CERAMICS INTERNATIONAL
·
2019
·
IF 3.45
Zhimin An,Rubing Zhang,Daining Fang
The monolithic silicon carbide (SiC) aerogels were converted from catechol-formaldehyde/silicon composite (CF/SiO 2 ) aerogels through carbothermal reduction and calcination . In the process of preparing the CF/SiO 2 aerogel, a new method was proposed to produce more silicon carbide and enhanced the mechanical properties of the SiC aerogel. This method was realized by adding an alkaline silica sol as supplemental silicon source. The principle process of CF/SiO 2 aerogels converting to SiC aerogels was discussed based on experiment and results analysis, while the microstructure, mechanical properties, and thermal properties of the prepared SiC aerogels were investigated. The results show that the as-synthesized SiC aerogels consist of β-SiC and a small amount of α-SiC nanocrystalline . It possessed a mesoporous structure and a low thermal conductivity 0.049 W/(m∙K), a relatively high compressive strength 1.32 MPa, and a relatively high specific surface area 162 m 2 /g. Due to their outstanding thermal and mechanical properties, the prepared SiC aerogels present potential applications in thermal insulation field, such as space shuttles and aerospace carrier thermal protection materials.
研究领域:
材料科学
·
能源工程
✓ 已验证
产品关联
DOI
高影响因子
CERAMICS INTERNATIONAL
·
2025
·
IF 5.6
Xiao-Nan Zhou,Mu-Lun Wu,Xu Hao,Jia-Xin Li,Yu Song,Biao Zhang,Zhi-Lei Wei,Jian-Feng Yang,Bo Wang,Kozo Ishizaki
Hollow spherical SiC ceramics exhibit significant potential as multifunctional and structural materials. Herein, the β-SiC hollow spheres were synthesized by in-situ vapor-solid reaction (carbothermal reduction) between mesocarbon microbeads (MCMB) and SiO vapor generated from SiO powders, and subsequent removal of the residual carbon cores by oxidization. The diameter of SiC hollow spheres accurately inherits the size of pristine MCMB, demonstrating a shape memory effect. Meanwhile, the shell thickness of SiC hollow sphere can be autonomously regulated from 0.46 to 3.87 μm by adjusting the siliconization degree (corresponding to the content of SiO). In addition, a variety of characterizations were used to describe the phase and structure of SiC hollow spheres, confirming their high-purity. The SiC hollow spheres also exhibit a high specific surface area of 4.21 m 2 g −1 and good thermal stability. This technique presents a new paradigm in the preparation of hollow spheres.
研究领域:
材料科学
·
陶瓷
·
纳米材料
·
化学合成
·
热工工程
✓ 已验证
产品关联
DOI
高影响因子
AIP Advances
·
2023
·Vol. 13
·期 12
·
IF 1.6
Wang Ying,Yang Shuai,Li Xiang,Huang Wei,He Zheng-fa,Fu Xian-liang,Zhu Li,Xu Man
Developing a highly efficient water-splitting photocatalyst for hydrogen production under visible light is urgent. In this study, β-SiC nanowire photocatalysts loaded with 0.01–0.1 wt. % nickel were prepared. Their microstructure and hydrogen production activity were studied. The catalyst with 0.05 wt. % nickel and a sacrificial agent Na 2 S–Na 2 SO 3 shows the highest hydrogen production rate of 375.4 µ mol g −1 h −1 since the loaded nickel prohibits the recombination of photogenerated electron–hole pairs in the system, which enhances the photocatalytic activity.
✓ 已验证
产品关联
DOI
高影响因子
CERAMICS INTERNATIONAL
·
2021
·
IF 4.527
Jianrong Song,Gaoming Mo,Xiang Wu,Liu He,Qing Huang,Zhengren Huang
A liquid carbon-rich SiAlCN precursor is facilely synthetized by hydrosilylation between liquid polyaluminocarbosilane (LPACS) and 1,3,5,7-tetravinyl- 1,3,5,7-tetramethylcyclotetrasilazane {[CH 3 (CH 2 CH 2 )SiNH] 4 } (TeVSZ). The structural evolution during the polymer-ceramic conversion process is investigated by various methods. The results show that the main cured mechanism is β -addition on hydrosilylation, although α -addition on hydrosilylation, polymerization of vinyl groups and dehydrocoupling reaction between N–H bonds also occur during the cured process. During the pyrolysis process, dehydrogenation and dehydrocarbonation condensation reactions, transamination reactions occur, leading to formation of a three-dimensional network inorganic structure at 400–800 °C, where part of Al–O bonds convert to Al–N bonds. Then the network inorganic structure undergoes demixing and separation into amorphous SiAlCN(O) phase, where the amorphous turbostratic free carbon phase also form at 800–1200 °C. With demixing and decomposition of the amorphous carbon-rich SiAlCN(O) phase, the crystalline β-SiC and graphitic carbon start to form at about 1400 °C, the crystalline sizes of them both enlarge with increasing temperature. However, the crystal growth of β-SiC is distinctly inhibited due to existence of the rich carbon phase, tiny amounts of Al 2 O 3 and AlN . In addition, a small amount of AlN can promote the formation of α-SiC at 1800 °C.
研究领域:
材料科学
·
化学工程
✓ 已验证
DOI
高影响因子
JOURNAL OF ALLOYS AND COMPOUNDS
·
2022
·
IF 6.371
Jie Liu,Yurun Feng,Chunmiao Liu,Yanchun Tong,Haibin Sun,Hui Peng,Shigang Wu,Junbin Lu,Hongyu Gong,Xue Guo,Jiao Li
The SiBCN composite fibers with strong electromagnetic wave (EMW) absorption performance were successfully prepared via polymer-derived ceramics (PDCs) and electrospinning methods at relatively lower preparation temperature. The results showed that the in-situ generated free carbon which existed in the matrix in the form of simple substance and was characterized by low crystallinity. The graphite carbon improved the dielectric loss and properties of SiBCN composite fibers. In particular for the SiBCN composite fibers pyrolyzed at 1300 °C, the in-situ generated nano β-SiC crystallization increased the EMW absorption performance significantly. The minimum reflection loss (RL min ) of the SiBCN-3 reached − 54.91 dB at 2.35 mm and the effective absorption band (EAB, RL ≤ −10 dB) reached 4.72 GHz (13.28–18 GHz, 1.75 mm). Hence, the SiBCN fibers prepared at relatively lower temperature give good absorption performance and predict a broader application prospect in the field of EMW absorption materials.
研究领域:
材料科学
·
电磁学
✓ 已验证
产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）