Oxidation behviour of sol-gel zirconia coated 9Cr-1Mo ferritic steel in air atmosphere

Abstract

The oxidation behaviour of sol-gel derived zirconia coated 9Cr-1Mo ferritic steel has been examined at 700-900°C in air atmosphere. X-ray elemental mapping of the coated surface detected a continuous band of zirconium and oxygen, attributing to the presence of zirconia coating of around 2 µm in thickness. Oxidation kinetics indicates that the oxidation rate constant of the coated substrates decreases an order of magnitude lower as compared to uncoated substrates. Measurement of a noticeable increase in activation energy of the coated surface is further evidence towards the improvement of the oxidation resistance of the steel after coating development. Microstructural examination through field emission scanning microscope (FE-SEM) of the oxidized substrates show the presence of comparatively thin, less porous and compact scale at the coated surface than uncoated surface.