Chromium and reactive element modified aluminide diffusion coatings on superalloys: Environmental testing

Journal Article · Thu Apr 01 00:00:00 EST 1993 · Journal of the Electrochemical Society; (United States)

DOI:https://doi.org/10.1149/1.2056220· OSTI ID:6397994

Bianco, R; Rapp, R A ^[1]; Smialek, J L ^[2]

---

1. Ohio State Univ., Columbus (United States)
2. Lewis Research Center, Cleveland, OH (United States)

The isothermal oxidation of reactive element (RE)-doped aluminide coatings on IN 713LC alloy substrates at 1100 C in air formed a continuous slow-growing [alpha]-Al[sub 2]O[sub 3] scale after 44 h of exposure. RE-free (reactive element-free) aluminide coatings were characterized by a cracked oxide scale which exposed an underlying voided coating surface. The cyclic oxidation behavior of Cr/RE-modified aluminide diffusion coatings on Rene 80 and IN 713LC alloy substrates, and of RE-doped aluminide coatings on IN 713LC alloy substrates, at 1100 C in static air was determined. Coatings deposited by the above pack (AP) arrangement, as opposed to the powder contacting (PC) arrangement, showed improved resistance to cyclic oxidation attack. RE-doped and Cr/RE-modified aluminide coatings exhibited considerably more adherent protective Al[sub 2]O[sub 3] scales compared to undoped aluminide coatings. The hot corrosion behavior of Cr/RE-modified aluminide coatings on Rene 80 and Mar-M247 alloy substrates at 900 C in a 0.1 % sO[sub 2]/O[sub 2] gas mixture also was determined. The Cr/RE-modified aluminide coatings provided better resistance to hot corrosion attack (i.e., thin film studies) than a commercial low activity aluminide coating. Coating lifetimes were strongly dependent on the chromium surface composition, since a mixed (Al, Cr)[sub 2]O[sub 3] scale better resists attack by the molten salt.

• OSTI ID: 6397994
• Journal Information: Journal of the Electrochemical Society; (United States), Vol. 140:4; ISSN 0013-4651
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ALUMINIUM COMPOUNDS
CORROSION RESISTANCE
CHROMIUM COMPOUNDS
DIFFUSION COATINGS
INCONEL 713LC
MARAGING STEELS
RENE 80
ALUMINIUM OXIDES
CHEMICAL COMPOSITION
CHROMIUM OXIDES
CORROSIVE EFFECTS
HEAT RESISTING ALLOYS
INTERMETALLIC COMPOUNDS
OXIDATION
SULFUR DIOXIDE
TEMPERATURE RANGE 1000-4000 K
ALLOY-NI60CR14CO10TI5MO4W4AL3
ALLOY-NI75CR12AL6MO5
ALLOYS
ALUMINIUM ALLOYS
BORON ADDITIONS
BORON ALLOYS
CHALCOGENIDES
CHEMICAL REACTIONS
CHROMIUM ALLOYS
COATINGS
COBALT ALLOYS
CORROSION RESISTANT ALLOYS
HEAT RESISTANT MATERIALS
INCONEL ALLOYS
IRON ALLOYS
IRON BASE ALLOYS
MARTENSITIC STEELS
MATERIALS
MOLYBDENUM ALLOYS
NICKEL ALLOYS
NICKEL BASE ALLOYS
NIOBIUM ALLOYS
OXIDES
OXYGEN COMPOUNDS
STEELS
SULFUR COMPOUNDS
SULFUR OXIDES
T
TEMPERATURE RANGE
TITANIUM
TRANSITION ELEMENT COMPOUNDS
360601* - Other Materials- Preparation & Manufacture
360604 - Materials- Corrosion
Erosion
& Degradation