Self-Healing Coating Could Extend Corrosion Protection for Steel

Researchers at the University of Queensland (UQ) are developing a self-healing coating that could extend the service life of steel in buildings, bridges, vehicles and other applications. The technology combines water-based paint with nanoparticles that release corrosion inhibitors when local conditions change.

According to UQ, electrochemical testing indicates that the coating could slow corrosion by more than 600 times compared with many existing high-performance products. The technology remains under development, with pilot-scale testing planned.

Nanocontainers Respond to Corrosion

Dr Asep Nugraha and colleagues at UQ’s Australian Institute for Bioengineering and Nanotechnology (AIBN) developed powder-like particles that act as tiny storage containers. These particles hold benzotriazole, a commonly used corrosion inhibitor, within an engineered nanostructure.

When added to waterborne polyurethane, the particles create a coating that responds to changes in local acidity or alkalinity. Corrosive conditions trigger the release of the inhibitor, helping to protect exposed steel at damaged areas.

The research, published in Small Science, describes nanocontainers based on a metal-organic framework with an outer silica shell. This shell improves their structural stability and compatibility with the waterborne coating. The self-healing mechanism restores corrosion protection at damaged sites through controlled inhibitor release.

Laboratory Results Show Potential

Electrochemical testing indicated a corrosion rate of approximately 37 nanometres per year. UQ compares this with the reported rate of 0.025 millimetres per year for many high-performance corrosion-protection products.

The published study also assessed the coating during 39 days of immersion in a salt solution. These laboratory findings support further development, although they do not establish a century-long service life under real-world conditions.

Nugraha suggests that the technology could eventually enable much longer intervals between applications. His example of protecting Brisbane’s Story Bridge for more than 100 years illustrates that ambition, rather than a demonstrated lifespan.

Longer Protection, Less Maintenance

For architects, product designers and automotive designers, the coating offers a potential route to more durable steel components. Extending corrosion protection could reduce repainting, maintenance and premature replacement, helping to retain materials in use for longer.

This could be particularly valuable for bridges and other infrastructure, where surface preparation and coating application require substantial time and expenditure. The Australasian Corrosion Association estimates that corrosion costs Australia around A$90 billion annually across sectors including infrastructure, water, defence, and oil and gas.

The team aims to develop a commercial product within five years. Professors Yusuke Yamauchi and Nasim Amiralian oversaw the project, with contributions from PhD scholar Kwang Keat Leong and support from Australian fabrication and microscopy facilities.

Source & photo: The University of Queensland