Preparation And Properties Of Graphene-reinforced Aluminum Matrix Composites

As a new two-dimensional carbon material,graphene(GN)has excellent mechanical and electrochemical properties.It is a hot topic in recent years to add GN into aluminum matrix to improve the comprehensive performance of aluminum-based composite materials.Theoretically,add GN in aluminum matrix can greatly improve the performance of aluminum-based composite materials.Up to now,the problems about the poor dispersion of GN in the aluminum matrix and the poor wettability of the interface between the GN and the aluminum matrix have not been effectively solved.The surface of GN was chemically modified to prepare the modified graphene powder(GN-CeO₂).the Al/GN-CeO₂ternary composite powder was prepared by high-energy ball milling process and the Al/GN-CeO₂composites was prepared by vacuum hot-pressing sintering process.Firstly,the process parameters of preparing Al/GN composites and powders were systematically studied.the morphology and structure of the prepared Al/GN composite powders and composites were analyzed by means of characterization techniques such as laser particle size meter,X-ray diffraction(XRD)and scanning electron microscopy(SEM).The optimum preparation process of Al/GN composites was determined.When the amount of graphene added was 1wt.%(mass fraction),the ball grinding time was 1h and the sintering temperature was 590?.The GN and aluminum powder in the Al/GN composite powder are uniformly compounded.After hot press molding,the Al/GN composite material has a tensile strength of 319.35MPa,a tensile strain of 10.5%,and a hardness of 97.3HV.Compared with pure aluminum under the same experimental conditions,the tensile strength of Al/GN composites increased by 22.75%and the hardness increased by 29.6%.The conductivity of Al/GN composite is 30.24%IACS which is 3.19 IACS%lower than that of pure aluminum.Secondly,the surface of GN was modified by chemical reduction.The influence of acidification process on the structure and functional group content of GN was mainly studied,and then GN-CeO₂powders with different CeO₂deposits were prepared by controlling the hydrothermal reduction time in the chemical modification process.After the acidification process,the functional groups and defects on the GN surface are increased,which is conducive to the deposition and composite of graphene and CeO₂particles.The phenomenon of graphene agglomeration after the hydrothermal reduction process is improved.The deposition amount of CeO₂on GN surface gradually increased with the increase of hydrothermal reduction time.Finally,Al/GN-CeO₂ternary composite powder and composite materials were prepared and their properties were tested.The experimental results show that the tensile strength of Al/GN-CeO₂composites obtained under hydrothermal reduction for 6 hours reached 314.75MPa The tensile strain rate is 12.3%.Compared with pure aluminum materials under the same experimental conditions,the tensile strength of Al/GN-CeO₂composites is increased by 20.99%and the hardness is increased by31.2%.The conductivity of Al/GN-CeO₂composite is 33.21%IACS,which is 0.22%IACS lower than that of pure aluminum.The chemically modified GN-CeO₂powder added to the aluminum matrix is beneficial to the improvement of the mechanical properties of the aluminum matrix composite and has little effect on the conductivity of the aluminum matrix composite.