| Three-dimensional carbon fiber reinforced aluminum matrix composites(3DCf/Al composites) have lightweight, high specific strength, high specific stiffness,temperature resistance, structural stability, good corrosion resistance, scratch resistance and impact resistance. In addition, the three-dimensional woven structure overcome the problems that the anisotropic of traditional unidirectional composites and easy delamination, low interlaminar shear strength and poor impact resistance of laminated composites. 3D-Cf/Al composites have broad application prospects in high technology fields because of their many advantages including low production cost and designability of structure. Vacuum pressure infiltration method can prepare components of precise size and complex shape with fabrication and forming integrated to avoid damage of the fibers continuity on the second processing. What is more, Vacuum pressure infiltration is an advanced near net forming technology which have short cycle times and low producting costs. Therefore, to achieve preparation of Cf/Al composites with low cost and high performance by vacuum pressure infiltration is important for promoting the large-scale engineering applications.In this paper, reinforcing materials were M40 fibers, matrix alloy was ZL301 aluminum alloy, 3D braided perform were 3D five-directional braided structure and 3D orthogonal braided structure, carried out vacuum pressure infiltration test of 3D-Cf/Al composites. The study focused on the effect of preheating temperature and weave method on microstructure and mechanical properties of 3D-Cf/Al composites in the temperature ranging from 530℃ to 590℃.The results show that there are more tissue flaws and less fiber agglomeration in3 D five-direction braiding Cf/Al composites than 3D orthogonal braiding Cf/Al composites in the same impregnation process parameters. Fiber agglomeration decreased, fiber distribution became more uniform and tissue defects decreased with increase of fiber preheating temperature in 3D five-direction braiding Cf/Al composites and 3D orthogonal braiding Cf/Al composites. The main tissue flaws are the pores between the fiber beam and pores within the fiber beam at preheating temperature of530℃ and 550℃ in 3D five-direction braiding Cf/Al composites. In fiber preheating temperature 530℃ and 550℃, fiber agglomeration is obvious in 3D orthogonal braidingCf/Al composites. While the preheating temperature more than 570℃, fiber distribution became uniform in the morphology of vertical plane and horizontal plane, but fiber agglomeration always exist in flat morphology. What is more, the main tissue flaws of3 D orthogonal braiding Cf/Al composites are pores between the fiber beams.The results of tensile test indicate that the tensile strength, the tensile modulus and the poisson ratio of 3D five-direction braiding Cf/Al composites are higher than 3D orthogonal braiding Cf/Al composites, but the elongation is smaller than 3D orthogonal braiding Cf/Al composites in the same impregnation process parameters. The tensile strength and tensile modulus of 3D five-direction braiding Cf/Al composites and 3D orthogonal braiding Cf/Al composites present increased first then decreased with increase of fiber preheating temperature. In which, both of them reache to the maximum that tensile strengths were 753 MPa and 644 MPa, tensile modulus were 194 GPa and150GPa respectively at fiber preheating temperature of 570℃. The poisson ratio of 3D five-direction braiding Cf/Al composites increases with increase of preheating temperature, while the poisson ratio of 3D orthogonal braiding Cf/Al composites is small and keep no change almost. Their poisson ratios are 0.89 and 0.04 respectively at fiber preheating temperature of 570℃. The elongation rate of 3D five-direction braiding Cf/Al composites and 3D orthogonal braiding Cf/Al composites decrease with increase of fiber preheating temperature, their elongation rates are 5.91 and 7.18 respectively at fiber preheating temperature of 570℃.The results of bending test show that the bending strength and the flexural modulus of 3D five-direction braiding Cf/Al composites are lower than that of 3D orthogonal braiding Cf/Al composites in the same fiber preheating temperature. The bending strength and the flexural modulus of 3D five-direction braiding Cf/Al composites present increased first then decreased with increase of fiber preheating temperature and reache to the maximum of 931 MPa and 134 GPa respectively at fiber preheating temperature of 570℃. While the bending strength and the flexural modulus of 3D orthogonal braiding Cf/Al composites decrease with increase of fiber preheating temperature and reache to the maximum of 1171 MPa and 160 GPa respectively at fiber preheating temperature of 530℃.The fiber show uneven and distribute to multiple directions for the tensile fracture of 3D five-direction braiding Cf/Al composites. While the tensile fracture of 3D orthogonal braiding Cf/Al composites is flat relatively, more fiber bundles distribute to the direction plumbing tensile direction. Both of them have the phenomenon that fiberbundles are pulled out. What is more, fiber bundles tilte toward the bending direction and show uneven for the bending fracture of 3D five-direction braiding Cf/Al composites, but this phenomenon do not appear in 3D orthogonal braiding Cf/Al composites, and the bending fracture of 3D orthogonal braiding Cf/Al composites are similar to their tensile fracture. There are two damage modes for 3D five-direction braiding Cf/Al composites and 3D orthogonal braiding Cf/Al composites, one is tensile fracture, the other is shear damage. In which the longitudinal fiber bundles present tensile fracture while the fiber bundles with an angle to the direction of tensile show shear damage mainly. Tensile damage and shear damage are two damage modes for flexural fracture, the inside surface which under pressure present shear damage, while the outside surface which under tension show tensile damage. |
PDF Full Text Request