Theory And Process Research Of Recycling Carbon Fiber Reinforced Composites By Laser

Carbon fiber reinforced plastics(CFRP)is an essential strategic material,which has been widely used in industry and defense fields.With the gradual expansion of application fields,carbon fiber recycling and the reuse technology of CFRP waste is on the agenda.At present,the main recycling methods for carbon fibers include mechanical recycling,chemical solvent recycling,and thermal decomposition recycling.However,the above-mentioned recycling methods have problems such as complex,cumbersome recycling processes and easy damage to carbon fibers,so it is urgent to explore new carbon fiber recycling methods and processes.The interaction between laser and material is highly controllable and has potential application prospects in the field of carbon fiber recycling.This paper combines numerical simulation and experiment to study the basic theory and process method of recycling CFRP by laser.The main research contents and conclusions are as follows:(1)Numerical simulation research of recycling CFRP by laser.The two-phase twodimensional models of 355 nm nanosecond and 1064 nm picosecond lasers on CFRP were established with the help of ANSYS finite element software to study the effects of wavelength,scanning speed and average power on the laser recovery of CFRP.The results show that during the ablation of CFRP by two kinds of wavelength lasers,with the increase of the number of pulses,the temperature growth rate of the fiber surface gradually becomes flat.When two kinds of wavelength lasers are used to recycle fibers,the laser scanning speed increases with the increase of laser power,and the range of scanning speed decreases continuously with the increase of power.1064 nm nanosecond laser has more advantages than 355 nm picosecond laser in recycling carbon fiber,and has a wider range of recycling parameters.(2)Optimization process parameters research of recycling CFRP by laser.Scanning ablation experiments were carried out on CFRP with a laser,and the ablation depth and surface conditions of the CFRP cross section after laser ablation were observed with a scanning electron microscope,and the process conditions for recovering surface fibers were analyzed.The results show that at the same power,with the increase of scanning speed,the ablation depths of the two kinds of wavelength lasers on CFRP gradually decrease,and the surface of CFRP gradually changes from fiber fracture to resin residue;when the scanning speed is fixed,the increase in power increases the ablation depth.When two wavelengths of laser are used to recycle fibers,the laser scanning speed increases with the increase of power,and the range of scanning speed decreases with the increase of power.Compared with the 1064 nm nanosecond laser,the 355 nm picosecond laser requires a lower scanning speed for recycling materials,and its optimal recycling speed range is narrower.In practical applications,it is more difficult to use picosecond laser recycling.The main experimental rules are consistent with the simulation results.(3)Product performance analysis of recycling CFRP by laser.The surface morphology,organizational structure and mechanical properties of the recovered carbon fiber filaments were tested,the factors affecting the mechanical properties and morphology of carbon fibers were analyzed,and the process parameters were comprehensively evaluated and optimized.The results show that increasing the scanning speed will lead to the weakening of the degree of graphitization on the fiber surface,and when the speed reaches the edge of the parameter interval,there will be obvious resin residue on the surface.The fiber roughness recovered by infrared nanosecond laser is 120～131 nm,and there is a small amount of resin particles on the surface of the sample with the highest roughness;the carbon fiber recovered by ultraviolet picosecond laser has a roughness of117～125 nm,and there is no resin residue on the surface under the highest roughness.According to Raman detection,the D peak and G peak of recycled fiber have obvious peak separation phenomenon,and they all have different degrees of graphitization,and the degree of graphitization of recycled fiber by ultraviolet laser is more serious than that of nanosecond laser.The tensile strength of carbon fiber recycled by infrared nanosecond laser is about 66%～83% of that of the original silk,which exceeds the mechanical recycling method and most of the thermal decomposition recycling methods,and the tensile modulus is increased by 1%～12%;the tensile strength of ultraviolet picosecond laser fiber is about 58%～75% of the original silk,and the tensile modulus is increased by 6%～14%,which is at the same level as most thermal decomposition recycling methods.Combining multiple characterization results and considering the economic cost,the infrared nanosecond laser can recover carbon fibers with no resin residue,high roughness and excellent mechanical properties within the optimal parameter range.