HIGH TEMPERATURE OXIDATION OF NIOBIUM. Technical (Scientific) Note No. 2 for April 1, 1959 to March 31, 1960

Technical Report · Fri Apr 01 04:00:00 EST 1960

OSTI ID:4141608

Kofstad, P; Kjollesdal, H; Markali, J; Norman, N

The oxidation behavior of Nb was studied at 500 to 1200 deg C and at O pressures of 760, 100, 10, 1, and 0.1 mm of Hg. Kinetic studies of the oxidation and structural investigations of the oxidized specimens were performed by means of x-ray diffraction, electron diffraction, electron microrcopy. and metallographic techniques. Reversals in the temperature coefficient of the oxidation were found in two temperature regions (at about 600 and 800 deg C) depending upon the O pressure. The complex oxidation behavior is suggested to be due to formation of different Nb/sub2/O/sub 5/ modifications in different temperature regions. and to the ability of the oxide to deform plastically and form protecting scales with decreasing O pressure. In addition to oxide scale formation, O is dissolved in the metal during the oxidation. Growth of oxide whiskers consisting of single crystals of alpha --Nb/sub 2/O/sub 5/ was found to take place on the oxide surface at temperatures above approximately 800 deg C. (auth)

• Research Organization: Central Inst. for Industrial Research, Blindern, Norway
• NSA Number: NSA-14-024485
• OSTI ID: 4141608
• Report Number(s): NP-9061; SI-Publ.-282
• Country of Publication: United States
• Language: English

Related Subjects

CRYSTALS
DIFFRACTION
ELECTRON MICROSCOPY
ELECTRONS
HIGH TEMPERATURE
LATTICES
METALLOGRAPHY
METALS, CERAMICS, AND OTHER MATERIALS
NIOBIUM
NIOBIUM OXIDES
OXIDATION
OXYGEN
PRESSURE
REACTION KINETICS
SURFACES
X RADIATION