JOURNAL OF ALLOYS AND COMPOUNDS
·
2019
·
IF 4.175
Huiwen Xiong,Lianzhong Zhao,Hehao Chen,Xiaofeng Wang,Kechao Zhou,Dou Zhang
3D SiC-based lattices with aligned SiC whiskers were prepared via direct ink writing of SiC w /polycarbosilane (PCS)-based suspensions. Suspensions with different solid loading were prepared and used to investigate the morphology and printability of 3D SiC w /SiC lattices. Filaments with the morphologies of accumulation, coiling, meandering and straight were achieved with different printing height and speed. Higher printing height favored the formation of coiled filaments with longer periodic structure and increased amplitude. 3D lattices with straight filaments and good retention of shape were achieved only when applying a suitable printing parameters for SiC w /PCS-based suspensions with a solid loading of 62.3 vol%. The resulted 3D lattices with the porosity around 62% showed impressive bending and compression strength of 33.2 ± 5.2 MPa and 30.6 ± 4.3 MPa, respectively. The satisfactory properties of 3D SiC w /SiC lattices were contributed by the pullout of the aligned SiC whiskers. Furthermore, this 3D technique via the Polymer-derived Ceramics (PDCs) route allows the fabrication of large sized samples, which opens new opportunities for the fabrication of 3D structures with unique mechanical and functional properties in practical dimensions.
研究领域:
材料科学
·
工程学
✓ 已验证
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
·
电磁学
✓ 已验证
产品关联
DOI
高影响因子
Journal of Materials Chemistry C
·
2021
·Vol. 9
·期 38
·13509-13519
·
IF 7.393
Shaohong Chen,Xichao Dong,Xiaoji Yao,Pengfei Wu,Anhua Liu,Zhaoju Yu
Improving the electromagnetic wave (EMW) absorption performance of continuous SiC fibers is of great significance for the development of structure-function integrated composites. Doping magnetic metal elements into SiC fibers can effectively improve their dielectric/magnetic loss, which is expected to produce SiC fibers with wide frequency EMW absorption. At present, introducing metal into continuous SiC fibers generally has the disadvantages of (1) low metal content and (2) weak EMW absorption ability. In this paper, vinylferrocene (VF) with monofunctional groups was selected as the iron source to introduce Fe atoms into polycarbosilane (PCS) through chemical modification without changes in the molecular framework of PCS, which is beneficial for the melt spinning of the precursors. A series of continuous Fe-SiC fibers were prepared by polymer-derived ceramic approach, and their composition, structure and EMW properties were systematically studied. Besides SiC crystallization, the turbostratic carbon, core–shell structures of Fe5Si3@C and Fe3Si@C were identified for the continuous Fe-SiC fibers. It is worth noting that in the present work, (1) the introduction of Fe catalyzes the formation of turbostratic carbon, which can be observed at a low temperature of 900 °C and (2) the highest Fe content (7.70 wt%) was obtained among all the reported continuous Fe-SiC fibers. The unique microstructure of final Fe-SiC fibers demonstrated outstanding EMW absorbing performance. For the Fe-SiC-2-900 °C fiber, the minimum reflection loss (RLmin) reached −54.63 dB at 10.2 GHz. By adjusting the thickness, the effective absorption bandwidth of Fe-SiC-3-1200 °C can almost cover the X-band. The results indicate that the presented continuous Fe-SiC fibers exhibit excellent EMW absorbing performance.
研究领域:
材料科学
·
电磁学
✓ 已验证
DOI
高影响因子
JOURNAL OF ALLOYS AND COMPOUNDS
·
2024
·
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
·
航空航天工程
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF ALLOYS AND COMPOUNDS
·
2021
·
IF 5.316
Lingjie Li,Zhonghao Ning,Wenyan Huang,Liang Liao,Yinong Zheng,Kun Zhuang,Siqi Lan,Yinggan Zhang,Rongqian Yao
An ingenious strategy to prepare in-situ formed SiC(Al, rGO) bulk polymer-derived ceramics (PDCs) from re-pyrolyzing SiC(Al, rGO) p /polyaluminocarbosilane-vinyltriethoxysilane-graphene oxide (PACS-VTES-GO, PAVG) blends is highlighted. Flexible PAVG modified by Al with highly cross-linked structure effectively improves molecular weight and formability of precursors. Rigid SiC(Al, rGO) p fillers provide high mechanical properties owing to their unique microstructure which is consistent with SiC(Al, rGO) bulk PDCs. β-SiC nanocrystals are well dispersed in amorphous SiO x C y /C free , and rGO exhibits good compatibility with SiO x C y /C free . Besides, possible Al 2 O 3 is beneficial to relaxing thermal stress at β-SiC nanocrystalline boundaries. Interestingly, introduction of Al could avoid coarsening of β-SiC grains to enhance elevated temperature resistance. Furthermore, effect of re-pyrolysis temperature on the formation and microstructure of SiC(Al, rGO) bulk PDCs was also investigated. Particularly, lightweight samples re-pyrolyzed at 1300 °C display optimal fracture toughness (3.32 MPa m 1/2 ), compressive strength (177.16 MPa) and flexural strength (51.25 MPa), high ceramic yield (94.46%) and low linear shrinkage (4.38%), by far superior to those of most PDCs. As treated via precursor infiltration and pyrolysis (PIP) route and heated by butane gun flame in air, such products possess stable structures under elevated temperatures and have potential emerging uses in aerospace components.
研究领域:
材料科学
·
航空航天工程
✓ 已验证
产品关联
DOI
高影响因子
ENVIRONMENTAL RESEARCH
·
2024
·
IF 7.7
Muhammad Idrees,Saima Batool,Hina Rasheed,Indika Herath,Jochen Bundschuh,Nabeel Khan Niazi,Mahtab Ahmad,Junguo Xu,Deliang Chen
Nano-zerovalent iron (nZVI) is a promising material for the removal of both organic and inorganic pollutants from contaminated water. This study investigates the potential of a novel composite of nZVI on a polymer-derived supporting ceramic (nZVI-PDC) synthesized via the liquid-phase reduction method for the simultaneous adsorption and Fenton-type reduction of bromate anion (BrO 3 − ) in water. The nZVI nanoparticles were effectively anchored onto the PDC by impregnating high-yield carbon in a ferrous sulfate solution . The PDC facilitated the uniform dispersion of nZVI nanoparticles due to its multiple active sites distributed within mesocarbon cavities. The developed nZVI-PDC composite exhibited a high specific surface area of 837 m 2 g −1 and an ordered mesoporous structure with a pore volume of 0.37 cm 3 g −1 . As an adsorbent, the nZVI-PDC composite exhibited a maximum adsorption capacity (q e ) of 842 mg g −1 and a partition coefficient (K H ) of 10.2 mg g −1 μM −1 , as calculated by the pseudo-second-order model. As a catalyst, the composite demonstrated a reaction kinetic rate of 43.5 μmol g −1 h −1 within 6 h at pH 4, using a dosage of 60 mg L −1 nZVI-PDC and a concentration of 0.8 mmol L −1 H 2 O 2 . Comparatively, PDC exhibited a q e of 408 mg g −1 , K H of 1.67 mg g −1 μM −1 , and a reaction rate of 20.8 μmol g −1 h −1 , while nZVI showed a q e of 456 mg g −1 , K H of 2.30 mg g −1 μM −1 , and a reaction rate of 27.2 μmol g −1 h −1 . The modelling indicated that the nZVI-PDC composite followed pseudo-second-order kinetics. The remarkable removal efficiency of the nZVI-PDC composite was attributed to the synergistic effects between PDC and nZVI, where PDC facilitated charge transfer, promoting Fe 2+ generation and the Fe 3+ /Fe 2+ cycle. Overall, this work introduces a promising adsorption technology for the efficient removal of BrO 3 − from contaminated aqueous solutions, highlighting the significant potential of the nZVI-PDC composite in water purification applications.
研究领域:
环境科学
·
材料科学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
MATERIALS AND MANUFACTURING PROCESSES
·
2022
·
IF 4.783
Jian Liu,Shufeng Xiong,Hui Mei,Zhangwei Chen
The combination of polymer-derived ceramics and DLP 3D printing has significant advantages for manufacturing special polynary ceramics with complex structures. However, a large number of the organic components in the precursor rapidly burn out and release after evaporation during pyrolysis. This leads to structural retention issues such as sample deformation, shrinkage and cracking. The surface morphology and accuracy of the sample are greatly affected by the escape of organic matter and the release of thermal stress during the pyrolysis process. Therefore, this study employs the method of adding low-melting-point silicone oil based on the original material components. The slow burn-out process of silicone oil at a lower temperature can produce fine pores, which would aid the release of thermal stress. Additionally, it can provide channels for escape of the organic gas at high-temperature, which helps to reduce large deformation and cracking and improves the surface morphology and dimensional accuracy of the final pyrolyzed samples. The method studied in this work helps to enhance the structural retention of complex-shaped polymer-derived ceramics manufactured by 3D printing and high-temperature pyrolysis, which could be beneficial to the further mass fabrication of such ceramic products.
研究领域:
材料科学
·
制造工程
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF ALLOYS AND COMPOUNDS
·
2022
·
IF 6.371
Jimei Xue,Song Hu,Xiaoping Li,Fei Li,Yuqiang Liu,Hanjun Wei
Polymer derived SiCN ceramics (PDC SiCN) are the key high-temperature matrix materials for structural and stealth integrated ceramic matrix composites (CMC). However, low crystallization degree and homogeneous microstructure of PDC SiCN ceramics results in the lack of effective microwave attenuation mechanism. Hence, a new kind of nonmagnetic metal oxide (Y 2 O 3 ) was in-situ formed in SiCN ceramics to enhance the conductivity loss as well as the polarization loss. Y 2 O 3 modified PDC SiCN ceramics (SiCN-Y 2 O 3 ceramics) were fabricated by pyrolysis polysilazane with different Y(NO 3 ) 3 content at 900 ºC. For the SiCN-Y 2 O 3 ceramic, Y 2 O 3 nanoparticles were dispersed in SiCN ceramic uniformly forming a large number of Y 2 O 3 -SiCN heterogeneous amorphous interface, defects and dipole polarization to enhance its microwave absorbing properties. Due to the multiple polarization loss mechanism, SiCN-Y 2 O 3 ceramic with 10 wt% Y(NO 3 ) 3 content achieved excellent microwave absorption performance at a wide thickness range with the microwave absorbing efficiency more than 90% in the whole X band, and the RC min could reach − 50.2 dB at the thickness of 3.5 mm.
研究领域:
材料科学
·
电磁学
✓ 已验证
产品关联
DOI
高影响因子
Materials
·
2023
·Vol. 16
·期 3
·1053
·
IF 3.4
Yanpei Dang,Tianhao Li,Yangzhong Zhao,Liantai Duan,Jianning Zhang,Ke Chen,Liu He,Qing Huang,Chuanzhuang Zhao,Yujie Song
Polyborosilazanes with controllable B/N ratio were synthesized using high-boron-contentm-carborane, dichloromethylsilane, and hexamethydisilazane. After high-temperature pyrolysis, Si–B–C–N quaternary ceramics with SiC and B4C as the main phases were obtained. The B/N ratio in the precursors corresponded to the change in the feeding ratio of carborane and dichloromethylsilane. The effects of boron content and B/N ratio on the ceramic precursors and microphase structure in Si–B–C–N quaternary ceramics were explored in detail through a series of analytical characterization methods. A high boron content results in a significant increase in the ceramic yield (up to 71 wt%) of polyborosilazanes, and at the same time, the B/N molar ratio was regulated from 28.4:1 to 1.62:1. The appearance of the B4C structure in the Si–B–C–N quaternary ceramics through the regulation of the B/N ratio, has rarely been reported.Keywords:polyborosilazane;SiBCN;carborane;polymer derived ceramics;B/N ratio;microphase evolution
研究领域:
材料科学
·
化学工程
·
陶瓷
✓ 已验证
产品关联
DOI
PubMed
高影响因子
JOURNAL OF THE AMERICAN CERAMIC SOCIETY
·
2023
·Vol. 106
·期 11
·6951-6961
·
IF 3.9
Yuangao Yan,Xuan Fei,Liuying Huang,Yuxi Yu,Yichen Wen,Gang Zhao
Hexagonal boron nitride (h-BN) with low dielectric loss and high temperature resistance opens up new opportunities for the preparation of polymer-derived SiCN ceramics (PDCs-SiCN ceramics) with excellent mechanical and dielectric properties. BN-containing polymer-derived SiCN composite ceramics (PDCs-SiCN(BN) composite ceramics) with different BN content were prepared via a pyrolysis process of ball-milling-blended Polyvinylsilazane/boron nitride (PVSZ/BN) precursors. BN is stably embedded in the SiCN tissue and tightly bound with it. The appropriate content of BN greatly improves the mechanical properties of PDCs-SiCN ceramics, as BN reduces the number of pores and prevents crack expansion. Additionally, BN is also beneficial in lowering the dielectric loss of PDCs-SiCN ceramics because of the weakened polarization relaxation behavior. PDCs-SiCN (BN) composite ceramics have optimal mechanical and dielectric properties when the BN content is 1 wt%. The flexural strength, flexural modulus and compression strength of PDCs-SiCN(BN) composite ceramics with 1 wt% BN doping content were 189.37 MPa, 46.38 GPa, and 399.02 MPa, respectively. Its average dielectric loss (tanδ ε ) at 12.4-18 GHz is 0.0049.
研究领域:
材料科学
·
陶瓷工程
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF ALLOYS AND COMPOUNDS
·
2023
·
IF 6.2
Nannan Zhu,Lijuan Zhang,Guangwu Wen,Yongzhao Hou
The mechanism of SiC whiskers-enhanced polymer-derived ceramics prepared by digital light processing (DLP) was investigated. The results showed that the introduction of SiC whiskers can significantly improve the mechanical properties of SiCO ceramic. When the content of SiC whiskers in the precursor photosensitive resin varied from 0 to 5 wt%, the bending strength of samples increased from 44.2 ± 4.1 MPa to 260.1 ± 49.7 MPa, and the fracture toughness improved from 1.48 ± 0.03 MPa·m 1/2 to 3.23 ± 0.12 MPa·m 1/2 , respectively. The Weibull modulus of the precursor composite ceramics prepared by DLP technology was 10.45. The mechanisms of SiC whisker toughening of SiCO ceramics mainly include fracture and pull-out of the whisker, deflection, bridging of cracks, the directional distribution of whiskers, and compressive stress of the SiC whisker on the ceramic matrix. This work will have important guiding significance for the industrial application of additive manufacturing precursor composite ceramics.
研究领域:
材料科学
·
增材制造
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF THE AMERICAN CERAMIC SOCIETY
·
2020
·Vol. 103
·期 8
·4063-4068
·
IF 3.502
Bin Du,Honghua Liu,Yanhui Chu
Polymer-derived ceramic (PDC) route has been widely used to fabricate various ceramics or ceramic-matrix composites in recent years. However, the synthesis of high-entropy ceramics via PDC route has rarely been reported until now. Herein, we successfully synthesized a class of high-entropy carbides, namely (Hf 0.25 Nb 0.25 Zr 0.25 Ti 0.25 )C (HEC-1), via PDC route. The polymer-derived HEC-1 ceramics consisted of numerous superfine particles with the average particle size ~800 nm. Meanwhile, they possessed a rock-salt structure of metal carbides and high-compositional uniformity from nanoscale to microscale. In addition, the as-obtained HEC-1 ceramics had a low oxygen impurity content of 0.51% and a low free carbon impurity content of 2.56%. This work will open up a new research field on the fabrication of high-entropy ceramics or high-entropy ceramic-matrix composites via PDC route.
研究领域:
材料科学
·
陶瓷工程
✓ 已验证
DOI
高影响因子
危险品化学品经营许可证（带存储）