| dc.description | Rare earths (RE) have been used to improve the high temperature oxidation resistance of
chromium dioxide and alumina forming alloys. The RE are added either to the alloy or are
applied as a coating to the alloy???s surface. In this study, the sol-gel technique, well known to
produce fine grained ceramic oxides, was used to prepare nano-crystalline RE oxides of La,
Ce, Pd, Nd, Sm, Gd, Dy, Y, Er, and Yb. These oxides were used to coat Fe-20Cr specimens.
The cyclic oxidation resistance of the RE oxide coated specimens was determined. Marked
improvements were observed in the coated specimens and the extent of improvement
depended on the nature of the RE oxide, its ionic radius and other features of the coating.
Extended oxidation tests were carried out with La2O3 and Pr2O3 coated Fe-20Cr alloy. In these
tests the specimens were heated to different peak temperatures and cooled at rates of up to
1000C/s. The La2O3 coatings were more effective in increasing cyclic oxidation resistance
compared to Pr2O3 coatings. The role of RE in increasing overall oxidation resistance of
chromium dioxide forming alloys is discussed. | |
