| The material of the substation grounding grid is mainly carbon steel and galvanized steel.The corrosive ions in the soil will cause serious corrosion,which will affect the safe and stable operation of the power supply system.Solving the corrosion problem of the grounding grid and prolonging its service life is very important.Brushing conductive anti-corrosion coating is one of the important anti-corrosion technologies for grounding grid.Conductive coating applied to grounding grid must have good electrical conductivity,corrosion resistance and durability.However,there are certain defects in the method,such as the aging of the coating itself and the pinhole defects in the coating layer.Therefore,it is of great significance to develop a new type of highly efficient conductive anti-corrosion coating for grounding grid.In this paper,rGO-PPD-MWCNT nano-hybrid material was prepared by chemical grafting of graphene oxide(GO)and multi-walled carbon nanotubes(MWCNT)with p-phenylenediamine(PPD).A new conductive coating was prepared by filling it as an electrically conductive filler into an epoxy-based coating.The morphology of nano-hybrid materials was studied by Fourier transform infrared spectroscopy(FTIR),X-ray powder diffraction(XRD)and scanning electron microscopy(SEM).The ratio of graphene to carbon nanotubes and different nano-hybrid materials were discussed.The physicochemical properties,electrical conductivity and electrochemical properties of conductive coatings prepared under different coupling conditions of graphene and carbon nanotubes,different nano-hybrid materials,and different coupling agents and dispersants were investigated.And draw the following main conclusions:(1)After the grafting of graphene oxide and p-phenylenediamine,chemical grarfiting can be performed with the acidified carbon nanotube to form rGO-PPD.MWCNT nano hybrid material,By measuring the electrical conductivity of the prepared nano-hybrid material,the results show that when the ratio of graphene to carbon nanotube is 1:3,the resistivity is at least 3.2×10-6 ?·m,and the resistivity is 1:3<1:2<1:1<2:1<3:1 is sequentially increased.The chemical graft structure facilitates the dispersion of MWCNT and rGO,and the MWCNT scaffolding prevents the re-stacking of rGO sheets,and the prepared nano-hybrid material has good dispersibility.(2)The conductive coatings with rGO-PPD-MWCNT nano-hybrid material as filler were prepared by three kinds of coupling agents.The results show that the order of performance improvement of coatings from strong to weak is KH560>KH550>KH570.When the content of KH560 is 3%,the coating performance is the best.At this time,the resistivity of the coating reaches a minimum of 1.90×10-4?·m,and the hardness is also improved from 4H to 6H,and the adhesion is optimal.(3)Three kinds of dispersing agents were added to the prepared conductive coating.The results showed that Triton X-100 was superior to SDBS and CTAB.When the content of Triton X-100 is 0.6%,the nano-hybrid nano-coating performance is optimal.At this time,the resistivity is reduced from 6.3×10-3?·m coating to 5.725×10-3?·m,which is reduced by an order of magnitude;the hardness is also increased from 4H to 6H,and the corrosion current density is 1.569×10-7A/cm2,which reduced by two orders of magnitude..(4)After optimization experiments,the best conductive anti-corrosion coatings were obtained.That is,the ratio of graphene to carbon nanotubes is 1:3,the filler of nano-hybrid material is 1.5%,the content of silane coupling agent KH560 is 3%,and the content of dispersant Triton X-100 is 0.6%,the performance of conductive anti-corrosion coating reaches optimal.At this time,the volume resistivity of the coating is 1.90×10-4?·m,and the conductive material in the national standard is considered to have a resistivity lower than 10-2?·m,and the resistivity of the prepared coating is superior to the national standard.The results of electrochemical experiments show that the polarization resistance of the prepared conductive coating is 14 times larger. |
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