Design,Preparation And Properties Of Lubricating,Wear-Resisting And Corrosion-Resisting Functional Coatings

In the complex and changing marine service environment,"wear-corrosion"coupled damage has become a key common problem and bottleneck that restricts the efficient,stable and long service life of modern offshore equipment.Traditional solid lubrication protective coating materials have been difficult to meet the needs of high-end offshore equipment in the marine environment of high reliability and long life applications.Therefore,the development of lubrication,wear and corrosion resistant functional integrated coating for the harsh marine environment is of great practical significance to solve the corrosion and wear problems of key moving parts of offshore equipment.In this paper,based on the concept of combining active protection by chemical corrosion inhibition and passive defense by physical barrier,SrCrO₄/PTFE/EPN,nano-CeO₂/PTFE/EPN and BTSA/PTFE/EPN coatings with good corrosion resistance and tribological properties were designed and prepared using corrosion inhibitors,lubricants and phenolic epoxy resins.Its anti-corrosion performance and tribological performance under dry friction and corrosive media conditions were investigated,the enhancement mechanism and corrosion inhibition mechanism of the corrosion inhibition structure were explored,and the synergistic protection mechanism of lubrication,wear and corrosion resistance of the composite coating was analyzed in depth to provide theoretical and technical support for realizing the green and chromium-free corrosion inhibition structure and solving the bottleneck problem that restricts the reliability and lifetime of modern offshore equipment.The main research contents and results are as follows:Strontium chromate（SrCrO₄）can passivate with the substrate and produce a corrosion-inhibiting passivation layer,especially when the addition amount is 4%of the resin mass,the coating structure is dense and the passivation effect is the best,the low frequency impedance modulus value and corrosion current density are1.06×10¹¹Ω·cm²and 0.28×10^-10A·cm^-2respectively.The shielding and barrier properties were significantly improved,and the neutral salt spray resistance exceeded180 days.In addition,the friction coefficient of the coating is reduced by about73.90%compared with that of EPN coating,and the wear resistance is improved by3.2 times.Under the friction conditions of corrosive media,the coating exhibits a lower friction coefficient of 0.049 and is able to form a passivated protective film based on Fe and Cr oxides,hydroxides or crystalline hydrides at the contact interface of the friction substrate,which effectively inhibits the wear of the couple surface due to corrosion.Cerium oxide nanoparticles（nano-CeO₂）can be used as an alternative to chromate as a chromium-free corrosion inhibition structure,especially when introduced at only 2%of the resin mass,the coating has fewer defects and a dense structure,with the most significant passivation effect,the low frequency impedance modulus value and corrosion current density are 4.49×10¹⁰Ω·cm²and0.37×10^-10A·cm^-2respectively.The coating is hydrophobic and has improved shielding and barrier properties,and its neutral salt spray resistance exceeds 210 days without obvious signs of corrosion,which is better than the SrCrO₄composite coating.Due to the enhanced effect of nano-CeO₂and the excellent lubrication properties of PTFE,the friction coefficient of the composite coating is reduced by approximately77.43%compared to the EPN coating,and the wear resistance is improved by 6.8times;under corrosive media friction conditions,the composite coating shows a lower friction coefficient（0.044）,and due to the corrosion inhibiting effect of nano-CeO₂on the friction substrate,the composite coating still maintains a good performance in corrosive media friction.2-（1,3-benzothiazol-2-ylthio）butanedioic acid（BTSA）is also capable of acting as a chromium-free corrosion inhibition structure,especially when BTSA is added at8%of the resin mass,the coating structure is dense,the passivation effect is most significant and the coating exhibits a high low-frequency impedance modulus(3.43×10¹⁰Ω·cm²)and a low corrosion current density(0.54×10^-10A·cm^-2).The introduction of PTFE transforms the coating into hydrophobic while enhancing the shielding and barrier properties,and its resistance to neutral salt spray tests for more than 210 days shows no obvious signs of corrosion.Due to the excellent lubrication properties of PTFE,the friction coefficient of the composite coating is reduced by approximately 75.22%compared to the EPN coating and the wear resistance is improved by a factor of 3.3.In addition,the composite coating exhibits a lower friction coefficient（0.046）and good wear resistance under corrosive media friction conditions due to the corrosion inhibition of the friction substrate by BTSA.