Fabrication and high temperature oxidation resistance of ZrO2/Al2O3 micro-laminated coatings on stainless steel

ZrO2/Al2O3 micro-laminated coatings have been successfully fabricated on stainless steel by electrolytic deposition and an oven drying process alternately. Microwave sintering under pressure was subsequently employed to obtain the final composite coatings. The as-prepared ZrO2/Al2O3 coatings were characterized by high-resolution field emission scanning electron microscopy (FE-SEM) and XRD. The results indicated that the coatings had alternate six layers of ZrO2 and Al2O3 with nano/micro-structures. The phase composition of the coating was t-ZrO2, α-Al2O3 and θ-Al2O3. High temperature cyclic oxidation test at 900 °C in air for 200 h was also adopted to investigate the oxidation resistance of such coatings on stainless steel. The results revealed that ZrO2/Al2O3 micro-laminated coatings improved the oxidation and spallation resistance of stainless steel substrate significantly and such effect was related to the stepped oxygen diffusion suppression of multi-sealed Al2O3 layers, selective oxidation of Cr and good mechanical properties induced by ZrO2/Al2O3 micro-laminated structures.