| Ocean is rich in natural resources. The problems of corrosion has to be firstly considered and solved when exploring and developing the ocean. Marine ships and marine facilities are exposed to dry and wet alternate oxygen-enriched high salt fog and ultraviolet radiation environment in long term, so the corrosion problem is extremely serious. Therefore, the reasonable use of marine corrosion protection technology is of profound significance to prevent disasters and accidents, improve the safety of ships and offshore facilities and prolong the service life. Graphene and graphite nanoplate are the new two-dimensional nano-carbon materials which have a flake-like structure and exhibit a good stability and barrier property for water, oxygen and ion. When used as traditional coating pigments, they have good physical shielding effect to improve the anticorrosion performance of organic coatings.Thermal reduced grapheme oxide(RGO) and graphite nanoplate(GNP) were used as pigments respectively, epoxy resin as matrix, this paper studied the structure characteristics of RGO and GNP. Morever, the coating anticorrosion performance and its anticorrosion mechanism was discussed.Using GN as pigments, this paper evaluated the GNP coating anticorrosion performance and its anticorrosion mechanism. The prepared GNP surface was very smooth. The thickness of the layer was about 50 nm and the diameter lamella was about 2-10μm. Different amounts of GNP coatings were prepared by using GNP as pigments. Electrochemistry and salt spray tests were conducted which showed that as 10% GNP coating was added the corrosion potential and corrosion current density were-435 m V and 0.055μA/cm2, respectively, which indicated good anticorrosion properties. GNP was modified by silane coupling agent and the modified GNP coatings were prepared. The corrosion potential and corrosion current density were-416 m V and 0.032μA/cm2, respectively, when 10% modified GNP was added. It showed good anticorrosion properties. GNP has good physical shielding effect, so it can prevent penetration of corrosion medium.Additionally, the RGO was used as barrier pigments to produce homogenous coating with impressive anticorrosion behavior. XRD, Raman, XPS and SEM analysis showed that RGO contains some oxygen groups. The thickness of the layers was about 40 nm and the diameter of lamella was about 2-5μm. RGO was directly used as pigments and different contents of graphene coatings were prepared. Electrochemistry and salt spray tests showed that as 1.5% RGO was added, the corrosion potential and corrosion current density was-428 m V and 0.058μA/cm2, respectively, indicating good anticorrosion properties. RGO was modified by silane coupling agent, and the modified RGO coating was prepared with addition of 2% modified RGO which showed best anticorrosion properties, i.e. the corrosion potential and corrosion current was-360 m V and 0.034μA/cm2, respectively. The well-dispersed RGO embedded in the matrix could prevent corrosion and medium penetration. When the RGO was modified with silane coupling agent, it can improve its dispersion and interface binding force with the resin in the coating. Morever, the corrosion potential of the coating was increased ahout 68 m V,and the corrosion current was decreased about 58.6%.This paper further explored the effect of reduced temperature on the anticorrosion properties of graphene coating. At the temperatures of 450℃, 750℃, 1050℃, the RGO was prepared by thermal exfoliation. The XPS test revealed that the C/O are 6.2, 7.4 and 8.4, respectively. With the increased temperature, RGO showed a higher degree of exfoliation and the morphology of the RGO gradually changed from the hollow balls into the flake structure. Electrochemical tests revealed that the graphene coating at 1050 ℃ showed the best anticorrosion performance. At low reduction temperature, more oxygen containing groups remained, but failed to exfoliated into flake-like structure, so the properties of physical barrier and anticorrosion performance are reduced. |
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