Experimental and mechanism studies on high CaCO3 fouling inhibition of PTFE coating with enhanced stability and anti-corrosion

Surface coatings are an effective technique for mitigating fouling in heat exchangers. In this study, a stable polytetrafluoroethylene (PTFE) coating was prepared with improved corrosion resistance and CaCO3 fouling inhibition rate. The prepared PTFE coating remains strongly stable even undergoing tape stripping, sandpaper abrasion, water impacting and immersion. The corrosion-suppression efficiency of the coating is 95.09 % compared to the stainless steel surface. Fouling tests reveal that the coating possesses an inhibition rate of 86.25 %, and it retains a high level of fouling inhibition rate even after 100 cycles of tape stripping and 400 mm of sandpaper abrasion. Additionally, molecular dynamics simulation was performed to gain insight into the anti-fouling mechanism of the PTFE coating. The results demonstrate the presence of two dense adsorption layers of water molecules in close proximity to the metal surface, which is found to be a crucial role in facilitating the adsorption of CaCO3 ions due to their strong attraction (Einteraction=-15.47 eV) towards the ions. In contrast, the weaker interaction (Einteraction=-1.52 eV) between PTFE and water molecules results in the absence of dense water adsorption layers on the PTFE coating. Consequently, the PTFE coating effectively reduces the rate of ion adsorption on the metal surfaces in the initial stage of CaCO3 fouling formation.