March 21, 2022

Stirring the pot for increased material resilience in coating baths

Another exciting project is underway within the Steel Research Hub, which brings together expertise from the University of Wollongong (UOW) and BlueScope (BSL) to focus on the surface engineering of materials for increased resilience in aluminium-zinc (Al-Zn) metal coating baths.

Components used in the molten metal bath in hot dip Al-Zn and Zn coating processes are exposed to extremely harsh operating conditions. The aggressive nature of the reaction between immersed equipment and the liquid metal means that materials must be carefully selected, and generally have limited-service life. Austenitic stainless steels are something of an industry standard for immersed pot equipment due to their high temperature corrosion resistance and good mechanical properties at high temperatures in metal coating environments.

After prolonged use, immersed pot equipment suffers from excessive corrosion damage and breakaway intermetallic alloy spike growth often referred to as “horn growth” imperfections. To combat the degradation mechanisms and improve the service life of immersed pot equipment, a concerted research effort is required in these broad categories:

1. the selection of materials that are compatible with the molten coating alloy bath
2. surface modification of components by the application of highly resistant coatings and
3. the application of coatings to inhibit the nucleation and growth of dross intermetallic particles, and to minimise build-up of dross particles on immersed pot equipment.

The findings of this research will lead to improved understanding of the fundamental reactions between materials and molten coating metal, the development of coating materials for immersed pot hardware, techniques and expertise in Zn-Al bath management practices that extend functional pot life of components.

The project team consists of UOW’s Chief Investigator Associate Professor Yue Zhao and a PhD candidate (to be employed), and Associate Researchers from Industry, Dr Joe Williams and Dr Nega Setargew.

The Steel Research Hub and University of Wollongong would like to wish this project team the very best in their research and we are sure there will be many highlights to come from this project.