| Stainless steel materials have good mechanical properties and are widely used in various fields.As one of the metal materials with the largest supply and demand,due to the hydrophilicity of the material surface,it is inevitable to cause various damages such as corrosion,pollution or wear in the actual environment,resulting in the reduction of material service life and limited performance,and may also lead to work accidents in serious cases.If the hydrophobic properties of the material surface can be improved,the probability of these situations can be greatly reduced.Therefore,how to improve the surface properties of stainless steel and improve the use value of materials is the focus of current research.In the past,traditional processing methods were mostly used to improve the hydrophobicity of materials.However,with the development of science and technology,all walks of life put forward higher requirements for precision,controllability,convenient process and environmental protection,and the traditional processing can not meet the demand gradually.Femtosecond laser has unique characteristics of non-contact cold machining.It has small thermal damage to materials in the machining process,ensures surface accuracy and quality,and is highly controllable,green and environmental friendly.It can realize micron precision machining and effectively improve the shortcomings of traditional processing technology.Therefore,this paper uses femtosecond laser technology to improve the performance of 304 stainless steel.The main work is as follows:(1)In order to ensure the success of the experiment,the relevant process arrangements were made to improve the surface properties of stainless steel.The experiment is mainly divided into two parts: femtosecond laser processing surface microstructure and silane chemical modification.Combined with the theory,the feasibility and advantages of the experimental design and process flow are clarified.(2)The interaction mechanism between femtosecond laser and materials is studied;An improved two temperature equation based on the light source term is established,and the process and influence of femtosecond laser on 304 stainless steel are numerically simulated and solved;The variation law of material electron and lattice system temperature with laser parameters is summarized,and the reason of small laser thermal damage is explained;Three wetting models are established,two important factors affecting the wettability of materials are explained theoretically,and the feasibility of experimental process design is proved.(3)The specific experiment of femtosecond laser processing stainless steel was carried out.By setting different process parameters,the influence law of different variables on various indexes of surface microstructure in single factor experiment is studied,and its formation mechanism is analyzed and summarized;The orthogonal experiment was further designed,the matrix array structures with different morphologies were obtained by changing the process parameters,the comprehensive surface processing under multiple factors was studied,and the effects of various factors on the depth,width and roughness of microstructure were summarized;The range analysis of the results is carried out to determine the most influential processing factors,and the optimal processing level within the set parameters is obtained.(4)Further reduce the surface energy of the materials with microstructure,improve the wettability of the stainless steel surface,and make the contact angle of the material surface reach 150 ° superhydrophobic state;The correlation between microstructure roughness and contact angle in femtosecond laser machining is analyzed;Scanning electron microscope was used to observe the structural morphology characteristics and the overall situation after chemical modification,determine the influence of different morphology on hydrophobic properties,and analyze and summarize the reasons;Finally,the durability,corrosion resistance,self-cleaning and wear resistance of superhydrophobic stainless steel are tested,which shows that the experimental results have certain application value. |
PDF Full Text Request