Vapour transport of magnesia into reaction-bonded silicon nitride
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Magnesia, as a sintering additive, can be introduced into reaction-bonded silicon nitride (RBSN) via vapours-phase transport. The principal process variables were studied; a controlling factor was found to be the amount of silica on the internal surfaces of the ceramic. Through a controlled oxidation of the RBSN, the amount of magnesia introduced to the compact was increased to ≈2 wt% allowing a post-sintered density of 93% theoretical to be achieved. Further increases in internal oxidation, and consequent magnesia uptake, were limited by the oxidation of Si3N4 whiskers on the surface of the RBSN and in its pore structure.
KeywordsOxidation Polymer Silicon Magnesia Nitride
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- 2.J. A. Mangels, in “Progress in Nitrogen Ceramics”, edited by F. L. Riley (Martinuus Nijhoff, 1983) p. 231.Google Scholar
- 3.P. L. Antora, A. Giachello and P. C. Martinengo, in “Ceramic Powders”, edited by P. Vincenzeni (Elsevier, 1983) p. 753.Google Scholar
- 6.M. D. Pugh, PhD Thesis, University of Leeds (1986).Google Scholar
- 7.T. Sata, J. Sasamoto, M. Lee and E. Maeda, Rev. Int. Haut. Temp. Refract. 15 (1978) 237.Google Scholar
- 8.J. M. Vieira, PhD Thesis, University of Leeds (1981).Google Scholar
- 13.E. M. Levin, C. R. Robbins and H. F. McMurdie, in “Phase Diagrams for Ceramists”, edited by M. K. Rester (American Ceramic Society, 1964) Fig. 712.Google Scholar
- 14.G. Grathwohl and F. Thümmler, in “Progress in Nitrogen Ceramics”, edited by F. L. Riley (Martinuus Nijhoff, 1983) p. 547.Google Scholar