Effect of LaB6 addition on mechanical properties and thermal conductivity of silicon nitride ceramics. Issue 11 (1st August 2020)

• Record Type: Journal Article
• Authors: Liang, Hanqin; Wang, Weide; Zuo, Kaihui; Xia, Yongfeng; Yao, Dongxu; Yin, Jinwei; Zeng, Yuping
• Is Part Of: Ceramics international. Volume 46:Issue 11(2020)Part A
• Page Start: 17776
• Page End: 17783
• Publication Date: 2020-08-01
• Subjects: Si3N4 -- Thermal conductivity -- LaB6 -- Bending strength; Ceramics -- Periodicals; Céramique industrielle -- Périodiques; Ceramics; Periodicals; Electronic journals; 666
• DOI: 10.1016/j.ceramint.2020.04.083
• Languages: English
• ISSNs: 0272-8842

Abstract

Abstract: Si3 N4 ceramics was hot-pressed with LaB6 –MgO as sintering additives in the temperature range from 1550 °C to 1750 °C for 2 h under the external mechanical pressure of 60 MPa, followed by post-sintering treatment at 1900 °C for 2 h under the N2 pressure of 2 MPa. The effect of sintering temperature on the densification behavior, mechanical properties, thermal conductivity, phase composition and microstructure evolution were investigated in detail. Compared to the Si3 N4 ceramics sintered with La2 O3 –MgO, the addition of LaB6 –MgO was beneficial for the improvement of fracture toughness, Vickers' hardness and thermal conductivity of Si3 N4 ceramics. The maximum Vickers' hardness of 18.98 ± 0.63 GPa was achieved at 1550 °C. The bending strength of 1039.1 ± 70.1 MPa and fracture toughness of 8.46 ± 0.23 MPa m 1/2 could be obtained at 1750 °C. After post-sintering treatment, the Si3 N4 ceramics exhibited improved thermal conductivity of 75.63 W m −1 K −1 and fracture toughness of 8.72 ± 0.11 MPa m 1/2 due to the repeated dissolution-precipitation process.