Dielectric Properties of Porous Si3N4 Ceramics Prepared by In Situ Cordierite Bonding

2010 ◽  
Vol 434-435 ◽  
pp. 701-704
Author(s):  
Yong Feng Xia ◽  
Yu Ping Zeng ◽  
Dong Liang Jiang
Keyword(s):  
Dielectric Constant ◽  
Phase Composition ◽  
Dielectric Properties ◽  
Sintering Temperature ◽  
Porous Si ◽  
Porous Si3n4 ◽  
Ceramic Process ◽  
Si3n4 Ceramics ◽  
Porous Si3n4 Ceramics

In situ bonding porous silicon nitride (Si3N4) ceramics were fabricated in air using a conventional ceramic process using Si3N4, Al2O3 and MgO as the starting materials. The effects of additives content, sintering temperature and holding time on phase composition, microstructure, dielectric properties and porosity were studied. The porous Si3N4 ceramics were composed of α- Si3N4, SiO2 (cristobalite) and cordierite. Porous Si3N4 ceramics with porosities of 34.12~50.22%, dielectric constant of 2.95~4.45 and dielectric loss of ~0.0025 were obtained.

Preparation and Properties of Porous Si3N4/SiO2/BN Composite Ceramics

2012 ◽  
Vol 512-515 ◽  
pp. 828-831 ◽  
Author(s):  
Wei Dong ◽  
Chang An Wang ◽  
Lei Yu ◽  
Shi Xi Ouyang
Keyword(s):  
Dielectric Constant ◽  
Dielectric Properties ◽  
High Strength ◽  
Low Dielectric Constant ◽  
Pressureless Sintering ◽  
Composite Ceramics ◽  
Porous Si ◽  
Low Dielectric ◽  
Dry Pressing ◽  
Porous Si3n4

Porous Si3N4/SiO2/BN composite ceramics with high strength and low dielectric constant were prepared by dry-pressing process and pressureless sintering at 1750°C for 1.5 h in flow nitrogen. The influences of BN content on microstructure, porosity, mechanical and dielectric properties of the porous Si3N4/SiO2/BN composite ceramics were discussed. The results showed that the porous Si3N4/SiO2/BN composite ceramics with porosity ranging from 29% to 48% were fabricated by adjusting the content of BN. The flexural strength of the porous Si3N4/SiO2/BN composite ceramics was 78215 MPa. The dielectric constant of the porous Si3N4/SiO2/BN composite ceramics was 3.9~5 at 1 MHz.

Effects of Pore Morphology on the Fabrication and Mechanical Properties of Porous Si3N4 Ceramics

2007 ◽  
Vol 280-283 ◽  
pp. 1231-1236
Author(s):  
Jian Feng Yang ◽  
Ji Qiang Gao ◽  
Guo Jun Zhang ◽  
Ichiro Hayashi ◽  
Tatsuki Ohji
Keyword(s):  
Mechanical Properties ◽  
Gas Permeability ◽  
Slip Casting ◽  
Porous Ceramics ◽  
Pore Morphology ◽  
Porous Si ◽  
Die Pressing ◽  
Porous Si3n4 ◽  
Si3n4 Ceramics ◽  
Porous Si3n4 Ceramics

Porous Si3N4 ceramics with different pore morphology have been fabricated, utilizing either organic whiskers or starch as the fugitive agents, through slip-casting and die-pressing technique, respectively. The obtained porous ceramics have rod shaped or equiaxial pore morphology, originated from there two kinds of pore forming agents. The mechanical properties were investigated. The strength decreased considerably when small amount of whiskers were added, however, further increase in the whisker content only cause a moderate decrease of the strength. Gas permeability were measured for the samples with high whisker content of 60 vol% (corresponding to porosity of about 45% in the sintered bodies), and was compared with the counterpart contained the same porosity in which pores were equiaxial. The flexural strength of the samples with these two types of fugitive particles was almost the same, but the permeability of samples with rod-shaped pores were much higher than that with equiaxial pores, which can be understood in terms of a short pass model.

Effect of Y2O3 on the Sintering, Mechanical and Dielectric Properties of Mullite/h-BN Composites

2016 ◽  
Vol 848 ◽  
pp. 28-31
Author(s):  
Han Jin ◽  
Yong Feng Li ◽  
Zhong Qi Shi ◽  
Hong Yan Xia ◽  
Guan Jun Qiao
Keyword(s):  
Fracture Toughness ◽  
Dielectric Constant ◽  
Phase Composition ◽  
High Temperature ◽  
Dielectric Properties ◽  
Liquid Phase ◽  
Flexural Strength ◽  
Sintering Temperature ◽  
Pressureless Sintering ◽  
Different Temperatures

Mullite/10 wt. %h-BN composites with 5 wt. % Y2O3 additive were fabricated by pressureless sintering at different temperatures. The densification, phase composition, microstructure, mechanical and dielectric properties of the mullite/h-BN composites were investigated. With the addition of Y2O3, the sintering temperature of the mullite/h-BN composites declined, while the density, mechanical and dielectric properties all increased. The addition of Y2O3 promoted the formation of liquid phase at high temperature, which accelerated the densification. Besides, Y2O3 particles which were located at the grain boundaries inhibited the grain growth of mullite matrix. For the mullite/h-BN composites with Y2O3 additive, the appropriate sintering temperature was about 1600°C. The relative density, flexural strength, fracture toughness and dielectric constant of the Y2O3 doped mullite/h-BN composite sintered at 1600 °C reached 82%, 135 MPa, 2.3 MPa·m1/2 and 4.9, respectively.

Low-Temperature Firing and Microwave Dielectric Properties of Zn3Nb2O8 Ceramics with CuO-V2O5-Bi2O3

2010 ◽  
Vol 434-435 ◽  
pp. 224-227
Author(s):  
Xu Ping Lin ◽  
Jing Tao Ma ◽  
Bao Qing Zhang ◽  
Ji Zhou
Keyword(s):  
Dielectric Constant ◽  
Phase Composition ◽  
Dielectric Properties ◽  
Relative Density ◽  
Sintering Temperature ◽  
Microwave Dielectric Properties ◽  
Sintering Behavior ◽  
Co Doping ◽  
Microwave Dielectric ◽  
Quality Factor Q

The influence of CuO-V2O5-Bi2O3 addition on the sintering behavior, phase composition, microstructure and microwave dielectric properties of Zn3Nb2O8 ceramics were investigated. The co- doping of CuO, V2O5 and Bi2O3 can significantly lower the sintering temperature of Zn3Nb2O8 ceramics from 1150°C to 900°C. The Zn3Nb2O8-0.5wt% CuO-0.5wt% V2O5-2.0wt% Bi2O3 ceramic sintered at 900°C showed a relative density of 97.1%, a dielectric constant (εr) of 18.2, and a quality factor (Q×f) of 36781 GHz. The dielectric properties in this system exhibited a significant dependence on the relative density, content of additives and sintering temperature. The relative density and dielectric constant (εr) of Zn3Nb2O8 ceramics increased with increasing CuO-V2O5-Bi2O3 additions. And also the relative density and dielectric constant of Zn3Nb2O8 ceramics increased by the augment of the sintering temperature.

Effect of Si3N4 solid contents on mechanical and dielectric properties of porous Si3N4 ceramics through freeze-drying

2018 ◽  
Vol 732 ◽  
pp. 136-140 ◽  
Author(s):  
Ling Li ◽  
Qinggang Li ◽  
Juan Hong ◽  
Mengyong Sun ◽  
Jie Zhang ◽  
...  
Keyword(s):  
Dielectric Properties ◽  
Freeze Drying ◽  
Porous Si3n4 ◽  
Si3n4 Ceramics ◽  
Porous Si3n4 Ceramics

Preparation and Dielectric Properties of Li2O Doped BaZr0.25Ti0.75O3 Ceramics

2011 ◽  
Vol 284-286 ◽  
pp. 1460-1465
Author(s):  
Di Chen ◽  
Xiang Yun Deng ◽  
Jian Bao Li ◽  
Li Ming Wang ◽  
Xin Zheng Wu ◽  
...  
Keyword(s):  
Dielectric Constant ◽  
Dielectric Properties ◽  
Liquid Phase ◽  
Sintering Temperature ◽  
Liquid Phase Sintering ◽  
X Ray Diffraction ◽  
Sintering Aid ◽  
X Ray ◽  
Ceramic Process ◽  
Low Sintering Temperature

BaZr0.25Ti0.75O3(BZT) ceramics were prepared by conventional ceramic process at a relatively low sintering temperature and with an addition of Li2O as the liquid-phase sintering aid. X-ray diffraction characterized results showed that the main crystal phase of the samples with 1.0wt% Li2O additive sintered at 1050°C～1250°C for 4h presented perovskite structure. The dielectric properties of BZT ceramics have been investigated. The dielectric constant of 1.0wt% Li2O doped BZT sintered at 1150°C decreased, and the dielectric loss increased by 0.0012 compared with that of the pure BZT sintered at 1450°C.

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