Oxidation Behavior of NBD 200 Silicon Nitride Ceramics |
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| Authors: | Priya Mukundhan Jianqing Wu Henry H Du |
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| Affiliation: | Department of Materials Science and Engineering, Stevens Institute of Technology, Hoboken, New Jersey 07030 |
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| Abstract: | The oxidation behavior of NBD 200 Si3N4 containing 1 wt% MgO sintering aid was investigated in oxygen at 900°-1300°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 outward 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 other 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 grain-boundary diffusion of Mg2+. |
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