Preparation And Properties Of Fiber Reinforced Aluminum Matrix Biomimetic Composites Through 3D Printing

Since ancient times,"attack and defense integration"is the core concept of strategists.The defense system is an indispensable part of the group,the small team and the individual.After billions of years of evolution,many organisms in nature have grown ingenious macro/microstructures for self-protection for their own survival needs.Interestingly,scholars have found that many biological tissues have evolved the same microstructure,such as the wing sheath of the beetle,the chelates of shrimp and crab,and the hierarchical fiber helix.This structure gives the"armor"of creatures such as beetles,shrimp and crabs a lighter and higher strength to prevent natural enemy attacks.In this paper,the hierarchical spiral structure of organisms is selected as the model for bionic structure design,and the materials are assembled in order to prepare fiber reinforced biomimetic structural materials with excellent mechanical properties.In previous studies,short fibers are usually randomly distributed in fiber reinforced aluminum matrix composites.in order to realize the directional arrangement of fibers in aluminum matrix,fiber reinforced aluminum matrix biomimetic composites were prepared by DIW（Direct ink writing）extrusion 3D printing process and hot pressing sintering process,which solved the problem of fiber distribution in aluminum matrix.Fiber reinforced aluminum matrix composites were prepared by 3D printing and hot pressing sintering.The printing process,degreasing process and sintering process were optimized.Finally,the effect of preparation process parameters on the interface and properties of composites was studied.The results show that:1.When the DCM content of dispersant is 35 wt.%,the mass ratio of binder to solid powder（nickel-plated carbon fiber,aluminum alloy powder）is 1:20,the slurry can be extruded normally and the blank forming quality is good.When the printing speed is12 mm/s,the extrusion diameter is 0.6 mm,the printing process is smooth,the printing defect is the least,and the fiber has the best orientation effect.2.The degreasing link,the degreasing rate at different degreasing temperatures was studied.we found that the degreasing rate reached 91%at 400℃,which has a good degreasing effect.3.When the hot pressing temperature is 630℃and the hot pressing pressure is 20MPa,the hot pressing time is 20 min,the density of the composite is 95.3%.4.EDS test shows that the element distribution of the interface changed obviously during the process from the billet to the sintered sample.Through XRD detection,the phase after diffusion of the Ni layer to the carbon fiber and the Al₄C₃phase were not detected.5.After the fiber reinforced composites were prepared,The hardness,tensile and compression properties of the composites were tested.Turns out that,with the increase in fiber content,the tensile strength of fiber reinforced aluminum matrix composites increased first and then decreased,at 10 wt.%,a maximum of 137 MPa,increased by 11.84%than the tensile strength of the matrix.The greater the spiral angle,the higher the tensile strength,the tensile strength of 90°fiber spiral specimen is the highest;When subjected to x and y loads,compared to the matrix,compression strength decreased.And when subjected to z loads,the compressive strength of 90°specimen is 19.2%higher than that of the matrix.Compared with the matrix,the maximum compression modulus of 60°samples is 59.6%higher than that of the matrix when subjected to transverse load.Hardness test results showed that,with the increase of fiber content,the hardness of the composite increases first and then decreases.As the content of carbon fiber increases to 10 wt.%,a maximum of 106.85HV in hardness.This study has some reference value for the practical problems facing the design of bionic composites and the preparation of high-performance fiber reinforced composites.