Study On Preparation And Performance Of Continuous Carbon-fiber Reinforced Aluminum Matrix Composites

Continuous carbon fiber reinforced aluminum matrix composites have high specific strength and modulus, low CTE, good dimensional stability and other excellent mechanical and physical properties, shown great potential in many fields such as aeronautics and astronautics. In this paper, vacuum pressure infiltration method for the preparation of continuous Cf/Al composites and preparation technology of carbon fiber reinforced Aluminum laminate(CRALL) were studied to fabricate high performance of continuous Cf/Al composites.The continuous Cf/Al composites were prepared by vacuum pressure infiltration method, with the 780℃ impregnation temperature and 600℃ preform preheating temperature, the infiltration pressure was 1.5 MPa of Nitrogen pressure, then cooling by water. Low preheating temperature was unfavorable for the infiltration process, so the density of the composites was low. But if the preheating temperature was too high, the interface reaction would be serious. Increased infiltration pressure was beneficial to the infiltration process, so as to improve the material density, and decrease the holes. Al2O3 coating prepared by sol-gel method can evenly cover Cf, and provide good protection to Cf. Al2O3 coating can prevent the interface reaction between Cf and Al, inhibiting formation of Al4C3- the production of interface reaction, therefore interface of Cf/Al was clean.Otherwise, Al2O3 coating improved the wettability of Cf/Al, making infiltration more completely, so the composites had a better tensile strength.Due to the negative CTE of Cf,the CTE of continuous Cf/Al composites decreased with increasing of temperature, less than 10×10-6K-1(30 ℃-200 ℃), lower than the CTE of Al matrix. This characteristic benefits from the negative CTE of Cf. For this reason continuous Cf/Al composites exbibit good dimensional stability.The tensile strength of CRALL prepared in the experiment reached 1010 MPa, with 20.8% Cf volume fraction, closing to the theoretical strength. With decreasing the curing pressure, the tensile strength of CRALL decreased. By its microstructure observation, internal adhesive layer thickening could be found, and Cf-reinforced layer appears stratification. After surface treatment, Al plate increases its surface area, and enhancing the interface bonding between Al plate and epoxy resin adhesive, increase interlaminar shear strength of composite board, so as to improve the tensile strength of CRALL. Experiments prove that the high performance CRALL can be made by commercially available carbon fiber prepreg.