无压烧结氮化硅陶瓷的致密化过程  

Densification process of pressureless sintered silicon nitride ceramics

作　　者：刘文勇 李建斌 孙振飞 蒋强国[1] LIU Wenyong;LI Jianbin;SUN Zhenfei;JIANG Qiangguo(Research Center for Advanced Machining Tools and High Technology Ceramics,Guangdong University of Technology,Guangzhou 510006,China)

机构地区：[1]广东工业大学先进加工工具与高技术陶瓷研究中心,广州510006

出　　处：《粉末冶金材料科学与工程》2020年第3期191-196,共6页Materials Science and Engineering of Powder Metallurgy

基　　金：国家重点研发计划资助项目(2017YFB0310600);国家自然科学基金青年基金资助项目(51602059);广东省“珠江人才计划”本土创新科研团队项目(2017BT01C169)。

摘　　要：在陶瓷粉末中添加Al2O3-Y2O3作为助烧剂,经过干压和冷等静压成形,然后无压烧结制备Si3N4陶瓷,通过TOM-AC实时观测烧结过程中Si3N4陶瓷样品的收缩和致密度变化;分析不同温度烧结的陶瓷结构与形貌,并研究Si3N4陶瓷的致密化过程。结果表明:1400℃时α-Si3N4开始转变为β-Si3N4,在1400~1600℃范围内致密度快速增大,且压坯密度越高,致密化速率越快。烧结温度高于1600℃时,α-Si3N4全部转变为β-Si3N4柱状晶,晶粒明显长大,致密化速率降低。压坯密度对最终的烧结致密度影响不大。由此确定最佳烧结工艺为1650℃与1800℃分别保温2 h,所得Si3N4陶瓷的致密度为98.4%,硬度(HV10)为15.7±0.5 GPa,抗弯强度和断裂韧性分别为1037.3±48.9 MPa和5.8±0.2 MPa·m&1/2。Silicon nitride ceramics were prepared by pressureless sintering,with Al2O3-Y2O3 as sintering aids,after dry pressing and cold isostatic pressing.The shrinkage and densification of Si3N4 ceramics was observed in real time with TOM-AC high temperature sintering equipment.Meanwhile,the densification process of Si3N4 ceramics was studied by analyzing the structure and morphology of ceramics sintered at different temperatures.The results show thatα-Si3N4 begins to transform intoβ-Si3N4 at 1400℃.The density increases rapidly in the range of 1400−1600℃,and the higher the density of compact,the faster the densification rate.When the sintering temperature is higher than 1600℃,α-Si3N4 transforms intoβ-Si3N4 columnar crystal completely,and the crystal grain grows obviously,while the densification rate decreases.The compacts density has little effect on the final sintering density.The optimal sintering process is sintering at 1650℃and 1800℃for 2 h respectively.The density of Si3N4 ceramics is 98.4%,and the hardness(HV10)is 15.7±0.5 GPa.The bending strength and fracture toughness are 1037.3±48.9 MPa and 5.8±0.2 MPa·m^1/2,respectively.

关 键 词：SI3N4陶瓷 无压烧结 收缩 致密化过程 TOM-AC 

分 类 号：TQ174[化学工程—陶瓷工业]