Rust-busting scientists at work in Australia

A new scientific instrument that promises to reveal the secrets of corrosion could slash the cost of fixing rusty cars and even maintaining the Sydney Harbour Bridge.

Developed by CSIRO Sustainable Materials Engineering (CSME), the Scanning Kelvin Probe is a new generation instrument that reveals previously unobserved interactions taking place at the birth of corrosion.

"The instrument offers the kind of leap forward that astounded the science community when the first electron microscope was unveiled and revealed for the first time why metals deformed and fractured," says Aaron Neufeld, the CSIRO scientist behind the breakthrough.

"Observing this whole process is the key to developing new surface coatings that will mean structures such as the Sydney Harbour Bridge may need painting only once every 33 years instead of every 11 years," he says.

The potential cost savings for industry are huge. For example, in the aircraft industry a new corrosion resistant coating could save $3 million on a large commercial aircraft for each 10 year scheduled maintenance strip down.

"Corrosion is caused by the electrical interaction between metal and the atmosphere, a bit like the electricity produced with acid in a car battery. What is left from this process of corrosion is metal in the form of rust or the dusty material you can rub off an aluminium window frame," says Mr Neufeld.

"The Scanning Kelvin Probe can capture a picture of these electrochemical reactions within minutes compared to other instruments which take hours to collect data and then only from a small section of material.

"The Scanning Kelvin Probe is also the only analytical instrument that can provide information about electrochemical reactions and surface changes on coated metal products affected by thin films of moisture such as dew," he says.

Thin films of moisture resulting from humidity cycles are typically present in service environments for many metal-coated products. The effect of these environmental conditions can be simulated and studied using the Scanning Kelvin Probe.

"The sensitivity, speed and accuracy of the Scanning Kelvin Probe developed at CSME is close to the best that technology can provide," says Mr Neufeld.

"The development of the probe means CSIRO can now compete with much larger and better funded science teams in Europe and USA.

"CSIRO's secret is the way we managed to reduce the affect of noise interference on the operation of the Probe – but we can't divulge just how we achieved this to ensure the benefits of the breakthrough to Australia are not lost," he says.

Behind development of the Probe is the study of the electrochemical behaviour of galvanised steel and aluminium roofing and other metal-coated building products in infrastructure environments.

Current work includes an analysis of corrosion initiation due to salt particle deposition on zinc where new coatings or passivity treatments could extend the life of roofing materials and reduce the need for environmentally unfriendly chromate coatings.

The corrosion of zinc with salt particle deposits is recorded to assist the development of a realistic model to "see" this corrosion process and develop ways to beat it.

The results of this study have brought a revolutionary new understanding of how fast corrosion initiation proceeds and the chemical changes occurring on the surface of the zinc metal.

Results from studies using the Scanning Kelvin Probe built by CSIRO Sustainable Materials Engineering have created international interest in the scientific community and the performance of the instrument system has gained the attention of multinational instrument manufacturers.

Research and development continues at CSIRO to modify and improve the Probe instrument to be suited exclusively for materials and components used in the automobile and aerospace industry.

Further enquiries can be made via www.australia.org.nz

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