Electrochemical Corrosion Behaviour of Nano Aluminium - Polytetrafluoroethylene Pigment Modified Water borne Epoxy Coating on Carbon Steel

Abstract

For fasteners, corrosion causes rust on the threads, reduces their strength and making their disassembly difficult. The protective coating of fasteners needs to have excellent anti-corrosion and lubricating properties. In this paper, nano Aluminium (nano-Al) and Polytetrafluoroethylene (PTFE) particles were used to fabricate a nano Al-PTFE epoxy self-stratifying structure coating. The SEM, AFM, and DSC results show that the coating formed a self-stratifying structure when it is pre-dried at 110°C and then dried at 200°C. PTFE is located on the surface of the coating to enhance lubricity, while nano-Al is located at the bottom of the coating to enhance corrosion resistance. Moreover, Electrochemical impedance spectroscopy (EIS) shows that the Cdl of the nano Al-PTFE modified coating with an artificial defect is lower, while its Rct is higher than that of the other two coatings, indicating that corrosive electrochemical activity only occurred in a small area of the coating. The SVET results indicate that the distance of the nano Al-PTFE modified coating from the defect edge contour only changed a little after 48 h of immersion. In conclusion, the coating has good anti-corrosion performance.