Study On Preparation And Properties Of Graphene Reinforced Aluminium Matrix Composites

In this paper,multilayer graphene was used as a reinforcement,and high-energy ball milling and powder metallurgy combined with hot pressing were used to prepare aluminum matrix composites with different graphene contents.Microstructure characterization and phase analysis were carried out by optical microscopy,scanning electron microscopy,X-ray diffraction and Raman spectrometer.Corresponding performance tests were carried out on the density,hardness,compression properties and friction corrosion properties of the prepared samples.At the same time,the influence of the ball milling process on the microstructure and the influence of the sintering process on the mechanical properties were explored.The mechanism of the effect of microstructure on the macro-mechanical properties of composites was preliminarily discussed.The study of the prepared graphene/aluminum composite powder shows that the groove on the surface of the aluminum powder contributes to the adhesion of graphene.When the ball to material ratio is 5:1,the graphene is uniformly dispersed in the aluminum powder,and the mixing is relatively uniform.No particularly obvious agglomeration or segregation occurs,which indicate that the dispersion is best.Thermodynamic analysis shows that the interfacial reaction of graphene/aluminium composite powders is spontaneous during high energy ball milling.The interfacial reaction of Al₄C₃ hard and brittle phase can be formed.In this experiment,the maximum content of graphene micro-sheets which can disperse on the surface of aluminium powder is 0.5wt%.The results of sintering process and graphene/aluminium composites show that the sintering temperature has a significant effect on the mechanical properties of graphene reinforced aluminium matrix composites.With the increase of sintering temperature,the Vickers hardness of the composites increases,and the mechanical properties of the composites are the best at 600℃.During the sintering process,the microhardness increases slightly with the increase of sintering holding time,when the sintering time is 5h,the mechanical properties of the composite are best.As the hot isostatic pressure increases,the Vickers hardness of the composite increases gradually.When the hot isostatic pressure is 8t,the Vickers hardness of the composite is 59.30HV.Compared with the hot isostatic pressure of 4t,the value is increased by9.43HV,an increase of 18.9%.The effects of graphene content on the microstructure of the composites were also discussed.The properties and strengthening mechanism of graphene reinforced aluminum matrix composites show that the densities of the four composites tested in this experiment have reached more than 96%.When the content of graphene reaches 0.3wt%,the Vickers hardness of the composite is the highest value of 65.40 HV,which is 18.8%higher than that of pure aluminum.When the graphene content is between 0.1wt%and 0.3wt%,the yield strength of the composite increases with the increase of graphene content.When the graphene content is 0.3wt%,the yield strength of the composite is up to 193.85MPa,which is 27.1%higher than the value of the pure aluminum matrix.The friction coefficient of the composite with a graphene content of 0.3wt%in the 3.5wt%NaCl solution remained almost constant,especially in the middle and late stages of friction corrosion.Finally,the strengthening mechanism of graphene reinforced aluminium matrix composites was discussed based on the microstructure and mechanical properties of the composites.