Researchers at the University of Queensland’s Australian Institute for Bioengineering and Nanotechnology (AIBN) have developed a self-repairing coating designed to extend the lifespan of rust protection on steel used in infrastructure, vehicles and other applications.
The coating uses powder-like particles that can be added to water-based paint to create a corrosion barrier capable of responding to damage. According to AIBN, electrochemical testing indicates the coating could restrict corrosion to 37 nanometres per year, representing a more than 600-fold improvement compared with high-performance coatings that report corrosion rates of 0.025 millimetres per year.
AIBN nanoarchitect Dr Asep Nugraha said the particles functioned as small containers that release rust-inhibiting molecules when required.
“All rust-proof coatings inevitably wear and tear with time, there is no stopping that,” Dr Nugraha said.
“What we have created is a barrier that is constantly sensing if something is wrong so it can patch any scrapes and cracks itself, greatly extending the duration of protection.”
The technology encases the commonly used rust inhibitor benzotriazole in a nanostructure. When incorporated into waterborne polyurethane coatings, the resulting composite responds to changes in acidity, triggering the release of the corrosion-inhibiting material.
“Each tiny particle is basically a nanocontainer that releases repair molecules only when the conditions demand it,” Dr Nugraha said.
AIBN said the potential application of the technology comes amid significant costs associated with corrosion. The Australasian Corrosion Association estimates rust has an annual impact of about $90 billion across Australia’s oil and gas, water and wastewater, infrastructure and defence industries.
Dr Nugraha said extending coating lifespans could reduce the maintenance required for public assets such as bridges.
“For structures like bridges, applying a rust-proof coating comes at a great effort and cost, often to the public,” he said.
“It is not a coating that will last forever, but coatings that contain our technology will have a greatly expanded lifetime, meaning far less maintenance, and a much longer time between applications.”
The research has also involved AIBN PhD scholar Kwang Keat Leong, whose work focuses on controlling the growth of metal-organic framework crystals using nanocellulose derived from plants.
AIBN said Leong’s research found that metal-organic frameworks grown on nanocellulose could hold three times more corrosion inhibitors, while the resulting coating provided up to five times greater corrosion protection.
The researchers are now planning pilot-scale testing, with the aim of developing the technology into a commercial product within five years.
“Nanoarchitects work at an extremely small scale to build things that often defy what is physically possible,” Dr Nugraha said.
