Effects of Y2O3 and yttrium aluminates as sintering additives on the thermal conductivity of AlN ceramic substrates

Huang, Dong; Tian, Zhaobo; Cui, Wei; Long-qiao, Gao; Liu, Zheng; Diao, Xungang; Liu, Guanghua

doi:10.1016/j.ceramint.2018.07.178

Cited by 56 publications

(15 citation statements)

References 20 publications

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“…This indicates that SG maintains as its original graphitic structure in the sintered sample. The existence of Y 3 Al 5 O 12 is ascribed to be the reaction between Y 2 O 3 and Al 2 O 3 that exists on the surface of AlN, which not only promotes the liquid phase sintering of the AlN-based composite under a relatively low temperature, but also effectively removes the oxygen impurities in the lattice of AlN, thereby enhancing the thermal conductivity of the AlN-based composite ceramics [42,43].…”

Section: Phase Compositionmentioning

confidence: 99%

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: Phase Compositionmentioning

confidence: 99%

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

et al. 2021

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“…To sum up, the effect of strain rates induced by scratch speeds on deformation characteristics and damage mechanisms cannot be ignored. AlN ceramic is the polycrystalline material, which is liquid-phase sintered from numerous AlN grains with a few additives of yttrium oxide added to further improve the thermal conductivity and densification [ 31 , 32 ]. Its microstructure is completely different from other brittle materials such as silicon crystal and sapphire.…”

Section: Introductionmentioning

confidence: 99%

Effect of Strain Rate on the Deformation Characteristic of AlN Ceramics under Scratching

Gao

Kang

et al. 2021

Micromachines

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To clarify the influence mechanism of strain rate effect on deformation characteristics of aluminum nitride (AlN) ceramics, some varied-velocity nanoscratching tests were carried out using a Berkovich indenter in this paper. The deformation characteristics of the scratched grooves were observed using the scanning electron microscope. The experimental results showed higher scratch speed would lead to shallower penetration depth, fewer cracks, and indenter fewer slipping, which was more conducive to the plastic deformation of AlN ceramics. Considering the strain rate effect and the elastic recovery of material, a model for predicting the Berkovich indenter penetration depth under edge-forward mode was established. The prediction results were consistent with the experimental data, and the error was less than 5%, indicating that the model is effective. Based on the Boussinesq field, the Cerruti field, and the Sliding bubble field, a strain rate dependent scratch stress field model was established. The stress field revealed higher scratch speed may significantly reduce the maximum principal stress in the stress field under the indenter, which is the fundamental reason for reducing the crack damage and promoting the plastic deformation. The above study can provide theoretical guidance for reducing the processing damage of AlN ceramics.

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“…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. [25,26,27,28,29,30]. One of the most promising materials with all these characteristics is aluminum nitride [31,32,33,34,35].…”

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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Effects of Y2O3 and yttrium aluminates as sintering additives on the thermal conductivity of AlN ceramic substrates

Cited by 56 publications

References 20 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

Effect of Strain Rate on the Deformation Characteristic of AlN Ceramics under Scratching

Study of Helium Swelling in Nitride Ceramics at Different Irradiation Temperatures

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