Thermal and Electrical Properties of (Cr,Mo,Ta,V,W)C High-Entropy Carbide Ceramics

Abstract: The synthesis and characterization, along with the resulting properties, of fully dense ((\mathrm{Cr, Mo, Ta, V, W})\mathrm{C}) high-entropy carbide ceramics were studied. The ceramics were synthesized from metal oxide and carbon powders by carbothermal reduction, followed by spark plasma sintering at various temperatures for densification. Increasing the densification temperature resulted in grain growth and an increase in the lattice parameter. Thermal diffusivity increased linearly with testing temperature, resulting in thermal conductivity values ranging from approximately (7~\mathrm{W\,m^{-1}\,K^{-1}}) at room temperature to (12~\mathrm{W\,m^{-1}\,K^{-1}}) at (200~^\circ\mathrm{C}). Measured heat capacity values matched theoretical estimates made using the Neumann--Kopp rule. Room-temperature electrical resistivity decreased from (137) to (120~\mu\Omega\cdot\mathrm{cm}) as the excess carbon decreased from (5.4) to (0.1~\mathrm{vol\%}), suggesting an enhanced electronic contribution to thermal conductivity as excess carbon decreased. All specimens exhibited a Vickers hardness of approximately (29~\mathrm{GPa}) under a (0.49~\mathrm{N}) load. These results underscore the tunability of this high-entropy carbide system.