC of 106.7 W/mK was achieved due to the highly aligned short carbon fibers, which is equivalent to 122.2% enhancement compared to the AZ91D matrix. And the specific TC enhancement efficiency (σ) is significantly higher than that of the prior reports. Furthermore, the short carbon fiber reinforced magnesium (Csf/Mg) composites possess excellent heat conduction capacity compared to the AZ91D magnesium alloy, according to the thermal management capability test experiment. Our results not only chalk up a record value σ for short carbon fiber reinforced MMCs, but also provide a road map for future employing the Csf/Mg composites in the field of thermal management.