| Due to long-term operation under high voltage and high current conditions,electrical contact parts such like disconnect switches,cable joints,and contact networks of high-voltage transmission and transformation systems including substations and railways are prone to abnormal heating,increased contact resistance,and frictional wear.The application of an electrical joint compound coating to the electrical contact area can greatly lower contact resistance while also acting as a lubricant,hence assisting in the resolution of the issues mentioned.The existing electrical joint compound,however,has issues such as high temperature flow,insufficient electrical conductivity,poor environmental resistance,and limited-service life.Graphene has outstanding electrical and lubricating qualities,and its usage as a filler in electrical joint compound is predicted to improve high temperature resistance,electrical conductivity,and lubricating capabilities.As a result,the focus of this study is on the development of graphene electrical joint compound featuring excellent high temperature resistance,electrical conductivity,and lubrication performance,and the main research contents and results are as follows:(1)Liquid-phase mechanical exfoliation was used to make graphene.The sheet structure,distinctive peaks,sheet thickness,and functional group structure of graphene were studied using SEM,Raman,AFM,and FTIR.The manufactured graphene flakes were translucent and flat,with a thickness of only 2 nm,high purity,and no additional contaminants,and belonged to few-layer graphene,according to the findings.(2)Using phenylmethyl silicone oil as the foundation oil,homemade graphene as the conductive filler,copper powder and graphite as the comparative conductive fillers,and homemade thixotropic agents,a series of electrical joint compounds were produced.The impacts of filler types and ratios on the electrical joint compounds’high temperature resistance,electrical conductivity,and friction qualities were explored.According to the experimental data,the drop point of the electrical joint compound reaches 330 ~oC and does not flow when graphene is 5 wt%,and the volume resistivity is lowered by 8 orders of magnitude and 4 orders of magnitude,respectively,compared to the copper powder formulation and graphite formulation,to 2×10~3Ω·cm.The contact resistance variation coefficient is lowered to 0.89 and0.68,respectively,after coating this electrical joint compound on copper and aluminum rows,which can significantly enhance the electrical conductivity of the electrical connection.The best improvement in friction and anti-wear performance of the electrical joint compound was reached at 1000 r/min,98 N,and 5 wt%graphene.(3)Polyether was used as the base oil,homemade graphene as the conductive filler,copper powder and graphite as the comparable conductive fillers,and homemade thixotropic agents were added to create a range of electrical joint compounds.The effects of filler type and ratio on the electrical joint compound’s high temperature resistance,electrical conductivity,and friction performance were explored.The results showed that when graphene was 4 wt%in the electrical joint compound,the drop point was increased to 330 ~oC and the volume resistivity was reduced by 5 and 2 orders of magnitude to 6.5×10~3Ω·cm,respectively,when compared to the copper powder formulation and the graphite formulation.After coating this electrical joint compound on copper and aluminum rows,the contact resistance coefficient was lowered to 0.87 and 0.73,respectively,significantly increasing electrical conductivity in the electrical contact region.The optimal improvement in friction reduction and anti-wear performance of the electrical joint compound was achieved at 4 wt%graphene addition at 1000 r/min and 98 N.(4)The graphene electrical joint compound,which has an ideal formulation of both polyether and silicone oil matrix,can boost the dropping point to 330 ~oC,making it a high temperature resistant electrical joint compound.Silicone oil base graphene electrical joint compound has a volume resistivity of 2×10~3Ω·cm and a polyether base graphene electrical joint compound have a volume resistivity of6.5×10~3Ω·cm,both of which are in the order of 10~3Ω·cm.The silicone oil matrix graphene electrical joint compound is suitable for aluminum-aluminum contact,whereas the polyether matrix graphene electrical joint compound is suitable for copper-copper contact.The friction reduction and anti-wear performance of the polyether-based graphene electrical joint compound is better at 1000 r/min and 98 N. |
