Modification and Control of Oxide Structures on Metals and Alloys
Abstract
The feasibility of modifying oxide defect structures to enhance oxidation protection of elevated temperature structural materials was investigated. High-pressure, high-temperature techniques and pre-oxidation treatments were used to modify the oxide structure. Nb2O5 when subjected to high pressures (78 kbar) and high temperatures transformed to a denser structure with a density increase of about 25%. Nb, Ta, and the niobium alloy, B-1 (Nb-15Ti- 10Ta-10W-2Hf-2.5Al) were pretreated in an autoclave containing Fe(3+) ions and a mixed oxide, rutile type tapiolite structure was formed. These films decreased the initial oxidation rate of pure niobium in 20 torr oxygen at 650C. However, the films caused an increased oxidation rate for pure niobium and tantalum in air at 1060C when compared to the untreated metals. The oxidation behavior of the B-1 niobium alloy at 1060C in air was enhanced by a 3-4 hour pre-exposure in 20 torr oxygen at 650C. Metallographic and x-ray analyses indicated that less TiO2 was formed in the oxide film grown on these samples. In addition, many techniques reported in the literature for altering the oxidation behavior of various metal and alloy systems were reviewed.
Document Details
- Document Type
- Technical Report
- Publication Date
- Apr 01, 1971
- Accession Number
- AD0728028
Entities
People
- Robert C. Svedberg