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

Related Subjects

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