Role of Cerium in Stabilizing Corrosion and Oxidation of Inconel 625

Inconel 625 is a nickel-based superalloy that is extensively employed in marine, energy,

aerospace, and chemical processing industries as it possesses a good mechanical strength and resistance to

corrosion and oxidation. However, the service performance is typically constrained by surface-controlled

degradation processes and not bulk material failure on a long-time basis. Localized corrosion in chloridebearing conditions, oxide scale and instability during high-temperature loading, and corrosion-wear

synergy under combined mechanical and chemical loading are the major issues that control the life of

components. In recent years, cerium and cerium oxide have been shown to be promising new surface

modifiers as they can function not just to resist but to actively control corrosion and oxidation processes

by the use of passive barrier coating. The paper is a review of cerium-modified Inconel 625 surfaces in

this paper with a detailed mechanism orientation, focusing on corrosion behaviour, oxide scale

stabilization, and degradation synergy. The dynamic nature of cerium as a chemical regulator is critically

examined, as well as cerium role in stabilizing passive films, inhibiting localized corrosion, enhancing the

adhesion of oxide scales, and alleviating corrosion-wear interaction. This review by comparative

synthesis of degradation behaviour shows that using cerium essentially transforms progressive

degradation into a more directed and self-adaptive process, through its fundamental change of pathways

to surface reactions. The presented insights can be taken as a strong framework to develop long-term

surface engineering solutions to Inconel 625 working in harsh and varied service conditions.