Silicon carbide (SiC)-zirconium diboride (ZrB2) composites are produced by subjecting a 60 : 40 vol% mixture of β-SiC powder and ZrB2 matrix to spark plasma sintering (SPS). Sintering is carried out for 60 sec at temperatures of 1400 oC and 1500 oC and uniaxial pressures of 40 MPa, 50MPa, and 60 MPa, under argon atmosphere. The physical, mechanical, and electrical properties of the sintered SiC-ZrB2 composites are examined. Evidence of reactions between β-SiC and ZrB2 in the SiC-ZrB2 composites sintered under argon atmosphere is not observed by high-resolution x-ray diffraction (HR-XRD) analysis. The trends in the apparent density and flexural strength of the sintered SiC-ZrB2 composites are not dependent on the uniaxial pressure when the sintering temperature is 1500 oC. Among the sintered SiC-ZrB2 composites, the specimen produced at 1500 oC and 50 MPa shows the lowest volume electrical resistivity at room temperature, 0.617 × 10-3Ω·cm. By energy-dispersive spectroscopy (EDS) mapping, it is confirmed that ZrB2-chain formation in the sintered SiC-ZrB2 composites uniformly occurred at 1500 oC and 50 MPa. The flexural strength of the sintered SiC-ZrB2 composites is dependent upon their apparent density, but the volume electrical resistivity is independent of the apparent density. Densification of a sintered SiCZrB2 composite through hot pressing is dependent on the sintering temperature and pressure. However, this study confirms that the densification of SiC-ZrB2 composites through SPS does not depend on the uniaxial pressure.

Keywords: Spark plasma sintering (SPS), Uniaxial pressure, Positive temperature coefficient resistance (PCTR), Sintering temperature.