Study On Process Of 3D-C_f/Al Composites Manufactured Vacuum Pressure Infiltration

Compared to Cf/Al composites,3D-Cf/Al composites not only have lightweight,high strength, high stiffness, good wear resistance and other excellent high temperature strength, but also have better temperature performance and corrosion resistance,stability.3D-Cf/Al composites are much concerned in aerospace and national defense,and have been developed into one of most strategic of structural materials. With the advantages of easy to control the the infiltration pressure,the preform is not easy to deform and destruct the preform,strong adaptability and even strength of parts,low cost and achieving near net forming,vacuum pressure infiltration method is the mainly near net forming technology of 3D-Cf/Al composites.Distinguished to 3D fiber reinforced resin matrix and ceramic matrix composites,carbon fiber and metal matrix have poor wettability,the extent interfacial reaction can not be control easily,and then 3D fiber reinforced metal matrix composites’ application has lagged far behind the first two composites.In this paper,reinforcing material was graphite fiber M40 and matrix alloys was ZL301 aluminum alloys,the fiber preform was reinforced by contunious fiber(Vol. 40%)and five to three dimensional woven carbon fiber(Vol. 51%),prepared by the vacuum pressure infiltration of Vol. 40% Cf/Al composites.The study focused on the interfacial process of 3D-Cf/Al composites and the effects of preheating temperature on relative density and mechanical properties of 3D-Cf/Al composites.The following researches:The process parameters of impregnated completed Cf/Al composites: Dwell time is greater than 8 min, infiltration temperature higher than 700 ℃, the preheating temperature higher than 450 ℃.Based on the experiment of the unidirectiona arrangement of fiber preform,this paper carried out vacuum pressure infiltration of 3D Cf/Al composites with three-dimensional five-directional braided preform by fiber M40 and ZL301 alloys as matrix alloy.To analysis the microstructure,relative density and mechanical properties,get the best process parameters of 3D-Cf/Al composites:Dwell time is 20 min,infiltration temperature is 730 ℃ and the preheating temperature is500~550 ℃.3D-Cf/Al composites’ infiltration mechanism was different from unidirectionalCf/Al composites’. Distinguished to Simple unidirectionally aligned with the direction of the preform impregnated with the channel,three to five braided preform infiltration channel was complex,and then 3D-Cf/Al composites complete impregnation process conditions was higher than unidirectional Cf/Al composites.When preheating temperature was 450 ℃,unidirectional Cf / Al composites can complete infiltration and its relative density was higer than 95%.When preheating temperature were 440 and470℃,the relative density of 3D-Cf/Al composites was 88.09 and 89.91 %,the infiltration could not complete and the structure was not dense.When preheating temperature was up to 500 ℃,relative density was higer than 95% and the structure was dense.Preheat temperature is 3D-Cf/Al composite density and tensile strength of the key factors.When the Preheating temperature is 440, 470 ℃, the 3D-Cf/Al composite is not dense and combined with the weak interface, the tensile strength of 396.37 and 575.42MPa;When the Preheat temperature higher than 500~550 ℃, 3D-Cf/Al composite and interface reaction moderate interface bonding is strong, the tensile strength is greater than 770 MPa;When the Preheat temperature is 600 ℃, The compact structure of3D-Cf/Al composite, but the excessive interface reaction, generate a large amount of brittle phase Al4C3, fiber enhancement effect is greatly reduced, the tensile strength of349.58 MPa.3D-Cf/Al composite are less likely than one-way Cf/Al composite fibers together.3D-woven prefabrication body fiber between each other constraints, the relative position between the impregnation process of fiber is not easy to change,one-way permutation prefabricated fiber between relatively independent body, under the action of external force is prone to offset, reunion, when the preheating temperature,impregnation temperature is not high, the matrix alloy liquidity is poorer, unidirectional Cf/Al composite materials than 3D-Cf/Al composite materials are more likely to happen fibers together.The same process condition, the ensile strength of unidirectional Cf/Al composites as a whole than in 3D-Cf/Al composite, with the increase of preheating temperature,tensile strength difference decreases, and preheat temperature higher than 600 ℃ when the tensile strength.When the preheating temperature of 450 ℃ for 3D-Cf/Al composite tensile strength is 403.57 MPa, unidirectional Cf/Al composite tensile strength is 588.50 MPa, unidirectional Cf/Al composite tensile strength is greater than 3D-Cf/Alcomposite;When preheating temperature is 530 ℃, 3D-Cf/Al composite tensile strength is 782.33 MPa, unidirectional Cf/Al composite tensile strength is 887.71 MPa,unidirectional Cf/Al composite is still higher than 3D-Cf/Al composite;When preheating temperature is 600 ℃, 3D-Cf/Al composite tensile strength is 349.58 MPa,unidirectional Cf/Al composite tensile strength is 348.21 MPa, the tensile strength is similar.