High temperature oxidation behaviour of yttria (Y_2O_3) coated low alloy steel

摘要

This paper investigates the effect of yttria (Y_2O_3) coating on high temperature oxidation behaviour of low alloy 2.25Cr-1Mo steel. The superficial coating is Y_2O_3, which 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 characterised by SEM, Energy-dispersive X-ray spectroscopy and X-ray diffraction. The results clearly indicate that Y_2O_3 coated specimen improves the high temperature oxidation resistance than uncoated specimen. The improvement of oxidation resistance in presence of Y_2O_3 coating can be attributed to the modification of grain structure of the scale, changed mechanism of scale growth and enhancement of scale adhesion with the substrate. The detailed mechanism of the oxidation of Y_2O_3 coated and uncoated specimen is further discussed in this paper.