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Sodium sulfate-induced corrosion of pure nickel and superalloy Udimet 700 in a high velocity burner rig at 900 CSodium sulfate-induced corrosion of pure nickel and a commercial nickel-base superalloy, Udimet 700 (U-700), were studied at 900 C in a Mach 0.3 burner rig with different Na levels in the combustor. The corrosion rate of Ni was independent of the Na level in the combustor and considerably lower than that measured in laboratory salt spray tests. The lower rates are associated with the deposition of only a small amount of Na2SO4 on the surface of the NiO scale. Corrosion of U-700 was observed to occur in two stages. During the first stage, the corrosion proceeds by reaction of Cr2O3 scale with the Na2SO4 and evaporation of the Na2CrO4 reaction product from the surface of the corroding sample. Cr depletion in the alloy occurs and small sulfide particles are formed in the Cr depletion zone. Extensive sulfidation occurs during the second state of corrosion, and a thick scale forms. The relationship between the corrosion rate of U-700 and the Na level in the combustor gives a good correlation in the range of 0.3 to 1.5 ppm by weight Na. Very low levels of Na in the combustor cause accelerated oxidation of U-700 without producing the typical hot corrosion morphology.
Document ID
19880033039
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Misra, A. K.
(NASA Lewis Research Center; Case Western Reserve University Cleveland, OH, United States)
Date Acquired
August 13, 2013
Publication Date
July 1, 1987
Publication Information
Publication: Corrosion
Volume: 43
ISSN: 0010-9312
Subject Category
Metallic Materials
Accession Number
88A20266
Distribution Limits
Public
Copyright
Other

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