Corrosion Behavior of Shiny Side and Dull Side of Aluminum Foil in 0.3% Wt NaCl Non Agitated Solution: Appearance of Rhombus form Corrosion Morphology

Resumo

We have investigated the corrosion behavior of shiny and dull faces of aluminum household foil in 0.3 wt % NaCl nonagitated solution. The obtained results show several differences in the morphology and kinetic corrosion of the shiny and dull faces. After seven months of immersion in the 0.3 wt % NaCl non-agitated solution localized diamond-shaped corrosions appear in some zones of the aluminum foil. In the case of the dull face, their forms are very close to perfect rhombus; however the rhombus forms are swollen on the shiny face. In addition, we observe in other zones pitting corrosions. Rhombus form in the dull face is, probably, due to NaCl crystal precipitation on the marks left by the intermetallic particles, during the last passage of cold rolling causing a sheet-to-sheet contact. The adhesion component of friction increases the density of the marks on the dull surface and induces localized corrosion in the perfect rhombus form. However, the absence of a friction adhesion component provokes a deflection from the perfect rhombus form to a swollen rhombus form.