Nucleation and growth mechanisms of trivalent chromium conversion coatings on 2024-T3 aluminium alloy

Xavier Verdalet-Guardiola (1) , Benoit Fori (2) , Jean-Pierre Bonino (1) , Sandrine Nathalie Duluard (1) , Christine Blanc (1)

1 CIRIMAT - Centre interuniversitaire de recherche et d'ingenierie des matériaux
2 Mecaprotec Industries

Nucleation and growth mechanisms of trivalent chromium conversion coatings on 2024 aluminium alloy (AA 2024) were studied. Nucleation of 25 nm diameter nodules was observed on the ridges of the scalloped structure of degreased and desmutted AA 2024 after very short time of conversion treatment corresponding to the formation of a 12 nm thick precursor layer. Then, the composition of this layer evolved and concomitantly a chromium and zirconium outer layer deposited on top of it. Rather long-lasting anticorrosive properties were measured even for conversion coatings formed after short exposure to the conversion bath, except for the precursor layer.

Mots clés: A. Aluminium alloy; A. Copper; B. EIS; B. XPS; C. Trivalent chromium coating

Domaines: Matériaux

Xavier Verdalet-Guardiola, Benoit Fori, Jean-Pierre Bonino, Sandrine Nathalie Duluard, Christine Blanc. Nucleation and growth mechanisms of trivalent chromium conversion coatings on 2024-T3 aluminium alloy. Corrosion Science, 2019, 155, pp.109-120. ⟨10.1016/j.corsci.2019.04.035⟩. ⟨hal-02436678⟩