Replenishing the oxidation-induced Al-depletion in Cr2AlC MAX phase coatings
Year: 2026
Type: article
Abstract: Cr 2 AlC MAX phase coatings are known to form a protective alumina scale upon high temperature oxidation. Scale formation causes Al depletion, which results in the formation of Cr-carbides and pores that, in turn, cause coating failure. Here, we show that the oxidation-driven Al depletion of the coating is prevented by Al-replenishment using an Al-reservoir (Al-containing substrate), thereby extending the coating lifetime. Cr 2 AlC substrates with coarse and fine grain distributions were produced by spark plasma sintering and coated with Cr 2 AlC by magnetron sputtering. Upon oxidation at 1100 °C the Cr 2 AlC coatings, deposited onto a coarse-grained reservoir and onto MgO without an Al-reservoir, showed no significant change in Al content of the coating post-oxidation, and hence no evidence for Al-replenishment from the substrate. However, in the case of a Cr 2 AlC coating, deposited onto a fine-grained substrate, the Al content of the coating post-oxidation remained close to the initial concentration (∼23 at.%). This replenishment is rationalized by the presence of more grain boundaries in the fine-grained substrate, versus the coarse-grained one, enabling sufficient Al diffusion across the substrate/coating interface to offset the Al losses to the scale.
Source: Materials & Design
Language: English
Subfield: Materials Chemistry
Field: Materials Science
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $3,650
OpenAlex ID: W7162659584