Fabrication and Properties of Pressureless Sintered Si3N4/BN Composite Ceramics with La2O3-Al2O3-Y2O3 as Sintering Additives
With commercial α-Si3N4 and h-BN powders as starting materials, La2O3, Al2O3, Y2O3 as sintering additives, Si3N4/BN composite ceramics with 25vo1% h-BN were fabricated by pressureless sintering. Various amounts of La2O3 (0, 2, 4, 8, 15wt%) were added, with constant Y2O3/Al2O3 weight ratio and additives (Y2O3/Al2O3/La2O3) amount. The densification behaviors,α-β transformation and room-temperature strength of Si3N4/BN composite were investigated. The porosity of samples decreased with La2O3 content increasing, and the lowest porosity of 20.83% was observed for samples containing 4wt% La2O3, then leaded to an increase. The flexural strength of all the specimens increased with the addition up to 4wt% and changed greatly thereafter. The highest room-temperature flexural strength, 272.4MPa, was obtained when 4wt% La2O3 was added.Results of XRD patterns revealed that β-Si3N4 and h-BN existed in all the specimens. No α-Si3N4 was detected, implying that a-to β-Si3N4 transformation has been completed during the pressureless sintering process. These results show that the La2O3-Al2O3-Y2O3 system can act as effective sintering additives for pressureless sintered Si3N4/BN composite.
silicon nitride boron nitride pressureless sintering La2O3-Al2O3-Y2O3
Yongfeng Li Ping Liu Guanjun Qiao Jianfeng Yang Haiyun Jin Xiangdong Wang
State Key Laboratory for Mechanical Behavior of Materials, Xian Jiaotong University, Xian,Shaanxi, School of Electrical Engineering, Xian Jiaotong University, Xian, Shaanxi, 710049 China School of Science.Xian Jiaotona University.Xian.Shaanxi.710049 China
国际会议
10th International Symposium on Eco-Materials Processing and Design(第10届国际生态材料加工与设计研讨会)
西安
英文
761-764
2009-01-13（万方平台首次上网日期，不代表论文的发表时间）