Advanced corrosion resistance and mechanistic insights of electroless Ni-P-PTFE coatings on L245NS substrate in H2S-saturated environments
The extraction and transportation of oil and gas pose significant challenges due to corrosive environments, particularly hydrogen sulfide (H 2 S) exposure. This study investigates the use of polytetrafluoroethylene (PTFE) to enhance the corrosion resistance of nickel‑phosphorus (Ni P) coatings in H 2 S-rich environments. Electroless deposition was employed to prepare Ni-P/PTFE coatings, which were then subjected to simulated H 2 S corrosion tests. Results indicate that the incorporation of PTFE led to a more uniform Ni P coating with reduced porosity, significantly improving corrosion resistance. The coatings exhibited enhanced protective performance by stabilizing corrosion product layers and preventing the formation of corrosion channels. Ni-P-PTFE coatings overcame the existing research challenge of Ni P coatings' corrosion in H2S environments, showing no penetration of the corrosive medium into the substrate after 720 h of immersion. The corrosion rate of the coating is only 0.0261 mm/year, only 4.27 % of the corrosion rate of the L245NS substrate in the early stage of corrosion. Moreover, after characterization by SEM, XRD and XPS, it was found that the presence of PTFE altered the corrosion mechanism, promoting the formation of stable nickel sulfide and oxide layers on the surface. This study sheds light on the mechanisms underlying PTFE-enhanced corrosion resistance in Ni P coatings, offering promising implications for extending the lifespan of equipment in the oil and gas industry.
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