According to the World Corrosion Organisation, corrosion causes $2.5Tr in damage to steel structures every year, representing between 3 and 4% of the annual gross domestic product of most industrialised countries.
Recently new primers containing zinc and other pigments have been introduced. These aim to fulfil the latest requirements for corrosion protection, as set out in an international standards document (ISO12944-2018), but unfortunately can also be highly toxic to acuatic life.
Users in marine environments are therefore increasingly demanding primers with a much reduced zinc content.
This is where graphene, a monlayer form of graphite, comes into play. Being a conductive material, graphen is able to favouralably influence the electochemical reaction that underlies corrosion, resulting in less rust.
Additionally, graphene can strengthen the adhesion of the binder in the coating system to the underlying substrate. This helps to prevent (salty) water from separarting this protective coating from its substrate.
Furthermore, graphene also enhances the ability of paint coatings to control pollutants. For example, a 15 litre pot of 'Graphenstone' is capable of absording 4.8kg of carbon dioxide. In addition, the product is antibacterial, anti-mould and anti-fungal.
Written by Satbir Gill, UK Bridges Board and London Technical Advisors Group Chairman
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Transportation Professional - January 2020