Enhanced Toughness and Wear Resistance in CoO-Doped Si3N4 Ceramics via Spark Plasma Sintering

In this study, CoO was used as a toughening phase to fabricate CoO-doped Si 3 N 4 ceramics by spark plasma sintering. The effects of different temperatures (1700°C, 1750°C,1800°C,1850°C) and CoO contents(0 wt%, 5 wt%, 10 wt%, 15 wt%) on the phase composition, microstructure, mechanical properties, and tribological properties of Si 3 N 4 ceramics were systematically investigated. The X-ray diffraction analysis revealed the formation of a new phase CoSi during the sintering process. Experimental results showed that the samples with 10 wt% CoO resulted in a 30% increase in the fracture toughness of the samples at a sintering temperature of 1700°C. Furthermore, at a sintering temperature of 1750°C, 5 wt% CoO increased the hardness by 12% and 10 wt% CoO increased the flexural strength by 51%. The doping of CoO improves the wear resistance of the material, and wear rate reduced by 71% compared to undoped CoO. Finally, first-principles calculations confirmed the interface stability of Si 3 N 4 -CoSi heterojunction. This study provides a new technological path for the development of Si 3 N 4 ceramic bearing materials with high toughness and excellent wear resistance.