Study On Microstructure And Wettability Of Glass Surface By Picosecond Laser Machining

Glass is a kind of transparent material with high hardness,high brittleness and high transmittance,which has good thermal and electrical properties and is widely used in many kinds of industries.It is also due to these properties that traditional mechanical processing methods can no longer be adequate to satisfy the requirements for precision processing of glass surface.While laser machining has the advantages of simple operation,high speeds and no pollution,which make laser micromachining a promising technology for ultra-precision processing.In this thesis,a superhydrophobic glass surface with high adhesion is prepared based on the basic theory of interaction between laser and material and technology of picosecond laser machining,combined with the method of chemical modification by low surface energy material.The effects of different laser parameters on surface morphology,surface wettability and surface adhesion of glass surface are investigated,and the surface abrasion resistance experiments are conducted.The possibility of application on droplet transport using superhydrophobic glass surface with high adhesion is briefly discussed.The main contents of this thesis are as follows:(1)Basic theory of interactions between picosecond laser and glass material.Based on the laser absorption mechanism of glass material,the calculation equation of the absorption rate of glass surface is derived,and the effects of the laser incident angle and the refractive index of glass on the absorption rate of glass surface are investigated.Based on the extrapolation method,the circular pits are created on glass surface using different laser pulse energies,and the ablation threshold of glass material is calculated as 1.739 J/cm~2 by linear fitting.Based on the phenomenon of interaction between laser and material,the generation threshold of plasma is derived,the energy density distribution of plasma induced with different laser energies is simulated,and the micromachining processing of materials by plasma is studied.(2)Comparative study of direct laser ablation and laser induced plasma assisted ablation for the fabrication of single-channel microgrooves on glass surfaces.Direct laser ablation and laser induced plasma assisted ablation are separately utilized to ablate microgroove structures on glass surfaces.The differences in surface morphology of glass surface ablated by two laser processing methods are studied.The effects of different laser parameters on surface morphology of glass surface are investigated.The differences in chemical composition of glass surface after direct laser ablation and laser induced plasma assisted ablation are compared.The results show that the microgroove structure ablated by direct laser ablation is larger in size and suitable for subsequent experiments.(3)Preparation and property characterization of superhydrophobic glass surfaces with high adhesion.The superhydrophobic glass surface with high adhesion is prepared by direct laser ablation to fabricate grid microstructures on glass surface for roughening treatment and chemical modification with low surface energy material on roughened glass surface.The effects of different laser parameters on surface morphology,surface wettability and surface adhesion of glass surfaces are investigated,and abrasion resistance tests are performed.