Prepared Carbon Fiber Reinforced Aluminum Matrix Composite By Ultrasonic Vibration Method

In recent years, carbon fiber reinforced aluminum matrix(CF/Al) composite has been widely applied in the field of structural materials because of its high modulus and specific strength, structure designability and thermal conductivity. So far, many scholars have carried out a series of researches on the manufacture of carbon fiber reinforced aluminum matrix composite, and making a compound of carbon fiber and aluminum matrix by diffusion bonding method, squeeze casting technology and gas pressure infiltration method were studied more. According to the analysis of the present manufacturing techniques of carbon fiber reinforced aluminum matrix composite, it is still impossible to put the technology of composite in large-scale application, which is due to the complicated procedures and high cost of manufacturing. Therefore, a new method of manufacturing CF/Al composites by ultrasonic vibration is proposed in this thesis. And by using scanning electron microscopy(SEM), rigaku single crystal XRD diffractionmeter(XRD), energy dispersive spectroscopy(EDAX), brinell durometer and tensile machine, microstructure and formation mechanism of composite materials were investigated. In addition, mechanical properties of composite materials were tested, and related factors were analyzed.The results shown that the particle in the liquid taken place displacement due to the shock wave is propagated in the liquid aluminum, CF/Al composites can be manufactured successfully by using self-made carbon fibred prefabricated bracket. The spacing of carbon fibers increased with the increasing of amplitude, when the ultrasonic amplitude increased from 20 μm to 30 μm, the average spacing of carbon fibers increased from 3.8μm to 7.5 μm;With a certain retightening force, the difference of carbon fibers spacing between the theoretical state and actual state was 2.95μm, in the effective range of ultrasonic amplitude for manufacturing CF/Al composites. Due to the ultrasonic wave force on carbon fiber did not change, as well as the restriction from pre-tightening force, The spacing of carbon fibers did not increase with the increasing of vibration time.In the experiment carbon fibers direct contacted with Al and then generation of a certain amount of brittle phase Al4C3 at the interface. And use of nickel coating on the surface of the reinforced fiber, can enormously inhibit the adverse reactions between carbon fibers and aluminum matrix so that composite materials with good mechanical properties can be manufactured successfully.The results shown that in the effective range, the spacing of carbon fibers increased with the increasing of amplitude, the composite materials began to break when the matrix did not carry the load transferred to all carbon fibers, therefore, The ultimate tensile strength of composites declined with the increasing of amplitude.Nevertheless, the UTS of composites increased obviously with the increasing of vibration time, when the vibration time increased from 5s to 20 s, the UTS of composites increased from98 MPa to 124 MPa. Besides, the research of fracture mechanism showed that the crack of composites first appeared at the defect area of composite matrix, where the matrix strength was relatively weak, and then the crack expanded gradually.