Cutting Performance And Simulation Of Graphene/Al-Si Composites

Graphene is a new material with excellent performance.With high specific strength and elastic modulus,it is one of the materials with the highest conductivity and thermal conductivity known to be found in materials.It is considered as a future revolutionary material and has been applied in many fields.Especially,as a new reinforcing phase,it has been widely used in the field of composite material manufacturing.In this paper,graphene was used as the reinforcing phase,which was fully mixed with Al-Si powder and a small amount of Cu and Mg powder to prepare graphene-strengthened polymetallic matrix composite material--graphene/aluminum-silicon(Gr/Al-18Si-4Cu-Mg)composite material.Due to the strengthening effect of graphene on metal matrix,the existence of hard Si particles and intermetallic compounds Al2Cu and Mg2Si,there are many coupling factors when cutting Gr/Al-18Si-4Cu-Mg composite materials.It leads to low cutting efficiency,difficult surface quality control and poor cutting performance,which limits its application in industry.In this paper,Gr/Al-18Si-4Cu-Mg composites with different graphene mass fractions were prepared by powder metallurgy.By means of metallography microscope and XRD diffuser,it is observed that Al is the matrix phase in Gr/Al-18Si-4Cu-Mg composite materials,Si particles are dispersed in the matrix,and intermetallic compounds Al2Cu and Mg2Si are precipitated strengthened phases and mostly distributed along grain boundaries.In addition,by comparing the graphene with different mass fraction,it was found that appropriate amount of graphene can effectively refine the hard particles.By testing the mechanical properties and physical properties of Gr/Al-18Si-4Cu-Mg composites,the effect of the amount of graphene added on the macroscopic mechanics was discussed.According to Johnson-Cook thermodynamic coupling formula,the chip separation criterion and friction model were defined,and the Gr/Al-18Si-4Cu-Mg composite three-dimensional finite element simulation model was established.At the spindle speed n=1100r/min,feed f=250mm/min,and cutting depth a_p=1.4mm,the composites with a graphene mass fraction of 0.5%were simulated.The process of chip extrusion and separation is analyzed,and the results show that the simulation results of cutting force are in good agreement with the experimental results.The relationship between cutting parameters and milling forces and the influence of the variation of graphene content on the fluctuation degree of cutting forces and chip morphology were studied.The experimental results show that the milling force decreases with the increase of spindle speed.Milling force increases with the increase of milling depth and feed.On the basis of orthogonal milling experiment,the empirical formula of milling force of Gr/Al-18Si-4Cu-Mg composite for high speed steel was established.Under the cutting conditions of n=900r/min,f=200mm/min and a_p=1.1mm,by comparing Gr/Al-18Si-4Cu-Mg composites with different graphene contents,the calculated data showed that appropriate amount of graphene could reduce the fluctuation of milling force and make the milling process more gentle.Under the same cutting conditions,with the increase of graphene content,the morphology of the chips changed from banded to segmented to granular.The effects of spindle speed,milling depth and feed on surface roughness Ra were studied.The surface roughness decreases with the increase of spindle speed.The milling depth has little influence on the surface roughness.However,the effect of feed velocity on surface roughness is very sensitive,and the surface roughness increases with the increase of feed velocity.