The corrosion of Ni[sub 3]Al in a combustion gas with and without Na[sub 2]SO[sub 4]-NaCl deposits at 600-800[degrees]C

Journal Article · Sat Oct 01 00:00:00 EDT 1994 · Oxidation of Metals; (United States)

DOI:https://doi.org/10.1007/BF01052027· OSTI ID:6740189

Niu, Y ^[1]; Gesmundo, F; Viani, F ^[2]; Wu, W ^[3]

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1. Institute of Corrosion and Protection of Metals, Shenyang (China) Istituto di Chimica, Genova (Italy)
2. Institute of Corrosion and Protection of Metals, Shenyang (China)
3. Istituto di Chimica, Genova (Italy)

The corrosion behavior of Ni[sub 3]Al containing small additions of Ti, Zr, and B in combustion gases both with and without Na[sub 2]SO[sub 4]-NaCl deposits at 600-800[degrees]C has been studied for times up to four days. The corrosion of the salt-free Ni[sub 3]Al leads to the formation of very thin alumina scales at 600[degrees]C but of mixed NiO-Al[sub 2]O[sub 3] scales containing also some sulfur compounds at higher temperatures, while the rate increases with temperature up to 800[degrees]C. The presence of the salt deposits considerably accelerates the corrosion rate, especially at 600 and 800[degrees]C. The duplex scales formed at 600[degrees]C are composed mostly of a mixture of NiO and unreacted salt in the outer layer and of alumina and aluminum sulfide with some nickel compounds in the inner layer. The scales grown at 700[degrees]C contain only one layer of complex composition, while those grown at 800[degrees]C are similar but have an additional outer layer containing similar amounts of nickel and aluminum. At 600 and 700[degrees]C NiSO[sub 4] can be detected also in the salt layer. The samples corroded at 700[degrees]C and 800[degrees]C also show an Al-depleted zone containing titanium sulfide precipitates at the surface of the alloy. The hot corrosion of Ni[sub 3]Al involves a combination of various mechanisms, including fluxing of the oxide scale as well as mixed oxidation-sulfidation attack. At all temperatures Ni[sub 3]Al shows poor resistance to hot-corrosion attack as a result of the formation of large amounts of Ni compounds in the scales.

• OSTI ID: 6740189
• Journal Information: Oxidation of Metals; (United States), Vol. 42:3-4; ISSN 0030-770X
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
20 FOSSIL-FUELED POWER PLANTS
ALUMINIUM ALLOYS
CORROSION
INTERMETALLIC COMPOUNDS
NICKEL BASE ALLOYS
FLUE GAS
SCALING
SODIUM CHLORIDES
SODIUM SULFATES
TEMPERATURE RANGE 1000-4000 K
ALKALI METAL COMPOUNDS
ALLOYS
CHEMICAL REACTIONS
CHLORIDES
CHLORINE COMPOUNDS
GASEOUS WASTES
HALIDES
HALOGEN COMPOUNDS
NICKEL ALLOYS
OXYGEN COMPOUNDS
SODIUM COMPOUNDS
SULFATES
SULFUR COMPOUNDS
TEMPERATURE RANGE
WASTES
360105* - Metals & Alloys- Corrosion & Erosion
200104 - Fossil-Fueled Power Plants- Components