AM60-AlN Nanocomposite and AM60 Alloy Corrosion Activity in Simulated Marine-Coastal Ambience

Abstract

The initial stages of AM60-AlN nanocomposite and AM60 corrosion behaviors were compared over 30 days of exposure to solution (NaCl, Na2SO4 and NaHCO3), simulating the marine-coastal environment (SME). The incorporation of AlN nanoparticles (1.0 wt.%) in the AM60 alloy matrix favored the lower roughness of the AM60-AlN, associated with the grain refinement in the matrix. During the immersion of the alloys, pH of the SME solution shifted to alkaline values >9, and therefore, the solubility of AlN aluminum hydroxide phases were raised, followed by a slightly higher release of Mg-ions and corrosion rate increase. The chloride ions attributed to the unstability of the Al-Mn phase and Al(OH)3 corrosion product was formed in a low content. The composite AM60-AlN presented lower value of the electrochemical noise resistance (Rn), suggesting that the corrosion process occurs with less difficulty. The localized corrosion near the Al-Mn cathodes seems to be stronger on the composite surface, in area and depth of penetration. The corrosion current fluctuations suggested that the corrosion is a weakly persistent process, dominated by the fractional Gaussian noise (fGn).