Research On Laser Transmission Welding Of Polyarylsulfone Based On Zinc Powder Absorbent

Laser transmission welding technology is widely used in many areas due to its advantages such as high welding quality,high processing efficiency,clean welding seam morphology,and small thermal stress.According to the requirements of different industrial applications,the choice of polymer types needs further expansion.The absorbent necessary for LTW can meet the requirements in actual production but is difficult to apply on a large scale,so it needs to be explored in depth.This paper takes the high temperature resistant polymer polyarylsulfone(PASF)as the research object,and proposes a welding method of slotting and filling zinc powder absorbent on the surface of the absorption layer of PASF.The effect of zinc powder absorbent on the welding quality of laser transmission welding PASF was investigated.By comparing welding experiments,the welding quality change laws and the welding joint connection mechanism when using zinc powder absorbent was analyzed.A mathematical analysis model between different welding process parameters with welding strength and weld width was established.Welding process parameters were optimized for different goals.A 3-D transient finite element model based on zinc powder absorbent was constructed,and the temperature and flow fields were numerically simulated.The research content is as follows:Firstly,the interaction between laser and polymer during LTW and the transformation of laser energy converted into thermal energy and conducted in the polymer were explored.A temperature prediction model along the depth of the molten pool without a separate absorbing layer was established,and it was further expanded into a temperature prediction model considering the presence of zinc powder absorbent.The interaction between the zinc powder particles and the laser beam in the molten zone was studied.A rapid melting and solidification model was constructed.Secondly,two methods,zinc powder absorbent and carbon black absorbent,were used for comparative experiments.Comparative analysis found that the welding strength which used zinc powder absorbent was slightly lower than that used carbon black absorbent,but the weld width was significantly smaller than that used carbon black absorbent.The effects of different welding process parameters(welding speed,laser power and zinc powder absorbent level)on welding strength and weld width were studied through single-factor experiments.By observing the macro and micro morphology of the weld and cross section,the fracture mode of the joint was investigated.It was found the mosaic structure between the metal powder and the polymer and the intermolecular forces of the polymer were beneficial to the welding quality.The mutual attractive connection reaction between the molten zinc powder particles and the polymer molecular chain was further researched.The chemical reaction between the zinc powder absorbent and the polymer was investigated by EDS and XPS.It was found that a new chemical bond,Zn-C,facilitated the joint connection.Thirdly,a three-factor five-level experimental scheme was planned using CCRD.A mathematical analysis model between three welding process parameters(laser power,welding speed and zinc powder absorbent level)with welding strength and weld width was established by RSM.The impact trends and interactions between these parameters on welding strength and weld width were analyzed.According to different optimization goals,the best combination of welding process parameters was obtained.The model's accuracy was verified by selecting random welding parameters for experiments.Finally,a 3-D transient model of laser transmission welding PASF based on zinc powder absorbent was constructed.The temperature and flow fields were numerically simulated.The change laws of temperature and flow field with time were obtained.The effects of three parameters(laser power,welding speed and zinc powder absorbent level)on the simulation results of both were explored.This paper selects the high temperature resistant polymer PASF and proposes a welding method for slotting and filling zinc powder absorbent.Thus,the types of polymers in LTW technology were widened,and LTW of double transparent polymers was realized,which offered theoretical support and technical guidance to the practical industrial production applications.