Synergistic Effects of Epoxy/PTFE/CNT Hybrid Nanocomposite Coating Against Silica Scaling and Corrosion Under Varying Geothermal Flow Conditions

This study presents the development of a multifunctional epoxy/polytetrafluoroethylene (PTFE)/carbon nanotube (CNT) hybrid nanocomposite coating designed to mitigate localized corrosion and silica scaling in harsh geothermal environments. Morphological and mechanical evaluations identified an optimal formulation (epoxy/PTFE40/CNT0.8) that successfully balances surface hydrophobicity (water contact angle of 139°) with superior adhesion strength (8.685 MPa), avoiding the nanoparticle agglomeration and structural defects observed at excessive filler loadings. Thermal analysis demonstrated that the integrated CNT network acts as a physical diffusion barrier, modifying the matrix degradation into a stabilized two-stage process capable of withstanding continuous exposure up to 150°C. Electrochemically, the optimized composite established a highly tortuous barrier against corrosive Cl- ions, achieving a 94.05% protection efficiency and suppressing the corrosion rate to 0.0098 mm/year. Furthermore, the tailored micro-topography successfully prevented the mechanical interlocking of mineral deposits, delivering peak silica scaling reductions of 65.08% under hot geothermal conditions and maintaining a 50.92% mitigation efficacy during extreme cold supersaturation. Ultimately, this synergistic hybrid coating offers a robust, highly prospective strategy for simultaneously combating dual degradation threats and extending the operational lifespan of geothermal infrastructure.