Oxidation behavior of NBD 200 silicon nitride ceramics

Authors
Mukundhan, P Wu, JQ Du, HH
Citation
P. Mukundhan et al., Oxidation behavior of NBD 200 silicon nitride ceramics, J AM CERAM, 82(8), 1999, pp. 2260-2262
Citations number
7
Categorie Soggetti
Apllied Physucs/Condensed Matter/Materiales Science","Material Science & Engineering
Journal title
JOURNAL OF THE AMERICAN CERAMIC SOCIETY
ISSN journal
00027820 → ACNP
Volume
82
Issue
8
Year of publication
1999
Pages
2260 - 2262
Database
ISI
SICI code
0002-7820(199908)82:8<2260:OBON2S>2.0.ZU;2-5
Abstract
The oxidation behavior of NBD 200 Si3N4 containing 1 wt% MgO sintering aid was investigated in oxygen at 900 degrees-1300 degrees C. The oxide growth followed a parabolic rate law with an apparent activation energy of 260 kJ/ mol. The oxide layers were enriched with sodium and magnesium because of ou tward diffusion of intergranular Na+ and Mg2+ cations in the ceramics. The 2-4 orders of magnitude higher oxidation rate for NBD 200 Si3N4 than for ot her Si3N4 ceramics with a similar amount of MgO could be attributed to the presence of sodium. The oxidation process was most likely rate limited by g rain-boundary diffusion of Mg2+.