Alternative conversion coatings to chromate for the protection of magnesium alloys

S. Pommiers , Jérôme Frayret (1) , Alain Castetbon (2) , Martine Potin-Gautier (1)

1 IPREM - Institut des sciences analytiques et de physico-chimie pour l'environnement et les materiaux
2 LCABIE - Laboratoire de Chimie Analytique Bio-Inorganique et Environnement

Chromium Conversion Coatings (CCCs) are widely used for the protection of magnesium alloys against the corrosion but this approach is limited due to the toxicity of hexavalent chromium. Alternative conversion coatings are based on solutions containing chromium (III), permanganate, phosphates, Rare Earth Elements (REEs) or vanadium. This review details the deposition and protection mechanisms of CCC technology and other promising processes. Permanganate/phosphate-based coating presents a corrosion resistance equivalent to CCC and REEs have self-healing properties but no coating present all the properties of CCCs. The development of new non-toxic conversion coatings remains a priority

Domaines: Chimie analytique

S. Pommiers, Jérôme Frayret, Alain Castetbon, Martine Potin-Gautier. Alternative conversion coatings to chromate for the protection of magnesium alloys. Corrosion Science, 2014, 84, pp.135-146. ⟨10.1016/j.corsci.2014.03.021⟩. ⟨hal-01561255⟩