Influence of YAG-Based Composite Sintering Aids on Gas Pressure Sintered BN_w/Si₃N₄ Composites

Abstract:

BN_w/Si₃N₄ composites were fabricated by gas pressure sintering process using α-Si₃N₄ powder and self-made BN whisker as principal raw materials. The effects of different sintering additives such as YAG, MgO+YAG and RE₂O₃+YAG(RE=La, Sm, Dy) on the apparent porosity, microstructure, phase composition, mechanical performance and dielectric properties of the composites were analysed. The results revealed that composite sintering aids at certain ratio (MgO/RE₂O₃:YAG=1:5) was more conducive to ceramic densification than single YAG additive. The BN_w/Si₃N₄ sintered with La₂O₃+YAG acquired the highest density and the maximum bending strength (272.46 MPa) and fracture toughness(4.9 MPa·m^1/2). It was speculated that ceramic densification process was related to formation of different eutectic liquid phases with different viscosity. Additionally, when the apparent porosity of BN_w/Si₃N₄ composites was 20% or less, dielectric properties of the material were mainly influenced by the porosity and the value of the permittivity and dielectric loss decreased with the increase of ceramic porosity.

• Periodical: Key Engineering Materials (Volume 655)
• Pages: 53-57
• DOI: https://doi.org/10.4028/www.scientific.net/KEM.655.53
• Online since: July 2015
• Authors: Xian Li Wang, Hong Yu Gong*, Yu Jun Zhang, Song Wei Che
• Keywords: BN_w⁄Si₃N₄ Composites, Composite Sintering Additives, Densification, Dielectric Property, Yttrium Aluminium Garnet

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