Processing Sodium Tellurite Melts in Low Gravity Drop Shaft. Part I. Melt Evaporation and Formation of Solid Particles from Vapor


Glasses of Na2O · 8TeO2 and Na2O · 4TeO2 compositions adhered to a small platinum heating coil (2 to 3 mm ID, 5 to 6 mm long) were melted and evaporated in low gravity using the drop shaft at the Japan Microgravity Center (JAMIC). The gravity level attained during the 10 s free fall was in the order of 10-3 g. The species evaporated from the melt in low gravity generally formed a spherical smoke cloud surrounding the melt, whose size depended on the melt temperature and also on the time the melt evaporated in low gravity. The shape of the cloud was found to depend on several other factors, namely, the uniformity of heating, amount of melt, and the presence of gas bubbles in the melt. The evaporating species formed nearly perfect spheres of pure TeO2 whose diameter ranged from 0.05 to 20 μm. The size of TeO2 microspheres increased with increasing melt temperature and time in low gravity, and was 5 to 10 times larger than that of similar particles prepared at 1-g.


Materials Science and Engineering

Keywords and Phrases

Bubbles (in fluids); Evaporation; Glass; Gravitational effects; Melting; Particles (particulate matter); Platinum; Tellurium compounds; Temperature; Vapors; Low gravity drop shaft; Melt temperature; Platinum heating coil; Sodium tellurite melts; Spherical smoke cloud

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Article - Journal

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© 2002 Springer Netherlands, All rights reserved.

Publication Date

01 Sep 2002