ZEITSCHRIFT FUR ANORGANISCHE UND ALLGEMEINE CHEMIE
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2024
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IF 1.1
Ting Chen,Hanzi Du,Ralf Riedel,Zhaoju Yu
This work successfully fabricated a novel CNWs/Ni 2 Si/SiOC nanocomposite ceramic material using a single-source-precursor derived ceramic approach. The material exhibits in-situ formation of carbon nanowires (CNWs) and multiple core-shell nanoparticles such as Ni 2 Si@C and SiC@C. The reaction mechanism of the precursor, the microstructure and phase composition, and the ceramics′ electromagnetic wave (EMW) absorbing properties were thoroughly investigated and discussed. The obtained CNWs/Ni 2 Si/SiOC nanocomposite ceramics possesses a minimum reflection loss (RLmin) of −43.5 dB, indicating excellent EMW absorbing performance. The in-situ formation of CNWs and multi-core-shell nanoparticles (Ni 2 Si@C and SiC@C) in the ceramics play a crucial role in enhancing their EMW absorbing properties compared to pure SiOC ceramics.
研究领域:
材料科学
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电磁学
✓ 已验证
产品关联
DOI
高影响因子
Inorganic Chemistry Frontiers
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2019
·Vol. 7
·期 1
·82-90
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IF 5.934
Xiao Chen,Shuhua Han,Dongdong Yin,Changhai Liang
Based on the isolation of the active sites in the crystal structure as well as the strong alteration of the electronic structure in comparison to elemental metals, metal silicides as typical intermetallic compounds have boosted their applications in catalysis. Heterogeneous Ni2Si/SiCN as a promising and low-cost catalyst alternative to noble-metals has been successfully synthesized via the chemical modification of a polysilazane precursor at a molecular level by the use of metal complexes followed by its temperature-programmed pyrolysis. In the one-pot tandem synthesis of imines and secondary amines via the reductive coupling of nitrobenzene and benzaldehyde, the as-prepared Ni2Si/SiCN-1000 catalyst exhibits excellent catalytic performance (conversion >99% and selectivity to aromatic amine >92%) and excellent recyclability under optimal reaction conditions. Due to the reduction induction support–metal strong interactions and the formation of intermetallic Ni2Si, the electronic structure of the metallic Ni active site has been modified, which may tone the catalytic performance and enhance the stability of the catalyst.
研究领域:
材料科学
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催化化学
✓ 已验证
产品关联
DOI
高影响因子
CERAMICS INTERNATIONAL
·
2022
·
IF 5.532
Xue Guo,Junbin Lu,Jie Liu,Chunmiao Liu,Yanchun Tong,Jiao Li,Haibin Sun,Hui Peng,Shigang Wu,Yurun Feng,Hongyu Gong
By utilizing polymer-derived ceramics (PDCs) method and electrospinning technology, SiCN(Ni) fibers with 1 wt% nickel content at different calcination temperatures (1000–1300 °C) were synthesized. The properties of PDCs-SiCN(Ni) fibers were tested by XRD , SEM, TEM, Raman spectroscopy , XPS and vector network analyzer. The results showed that the addition of nickel acetylacetonate (NA) promoted the in-situ formation of CNTs and Ni 2 Si at high temperatures, which could adjust the impedance matching performance and improve the electromagnetic wave (EMW) absorption properties. The minimum reflection loss (RL) of SiCN(Ni) fibers was −47.55 dB (4.2 mm), and the effective absorption band (EAB, RL ≤ −10 dB) was 3.6 GHz (14.4–18 GHz) under the ultra-thin thickness of 1.24 mm.
研究领域:
材料科学
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电磁学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF ALLOYS AND COMPOUNDS
·
2024
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IF 5.8
Wenyan Huang,Jiahao Hu,Yeqi Zhu,Jiahua Zhan,Rongdan Lei,Yuchen Sun,Kaiqi Chen,Siqi Lan,Rongqian Yao
As contemporary aerospace and radar-detecting technologies evolve, load bearing-microwave absorption integration of thermal protection materials for complex environment requirements are urgent. Well known for low density, good high-temperature resistance and superior tunable dielectric properties, polymer-derived ceramics (PDCs) promisingly meet most needs of high-performance aircraft thermal protection system (TPS). Aimed at promoting practical application, we integrate in-situ formed Ni 2 Si into lightweight SiC(rGO) nanocomposite PDCs via re-pyrolyzing coassembled nano-Ni/SiC(rGO) p /polycarbosilane-vinyltriethoxysilane-graphene oxide (PVG) blends to enhance their mechanical and electromagnetic wave (EMW) absorbing performances. Size effect on phase transition of Ni into Ni 2 Si (as brazing bonding agents) accompanied by volumetric expansion, ingeniously eliminates stretching stress from PVG precursor inward shrinkage for compact framework during re-pyrolysis. In-situ generated Ni/Ni 2 Si/C core-shell nanostructure (similar to nodular cast iron) has good chemical compatibility with β-SiC/SiO x C y /C free (rGO), thereby enables composites improved compactness and toughness. More interestingly, heterogeneous interfaces/defects among Ni, Ni 2 Si, carbon shell, β-SiC and SiO x C y /C free (rGO) matrix, effectively facilitate interfacial/dipole polarization for robust EMW absorption, and lightweight SiC(rGO, Ni 2 Si) Ni=4% nanocomposite PDCs exhibit outstanding fracture toughness of 6.56 MPa·m 1/2 and high compressive strength of 119.25 MPa. Such composite with structure-function integration maintain stable under butane blowtorch at ∼1300 °C, shedding light on a new route to mass-manufacture aerospace vehicle components.
研究领域:
材料科学
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航空航天工程
✓ 已验证
产品关联
DOI
高影响因子
COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS
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2024
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IF 4.9
Chunmiao Liu,Yanchun Tong,Chang Liu,Meng Xu,Haibin Sun,Shigang Wu,Yujun Zhao,Jiao Li,Xue Guo,Yurun Feng
Faced with severe electromagnetic wave (EMW) pollution, the development of high-performance EMW absorbers remains a formidable challenge. In this study, SiBCN/Ni fibers containing uniformly dispersed Ni 2 Si nanoparticles were synthesized by electrospinning method with polymer-derived ceramics method, and their electromagnetic properties were evaluated. The low permeability threshold of the fibers ensures sufficient conduction loss effect. The in situ grown Ni 2 Si nanoparticles provide a magnetically coupled network, which is more conducive to obtaining excellent impedance matching. Furthermore, the presence of β-SiC, SiO 2 , and Si 2 N 2 O generates numerous heterogeneous interfaces (e.g., C-SiC and C-Ni 2 Si), leading to enhanced interfacial polarization through the accumulation of charges. As a result, the prepared SiBCN/Ni fibers exhibit impressive EMW absorption properties . At a Ni content of 1 wt%, the effective absorption band (EAB) is 4.32 GHz (13.68–18 GHz). At a Ni content of 1.5 wt%, the minimum reflection loss (RL min ) is −52.98 dB, and the sample has excellent radar scattering capabilities, which is verified by CST Microwave Studio simulations. Therefore, SiBCN/Ni fibers are promising as excellent EMW absorbing materials in practical applications.
研究领域:
材料科学
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电磁学
✓ 已验证
产品关联
DOI
高影响因子
ChemCatChem
·
2017
·Vol. 9
·期 7
·1337-1342
·
IF 4.803
Kaixuan Yang,Xiao Chen,Lei Wang,Liangliang Zhang,Shaohua Jin,Changhai Liang
Graphical Vapor trail : Metal silicide (Pd 2 Si, Ni 2 Si, CoSi, Fe x Si, and Cu 6.69 Si) catalysts supported by SBA-15 are prepared by chemical vapor deposition. Of the SBA-15-supported metal silicide catalysts, Ni 2 Si/SBA-15 presents a modest activity, notable selectivity to styrene (>90 %), and high stability in the selective hydrogenation of phenylacetylene. Metal silicide (Pd 2 Si, Ni 2 Si, CoSi, Fe x Si, and Cu 6.69 Si) catalysts supported by SBA-15 have been prepared by a chemical vapor deposition method under a H 2 atmosphere using (CH 3 ) 2 SiCl 2 as the Si source. Of the SBA-15-supported metal silicide catalysts, Ni 2 Si/SBA-15 presented a modest activity, notable selectivity to styrene (>90 %), and high stability with respect to the selective hydrogenation of phenylacetylene, which is attributed to the active-site isolation and electron transfer in the silicide. Furthermore, Ni 2 Si/SBA-15 also has a high selectivity to diphenylacetylene and 1,4-butynediol, which demonstrates that Ni 2 Si/SBA-15 is a promising, low-cost catalyst alternative to noble-metal catalysts as a selective hydrogenation catalyst.
研究领域:
催化化学
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材料科学
✓ 已验证
产品关联
DOI
高影响因子
CERAMICS INTERNATIONAL
·
2023
·
IF 5.2
Jie Liu,Guodong Wang,Chunmiao Liu,Yanchun Tong,Chang Liu,Haibin Sun,Shigang Wu,Yujun Zhao,Xue Guo,Yurun Feng
The biomass porous carbon (BPC)/polymer-derived composite ceramics with lightweight and efficient electromagnetic waves (EMW) absorbing performance was prepared by using sorghum straw as the absorbing matrix and combining the magnetic precursor acetylacetone nickel (NA) with polysilazane (PSZ). The results showed that when the doped content of NA was 2% and the filler content was 30%, the sample exhibited strong response to EMW. The minimum reflection loss (RL min ) reached − 69.44 dB at the thickness of only 1.33 mm, and the effective absorption bandwidth (EAB) at 1.49 mm was 4.27 GHz (13.73–18 GHz). In addition, the RL min at 4.22 m was −45.80 dB at low frequency. The EAB between 4.20 mm and 5 mm remained above 2.4 GHz and the widest reached 2.48 GHz. The in-situ generated Ni 2 Si effectively adjusted the impedance matching of the sample, and jointly regulated the conductivity with graphite carbon. The biomass porous carbon material matrix with large specific surface area, CNTs and Ni 2 Si provided large numbers of heterogeneous interfaces, which promoted interfacial polarization and dipole polarization. In addition, the introduction of Ni endowed magnetic loss, and a variety of loss mechanisms improved the EMW absorbing properties of the Ni/PDCs/BPCs composites.
研究领域:
材料科学
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电磁学
·
环境科学
✓ 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）