Paper Title:
Effective Protection of Magnesium Melt Surface from Oxidation Using HFC125-Containing Shielding Gas
  Abstract

In accordance with the ignition-prevention mechanism of F-containing shielding gas, HFC125 (pentafluoroethane) possesses the potential for forming a F-containing dense film on the surface of a Mg melt to protect it from oxidation and ignition. Importantly, HFC125 has a GWP (global warming potential) value around one eighth that of SF6, and is one-third the price (in China). The effect of HFC125, diluted in a nitrogen based shielding gas was examined via systematic experiments under variable temperature, concentration, and flux. The results showed that a shiny metallic film instantly formed on the surface of an Mg melt similar to what was observed with SF6. The protective effect varied with temperature, concentration and flux. The chemistry and structure of the protective film was characterized by SEM, EDS and XRD, and showed that the film was a dense, continuous layer of Mg oxide and fluoride. The results obtained lead to a conclusion that HFC125 is capable of providing effective protection and is, therefore, an ideal alternative to SF6 in terms of protective effectiveness, reduced GWP and cost.

  Info
Periodical
Materials Science Forum (Volumes 546-549)
Edited by
Yafang Han et al.
Pages
119-122
DOI
10.4028/www.scientific.net/MSF.546-549.119
Citation
G. Q. You, S. Y. Long, R. F. Li, "Effective Protection of Magnesium Melt Surface from Oxidation Using HFC125-Containing Shielding Gas", Materials Science Forum, Vols. 546-549, pp. 119-122, 2007
Online since
May 2007
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Price
$32.00
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