Identification of crevice corrosion in the titanium alloy TiCode-12 in simulated rock salt brine at 150/sup 0/C. [Ti-0. 3Mo-0. 8Ni]
TiCode-12 (Ti-0.3Mo-0.8Ni) is a prime corrosion-resistant material for high-level nuclear-waste containers which will be emplaced in mined geologic repositories such as those in rock salt. The crevice corrosion behavior of this alloy was investigated in simulated rock salt brine solutions at a temperature of 150/sup 0/C. A distinct corrosion product with a range of interference colors was observed in a mechanically simulated crevice after two to four-weeks' exposure. Low pH accelerated the reaction rate and deaerated solutions give less corrosion than aerated ones. Also, increasing specimen size, decreasing crevice gap, and preoxidation of the cathodic area gave more voluminous corrosion products inside the crevice. High temperature did not necessarily accelerate crevice corrosion. These results are consistent with those expected from macroscopic concentration cell formation accompanied by oxygen depletion, potential drop, and acidification inside the crevice. TEM and SEM techniques were extensively utilized to identify the film formed inside the crevice at each stage of the corrosion process. Based on the study, and pH and potential measurements inside the crevice of commercially pure titanium done by other workers, a mechanism for crevice corrosion in TiCode-12 has been developed. It involves the initial formation of compact anatase crystals inside the crevice.As the macroscopic cell develops further, it is postulated that either the anatase form of TiO/sub 2/ will transform to the lower oxide Ti/sub 3/O/sub 5/ and to the rutile form of TiO/sub 2/, or titanium dissolves into the solution after the breakdown of the protective film and subsequent hydrolysis takes place to form the lower oxide and the rutile form of TiO/sub 2/. The role of alloying elements (Mo and Ni) and dissolved solutes are discussed with respect to these postulations. 10 figures, 3 tables.
- Research Organization:
- Brookhaven National Lab., Upton, NY (USA)
- DOE Contract Number:
- AC02-76CH00016
- OSTI ID:
- 6652729
- Report Number(s):
- BNL-NUREG-32107; CONF-820955-2; ON: DE83002819
- Resource Relation:
- Conference: ASTM conference on titanium and zirconium in industrial applications, New Orleans, LA, USA, 21 Sep 1982
- Country of Publication:
- United States
- Language:
- English
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Crevice corrosion of titanium alloy TiCode-12 in simulated rock salt brine at 150/sup 0/C
Related Subjects
12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE WASTES FROM NUCLEAR FACILITIES
42 ENGINEERING
BRINES
CORROSIVE EFFECTS
CONTAINERS
MATERIALS TESTING
RADIOACTIVE WASTE DISPOSAL
TITANIUM BASE ALLOYS
CREVICE CORROSION
EXPERIMENTAL DATA
HIGH TEMPERATURE
PH VALUE
RUTILE
SALT DEPOSITS
SCANNING ELECTRON MICROSCOPY
TITANIUM OXIDES
TRANSMISSION ELECTRON MICROSCOPY
ALLOYS
CHALCOGENIDES
CHEMICAL REACTIONS
CORROSION
DATA
ELECTRON MICROSCOPY
GEOLOGIC DEPOSITS
INFORMATION
MANAGEMENT
MATERIALS
MICROSCOPY
MINERALS
NUMERICAL DATA
OXIDE MINERALS
OXIDES
OXYGEN COMPOUNDS
RADIOACTIVE MATERIALS
RADIOACTIVE MINERALS
TESTING
TITANIUM ALLOYS
TITANIUM COMPOUNDS
TRANSITION ELEMENT COMPOUNDS
WASTE DISPOSAL
WASTE MANAGEMENT
360105* - Metals & Alloys- Corrosion & Erosion
052002 - Nuclear Fuels- Waste Disposal & Storage
420204 - Engineering- Shipping Containers