Effect of fishbone variable-depth surface texturing on the friction and wear performance of silicon carbide under water lubrication

Abstract Surface textures significantly improve the tribological properties of friction pairs by optimising the selection of texture types and structural parameters, thereby enhancing antiwear and friction-reducing performance. In this study, to enhance the tribological performance of silicon carbide (SiC) planar friction pairs, a fishbone variable-depth reticular texture was developed through the computational fluid dynamics (CFD) optimisation of a cross-reticular texture. Its lubrication and friction-reducing capabilities were then validated via tribological experiments, and advanced characterisation techniques were used to elucidate its underlying mechanisms. Experimental results demonstrate that the fishbone texture significantly lowers the interfacial coefficient of friction (COF) during counterclockwise rotation, especially at speeds exceeding 1200 rpm, where the COF drops below 0.01, achieving superlubricity. Frictional heat tests indicate that the fishbone texture effectively mitigates the temperature rise in friction pairs. Interfacial frictional electric tests reveal that the fishbone texture enhances the interfacial polarisation electric field, thereby improving the adsorption capacity of lubricant films and increasing the electric field repulsion between friction pairs. The lubrication and friction-reducing mechanisms of the fishbone texture are governed by four synergistic effects: the variable-depth area of the pressurisation unit enhances the hydrodynamic effect; the wedge area induces a secondary throttling effect; a shear-easy silicon-based friction film forms during interfacial friction; and the polarisation electric field generated by the solid-liquid-solid interfacial friction creates repulsive forces. This study presents a novel strategy for improving the lubrication and friction-reducing performance of high-speed, heavy-load bearings, providing significant theoretical and practical contributions.