Preparation And Properties Of Bamboo Fiber/Epoxy Resin Composite Friction Material Based On 3D Printing

Direct writing 3D printing technology has gradually been widely used in many fields because of its multi material adaptability,controllable printing process,flexible printing mode and high printing accuracy.The printing ink used in direct writing technology involves a wide variety of materials,among which thermosetting epoxy resin composite is the most widely used in industry because of its light weight,good chemical stability and mechanical properties.Combined with the development trend of environment-friendly materials,the paper prepared bamboo fiber/epoxy resin composites using direct writing 3D printing to explore the application of composites in the field of tribology and to lay the foundation for improving the structural accuracy and comprehensive material performance of 3D printing.The paper prepared thermosetting bamboo fiber/epoxy resin composite friction materials and explored direct-writing 3D printing composites.Firstly,the surface modification of bamboo fibers was carried out to prepare bamboo fiber/epoxy resin composites,based on which graphite and nano-SiO2 were added to improve the friction and wear properties of the composites and to study their wear mechanisms,and finally,the effects of printing parameters such as 3D printing method and filling rate on the friction and wear properties of the composites were investigated.(1)Alkali,silane coupling agent(KH550),alkali,KH550 and diphenylmethane diisocyanate(MDI)had been used to modify the surface of bamboo fiber.The results showed that the epoxy resin composites prepared by alkali/KH550/MDI modified bamboo fiber had better properties.The tensile strength and impact strength of the composites reached the best at 4%bamboo fiber content(0-8%),31.8 MPa and 29.5 kJ/m2,respectively;the friction and wear properties showed that the friction coefficient of the composites decreased first and then increased with the increase of bamboo fiber content,and the lowest at 4%;the wear increased first and then decreased,and the lowest at 6%.(2)Graphite and nano SiO2 were used to modify bamboo fiber/epoxy resin composites respectively.The mechanical properties showed that the addition of graphite(content of 08%)decreased the tensile strength of the composites,but with the increase of graphite content,the tensile strength tended to increase again;the impact strength was optimal at 6%of graphite content.The addition of nano-SiO2(0-4%)decreased the tensile strength of the composites,but the impact strength of the composites showed an increasing trend,and the impact strength was 34.74 kJ/m2 at 2%of nano-SiO2 content,which increased by 18%.It has been found that graphite could improve the wear resistance of bamboo fiber/epoxy resin composites under the friction conditions of 40 N and 50 rpm.Under high speed and high load,nano SiO2 can effectively reduce the friction coefficient and wear rate of the composites.(3)Modified FDM 3D printer to realize direct writing 3D printing,and used direct writing 3D printing technology to print bamboo fiber/epoxy resin composite friction materials.Firstly,equipped with epoxy resin base ink,the effects of printing parameters such as filling rate(40%,50%,80%)and printing mode(line,circle and grid)on printing structure,size and friction and wear properties had been investigated.The research showed that the lines of 3D printing are clearly visible,there was no collapse,and the dimensional accuracy was good.The friction and wear performance test showed that the friction coefficient of the printing material was the smallest when the filling rate is 50%;The friction coefficient was the largest when the filling rate is 80%;Among the three printing methods,the average friction coefficient has little difference,and the wear rate of the line was the largest.Based on this research,bamboo fiber/epoxy resin composite friction material was applied to 3D printing technology.The study on friction and wear properties found that the nano SiO2 modified bamboo fiber/epoxy resin composite had the best friction reduction and wear resistance effect,with a friction coefficient of 0.15 and a wear rate of 4.25*10-6 mm3/N*m,which was better than the composite formed by traditional methods.