Formation of a metastable nanostructured mullite during Plasma Electrolytic Oxidation of aluminium in “soft” regime condition

This paper demonstrates the possibility of producing a lamellar ceramic nanocomposite at the top-most surface of oxide coatings grown with the Plasma Electrolytic Oxidation process (PEO). PEO was conducted on aluminium in a silicate-rich electrolyte under the so-called “soft” regime. Nanoscale characterisation showed that the transition from the “arcs” to the “soft” regime was concomitant with the gradual formation of a 1:1 mullite/alumina...