Abstract
The reaction of SiF4 gas with aluminum (Al) was studied at temperatures ranging from room temperature to 1723 K (1450 °C). Although thermochemical estimates indicate that reactions throughout the temperature range should be thermodynamically favorable, we found that no reaction takes place appreciably until Al is heated to around 1473 K (1200 °C). The reaction products consist of fine powders of Si, Al, and AlF3. Some of the reaction products were transported away from the reaction zone by strong convection currents resulting from the exothermic reaction. Even at approximately 1673 K (1400 °C), the reaction rate is slow and a significant amount of Al remains unreacted. When NaF powders were used to line the graphite reactor, NaAlF4, AlF3, and Si powders were observed on the upper cooler walls of the reactor, and Si whiskers were formed just above the Al-Si alloy globule on the bottom of the crucible. We found evidence of the formation of AlF and SiF2 vapor species in the reaction zone, which then disproportionated along the cooler walls of the reactor, generating powders of Al and Si and regenerating condensable AlF3 and SiF4 gas, respectively.
Similar content being viewed by others
References
M.A. Hunter, J. Am. Chem. Soc. 32, 330–36 (1910)
A. W. J. Kroll: US Patent 2,205,854, 1940
W.J. Kroll, Trans. Electrochem. Soc. 112, 35–47 (1940)
K. I. Joseph: US Patent 2,909,411 A, 1957
J. M. Blocher Jr., M. F. Browning, W. J. Wilson, and D. C. Carmichael: 2nd Quarterly Progress Report for JPL under JPL Contract 954339, 1976
J. H. Francis, D. F. Ciliberti, T. N. Meyer, and M. G. Fey: US Patent 4,239,740 A, 1979
P. Woditsch, M. Abels, and B. Brazel: US Patents 4,525,334, 1985
I. Barin, G. Platzki, Thermochemical Data of Pure Substances, 3rd Edition, Two volumes (VCH Publishers, New York, 1995)
S. Sakaguchi: PCT International Patent WO2007/119605, 2007
P. Woditsch, W. Koch, Sol. Energy Mater. Sol. Cells 72, 11–26 (2002)
K. Yasuda, K. Saegusa, T.H. Okabe, Mater. Trans. 50, 2873–78 (2009)
A. Sanjurjo, K. M. Sancier, R. M. Emerson, and S. C. Leach: Proceedings of the Flat-Plate Solar Array Project Workshop on Low-Cost Polysilicon for Terrestrial Photovoltaic Solar-Cell Applications, 1986, vol. 1, pp. 325–43
A. Sanjurjo, L. Nanis, K. Sancier, R. Bartlett, V. Kapur, J. Electrochem. Soc. 128, 179–84 (1981)
X. Xie, J. Bao, A. Sanjurjo, Mater. Trans. E 3E, 299–312 (2016)
K. Yasuda, T.H. Okabe, JOM 62(12), 94–101 (2010)
E. Wiberg, N. Wilberg, Inorganic Chemistry (Academic Press, Berlin, 2001), p. 823
C.M.Y. Berta, Z.L. Wang, Solid State Commun. 129, 681–85 (2004)
J.L. Murray, A.J. McAlister, Bull. Alloy Phase Diagr. 5, 74–84 (1984)
W. C. Reynolds: Interactive Computer Programs for Chemical Equilibrium Analysis, Free Software from Stanford University, Stanford, 1981
Acknowledgment
The authors would like to express appreciation to King Abdulaziz City for Science and Technology (KACST) as well as SRI International for providing the funds and support for this work.
Author information
Authors and Affiliations
Corresponding author
Additional information
Manuscript submitted June 29, 2016.
Rights and permissions
About this article
Cite this article
Xie, X., Lau, K., Sanjurjo, A. et al. Reaction of SiF4 with Al Metal. Metallurgical and Materials Transactions E 4, 29–40 (2017). https://doi.org/10.1007/s40553-016-0104-y
Received:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s40553-016-0104-y