超疏水镍钴氮化硅涂层表面微织构演化规律及其摩擦磨损性能研究OA

The surface texture has well-known anti-friction benefits,yet the effect of superhydrophobic coating texture morphology on friction and wear properties remains insufficiently explored.The electrodeposition has high mass transfer efficiency and fast deposition speed.Laser processing of surface micro texture has high processing efficiency,high precision,and little environmental pollution.The combination of electrodeposition technology and laser texturing technology is conducive to tapping each other's technical potentials.The environmentally friendly coatings are developed and designed,which realizes the quick development of special functional coating surfaces and meets the high requirements of modern industrial and agricultural production.In this study,Ni-Co-Si3N4 nanocomposite coatings were prepared by electrodeposition and microtextures were subsequently fabricated on the coating surface with laser surface texturing technology.The surface morphology,elemental distribution,chemical composition,roughness,static contact angle,friction coefficient and wear cross-sectional area of the laser-textured coating were examined.Through optical contact angle measurements and tribological testing,the wettability and wear resistance of the textured coating were investigated to elucidate the combined mechanism of superhydrophobicity and tribological behavior.The results showed that the microstructure of the irradiated region evolved into convex and concave features at varying laser pulse energy densities and pulse widths.In addition,a convex dome was formed on the coating surface at a low laser output power and a suitable pulse width,while a dimple was formed on the coating surface at a high pulse energy density.Four distinct textures,including W-shaped pits,shallow pits,deep pits,and pits with double concentric holes,were successfully produced under optimized laser parameters.The laser-textured coating surfaces were dense and continuous,with no observable cracks or pores.However,the surface roughness and static contact angle increased significantly,enabling the Ni-Co-Si3N4 composite coating to attain superhydrophobic characteristics.After laser texturing,the oxygen content of the Ni-Co-Si3N4 composite coating increased significantly,which was attributed to oxidation caused by elevated temperatures in the irradiated zone.Dimples formed near the laser spot center when local temperatures approached the melting point of the coating.Laser texturing improved hydrophobicity by enhancing the surface roughness(Sa)of the Ni-Co-Si3N4 composite coating.Compared to the other three textures(TW,TS,and TA),the TD texture exhibited the greatest surface roughness(1.624 µm)and the highest static contact angle(155.3°),achieving excellent superhydrophobic performance.Based on the Wenzel-Cassie's model,the air-fraction occupancy at the liquid-solid interface reached 91.9%.Moreover,the Ni-Co-Si3N4 composite coating after laser processing exhibited a higher microhardness,higher wear resistance,and improved wettability compared to those of the normal coatings.Tribological tests revealed that the microtexture significantly improved friction and wear behavior.After laser texturing,the friction coefficients and wear cross-sectional areas decreased,attributable to the ability of appropriately deep dimples to store wear debris and reduce frictional resistance.The textured coating exhibited relatively stable COF values(0.101-0.123)and the laser-textured surfaces exhibited the smallest wear areas.Among the four textures,the TD texture demonstrated the lowest average friction coefficient(0.095)and wear rate(11.01×103 μm3/N·m).This work provides a reference for improving friction and wear properties of superhydrophobic composite coatings based on investigations of Ni-Co-Si3N4 composite coatings with different four distinct textures.Overall,the synergistic effects of superhydrophobicity and surface texturing reduce real contact area,facilitate wear debris capture,minimize abrasive wear and improve frictional smoothness and wear life.