Corrosion inhibition of aluminium alloys by molybdate ions: A critical review of the chemistry, mechanisms and applications

Molybdate anions are used as an individual inhibitor or in mixed synergistic combinations added directly to the solution, incorporated as fillers, pigments or nanocontainers into various coatings (sol-gel, anodised, plasma electrolytic, organic and layer double hydroxide coatings), as an agent in pre-treatments or post-treatments or as individual conversion coatings prepared to be exposed to aggressive media. The review addresses the action of molybdate on aluminium alloys in each of these applications. The general chemical characteristics of molybdenum are described with a particular emphasis on aqueous chemistry and the formation of monomer and polynuclear species.