Oxidation kinetics of hafnium carbide in the temperature range of 480 [degrees] to 600 [degrees] C

Journal Article · Thu Oct 01 04:00:00 EDT 1992 · Journal of the American Ceramic Society; (United States)

DOI:https://doi.org/10.1111/j.1151-2916.1992.tb05487.x· OSTI ID:6973140

Shimada, S; Inagaki, M ^[1]; Matsui, K ^[2]

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1. Dept. of Applied Chemistry, Faculty of Engineering, Hokkaido Univ., Sapporo 060 (Japan)
2. Central Research Lab., Idemitsu Kosan Co., Ltd., Sodegaura Chiba 299-02 (Japan)

This paper reports on the isothermal oxidation of HfC powders which was carried out at temperatures of 480[degrees] C to 600[degrees] C at oxygen pressures of 4, 8, and 16 kPa, using an electromicrobalance. The oxidized product was identified by X-ray analysis, Raman spectroscopy, X-ray photoelectron spectroscopy, and electron diffraction, and the morphology of the oxidized grains was observed by scanning electron microscopy. Oxidation proceeds by two processes: a diffusion-controlled process operates up to about 50% oxidation and a phase-boundary-controlled process operates above about 50% oxidation. The activation energies for both processes are the same (197 [plus minus] 15 kJ [center dot] mol[sup [minus] 1]). The change in the oxidation process is associated with the generation of cracks on the grains, resulting from the growth or expansion stress due to the formation of monoclinic HfO[sub 2] microcrystallites less than 3 nm in size.

• OSTI ID: 6973140
• Journal Information: Journal of the American Ceramic Society; (United States), Journal Name: Journal of the American Ceramic Society; (United States) Vol. 75:10; ISSN 0002-7820; ISSN JACTAW
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360205* -- Ceramics
Cermets
& Refractories-- Corrosion & Erosion
ACTIVATION ENERGY
CARBIDES
CARBON COMPOUNDS
CHEMICAL REACTIONS
COHERENT SCATTERING
CRACKS
CRYSTAL STRUCTURE
DIFFRACTION
DIFFUSION
ELECTROMAGNETIC RADIATION
ELECTRON DIFFRACTION
ELECTRON MICROSCOPY
ELECTRON SPECTROSCOPY
ELEMENTS
ENERGY
GRAIN SIZE
HAFNIUM CARBIDES
HAFNIUM COMPOUNDS
IONIZING RADIATIONS
ISOTHERMAL PROCESSES
MICROSCOPY
MICROSTRUCTURE
MORPHOLOGY
NONMETALS
OXIDATION
OXYGEN
PHOTOELECTRON SPECTROSCOPY
RADIATIONS
RAMAN SPECTRA
REFRACTORY METAL COMPOUNDS
SCANNING ELECTRON MICROSCOPY
SCATTERING
SIZE
SPECTRA
SPECTROSCOPY
TEMPERATURE RANGE
TEMPERATURE RANGE 0400-1000 K
TRANSITION ELEMENT COMPOUNDS
VERY HIGH PRESSURE
X RADIATION
X-RAY DIFFRACTION