Characterizations of Cladded 6082-T6 Aluminum Alloy Through Hard Anodizing

Abstract

Aluminum alloys have attractions to be used for a wide range of applications. Although the passive film on aluminum can provide corrosion protection, it has limited wear resistance in oil and gas applications due to the aggressive environment. This work has investigated the enhancements of hard anodizing on the performance of 6082-T6 aluminum alloy surface against erosion and corrosion test environments. The study investigates the surface roughness and hardness of the hard-anodized coating before going deeper in the cross-section to study in details the macro/microstructure of the formed layer. The erosion resistance of the coated layer, in particular, the effect of sand concentration and temperature variations to the aqueous slurry impingement against material properties such as adhesion, ductility, and roughness were investigated. In addition, a series of electrochemistry tests have been conducted to verify the corrosion performance. As a reference, the un-coated aluminum substrate was instigated in all the experiments. The resulted hard anodized coating layer had good adhesion with the aluminum substrate and was consisted of two distinct amorphous sub-layers of almost 50 m thick with some elongated porosity. It has been shown that the erosion resistance of aluminum alloy can be highly improved by hard anodizing, especially at high temperature. The hard-anodized sample shows almost twice hardness values compared with aluminum substrate for both eroded and un-eroded conditions. For the corrosion behavior, the hard-anodizing coating has lower corrosion current density than the aluminum substrate.