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Coatings for directional eutecticsCoatings developed to provide oxidation protection for the directionally-solidified eutectic alloy NiTaC-B (4.4 weight percent Cr) were evaluated. Of seven Co-, Fe- and Ni-base coatings that were initially investigated, best resistance to cyclic oxidation was demonstrated by duplex coatings fabricated by depositing a layer of NiCrAl(Y) by vacuum evaporation from an electron beam source followed by deposition of an Al overlayer using the pack cementation process. It was found that addition of carbon to the coating alloy substantially eliminated the problem of fiber denudation in TaC-type eutectic alloys. Burner rig cycled NiTaC-B samples coated with Ni-20Cr-5Al-0.1C-0.1Y+Al and rupture-tested at 1100 deg C performed as well as or better than uncoated, vacuum cycled and air-tested NiTaC-13; however, a slight degradation with respect to uncoated material was noted in air-stress rupture tests at 870 deg C for both cycled and uncycled samples.
Document ID
19770055122
Acquisition Source
Legacy CDMS
Document Type
Conference Paper
Authors
Rairden, J. R.
(General Electric Co. Schenectady, NY, United States)
Jackson, M. R.
(GE Metallurgy Laboratory Schenectady, N.Y., United States)
Date Acquired
August 9, 2013
Publication Date
September 1, 1976
Subject Category
Metallic Materials
Report/Patent Number
GE-R76CRD257
Accession Number
77A37974
Funding Number(s)
CONTRACT_GRANT: NAS3-16793
CONTRACT_GRANT: NAS3-17815
Distribution Limits
Public
Copyright
Other

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