Effect Of Graphene On Microstructure And Properties Of Copper-tungsten Alloy

Graphene was respectively prepared by chemical reduction and 3D vibration mechanical exfoliation methods,and was characterized by the X-ray diffractometer(XRD),Raman spectroscopy,and scanning electron microscope(SEM).Subsequently,CuW70 composites reinforced by different contents of graphene were prepared by 3D vibration blending and spark plasma sintering(SPS).The microstructures of Graphcnc/CuW70 composites were examined by a scanning electron microscope(SEM),and the properties were tested as well.The following conclusions can be drawn from above investigations.The CuW70 alloy prepared by spark plasma sintering(SPS)has the optimum properties at the heating rate of 30℃/min.950℃ holding for 15min and the pressure of 35MPa.The relative density,hardness and electrical arc 98 4%,172HB and 56.7%IACS,respectively.rGO can be obtained by using SnCl2 as reducing agent and ultrasonically reducing graphene oxide(GO)for lh at 60℃ in an acidic environment(pH=3)together with vacuum freeze-drying.XRD analysis shows that the characteristic diffraction peaks of GO around 20=11° disappears,while the diffraction peak of graphene presents at 20=26°;Raman spectrum shows that the ID/IG ratio increases from 0.88 to 1.31 after GO reduction,indicating that CO is successfully reduced by SnCl2.For the rGO-reinf-orced CuW70 composites,the hardness progressively increases with increasing rGO content,whereas both the relative density and electrical conductivity decrease.At 0.6wt.%rGO,the rGO/CuW70 composite has the maximum hardness of 198HB,which is 19.3%higher than that of CuW70 alloy without rGO.Graphene(Gr)can be obtained by 3D vibration mechanical exfoliation methods.The multilayer graphite nanosheets(GNS)with low content can be peeled and thinned into few layers of graphene,but the excessive content of GNS results in the weakened thinning effect.For the Gr-reinforced CuW70 composites prepared by 3D vibration mechanical exfoliation method,the relative density increases slightly with the increase of the graphene content.At 0.0412wt.%Gr,the composite has a relative density of 96.7%,which is still higher than the national standard(96.43%).The electrical conductivity and hardness increase and then decrease with the graphene content increasing,but the overall increment is not obvious.Graphene incorporation improves the thermal conductivity of CuW70 composites.The CuW70 composite has the largest thermal diffusion coefficient at different temperatures when the graphene content is 0.015wt.%.Besides,the addition of graphene significantly enhances the arc erosion resistance of CuW70 composites.At 0.015wt.%Gr,the eroded surface presents shallow pits and less Cu splashes after vacuum breakdown 50 times,and the breakdown strength increases from 2.98×107V·m-1 to 8.15×107V·m-1.Additionally,the chopping current is reduced from 4.55A to 3.96A,and the arc duration is prolonged from 16.53ms to 18.31ms,indicating that the graphene addition can improve the arc erosion resistance of CuW70 composite.