High Temperature Passive Oxidation Mechanism of CVD SiC

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The passive oxidation mechanism of CVD SiC was discussed from experimental results with high-temperature thermogravimetry and thermodynamic analyses. The bubble formation temperature around 1900 K could be too low for an oxygen inward diffusion limited process but conform to a CO outward diffusion limited process. The parabolic rate constant (kp) had weak oxygen partial pressure (PO2) dependence, kp ∝ PO2 n where n = 0.09 to 0.12. These n values may be consistent with the CO outward diffusion limited process. The activation energy of kp obtained in the present study, 210 kJ/mol, could suggest a different mechanism from the well-approved oxygen molecule permeation limited process at lower temperatures below 1600 K. Amorphous phase was significantly contained in SiO2 scales formed in an N2-O2 atmosphere. No effect of the amorphous formation on kp was identified.

Info:

Periodical:

Materials Science Forum (Volumes 522-523)

Edited by:

Shigeji Taniguchi, Toshio Maruyama, Masayuki Yoshiba, Nobuo Otsuka and Yuuzou Kawahara

Pages:

27-36

DOI:

10.4028/www.scientific.net/MSF.522-523.27

Citation:

T. Goto, "High Temperature Passive Oxidation Mechanism of CVD SiC", Materials Science Forum, Vols. 522-523, pp. 27-36, 2006

Online since:

August 2006

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$35.00

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