Chromate and Chromate–Phosphate Conversion Coatings on Aluminium

Abstract

Investigations of chromate and chromate-phosphate conversion coatings on aluminium using SIMS and AES techniques revealed that they are composed of hydrated chromium oxide/hydroxide and chromium phosphate respectively. These compositions are consistent with the electrochemical mechanism for conversion coating formation on aluminium. Enrichment of the outermost regions of the coatings with coating solution species suggests the gradual migration of these species under a concentration gradient towards the metal/coating interface where coating formation and growth consume such species.

Permanganate - Based Hybrid Nano-Conversion Coating on Aluminium

“…On surface value, this implied formation and development of coatings in the conversion coating bath. The formation and development of permanganate coating on aluminium probably followed "the substrate activation/coating materials deposition" model reported for chromate conversion coatings [12][13][14][15] which will involve the activation of aluminum by fluoride species in solution thus,…”