Effect Of Rare Earth Element Ce/Y On Mechanical Properties And Corrosion Resistance Of Cf/5056Al Composite

Carbon fiber reinforced aluminum matrix composites have better mechanical properties,electrical conductivity,and low thermal expansion coefficient than aluminum alloys.However,carbon fiber reinforced aluminum matrix composites have more interfaces than aluminum alloys.Corrosion will occur preferentially at the interface joints,which will lead to corrosion failure of composite materials.Therefore,the corrosion mechanism and protective measures of composite materials need to be further developed.In this paper,Cf/Al composites were prepared by liquid phase pressure infiltration method with 5056Al aluminum alloy as the matrix and M40J carbon fiber cloth as the reinforcement.The effect on the mechanical properties and corrosion behavior of Cf/Al composites was explored by adding different contents of rare earth elements(Ce/Y)in the matrix.Use scanning electron microscope,laser confocal microscope,transmission electron microscope,atomic force microscope,analytical balance,salt spray test chamber and electrochemical workstation to test and analyze the microstructure,mechanical properties and corrosion properties of Cf/Al.The research results show that the prepared Cf/Al composite material has good impregnation and the density is higher than 99%.With the addition of rare earth elements,the hardness and bending strength of composite materials show a trend of increasing first and then decreasing.The bending strength of the composite material with 0.2wt.%Ce is 516MPa,and the composite material with 0.2wt.%Y is 495MPa.,The mechanical properties of the two are the best,an increase of 37.22%and 31.64%compared with the 376MPa of Cf/5056Al.The electrochemical corrosion behavior of 5056Al and Cf/5056Al was compared,and the study found that the corrosion current density of 5056Al and Cf/5056Al composites exhibited periodic changes with the immersion time in 3.5%Na Cl solution.The AC impedance spectroscopy shows that the corrosion behaviors of 5056Al and Cf/5056Al are not consistent.The impedance spectroscopy of 5056Al is capacitive reactance arc mode and that of Cf/5056Al composites is capacitive reactance diffusion mode.The total impedance of Cf/5056Al is much lower than that of 5056Al,and the corrosion resistance of the composite material is greatly reduced.The influence of rare earth elements on the corrosion behavior of Cf/5056Al composites was explored.The salt spray corrosion weight loss test found that composites with 0.1wt.%Ce and 0.2wt.%Y added to the matrix have the best corrosion resistance,Cf/5056Al The composite material has the worst corrosion resistance.It was also found through electrochemical tests that with the increase of the content of rare earth elements in the matrix,the corrosion resistance of the composite material increased first and then decreased.The corrosion current densities of Cf/5056Al+0.1Ce and Cf/5056Al+0.2Y are 6.73?A·cm^-2 and 1.72?A·cm^-2,respectively.Compared with the corrosion current density of Cf/5056Al,19.09?A·cm^-2,there is a significant decrease.The effect mechanism of the addition of rare earth elements on the Cf/5056Al composite material is:on the one hand,the rare earth elements will segregate at the interface after being added,and the appropriate amount of rare earth elements will be distributed at the interface to inhibit the formation of Al₄C₃;on the other hand,rare earth elements will be distributed at the interface.The addition of elements will also change the electrode potential of the matrix at the interface of Cf/5056Al which is in contact with the carbon fiber.With the addition of an appropriate amount of rare earth elements,the electrode potential of the matrix at the interface will be increased,thereby slowing down the rate of galvanic corrosion.