Pitting and crevice corrosion of iron aluminides in a mild acid-chloride solution

Journal Article · Thu Sep 01 00:00:00 EDT 1994 · Corrosion (Houston); (United States)

DOI:https://doi.org/10.5006/1.3293541· OSTI ID:6955835

Kim, J G; Buchanan, R A ^[1]

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1. Univ. of Tennessee, Knoxville, TN (United States). Dept. of Materials Science and Engineering

Aqueous corrosion (pitting and crevice) characteristics of iron aluminides in a mild acid-chloride (Cl[sup [minus]]) solution (200 ppm Cl[sup [minus]] [5.5 [times] 10[sup [minus]3] M sodium chloride [NaCl]] at pH 4 [6.25 [times] 10[sup [minus]5] M sulfuric acid H[sub 2]SO[sub 4]]) were studied as functions of alloying additions and thermomechanical processing methods. Electrochemical results indicated beneficial effects of chromium (Cr) and molybdenum (Mo). Immersion tests confirmed the electrochemical results and revealed the time dependence of localized corrosion behavior. The crevice corrosion behavior of iron aluminides was investigated using electrochemical and immersion crevice tests. The difference between crevice and pitting susceptibilities was minimal for the Mo-containing iron aluminide but significant for the iron aluminides without Mo. X-ray photoelectron spectroscopy (XPS) of surfaces passivated in the mild acid-chloride solution revealed the passive films of iron aluminides were composed mainly of oxidized aluminum (Al[sub 2]O[sub 3]) that coexisted with chromium oxide (Cr[sub 2]O[sub 3]) and molybdenum oxide (MoO[sub 3]). XPS results also indicated the role of Mo in improving the localized corrosion resistance of the Cr-containing iron aluminides. Mo facilitated the formation of a high Al content in the passive film and impeded the adsorption of Cl[sup [minus]] on the surface.

• OSTI ID: 6955835
• Journal Information: Corrosion (Houston); (United States), Vol. 50:9; ISSN 0010-9312
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ALUMINIUM ALLOYS
CREVICE CORROSION
PITTING CORROSION
CHROMIUM
METALLURGICAL EFFECTS
IRON ALLOYS
MOLYBDENUM
SODIUM CHLORIDES
CORROSIVE EFFECTS
SULFURIC ACID
ALUMINIUM OXIDES
CHROMIUM OXIDES
MOLYBDENUM OXIDES
PASSIVATION
PROTECTIVE COATINGS
ALKALI METAL COMPOUNDS
ALLOYS
ALUMINIUM COMPOUNDS
CHALCOGENIDES
CHEMICAL REACTIONS
CHLORIDES
CHLORINE COMPOUNDS
CHROMIUM COMPOUNDS
COATINGS
CORROSION
ELEMENTS
HALIDES
HALOGEN COMPOUNDS
HYDROGEN COMPOUNDS
INORGANIC ACIDS
METALS
MOLYBDENUM COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
REFRACTORY METAL COMPOUNDS
SODIUM COMPOUNDS
TRANSITION ELEMENT COMPOUNDS
TRANSITION ELEMENTS
360105* - Metals & Alloys- Corrosion & Erosion