Investigation of the role of oxide scale on Stellite 21 modified with yttrium in resisting wear at elevated temperatures

Wear damage caused by sliding contact between metallic components at elevated temperatures during service is a common problem for many mechanical systems. Considerable efforts have been made to reduce such type of wear damage. Recent studies demonstrated that the modification of metallic materials by alloying with oxygen-active elements, such as yttrium, was effective to diminish high-temperature wear. Such improvement in the high-temperature wear resistance by alloying yttrium could benefit from the enhanced oxidation resistance as well as a strengthened oxide film with higher adherence to the substrate. It is logical to expect that a strengthened oxide scale can help to bear the contact stress force, thus further reduce wear. However, how a thin oxide scale can effectively reduce wear is not well evaluated and understood. Clarification of this issue is the objective of this research.