Effects of adding GPLs dispersed at different sonication times on the thermal and electrical conductivities of spark plasma sintered silicon carbide

Abstract

This study has investigated the effects of adding 1 wt % graphene platelets (GPLs) dispersed at different probe-sonication times such as 1, 2, 4 and 6 h on the microstructure, thermal and electrical conductivities of the spark plasma sintered (SPSed) silicon carbide (SiC) matrix. According to scanning electron microscope (SEM), size measurement and Raman analyses, the dispersion of the GPLs increased, the platelet sizes decreased, and the defect concentrations on the structure of GPLs increased as the sonication time increased. While the size reduction was only around 2–5% up to 2 h sonication time, it increased to 25–30% at the 4 and 6 h sonication times. 2 h sonicated GPLs provided the highest contribution among all GPLs, increasing the thermal and electrical conductivity of the SiC matrix by 24 % and ∼106 times, respectively due to having a combination of large lateral size, good dispersion, and low defect concentration characteristics. Anisotropic effect on thermal and electrical conductivities of GPLs-SiC composites decreased with increasing probe-sonication time since the reduction in platelet size of GPLs led to a decrease in their orientation degree within the matrix microstructure.