Microstructure And Properties Of Continuous Quartz Fiber Reinforced Phosphate Polymer Composites

Quartz fiber reinforced phosphate polymer composite has good properties of mechanical,dielectric and high temperature resistance.It is one of the first choice materials for a new generation of missile radome.In this paper,2D plain quartz fiber reinforced phosphate polymer composite was prepared by hand paste molding and low temperature curing.By adjusting the reaction parameters of phosphate polymer to optimize the matrix composition of composites,the influence of matrix composition on the properties of composites was studied.Meso-handling multi-scale homogenization finite element method,through the establishment of representative volume element(RVE)composite multi-scale finite element model,and implements the macroscopic elastic properties of the composites,to simulate the composite thermal shock stress response,fiber volume fraction is studied,the thermal shock temperature and substrate properties of thermal shock resistance of the composites.The results show that the phase composition of phosphate matrix is mainly Berlinite phase,low temperature calcareous Al PO4 and ?-Al2O3.The microstructure of the matrix is composed of continuous Al PO4 coated and bonded Al2O3 particles,and the microstructure of the composite is uniform and dense.When P/Al = 4.1,Cr/Al/P = 0.04,the compound material mechanics performance is the best,the tensile strength is 108.6MPa,tensile modulus is 23.4 GPa,bending strength is 135.3MPa,the fracture toughness K?C is 6.6MPa·m1/2,the work of fracture is 3393 J/m2,the composite has the characteristics of plastic fracture with weakly bound interface,according to the analysis,at this time,the matrix contains more Al(H2PO4)3 phases with good bonding performance,and the matrix morphology is planar,which is conducive to the formation of a complete and continuous good interface layer between the matrix and the fiber.In addition,the dielectric constant is 3.8,and the dielectric loss fluctuates within the range of 6.54×10-3?7.35×10-3,which can meet the performance requirements.Mechanics simulation results show that the finite element method compared with mixed rules and Chamis formula can more accurate and reliable prediction of the elastic constants of fiber bundles,when the fibre volume fraction is 80% in the fiber bundle and the modulus of matrix elasticity is 10 GPa,the finite element method predicts the composite material of E1 was 27.1 GPa,consistent with the experimental results,which shows that the accuracy of the finite element method,and it can be used to forecast the composite elastic properties,and provide reference for material development and design.The results of thermal shock simulation show that the thermal stress is higher in the area with less matrix and near the narrow surface of the fiber bundle head,and it is easy to cause material failure during thermal shock.After thermal shock at 1000?,the maximum thermal stress in the fiber bundle is 80 MPa,and the maximum thermal stress of the composite material is 172.3MPa.The fibre volume fraction of fiber bundles have less effect on the material thermal shock resistance,but the change of thermal expansion coefficient caused by the change of matrix phase has a great influence on the thermal shock resistance of composites,when the main phase in the matrix is T-Al PO4,the maximum thermal stress of composites is as high as 1426 MPa.When thermal shock temperature increases 200?,the maximum thermal stress in composite materials increases about 36 MPa,composite material has good thermal shock resistance below 600?.The greater the matrix modulus is,the worse the thermal shock resistance of the material will be,but large modulus means higher mechanical strength,the balance between the two aspects needs to be sought.