Study On Liquid-Phase Assisted Laser Preparation And Friction Properties Of Surface Texture

Surface texture technology can significantly improve the wetting and friction properties of workpiece surfaces,which has been paid attention to and applied in the field of mechanical engineering by scholars both domestically and internationally.304 stainless steel is widely used in mechanical components due to its excellent mechanical and corrosion resistance.In order to improve the wettability,corrosion resistance,and tribological properties of 304 stainless steel,this study combines liquid-phase assisted machining technology with laser surface texture preparation.The negative pressure impact effect,interface attenuation effect,and scattering effect generated by the interaction between the high-energy laser beam and the solution substrate have been utilized to reduce the regional thermal effect,melt recasting,and burrs during laser preparation of surface texture,and improve the processing quality and efficiency.In addition,by changing the laser scanning trajectory,a three-dimensional discrete surface texture was prepared on the surface of the sample,increasing the diversity of texture surface morphology,thereby improving the wettability,corrosion resistance,and friction characteristics of the 304 stainless steel surface.The main research content of this paper is as follows:Firstly,the material properties of 304 stainless steel and the influence of rainwater corrosion were described.The performance comparison experiments of 304 stainless steel before and after rainwater corrosion were carried out,and the surface morphology,wettability and tribological properties of 304 stainless steel before and after rainwater corrosion were obtained.Secondly,the laser surface texture preparation and liquid phase assisted processing technology are combined to explore the liquid phase assisted mechanism and laser processing parameters,and then a three-dimensional discrete surface texture with better surface morphology,wettability and friction performance is prepared on the surface of 304 stainless steel.Then,four different types of surface textures(KY,YY,KJ and YJ)were prepared on the surface of 304 stainless steel by circular and cross laser scanning under air and liquid assisted conditions.The surface morphology and element content of the samples were measured by SEM and EDS.The wettability of the sample surface was characterized by a contact angle measuring instrument.The tribological tests were carried out using a MWF-500 reciprocating friction and wear tester under dry friction and oil lubrication conditions.The results show that under the assistance of liquid phase,the surface of the sample generates a wave-like microstructure texture,which enhances the surface wettability.In particular,the surface texture prepared by cross-scanning has a more uniform distribution of micro-pits,which is easier to capture wear particles,thereby reducing the number of interfacial wear particles and showing better interfacial tribological properties.Finally,the preparation of air-liquid composite laser texture was studied,and two kinds of surface textures(CM2 and CM5)with scanning intervals of 0.02 mm and 0.05 mm were prepared.The results show that the surface texture prepared by air-liquid phase composite laser presents hydrophobic characteristics as a whole,which improves the corrosion resistance of 304 stainless steel surface.However,compared with CM2 sample,the laser scanning spacing of CM5 sample is too large,and the laser processing is not sufficient,resulting in poor surface uniformity and hydrophobicity of CM5 sample.The surface morphology of CM2 sample is evenly distributed without large micro.