|About this Abstract
||Materials Science & Technology 2019
||Powder Metallurgy of Light, Reactive and Other Non-ferrous Metals
||Gas Atomization Processing of Calcium Powder with In situ Passivation
||Iver E. Anderson, Charles Czahor, Dustin Hickman, Trevor Riedemann
|On-Site Speaker (Planned)
||Iver E. Anderson
The availability of fine Ca metal powder is a principal barrier to the development of Al/Ca composite conductors by blending with fine Al powder, compaction, co-extrusion, and wire drawing. Unfortunately, calcium does not form a protective native oxide coating, permitting reaction with ambient humidity. Based on the previous example of magnesium passivation with sulfur hexafluoride (SF6), preliminary experiments indicated that the use of SF6 gas with Ca resulted in an undesirable layer of sulfur on the metal surface. An alternative volatile fluid called Novec™ 612 (with low global warming potential) was tested on melted/solidified Ca and resulted in a thin, F-containing layer. Calcium was gas-atomized with Ar+Novec™ mixed gas injected downstream into the spray chamber through a gas halo after droplet solidification has occurred. The powder was analyzed for topography, surface chemistry, and oxidation rate behavior to indicate successful passivation. Work funded by USDOE-OE through Ames Lab contract DE-AC02-07CH11358.