Preparation Of Solid-liquid Micro-nanoscale Composite Coating System And Its Anticorrosion Property

Polypyrrole (PPy) as a typical intrinsically conductive polymer not only has excellent conductivity which can be up to103S/cm in doped state, but also has a good property of reversibility electrochemical doping and dedoping and extraordinary environmental stability resistance. Furthermore, it has been caused widely researched based on its microstructures of particle morphology. More than30years of wordwide intense research and huge efforts, poly (3,4-dioxythiophene)(PEDOT) has attracted wide interest due to its great performace including excellent environmental stability and high electrical conductivity (and the conductivity of its nanotube composites can be up to about2×103S/cm), and it has been of particular significance because of its potential applications in antistatic materials, super capacitors, electrochromic devices, organic light emitting diodes, the biological sensors based on the advantages of non-toxicity, excellent electrical conductivity, good environmental compatibility, ease of synthesis and reprocessing. In previous work, it was found that the traditional epoxy paint mixed with a small amount of commercial poly (3,4-ethylenedioxy thiophene)/poly (styrene sulfonate) and preservative additive of polyethylene glycol could significantly reduce the occurrence of pitting corrosion and improve the mechanical properties of the coating. However, there were few reports on PEDOT film for studying as anti-corrosion coating materials. In recent years, Aizenberg and coworkers have reported a new style of composite material with the slippery liquid-infused porous surface (SLIPS), which was inspired by Nepenthes plant in nature. The preparation processes of this composite material were as follows:firstly, a micro/nanoscale rough surface was successfully fabricated in the metal surface. After that, the as-formed rough surface was been modified by the fluoride agent so that a strongly hydrophobic surface having high affinity to oil is obtained. Lubricant fluid was externally injected onto the porous surface. SLIPS showed extremely excellent performances of self-healing, anti-icing, and anti-frosting. Nowadays, there is no research about the anti-corrosion performance of the complex phase system. The thesis mainly focused on the preparation and the anticorrosion mechanism of metal based on conducting polymer or the complex phase syeterm injected lubricant fluid.(1) PPy/LS system which has a high surface roughness was obtained by electrochemical synthesized in the low alloy steel surfaces (921A) at high deposition potentials. Different characterization methods including X-ray diffraction infrared spectroscopy, scanning electron microscopy, etc. were used to study the microscopic surface structure and physical-chemical properties of the internal structure of the PPy film. It was found that the PPy film with a rough surface was similar to the "pitcher" structure.(2) The as-formed rough surface was been modified by the fluoride agent and the porous surface injected with lubricant fluid. For the long term corrosion protection from PFL/PPy, open circuit potential and optical microscopy were used to monitor the corrosion state from the3.5wt.%NaCl medium. Potentiodynamic polarization was used to study the anticorrosion performance of the complex phase system. It was found that the PPy/LS could effectively improve the anticorrosion of metals, and the PFL/PPy/LS have the best performance of the anticorrosion for a long time.(3) SEM, XRD, FTIR were used to investigate the surface morphology and internal structure PEDOT which was electrochemical polymerization at the constant potential. The anticorrosion performance of stainless steel, PEDOT/stainless steel, lubricant fluid/PEDOT/stainless steel in acidic, neutral and alkaline solution were systematically studied by potentiodynamic polarization, electrochemical impedance spectroscopy and the surface morphology observation. It was discussed the anticorrosion mechanism of SS, PEDOT/SS and PFL/PEDOT/SS in detail and found that the PFL/PEDOT/SS system had a better anticorrosion property in the alkaline solution.