THe hot-corrosion behavior of novel Co-deposited chromium-modified aluminide coatings

Journal Article · Tue Dec 01 00:00:00 EST 1992 · Oxidation of Metals; (United States)

DOI:https://doi.org/10.1007/BF00665662· OSTI ID:6950782

Gleeson, B; Cheung, W H; Costa, W Da; Young, D J ^[1]

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1. Univ. of New South Wales, Kensington (Australia)

This paper reports the successful co-deposition of inclusion-free chromium-modified aluminide coatings using a pack-cementation process. The substrate used was the nickel-base superalloy, Rene 80H. The coatings were of the outward-diffusion type; however, unlike the usual outward-diffusion coatings, the present coatings were relatively free of pack inclusions. The coatings consisted of [alpha]-Cr precipitates in a matrix of [beta]-NiAl. The morphology and distribution of the [alpha]-Cr precipitates could be adjusted to the extent that two types of coating structures could be obtained. The Type 1 coating structure contained lamellar [alpha]-Cr precipitates situated in the surface region of the coating, whereas the Type 2 coating structure contained small, spheroidal [alpha]-Cr precipitates distributed throughout the outer of a two-layered coating. Both coating types exhibited significantly improved hot-corrosion resistance in a 0.1% SO[sub 2]-O[sub 2] environment at 900[degrees]C compared to a commercial aluminide coating. A study of the corrosion behavior of Type 1 coatings containing pack inclusions showed that the inclusions were deleterious to the corrosion resistance of the coatings. The corrosion behavior of chromium-aluminide coatings was dependent on both the distribution and amount of [alpha]-Cr precipitates in the coating.

• OSTI ID: 6950782
• Journal Information: Oxidation of Metals; (United States), Vol. 38:5-6; ISSN 0030-770X
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
CHROMIUM ALLOYS
CORROSION
COBALT ALLOYS
NICKEL BASE ALLOYS
PROTECTIVE COATINGS
DEPOSITION
ALUMINIUM ALLOYS
ALUMINIUM OXIDES
CHROMIUM
CORROSION RESISTANCE
INCLUSIONS
MOLYBDENUM ALLOYS
MORPHOLOGY
TEMPERATURE RANGE 0400-1000 K
TITANIUM ALLOYS
TUNGSTEN ALLOYS
TURBINE BLADES
ALLOYS
ALUMINIUM COMPOUNDS
CHALCOGENIDES
CHEMICAL REACTIONS
COATINGS
ELEMENTS
METALS
NICKEL ALLOYS
OXIDES
OXYGEN COMPOUNDS
TEMPERATURE RANGE
TRANSITION ELEMENTS
360105* - Metals & Alloys- Corrosion & Erosion