Chapter 1. Nitriding Kinetics of Si-SiC Powder Mixtures as Simulations of Reaction Bonded Si3N4-SiC Composites
- John B. Wachtman Jr.
Published Online: 28 MAR 2008
Copyright © 1989 The American Ceramic Society, Inc.
A Collection of Papers Presented at the 13th Annual Conference on Composites and Advanced Ceramic Materials, Part 2 of 2: Ceramic Engineering and Science Proceedings, Volume 10, Issue 9/10
How to Cite
Lightfoot, A., Sheldon, B. W., Flint, J. H. and Haggerty, J. S. (1989) Nitriding Kinetics of Si-SiC Powder Mixtures as Simulations of Reaction Bonded Si3N4-SiC Composites, in A Collection of Papers Presented at the 13th Annual Conference on Composites and Advanced Ceramic Materials, Part 2 of 2: Ceramic Engineering and Science Proceedings, Volume 10, Issue 9/10 (ed J. B. Wachtman), John Wiley & Sons, Inc., Hoboken, NJ, USA. doi: 10.1002/9780470310588.ch1
- Published Online: 28 MAR 2008
- Published Print: 1 JAN 1989
Print ISBN: 9780470374870
Online ISBN: 9780470310588
- nitriding kinetics;
- sic powder mixlures;
- ceramic materials;
- temperature properties;
- crystalline matrices
The nitriding kinetics of Si and Si plus SiC powder mixtures were studied to simulate the fabrication of RBSN-SiC ceramic matrix composites. Very clean, assynthesized, and solvent-exposed powders were studied; C-rich and Si-rich SiC 0.04–0.05 μm diameter powders were mixed in varying concentrations with SiH4-derived 0.2–0.3 μm diameter Si powder. Reactions were monitored with TGA and samples were characterized by SEM and X-ray diffraction. Although all exposures inhibited the nitriding kinetics from rates observed with the as-synthesized Si powders, complete conversion was still achieved with nitriding schedules that permit fabrication of composites. For example, complete nitridation is achieved with C-rich SiC powders in 140 min at 1250°C, and in the centers of Si-rich SiC powders in 15 min. The effects on the incubation periods, fast reaction periods, and slow reaction periods that characterize these nitriding processes were studied to explain unusual reverse reaction gradients and other effects of contamination.