JOURNAL OF SOL-GEL SCIENCE AND TECHNOLOGY
·
2021
·Vol. 99
·期 1
·169-177
·
IF 2.326
Cheng Ming,Liu Wensheng,Yao Shuwei,Wang Juan,Ma Yunzhu
Phase transformation is essentially important for the microstructures and properties of sol–gel prepared alumina fiber and powders. In this study, alumina precursor fiber and xerogels were prepared using the same aluminum carboxylate sol. The phase transformation and microstructure evolution of the precursor fibers and xerogels were investigated using TG-DSC, XRD, TEM, and SEM methods. The alumina precursor fiber and xerogels have similar chemical structures and Al(III) species. After preheated at 600 °C, most of the free water molecules, hydroxyl groups, nitrate acid radical, formic acid radicals, and acetic acid radicals are removed from the alumina precursor fiber and xerogels. The preheated fiber and xerogels exhibit amorphous phases. From the TG-DSC curves, the transformation temperature from γ-Al 2 O 3 to α-Al 2 O 3 in the preheated fiber is 30 °C lower than that in the preheated xerogels. The TEM results suggest that the fiber calcined at 1000 °C for 1 h can be completely transformed into α-Al 2 O 3 phase, while the xerogels need to be calcined at 1100 °C for 1 h to completely convert into the α-Al 2 O 3 phase. The difference in the phase transformation of the alumina fiber and xerogels was discussed in this paper.
研究领域:
材料科学
·
陶瓷学
✓ 已验证
产品关联
DOI
高影响因子
CHEMICAL ENGINEERING JOURNAL
·
2024
·
IF 13.3
Huan Xu,Cui Liu,Wei Guo,Nian Li,Yang Chen,Xiaolin Meng,Mengjie Zhai,Shudong Zhang,Zhenyang Wang
The severe environmental pollution issues require the urgent development of new green building insulation materials. Biomass aerogel is deemed as an optimal candidate to replace petroleum-based insulation materials owing to its significant advantages such as low thermal conductivity, eco-friendliness, and high biocompatibility. The interaction of the composite two-phase interface and the fabrication of multilevel pore structures have a significant impact on the comprehensive performance of aerogel applications. In this study, a tunable double-crosslinked network skeleton structure construction of sodium alginate (SA) composite with Al 2 O 3 fibers is proposed, where Ca 2+ induces the sol–gel transition to form a second layer of strong bonding force to effectively support the skeleton structure, and various cross-linking modes, such as ionic bonding, hydrogen bonding and physical cross-linking, are used to synergistically improve the SA aerogel and endow it with multifunctionality. The prepared Al 2 O 3 fiber/SA (SAA) aerogels achieve excellent flame retardancy and self-extinguishing smoke suppression (peak heat release rate as low as 9.7 kW m −2 , and total smoke release rate in the low range of 0.5 m 2 m −2 ). It also has superior mechanical strength (high specific compression modulus of ∼53.3 KN m kg −1 ) and can withstand weights over 2600 times its own weight without deformation, besides the broad range of self-cleaning properties and outstanding biocompatibility. The creation of a double-crosslinked three-dimensional aerogel network via reinforcement of inorganic electrospun fibers provides new insights for eco-friendly insulation materials in construction.
研究领域:
材料科学
·
环境科学
✓ 已验证
产品关联
DOI
高影响因子
Transactions of the Indian Ceramic Society
·
2022
·
IF 2.355
Qiang Liu,Juan Wang,Wensheng Liu,Lingjiao Zhan,Shaoheng Peng,Shuwei Yao,Yunzhu Ma
In order to optimize the phase composition and grain size of alumina fibers, 0-3 wt% SiO2 were induced to prepare alumina fibers using sol-gel method with the reaction of aluminium powder, formic acid, acetic acid, nitric acid and SiO2 sol. Effects of low SiO2 content on the phase transition and microstructure of alumina fibers were investigated. X-ray diffraction analysis and differential scanning calorimetry results showed that the addition of silica delayed the formation of α-Al2O3, and the phase transformation path of alumina was changed from amorphous alumina → γ-Al2O3 → α-Al2O3 to amorphous alumina → γ-Al2O3 → θ-Al2O3 → α-Al2O3. Moreover, scanning electron microscopy and transmission electron microscopy results confirmed that the addition of SiO2 reduced the grain size and was beneficial for the dense structure. Fine-grained dense alumina fibers composed of α-Al2O3 phase and transitional alumina phase were obtained by adding 1 wt% and 3 wt% silica after sintering at 1200°C for 1 h.
研究领域:
材料科学
·
陶瓷学
✓ 已验证
DOI
高影响因子
CERAMICS INTERNATIONAL
·
2020
·
IF 3.83
Chen Liang,Wensheng Liu,Qiang Liu,Yangrui Gao,Jijin Liu,Juan Wang,Shuwei Yao,Yunzhu Ma
Thermal decomposition is a critical process for fabricating alumina fibers using sol-gel methods. In this work, effects of preheating time on microstructure of prepared alumina fibers were studied. Results showed that core-sheath structure formed in the fibers when holding time exceeded 2 h at 400 °C. The fibers having core-sheath structure after thermal decomposition showed more residues, smaller crystal grain size and lower density. Thermal decomposition and densification of fibers were investigated. Results showed that core-sheath structure formed because fiber surface and core underwent different decomposition reactions due to the reduction in the number of gas channels on the fiber surface. This work provides a comprehensive study of thermal decomposition of precursor fibers and provides guidelines for developing appropriate calcination schedules.
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
COMPOSITES PART A-APPLIED SCIENCE AND MANUFACTURING
·
2021
·
IF 7.664
Li Fan,Shuai Zhang,Guojie Zhao,Qiang Fu
Various fillers and methods have been utilized to enhance the thermal conductivity ( TC ) of polymer-based electronic packaging materials, however, the enhancement was limited by disconnected pathway for phonon transferring. Herein, a novel fibrillated hybrid skeleton (f-AO@BNNS skeleton) was fabricated by dispersing boron nitride nanosheet (BNNS) into alumina (AO) sol, electrospinning and sintering, where long-range phonon transferring highway was successfully constructed by both macroscopically interconnected fiber and microscopically oriented and overlapped BNNSs confined in nanofiber . Besides, crystal AO and atomic-level bonding were acquired on BNNS-AO interface by sintering, largely decreasing interface thermal resistance inside skeletons. Prepared polybenzoxazine/f-AO@BNNS composites exhibited the highest TC of 3.24 Wm −1 K −1 at a skeleton loading of 6.9 vol%. The higher TC was achieved at lower filler content when compared with other reported skeletons, demonstrating the superiority of f-AO@BNNS skeleton. This work provides a new strategy of preparing fibrillated hybrid skeleton for high thermally conductive composites.
研究领域:
材料科学
·
热物理学
✓ 已验证
产品关联
DOI
高影响因子
SURFACE & COATINGS TECHNOLOGY
·
2012
·
IF 1.867
Guoxin Hu,Bo Tang,Xia Min
By using layer-by-layer self-assembly technology, multilayered films consisting of alternated humic acid and Fe 3 + ions ((HA/Fe 3 + ) n , n = 10,20,40) were fabricated on alumina fiber (AF) substrate for the first time. FTIR and FESEM results show that the (HA/Fe 3 + ) n thin films were effectively immobilized on the AF surface. The average thickness of a single bi-layer HA/Fe 3 + is not sensitive to the total layers. On the contrary, the concentration of Fe 3 + ions significantly influences this mean thickness. A loose and amorphous structure with some irregular pores was detected from the as-prepared specimens, while relatively smooth surface and denser structure were observed after carbonized at 1000 °C. The large BET surface areas and excellent absorbability of the as-prepared and carbonized samples were found. Moreover, at room temperature, a ferromagnetic property of these samples was revealed by magnetism testing. Due to the adjustable number of layers, the ferromagnetic property is controllable. Therefore, these produces possess potential application as the support material in catalytic and target drug delivery areas.
研究领域:
材料科学
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环境科学
✓ 已验证
产品关联
DOI
高影响因子
Materials
·
2020
·Vol. 13
·期 23
·5442
·
IF 3.057
Luqun Liu,Juan Wang,Yunzhu Ma,Wensheng Liu,Shuwei Yao
Continuous alumina fiber exhibits excellent mechanical properties owing to its dense microstructure with fine grains. In this study, alumina fiber was prepared by the sol–gel method using iron sol as a nucleating agent. It was proposed that the α-Al2O3grain size be adjusted based on the modification of colloidal particle size. The effect of holding temperature and reaction material ratio on the iron colloidal particle size was studied. The microstructure of alumina fiber was characterized by scanning electron microscopy (SEM). The experiment results indicated that iron colloidal particle size increases with the holding temperature and the NH4HCO3/Fe(NO3)3·9H2O ratio. The alumina fiber with uniform nano α-Al2O3grains was obtained by calcination at 1400 °C for 5 min. The mean grain size tends to rise with the mean colloidal particle size. Using the iron sol as a nucleating agent, the fiber with a mean grain size of 22.5 nm could be formed. The tensile strength of fibers increased with the decrease of grain size.Keywords:alumina fiber;iron sol;holding temperature;colloidal particle size;grain size
研究领域:
材料科学
·
陶瓷工程
✓ 已验证
产品关联
DOI
PubMed
高影响因子
CERAMICS INTERNATIONAL
·
2024
·
IF 5.1
Zhengdong Li,Xueying Zhang,Liwen Yan,Haiyan Du,Anran Guo,Ying Mu,Jiachen Liu
High emissivity coatings on hypersonic vehicle surfaces dissipate heat by emitting thermal radiation. While the difficulty of increasing emissivity limits the performance of coatings to improve heat-dissipation of the thermal insulation felt. Herein, a novel high-reflectivity and high-emissivity integrated double-layer coating was developed to enhance the thermal insulation performance of the alumina fiber fabric. The coating comprised of TiO 2 @SiO 2 (T@S) as reflective agent and ZrO 2 /SiC w (ZSC) as emittance agents, was applied on the surface of alumina fiber fabric (AFF). The reflecting effect of radiation heat from the high reflective agent enhanced the thermal insulation properties of the double-layer coating. In the wavelength range of 0.4–2.5 μm, the average emissivity of the ZSC coating was 0.83 and the average reflectivity of the T@S coating was 0.63. With continuous heating at 1400 °C for 10 min with a butane torch, the temperature on the backside of the T@S–ZSC-coated AFF remained relatively stable at 225 °C, which is notably decreased by 80 °C compared to that of the single-layer ZSC-coated AFF. The tensile strength of AFF with T@S–ZSC coating reached 35 MPa after being heat treated at 1200 °C. Moreover, the bonding strength between the coating and the AFF substrate was measured to be 0.15 MPa. The double-layer coating with high emissivity and reflectivity, along with a flexible AFF substrate, offers a promising solution for addressing the challenging of surface heat-dissipation in hypersonic vehicles.
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 SOL-GEL SCIENCE AND TECHNOLOGY
·
2022
·Vol. 103
·期 1
·125-138
·
IF 2.606
Ma Yunzhu,Peng Shaoheng,Liu Wensheng,Yao Shuwei,Wang Juan
Controlling the density and the nanograin size is challenging but essential to prepare continuous alumina fibers with excellent performance. In this study, the continuous alumina fibers were prepared using the sol-gel method. The fibers calcined under different conditions were characterized to reveal the effect of calcining conditions on the fiber microstructure evolution. The results show that the phase transformation from amorphous Al 2 O 3 to γ-Al 2 O 3 and then to α-Al 2 O 3 takes place during the calcining process. The fiber, prepared using a single-step calcining method, cannot obtain a fully dense and nanocrystal microstructure through optimizing the calcination conditions. Thus, a novel two-step calcining process was proposed, through which an almost fully dense α-Al 2 O 3 fiber with an average grain size of ~150 nm was prepared and the tensile strength of fibers reaches 2.2 GPa. Based on the results, the effect mechanism of residual organics, phase transformation, densifying, and grain growth on the fiber microstructure evolution was discussed in depth.
Graphical abstract
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
CERAMICS INTERNATIONAL
·
2021
·
IF 4.527
Chunlan Li,Wensheng Liu,Tao Luo,Ming Cheng,Qiang Liu,Juan Wang,Shuwei Yao,Yunzhu Ma
The structure and spinnability of sol are essential for obtaining high-performance continuous alumina-based fibres. Herein, the surface electrostatic potential analysis and conventional experimental methods (X-ray diffraction, Fourier-transform infrared spectroscopy, 27 Al nuclear magnetic resonance solution spectra and rheological methods) were combined to investigate and discuss the relationship between the structure and spinnability of aluminium carboxylate sols with different formic-acid-to-acetic-acid molar ratios. The results showed that the aluminium carboxylate sol structure changed with the formic-acid-to-acetic-acid molar ratio and greatly affected the sol's spinnability. The tetramer (AlO6 oligomer) products comprising two effective active carboxylate groups in the sol increased with the formic acid content, which helped form linear long-chain polymers. However, excess formic acid content led to a large increase of AlO6 monomer products that were unable to form linear long-chain polymers, which decreased the sol's spinnability. When the formic-acid-to-acetic-acid molar ratio was 1.15:0.85, the sol containing more AlO6 oligomer products had the best spinnability. Furthermore, α-Al 2 O 3 ceramic fibres with good morphology, small grains and uniform diameter distribution were obtained after calcination at 1200 °C.
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
Materials Research Express
·
2019
·Vol. 6
·期 4
·045207
·
IF 1.449
Jing Liu,Yunzhu Ma,Wensheng Liu,Xiaolei Song,Shuwei Yao,Juan Wang,Ming Cheng,Chunlan Li
Precursor sol with a high solid content is significant for alumina fiber synthesis. In the present work, alumina precursor sols used for preparing alumina fibers were synthesized by dissolving aluminum powder (AP) into a mixture of formic acid, acetic acid and deionized water. The effects of preparation temperatures on solubility of AP, structure of the synthesized sols and gels were investigated. The reaction mechanism of hydrolysis and polymerization was also studied. Based on the reaction mechanism, alumina precursor sol with a high solid content was acquired through the adjustment of temperature. The results revealed that all the sols synthesized at the temperature from 85 °C to 115 °C consisted of polymers, linear oligomers and monomeric species. Colloidal particles presented spherical shape with a uniform size. However, AP cannot dissolve entirely at 85 °C and white precipitates (HO)Al(CH3COO)2 was produced at 105 °C and 115 °C. AP had the highest dissolution degree at 95 °C. A colorless and transparent alumina sol with the highest solid content was acquired at this temperature. The structure of concentrated gels was also discussed. It was revealed that network polymers increased when using sols synthesized at temperature above 105 °C, which were negative for spinning. Continuous green fibers were obtained successfully using the alumina sol prepared at 95 °C.
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
·
2023
·
IF 5.2
Huihui Yan,Kun Wang,Liping Zhao,Peng Zhang,Jing Liu,Lian Gao
Flexible aluminum oxide (Al 2 O 3 ) fibers were prepared by the blow spinning method and their potential as a high-temperature catalyst support was investigated. The synthesized Al 2 O 3 fibers exhibited remarkable flexibility in both mechanical compression and recovery tests, which remained intact in a wide temperature range from −196 °C to 1200 °C. Moreover, their low thermal conductivity of 0.030 W K −1 ∙m −1 , demonstrated an outstanding thermal insulation . Subsequently, nickel nanoparticles were uniformly distributed on the surface of the Al 2 O 3 fibers as a self-supporting catalyst using a conventional impregnation method. The resulting self-supporting Ni/Al 2 O 3 catalyst demonstrated remarkable thermo-catalytic performance and re-activation capability at high temperatures for thermocatalytic reaction of dry reforming of methane (DRM). Our findings highlight the potential of pure Al 2 O 3 flexible fibers as a versatile material for various industrial applications, including high-temperature catalysis.
研究领域:
材料科学
·
催化化学
·
能源技术
✓ 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）