β-Si_3N_4晶种对Si_3N_4陶瓷力学性能和显微结构的影响  

The Effects of β-Si_3N_4 Seeds on the Mechanical Properties and Microstructure of Silicon Nitride Ceramics

作　　者：刘亚[1] 李瑞锋[1] 叶飞[1] 郭露村[1] 

机构地区：[1]南京工业大学材料科学与工程学院,江苏南京210009

出　　处：《陶瓷学报》2012年第4期430-436,共7页Journal of Ceramics

基　　金：江苏省科技支撑计划(编号:BE2009169)

摘　　要：采用无压烧结工艺制备了长柱状β-Si3N4晶种。研究了晶种尺寸对Si3N4陶瓷力学性能和显微结构的影响。结果表明:在1750℃通过控制保温时间(1h、1.5h和2h)可获得不同尺寸的长柱状β-Si3N4晶种。Si3N4陶瓷加入晶种后,其相对密度和抗弯强度虽略有降低,但断裂韧性得到大幅提高。平均长度为4.51μm,长径比为5.71的晶种对Si3N4陶瓷的增韧效果最佳;且随着其添加量的增加,Si3N4陶瓷的断裂韧性先升高再降低,当掺量为2wt%时断裂韧性达到最高(提高了20%以上)。显微结构分析表明,Si3N4陶瓷断裂韧性的提高,与因晶种加入而导致的Si3N4晶粒长径比和大长柱状晶粒含量的增加有关。The various rodlike β-Si3N4 seeds were prepared by pressureless sintedng at 1750℃ for 1 hour, 1.5 hours and 2 hours. The effects of seed crystal size on the mechanical properties and microstructure of silicon nitride ceramics were investigated. The experimental results showed that the fracture toughness of silicon nitride was improved significantly with the addition of the seeds, while the relative density and bending strength were decreased slightly. As the length and the aspect ratio of seeds were 4.51μm and 5.71, respectively, the optimum toughening efficiency was obtained. In addition, the fracture toughness initially increased and then decreased with the increasing of seeds amount. When the content of β-Si3N4 seeds was 2wt%, the highest fracture toughness was achieved （improved by more than 20%）. Based on the analysis of the microstructure, the increase of the fracture toughness was related to the increase of the aspect ratio of silicon nitride grains and the content of large elongated β-Si3N4 grains.

关 键 词：SI3N4陶瓷 晶种 长径比 力学性能 显微结构 

分 类 号：TQ174.75[化学工程—陶瓷工业]