Experimental studies of friction and wear on textured surfaces filled with composite solid lubricant and lubricated with grease were conducted on a sliding plain bearing to enhance the working performance and lifetime under different conditions. Circular microdimples of different diameters were fabricated on GCr15 bearing steel specimens using the semiconductor sound and light pumped Nd:YAG laser machining equipment. Ring-on-ring tribological test configuration with GCr15 tribopairs under a combined non-Newtonian lubrication of grease and composite lubricant was performed. The results showed that the surface textures on specimen GCr15 bearing steel material filled composite solid lubricant and lubricated with grease (TLG), reduced the friction by 27%, 46%, and 75% of the grease only (TG), solid lubricant only (TL), and nonlubricated (T) specimens, respectively. The textured specimen with dimple diameter of 109 μm lowered the maximum coefficient of friction by 38% and enhanced the antiwear properties of GCr15 bearing steel material remarkably. This indicated that grease has great potential in promoting service life and working performance of sliding plain bearing when combined with composite solid lubricant in a laser-textured surface. It is therefore beneficial for applications in the machinery and automotive components industries in saving energy and reducing CO2 emission.

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There is comprehensive work on the tribological properties and lubrication mechanisms of oil lubricant used on textured surfaces, however the use of grease lubrication on textured surfaces is rather new. This research article presents an experimental study of the frictional behaviours of grease lubricated sliding contact under mixed lubrication conditions. The influences of surface texture parameters on the frictional properties were investigated using a disc-on-ring tribometer. The results showed that the friction coefficient is largely dependent on texture parameters, with higher and lower texture density resulting in a higher friction coefficient at a fixed texture depth. The sample with texture density of 15% and texture depth of 19 µm exhibited the best friction properties in all experimental conditions because it can store more grease and trap wear debris. The reduction of friction is mainly attributable to the formation of a stable grease lubrication film composed of oil film, transfer film and deposited film, and the hydrodynamic pressure effect of the surface texture, which increases the mating gap and reduces the probability of asperity contact. This result will help in understanding the tribological behaviour of grease on a textured surface and in predicting the lubrication conditions of sliding bearings for better operation in any machinery.

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