CORROSION AND PROTECTION OF Al 6061 T6/Al_2O_3p IN MARINE ENVIRONMENT

摘要

Aluminium composites are technologically advanced materials with elevated physical mechanical properties. They can be considered an alternative to conventional aluminium alloys for offshore applications. In this work the behaviour of four different types of composites, having aluminium alloy 6061 T6 as matrix and aluminium particles as reinforcing, was studied. The composites were different in aluminium particle contents and in productive processes (i.e. casting or extrusion). Protective and an-tifouling properties of two new generation organic coatings (see Tab. 1) were also studied. Experimental tests consisted in electrochemical and free corrosion measurements after different immersion times in natural sea water. Electrochemical tests consisted in anodic and cathodic polarizations. Corrosion rate (after 2 hours of immersion) (see Tab. 2) and localized corrosion susceptibility (after 2 hours, 5 and 15 days of immersion) (see Tab. 3) were obtained. In particular corrosion current density (i_(corr)) and polarization resistance (R_D) showed a lower corrosive attack on samples containing more reinforcing phase.