Reaction of SiF4 with Al Metal

Reaction of SiF4 with Al Metal

The reaction of SiF 4 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 apprecia...

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Bibliographic Details
Published in:Metallurgical and materials transactions. E, Materials for energy systems Vol. 4; no. 1; pp. 29 - 40
Main Authors: Xie, Xiaobing, Lau, Kai, Sanjurjo, Angel, Alkhudhiri, Abdullah I., Alzaben, Abdullah, Alabbad, Waiel
Format: Journal Article
Language:English
Published: New York Springer US 01-03-2017
Springer Nature B.V
Subjects:
Aluminum base alloys
Aluminum fluorides
Characterization and Evaluation of Materials
Chemistry and Materials Science
Convection currents
Energy
Exothermic reactions
Materials Science
Metallic Materials
Nanotechnology
Reaction products
Room temperature
Silicon
Structural Materials
Surfaces and Interfaces
Thin Films
Whiskers (metals)
Reaction Zone
Chemical Vapor Transport
Aluminothermic Reduction
Graphite Crucible
Cool Wall
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Summary:The reaction of SiF 4 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 AlF 3 . 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, NaAlF 4 , AlF 3 , 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 SiF 2 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 AlF 3 and SiF 4 gas, respectively.
ISSN:2196-2936
2196-2944
DOI:10.1007/s40553-016-0104-y