Study On Friction And Wear Characteristics And Cutting Performance Of Graphene/Al-18Si-3Cu-0.5Mg Composites

Graphene has high strength,high elastic modulus,and also one of the best materials for electrical and thermal conductivity,which plays a significant effect as the enhancement of the performance of relative metal matrix composites.Four groups of graphene/Al-18Si-3Cu-0.5Mg composites with graphene mass fraction of 0%～0.7%were prepared by combining graphene with Al-Si powder and adding Cu and Mg in small amounts.The microstructure of the graphene/Al-18Si-3Cu-0.5Mg composites was observed by XRD diffractometer,which showed that the microstructure of the graphene/Al-18Si-3Cu-0.5Mg composites consisted of aluminum matrix,hard silicon particles and intermetallic compounds Mg₂Si and Al₂Cu;metallographic microscopy showed that the size of hard silicon particles in the four groups of composites was around3～10 um,and the silicon particle profile size of the graphene content of 0.5%was the smallest.The mechanical and physical properties of graphene/Al-18Si-3Cu-0.5Mg composites were tested.The Brinell hardness measurements showed that the hardness values of the composites with graphene content of 0%to 0.7%increased from 76.5 HBW to 86.14 HBW;the strength experimental results showed that the yield strength and tensile strength of the composites increased from 132.77 MPa and 157.77 MPa to 177.77 MPa and 252.83 MPa,respectively;the thermal conductivity experimental results showed that The experimental results of thermal conductivity showed that the composite with graphene content of 0.5%had the best thermal conductivity of 219.44 W/m-K.The frictional properties of graphene/Al-18Si-3Cu-0.5Mg composites were tested.The results of the friction experiments showed that the maximum friction coefficient of the composites decreased from 0.992 to 0.365 with the increase of graphene content;the calculated masses of the composites before and after the friction experiments showed that the wear amount of the composites decreased from 0.0287 g to 0.0141 g with the increase of graphene content;the abrasion morphology of the friction surfaces showed that the wear mechanism of the composites with 0%graphene content was mainly adhesive wear The graphene content of 0.5%of the composite material has a more regular wear pattern,with straight and shallow scratches,and the slight abrasive wear is the second most important.The improvement of the frictional properties of the composites was attributed to the improvement of the matrix strength and the refinement of the silicon particle size by graphene.The graphene/Al-18Si-3Cu-0.5Mg composites were subjected to cutting finite element simulation,a three-dimensional model of the tool workpiece was established,the cutting layer was simplified equivalently,and the Johnson-Cook material ontology model and the Ductile Damage chip separation criterion were selected to analyze the effect of graphene content on the cutting force.The experimental results showed that,under the same parameters,the overall trend of the experimental and simulated cutting force curves were similar;with the increase of graphene content,the cutting force decreased from167.66N to 135.45N;when the feed and depth of cut increased,the cutting force increased from 157.03N and 135.45N to 290.1N and 472.2N,respectively;and with the increase of spindle speed,the cutting force of The addition of graphene refined the grains and organization of the composite,enhanced the interfacial bonding of the aluminum matrix,and improved the cutting performance of the composite.The results of single particle model cutting simulation of graphene/Al-18Si-3Cu-0.5Mg composites show that the chips generated by the composites are mainly divided into two types of chips,Al matrix alone and mixed chips of Al matrix and Si particles,and when the graphene content is 0.5%,the mixed chips of matrix and Si particles are easy to occur;the removal of Si particles mainly includes Si particles fracture under the tool and the whole chip removal with the tool.The removal of Si particles mainly includes the fracture of Si particles under the action of the tool and the shedding of Si particles with the matrix,and the shedding of Si particles with the matrix is easy to occur in composites without graphene.