Preparation And Corrosion Properties Of Polytetrafluoroethylene Coating And Coating Of Epoxy Soybean Oil Resin

Metal corrosion is ubiquitous,which will bring huge economic losses and safety problems.Therefore,it is necessary to study metal corrosion prevention measures.At present,the research and application of coating anticorrosion on metal surfaces at home and abroad are relatively extensive.In this thesis,anticorrosion research were carried out by preparing new functional material coatings.Polytetrafluoroethylene coating and epoxy soybean oil resin coatings were prepared on a 20#carbon steel substrate.Through field emission scanning electron microscope,Fourier infrared transform spectrometer,X-ray diffractometer,X-ray energy spectrometer,Thermogravimetric analyzer,Static contact angle measuring instrument,Coating thickness gauge,Nano-indentation instrument,Electrochemical impedance spectroscopy,Equivalent circuit fitting characterizes the micro-morphology,chemical composition,thermal stability,hydrophobicity,coating thickness,hardness,elastic modulus and corrosion resistance of the coating.The specific research contents and results are as follows:Using 20#carbon steel material as the substrate,after the phosphating pretreatment,a hydrophobic PTFE coating with a thickness of（13±2）μm was prepared on the phosphating carbon steel by dipping and pulling method.The results show that the size of the phosphating particles on the surface of the ordinary phosphating carbon steel is relatively coarse and uneven,while the size of the phosphating particles on the surface of the phosphating carbon steel using magnetic stirring is small and dense,and the crystal size is smaller than that of the ordinary phosphating.The prepared phosphating film is composed of Zn₃（PO₄）₂·4H₂O,Zn₂Fe（PO₄）₂·4H₂O and Mn₂Zn（PO₄）₂·4H2O.Among them,Zn₂Fe（PO₄）₂·4H₂O is the main component.The main components of the PTFE coating are PTFE and a small amount of TFE.Through EIS analysis and equivalent circuit fitting,we can obtain that the PTFE-coated carbon steel sample exhibits good corrosion resistance in 3.5wt%Na Cl solution.When immersed for 5 days,the corrosion resistance of the coating was almost lost.In order to prepare anticorrosive coatings with long-term corrosion resistance,this thesis uses epoxy soybean oil as the main raw material and tetraethylene pentamine as the curing agent to prepare epoxy resins with different molar ratios on the surface of20#carbon steel substrate.The results show that the thickness of the epoxy soybean oleoresin coating is between 45μm and 48μm.As the content of epoxy soybean oil in the raw material increases,the hardness,elastic modulus,water resistance and corrosion resistance of the epoxy soybean oil resin coating are enhanced.Electrochemical impedance spectroscopy and fitted equivalent circuit analysis show that when the molar ratio of tetraethylenepentamine epoxy soybean oil is 2,the coating resistance R_c of the epoxy soybean resin coating reaches 8.22×10¹¹Ω·cm²,charge transfer resistance R_ctreaches 1.32×10¹⁰Ω·cm²;when immersed in 3.5 wt%Na Cl solution for 30 days,R_c is2.57×10⁹Ω·cm²,R_ct reaches 3.17×10⁹Ω·cm² which the coating shows excellent long-term anti-corrosion performance.The above research provides a new possible way for the selection of corrosion-resistant coating materials.