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Oxidation of low cobalt alloysFour high temperature alloys: U-700, Mar M-247, Waspaloy and PM/HIP U-700 were modified with various cobalt levels ranging from 0 percent to their nominal commercial levels. The alloys were then tested in cyclic oxidation in static air at temperatures ranging from 1000 to 1150 C at times from 500 to 100 1 hour cycles. Specific weight change with time and X-ray diffraction analyses of the oxidized samples were used to evaluate the alloys. The alloys tend to be either Al2O3/aluminate spinel or Cr2O3/chromite spinel formers depending on the Cr/Al ratio in the alloy. Waspaloy with a ratio of 15:1 is a strong Cr2O3 former while this U-700 with a ratio of 3.33:1 tends to form mostly Cr2O3 while Mar M-247 with a ratio of 1.53:1 is a strong Al2O3 former. The best cyclic oxidation resistance is associated with the Al2O3 formers. The cobalt levels appear to have little effect on the oxidation resistance of the Al2O3/aluminate spinel formers while any tendency to form Cr2O3 is accelerated with increased cobalt levels and leads to increased oxidation attack.
Document ID
19830003021
Acquisition Source
Legacy CDMS
Document Type
Conference Paper
Authors
Barrett, C. A.
(NASA Lewis Research Center Cleveland, OH, United States)
Date Acquired
August 11, 2013
Publication Date
October 1, 1982
Publication Information
Publication: COSAM (Conserv. Of Strategic Aerospace Mater.) Program Overview
Subject Category
Metallic Materials
Accession Number
83N11291
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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