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

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.

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High Strength and High Thermal Conductivity Carbon Foam Reinforced with Graphite Nanoparticles

Cellular Polymers ◽

10.1177/026248930702600502 ◽

2007 ◽

Vol 26 (5) ◽

pp. 305-312 ◽

Cited By ~ 2

Author(s):

Yong Wang ◽

Zhi Xu ◽

Qingqing An ◽

Yimin Wang

Keyword(s):

Mechanical Properties ◽

Thermal Conductivity ◽

High Pressure ◽

Coal Tar ◽

High Strength ◽

Carbon Foam ◽

High Thermal Conductivity ◽

Mesophase Pitch ◽

High Pressure And Temperature ◽

Graphite Nanoparticles

A novel carbon foam with high strength and high thermal conductivity was prepared through the incorporation of graphite nanoparticles into coal tar based mesophase pitch precursor. Carbon foam was obtained after carbonization and graphitication of pitch foam formed by the pyrolysis of coal tar based mesophase pitch mixed with graphite nanoparticles in a high pressure and temperature chamber. The foam had possessed high strength and exceptional high thermal conductivity. SEM observation showed that less micro cracking appeared on the cell wall of foam by the addition of graphite nanoparticles. The test of thermal conductivity and mechanical properties shows that the thermal conductivity of modified carbon foam could reach 195 W/m.K. The mechanical properties were improved markedly, and compressive strength was increased from 2 MPa to 18.8 MPa when the additive amount of graphite nanoparticles was 8%.

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Effect of Additives on Thermal Conductivity of Si3N4 Ceramics

Materials Science Forum ◽

10.4028/www.scientific.net/msf.1036.185 ◽

2021 ◽

Vol 1036 ◽

pp. 185-195

Author(s):

Zi Hao Chen ◽

Qiang Gu ◽

Wei Kui Ma ◽

Guo Qi Liu

Keyword(s):

Thermal Conductivity ◽

High Speed ◽

Heat Dissipation ◽

High Strength ◽

High Thermal Conductivity ◽

Raw Material ◽

Β Phase ◽

Sealing Material ◽

Strong Current ◽

High Oxidation Resistance

Compared with traditional ceramics, Si3N4 ceramics have the characteristics of high theoretical thermal conductivity, high thermal shock resistance, high oxidation resistance, high strength, and strong current carrying capacity. It is a potential high-speed circuit and high-power device for heat dissipation and heat dissipation. Sealing material. For applications in 5these fields, β-Si3N4 with a relatively stable structure and high thermal conductivity is an ideal material. However, β-Si3N4 powder is difficult to sinter as a raw material. Therefore, the prepared Si3N4 generally has a low density, and there are various defects in the crystal. The existence of these defects will cause interference and scattering of heat in the transfer process. Limits the application of β-Si3N4 ceramics. Studies have shown that the introduction of different additives can form a liquid phase at high temperatures, which can effectively reduce the firing temperature of the sample and increase the density. At the same time, it can also remove lattice oxygen, weaken the intercrystalline phase, and promote the α→β phase transition. Thereby improving the thermal conductivity and sintering performance of Si3N4 ceramics. Therefore, this article reviews the types of additives and their effects on the properties of Si3N4 ceramics and their mechanism. Trying to find an additive system for the preparation of high thermal conductivity Si3N4 ceramics with excellent comprehensive performance, hoping to provide help for the work and researchers engaged in the research on the thermal conductivity of Si3N4 ceramics.

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Highly Thermoconductive Yet Ultraflexible Polymer Composite with Superior Mechanical Properties and Autonomous Self-Healing Functionality via Binary Fillers Strategy

Materials Horizons ◽

10.1039/d1mh01746b ◽

2022 ◽

Author(s):

Dong Wang ◽

Dingyao Liu ◽

JianHua Xu ◽

JiaJun Fu ◽

Kai Wu

Keyword(s):

Mechanical Properties ◽

Thermal Conductivity ◽

Polymer Composite ◽

High Thermal Conductivity ◽

Thermal Dissipation ◽

Self Healing ◽

Formidable Challenge ◽

Superior Mechanical Properties

It is still a formidable challenge to develop ideal thermal dissipation materials with simultaneous high thermal conductivity, excellent mechanical softness and toughness, and spontaneous self-healing. Herein, we report the introduction...

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Thermal Conductivity of Si₃N₄ Ceramics Fabricated From Carbothermal-reduction-derived Powder

10.21203/rs.3.rs-910628/v1 ◽

2021 ◽

Author(s):

Yuelong Wang ◽

Xingyu Li ◽

Haoyang Wu ◽

Baorui Jia ◽

Deyin Zhang ◽

...

Keyword(s):

Mechanical Properties ◽

Thermal Conductivity ◽

Fracture Toughness ◽

Grain Size ◽

Flexural Strength ◽

Grain Boundaries ◽

Carbothermal Reduction ◽

Secondary Phase ◽

Gas Pressure ◽

Gas Pressure Sintering

Abstract Si3N4-based ceramic (Si3N4-5wt%Y2O3-3wt%MgO) was obtained from carbothermal-reduction-derived powder combined with gas pressure sintering. The phase, microstructure, thermal conductivity and mechanical properties of Si3N4 ceramics were comprehensively analyzed. Dense Si3N4 ceramic with uniform grain size was obtained after sintering at 1900°C for 7 h under a N2 pressure of 1.2 MPa. The secondary phase consisted of Y4Si2O7N2 and Y2Si3O3N4 was found to gather around triangular grain boundaries. The thermal conductivity, flexural strength, hardness and fracture toughness of the Si3N4 ceramics were 95.7 W·m-1·k-1, 715 MPa, 17.2 GPa and 7.2 MPa·m1/2, respectively. The results were compared with product derived from commercial powder, the improvement of thermal conductivity (~8.3%) and fracture toughness (~4.3%) demonstrating the superiority of Si3N4 ceramics prepared from carbothermal-reduction-derived powder.

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Research on the Densification Process of the Mechanically-Alloyed Amorphous 2Si-B-3C-N Powder

Solid State Phenomena ◽

10.4028/www.scientific.net/ssp.281.15 ◽

2018 ◽

Vol 281 ◽

pp. 15-21

Author(s):

Peng Fei Zhang ◽

De Chang Jia ◽

Bin Yang ◽

Guang Xin Wang

Keyword(s):

Mechanical Properties ◽

Hexagonal Boron Nitride ◽

Amorphous Powder ◽

Silicon Powder ◽

Graphite Powder ◽

Densification Process ◽

Mechanically Alloyed ◽

Powder Particles ◽

Average Size ◽

N Powder

A mixture of the commercially available cubic silicon powder, hexagonal boron nitride powder and graphite powder was mechanically alloyed to prepare amorphous 2Si-B-3C-N composite powder. The amorphous powder was heated up to 1900°C in nitrogen, with a heating rate of 20°C/min and under a pressure of 80 MPa. Careful investigation was carried out on the densification curve, the microstructure and the mechanical properties of the prepared ceramics. Results show that the amorphous 2Si-B-3C-N powder mainly consists of near-spherical agglomerates, with an average size of 3.5±2.4 micrometers. When the amorphous powder was hot pressed, the densification process mainly included three stages, the denser packing of powder particles with the help of axial pressure, the initial sintering at about 1500-1800°C, and the rapid sintering at temperatures approximately higher than 1830°C. When the 2Si-B-3C-N ceramic was hot pressed at 1900°C for 10-30 mins, it exhibited large volume shrinkage, noticeable reduction of pores, and significantly improvement of density and mechanical properties. The applied high temperature and large pressure may give rise to severe plastic deformation, viscous flow and creep of powder particles, which greatly contribute to the rapid densification of the amorphous 2Si-B-3C-N powder.

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Preparation and characterization of surface modified boron nitride epoxy composites with enhanced thermal conductivity

RSC Advances ◽

10.1039/c4ra07394k ◽

2014 ◽

Vol 4 (83) ◽

pp. 44282-44290 ◽

Cited By ~ 169

Author(s):

Jun Hou ◽

Guohua Li ◽

Na Yang ◽

Lili Qin ◽

Maryam E. Grami ◽

...

Keyword(s):

Mechanical Properties ◽

Thermal Conductivity ◽

Thermal Stability ◽

Boron Nitride ◽

High Thermal Conductivity ◽

Epoxy Composites ◽

Surface Modified ◽

Enhanced Thermal Conductivity ◽

Electrical Insulation Properties

The fabricated surface modified boron nitride epoxy composites exhibit high thermal conductivity, superior thermal stability and good mechanical properties while retaining good electrical insulation properties.

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Surface modification of a BN/ETDS composite with aniline trimer for high thermal conductivity and excellent mechanical properties

RSC Advances ◽

10.1039/c8ra03875a ◽

2018 ◽

Vol 8 (40) ◽

pp. 22846-22852 ◽

Cited By ~ 7

Author(s):

Seokgyu Ryu ◽

Taeseob Oh ◽

Jooheon Kim

Keyword(s):

Mechanical Properties ◽

Thermal Conductivity ◽

Surface Modification ◽

Boron Nitride ◽

Polymer Composites ◽

Conductive Polymer ◽

High Thermal Conductivity ◽

Conductive Polymer Composites ◽

Thermally Conductive

Boron nitride (BN) particles surface-treated with different amounts of aniline trimer (AT) were used to prepare thermally conductive polymer composites with epoxy-terminated dimethylsiloxane (ETDS).

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Recent Progress in the Study of Thermal Properties and Tribological Behaviors of Hexagonal Boron Nitride-Reinforced Composites

Journal of Composites Science ◽

10.3390/jcs4030116 ◽

2020 ◽

Vol 4 (3) ◽

pp. 116

Author(s):

Maryam Khalaj ◽

Sanaz Zarabi Golkhatmi ◽

Sayed Ali Ahmad Alem ◽

Kahila Baghchesaraee ◽

Mahdi Hasanzadeh Azar ◽

...

Keyword(s):

Thermal Conductivity ◽

Boron Nitride ◽

Recent Progress ◽

Phonon Scattering ◽

Hexagonal Boron Nitride ◽

High Thermal Conductivity ◽

Promising Candidate ◽

Reinforced Composite ◽

Low Thermal Expansion ◽

Wide Range

Ever-increasing significance of composite materials with high thermal conductivity, low thermal expansion coefficient and high optical bandgap over the last decade, have proved their indispensable roles in a wide range of applications. Hexagonal boron nitride (h-BN), a layered material having a high thermal conductivity along the planes and the band gap of 5.9 eV, has always been a promising candidate to provide superior heat transfer with minimal phonon scattering through the system. Hence, extensive researches have been devoted to improving the thermal conductivity of different matrices by using h-BN fillers. Apart from that, lubrication property of h-BN has also been extensively researched, demonstrating the effectivity of this layered structure in reduction of friction coefficient, increasing wear resistance and cost-effectivity of the process. Herein, an in-depth discussion of thermal and tribological properties of the reinforced composite by h-BN will be provided, focusing on the recent progress and future trends.

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Utilization of SiC and Cu Particles to Enhance Thermal and Mechanical Properties of Al Matrix Composites

Materials ◽

10.3390/ma12172770 ◽

2019 ◽

Vol 12 (17) ◽

pp. 2770 ◽

Cited By ~ 1

Author(s):

Dongxu Wu ◽

Congliang Huang ◽

Yukai Wang ◽

Yi An ◽

Chuwen Guo

Keyword(s):

Mechanical Properties ◽

Thermal Conductivity ◽

High Thermal Conductivity ◽

Low Density ◽

Matrix Composites ◽

Thermal And Mechanical Properties ◽

Cu Content ◽

Sic Particles ◽

Al Matrix Composites ◽

Al Matrix

In this work, SiC and Cu particles were utilized to enhance the thermal and mechanical properties of Al matrix composites. The ball-milling and cold-compact methods were applied to prepare Al matrix composites, and the uniform distribution of SiC and Cu particles in the composite confirms the validity of our preparation method. After characterizing the thermal conductivity and the compressibility of the prepared composites, results show that small particles have a higher potential to improve compressibility than large particles, which is attributed to the size effect of elastic modulus. The addition of SiC to the Al matrix will improve the compressibility behavior of Al matrix composites, and the compressibility can be enhanced by 100% when SiC content is increased from 0 to 30%. However, the addition of SiC particles has a negative effect on thermal conductivity because of the low thermal conductivity of SiC particles. The addition of Cu particles to Al-SiC MMCs could further slightly improve the compressibility behavior of Al-SiC/Cu MMCs, while the thermal conductivity could be enhanced by about 100% when the Cu content was increased from 0 to 30%. To meet the need for low density and high thermal conductivity in applications, it is more desirable to enhance the specific thermal conductivity by enlarging the preparation pressure and/or sintering temperature. This work is expected to supply some information for preparing Al matrix composites with low density but high thermal conductivity and high compressibility.

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