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.

Effect of Mineral Composition and Sintering Temperature on the Synthetic Cordierite

2014 ◽  
Vol 633 ◽  
pp. 61-64
Author(s):  
Lei Li ◽  
Rui Long Wen ◽  
Xiao Guang Zhang ◽  
Cheng Biao Wang ◽  
Ming Hao Fang ◽  
...  
Keyword(s):  
Phase Composition ◽  
High Temperature ◽  
Flexural Strength ◽  
Mineral Composition ◽  
Sintering Temperature ◽  
Raw Materials ◽  
Temperature Reaction ◽  
Final Phase ◽  
High Temperature Reaction ◽  
Industrial Alumina

Cordierite samples were prepared using quartz sand tailings, industrial alumina and magnesite tailings as raw materials by high-temperature reaction. The influence of mineral composition and sintering temperature on the final phase composition and physical properties of cordierite were studied. The results shown that a large number of cordierite generated at 1300 °C. When the ratio of Al2O3/SiO2 equals to 1.08, the flexural strength of samples increased to 27.66 MPa.

Effect of Sintering Temperature on Dielectric Properties of CaCu3Ti4O12 Ceramics Prepared by Mechanochemical Process

2014 ◽  
Vol 974 ◽  
pp. 157-161
Author(s):  
Masturah Mohamed ◽  
Mahesh Talari ◽  
Mohd Salleh Mohd Deni ◽  
Azlan Zakaria
Keyword(s):  
Dielectric Constant ◽  
Dielectric Properties ◽  
Sintering Temperature ◽  
Processing Conditions ◽  
Dielectric Measurements ◽  
Frequency Range ◽  
Grain Sizes ◽  
Barrier Capacitance ◽  
Different Temperatures ◽  
Increasing Temperature

CaCu3Ti4O12(CCTO) is well known to have colossal dielectric constant in the range of 105.It is widely accepted that this phenomenon may be attributed to internal layer barrier capacitance (IBLC) model. The dielectric properties of CCTO were reported to be strongly dependent on the processing conditions and grain size. In this work, CCTO samples with different grain sizes were produced by varying sintering temperature in order to investigate IBLC effect on dielectric properties of CCTO. The samples were sintered at four different temperatures, (T=1100°C, 1050°C, 1000°C and 950°C). Dielectric measurements were carried out for the samples in the frequency range of 102– 106Hz using impedance spectrometer. Electron micrographs showed that increasing temperature promoted the grain growth of CCTO while sintering. The internal crystalline defects are seen to play major role by increasing the grain conductivity in dipole formation and increased the dielectric constant of the samples.

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.

scholarly journals Sintering Behaviors, Microstructure, and Microwave Dielectric Properties of CaTiO3–LaAlO3 Ceramics Using CuO/B2O3 Additions

Materials ◽  
2019 ◽  
Vol 12 (24) ◽  
pp. 4187 ◽  
Author(s):  
Min-Hang Weng ◽  
Chihng-Tsung Liauh ◽  
Shueei-Muh Lin ◽  
Hung-Hsiang Wang ◽  
Ru-Yuan Yang
Keyword(s):  
Dielectric Constant ◽  
Dielectric Properties ◽  
Liquid Phase ◽  
Sintering Temperature ◽  
Microwave Dielectric Properties ◽  
Liquid Phase Sintering ◽  
Sintering Aids ◽  
Sintering Aid ◽  
Microwave Dielectric ◽  
Quality Factor Q

The effect of CuO/B2O3 additions on the sintering behaviors, microstructures, and microwave dielectric properties of 0.95LaAlO3–0.05CaTiO3 ceramics is investigated. It is found that the sintering temperatures are lowered efficiently from 1600 °C to 1350 °C, as 1 wt % CuO, 1 wt % B2O3, and 0.5 wt % CuO +0.5 wt % B2O3 are used as the sintering aids due to the appearance of the liquid phase sintering. The microwave dielectric properties of 0.95LaAlO3–0.05CaTiO3 ceramics with the sintering aid additions are strongly related to the densification and the microstructure of the sintered ceramics. At the sintering temperature of 1300 °C, the 0.95LaAlO3–0.05CaTiO3 ceramic with 0.5 wt % CuO + 0.5 wt % B2O3 addition shows the best dielectric properties, including a dielectric constant (εr) of 21, approximate quality factor (Q × f) of 22,500 GHz, and a temperature coefficient of the resonant frequency (τf) of −3 ppm/°C.

Mechanical Properties of SiC/FexSiy Composites

2011 ◽  
Vol 236-238 ◽  
pp. 1523-1527 ◽  
Author(s):  
Xiao Meng Zhang ◽  
Shu Feng Ye ◽  
Li Hua Xu ◽  
Peng Qian ◽  
Lian Qi Wei ◽  
...  
Keyword(s):  
Fracture Toughness ◽  
High Temperature ◽  
Flexural Strength ◽  
Fracture Behavior ◽  
Room Temperature ◽  
Sintering Temperature ◽  
Raw Material ◽  
Reaction Sintering ◽  
Sintering Process ◽  
Scanning Electron

The SiC/FexSiycomposites were synthesized by reaction sintering process with iron tailings as raw material and carbon as reductant. The room and high temperature flexural strengths and fracture toughness of composites were studied in this paper. Fracture surfaces were observed by means of a scanning electron microscope (SEM). The results showed that the room temperature flexural strength of SiC/FexSiycomposites changed along with the different contents of FexSiyand sintering temperature. The flexural strength of composites reaches the maximum at 900°C. The correlation between flexural strength and temperature is consistent with curveⅠ.The fracture toughness of composites is related to the content of FexSiy. The fracture behavior of composites is mainly transcrystalline in room temperature and intercrystalline in high temperature.

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.

High Performance Porous Wave-Transmitting Silicon Nitride Ceramics by Gel-Casting Technique

2012 ◽  
Vol 512-515 ◽  
pp. 869-872 ◽  
Author(s):  
Jian Zhang ◽  
Ji Wei Chen ◽  
Hong Jie Wang
Keyword(s):  
Dielectric Constant ◽  
Dielectric Properties ◽  
Flexural Strength ◽  
High Performance ◽  
Sintering Temperature ◽  
Resonant Cavity ◽  
Porous Ceramics ◽  
Cavity Method ◽  
Pore Former ◽  
Gel Casting

Porous wave transmitting Si3N4 ceramics have been of great interest and technological importance in aerospace area. In this paper, the high performance wave transmitting porous Si3N4 ceramics was prepared by gel-casting method, without any pore-former. The porosity was controlled by the solid content of the slurry and the sintering temperature. The flexural strength and dielectric properties of the material were determined by three bending method and a resonant cavity method. The relationship of the dielectric constant versus the sintering temperature was discussed, and the effect of porosity on dielectric properties was investigated also. As a result, the flexural strength of the porous Si3N4 is 40-200MPa with porosity of 67-45%, dielectric constant of 2.2-3.4 in the frequency of 8GHz at room temperature. With the increase of porosity, both the dielectric constant and dielectric loss decreased. This technique is considered to be a potentially useful method to fabricate the porous ceramics with complex shape.

Pressureless Sintering and Characterization of Al2O3-SiO2-ZrO2 Composite

2012 ◽  
Vol 329 ◽  
pp. 113-128 ◽  
Author(s):  
G. Mebrahitom Asmelash ◽  
Othman Mamat
Keyword(s):  
Fracture Toughness ◽  
Flexural Strength ◽  
Sintering Temperature ◽  
Liquid Phase Sintering ◽  
Pressureless Sintering ◽  
Oxide Ceramic ◽  
Solid Phase Reaction ◽  
Phase Reaction ◽  
X Ray Diffraction ◽  
X Ray

An Oxide Ceramic-Based Composite in the Al2o3-Sio2-Zro2(ASZ) System Was Developed and Investigated Using a Pressureless Sintering Route. the Effect of the Content of each Component and Sintering Temperature upon the Microstructure, Density, Hardness and Strength Was Studied. X-Ray Diffraction (XRD) and Field Emission Scanning Electron Microscopy (FESEM) Were Used to Investigate the Phase Transformation Sequences of the ASZ Composite System. the Flexural Strength Was Measured Using Three-Point Bending Method on a Universal Testing Machine, while the Indentation Fracture (IF) Method Was Used to Determine the Fracture Toughness of the Composite. the Results Showed that, with Varying Zro2Content, Keeping the Silica Content Constant and the Alumina as a Matrix, Densification Tends to Decrease as the Content of Zirconia Increases from 20 Wt. % of the Composition. X-Ray Diffraction Peaks Indicated Fully Developed Alumina, Mullite and Zirconia Phases due to Solid-Phase Reaction and Liquid-Phase Sintering of the System. the Experimental Results Also Revealed that, for a Sintering Temperature of 1500°C, the Hardness Value Ranged from 12 Gpa to 14 Gpa and the Flexural Strength Was 420±31MPa.The Fracture Toughness (KIc) Was Also Reported to Be between 4.5 and 5.1 Mpa.m1/2, for Samples Sintered at a Temperature of 14500C.

Preparation and Mechanical Properties of TiN-Al2O3 Refractory Composites

2013 ◽  
Vol 833 ◽  
pp. 217-220
Author(s):  
Hai Tao Liu ◽  
Ming Hao Fang ◽  
Zhao Hui Huang ◽  
Hai Peng Ji ◽  
Xin Min ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Flexural Strength ◽  
Bulk Density ◽  
Sintering Temperature ◽  
Aluminothermic Reduction ◽  
Pressureless Sintering ◽  
Densification Behaviour ◽  
Effects Of Temperature ◽  
Refractory Composites

TiN-Al2O3 bulk composites were prepared by pressureless sintering of the as-synthesized powder products obtained by aluminothermic reduction-nitridation of aluminum dross and rutile. The effects of temperature on the densification behaviour and mechanical properties of TiN-Al2O3 composites were studied. Results showed that the bulk density of the TiN-Al2O3 composites increased with the elevated sintering temperature. When the temperature arrived at 1500 °C, the flexural strength and fracture toughness reached the highest values (201.48 MPa and 4.11 MPa·m1/2, respectively).

Sintering and Dielectric Properties of SrTiO3-based Ceramics

2012 ◽  
Vol 1397 ◽  
Author(s):  
Juan Li ◽  
Dengren Jin ◽  
Lixin Zhou ◽  
Jinrong Cheng
Keyword(s):  
Dielectric Constant ◽  
Dielectric Properties ◽  
Room Temperature ◽  
Sintering Temperature ◽  
Precursor Solution ◽  
Particle Sizes ◽  
Low Dielectric ◽  
Different Temperatures ◽  
High Dielectric ◽  
Room Temperature Dielectric Constant

ABSTRACTHigh dielectric tunability, low dielectric loss tangent and appropriate level of dielectric constant are the basic requirements for applications as electrically tunable dielectric microwave devices. In our experiments, the SrTiO3 green compacts made of the powder mixtures with various particle sizes were infiltrated with a BaTiO3 precursor solution and sintered at different temperatures between 1280 and 1350 ºC for 2 hours and 1350 ºC for 6 hours. The sintering, microstructural and dielectric properties were investigated. Results showed that the relative density of SrTiO3 ceramics could reached 93% when sintered at 1280 ºC for 2 hours. When sintered for 6 hours at 1350 °C, the room temperature dielectric constant of SrTiO3 reaches 900 at a frequency of 1MHz. It has only weak temperature dependence between 100 and 500K. The reason of the low sintering temperature for the dense SrTiO3 ceramics and the effects of sintering scheme on the dielectric properties from 100 K to 500 K are discussed in this paper.

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