Electrophoretic deposition of polytetrafluoroethylene (PTFE) as anti-corrosion coatings

Polytetrafluoroethylene (PTFE) is known as the 'king of plastics' because of its excellent resistance for both acid and alkali medium, so the coatings composed of PTFE have an attractive application prospect in the field of corrosion protection. In this work, with a solvent of ethanol containing 0.05 g center dot L-1 PEI + 0.1 mM nitric acid as the dispersion system, the PTFE coatings were successfully prepared onto the Mg-3Al-1Zn (AZ31) alloy sheets by electrophoretic deposition (EPD) strategy. The morphology of the electrophoretic PTFE coating was further reshaped through a sintering post-treatment at 380 degrees C in argon atmosphere. In 3.5 wt% NaCl solution, the corrosion current density was remarkably reduced (3.92 x 10-6 A center dot cm- 2 for the bare AZ31 vs 1.54 x 10-9 A center dot cm- 2 for the sintered PTFE coating AZ31), and the charge transfer resistance was significant increased (299.92 omega center dot cm2 for the bare AZ31 vs 2.79 x 106 omega center dot cm2 for the sintered PTFE coating AZ31), which means the electrophoretic-sintered PTFE coating can significantly improve the corrosion resistance of AZ31 alloys. More-over, it is also suggested that the electrophoretic-sintered PTFE coating may be a general anti-corrosion strategy for a series of metal materials.

Automated summary

PTFE coatings were successfully prepared by electrophoretic deposition (EPD) strategy using a dispersion system of ethanol containing 0.05 g/L PEI + 0.1 mM nitric acid. The morphology of the PTFE coating was improved through a sintering post-treatment. The electrophoretic-sintered PTFE coating significantly enhanced the corrosion resistance of AZ31 alloys by reducing the corrosion current density and increasing the charge transfer resistance. Moreover, it may serve as a general anti-corrosion strategy for various metal materials.