Repairing The Defect Of Graphene-coated Copper Towards Long Term Corrosion Resistance

There are a series of defects on the graphene film grown on the Cu substrate via chemical vapor deposition(CVD)technology,though which corrosion medium reaches the interface between graphene and copper substrate and would induce the galvanic corrosion.In this study,the accurate healing of defects to enhance the corrosion resistance of graphene without declining its conductivity was investigated.The growth mechanism of organic molecules and carbon film on the surface of graphene coated copper was studied and the relationship between the film and the defect was investigated.The corrosion resistance mechanism of graphene after the defect healing was revealed.Graphene films with different thickness were fabricated by controlling the growth process parameters of CVD.We investigated the existence of defects on graphene and the corrosion mechanism of how defects reduced graphene’s anticorrosion ability and promoted the corrosion of copper substrate.The organic molecules were selectively adsorbed on the defect site of graphene,and grafted on the exposed copper substrate via chemical bond.The growth mechanism of carbon film on graphene and the relationship between carbon film and graphene framework were studied.The mechanism of carbon film inhibiting galvanic corrosion at the defects of graphene was revealed.Novel structural design of superfast self-healing material without demanding external stimulus was obtained,and the corrosion protection mechanism in the self-healing process was studied.(1)Graphene films with different thickness were deposited on copper surface by CVD.The relationship between the number of layers and the defects of graphene,the influence of graphene defects on its corrosion resistance and the galvanic corrosion mechanism between graphene and copper were evaluated.The failure mechanism of graphene film at defect site was unveiled.Long-term corrosion resistance of graphene film was not simply increased with the increasing of layer number,instead,the defect degree of graphene was the main factors determining the protective performance.Therefore,preparing high-quality graphene is the preferred strategy to obtain long-term anti-corrosion performance.(2)The low surface energy materials(perfluorooctyltriethoxysilane and perfluorooctanethiol)were chemically grafted on the graphene coated copper at defect site by self-assembly technology.The functional treatment was to precisely heal the defects of graphene through chemical adsorption,and the healing process will not affect the structure of graphene.Micro FT-IR and transmission electron microscopy results showed that the healing material was chemically grafted on the defect site,and there was no physical adsorption on the surface of intact graphene.The accurate healing of graphene defects will not affect the structure of graphene and thus the conductivity property of graphene was not changed.Low surface energy healing material could reduce the wetting and spreading of corrosion medium,and significantly improve the corrosion protection performance of the graphene film.(3)The carbon film with only nanometer thickness was deposited on the surface of graphene coated copper by physical vapor deposition.The thickness of the film was controlled by adjusting the gas flow rate and deposition time.The growth mechanism of carbon film on the surface of graphene was investigated.The structure-performance relationship between carbon film and graphene coated copper was studied by transmission electron microscopy,and the structure of carbon film and graphene was studied by Raman spectroscopy.The corrosion protection behavior was studied by electrochemical and local impedance spectroscopy,and the influence of carbon film on the conductivity property of graphene film was revealed by surface potential.(4)Carbon nanotube was used to form the crosslinking network in oil and epoxy resin,and a superfast self-healing material with long-term corrosion protection performance was obtained through the fine structural design.A new self-healing strategy was proposed to reveal the influence of the stability and fluidity of the composite on the healing efficiency and corrosion resistance.The self-healing ability was studied in a variety of harsh corrosive environments.The corrosion protection mechanism of self-healing materials was evaluated by immersion test,erosion test,salt spray test and hygrothermal cyclic test.Scanning vibrating electrode technique was used to investigate the in-situ electrochemical behavior in the self-healing process,which verified its potential infinite self-healing ability.