At first, pieces of steel coated with the varnish lasted only a few days when immersed continuously in the salt water. But by adjusting the concentration and dispersion of graphene within the composite, Banerjee and Dennis were able to get the varnish to hold up for a month.
Banerjee told Discovery News that he wants to include something in the coating that will detect a change in the pH level of water near where a scratch occurs, and react with the water in a way that would seal the crack.
While this technique is a long way from being commercialized, there's interest from some big players in the steel industry, notably Tata Steel, which has provided funding for Banerjee's experiments before. The two scientists also got a $50,000 grant from the New York State Pollution Prevention Institute. Banerjee said in a press release that the coating can be made with existing equipment at local steel plants.
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Unlike hexavalent chromium, which is used to coat bumpers and some engines, graphene isn't toxic, as it is just carbon. It also doesn't require strong acids to be applied. That's one reason the Pullution Prevention Institute is interested.