An electrochemical and SEM study of the mechanism of formation, morphology, and composition of titanium or zirconium fluoride-based coatings

Abstract

International audienceElectrochemical rest potential and cyclic voltametry were used to investigate the behaviour of the 6% Al magnesium alloy AM60 in various zirconium or titanium fluoride aqueous acid solutions. These solutions have a wide range of aggressiveness with respect to AM60 due largely to fluoride concentration and in some cases to their highly acidic nature. The morphology and composition of the resulting film have been determined by Scanning Electron Microscopy (SEM), and Energy Dispersive X-ray spectroscopy (EDX). The film nucleation is promoted by a pH increase due to water reduction and is thus more likely to occur on the cathodic parts of the surface. Correlatively, film formation on the anodic primary solid solution occurred in only one solution

Application of artificial neural network and adaptive neuro-fuzzy inference system to investigate corrosion rate of zirconium-based nano-ceramic layer on galvanized steel in 3.5% NaCl solution

“…On the other hand the clustering of Zirconium species on the surface in more concentrated solutions produces a non-uniform surface containing a lot of cracks and defects. This effect had been observed previously on magnesium surface [37,38].…”

Review—Conversion Coatings Based on Zirconium and/or Titanium

“…38,58,71,74,102,105,106 After sufficient immersion time (Figs. 3 and 4) the coating covers the surface uniformly on Al alloys, 69,81,107,112 HDG steel, 52,68,72 and CRS.…”

Formation and characterization of Fe3+-/Cu2+-modified zirconium oxide conversion layers on zinc alloy coated steel sheets

“…The most interesting candidates for these sophisticated surface coatings are organosilanes [2][3][4][5][6], lighter rare earth metals [7,8] and transitional metals [9], respectively. Moreover, promising alternatives are the application of zirconium containing layers on the metal surface by the solgel process [10][11][12][13] or by immersion in hexafluorozirconic acid (H 2 ZrF 6 ) conversion solution [14][15][16][17][18][19][20][21][22][23][24].…”

“…Surprisingly, despite the high technological importance of this substrate material, the number of reports in this area is significantly smaller compared to those using other metallic substrates such as magnesium [22,27] or aluminium alloys [14,17]. Several groups investigated environmentally friendly conversion layers by means of different surface analytical and electrochemical methods using commercial solutions, with more or less unknown chemical composition [20,21,23,24,28,29].…”