Study On Preparation And Mechanical Properties Of Continuous Cf/Al-Mg Matrix Composite Material Plate

In recent years,with the rapid development of science and technology,the demand for low-cost and high-performance composite materials have continued to grow.Continuous carbon fiber reinforced aluminum-magnesium-based(Cf/Al-Mg)composite material plates have the characteristics of high specific strength,high specific modulus and low thermal expansion coefficient.They also have the advantages of high temperature resistance,high thermal conductivity,electrical conductivity and radiation resistance.It has obvious advantages in material properties and design method,and can meet the requirements of aerospace and aerospace structures for material stiffness.Traditional Cf/Al-Mg composite material plate preparation methods generally have problems such as low production efficiency and many constraint conditions(such as high pressure and high temperature).Therefore,it is particularly urgent to develop a composite material plate preparation process with low production cost and high product quality.The twin-roll casting molding process integrates liquid immersion method and die-casting method.It undergoes rolling deformation while infiltrating and solidifying,which improves the problem of poor wettability between liquid aluminum and carbon fiber.It has some advantages such as low production costs,simple process flow,short cycle time,and high efficiency.In this paper,a continuous Cf/Al-Mg composite material plate was successfully prepared by a twin-roll casting forming process,and a nickel-plated carbon fiber was prepared by an electroplating process.After adjusting the cast rolling speed and cast rolling temperature,several casting experiments were carried out and discussed the influence of process parameters on the casting forming process of the composite material plate.Finally determined the reasonable process parameters,and developed a short-flow and low-cost continuous Cf/Al-Mg composite material plate preparation process.Using optical microscope,scanning electron microscope,energy spectrum analysis and tensile experiment at room temperature and other experimental methods,the effects of cast rolling temperature and Mg content on the microstructure,interface characteristics,fracture morphology and mechanical properties of cast-rolled composite material plates were studied.The whole process of pulling out fiber bundles in unidirectional fiber-reinforced aluminum-magnesium-based composite material plate was simulated by finite element method.Based on cellular automata theory,a analysis model describing the solidification process of the twin-roll composite material plate continuous casting is established to realize the simulation prediction of the plate solidification structure and mechanical properties.The main conclusions obtained are as follows:1.Under the conditions of cast rolling temperature of 680?,a cast rolling speed of 3.3m/min,and a roll gap of 2.0mm,a continuous Cf/Al-Mg composite material plate with a smooth surface and no obvious surface defects can be prepared by the twin-roll casting process.The carbon fiber is evenly distributed in the alloy matrix,and the interface is well bonded.No obvious fiber break,holes,burning and other defects are found.The mechanical properties of the composite material plate are the highest,and the tensile strength is 42.6%higher than that of the matrix material.2.By electroplating Ni on the surface of carbon fiber,a uniform and smooth metal Ni layer is prepared,which can improve the wettability between carbon fiber and aluminum matrix,prevent the chemical reaction between carbon fiber and aluminum in direct contact,and effectively inhibit the generation of Al₄C₃ brittle phase.3.The addition of Mg to the matrix significantly improves the fluidity of the alloy and improves the infiltration of the molten liquid into the carbon fiber bundle.For pure aluminum substrates,complete infiltration can be achieved at lower cast rolling temperatures.With the Mg content increase from 0wt.%to10wt.%,the tensile strength of composite material plates continues to increase.When the Mg content reaches 10wt.%,the tensile strength of the composite material plate is nearly 2.5 times higher than pure aluminum.4.Through the simulation of fiber pull-out during the tensile process of the composite material plate,the process and law of the interface debonding are studied.The simulation results show that when the load is 649N and the deformation is 0.15mm,the interface begins to debond from the two ends of the fiber embedded in the matrix,and then gradually expands to the middle of the fiber.After the deformation reaches 0.78mm,all Cohesive units are completely damaged,loss load-bearing capacity,and complete debond between the matrix and the fiber.The simulation of fiber pull-out further improves the understanding of the bond between the fiber and the matrix,helps to analyze the mechanical properties and failure mechanism of the composite material plate,and provides a theoretical basis for the preparation and performance improvement of the composite material plate,and expands its application fields..5.A analysis model describing the solidification process of twin-roll composite material plate continuous casting was established,and the solidification process of the twin-roll casting composite material plate was simulated.The solidification structure distriution characteristics,grains size and other characteristic parameters were obtained,and predict the mechanical properties of the speed belt and the plate.The simulation results are basically consistent with the experimental results,indicating that it is feasible to use the analysis model to predict the solidification structure and the mechanical properties of composite material plates under different process parameters and solidification parameters,and it has guiding significance in engineering practice.