Research On Direct Writing 3D Printing Of Continuous SiO₂ Fiber Reinforced SiO₂/Phosphate Composite And Its Properties

3D printing technology has the advantages of simple process,full utilization of raw materials and rapid prototyping of complex structures.3D printing fiber reinforced materials are currently a research hotspot,and 3D printing of continuous fiber reinforced materials only appears in FDM technology.There are few reports on the preparation of continuous fiber reinforced materials by slurry direct writing3D printing technology.In this paper,a technique for preparing continuous fiber reinforced materials by slurry direct writing 3D printing in the case of fiber-free power source is proposed.Based on the design of the printing needle structure and the regulation of the rheological properties of the slurry,based on the research background of the 3D printing wave-transparent material,the nano-SiO₂ powder and phosphate are used as raw materials,and the continuous SiO₂ fiber is used as the reinforcing phase.SiO₂ fiber reinforced 3D printing of SiO₂/phosphate composites.Studies have shown that increasing the content of nano-SiO₂ and curing agent can increase the viscosity of SiO₂/phosphate slurry,and nano-SiO₂ can improve the shear thinning behavior of the slurry and convert the basic phosphate i nto non-Newtonian fluid.The temperature has a great influence on the SiO₂/phosphate structure.As the temperature increases,the material undergoes dehydration condensation reaction to form phosphate.The solid phase composition is mainly Al（H₂PO₄）₃ and AlPO₄.SiO₂/phosphate is a low dielectric constant material with good wave transmission performance.Increasing the curing agent and SiO₂ content improve the mechanical properties and dielectric properties of the material.The finite element simulation results show that the diameter of the outer needle and the position of the intersection of the inner and outer needles in the double needle structure have a significant influence on the flow field of the slurry.The larger the outer needle diameter,the higher the position of the inner and outer needle intersections,the larger the slurry flow rate,and the fiber outlet pulp.The higher the shear rate,the more easily the fiber is taken out by the slurry.When the continuous SiO₂ fiber reinforced SiO₂/phosphate composite is prepared by 3D printing,heating the printer substrate to 50°C⁷0°C is more convenient for acceleration.The green body is solidified to improve the forming precision.The SiO₂ fiber reinforced SiO₂/phosphate composite prepared by the continuous fiber reinforced 3D printing technology designed by the subject has high molding precision,and the fibers are uniformly distributed continuously in the matrix,and the matrix is well combined.The continuous SiO₂ fiber reinforcement makes the SiO₂/phosphate material decrease the porosity and the flexural strength.The SiO₂ fiber significantly improves the dielectric properties of the material.When the SiO₂ content in the matrix is 20%,the dielectric constant of the composite is 1.2.The dielectric constant of the matrix material itself is reduced by 43.4%;the dielectric loss tangent is 1.5?10^-2,which is 70%lower than the matrix material.