scholarly journals Effect of Silicon Nitride (Si3N4) on Mechanical and Dielectric Properties of Fused Silica Ceramic Composites

2021 ◽  
Author(s):  
Pagidi Madhukar ◽  
Kishore Kumar Kandi ◽  
Gurabvaiah Punugupati ◽  
C.S.P. Rao
Keyword(s):  
Dielectric Constant ◽  
Dielectric Properties ◽  
Flexural Strength ◽  
Ceramic Composites ◽  
Fused Silica ◽  
Solid Loading ◽  
Monomer Ratio ◽  
Monomer Content ◽  
Gelcasting Process ◽  
Silica Ceramic

Abstract Fused silica ceramics composites were widely using for the fabrication of radomes which is the vital component of a missile. The required properties were attained by the addition of small amounts of Silicon Nitride (Si3N4) to the fused silica for enhancing flexural strength and without disturbing the dielectric properties. In the present work, porous fused silica ceramic composites were fabricated using gelcasting process, a near net shaping technique. The experiments were conducted using Response Surface Methodology (RSM) central composite with face centered design with six centre points approach. The process parameters of gelcasting process such as solid loading, monomer ratio, monomer content and additive (Si3N4) were considered as input parameters and flexural strength, porosity and dielectric constant as response parameters. Single parameter and interaction parameter effect on responses were studied. The effectiveness of derived models was compared with Analysis of Variance (ANOVA) at 95% confidence level. Statistical analysis proven that input parameters have critical effect on responses. The derived RSM mathematical models have a higher R2 values (Flexural strength 97.62%, Porosity 95.12% and dielectric constant 95.93%) which shows the critical relation between actual and predicted values. The optimal responses obtained were flexural strength 86.173 MPa, porosity 39.767% and dielectric constant 6.949 corresponding parameters process parameters solid loading 47.95%, additive (Si3N4) 10.43 wt%, monomer content 15 wt% and monomer ratio 3.

Influence of Silicon Nitride (Si3N4) on Mechanical and Dielectric Properties of a Novel Fused Silica Ceramic Composites

Silicon ◽  
2021 ◽  
Author(s):  
Kishore Kumar Kandi ◽  
Gurabvaiah Punugupati ◽  
Pagidi Madhukar ◽  
C. S. P. Rao ◽  
Murthy Chavali
Keyword(s):  
Dielectric Properties ◽  
Silicon Nitride ◽  
Ceramic Composites ◽  
Fused Silica ◽  
Silica Ceramic

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.

Dielectric Properties of Sol - Gel Silica Glasses

1986 ◽  
Vol 72 ◽  
Author(s):  
G. V. Chandrashekhar ◽  
M. W. Shafer
Keyword(s):  
Dielectric Constant ◽  
Dielectric Properties ◽  
Elemental Carbon ◽  
Sol Gel ◽  
Fused Silica ◽  
Dielectric Constants ◽  
Low Dielectric Constant ◽  
Silica Glasses ◽  
Low Dielectric ◽  
Gel Technique

AbstractDielectric properties have been measured for a series of porous and fully densified silica glasses, prepared by the sol-gel technique starting from Si-methoxide or Si-fume. The results for the partially densified glasses do not show any preferred orientation for porosity. When fully densified (˜2.25 gms/cc) without any prior treatment of the gels, they have dielectric constants of ≥ 6.5 and loss factors of 0.002 at 1 MHz, compared to values of 3.8 and <0.001 for commercial fused silica. There is no corresponding anomaly in the d.c. resistivity. Elemental carbon present to the extent of 400–500 ppm is likely to be the main cause for this enhanced dielectric constant. Extensive cleaning of the gels prior to densification to remove this carbon were not completely successful pointing to the difficulty in preparing high purity, low dielectric constant glasses via the organic sol-gel route at least in the bulk form.

Erosion Behavior of Gelcast Fused Silica Ceramic Composites

Silicon ◽  
2019 ◽  
Vol 12 (4) ◽  
pp. 903-911
Author(s):  
Gurabvaiah Punugupati ◽  
P. S. C. Bose ◽  
G. Raghavendra ◽  
C. S. P. Rao ◽  
S. Ojha
Keyword(s):  
Ceramic Composites ◽  
Fused Silica ◽  
Erosion Behavior ◽  
Silica Ceramic

Effect of the Annealing Temperature on Dielectric Properties of Bi1.5Zn1.0Nb1.5O7 Films Prepared by MOCVD

2008 ◽  
Vol 388 ◽  
pp. 175-178
Author(s):  
Hiroshi Funakubo ◽  
Shingo Okaura ◽  
Muneyasu Suzuki ◽  
Hiroshi Uchida ◽  
Seiichiro Koda
Keyword(s):  
Dielectric Constant ◽  
Dielectric Properties ◽  
Dielectric Loss ◽  
Temperature Coefficient ◽  
Annealing Temperature ◽  
Relative Dielectric Constant ◽  
Fused Silica ◽  
The Other ◽  
Other Hand ◽  
Silica Substrates

Effect of annealing temperature on the dielectric properties of Bi1.5Zn1.0Nb1.5O7 films prepared on (111)Pt//(001)Al2O3 and (111)Pt/fused silica substrates by MOCVD was investigated. The tunability and the inverse of the dielectric loss [1/ (tan )] increased with increasing annealing temperature. Relative dielectric constant and temperature coefficient of the capacitance (TCC) increased with the crystallinity of the films. On the other hand, (1/tan ) was independent of the crystallinity of the films, but was dramatically increased by the annealing.

scholarly journals Investigations on Structural, Mechanical, and Dielectric Properties of PVDF/Ceramic Composites

2015 ◽  
Vol 2015 ◽  
pp. 1-9 ◽  
Author(s):  
Anshuman Srivastava ◽  
Karun Kumar Jana ◽  
Pralay Maiti ◽  
Devendra Kumar ◽  
Om Parkash
Keyword(s):  
Dielectric Constant ◽  
Dielectric Properties ◽  
Single Phase ◽  
Extrusion Process ◽  
Ceramic Composites ◽  
X Ray Diffraction ◽  
Composite State ◽  
X Ray ◽  
Embedded Capacitor ◽  
Xrd Patterns

Polymer ceramic composites are widely used for embedded capacitor application. In the present work PVDF has been used as a matrix and CCTO and LaCCTO have been used as reinforcement. Extrusion process has been used for the synthesis of composites. X-ray diffraction (XRD) patterns confirm the formation of single phase CCTO, and LaCCTO in its pure as well as composite state. It is found that La doping in CCTO considerably increases the dielectric constant and reduces the dielectric loss. A similar trend is observed in the composites with the increasing content of CCTO and LaCCTO.

Novel magnetodielectric cobalt ferrite–titania–silica ceramic composites with tunable dielectric properties

2016 ◽  
Vol 42 (15) ◽  
pp. 16650-16654
Author(s):  
Pietro Galizia ◽  
Davide Gardini ◽  
Simona Ortelli ◽  
Claudio Capiani ◽  
Maksimas Anbinderis ◽  
...  
Keyword(s):  
Dielectric Properties ◽  
Cobalt Ferrite ◽  
Ceramic Composites ◽  
Silica Ceramic

Research on Rheological Behavior of Si3N4-SiC Composites by Gelcasting

2014 ◽  
Vol 1004-1005 ◽  
pp. 488-491 ◽  
Author(s):  
Xiao Ran Gong ◽  
Shuang Sheng Shen ◽  
Jin Wu
Keyword(s):  
Flexural Strength ◽  
Bulk Density ◽  
Rheological Behavior ◽  
Volume Fraction ◽  
Raw Material ◽  
Solid Loading ◽  
Uniform Structure ◽  
Sic Particles ◽  
Sic Composites ◽  
Gelcasting Process

Using SiC particles and powder, the modified Si and α-Si3N4powder as the main raw material, Si3N4-SiC composite materials have been fabricated by gelcasting. The Si3N4-SiC suspension with 75vol% (volume fraction) solid loading exhibits shear thinning rheological behavior under a shear rate from 10 to 160s-1, which meets the requirement of the gelcasting process. The bulk density of the green bodies after solidification is 2.57 g·cm-3and the flexural strength 16 MPa, the green bodies have a dense and uniform structure. The bulk density and flexural strength of the Si3N4-SiC composites after nitriding are 2.67g·cm-3and 48 MPa respectively; the strength is higher than that of other industrial products without gelcasting. Well-developed intertwined fibrous Si3N4crystals grow on the surface of the SiC particles to form a tight microstructure in the Si3N4-SiC composites after firing.

scholarly journals Influence of Al2O3 content on mechanical properties of silica-based ceramic cores prepared by stereolithography

2021 ◽  
Author(s):  
Wen Zheng ◽  
Jia-Min Wu ◽  
Shuang Chen ◽  
Chang-Shun Wang ◽  
Chun-Lei Liu ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
Flexural Strength ◽  
Room Temperature ◽  
Linear Shrinkage ◽  
Fused Silica ◽  
Al2o3 Content ◽  
High Temperature Mechanical Properties ◽  
Silica Ceramic ◽  
Excellent Chemical

AbstractSilica ceramic cores have played an important part in the manufacture of hollow blades due to their excellent chemical stability and moderate high-temperature mechanical properties. In this study, silica-based ceramics were prepared with Al2O3 addition by stereolithography, and the influence of Al2O3 content on mechanical properties of the silica-based ceramics was investigated. The Al2O3 in silica-based ceramics can improve the mechanical properties by playing a role as a seed for the crystallization of fused silica into cristobalite. As a result, with the increase of Al2O3 content, the linear shrinkage of the silica-based ceramics first decreased and then increased, while the room-temperature flexural strength and the high-temperature flexural strength first increased and then decreased. As the Al2O3 content increased to 1.0 vol%, the linear shrinkage was reduced to 1.64% because of the blocked viscous flow caused by Al2O3. Meanwhile, the room-temperature flexural strength and the high-temperature flexural strength were improved to 20.38 and 21.43 MPa with 1.0 vol% Al2O3, respectively, due to the increased α-cristobalite and β-cristobalite content. Therefore, using the optimal content of Al2O3 in silica-based ceramics can provide excellent mechanical properties, which are suitable for the application of ceramic cores in the manufacturing of hollow blades.

scholarly journals Surface-modified Zn0.5Ti0.5NbO4 particles filled polytetrafluoroethylene composite with extremely low dielectric loss and stable temperature dependence

2020 ◽  
Vol 9 (6) ◽  
pp. 726-738
Author(s):  
Hao Wang ◽  
Fuming Zhou ◽  
Jianming Guo ◽  
Yuanyuan Zhang ◽  
Hui Yang ◽  
...  
Keyword(s):  
Dielectric Constant ◽  
Dielectric Properties ◽  
Dielectric Loss ◽  
Photoelectron Spectroscopy ◽  
Ceramic Composites ◽  
Surface Characteristic ◽  
Low Dielectric ◽  
Stable Temperature ◽  
Ptfe Composites ◽  
Microwave Substrate

AbstractPolymer-ceramic composites are widely applied in microwave substrate materials due to the excellent dielectric properties and simple preparation process recently. Polytetrafluoroethylene-based (PTFE) composites filled with Zn0.5Ti0.5NbO4 (ZTN) ceramic particles were fabricated by hot-pressing. The particles were modified by C14H19F13O3Si to enhance the interface compatibility between PTFE and ZTN powders, which was characterized by X-ray photoelectron spectroscopy (XPS) and contact angle. The surface characteristic of particles transformed into hydrophobicity and tight microstructure as well as better dielectric properties were obtained after the surface modification. The microstructure, dielectric, thermal, mechanical properties, and water absorption of the composites concerning ZTN content were investigated. Modified ZTN/PTFE composites with 50 vol% ZTN particles exhibit excellent dielectric properties with a high dielectric constant of 8.3, an extremely low dielectric loss of 0.00055 at 7 GHz, and a stable temperature coefficient of the dielectric constant of −12.2 ppm/°C. All the properties show modified ZTN particles filled PTFE composite is the potential material for microwave substrate application.

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