Study On 3D-SiC_f/Al Composites Manufactured Vacuum Pressure Infiltration

3D-SiC_f/Al composites have the characteristics of enabling the preform structure linked closely together, good integrity and strong continuity. The fiber bundle wrap each other in space as network-like layered;and the three dimensional braided composite materials have a good advantage of design in component preparation,which result in the integration of materials and components, and the integration manufacturing technology of the structure and functional. This makes the3D-SiC_f/Al composites with good overall performance, such as high specific strength,high specific modulus, performance designed, low thermal expansion coefficient,good heat resistant, wear-resistant, anti-aging, creep and low density. 3D-Si Cf/Al composites is one of the most potential materials in areas of aerospace.In this paper, ZL301 is chosen as the matrix alloy, and the reinforcement fiber is the SiC fiber which produced by precursor method, and the 3D fiber preform is produced by the method of three dimensional and five directional woven structure.Using vacuum pressure infiltration to manufacture the 3D-SiC_f/Al composites.Focuses on the process parameters of different preheating temperature of the 3D fiber preform and different holding pressure time, which have the influence on the density,microstructure and mechanical properties of 3D-Si Cf/Al composites. And the preliminary study on the infiltration behavior of liquid aluminum alloy in 3D fiber preform. The main conclusions are as follows:The preheating temperature of 3D fiber preform and the holding pressure time are the key factors affecting the fabrication of composite materials, under the condition of the infiltration temperature of 730?, infiltration pressure of 8MPa,holding pressure time of 20 min, the density of the 3D-SiC_f/Al composites increased with the increasing of the preheating temperature of the 3D fiber preform, and reached98.98% when at 560?;at the preheating temperature of 530?, infiltration temperature of 730?, pressure infiltration of 8MPa,the density of 3D-SiC_f/Al composite increased with the increasing of the holding press time of the pressure,when the holding pressure time at 30 min reached 99%.SEM analysis of the 3D-SiC_f/Al composites produced by Vacuum pressure infiltration method show that, it's fiber distribution is uniform, the longitudinal section show the anisotropy of the fiber in the characteristics of the three dimensional five directional braided structure; the main microscopic defects include the internal pore,the local fiber segregation, the cold partition, the microscopic shrinkage and the micro inclusions; with the increasing of preheating temperature of 3D fiber preform and holding pressure time, the fiber distribution is more uniform, and the defect of microstructure gradually reduce. The factors of liquid metal infiltrate into the 3D fiber preform, in addition to the internal and external pressure and the wetting angle, 3D fiber preform preheating temperature has a great impact on it.The mechanical properties of 3D-SiC_f/Al composites show that : with the increasing of 3D fiber preform preheating temperature, the tensile strength and flexural strength of the composites show a trend of downward after increasing first, in which at a preheating temperature of 530? reach the ultimate tensile strength of513.6MPa, the largest ultimate bending strength of 712.5MPa, and the Poisson's ratio decrease with the increasing of preheating temperature, the maximum value is 0.49 at500?; under the condition of the preheating temperature of 3D fiber preform is530?, with the time of holding pressure increasing, the tensile and flexural properties of 3D-SiC_f/Al composites show a trend of downward after increasing first, when the holding pressure time is 20 min, the maximum tensile strength reach 513.6MPa, the maximum bending strength reach 712.5MPa, and the change of the Poisson's ratio of the composite is very small, which maintain at about 0.4.In addition, the contrast tensile test of the woven SiC fiber and the original SiC fiber are carried out, the tensile strength of the fiber bundle don't affect by the 3D five directional braided process, the tensile strength is considerable with the original SiC fiber bundle, SiC fiber is suitable for three-dimensional weaving.