SCRIPTA MATERIALIA
·
2023
·
IF 6
Shenglin Kang,Xuetong Zhao,Jing Guo,Yongjian Xiao,Yang Yang,Binlang He,Xilin Wang,Lijun Yang,Ruijin Liao
Silica (SiO 2 ) glass has a wide range of industrial applications due to its outstanding optical, physicochemical, and electrical properties. Herein, a transparent SiO 2 glass with a high relative density of 96.8% is fabricated at 200 °C by cold sintering with a transient chemistry of H 2 SiO 3 , and a visible light transmittance of ∼80%, Vickers hardness of 3.1 (±0.14) GPa and Young's modulus of 45.6 (±2.7) GPa are achieved. Moreover, it is found that the transition from glass phase to crystallized ceramic occurs between 200 o C and 300 °C during the cold sintering process. The microstructural analysis shows an obvious phenomenon of recrystallization, accompanying by a formation of polygonal α-quartz grains of ∼150 nm. Meanwhile, the α-quartz ceramic presents an enhanced Vickers hardness and Young's modulus of 5.7 (± 0.13) and 60.2 (± 3.2) GPa, respectively. This work provides an efficacious way for designing SiO 2 glass and ceramics at low sintering temperatures .
研究领域:
材料科学
·
无机化学
✓ 已验证
DOI
高影响因子
COMPOSITES SCIENCE AND TECHNOLOGY
·
2017
·
IF 4.873
Song He,Guoxiang Sun,Xudong Cheng,Huaming Dai,Xianfeng Chen
Silica aerogel is an excellent thermal insulation material for its mesoporous nanostructures In this study, the aramid fibers were grafted with the mesoporous structure of silica aerogel to reduce the fiber thermal conductivity through a serious process. X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR) results indicate that siloxane groups were successfully grafted onto the fiber surface through nitration , reduction and grafting with 3-glycidoxypropyltrimethoxysilane (GPTMS). After cohydrolysis with tetraethyl orthosilicate (TEOS), condensation, alkylation and ambient drying, SEM images of the as-prepared fibers showed that a mesoporous structure formed around the fiber surface. Si content within the as-prepared fiber was about 10.5 times higher than the fiber grafted with GPTMS. The fiber was covered with a mesoporous and hyperbranched network. As a result, the thermal conductivity of blanket consisting of the as-prepared aramid fibers, measured by transient hot-wire method, was obviously lower than that of the original ones, whereas the thermal stability changes little.
研究领域:
材料科学
·
热绝缘材料
✓ 已验证
DOI
高影响因子
JOURNAL OF SOL-GEL SCIENCE AND TECHNOLOGY
·
2017
·Vol. 83
·期 3
·545-554
·
IF 1.575
Li Shanghong,Zhang Lei,Li Ji,Wu Ze,Yang Chunhui
Abstract Silica aerogels are utilized in the industry and scientific investigations. However, most silica aerogels are brittle, which hinders their development and application. In this paper, we reported the design and synthesis of a silica aerogel composite reinforced with silica nanowires by using two silicon sources: propyltriethoxysilane and tetraethoxysilane. The effects of varying silica nanowires contents on the properties of the silica aerogel composites were studied and compared with those of neat silica aerogel under identical conditions. The composites were obtained by mixing silica nanowires with hybrid silica sol without surface modification and dried in ambient atmosphere. The samples showed low density (0.172 g cm −3 ), high porosity (over 90%), and super hydrophobicity (the water contact angle reached 153°). The cross-linked silica aerogel composites showed excellent mechanical behavior and can be compressed by as high as 70% of their initial length before they were broken. The maximum completely recoverable compressive strain reached 50%. The elastic modulus of the optimal silica nanowires/silica aerogel composite increased by 67% (from 0.21 to 0.35 MPa) compared with that of the neat silica aerogel. The cross-linked propyltriethoxysilane and tetraethoxysilane can be used to synthesize new types of elastic silica aerogels, and the excellent performance of the silica nanowires/silica aerogels composite will enable its application in various fields. Graphical Abstract
研究领域:
材料科学
·
化学工程
✓ 已验证
产品关联
DOI
高影响因子
CERAMICS INTERNATIONAL
·
2024
·
IF 5.1
Xianxi Li,Liwen Yan,Anran Guo,Haiyan Du,Feng Hou,Jiachen Liu
Thermal protection was always a prominent issue in the aerospace industry. For vehicle safety, reliability and payload requirements, thermal protection materials were usually expected to possess low density, superior mechanical and thermal insulation properties. Here, lightweight and high-strength porous mullite-silica ceramics were manufactured using particle-stabilized foaming technique. The strength and thermal insulation properties of porous ceramics modified with hollow silica spheres were significantly enhanced. A 10 wt% hollow spheres addition achieved a 28.9 % increase in strength and a 33.4 % decrease in thermal conductivity with almost constant porosity (from 86.39 % to 87.04 %). Considering the characteristics of light weight, high compression strength and superior thermal insulation performance, porous ceramics could be applied as thermal protection materials in the aerospace sector.
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
Heliyon
·
2023
·
IF 4
Panpan Zhang,Jinghua Liu,Chunjing Zhou,Zebin Xue,Yifan Zheng,Haodong Tang,Zongjian Liu
Three types of Co 3 O 4 catalyst, namely Co 3 O 4 nanoparticles (denoted as Co 3 O 4 -NPs, ∼12 nm in diameter), Co 3 O 4 nanoparticles encapsulated in mesoporou s SiO 2 (denoted as Co 3 O 4 @SiO 2 ), and Co 3 O 4 nanoparticles inside microporous SiO 2 hollow sub-microspheres (denoted as Co 3 O 4 -in-SiO 2 ), were explored to catalyze the combustion of lean methane. It was found that the methane conversion over the three catalysts has the order of Co 3 O 4 -NPs ≈ Co 3 O 4 @SiO 2 > Co 3 O 4 -in-SiO 2 due to the different catalyst structure. The comparison experiments at high temperatures indicate the Co 3 O 4 @SiO 2 has a significantly improved anti-sintering performance. Combined with the TEM and BET measurements, the results prove that the presence of the mesoporous SiO 2 layer can maintain the catalytical activity and significantly improve the anti-sintering performance of Co 3 O 4 @SiO 2 . In contrast, the microporous SiO 2 layer reduces the catalytical activity of Co 3 O 4 -in-SiO 2 possibly due to its less effective diffusion path of combustion product. Thus, the paper demonstrates the pore size of SiO 2 layer and catalyst structure are both crucial for the catalytical activity and stability.
研究领域:
催化化学
·
材料科学
✓ 已验证
DOI
高影响因子
JOURNAL OF PHYSICS AND CHEMISTRY OF SOLIDS
·
2011
·
IF 1.384
Chuanyi Tao,Xueming Li,Wenjing Yang
Hook-shaped and straight silica wires have been successfully synthesized on silicon wafer through a simple thermal vapor method with or without assistance of Al , respectively. The hook-shaped silica wires have amorphous structures with nearly 100 μm long and about 4 μm in average diameters, while the straight silica wires are hundreds of micrometers long and approximately 50–300 nm in diameters. The composition analysis revealed that larger Al/SiO x islands can form on the silicon substrate with Al catalysts, whereas tiny silica clusters form without Al catalysts. They could act as the nucleation centers for the growth of silica wires with different shapes. The formation process of hook-shaped silica microwire results from a thermal gradient on the silicon substrate. The thermal gradient may be caused by the cold gas flowing during the process or other factors that lead to uneven temperature. On the contrary, straight growth of silica submicrowire is unacted on the thermal gradient factor due to the tiny silica clusters as nucleation centers. The present simple and low-cost process of producing hook-shaped and straight silica wires in bulk may lead to potential applications in catalysts, electrode materials, biosensing, etc.
研究领域:
材料科学
·
纳米技术
✓ 已验证
产品关联
DOI
高影响因子
CATALYSIS COMMUNICATIONS
·
2019
·
IF 3.674
Qianhe Liu,Qing Liu,Xun Hu
Successive hydrogenation of furfural in two fixed-bed reactors connected in tandem with Cu/SiO 2 and Ni/SiO 2 as the catalysts was achieved under atmospheric pressure. Various targeting products including furfuryl alcohol (yield: 98.8%), 2-methylfuran (yield: 95.1%), 2-methyltetrahydrofuran (yield: 96.2%) and tetrahydrofurfuryl alcohol (yield: 78.2%) could be obtained by variation of the reactor configurations.
研究领域:
化学工程
·
催化化学
✓ 已验证
产品关联
DOI
高影响因子
MATERIALS & DESIGN
·
2020
·
IF 6.289
Huafei Cai,Yonggang Jiang,Jian Feng,Sizhao Zhang,Fei Peng,Yunyun Xiao,Liangjun Li,Junzong Feng
Silica aerogels with different particle size were prepared by monodispersed silica sol for the first time. The properties of the silica aerogels under normal and high temperature were systematically studied. Among the four different particle size aerogels, the SA-2 sample consisted of 20.31 ± 1.21 nm particles with narrow size distribution had high temperature resistance and low thermal conductivity . Compared with the traditional acid-base two-step prepared silica aerogels, the monodisperse silica aerogels can significantly increase the temperature resistance while maintaining a low thermal conductivity (0.02723 W·m −1 ·K −1 ). The sturdy skeleton structure formed by the interconnection of large particles can effectively inhibit the viscous flow between aerogel particles and avoid pore collapse caused by skeleton failure which can maintain a stable structure until 900 °C and retain a relatively complete structure at 1000 °C with only about 35% volume shrinkage after 2 h heat treatment. At 1100 °C, the viscous flow between aerogel particles and pore collapse cannot be effectively suppressed, and the pure silica aerogels can only be used during a short period at 1100 °C. The results will be meaningful for the design of super thermal insulation materials with high temperature resistance and low thermal conductivity.
研究领域:
材料科学
·
热力学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF NON-CRYSTALLINE SOLIDS
·
2025
·
IF 3.5
Wang Zhan,Zhiyuan Xu,Xin Feng,Lixia Li,Qinghong Kong,Le Chen,Ru Zhou,Mingyi Chen,Juncheng Jiang
Based on the ice template method, ternary composite aerogels were prepared from fumed SiO 2 , gelatin, and polyimide. The purpose of the study is to improve the thermal-mechanical properties of the composite aerogel by adding fumed SiO 2 , and to construct a cross-linking network by gelatin and polyimide to further provide attachment sites for fumed SiO 2 . By this method, the thermo-mechanical properties of the composite aerogels were enhanced. The results show that when 2.4 g fumed SiO 2 is added and freezing rate at -7 °C/min, the composite aerogel demonstrates excellent thermal-mechanical properties.
研究领域:
材料科学
·
纳米技术
·
高分子科学
·
热力学
✓ 已验证
产品关联
DOI
高影响因子
ENERGY & FUELS
·
2023
·
IF 5.3
Wenhao Li,Dong Fu,Jiahong Pan
In recent years, the use of polyethylenimine (PEI)-functionalized adsorbents for CO2 capture from flue gas has gained significant attention due to its excellent adsorption capacity. However, the influences of suitable support materials and their morphology on the adsorption and desorption of CO2 have not been adequately explored. In this study, we investigate the impact of three nanostructures of SiO2 support, namely, silica nanospheres (SNPs), silica nanosheets (SNHs), and silica nanotubes (SNTs), on CO2 capture from ultralow emission flue gas, with special emphasis on key parameters such as the adsorption capacity, amine efficiency, kinetics, thermodynamics, cyclic stability, and optimal adsorption temperature to elucidate the crucial role of morphology. Experimental results demonstrated that SNHs facilitate the dispersion of PEI on their surface, thereby effectively utilizing the specific surface area and enhancing the dispersion of the active sites of PEI. This amine dispersion method successfully reduces the mass transfer resistance of CO2 during the adsorption process. Conversely, SNTs lead to PEI dispersion between support particles, resulting in increased diffusion resistance toward CO2 and consequently decreased adsorbent performance. For SNPs, the loading of PEI into the pores effectively prevented the degradation of the adsorption performance caused by PEI leaching during the cyclic use of the adsorbent. In addition, the larger pore volume of SNPs facilitated the loading of a greater number of PEI molecules. Notably, at 60 wt % PEI loading, SNPs exhibited a higher adsorption capacity (3.68 mmol/g), lower adsorption heat (51.91 kJ/mol), and reduced regeneration energy consumption (1.775 GJ/ton). This study sheds light on the role of the support morphology in adsorption processes and presents a novel strategy for designing solid amine adsorbents with favorable cycle stability, high CO2 capture performance, and efficient amine utilization.
研究领域:
环境科学
·
化学工程
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
Nanoscale Research Letters
·
2009
·Vol. 5
·期 1
·116-123
·
IF 1.731
Wu Wei,Xiao Xiangheng,Zhang Shaofeng,Fan Lixia,Peng Tangchao,Ren Feng,Jiang Changzhong
The development of synthetic process for hollow silica materials is an issue of considerable topical interest. While a number of chemical routes are available and are extensively used, the diameter of hollow silica often large than 50 nm. Here, we report on a facial route to synthesis ultrafine hollow silica nanoparticles (the diameter of ca . 24 nm) with high surface area by using cetyltrimethylammmonium bromide (CTAB) and sodium bis(2-ethylhexyl) sulfosuccinate (AOT) as co-templates and subsequent annealing treatment. When the hollow magnetite nanoparticles were introduced into the reaction, the ultrafine magnetic hollow silica nanoparticles with the diameter of ca . 32 nm were obtained correspondingly. Transmission electron microscopy studies confirm that the nanoparticles are composed of amorphous silica and that the majority of them are hollow.
研究领域:
材料科学
·
纳米技术
✓ 已验证
DOI
高影响因子
Polymers
·
2019
·Vol. 11
·期 7
·1211
·
IF 3.164
Heng Zhang,Junliang Lu,Hongyan Yang,Heng Yang,Jinyan Lang,Qinqin Zhang
The flame retardant dicyclohexenyl aluminum hypophosphite (ADCP) and nano-silica are added to PA66 to improve flame retardant property of the composite. The flame-retardant property of the composite is tested via oxygen index test, vertical burning test, and cone calorimetry test. Combustion residues are tested using scanning electron microscopy, EDS spectroscopy, and Fourier infrared analysis. Results show that flame-retardant ADCP can effectively promote the formation of a porous carbon layer on the combustion surface of PA66. Nano-silica easily migrates to the material surface to improve the oxidation resistance of the carbon layer and the density of the carbon layer’s structure. It can also effectively prevent heat, flammable gases, and oxygen from entering the flame zone and enhance the flame retardant properties of ADCP.Keywords:nano-silica;ADCP;synergetic flame-retardant;PA66
研究领域:
材料科学
·
燃烧学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
危险品化学品经营许可证（带存储）