Papers by Keyword: RBSN

Abstract: A cost-effective route to synthesize β-SiAlONs from Si mixture by reaction bonding followed by post-sintering was investigated. Three different z values, 0.45, 0.92 and 1.87 in Si6-zAlzOzN8-z, without excess liquid phase were selected to elucidate the mechanism of both SiAlON formation and densification. For the RBSN(reaction-bonded silicon nitride) specimens, nitridation rate of more than 90% was achieved by multistep heating up to 1400oC in flowing 5%H2-95%N2 and residual Si was not detected by XRD analysis. Increase in density was observed with z values for the post-sintered specimens and this tendency was well explained by the presence of higher amount of transient liquid phase with larger z values. Measured z values of the synthesized -SiAlONs were nearly similar to calculated values using starting compositions. The slight deviation in the two z values was successfully explained by the reasonable assessment of nitriding and post-sintering process.

Abstract: The interaction between gas atmosphere and silicon during reaction bonded silicon nitride(RBSN)process leads to a non-uniform band formation of alpha silicon nitride. The reaction layer, α -Si3N4, was formed near the surface of the sample in the early stage of RBSN. Reactive nitrogen gas was supplied as static state using computer controlled gas delivery system. The formation of α -Si3N4 band near the surface of the sample can be explained thermodynamically, based on the nitrogen partial pressure in the gas mixtures.

Abstract: Prediction of porosity level for the Si3N4 filter substrate manufactured by reaction bonding of Si compact and subsequent post-sintering was attempted and its validity was verified by comparison between calculation and measurement. Both are well matched in the specimens of asnitrided and low temperature post-sintering, while few percents higher measurement in high temperature post-sintered specimens resulted from weight loss during the process.