Wear Behavior of TiB2–C3N4 Composites Fabricated by SPS Process

Ultra-high-temperature ceramics (UHTCs), particularly titanium diboride (TiB 2 ), are critical for demanding applications such as thermal protection systems, wear-resistant components, and high-temperature applications. However, their strong covalent bonding and poor sinterability pose significant fabrication challenges. This study investigates the incorporation of graphitic carbon nitride (g-C 3 N 4 ) as a sintering aid and reinforcing phase in TiB 2 composites processed via spark plasma sintering (SPS). A TiB 2 -10 wt% g-C 3 N 4 composite was sintered at 1900°C under a pressure of 40 MPa, achieving a relative density of 91.3%. Tribological evaluation via pin-on-disk testing revealed a specific wear rate of 2.455 × 10 −4 mm 3 /N m, approximately half that of monolithic TiB 2 , alongside an estimated hardness of 41.2 GPa. Microstructural analysis identified carbon-rich tribofilms and probably in- situ formed B 4 C nanoparticles as key contributors to enhanced wear resistance. However, the composite exhibited a higher average coefficient of friction (0.67) compared to pure TiB 2 , attributed to less effective lubrication from the tribofilm. These findings demonstrate g-C 3 N 4 as a promising additive for improving the wear performance of TiB 2 -based composites while highlighting the need for further optimization to reduce frictional losses.