Study Of The Fused Deposition Modeling Forming Properties Of Short Carbon Fiber Reinforced Poly-ether-ether-ketone

Polyether ether ketone(PEEK)is a special thermoplastic engineering material with excellent overall performance,whose mechanical properties can be further improved by composited with carbon fiber,which has a wide range of applications in aerospace,automotive industry and medical transplantation.At present,the research of Carbon Fiber Reinforced PEEK is mainly focused on the traditional processes such as hot pressing and injection molding,which are difficult to adapt to the application of highly personalized customization.Fused Deposition Modeling(FDM)is a kind of additive manufacturing process for thermoplastic materials,which can facilitate the rapid prototyping of complex structures and customized products.At present,FDM technology is mainly used for polymer materials with low melting point such as PLA(Polylactic Acid)and ABS(Acrylonitrile Butadiene Styrene plastic).There are few researches on the FDM forming of PEEK materials,especially short carbon fiber(SCF)/ PEEK composites,and the mechanism of the influence of SCF doping and FDM forming process on the properties of SCF/PEEK composites is not clear.In this paper,the FDM forming performance of SCF/PEEK composite is studied,and the influence mechanism of SCF doping concentration,nozzle diameter,nozzle temperature and infill angle on the forming performance of SCF/PEEK is discussed.On this basis,the strength enhancing effect of SCF/PEEK FDM forming is realized.The thesis mainly includes the following two aspects:1)The SCF/PEEK composites with 0%,2% and 5% doping ratio were designed and manufactured.The FDM printing consumables with diameter of 1.75 mm were made by single screw extruder.The thermal properties,interface quality and mechanical properties of the three composites were studied,and the mechanism of the influence of SCF doping concentration on the physical,chemical properties and mechanical properties of SCF/PEEK composites was explored.It is found that the doping of carbon fiber has both positive and negative effects.The doping of SCF can not only enhance the mechanical properties of the composite due to its high strength and high modulus,but also weaken the mechanical properties of the composite by introducing a large number of pores into the composite.The doping of SCF can improve the heat resistance and crystallinity of PEEK resin matrix composite,which has a positive effect on the high temperature durability and mechanical properties of the composite.The doping of SCF results in local stress concentration in the composite,reduces the plastic deformation ability of the composite,and brittle fracture occurs when the composite is subjected to external load.2% SCF doping can enhance the mechanical properties,while 5% SCF doping can weaken the mechanical properties.2)Based on the two factor completely random experimental design method,the FDM forming properties of SCF/PEEK composite was studied.The dopant concentration and nozzle diameter,nozzle temperature,infill angle were used as experimental variables.The tensile properties of the formed samples were taken as the research object.The effects of dopant concentration and corresponding process parameters on the mechanical properties of SCF/PEEK FDM were analyzed.It is found that the nozzle diameter and nozzle temperature have little effect on the FDM forming performance of pure PEEK samples,but with the increase of SCF content,the change of process parameters has more and more obvious effect on the mechanical properties of SCF/PEEK composite FDM parts.The infill angle had the same effect on the mechanical properties of PEEK,SCF/PEEK 2% and SCF/PEEK 5% FDM parts.For SCF/PEEK composites,it is very important to improve the mechanical properties of FDM parts by adjusting the process parameters.Appropriate amount of SCF doping can reduce the damage to the composite interface,the larger nozzle diameter(1.0 mm in this experiment)can reduce the number of fuse joints and effectively improve the interface uniformity of FDM molding parts;appropriate higher nozzle temperature(420°C in this experiment)can improve the melt fluidity of SCF/PEEK composite materials and effectively improve the bonding strength;the filling angle designed along the load direction(0° in this experiment)can form a good stress structure and reduce the content of the third type of pores,which are beneficial to the enhancement of SCF/PEEK's mechanical properties in FDM.