Growth of Small Alumina Clusters during Ladle Deoxidation

For the first time, the size distribution of small clusters was determined in a systematic manner from samples taken during deoxidation with aluminium in an induction-stirred ladle. Chemical and microscopic analyses of samples were performed. The results indicated rapid cluster growth throughout the experiment and at the end of the experiment a majority of the small inclusions were found to be bound in clusters. The cluster growth was concluded to be by collision. Growth-model calculations were carried out to verify the experimental findings. In order to perform these calculations, a method first needed to be developed for conversion of the experimental data determined per unit area to data given per unit volume. Next, the cluster collision diameter was modelled using a theory for fractal aggregates. The results from the growth-model calculations, simulating deoxidation with aluminium, were found to agree well with the experimental results.