The effect of yttrium incorporation on the formation and properties of α-Al2O3 coatings

Abstract

The Al layer with α-Al2O3 seed crystals and the rare earth element Y were deposited directly onto a 316L stainless steel substrate and then oxidized at a temperature as low as 580°C using the double glow plasma technique. The complex Al target material containing 10 wt% α-Al2O3 seed crystals and 10 wt% Y was used in the experiment. The results indicated that the coatings were very dense and uniform. The field emission transmission electron microscopy observation indicated that element Y was discontinuously distributed, which was mainly concentrated at the grain boundary of the coating. After plasma oxidation, Y was oxidized to Y2O3. Under the action of coupled multiple factors (ion bombardment, α-Al2O3 seed crystals, and rare earth element Y), the AlYα oxide coatings contained large amounts of α-Al2O3 crystals. The increase of the Y content improved the adhesive force of the coatings. The corrosion current of the oxide coatings was reduced by three orders of magnitude.

Keywords

• α-al2o3 seed crystals
• double glow plasma technique
• rare earth elements