JOURNAL OF THE EUROPEAN CERAMIC SOCIETY
·
2022
·
IF 6.364
Liang Wang,Wei-Ming Guo,Peng-Fei Sheng,Li-Fu Lin,Xiao Zong,Shang-Hua Wu
A new type of non-oxide sintering additive of YH 2 was introduced for the fabrication of AlN ceramics with high thermal conductivity and flexural strength . The effects of YH 2 addition (0–5 wt%) on the phase composition, densification, microstructure, thermal conductivity and flexural strength of pressureless sintered AlN ceramics were investigated and compared with those Y 2 O 3 -added samples (1–5 wt%). The addition of 1 wt% YH 2 led to an in-situ reduction reaction with oxygen impurities, the formation of Y 2 O 3 and finally the formation of yttrium aluminate, which in turn improved densification and microstructure. A high flexural strength (408.69 ± 28.23 MPa) was achieved. The addition of 3 wt% YH 2 increased the average grain size and purified the lattice. All these effects are believed to help achieve a high thermal conductivity of 184.82 ± 1.75 W·m −1 ·K −1 . Although the thermal conductivity was close to the value of 3 wt% Y 2 O 3 -added sample, its strength was much increased to 381.53 ± 43.41 MPa. Meanwhile, it demonstrated a good combination of the thermal conductivity and flexural strength than the values reported in some literature. However, further increasing the YH 2 addition to 5 wt% resulted in a high N/O ratio that inhibited the densification behavior of AlN ceramics. The current study showed that AlN ceramics with excellent thermal and mechanical properties could be obtained by the introduction of a suitable YH 2 additive.
研究领域:
材料科学
·
陶瓷工程
✓ 已验证
DOI
高影响因子
JOURNAL OF THE AMERICAN CERAMIC SOCIETY
·
2020
·Vol. 103
·期 10
·5567-5572
·
IF 3.502
Weide Wang,Dongxu Yao,Hanqin Liang,Yongfeng Xia,Kaihui Zuo,Jinwei Yin,Yu-Ping Zeng
A two-step sintering process was conducted to produce β-Si 3 N 4 ceramics with high thermal conductivity. During the first step, native SiO 2 was eliminated, and Y 2 O 3 was in situ generated by a metal hydride reduction process, resulting in a high Y 2 O 3 /SiO 2 ratio. The substitution YH 2 for Y 2 O 3 endow Si 3 N 4 ceramics with an increase of 29% in thermal conductivity from 95.3 to 123 W m −1 K −1 after sintered at 1900°C for 12 hours despite an inferior sinterability. This was primarily attributed to the purified enlarged grains, devitrified grain boundary phase, and reduced lattice oxygen content in the YH 2 -MgO-doped material.
研究领域:
材料科学
·
陶瓷工程
✓ 已验证
DOI
高影响因子
JOURNAL OF THE EUROPEAN CERAMIC SOCIETY
·
2020
·
IF 4.495
Weide Wang,Dongxu Yao,Hanqin Liang,Yongfeng Xia,Kaihui Zuo,Jinwei Yin,Yu-Ping Zeng
The effect of YH 2 on densification, microstructure, and thermal conductivity of Si 3 N 4 ceramics were investigated by adjusting the amount of YH 2 in the range of 0–4 wt% using a two-step sintering method. Native SiO 2 was eliminated, and Y 2 O 3 was in situ formed by a metal hydride reduction reaction, resulting in various Y 2 O 3 /SiO 2 ratios. Full densification of YH 2 -doped samples could be achieved after sintering at 1900 °C for 4 h. The Y 2 O 3 /SiO 2 ratio had a significant influence on the composition of crystalline secondary phases. Besides, the increased Y 2 O 3 /SiO 2 ratio is conducive not only to the grain growth but also to the reduction of activity of SiO 2 in the liquid phase, resulting in enlarged purified grains, reduced volume fraction of intergranular phases and increased Si 3 N 4 -Si 3 N 4 contiguity. Ultimately, the thermal conductivity increased by 29 % from 95.3 to 123.0 W m −1 K −1 after sintering at 1900 ℃ for 12 h by the substitution of Y 2 O 3 with YH 2 .
研究领域:
材料科学
·
热传导工程
✓ 已验证
DOI
高影响因子
Coatings
·
2026
·Vol. 16
·期 5
·543
·
IF 3.4
Wei Zhang,Baozhen Yang,En Zhu,Feibiao Yu
A three-factor, four-level orthogonal design was employed to optimize the overall forming quality of powder bed fusion with a laser beam (PBF-LB)-fabricated TC4 alloy containing 0.3 wt.% YH2. Sixteen process-parameter combinations were established, and two specimens were fabricated for each combination. Laser power, scanning speed, and hatch spacing were selected as the investigated variables. Relative density, surface roughness, and Vickers hardness were evaluated using the entropy weight method combined with the weighted-sum method. On this basis, the microstructure of the specimens produced under the optimal process parameters was systematically characterized. The results showed that the influence of the investigated factors on overall forming quality followed the order: hatch spacing > laser power > scanning speed. The optimal process parameters were a laser power of 200 W, a scanning speed of 1100 mm/s, and a hatch spacing of 0.10 mm, under which the specimens exhibited superior overall forming quality. The addition of 0.3 wt.% YH2did not significantly alter the dominant phase constitution of the alloy, but promoted α′ martensite refinement and weakened the texture through the in situ formation of Y2O3nano-oxide particles.
✓ 已验证
DOI
高影响因子
Ceramics-Switzerland
·
2026
·Vol. 9
·期 6
·58
·
IF 2.8
Zizheng Cai,He Ma,Kun Tian,Feng Sun,Lijuan Zhou,Shuang Li
Sintering additives play a decisive role in the densification behavior, mechanical properties, and thermal conductivity of silicon nitride ceramics. In this study, Mg2Si and YH2were used as sintering additives for gas pressure sintering of silicon nitride based on the synergistic mechanism of “silicide silicon extraction-hydride dehydrogenation”. The regulation rules of the additives on ceramic densification, mechanical properties, and thermal conductivity were systematically investigated. Two optimization strategies were proposed for the technical route of replacing traditional oxide additives with non-oxide systems. (i) Rare-earth hydride YH2was used to replace traditional rare-earth oxides. It reacts with SiO2to achieve strong deoxidation and precisely regulate the liquid phase composition. (ii) Metal silicide Mg2Si was used to replace metal oxides. It promotes the preferred growth of β-Si3N4grains, consumes oxygen in the system, and reduces lattice defects. Mg2Si introduces Si into the liquid phase, increasing the Si/O ratio, which lowers lattice oxygen content and supports higher thermal conductivity. YH2consumes SiO2on the Si3N4surface, which reduces liquid phase oxygen content and inhibits lattice oxygen incorporation, promoting a liquid phase with a high N/O ratio. Compared with traditional Y2O3, YH2increases the Y2O3/SiO2ratio in the liquid phase. It promotes grain growth, reduces SiO2activity, and further improves the thermal conductivity of ceramics. Silicon nitride ceramics prepared by gas pressure sintering at 1750 °C with 3 wt.% Mg2Si and 4 wt.% YH2composite additives exhibit the highest thermal conductivity of 87 W/(m·K), with a Vickers hardness of 14.36 GPa and a flexural strength of 643.15 MPa. This study provides an innovative idea for the preparation of high-performance silicon nitride heat dissipation substrates.
✓ 已验证
DOI
高影响因子
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