Fabrication And Properties Of Cu-SiC-GNP Composites

Based on the unique structure and excellent propertie s of graphene,the graphene nanoplates(GNP)were added to the traditional Cu-SiC composites.In this study,planetary ball milling,cold pressing and sintering were utilised to fabricate the Cu-SiC-GNP composites,which might be a route of the efficient industrial manufacturing of Cu-SiC-GNP composites.As for a new material,processing parameters of Cu-SiC-GNP needed to be investigated first.At the beginning of study,the as-received copper and Cu-SiCGNP milled for 2h were used to find an appropriate sintering temperature.Morphology,density and hardness were all employed and analysed.The connection of grains for Cu and Cu-SiC-GNP tended to increase while the ratio of pore and void inclined to decrease.Considering both curves of density vs.sintering temperature and curves of microhardness vs.sintering temperature,the best sintering temperature for these two kinds of materials was 800 ?C.Furthermore,it was found that sintering of Cu-SiC-GNP composites was harder because of the addition of SiC and GNP with higher melting points.In the analysis of ball milling time,pure Cu and Cu-SiC were used as a comparison to Cu-SiC-GNP.Both the powders and bulk samples were analysed through the XRD,FSEM,optical microscope,automatic density measuring machine,Vickers microhardness testing machine and universal testing machine.The X-ray diffraction(XRD)result showed that there was no undesirable or just a slight volume of unexpected reaction happened within 8 h ball milling.The morphology of Cu,Cu-SiC and Cu-SiC-GNP showed the similar trend after 8 h ball milling in which most laminar(flake)particles were formed,attributing the cold welding and fracturing.In addition,densities of these three materials declined with the increase of ball milling time due to the work hardening and irregular shapes of particles.In term of hardness,the hardness of all the three materials inclined to increase generally with the increase of ball milling time,attributed to the work hardening and the refinement of particles.Whereas there was enhancement in compressive properties of Cu and Cu-SiC,the maximum of compressive stress of Cu-SiC-GNP had a tendency to decrease with the prolonged ball milling time.In addition,the yield point of Cu-SiC-GNP changed irregularly with the increase of ball milling time,which could be attributed to irregular morphology of Cu-SiC-GNP particles and the ball milling time that was not long enough to disperse both the SiC nanoparticles and graphene nanoplates homogeneously in the Cu matrix.In ball milling of Cu-SiC-GNP,the deformation and work hardening could be the main mechanism that strengthened the hardness and decreased the density with the increase of ball milling time.Furthermore,locally high internal strain was caused by the resistance to further deformation that brought about the increase of dislocation densities and grain refinement,and it increased the hardnesss.The strengthening mechanism for the compressive strength for CuSiC-GNP could be ascribed to:(i)grain refinement,(ii)load transferring from the matrix to the SiC nanoparticles and GNP,and(iii)increase in dislocation caused by the mismatch between the matrix and reinforcements.This study is a fundamental investigation of Cu-SiC-GNP composites to find out the appropriate processing parameters,the evolution of powders during milling and basic mechanical properties of the new material.In near future,a longer ball milling time of Cu-SiC-GNP will be studied to observe the variations of the powder material and bulk material.Additionally,other identification methods like etching will be used to obtain a clear distribution of porosity.Furthermore,tribological measurement will be conducted to reveal the wear resistance of Cu-SiC-GNP composites.