Influence of surface preparation on performance of chromate conversion coatings on Alclad 2024 aluminium alloy

Corrosion behaviour of a 2219 aluminium alloy treated with a chromate conversion coating exposed to a 3.5% NaCl solution

“…This is in agreement with the results of Juffs [13] and Campestrini [14]. The Auger electron spectra in Figure 2 (a) and (b) indicate that Cu is incorporated into the chromate layer on the intermetallic, in agreement with the results of Liu et al [15].…”

“…They observed that the coating on the matrix was 10 times thicker than the coating on the intermetallic phase. Campestrini et al [14] observed that the nucleation of the coating occurs at the second phase precipitates. The intermetallics represent cathodic sites on the matrix, enhancing the rate of the reduction of the chromate species.…”

“…The intermetallics represent cathodic sites on the matrix, enhancing the rate of the reduction of the chromate species. Furthermore, Campestrini et al noted that the aluminium oxide in the proximity of the intermetallics is known to contain more flaws and defects thus is more easily attacked by the fluoride present in the bath and electron tunnelling is then promoted [14]. After a few seconds the intermetallics are completely coated, consequently they become less reactive and the reduction and deposition of chromium continues in other areas.…”

“…After a few seconds the intermetallics are completely coated, consequently they become less reactive and the reduction and deposition of chromium continues in other areas. As a consequence the layer formed is discontinuous with a large number of defects, mainly in proximity of the precipitates, with the result that it is less protective [14].…”

Correlação entre microestrutura e comportamento de corrosão em duas ligas do sistema Al-Fe-Si produzidas pelos processos industriais de lingotamento contínuo e semi-contínuo.

“…Os elementos mais comumente encontrados como impurezas no alumínio não ligado ou comercialmente puro, série 1XXX, são o ferro (Fe) e silício (Si) em maior ou menor grau, dependendo do nível de pureza do material (HATCH, 1984;CAMPESTRINI, 2001a; REBOUL e BAROUX, 2011).…”