Effect of Cold Rolling on Microstructure and Thermal Conductivity of Carbon Nanofiber Dispersed Copper Matrix Composites

Abstract

Vapor–grown earbon nanofiber (VGCF) was used for the dispersant of pure copper (Cu) matrix composites. As–received VGCF was performed by mixed acid treatment to unravel before powder mixing with Cu particles. Then, 1vol.% and 2vol.% VGCF/Al composites were fabricated by spark plasma sintering (SPS). But re–formation of VGCF aggregates was formed in sintering, and small–sized aggregated VGCF was distributed in composites. By using cold–rolling, aggregated VGCF was stretched along the rolling direction, but it was difficult to control the direction more finely due to the complexity of the entangled. The cracks were introduced by the increase of the rolling rate. The generation of cracks could be suppressed by adding an annealing process during rolling. With the increase in rolling rate, once the thermal conductivity improved but then decreased. The improvement in thermal conductivity seems to be due to the improvement of the orientation of the agglomerated VGCF in the rolling direction. The decrease is thought to be caused by the introduction of cracks, work hardening, etc.