In-Situ Gas-Phase Passivation of Molten Calcium Surfaces to Enable Development of Atomization Method for Generating Calcium Powder

摘要

Deformation processed aluminum/calcium composites are lighter, stronger, and more conductive than conventional overhead power transmission conductors, which gives them the potential to reduce electrical losses, lower costs, and enhance grid reliability. A principal barrier to full strengthening of Al/Ca composites is availability of fine Ca metal powder for co-extrusion with commercial Al powder. Calcium powder does not form a protective oxide layer on its surface and must be passivated to ensure safe production and handling. Experiments using an Induction Melting Passivation (IMPass) apparatus developed earlier and used to successfully passivate Mg powder were used to identify appropriate gas mixture and processing conditions for Ca metal. Auger electron spectroscopy (AES), depth profiling, and scanning electron microscopy (SEM) were used to evaluate the passivation characteristics. These findings will allow for lab-scale atomization trials and eventual scale-up allowing safe commercial production of Ca powder.