Probe Promises Corrosion Revolution

A scientific instrument that promises to reveal the secrets of corrosion could cut the cost of fixing rusty cars or 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. Observing the process is the key to developing new surface coatings that will mean structures may need painting only once every 33 years instead of every 11 years.

Potential applications include the aircraft industry where a corrosion resistant coating could save $3 million on a large commercial aircraft for each 10 year scheduled maintenance strip down. In aircrafts, corrosion is caused by the electrical interaction between metal and the atmosphere. What is left from this process of corrosion is metal in the form of rust or the dusty material that can be rubbed off an aluminium window frame. The Scanning Kelvin Probe can capture a picture of the electrochemical reactions within minutes compared to other instruments which take longer to collect data, and then only from a small section of material.

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 also be simulated and studied using the Scanning Kelvin Probe with speed and accuracy.

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 results of the study have brought an understanding of how fast corrosion initiation proceeds and the chemical changes occurring on the surface of the zinc metal.