Advances in understanding the initial stages of biomineralisation on AlMg 5083 aluminium alloy in a marine environment: Influence of microbial activity and polarisation

Abstract

This paper investigates the role of microbial activity and polarisation on the first stages of biomineralisation on aluminium alloy 5083 in marine environment. The experiments were carried out in seawater seeded with salt marsh sediments as microbial inoculum. Microbial colonisation was observed on the surface after 10 days immersion at the open circuit potential (OCP). For the first time, the catalysis of dioxygen reduction by marine microbial activity was demonstrated on Al alloy using linear sweep voltammetry. This biocatalytic effect also influenced the corrosion rate (polarisation resistance measurement) and the formation of the biomineralization layer. Surface and cross-section SEM observations showed the existence of this layer, its mass was measured by phospho-chromic stripping. At the OCP, after 10 days' immersion, the layer is 31 % heavier in the presence of microorganisms, demonstrating the involvement of microbial activity in its formation. To understand the mechanism involved, the application of different polarisation potentials highlighted the role of cathodic and anodic reactions, showing that a dissolution/precipitation phenomenon was at the origin of the formation of the mine-ralised layer.