| Fabrication of β-SiAlONs by a Reaction-Bonding Process Followed by Post-Sintering |
| Young-Jo Park, Eun-Ah Noh, Jae-Woong Ko, Hai-Doo Kim |
| Engineering Ceramics Research Group, Korea Institute of Materials Science |
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| ABSTRACT |
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A cost-effective route to synthesize $beta$-SiAlONs from Si mixtures by reaction bonding followed by post-sintering was investigated. Three different z values, 0.45, 0.92 and 1.87, in $Si_{6-z}Al_zO_zN_{8-z}$ without excess liquid phase were selected to elucidate the mechanism of SiAlON formation and densification. For RBSN (reaction-bonded silicon nitride) specimens prior to post-sintering, nitridation rates of more than 90% were achieved by multistep heating to $1400^{circ}C$ in flowing 5%$H_2$/95%$N_2$; residual Si was not detected by XRD analysis. An increase in density was acquired with increasing z values in post-sintered specimens, and this tendency was explained by the presence of higher amounts of transient liquid phase at larger z values. Measured z values from the synthesized $beta$-SiAlONs were similar to the values calculated for the starting compositions. Slight deviations in z values between measurements and calculations were rationalized by a reasonable application of the characteristics of the nitriding and post-sintering processes. |
| Key words:
SiAlON, Silicon nitride, Reaction-bonding, Nitriding, Post-sintering |
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