Graphene research points to environmentally friendly steel
Researchers at Tata Steel are hoping graphene could provide an environmentally friendly way to protect buildings from corrosion.
The company has partnered with the Engineering and Physical Sciences Research Council (EPSRC) to study whether graphene-based steel coatings could become an alternative to chrome and other potentially toxic chemicals that are increasingly restricted under EU law.
Tata has already established the ability of graphene, the super-strong, flexible form of carbon made from a single layer of atoms, to protect steel from corrosion but its researchers still don’t yet fully understand how it works.
Hans van der Weijde, breakthrough programmes manager for Tata Steel R&D, said he wanted to discover why graphene prevented corrosion beyond acting as a physical barrier to reactants such as oxygen.
‘In lab-scale trials we see a tremendous effect,’ he told The Engineer. ‘We know graphene has very good barrier properties. But even at levels where it has been used and doesn’t form a closed barrier you see improvements so there is more going on.’
The Tata team, who will work with UK universities on long-term research, postgraduate training and knowledge exchange, believe understanding graphene’s anti-corrosion properties will allow them to create flexible coatings that can protect steel for at least the 40 years of current premium products.
Part of the mystery around graphene comes from the fact that theoretically it should encourage steel to corrode faster but actually protects it, said John Collingham, surface engineering department manager at Tata Steel R&D.
When steel is coated with a metal such as zinc (a process known as galvanising), the electric potential between the two metals changes alters the corrosion reaction and the zinc is effectively sacrificed, corroding faster than the steel. Carbon’s properties mean it typically causes the steel to be sacrificed to corrosion, but in its graphene form it doesn’t.
‘Corrosion is a progressive, electro-chemical reaction and, for whatever reason, by using graphene we totally stabilise the reaction,’ said Collingham.
Other parts of the research will look at ways to use graphene’s high conductivity and possible transparency to improve products, and at how to manufacture graphene-based coatings, possibly using chemical vapour deposition whereby a gaseous form of carbon is deposited on a metal substrate.
Read more on UK engineers’ attempts to develop ways to mass-produce graphene.