Research On Strip Cast-rolling Controlled Forming And Mechanical Behavior Of Carbon/Aluminum Composite

Carbon fiber reinforced aluminum matrix composite（sCFRAMC）, with thecharacteristics of light weight and high strength, have been widely used in thefields of aviation, aerospace, electronics, automobiles and advanced weaponsystems. At present, the preparation methods of fiber reinforced aluminummatrix composites include liquid metal impregnation method, pressure castingmethod, diffusion bonding method, powder metallurgy method and ultrasonicwelding method, etc.. A new controlled forming method is put forward. Itcombines the liquid dipping, solidification and rolling deformation, which canimprove the mechanical properties of aluminum matrix composite plate bycontrolling the binding condition between the carbon fiber and the aluminum.The infiltration and interfacial bonding strength between carbon fiber andaluminum liquid are the precondition of gaining high performance composites.Carbon fiber with Ni coating can not only improve effectively the infiltrationbetween carbon fiber and metal fluid, but also avoid producing brittle phase dueto interface reaction between aluminum liquid and carbon fiber. Therefore, thenickel-plated on the surface of carbon fiber and the mechanical properties ofnickel-plated carbon fiber under the condition of high temperature are studied toexplore the effect of Nickel lay on carbon fiber’mechanical properties. Theresults show that the effect of nickel-plated surface treatment on the tensilestrength of the carbon fiber bundle is small, and carbon fiber bundles withNi-coating can maintain their high tensile strength of carbon fiber bundles.Under the high temperature, the carbon fiber reacts with oxygen, and formhoneycomb structure, which gradually decreases the tensile strength. Thus, inthe preparation process of CFRAMC, the way of blowing inert gas is adopted toensure that carbon fiber is isolated from oxygen. Then, the unidirectionalCFRAMC is prepared at the self-designed experimental apparatus, and itsmaximum tensile strength is up to1200MPa.The multi-field coupling model of composite forming for continuous fiberand liquid aluminum is established to explore the effect of the flow behavior of liquid aluminum on fiber-reinforced aluminum matrix composites formingprocess. Firstly, the numerical simulations about heated mold continuous castingprocess of plated-nickel’ carbon fibers coated aluminum matrix have beenperformed. The effects of the casting speed and the heat transfer coefficient onthe temperature field, solidification field and velocity field of molten aluminumin the composites forming process are given. The results show when the heattransfer coefficient is4000W m-2K-1, the maximum casting speed is1.32m/min;at the casting speed of1.2m/min, the temperature decreases gradually at thesame point with the increase of the heat transfer coefficient, however, the changeof the temperature becomes smaller when the heat transfer coefficient exceeds6000W m-2K-1. Secondly, the numerical simulations about strip cast-rollingforming process of bi-directional fiber reinforced aluminum matrix compositeshave been performed. The effects of the casting speed and the heat transfercoefficient on strip cast-rolling forming process of aluminum matrix compositesare obtained. The results show that the temperature of the liquid aluminumdecreases rapidly, the temperature reaches quickly below the solid phasetemperature, and the flow velocity becomes small in the cast-rolling zone; withthe increase of the casting speed, the speed changes more violently, the rate ofsolidification of molten aluminum becomes small, and both the temperature andthe liquid phase ratio values increase gradually at the same point; with theincrease of the heat transfer coefficient, the temperature decreases gradually, therate of solidification of molten aluminum becomes faster, while the temperatureand the liquid phase ratio decrease gradually at the same point.A unit cell models are set up for unidirectional fiber reinforced(UDFR) andbi-directional fiber reinforced(BDFR) composites. The equivalent elasticproperties of UDFR and BDFR composites are predicted respectively byhomogenization method. Firstly, the equivalent elastic properties of glass/epoxyUDFR composites are predicted. Through comparing with existing calculationresults, the correctness of this homogenization method is verified. Secondly, byhomogenization method, equivalent elastic properties of UDFR aluminummatrix composites are also predicted. Through revising NASA empirical formula, the predicting formula of unidirectional CFRAMC are gained. Finally,taking UDFR aluminum matrix composites equivalent elastic constants as thematerial parameters of the fiber bundles in BDFR aluminum matrix composite,the equivalent elastic properties of BDFR aluminum matrix composites arepredicted by homogenization method. The results show that with the increase ofthe fiber volume content, the transverse tensile modulus increase gradually andthe shear modulus decrease gradually.