TY - JOUR
T1 - Effect of pre-oxidation on the microstructure, mechanical and dielectric properties of highly porous silicon nitride ceramics
AU - Zhang, Rubing
AU - Fang, Daining
AU - Chen, Xiangmeng
AU - Pei, Yongmao
PY - 2012/9
Y1 - 2012/9
N2 - Highly porous Si 3N 4 ceramics have been fabricated via freeze casting and sintering. The as-sintered samples were pre-oxidized at 1200-1400 °C for 15 min. The effect of pre-oxidation temperature on the microstructure, flexural strength, and dielectric properties of porous Si 3N 4 ceramics were investigated. As the pre-oxidation temperature increased from 1200 °C to 1400 °C, firstly, the flexural strength of the pre-oxidized specimens remained almost constant at 1200 °C, and then decreased to 14.2 MPa at 1300 °C, but finally increased to 25.6 MPa at 1400 °C, while the dielectric constant decreased gradually over the frequencies ranging from 8.2 GHz to 12.4 GHz. This simple process allows porous Si 3N 4 ceramics to have ultra-low dielectric constant and moderate strength, which will be feasible in broadband radome applications at high temperatures.
AB - Highly porous Si 3N 4 ceramics have been fabricated via freeze casting and sintering. The as-sintered samples were pre-oxidized at 1200-1400 °C for 15 min. The effect of pre-oxidation temperature on the microstructure, flexural strength, and dielectric properties of porous Si 3N 4 ceramics were investigated. As the pre-oxidation temperature increased from 1200 °C to 1400 °C, firstly, the flexural strength of the pre-oxidized specimens remained almost constant at 1200 °C, and then decreased to 14.2 MPa at 1300 °C, but finally increased to 25.6 MPa at 1400 °C, while the dielectric constant decreased gradually over the frequencies ranging from 8.2 GHz to 12.4 GHz. This simple process allows porous Si 3N 4 ceramics to have ultra-low dielectric constant and moderate strength, which will be feasible in broadband radome applications at high temperatures.
KW - B. Porosity
KW - C. Dielectric properties
KW - C. Mechanical properties
KW - D. Si N
UR - http://www.scopus.com/inward/record.url?scp=84862683214&partnerID=8YFLogxK
U2 - 10.1016/j.ceramint.2012.03.056
DO - 10.1016/j.ceramint.2012.03.056
M3 - Article
AN - SCOPUS:84862683214
SN - 0272-8842
VL - 38
SP - 6021
EP - 6026
JO - Ceramics International
JF - Ceramics International
IS - 7
ER -