Corrosion-Wear Behavior of Polytetrafluoroethylene Reinforced Chemically Bonded Phosphate Ceramic Coatings

In order to effectively improve the corrosion-wear behavior and tribological properties of alumina chemically bonded phosphate ceramic coatings (CBPCs), polytetrafluoroethylene (PTFE) was used as the reinforcement to improve the corrosion-wear behavior and tribological properties of alumina CBPCs. CBPCs with different PTFE contents were prepared on the surface of A4 steel substrate by slurry method. The anti-corrosion property of CBPCs with different PTFE contents was tested by potentiodynamic dynamic polarization curve and electrochemical impedance spectroscopy (EIS). The tribological properties of CBPCs were analyzed by the comprehensive surface performance tester. The corrosion-wear morphology of alumina CBPCs was characterized by the super depth of field microscope. When the content of PTFE was 0.2%, alumina CBPCs had the best corrosion resistance, the corrosion current density of the alumina CBPCs decreased from 6.611×10⁻⁷ A/cm² to 6.29×10⁻⁸ A/cm², the corrosion potential of the alumina CBPCs increased from 2×10⁻³ V to 8.9×10⁻² V. The results showed that CBPC2 could hinder the permeation pathway of O₂ and Cl⁻, CBPC2 made the permeation more circuitous. H₂O had difficulty diffusing into corrosion pits, mainly depending on the formation of tortuous diffusion path and avoiding the galvanic corrosion between corrosive liquid and corrosion pits. Additionally, the influence of PTFE on friction and wear behavior of CBPCs under corrosive condition were clarified. CBPC2 could form oxidation film on the surface of the substrate easily, and the repair of oxidation film at cathode potential helped to reduce the friction coefficient. Cathodic polarization could decrease the friction coefficient of friction pair to 0.4 during corrosion-wear process. CBPC2 had the strong corrosion-wear deformation resistance to suppress the expansion of contact area, which caused the depth and wear rate of wear track decrease to 66.33 μm and 9×10⁻³ mm³/(N·m), respectively. Thus, the corrosion-wear behavior and tribological properties of alumina CBPCs were improved by mixing PTFE, the CBPC2 had great application prospects in materials protection.