Microstructure and Dielectric Properties of LPCVD/CVI-SiBCN Ceramics Annealed at Different Temperatures

Jianping Li; Mingxi Zhao; Yongsheng Liu; Nan Chai; Fang Ye; Hailong Qin; Laifei Cheng; Litong Zhang

doi:10.3390/ma10060655

Microstructure and Dielectric Properties of LPCVD/CVI-SiBCN Ceramics Annealed at Different Temperatures

Materials (Basel). 2017 Jun 15;10(6):655. doi: 10.3390/ma10060655.

Authors

Jianping Li¹, Mingxi Zhao², Yongsheng Liu^{3

4}, Nan Chai⁵, Fang Ye⁶, Hailong Qin⁷, Laifei Cheng⁸, Litong Zhang⁹

Affiliations

¹ Science and Technology on Thermostructural Composite Materials Laboratory, Northwestern Polytechnical University, Xi'an 710072, China. ijianping@163.com.
² Science and Technology on Thermostructural Composite Materials Laboratory, Northwestern Polytechnical University, Xi'an 710072, China. mingxizhao@mail.nwpu.edu.cn.
³ Science and Technology on Thermostructural Composite Materials Laboratory, Northwestern Polytechnical University, Xi'an 710072, China. yongshengliu@nwpu.edu.cn.
⁴ State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xi'an 710072, China. yongshengliu@nwpu.edu.cn.
⁵ Science and Technology on Thermostructural Composite Materials Laboratory, Northwestern Polytechnical University, Xi'an 710072, China. chainan.90@163.com.
⁶ Science and Technology on Thermostructural Composite Materials Laboratory, Northwestern Polytechnical University, Xi'an 710072, China. yefang511@nwpu.edu.cn.
⁷ Science and Technology on Thermostructural Composite Materials Laboratory, Northwestern Polytechnical University, Xi'an 710072, China. qinxlong555@163.com.
⁸ Science and Technology on Thermostructural Composite Materials Laboratory, Northwestern Polytechnical University, Xi'an 710072, China. chenglf@nwpu.edu.cn.
⁹ Science and Technology on Thermostructural Composite Materials Laboratory, Northwestern Polytechnical University, Xi'an 710072, China. zhanglt@nwpu.edu.cn.

Abstract

SiBCN ceramics were introduced into porous Si₃N₄ ceramics via a low-pressure chemical vapor deposition and infiltration (LPCVD/CVI) technique, and then the composite ceramics were heat-treated from 1400 °C to 1700 °C in a N₂ atmosphere. The effects of annealing temperatures on microstructure, phase evolution, dielectric properties of SiBCN ceramics were investigated. The results revealed that α-Si₃N₄ and free carbon were separated below 1700 °C, and then SiC grains formed in the SiBCN ceramic matrix after annealing at 1700 °C through a phase-reaction between free carbon and α-Si₃N₄. The average dielectric loss of composites increased from 0 to 0.03 due to the formation of dispersive SiC grains and the increase of grain boundaries.

Keywords: chemical vapor deposition and infiltration; dielectric properties; electromagnetic wave absorbing properties; heat treatment; siliconboron carbonitride ceramic.