Thermal Conductivity and High-Frequency Dielectric Properties of Pressureless Sintered SiC-AlN Multiphase Ceramics

Jia-lin, GU; Sang, Lingling; Pan, Bo; Feng, Yongbao; Yang, Jian; Li, Xiaoyun

doi:10.3390/ma11060969

Cited by 19 publications

(9 citation statements)

References 27 publications

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“…In comparison with other AlN-based attenuating ceramics, the thermal properties of AlN-based composites containing different attenuating agents are tabulated in Table 1. Generally, the λ values of the SG/AlN composites are significantly higher than that of AlN/SiC attenuating composite ceramics (40 to 70 W•m -1 •K -1 [1,10,11]) at the same content of the second phase. Simultaneously, in comparison to the AlN-based composites containing 1D/2D carbon materials, such as graphene and carbon nanotubes, as the second phase www.springer.com/journal/40145 This work [7][8][9], at the same content, the SG/AlN composite shows a relatively higher λ as well.…”

Section: Thermal Propertiesmentioning

confidence: 90%

“…However, the addition of SiC not only increases the heterogeneous interface, but also generates a SiC/AlN solid solution. As a result, the SiC/AlN composites develop a large interface, high thermal resistance, and numerous crystal defects, which would cause severe phonon scattering and the deterioration of thermal conductivity of the SiC/AlN composite attenuating ceramics [1,10,11].…”

Section: Introduction mentioning

confidence: 99%

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

et al. 2021

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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 (3D) 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 3D 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 −13.9 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.

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Section: Thermal Propertiesmentioning

confidence: 90%

Section: Introduction mentioning

confidence: 99%

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

et al. 2021

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“…In the X-band, as the SG content increases from 0 wt% to 8 wt%, the RLmin of the composites gradually decreases first, and then increases. When the SG content is SG content (wt %) R C 1 C 2 2 1.623×10 10 1.038×10 -11 3.…”

Section: Microwave Absorption Propertiesmentioning

confidence: 99%

“…where Z0 is the impedance in free space, and Zin is the incident impedance of the material surface, which can be obtained from Equation 10 (10) where f refers to the frequency of the electromagnetic wave, c is the speed of light (3×10 8 m/s), d denotes the material thickness, and εr and μr are the complex permittivity and complex permeability of the material, respectively (for non-magnetic materials, μr is commonly set to 1) [70]. RL is generally a negative value, and the smaller the value is, the stronger the absorption ability of the material.…”

Section: Microwave Absorption Propertiesmentioning

confidence: 99%

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

Xia

Jiang

Pan

et al. 2020

Preprint

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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·m 1/2 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.

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“…In recent years, more and more research has been devoted to the study of radiation resistance and defect formation processes in ceramic materials based on nitrides or carbides [22,23,24,25,26,27,28]. The interest in these materials is due to the possibility of their use as structural materials of high-temperature nuclear reactors, due to the high melting temperature (above 2000–2500 °C), insulation characteristics, resistance to aggressive media, etc.…”

Section: Introductionmentioning

confidence: 99%

Study of Helium Swelling in Nitride Ceramics at Different Irradiation Temperatures

2019

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This paper presents the results of a systematic study of helium swelling and the subsequent process of degradation of the near-surface layer of aluminum-based nitride ceramics. The samples were irradiated with 40 keV He2+ ions at temperatures of 300 and 1000 K with a fluence of 1 × 1017–5 × 1017 ions/cm2. The choice of radiation doses and temperature conditions was due to the possibility of simulating reactor tests of structural materials. It has been established that an increase in the irradiation fluence leads to the formation of large agglomerates of clusters of helium bubbles, as well as an increase in the degree of roughness and waviness of the surface with the formation of crater-like inclusions. In the case of irradiation at high temperatures, there was a slight decrease in the average size of helium inclusions compared with irradiation at room temperature. However, the density of inclusions and surface roughness were much higher. It is established that irradiation at room temperatures leads to a sharp decrease in ceramics density, as well as deformation of the crystal structure due to an increase in the density of dislocations and macrostresses in the structure. The decrease in ceramics density due to the formation of helium inclusions led to an increase in porosity and a defective fraction in the structure of the surface layer of ceramics.

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Thermal Conductivity and High-Frequency Dielectric Properties of Pressureless Sintered SiC-AlN Multiphase Ceramics

Cited by 19 publications

References 27 publications

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

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

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

Study of Helium Swelling in Nitride Ceramics at Different Irradiation Temperatures

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