High-entropy carbide (NbTaTiV)C₄ (HEC4), (MoNbTaTiV)C₅ (HEC5), and (MoNbTaTiV)C₅-SiC (HEC5S) multiphase ceramics were prepared by spark plasma sintering (SPS) at 1900 to 2100 °C, using metal carbide and silicon carbide (SiC) as raw materials. Their microstructure, and mechanical and tribological properties were investigated. The results showed that the (MoNbTaTiV)C₅ synthesized at 1900–2100 °C had a face-centered cubic structure and density higher than 95.6%. The increase in sintering temperature was conducive to the promotion of densification, growth of grains, and diffusion of metal elements. The introduction of SiC helped to promote densification but weakened the strength of the grain boundaries. The average specific wear rates for HEC4 were within an order of magnitude of 10⁻⁵ mm³/N·m, and for HEC5 and HEC5S were within a range of 10⁻⁷ to 10⁻⁶ mm³/N·m. The wear mechanism of HEC4 was abrasion, while that of HEC5 and HEC5S was mainly oxidation wear.

SiC multiphase ceramics were prepared via spark plasma sintering using AlN and TiB₂ as the second phase and Y₂O₃ as a sintering additive. The effects of TiB₂ content (10 vol.% and 20 vol.%) and sintering temperature (1900 °C to 2100 °C) on the phase composition, microstructure, and mechanical and tribological properties of SiC multiphase ceramics were investigated. The results showed that Y₂O₃ reacts with Al₂O₃ on the surface of AlN to form the intercrystalline phase Y₄Al₂O₉ (YAM), which promotes the densification of the multiphase ceramics. The highest density of SiC multiphase ceramics was achieved at 10 vol.% TiB₂ content. Moreover, TiB₂ and SiC exhibited good interfacial compatibility. In turn, a thin solid-solution layer (~50 nm) was formed by SiC and AlN at the interface. The periodic structure of SiC prevented the dislocation movement and inhibited the base plane slip. The most optimal mechanic characteristics (a density of 98.3%, hardness of 28 GPa, fracture toughness of 5.7 MPa·m^1/2, and bending strength of 553 MPa) were attained at the TiB₂ content of 10 vol.%. The specific wear rates of SiC multiphase ceramics were (4–8) × 10⁻⁵ mm³/N·m at 25 °C and 2.5 × 10⁻⁵ mm³/N·m at 600 °C. The wear mechanism changed from abrasion at 25 °C to a tribo-chemical reaction at 600 °C. Therefore, adding lubricious oxides of TiB₂ is beneficial for the improvement in wear resistance of SiC ceramics at 600 °C.