In situ synthesis and properties of self-reinforced Si$_3$N$_4$–SiO$_2$–Al$_2$O$_3$–Y$_2$O$_3$ (La$_2$O$_3$) glass–ceramic composites

[摘要] In-situ-grown $\beta$-Si$_3$N$_4$-reinforced SiO$_2$–Al$_2$O$_3$–Y$_2$O$_3$ (La$_2$O$_3$) self-reinforced glass–ceramic composites were obtained without any $\beta$-Si$_3$N$_4$ seed crystal. These composites with different compositions were prepared in a nitrogenatmosphere for comparison of phase transformation and mechanical properties. The results showed that SiO$_2$–Al$_2$O$_3$–Y$_2$O$_3$ (La$_2$O$_3$) glass can effectively promote $\alpha$- to $\beta$-Si$_3$N$_4$ phase transformation. The crystallized Y$_2$Si$_2$O$_7$–La$_{4.67}$Si$_3$O$_{13}$ phaseswith a high melting point significantly benefited the high-temperature mechanical properties of the composites. TheSi$_3$N$_4$–SiO$_2$–Al$_2$O$_3$–Y$_2$O$_3 $(La$_2$O$_3$) glass–ceramic composites exhibit excellent mechanical properties compared with unreinforcedglass–ceramic matrix, which is undoubtedly attributed to the elongated $\beta$-Si$_3$N$_4$ grains. These glass–ceramic Si$_3$N$_4$ composites with excellent comprehensive properties might be a promising material for high-temperature applications.

[学科分类] 材料工程

[关键词] Crystallization;glass–ceramics;phase transformations;silicon nitride.