文献类型：期刊文献

英文题名：Synthesis of Si3N4 powder with a controllable alpha/beta ratio by sol-gel assisted carbothermal reduction and nitridation

作者：Wang, Yan[1];Wang, Zeyu[1];Zhu, Zeping[1];Wang, Jiaqi[1];Meng, Ziyang[1];Wang, Deqiang[1]

机构：[1]East China Univ Sci & Technol, Sch Mat Sci & Engn, Shanghai 200237, Peoples R China

年份：2024

卷号：50

期号：18

起止页码：34164

外文期刊名：CERAMICS INTERNATIONAL

收录：;EI(收录号：20242816671988);WOS:【SCI-EXPANDED(收录号:WOS:001280598100001)】；

语种：英文

外文关键词：Phase transformation; Sol-gel processes; Whiskers

摘要：The controllable alpha/(3 ratio of Si3N4 powder was synthesized using tetraethyl orthosilicate (TEOS), glucose, MgCl2 and YCl3.6H2O by sol-gel assisted carbothermal reduction and nitridation (CRN). This study aimed to investigate the impact of various parameters, including a H2O/TEOS mol ratio of the sol, a C/Si mol ratio, sintering aids, and the temperature of CRN on the phase transformation of alpha-Si3N4. The results demonstrated that the H2O/TEOS ratio significantly influenced the relative content of alpha and (3 phase in Si3N4 by changing the morphological characteristics of SiO2. When the H2O/TEOS ratio was 100, (3-Si3N4 powder with an approximate (3 content over 88 wt% was synthesized at 1500 degrees C. This remarkable phase transformation was likely facilitated by the eutectic liquid phase consisting of MgSiO3/Mg2SiO4. The SEM image revealed rod-like whiskers with a length around 1.4 mu m for the (3-Si3N4 grains. Due to the presence of liquid phase, the synthesis of spherical-like alpha-Si3N4 nanopowder with an alpha-phase content of 91 wt% was achieved at a lower temperature of 1450 degrees C, with an H2O/ TEOS ratio of 15 and a C/Si ratio of 4. The size of the particles was about 70 nm due to the reduced reaction temperature. Furthermore, without the addition of any sintering aids or Si3N4 seeds, high purity alpha-Si3N4 with an alpha phase content approaching 96 wt% could be synthesized at 1500 degrees C, using an H2O/TEOS ratio of 15 and a C/Si ratio of 4. The resulting alpha-Si3N4 powder exhibited an extremely regular hexagonal prism shape with a length of approximately 2 mu m.