Thomas Jurak, a Steel Research Hub PhD candidate at the University of Wollongong explored alternative surface treatment approaches to increase corrosion protection of metallic coated products.

 

The challenge

Metal coated steel products are passivated to protect against wet stack corrosion. Wet stack corrosion can occur when metallic alloy coated products are exposed to wet storage conditions, resulting in the formation of undesirable corrosion products on affected surfaces. Such coatings are vulnerable to wet stack corrosion when metal coated product is stored as a coil between manufacture and downstream processing, or after post‐processing of the product into tightly nesting profiles.

His team’s research has, in part, explored alternative surface treatments to provide increased protection to coated steel products in the downstream supply chain, as well as uniform weathering of metallic surface finishes post-installation.

 

The response

The Steel Research Hub in collaboration with BlueScope, have developed a novel electrochemical cell setup that utilises the Single Substrate (SS) Electrochemical Noise Measurement (ENM) technique to acquire quantitative electrochemical data of wet stack corrosion. There are significant advantages to using an electrochemical test; first, significantly faster testing times (hours rather than weeks) and second, quantitative electrochemical data which can be used to study corrosion mechanisms and rates. Understanding the mechanism of wet stack corrosion is also critical in the development of a suitable protective system, and a robust physical model requires accurate quantitative data. Unlike other electrochemical testing methods, this is achieved without the need for polarization of the sample, making the test non-destructive and permitting continuous monitoring over time.

 

The impact

The research team aimed to develop a more in-depth understanding of wet stack corrosion to assist in developing alternative corrosion inhibitors for zinc and 55% Al‐Zn alloy coatings in the future. Experiments utilising the novel ENM setup have provided some insight into how wet stack corrosion progresses, as well as assessing the effectiveness of rare earth elements as an alternative to traditional treatments. Furthermore, the team have developed a theoretical model validating SS ENM.  This has important consequences for the future of ENM and its use in measuring real world corrosion events in-situ. An exciting avenue for further research is the application of this in-situ ENM technique to corrosion sensors in atmospheric environments, both to facilitate characterisation of a corrosive environment and detailed assessment of new products and surface treatments in real-world environments.

 

Personal highlights

Thomas said it has been a great pleasure having worked with his research team over the past four years. “They have always been highly supportive of my ideas, my future career, and the project in general. I am very much looking forward to working with them in the future.”

Another highlight was the privilege of travelling to Beijing in December 2016 for the Beihang University-University of Wollongong Bilateral Materials Workshop. It was his first overseas academic event and first visit to an overseas university.