OXIDATION OF SINGLE-CRYSTAL AND POLYCRYSTALLINE ZIRCONIUM

Journal Article · Tue Oct 01 04:00:00 EDT 1963 · Trans. AIME

OSTI ID:4640759

Mackay, T L

Oxidation rates of single-crystal and polycrystalline zirconium in oxygen at temperatures from 307 to 815 deg C obey the parabolic rate law for short exposure time, 4 to 6 hr. The activation energy for the oxidation of singlecrystal zirconium between 420 and 790 deg C is 42.6 plus or minus 0.7 kcal per mole, and in the temperature range 307 to 600 deg C the activation energy for oxidation of polycrystalline zirconium is approximately the same. The high-activation energy is indicative that diffusion through the bulk oxide film is the primary mode of mass transport for both types of metal. The higher oxidation rates for polycrystalline zirconium in this temperature range were attributed to differences in the orientation of the grains in the metal with respect to the oxidizing surfaces. Above 600 deg C, grain growth was observed in polycrystalline zirconium, and the oxidation rates approached those of single- crystal zirconium. (auth)

• Research Organization: Atomics International, Canoga Park, Calif.
• NSA Number: NSA-17-039613
• OSTI ID: 4640759
• Journal Information: Trans. AIME, Journal Name: Trans. AIME Vol. Vol: 227
• Country of Publication: Country unknown/Code not available
• Language: English

Related Subjects

ACTIVATION ENERGY
DIFFUSION
FILMS
GRAIN SIZE
METALS, CERAMICS, AND OTHER MATERIALS
MONOCRYSTALS
OXIDATION
OXIDES
OXYGEN
REACTION KINETICS
SURFACES
TEMPERATURE
THERMODYNAMICS
ZIRCONIUM