Pitting corrosion of titanium

Journal Article · Tue Mar 01 00:00:00 EST 1994 · Journal of the Electrochemical Society; (United States)

DOI:https://doi.org/10.1149/1.2054783· OSTI ID:7198752

Casillas, N; Charlebois, S; Smyrl, W H ^[1]; White, H S ^[2]

---

1. Univ. of Minnesota, Minneapolis, MN (United States). Dept. of Chemical Engineering
2. Univ. of Utah, Salt Lake City, UT (United States). Dept. of Chemistry

The breakdown of native and anodically grown oxide films on Ti electrodes is investigated by scanning electrochemical microscopy (SECM), video microscopy, transmission electron microscopy, and voltammetry. SECM is used to demonstrated that the oxidation of Br[sup [minus]] on Ti occurs at microscopic surface sites (10 to 50 [mu]m diam, 30 sites/cm[sup 2]) that are randomly positioned across the oxide surface. After determining the position of the active sites for Br[sup [minus]] oxidation, breakdown of the oxide is initiated by increasing the electrode potential to more positive values. Direct correspondence is observed between the location of the electroactive sites and corrosion pits, indicating that oxide breakdown is associated with a localized test of high electrical conductivity. The potential at which pitting is observed in voltammetric experiments is found to be proportional to the average oxide thickness, for values ranging between 20 and 100 [angstrom], indicating that breakdown is determined either by the magnitude of the electric field within the oxide or by the interfacial potential at the oxide/Br[sup [minus]] solution interface. Pitting occurs at significantly lower potentials in Br[sup [minus]] solutions than in Cl[sup [minus]] solutions, suggesting a strong chemical interaction between the TiO[sub 2] surface and Br[sup [minus]]. A mechanism of oxide breakdown is proposed that is based on the potential-dependent chemical dissolution of the oxide at microscopic surface sites.

• OSTI ID: 7198752
• Journal Information: Journal of the Electrochemical Society; (United States), Vol. 141:3; ISSN 0013-4651
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
TITANIUM
PITTING CORROSION
AQUEOUS SOLUTIONS
BROMIDES
CHEMICAL REACTION KINETICS
CHLORIDES
DECOMPOSITION
PROTECTIVE COATINGS
STABILITY
TITANIUM OXIDES
BROMINE COMPOUNDS
CHALCOGENIDES
CHEMICAL REACTIONS
CHLORINE COMPOUNDS
COATINGS
CORROSION
DISPERSIONS
ELEMENTS
HALIDES
HALOGEN COMPOUNDS
KINETICS
METALS
MIXTURES
OXIDES
OXYGEN COMPOUNDS
REACTION KINETICS
SOLUTIONS
TITANIUM COMPOUNDS
TRANSITION ELEMENT COMPOUNDS
TRANSITION ELEMENTS
360105* - Metals & Alloys- Corrosion & Erosion