Metallurgical Chemistry of Liquid Alloys and Molten Slags

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The following research activities have been designed with three objectives in mind: 1) Development of new fundamental knowledge that relates to the processing of liquid metal alloys and oxide melts; 2) Thematic topics that will fulfill the requirements for graduate and undergraduate thesis projects; and 3) Research that will provide students with hands-on training experience in experimental techniques and materials characterization procedures involving high temperature furnaces, advanced electron-optic facilities, XRD equipment and modern analytical systems. To achieve these objectives, research will be conducted based on two distinct themes: nitrogen dissolution in molten oxides, and solute interactions within iron alloys. ******1. The processes involved in iron and steelmaking are based directly or indirectly on the control of slag chemistry, which in turn has a profound influence on slag structure, and therefore slag properties and performance. In view of the importance of slag control there is an increasing need to generate information pertaining to the characterization, properties and performance of oxide melts and synthetic fluxes. The increasing demand for low nitrogen steel has prompted interest in the possibility of using custom-designed fluxes to remove nitrogen from steel melts. Nitrogen can dissolve in slags in two distinct forms, free nitride where the nitrogen replaces free oxygen ions; and incorporated nitride where the nitrogen replaces oxygen ions involved in the network of polymerized anions. The objective of the proposed research will be to conduct thermodynamic and kinetic studies using a thermo-gravimetric technique and a selective analytical method to quantify the different species of nitrides present in different oxide melts and synthetic fluxes and thus develop an improved understanding of how slag chemistry influences slag performance.******2. In recent years the need for alloy irons for critical applications within the automotive sector have required the production of materials with very low contents of non-metallic inclusions and carefully controlled amounts of the residual elements oxygen, sulphur and nitrogen. The nodularization and high temperature properties of these ductile irons are strongly influenced by silicon, aluminum, cerium and other rare earths. The objective of this project is to use levitated droplets to determine the effect of these alloying additives on the activity coefficients of oxygen, sulphur and nitrogen with iron-carbon alloys, rather than pure iron, as the solvent. Falling droplet experiments will also be conducted in order to determine the reoxidation behaviour and nitrogen absorption encountered when these alloy irons are allowed to fall for fractions of a second through air and potentially protective atmospheres such as argon and nitrogen.  **************************