Non-Oxide Ceramic Nanocomposites with Multifunctionality

2008 ◽  
Vol 403 ◽  
pp. 45-48 ◽  
Author(s):  
Takafumi Kusunose ◽  
Tohru Sekino
Keyword(s):  
Thermal Conductivity ◽  
Electrical Conductivity ◽  
Electric Discharge ◽  
Hot Pressing ◽  
Composite Powder ◽  
High Strength ◽  
The Other ◽  
High Thermal Conductivity ◽  
Oxide Ceramic ◽  
Electric Discharge Machining

Two types of Aluminum nitride (AlN) based ceramic nanocomposite with multifunctionality were investigated to improve machinability or electrical conductivity of AlN ceramics with high thermal conductivity. The AlN/BN nanocomposite was fabricated by hot-pressing AlN-BN composite powder, which was prepared by reducing and heating AlN particles containing a mixture of boric acid, urea and carbon. The nanocomposite containing 20 vol.% BN showed high strength, good machinability and relatively high thermal conductivity. On the other hand, the sintered AlN ceramics with CeO2 as an additive indicated high thermal conductivity and electric conductivity which is possible for electric discharge machining.

Hot-Pressed AlN/BN Composite with Excellent Mechanical and Thermal Properties

2007 ◽  
Vol 544-545 ◽  
pp. 761-764 ◽  
Author(s):  
Takafumi Kusunose ◽  
Myoung Jae Cho ◽  
Tohru Sekino ◽  
Koichi Niihara
Keyword(s):  
Thermal Conductivity ◽  
Thermal Properties ◽  
Boric Acid ◽  
Hot Pressing ◽  
Composite Powder ◽  
High Strength ◽  
High Thermal Conductivity ◽  
Mechanical And Thermal Properties ◽  
Homogeneous Dispersion

In order to give machinability to hard and brittle AlN ceramics, the homogeneous dispersion of fine BN particles into AlN matrix was investigated. The AlN/BN nanocomposite was fabricated by hot-pressing AlN-BN composite powder, which was prepared by reducing and heating AlN particles containing a mixture of boric acid, urea and carbon. The nanocomposite containing 20 vol.% BN showed high strength, machinability and relatively high thermal conductivity.

Utilizing a unified structure model in (3 + 1)-dimensional superspace to identify a homologous phase (Ga1−αAlα)2O3(ZnO) m in ZnO-based thermoelectric composites

2020 ◽  
Vol 53 (6) ◽  
pp. 1542-1549
Author(s):  
Yuichi Michiue ◽  
Hyoung-Won Son ◽  
Takao Mori
Keyword(s):  
Thermal Conductivity ◽  
Electrical Conductivity ◽  
Composite Materials ◽  
The Other ◽  
Structure Model ◽  
X Ray Diffraction ◽  
X Ray ◽  
Long Period ◽  
Profile Fitting ◽  
Doped Zno

A unified structure model in (3 + 1)-dimensional superspace proved suitable for identification of a homologous phase (Ga1−αAlα)2O3(ZnO) m by the profile fitting of powder X-ray diffraction intensities for thermoelectric composite materials in the pseudoternary system ZnO–Al2O3–Ga2O3. A homologous compound of the phase parameter m ≃ 37 was found to coexist with (Al,Ga)-doped ZnO in samples sintered at 1723 K in air. The thermoelectric properties of the composite materials were closely related to the phase fractions. The higher the phase fraction of (Al,Ga)-doped ZnO with the wurtzite structure, the higher the electrical conductivity. On the other hand, the homologous compound with the long-period structure was effective in lowering the thermal conductivity of the materials.

Enhanced through-plane thermal conductivity in Polymer nanocomposites by constructing graphene-supported BN nanotubes

2020 ◽  
Vol 8 (28) ◽  
pp. 9569-9575
Author(s):  
Xu Li ◽  
Ya Li ◽  
Md Mofasserul Alam ◽  
Jibin Miao ◽  
Peng Chen ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Polymer Nanocomposites ◽  
Hot Pressing ◽  
High Thermal Conductivity ◽  
Bn Nanotubes

A graphene-supported BNNT filler is fabricated via the in situ implanting of BNNTs on graphene, with the formation of high thermal conductivity nanocomposites via hot-pressing.

scholarly journals Epsilon-negative BaTiO3/Cu composites with high thermal conductivity and yet low electrical conductivity

2020 ◽  
Vol 6 (1) ◽  
pp. 145-151 ◽  
Author(s):  
Zhongyang Wang ◽  
Kai Sun ◽  
Peitao Xie ◽  
Yao Liu ◽  
Qilin Gu ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Electrical Conductivity ◽  
High Thermal Conductivity

scholarly journals Simultaneous achievement of high thermal conductivity, high strength and formability in Mg-Zn-Ca-Zr sheet alloy

2020 ◽  
Vol 8 (9) ◽  
pp. 335-340 ◽  
Author(s):  
Z. H. Li ◽  
T. T. Sasaki ◽  
T. Shiroyama ◽  
A. Miura ◽  
K. Uchida ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
High Strength ◽  
High Thermal Conductivity ◽  
Sheet Alloy

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 Microstructures and Properties of Cu-rGO Composites Prepared by Microwave Sintering

Materials ◽  
2021 ◽  
Vol 14 (17) ◽  
pp. 4899
Author(s):  
Xuebin Chen ◽  
Lei Zhao ◽  
Liwu Jiang ◽  
Haizhou Wang
Keyword(s):  
Thermal Conductivity ◽  
Electrical Conductivity ◽  
Graphene Oxide ◽  
Ball Milling ◽  
Composite Powder ◽  
Microwave Sintering ◽  
Pure Copper ◽  
Argon Atmosphere ◽  
Copper Particles ◽  
Scanning Electron

This study investigated the effects of microwave sintering on the microstructures and properties of copper-rGO composites. Graphene oxide was coated onto copper particles by wet ball milling, and copper-rGO composites were formed upon microwave sintering in an argon atmosphere. Scanning electron microscopy was then used to observe the mixing in the ball-milled composite powder, and the morphology of the bulk composite after microwave sintering. Raman spectra revealed how graphene oxide changed with ball milling and with microwave sintering. The microhardness, electrical conductivity, and thermal conductivity of the composite were also measured. The results showed that graphene oxide and copper particles were well combined and uniformly distributed after wet ball milling. The overall microhardness of microwave-sintered samples was 81.1 HV, which was 14.2% greater than that of pure copper (71 HV). After microwave sintering, the microhardness of the samples in areas showing copper oxide precipitates with eutectic structures was 89.5 HV, whereas the microhardness of the precipitate-free areas was 70.6 HV. The electrical conductivity of the samples was 87.10 IACS%, and their thermal conductivity was 391.62 W·m−1·K−1.

Graphitic Foam with High Strength and High Thermal Conductivity Doped by Tungsten

2008 ◽  
Vol 27 (4) ◽  
pp. 251-260 ◽  
Author(s):  
Yong Wang ◽  
Lingling Cao ◽  
Jin Gao ◽  
Yimin Wang
Keyword(s):  
Thermal Conductivity ◽  
High Strength ◽  
High Thermal Conductivity ◽  
Graphitic Foam

Fabrication and Microstructure of Electrically Conductive AlN with High Thermal Conductivity

2011 ◽  
Vol 484 ◽  
pp. 57-60
Author(s):  
Takafumi Kusunose ◽  
Tohru Sekino ◽  
Koiichi Niihara
Keyword(s):  
Thermal Conductivity ◽  
Electrical Conductivity ◽  
Rare Earth ◽  
Sintering Temperature ◽  
Rare Earth Oxide ◽  
High Thermal Conductivity ◽  
Boundary Phase ◽  
Sudden Increase ◽  
Electrically Conductive ◽  
Electrical Conductivities

The electrically conductive AlN with high thermal conductivity were successfully fabricated by sintering AlN with a composite additive of 1wt.% Y2O3 and 4wt.% CeO2 in carbon-reduced atmosphere at over 1600 °C. The sudden increase in electrical conductivity is thought to be caused by transition of grain boundary phase from rare-earth oxide to rare-earth oxycarbide. Their electrical conductivities and thermal conductivities increased with increasing sintering temperature. Additionally, sintering temperature influenced the resultant microstructures.

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