Preparation And Properties Of Graphene/Aluminum Alloy Composite

7075 aluminum alloy has excellent properties such as low density,high strength-to-weight ratio,good electrical and thermal conductivity,and good corrosion resistance.It is widely used in military aircraft,electronic devices,and industrial production.With the advancement of social technology,more excellent materials are urgently needed.Due to graphene excellent mechanical properties it is often added to composite materials to improve its performance.In this paper,7075 aluminum alloy is used as the matrix,and graphene nanosheets?GNPs?are used as reinforcements.The spark plasma sintering?SPS?process is used to control the length of holding time,change the amount of graphene added,set the heating rate and adjust the different sintering temperature.After sintering the composite material,the prepared composite material is subjected to manual grinding water treatment,grinding machine polishing and streamline cutting to obtain processed samples,and then through a focused ion beam scanning electron microscope dual beam workstation and X-ray diffraction analyzer for high resolution microscopy The Raman spectrometer was used to characterize the corrosion resistance and mechanical properties of 7075 aluminum alloy materials and GNPs/aluminum alloy composites sintered by different sintering processes?graphene nanosheet content,sintering temperature,holding time,heating rate?.Happening.The main conclusions are as follows:?1?The best sintering process conditions for GNPs/aluminum alloy composite materials are:sintering temperature is 550?,temperature rise rate during sintering is50?/min,GNPs content is 0.3%,and axial pressure is applied to the powder at 50MPa,The heat preservation time to maintain the grain growth is 6min.The density of 7075aluminum alloy matrix obtained by sintering with the best process is 95.1%,and the density of GNPs/aluminum alloy composite material is 93.1%.The density is reduced due to the addition of GNPs;the composite material obtained by sintering with the best process conditions the average friction coefficient is 0.3117,and the wear rate is0.00377mm³/?N?m?,which is 43.1%and 23.8%lower than the 7075 aluminum alloy substrate,respectively;The Vickers hardness is 144.9HV,which is 26.6%higher than that of the 7075 aluminum alloy substrate.?2?The densification and mechanical properties of 7075 aluminum alloy and GNPs/aluminum alloy composite prepared at different sintering temperature,holding time and heating rate were studied.The results show that the compactness of 7075aluminum alloy and GNPs/aluminum alloy increases first and then decreases with the increase of sintering temperature and holding time;the hardness of the two composite materials increases first and then decreases with the increase of sintering temperature and holding time,and then decreases with the increase of heating rate;the friction coefficient and wear rate of the two composite materials increase first with the increase of temperature After decreasing,it will increase.?3?The results show that GNPs can be uniformly dispersed in the aluminum alloy matrix and the interface bonding is good.The phase structure spectrum shows a weak GNPs peak,and there is no Al₂O₃,Al₄C₃ characteristic peak.?4?Under the same sintering conditions,the microhardness of GNP/aluminum alloy composite is higher than that of 7075 aluminum alloy,the density of GNPs/aluminum alloy composite is lower than that of aluminum alloy,and the friction coefficient and wear rate of GNPs/aluminum alloy composite are lower than that of7075 aluminum alloy.?5?Using dynamic potential polarization curves and electrochemical impedance spectroscopy to analyze the corrosion of composite materials with different graphene contents,the results show that 7075 aluminum alloy material has the highest corrosion potential,the smallest corrosion current density and the largest impedance,and the most corrosion resistance Good;the composite material with 0.3%GNPs content has the lowest corrosion potential,the largest corrosion current density and the smallest resistance,and the worst corrosion resistance.This is because on the one hand,the presence of enhanced graphene on the surface of the aluminum alloy will split the oxide film on the surface of the aluminum alloy;on the other hand,the graphene carbon and aluminum matrix in the composite material constitute a micro-galvanic corrosion primary battery,which aggravates the corrosion;In addition,the poor wettability of graphene and aluminum matrix itself causes micro-cracks on the surface of the material to be easily corroded.The development of corrosion products of the two materials is different.The 7075 aluminum alloy material mainly develops as bulk corrosion,and when GNPs/aluminum alloy composites are corroded,a large number of tiny pits will slowly produce corrosion and expand the entire sample.