Preparation of ZrB₂-SiC composites by arc melting and their properties

Abstract

ZrB₂-SiC composites were prepared by arc melting using ZrB₂ and β-SiC powders as raw materials and their Vickers micro-hardness, electrical conductivity and thermal conductivity were investigated. The eutectic composition of the ZrB₂-SiC system was ZrB₂-58.5 mol%SiC with a labyrinthine microstructure 100 nm in width and several μm in length. The hardness of the ZrB₂-SiC composites increased with increasing SiC content and showed the highest value of 24 GPa at an indenter load of 4.9 N around the eutectic composition. The ZrB₂-SiC eutectic composite had the highest fracture hardness of 6 MPa m^1/2. The electrical conductivity of ZrB₂-SiC composites ranged from 3.2×10⁴ to 5.0×10⁶ S m^-1 at room temperature and decreased with increasing temperature. Their thermal conductivity at room temperature was 70 to 95 W m^-1 K^-1 and decreased with increasing temperature. The eutectic composite had the lowest thermal conductivity.