Effect of graphene nanoplatelets content on electrical and thermal conductivity of pressureless-sintered SiC ceramics

SiC/GNPs composites with high thermal conductivity and low resistivity were fabricated with graphene nanoplatelets (GNP) as additive by pressureless solid-state-sintering at 2200 °C. The effects of GNPs content and annealing process on the microstructure and properties of the SiC/GNPs composites were investigated. As the GNPs content increased from 0 to 3 wt%, the flexural strength, thermal conductivity, and resistivity of the SiC/GNPs composites correspondingly decreased. Compared to SiC ceramics without GNPs, the resistivity of the SiC/GNPs composites with 3 wt% GNPs content markedly decreases, from 10 8 to 6.18 × 10 2  Ω cm, while the thermal conductivity slowly drops from 144.2 to 117.8 W/(m·K). Additionally, the influence of annealing atmosphere on the electrical and thermal behavior of the composites was also examined. Annealing under argon resulted in increased thermal conductivity and decreased resistivity. When annealed in a nitrogen, the resistivity of the samples decreases significantly from 618 to 181 Ω cm, while causing only a slight decline in thermal conductivity. These findings highlight the benefits of argon annealing for enhancing the overall electrothermal performance of SiC/GNPs composites.