OXIDATION OF NIOBIUM IN THE TEMPERATURE RANGE 350-750 C
S> The kinetics of the oxidation of niobium in dry oxygen at 1 atm pressure were measured at temperatures in the range 350 to750 deg C with some additional measurements at 0.1 atm. At 350 deg C, in tests lasting 270 hr, the oxidation is protective, but at 400 deg C and above the metal oxidizes, after an initial period, at a constant rate with a second breakaway reaction (rate transition) at 450 and 500 deg C but not at higher temperatures. The anomalous temperature coefficient of the linear rate was confirmed. The specific surface of the oxide scale was measured and, apart from an anomaly at 400 deg C, is shown to decrease with increasing temperature of oxidation and this is ascribed to sintering. The oxidation kinetics of a purer batch of niobium were also investigated. The effect of moisture is to decrease the rate at 400 and 450 deg C, whereas at 600 deg C the rate is unchanged. (auth)
- Research Organization:
- Univ. of Exeter, Eng.
- Sponsoring Organization:
- USDOE
- NSA Number:
- NSA-14-015637
- OSTI ID:
- 4156061
- Journal Information:
- Journal of the Electrochemical Society (U.S.) Absorbed Electrochem. Technol., Journal Name: Journal of the Electrochemical Society (U.S.) Absorbed Electrochem. Technol. Vol. Vol: 107; ISSN JESOA
- Country of Publication:
- Country unknown/Code not available
- Language:
- English
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