Anticorrosion and Scale Behaviors of Nanostructured ZrO₂–TiO₂Coatings in Simulated Geothermal Water

Abstract

Corrosion and scaling phenomena often appear simultaneously and act synergistically in geothermal water system. We prepared the nano-ZrO2–TiO2 composite coatings on the AISI type 304 stainless steel with the chemical liquid phase deposition method. Surface morphology, crystal form, and chemical elements of the coatings were investigated with field emission scanning electron microscopy, energy-dispersive X-ray spectroscopy analyzer, X-ray diffraction, and thermal gravimetric/differential thermal analyses instruments, respectively. Corrosion behaviors and scale properties were tested by potentiodynamic polarization and electrochemical impedance spectroscopy measurements in the simulated geothermal water at 50 °C. The results reveal that the anticorrosion performance of the ZrO2–TiO2 composite coating is markedly improved compared to the austenitic stainless steels. A pitting corrosion and scale deposition mechanism was proposed for the ZrO2–TiO2 composite coating in the simulated geothermal water. These findings have potential implication for the protection of the austenitic stainless steel against the geothermal water corrosion.