Effect of Fluoride Addition in Sulfuric Acid-Based Desmutting Solution for Aluminium Alloy AA8006

Aluminium alloys are covered spontaneously by a natural oxide layer, well adherent to the surface. For improving the material’s anticorrosion performance surface pre-treatments are needed in order to remove the superficial oxide and to prepare the alloy surface to subsequent treatments. The pre-treatment process involves several steps, including desmutting. The last requires the immersion of the part in an appropriate solution, typically composed of several chemicals, able to remove the oxide layer. In this work, the effect of the fluorides addition into a sulfuric acid-based solution, when used in a desmutting industrial process, was evaluated. Potentiodynamic curves, glow discharge optical emission spectrometry and contact angle techniques were used to characterize the surface of the aluminium alloy AA8006 after desmutting.