South Wales Materials Association lecture

Dr James Sullivan - Swansea University

Zn-Mg-Al alloys (ZMA) are becoming an increasingly popular choice for galvanised coatings on steel due to their apparent performance and cost benefits over traditional hot dipped zinc coatings.  A novel flow cell has been developed that allows the observation of corrosion mechanisms at a microstructural level in a new alloy developed by Tata Steel Europe, immersed in 0.1% NaCl, using time lapse microscopy. The cell has been developed to allow flexibility of experimental design in that the corrosion mechanism may be observed at a microstructural level with time enabling preferential phase attack to be determined. The technique has proved to be extremely versatile and has allowed not only the mechanisms of corrosion in the alloy to be determined but also the deposition of corrosion products and the formation of pH gradients to be imaged. This novel technique provides new insight into the initiation sites of corrosion in alloys and thus provides potential to alter the microstructure using on line processing conditions to effect changes in the corrosion behaviour. The experiment also provides scope for the investigation of the effects of inhibitor additions into the system once corrosion has been initiated, ionic changes and pH on the corrosion mechanisms of such materials.  

time tbc