Characterization of porous sintered reaction-bonded silicon nitride containing three different rare-earth oxides
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ORIGINAL ARTICLE
Characterization of porous sintered reaction‑bonded silicon nitride containing three different rare‑earth oxides Ha‑Neul Kim1 · Mi‑Ju Kim1 · Young‑Jo Park1 · Jae‑Woong Ko1 Received: 23 March 2020 / Revised: 24 May 2020 / Accepted: 10 August 2020 © The Korean Ceramic Society 2020
Abstract The effect of rare-earth oxides on the characteristics of porous sintered reaction-bonded silicon nitride (SRBSN) was investigated. Three types of raw Si powder mixtures containing different rare-earth oxide (La2O3, Er2O3, and Yb2O3) were prepared and nitrided in the form of compacts. The nitriding profiles of the respective raw powder mixtures with elevating temperature indicated that Yb2O3 clearly promoted the nitridation of Si compacts at low temperature compared with other rare-earth oxides, and the β-Si3N4 ratio after completion of the nitriding reaction was different at which temperature the major nitridation occurred. Yb2O3 was found to be the most effective additive to achieve a strong porous SRBSN, having the flexural strength of 441 MPa. The reason why Yb2O3 promotes the nitridation reaction and has excellent mechanical properties after post-sintering is that oxygen was removed during the nitriding reaction, which was supported by the analysis of oxygen content via the laser-induced breakdown spectroscopy. Keywords Reaction-bonded silicon nitride · Rare-earth oxide · Strength · Nitridation · LIBS
1 Introduction Silicon nitride (Si3N4) is a potential candidate material for the radome application owing to the combined characteristics of relatively low dielectric constant (
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