Research On Laser Welding Technology Based On Cryogenic Glass Frit

Transparent material welding is a new direction for laser welding of non-metallic materials,and laser welding technology for glass has become a research hotspot in intelligent manufacturing,new energy and other application fields.This paper is based on the sealing welding requirements of glass plates and conducts basic research on glass laser welding technology using near-infrared fiber lasers.Due to the characteristics of glass,such as fragility,high hardness,high melting point,low thermal conductivity,and high transmittance in the visible light band,it is difficult to use ordinary mechanical and thermal methods for welding.This paper adopts advanced fiber laser technology and combines low-temperature glass solder to weld high borosilicate glass plates.The temperature and stress distribution characteristics of the welding process are simulated using finite element method,and the influence of welding process parameters on welding quality is experimentally explored.The parameters are optimized to avoid defects such as cracks and pores.The main research work of this paper includes the following aspects:（1）Analyzed the working principle of low-temperature glass laser welding,including the properties of low-temperature glass solder,the process of low-temperature glass laser welding,the typical coupling behavior analysis between glass substrate and glass solder,and the key factors of low-temperature glass laser welding,providing a corresponding theoretical basis for the research project;Secondly,a fiber laser welding system was designed and constructed,with high borosilicate glass and low-temperature glass frit Koartan 5643W selected as the experimental research objects,and a pre-treatment process was carried out to provide an experimental basis for low-temperature glass frit laser welding.（2）A transient temperature field model of laser welding was established using the finite element analysis software Ansys Workbench.Based on thermal stress coupling,the temperature and stress fields were simulated to obtain the changes in the spatial temperature field during the welding and cooling processes,the impact of different welding parameters on the temperature field,and the parameter regions for low-temperature welding were defined.At the same time,the stress distribution during the welding process was studied to obtain the characteristics of stress changes.The final test results verify that the model is reliable.（3）Using a single factor method to analyze the influence and characteristics of laser power,welding speed,glass thickness,and frit thickness on cracks and pores.This paper proposes methods to reduce the length of solder and designs specialized heat treatment fixtures to effectively solve the problem of welding thermal stress.Secondly,the process parameters were optimized to achieve a weld morphology without cracks and pores.The optimal welding process parameters were obtained as follows:laser power of 100 W,welding speed of 0.5mm·s^-1,spot diameter of 2 mm,glass substrate thickness of 3 mm,and frit thickness of 30μm.The preheating temperature is 250℃,and the insulation time is 20 minutes.（4）Use welding quality inspection to evaluate the quality of welding performance.Capture and analyze the morphology characteristics of the weld seam through metallographic microscopy and SEM（Scanning Electron Microscopy）;Through EDS（Energy Dispersive Spectrometer）testing,it was found that the unique Pb elements in the solder and Na elements in the glass migrate towards the bonding layer,which is beneficial for improving the bonding performance;Through XRD（X-ray diffraction）testing results,it was found that there was no crystal precipitation under the optimal parameter conditions,indicating complete vitrification and sufficient melting of the solder;By improving the roughness of the glass surface,the maximum improvement in shear mechanical properties is 76%.