Tribological behavior of SiC/Si composites fabricated by vat photopolymerization

Silicon carbide/silicon (SiC/Si) composites are widely used in mechanical seals and water-lubricated bearings because of their outstanding mechanical, chemical and physical properties. Vat photopolymerization (VP) offers a new route for fabricating geometrically complex parts; nevertheless, the friction-and-wear mechanisms of SiC/Si composites produced by this technique remain unclear. To address this knowledge gap, we fabricated SiC/Si composites by VP followed by liquid silicon infiltration (LSI) and systematically tuned the content of fine SiC particles and the solid loading of the suspension to optimise tribological performance. The best-performing composite (denoted as T7, with a solid content of 40 vol% and a fine SiC ratio of 20 wt%) was subsequently tested against Al₂O₃, SiC and Si₃N₄ under both dry and water-lubricated conditions, and the corresponding wear mechanisms were elucidated. Under dry sliding, a self-lubricating tribofilm formed in situ at the T7/SiC interface, reducing the friction coefficient and wear rate to 0.27 and 2.54 × 10⁻⁵ mm³N⁻¹m⁻¹ , respectively. Water lubrication further decreased these values to 0.17 and 0.53 × 10⁻⁵ mm³N⁻¹m⁻¹ when T7 was paired with Al₂O₃, because hydrolysis between the friction pair is largely suppressed. At 700 °C, accelerated wear of the T7/SiC couple was observed and is attributed to the synergistic action of mechanical rubbing and oxidative attack. • Fine SiC content and solid load optimization enhance SiC/Si composite tribology. • In-situ self-lubricating films form on SiC/Si composites and SiC, reducing wear. • Weaker hydrolysis with Al₂O₃ than SiC and Si₃N₄ leads to less wear in SiC/Si. • 700°C tribo-oxidation synergistically accelerates Si-SiC oxidation and wear. • VP-LSI prepared SiC/Si composites show superior wear resistance over traditional ones.