THE OXIDATION AND CORROSION OF NIOBIUM (COLUMBIUM)

Journal Article · Fri Feb 01 04:00:00 EST 1963 · Trans. AIME

OSTI ID:4696517

Cox, B; Johnston, T

The results of oxidation and corrosion experiments on niobium in oxygen and steam at temperatures of 350 to 650 un. Concent 85% C, and in dilute sulfate solutions at 300 un. Concent 85% C are presented. The oxidation of niobium in oxygen can be explained in terms of a pretransition period, which obeys an approximately parabolic rate law, and a post-transition period in which a more rapid linear rate is partially stifled by restriction of the gas flow due to the growth of the porous outer film. In water vapor the oxidation of niobium follows a parabolic rate law and does not show a transition to linear kientics. The higher oxide, Nb/sub 2/O/sub 5/, was usually absent from the NbO/NbO/sub 2/ film which was formed. The addition of a small partial pressure of oxygen to the water vapor resulted in accelerated oxidation according to the normal kinetics for oxidation in oxygen. The theory that nucleation of Nb/sub 2/O/sub 5/ on the surface of the protective NbO/NbO/sub 2/ film is the cause of the accelerated oxidation was supported. After oxidation in steam at high pressure Nb/sub 2/O/ sub 5/ was found in the protective film. The kinetics of oxidation in oxygenated aqueous solutions at 300 un. Concent 85% C were similar to those for oxidation in oxygen. (P.C.H.)

• Research Organization: Atomic Energy Research Establishment, Harwell, Berks, Eng.
• NSA Number: NSA-17-020426
• OSTI ID: 4696517
• Report Number(s): NP-12029
• Journal Information: Trans. AIME, Journal Name: Trans. AIME Vol. Vol: 227
• Country of Publication: Country unknown/Code not available
• Language: English

Related Subjects

CORROSION
EXPANSION
FILMS
GAS FLOW
HIGH TEMPERATURE
METALS, CERAMICS, AND OTHER MATERIALS
NIOBIUM
NIOBIUM OXIDES
OXIDATION
OXYGEN
POROSITY
PRESSURE
REACTION KINETICS
SOLUTIONS
STEAM
TEMPERATURE
WATER