Effect of yttria(Y2O3) coating for high temperature oxidation resistance of 9Cr-1Mo steel

Abstract

This paper investigates the effect of yttria (Y₂O₃) coating on high temperature oxidation behaviour of low alloy 9 Cr–1Mo steel. The superficial coating is Y₂O₃ was prepared for experimental investigation. The isothermal corrosion study of uncoated and coated specimens was carried out in air oxidation environment at 973 K for 8 h. The corrosion rate and reaction kinetics were studied and the post corroded scales were characterized in SEM, EDS and XRD. The results clearly indicate that Y₂O₃ coated specimen improves the high temperature oxidation resistance than uncoated specimens. The improvement of oxidation resistance in presence of Y₂O₃ coating can be attributed to the changed mechanism of scale growth from outer cation migration to inner anion migration and enhancement of scale adhesion with the substrate. Further, enhancement of scale adhesion with the substrate in case of Y₂O₃ coating also improves the oxidation resistance. The detail mechanism of the oxidation of Y₂O₃ coated and uncoated specimen is further discussed in this paper.