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Reactions occurring during the sulfation of sodium chloride deposited on alumina substratesThe reaction between solid NaCl and air containing 1 pct SO2 has been studied between 500 and 700 C. The reaction product, Na2SO4, forms not only on the surface of the NaCl but also on surrounding areas of the substrate due to the volatility of the NaCl at these temperatures. At the higher temperatures, the vapor pressure of NaCl is so high that the majority of the reaction product is distributed on the substrate. Above 625 C, the reaction product is a liquid solution of NaCl and Na2SO4 that exists only so long as NaCl is supplied from the original crystal source. Eventually, the liquid solidifies by constitutional solidification as the NaCl is converted to Na2SO4. While it exists, the liquid NaCl-Na2SO4 solution is shown to be highly corrosive to Al2O3 and, on a scale of Al2O3 growing on alloy HOS 875, particularly attacks the grain boundaries of the scale at preferred sites where chromium and iron oxides and sulfides rapidly develop. This is proposed as one mechanism by which NaCl deposition contributes to the initiation of low temperature hot corrosion.
Document ID
19870032949
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Wu, C. S.
(China Steel Corp. Republic of China, United States)
Birks, N.
(Pittsburgh, University PA, United States)
Date Acquired
August 13, 2013
Publication Date
October 1, 1986
Publication Information
Publication: Electrochemical Society, Journal
Volume: 133
ISSN: 0013-4651
Subject Category
Inorganic And Physical Chemistry
Accession Number
87A20223
Funding Number(s)
CONTRACT_GRANT: NAG3-44
Distribution Limits
Public
Copyright
Other

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