β-Si_3N_4晶种的制备、性能与机理研究

Study on the Preparation,Properties and Mechnism of β-Si_3N_4 Crystal Seeds

本论文通过对β-Si3N4粉末的加入量、烧结助剂的种类及煅烧温度等参数的合理选择及优化,达到对β-Si3N4晶粒尺寸和形貌的有效控制,并探讨分析β-Si3N4晶种的反应机理。以MgO、Y2O3及SiO2为助烧剂,加入一定量的β-Si3N4粉末,通过对原始α-Si3N4粉末进行热处理,经去除掉玻璃相等漂洗工艺后,制备出相变充分、具有柱状形貌β-Si3N4晶种。重点研究了β-Si3N4粉末加入量及助烧剂种类对Si3N4相变、晶体形貌及晶粒尺寸分布的影响。研究结果表明:β-Si3N4粉末添加量10 wt%、MgO添加量5 wt%时,在1750℃下热处理1.5 h能得到具有比较理想长径比、缺陷少且晶粒尺寸与长径比分布较均匀β-Si3N4晶种,平均长径比接近于7.0。

Abstract：In the paper, the choice and optimization of the additions of β-Si3N4 powder, the species of sintering additives and sintering temperature were effective for the grain size and morphology of β-Si3N4 seeds, and reaction mechanism was also discussed. β-Si3N4 with completeness of phase transformationand rod-liked morphology was developed by means of heating the initial a-Si3N4 powder witn certmn additives of β-Si3N4 powder, MgO, Y2O3 and SiO2 and rinsing out the glass phase. The influences of β-Si3N4 contents and sintering additive species on phase transformation, grain morphology and sizedistribution were investigated. The results showed that rod-like β-Si3N4 grains with good aspect ratio and well distribution were sythesised by controlling β-Si3N4 powder with 10 wt% and MgO with 5 wt% additive contents under 1750℃ for 1.5 h, the average aspect ratio was close to 7.0.