Preparation and properties of a new type of water-lubricated composite material with porous ceramic skeleton

Under boundary lubrication conditions, the instability of the water film causes severe wear in water-lubricated bearing friction pairs. To address the poor wear resistance of polymer materials for water-lubricated bearings, this study utilized freeze-casting technology to fabricate a porous silicon nitride skeleton and introduced polyurethane via vacuum impregnation, successfully preparing a silicon nitride/polyurethane water-lubricated ceramic composite. The effects of slurry solid content on the porous structure of silicon nitride and the composite's properties were investigated. The results demonstrate that solid content influences the number of ice crystal layers, thereby affecting pore spacing and wall thickness. The introduced polyurethane forms a soft-hard structure with the porous silicon nitride skeleton, providing storage capacity and wear resistance. Additionally, due to its damping and lubricating effects, polyurethane significantly reduces friction-induced vibration and the friction coefficient of the composite. The synergistic effects of these factors markedly improve the tribological performance of the composite. Under a 10 N load, the composite exhibits a 68.7 % and 76 % reduction in friction coefficient compared to pure polyurethane and industrial silicon nitride, respectively, with wear amounts decreased by 96 % and 63.3 %.