Corrosion resistance of Al2O3+ZrO2 composite coatings sprayed on stainless steel substrates

Composite thermal barrier coatings (TBCs) of Al₂O₃+ZrO₂ were deposited on SUS304 substrates by gas tunnel type plasma spraying. A common-used potentiostatic anodic polarization test procedure was used to measure the corrosion characteristics of the coatings. The coatings prepared with different Al₂O₃+ZrO₂ mixing ratios and different thicknesses were compared for corrosion resistance. The corrosion potential and deactivated corrosion current density obtained from the coatings were related to the coating microstructure. The results show that the higher alumina content and the thicker the coatings, the better the corrosion resistance, which is attributed to the resistance of coatings. The coating porosity and thickness played the important roles on the corrosion behavior of Al₂O₃+ZrO₂ coated SUS304 substrate.