Effect of thermal annealing on dielectric property and thermal conductivity of Si3N4–BaTiO3 composite ceramics

2021 ◽  
Author(s):  
Chunyan Zhang ◽  
Hongwei Wang ◽  
Haolan Fang ◽  
Fancheng Meng ◽  
Huixing Lin
Keyword(s):  
Thermal Conductivity ◽  
Dielectric Property ◽  
Thermal Annealing ◽  
Composite Ceramics

Hot-pressing sintered BN-SiO2 composite ceramics with excellent thermal conductivity and dielectric properties for high frequency substrate

2018 ◽  
Vol 44 (14) ◽  
pp. 16594-16598 ◽  
Author(s):  
Liangliang Wu ◽  
Feng Xiang ◽  
Wenlong Liu ◽  
Rong Ma ◽  
Hong Wang
Keyword(s):  
Thermal Conductivity ◽  
Dielectric Properties ◽  
Hot Pressing ◽  
High Frequency ◽  
Composite Ceramics

Fabrication and Properties of Porous Anorthite⁄Mullite Ceramics

2012 ◽  
Vol 512-515 ◽  
pp. 590-595 ◽  
Author(s):  
Ya Mei Lin ◽  
Cui Wei Li ◽  
Feng Kun Yang ◽  
Chang An Wang
Keyword(s):  
Thermal Conductivity ◽  
Compressive Strength ◽  
Open Porosity ◽  
Raw Material ◽  
Composite Ceramics ◽  
Porous Composite ◽  
Mullite Phase ◽  
Powder Content ◽  
Mullite Powder ◽  
Mullite Ceramics

Porous anorthite/mullite composite ceramics with different mullite content were fabricated by foam-gelcasting, using CaCO3, SiO2, α-Al2O3as raw material for anorthite phase and mullite powder for mullite phase. Effects of mullite powder content on bulk density, porosity, compressive strength and thermal conductivity of the porous composite ceramics were researched. It has been shown that mullite powder content has great effect on microstructure and properties of the porous anorthite⁄mullite composite ceramics. The open porosity of the prepared porous anorthite⁄mullite composite ceramics is in the range of 58.7 %~77.5 %, the compressive strength is between 4.2 and 30.9 MPa, and the thermal conductivity is in the range of 0.18 ~1.47 W⁄(m·K).

Microstructure and Properties of Spark Plasma Sintering AlN/BN Ceramics

2006 ◽  
Vol 313 ◽  
pp. 105-108 ◽  
Author(s):  
Lian Meng Zhang ◽  
Mei Juan Li ◽  
Qiang Shen ◽  
T. Li ◽  
M.Q. Yu
Keyword(s):  
Mechanical Properties ◽  
Thermal Conductivity ◽  
Mechanical Strength ◽  
Spark Plasma Sintering ◽  
Volume Fraction ◽  
Sintering Temperature ◽  
Composite Ceramics ◽  
Plasma Sintering ◽  
Spark Plasma ◽  
Full Densification

Aluminum nitride-boron nitride (AlN/BN) composite ceramics were prepared by spark plasma sintering (SPS). The sintering behaviors of AlN/BN composites with 5~15% volume fraction of BN were studied. The influences of BN content, as well as the sintering temperature on the density, microstructure, mechanical strength, thermal conductivity and machinability of the composites were also investigated. The results showed that the full densification of AlN/BN composite ceramics could be realized by SPS technique at the temperature no higher than 1800°C for 3 minutes. The thermal conductivity of AlN/BN composites is in the range of 66~79W/mK, and AlN/BN composites can be cut or drilled by carbides or even steel tools when BN content is 15% volume fraction. The mechanical strength of AlN/BN composites is about 330MPa and is not remarkably affected by the addition of BN. The improvement of mechanical properties of AlN/BN composite ceramics is due to the fine and homogenous microstructure developed in the SPS process.

Thermal Annealing Effect on the Thermal and Electrical Properties of Organic Semiconductor Thin Films

MRS Advances ◽  
2016 ◽  
Vol 1 (22) ◽  
pp. 1637-1643 ◽  
Author(s):  
Xinyu Wang ◽  
Boyu Peng ◽  
Paddy Chan
Keyword(s):  
Thermal Conductivity ◽  
Electrical Properties ◽  
Thermal Annealing ◽  
Organic Semiconductor ◽  
Field Effect ◽  
Annealing Temperature ◽  
Waste Heat ◽  
Annealing Effect ◽  
Field Effect Mobility ◽  
Thermal And Electrical Properties

ABSTRACTThe thermal and electrical properties of organic semiconductor are playing critical roles in the device applications especially on the devices with large area. Although the effect may be minor in a single device like field effect transistors, the unwanted waste heat would cause much more severe problems in large-scale devices as the power density will go up significantly. The waste heat would lead to performance degradation or even failure of the devices, and thus a more detailed study on the thermal conductivity and carrier mobility of the organic thin film would be beneficial to predict the limits of the device or design a thermally stable device. Here we explore the thermal annealing effect on the thermal and electrical properties of the small molecule organic semiconductor, dinaphtho[2,3-b:2’,3’-f]thieno[3,2-b]thiophene (DNTT). After the post deposition thermal annealing, the grain size of the film increases and in-plane crystallinity improves while cross-plane crystallinity keeps relatively constant. We demonstrated the cross-plane thermal conductivity is independent of the thermal annealing temperature and high annealing temperature will reduce the space-charge-limited current (SCLC) mobility. When the annealing temperature increase from 24 °C to 140 °C, the field effect mobility shows a gradual increase while the threshold voltage shifts from positive to negative. The different dependence of the SCLC mobility and field effect mobility on the annealing temperature suggest the improvement of the film crystallinity after thermal annealing is not the only dominating effect. Our investigation provides the constructive information to tune the thermal and electrical properties of organic semiconductors.

Cross-Property Relations between Elastic and Thermal Properties of Porous Ceramics

2006 ◽  
Vol 45 ◽  
pp. 107-112 ◽  
Author(s):  
W. Pabst ◽  
Eva Gregorová
Keyword(s):  
Thermal Conductivity ◽  
Elastic Moduli ◽  
Porous Alumina ◽  
Tensile Modulus ◽  
Porous Ceramics ◽  
The Other ◽  
Composite Ceramics ◽  
Shear Moduli ◽  
Property Relations ◽  
The One

The cross-property relations between the elastic moduli and the thermal conductivity of porous ceramics are reviewed from the viewpoint of micromechanics (composite theory). Consequences of the rigorous Milton-Torquato and Gibiansky-Torquato relations (in the form of bounds, i.e. inequalities derived between bulk or shear moduli on the one hand and thermal conductivity on the other) are compared to various approximate relations (equalities) recently proposed between the tensile modulus (Young’s modulus) and thermal conductivity, among them the two new cross-property relations proposed by the authors. The relations are critically discussed and applied to the case of porous alumina, zirconia and alumina-zirconia composite ceramics.

scholarly journals Improvement in mechanical properties in AlN-h-BN composites with high thermal conductivity

2021 ◽  
Author(s):  
Zetan Liu ◽  
Shiqiang Zhao ◽  
Tian Yang ◽  
Ji Zhou
Keyword(s):  
Mechanical Properties ◽  
Thermal Conductivity ◽  
Hexagonal Boron Nitride ◽  
Relative Dielectric Constant ◽  
High Strength ◽  
Secondary Phase ◽  
High Thermal Conductivity ◽  
Raw Material ◽  
Composite Ceramics ◽  
Powder Particles

AbstractIt is possible to improve the machinability of aluminum nitride-hexagonal boron nitride (AlN-h-BN) ceramics while maintaining high strength and high thermal conductivity. The composite ceramics with 0–30 wt% BN as secondary phase were prepared by hot pressed sintering, using yttrium oxide (Y2O3) as sintering aid. The phase composition, density, microstructure, mechanical properties, thermal conductivity, and dielectric properties were investigated. The sintering additives were favorable to purify the grain boundaries and improve densification, reacting with oxide impurities on the surface of raw material powder particles. The optimum BN content improved the flexural strength and fracture toughness of composite ceramics with 475 MPa and 4.86 MPa·m1/2, respectively. With increasing the amount of BN, the thermal conductivity and hardness of composites gradually decreased, but the minimum value of thermal conductivity was still 85.6 W·m−1·K−1. The relative dielectric constant and dielectric loss tangent of the samples ranged from 6.8 to 8.3 and from 2.4 × 10−3 to 6.4 × 10−3, respectively, in 22–26 GHz.

scholarly journals High-thermally conductive AlN-based microwave attenuating composite ceramics with spherical graphite as attenuating agent

2020 ◽  
Author(s):  
Xia Fang ◽  
Lei Jiang ◽  
Limei Pan ◽  
Shuang Yin ◽  
Tai Qiu ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Three Dimensional ◽  
High Thermal Conductivity ◽  
Composite Ceramics ◽  
Dielectric Constant And Loss ◽  
Spherical Graphite ◽  
Thermally Conductive ◽  
Absorption Performance ◽  
Hot Pressing Sintering ◽  
Addition Amount

Abstract High-thermally conductive AlN-based microwave attenuating composite ceramics with spherical graphite (SG) as the attenuating agent were fabricated through hot-pressing sintering. The SG maintains its three-dimensional morphology within the sintered bodies, which considerably impedes the sintering of the composites to some extent but slightly influences on the growth of AlN grains. The addition of SG reduces the strength of the composites, but provides a moderate toughening effect at the optimal addition amount (3.8 MPa·m1/2 at 4 wt% SG). Benefiting from the low anisotropy, high thermal conductivity, and the three-dimensional morphology of SG, the composites exhibit a relatively higher thermal conductivity (76.82 W·m-1·k-1 at 10 wt% SG) compared with composites added with non-spherical attenuating agent. The dielectric constant and loss (8.2–12.4 GHz) increase remarkably as the amount of SG added increases up to 8 wt%, revealing that the incorporation of SG improves the dielectric property of the composite. The composite with 7 wt% SG exhibits the best absorption performance with a minimum reflection loss of -14 dB at 12.4 GHz and an effective absorbing bandwidth of 0.87 GHz. The excellent overall properties of the SG/AlN microwave attenuating composites render them as a promising material for various applications. Moreover, SG has a great potential as an attenuating agent for microwave attenuating composites due to its strong attenuation upon integration, high thermal conductivity, and low anisotropy.

Fabrication of PMIA/fBN Dielectric Composite with Enhanced Breakdown Strength and Thermal Conductivity

2019 ◽  
Vol 960 ◽  
pp. 256-262
Author(s):  
Guang Yu Duan ◽  
Zu Ming Hu
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
High Temperature ◽  
Dielectric Property ◽  
Dielectric Loss ◽  
Breakdown Strength ◽  
Dielectric Composite ◽  
Novel Method ◽  
Thermal Conductivities

A high-temperature poly (m-phenyleneisophthalamide) (PMIA) dielectric composite was successfully manufactured with functionalized BN (fBN) fillers. Due to effective modification by KH-550, fBN particles evenly dispersed in PMIA matrix. The dielectric property, breakdown strength and thermal conductivity of PMIA/fBN dielectric composite were researched. The consequences indicate that fBN fillers can not only decrease the dielectric loss but also enhance the breakdown strength of PMIA/fBN dielectric composites. Furthermore, owing to the generated heat transfer pathways by fBN particles, the thermal conductivities improved from 0.23 W·m-1·K-1 of fBN-0 to 0.86 W·m-1·K-1 of fBN-30, demonstrating a significant improvement. These results present a novel method for fabricating high-temperature PMIA/fBN dielectric composites with improved breakdown strength and thermal conductivity.

Preparation of ASZ Thermal Storage Ceramics for Solar Thermal Power Generation

2013 ◽  
Vol 320 ◽  
pp. 44-51
Author(s):  
Jian Feng Wu ◽  
Bin Zheng Fang ◽  
Xiao Hong Xu ◽  
Peng Li ◽  
Xin Bin Lao ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Power Generation ◽  
Silicon Carbide ◽  
Thermal Shock ◽  
Thermal Power ◽  
Solar Thermal ◽  
Composite Ceramics ◽  
Solar Thermal Power ◽  
Thermal Power Generation ◽  
Solar Thermal Power Generation

This paper aims to investigate the properties and microstructure of Al2O3-SiC-ZrO2(ASZ) composite ceramics for solar thermal power generation. The composite ceramics were prepared from α-Al2O3, partially stabilized zirconia (Y2O35.2 wt%) and silicon carbide fired at 1280 °C for 2 h through pressureless sintering. Influence of the contents of SiC and ZrO2on the performance of ASZ composite ceramics have been observed and extensively investigated via XRD, SEM, etc. The results revealed that the thermal shock resistance and high-temperature thermal properties would increase with the increase of the SiC content. No cracking occurred after 30 times thermal shock (from room temperature to 800°C with air cooling) while the bending strength after thermal shock test, the thermal expansion coefficient, the heat capacity, the thermal conductivity coefficient and the thermal conductivity were 76.99MPa (with a growth rate of 27.89% after thermal shock), 5.85×10-6°C-1, 1.05 kJ(kgK)-1, 0.01 cm2s-1, 2.26 W(mK)-1, respectively. The XRD patterns indicated that the main crystal phases included corundum, silicon carbide and zirconium silicate while the SEM images illustrated the well-grown crystal grains had the sizes distributed among 5-120 μm.Key words: Al2O3-SiC-ZrO2composite ceramics, Silicon carbide, Thermal properties,Microstructure, Solar thermal power generation

Effect of γ-PVDF on enhanced thermal conductivity and dielectric property of Fe-rGO incorporated PVDF based flexible nanocomposite film for efficient thermal management and energy storage applications

RSC Advances ◽  
2016 ◽  
Vol 6 (44) ◽  
pp. 37773-37783 ◽  
Author(s):  
Sumanta Kumar Karan ◽  
Amit Kumar Das ◽  
Ranadip Bera ◽  
Sarbaranjan Paria ◽  
Anirban Maitra ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Energy Storage ◽  
Dielectric Property ◽  
Energy Density ◽  
Crystallite Size ◽  
Thermal Management ◽  
Nanocomposite Film ◽  
Energy Storage Applications ◽  
Enhanced Thermal Conductivity

Dependence of thermal conductivity and energy density on the amount of crystalline γ-phase and γ-crystallite size of PVDF in Fe-rGO/PVDF nanocomposites has been explored.

Sign in / Sign up

Export Citation Format

Share Document