CONSTRUCTION AND BUILDING MATERIALS
·
2024
·
IF 7.4
Yuntao Fu,Chen Qiu,Long Ni,Hang Ye,Huawei Zou,Yinfu Luo,Mei Liang
Lightweight and excellent mechanical properties rigid polyurethane foams (RPUFs) play an irreplaceable role in aerospace, construction and transportation fields. Microstructure is an important factor in controlling properties of RPUFs. In this study, RPUFs with different cell structures were fabricated by adjusting foaming agent. The relationship between cell structure parameters (cell size, wall thickness, closed cell rate and cell anisotropy) and density was determined based on SEM analysis. The compressive, bending, impact, heat insulation and sound insulation properties were tested. The results showed that cell structure was related to mechanical properties, which was reflected in the linear relationship between log (density) and log (mechanical properties). RPUF 0.4 with a density of 148 kg/m 3 possessed excellent compressive strength, flexural strength, flexural modulus and impact strength of 2.89 MPa, 2.60 MPa, 35.41 MPa and 1.06 kJ/m 2 . Thermal and sound insulation properties were depended on cell size and closed cell rate, the thermal conductivity of RPUFs ranged from 0.0398 to 0.0515 W/(m·K), and the sound transmission loss of RPUF 1.4 exceeded 25 dB in 500–5000 Hz. The comprehensive properties were regulated by adjusting cell structure, which provides a theoretical basis for the design of RPUFs with specific properties.
研究领域:
材料科学
·
工程学
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产品关联
DOI
高影响因子
JOURNAL OF APPLIED POLYMER SCIENCE
·
2015
·Vol. 132
·期 45
·
IF 1.768
Mengye Cao,Hualin Wang,Ruizhi Cai,Qing Ge,Suwei Jiang,Linfeng Zhai,Shaotong Jiang
This work aimed to develop a novel epoxy-modified tung oil waterborne insulation varnish with blocked hexamethylene diisocyanate as a curing agent. The Diels–Alder reaction between tung oil and maleic anhydride, and the ring-opening esterification reaction of epoxy resin were confirmed. The conversion rate of epoxy was explored as a function of reaction time and temperature. The effects of epoxy resin content on the thermal stability, water absorption and insulation properties (insulation strength, volume resistivity, and surface resistivity) of films were investigated, and the resistances of films to salted water were evaluated. The increase in epoxy resin contents could improve the thermal stability and insulation properties of films, and decreased the water adsorption of films, but when the epoxy resin content reached 30% and above, the water solubility of resin became poor. After being immersed in 3.5 wt % NaCl solution, the electrical insulation strength of films were lower than that in dry state, and decreased as the immersed time prolonged. In particular, the electrical insulation strength loss of films increased significantly for epoxy resin content at 15% and below. Furthermore, the increase of epoxy resin content could improve the hardness and adhesion of films, but the flexibility of films became worse. On the basis of experimental, the epoxy resin content at 25% was appropriate to prepare waterborne epoxy-modified tung oil resin. The resulting varnish may have potential as an immersing insulation varnish for the spindle of electric motor. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132 , 42755.
研究领域:
材料科学
·
化学工程
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产品关联
DOI
高影响因子
JOURNAL OF SOL-GEL SCIENCE AND TECHNOLOGY
·
2019
·Vol. 92
·期 3
·652-661
·
IF 1.986
Li Xiaohua,Yang Zichun,Li Kunfeng,Zhao Shuang,Fei Zhifang,Zhang Zhen
In this paper, transparent flexible hydrophobic silica aerogels were prepared by replacing the traditional alcohol solvent with water, using methyltriethoxysilane (MTES) and cetyltrimethylammonium bromide (CTAB), via acid-base two steps method and CO 2 supercritical drying. The role of surfactant CTAB in the gel–sol process was revealed, and the effect of CTAB concentration on the gel structure was analyzed. With the concentration increasing, the skeleton structure of the gel gradually changed from coarse graininess to continuous fiber. The obtained aerogels showed good elastic properties. With the increasing of density, the elastic modulus of aerogels gradually increased, so that the length could be restored to 63% of the original length after 50% compression strain. Aerogels also had low thermal conductivity and good thermal stability. The thermal conductivity at room temperature was only 0.0215 W/(m·K) and the initial decomposition temperature was up to 511 °C. For the aerogel with thickness of 11.8 mm and density of 60 mg/cm 3 , it showed good sound absorption and sound insulation properties. When the sound frequency was 2000 Hz, the sound absorption coefficient was 0.91, and the sound transmission loss between 500 and 1600 Hz was 13–21 dB. This work provides a facile approach to fabricate lightweight and flexible silica aerogels for thermal and acoustic insulation applications.
研究领域:
材料科学
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化学工程
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产品关联
DOI
高影响因子
POLYMER
·
2024
·
IF 4.1
Huilong Shao,Zhifang Fei,Zhen Zhang,Xiaohua Li,Guobing Chen,Kunfeng Li,Shuang Zhao,Zhongyi Luo,Zichun Yang
As a nanoporous material, polyimide (PI) aerogels have excellent thermal and acoustic properties. However, their high air flow resistance is detrimental to the development of their acoustic properties. To enhance the thermal and acoustic insulation properties of PI aerogels, we have selected hollow glass microbeads (HGM) with a low thermal conductivity coefficient to be combined with the PI aerogel, leading to the fabrication of PI/HGM aerogel composite materials. In this study, there are two preprocessing methods for HGM: untreated and aminized (HGM-NH 2 ). These were then individually combined with PI aerogel to fabricate two distinct PI/HGM composite aerogels: a physically blended variant (PIHGM) and a chemically bonded one (PHN). The thermal insulation and acoustic properties of these two composite aerogels were compared. The results show that HGM-NH 2 not only functions as a cross-linking agent but also plays a key role in forming the three-dimensional network structure, which effectively reduces the shrinkage rate and density of the composite aerogel. Moreover, the thermal conductivity of PHN reached a low of 27.92 mW m⁻ 1 K⁻ 1 , which is a reduction compared to PIHGM's thermal conductivity of 29.83 mW m⁻ 1 K⁻ 1 . Moreover, the PHN composite aerogel with 10% HGM addition exhibited an average sound insulation level that was 120% higher than that of PIHGM. The method of incorporating pore structures with different scales also offers valuable insights for enhancing the sound insulation performance of other materials.
研究领域:
材料科学
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热能工程
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声学工程
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产品关联
DOI
高影响因子
Materials Today Communications
·
2023
·
IF 3.8
Junyao Zhang,Yaqiang Dong,Yanqiu Li,Liping Yang,Xingjie Jia,Ling Zhang,Lingwen Cai,Aina He,Jiawei Li,Xincai Liu,Baogen Shen
Currently, power electronic devices are developing to meet the requirement of miniaturization, high-frequency and low-power consumption, reducing the high-frequency loss of soft magnetic powder cores (SMPCs) is one of the popular research topics. The construction of multilayer insulating structures can reduce the core loss ( P cv ) of SMPCs by increasing the resistivity. In this work, a composite inorganic insulating layer of phosphate and TiO 2 was successfully synthesized on the powder surface by phosphating and then sol-gel method. At last a nanocrystaline SMPCs with excellent soft magnetic properties were prepared with epoxy resin as the binder. The cores were heat-treated at 510 ℃ for 1 h to achieve optimum soft magnetic properties, with a low P cv of 854 mW/cm 3 at 20 mT and 2 MHz, an effective permeability ( μ e ) of 40 at 10 MHz and excellent DC bias with a percent permeability of 74% of the initial value at 100 Oe. The synergistic effect of the epoxy - TiO 2 - phosphate - nanocrystalline powder multilayer interface effectively reduces inter-particle eddy current loss, resulting in a significant reduction in the P cv of the SMPCs.
研究领域:
材料科学
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电磁学
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产品关联
DOI
高影响因子
npj Quantum Materials
·
2022
·Vol. 7
·期 1
·1-8
·
IF 6.856
Zhang Wenhao,Gao Jingjing,Cheng Li,Bu Kunliang,Wu Zongxiu,Fei Ying,Zheng Yuan,Wang Li,Li Fangsen,Luo Xuan,Liu Zheng,Sun Yuping,Yin Yi
The electronic evolution of doped Mott insulators has been extensively studied for decades in search of exotic physical phases. The proposed Mott insulator 1 T -TaS 2 provides an intriguing platform to study the electronic evolution via doping. Here we apply scanning tunneling microscopy (STM) to study the evolution in Ti-doped 1 T -TaS 2 at different doping levels. The doping Ti atom locally perturbs the electronic and spin state inside the doped star of David and induces a clover-shaped orbital texture at low-doping levels ( x < 0.01). The insulator to metal transition occurs around a critical point x = 0.01, in which small metallic and large insulating domains coexist. The clover-shaped orbital texture emerges at a broader energy range, revealing a competition with the electron correlation. It transforms to a disorder-induced Anderson insulating behavior as doping increases. We directly visualize the trapped electrons in d I / d V conductance maps. The comprehensive study of the series of Ti-doped 1 T -TaS 2 deepens our understanding of the electronic state evolution in a doped strong-correlated system.
研究领域:
凝聚态物理
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材料科学
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表面科学
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电子结构
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量子材料
✓ 已验证
DOI
高影响因子
CERAMICS INTERNATIONAL
·
2021
·
IF 4.527
Zhichun Liu,Junsheng Liang,Shijie Su,Chaoyang Zhang,Jian Li,Mingjie Yang,Sen Cao,Hao Zhou,Kuipeng Zhao,Dazhi Wang
Ultra-high temperature thin-film sensors（ UTTSs ）have drawn enormous attention due to their wide application prospect in multiple physical parameters monitoring in harsh environment. As an important part of UTTSs , the insulation film between workpiece and sensors plays a crucial role to ensure the accuracy of UTTS s. High insulation resistance ( IR ) is essential for the reliability improvement of the UTTSs and the reduction of their testing error. However, the defects in the insulation film will form the conductive path between the sensors and their mounting surface at high temperature, leading to a rapid IR drop and stability deterioration of the insulation film. In this work, 10 μm thick alumina film was prepared with suspension made out of alumina gel and alumina nano-powder using layer-by-layer electrohydrodynamic jet ( E-jet ) deposition ( LLED ). By adopting this technique, the process defects in one layer can be remedied in situ by the next deposition layer. The prepared film shows satisfactory insulation performance at elevated temperature, and IR of the film can reach 80 MΩ, 3 MΩ and 38 kΩ at 500 °C, 800 °C and 1200 °C, respectively. The thickness-normalized IR of the alumina film at 800 °C in this work is at least 7.8 times that obtained by other methods reported in the literatures. Moreover, after subjected to three thermal cycles from room temperature to 1200 °C, the IR of the film can still remain at 14 kΩ. The high performance of the alumina insulation film in this work can be attributed to the effective reduction of the minor defects in the LLED deposition process.
研究领域:
材料科学
·
电气工程
·
传感技术
✓ 已验证
产品关联
DOI
高影响因子
IEEE TRANSACTIONS ON DIELECTRICS AND ELECTRICAL INSULATION
·
2024
·
IF 2.9
Shuang Hu,Zhuang Fu,Jiawen Zhang,Yihua Qian,Hongmei Wang
The combination of phenolic and amine additives represents a traditional approach for the co-formulation of antioxidant compounds in insulating oils. However, the introduction of amines not only induces significant alterations in the inherent characteristics of the oil but also gives rise to aging by-products that are environmentally detrimental. This study examines the aging behavior of three commonly employed phenolic antioxidants, namely BHT, BHA, and TBHQ, when added individually or in combination to synthetic ester insulating oil. The investigation reveals that the co-formulation of phenolic antioxidants demonstrates exceptional antioxidant efficacy within synthetic ester insulating oil. Through the oxidative stability test, it is observed that incorporating a combination of 0.3 wt% BHT and 0.1 wt% BHA into the oil maintains the dielectric dissipation factor at 0.681%, representing a mere 0.202% increase compared to fresh oil. Furthermore, the total acid number can be sustained at 0.01 mg KOH/g, and the breakdown voltage can be up to 78 kV. This study employs linear sweep voltammetry (LSV) and Fourier-transform infrared spectroscopy (FT-IR) to analyze the behavior of antioxidants and the degradation products of aged oil samples. A preliminary investigation into the synergistic antioxidant mechanism of phenolic antioxidants in synthetic ester insulating oil is conducted, to provide a novel approach for the formulation of antioxidant compounds.
研究领域:
化学工程
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材料科学
✓ 已验证
产品关联
DOI
高影响因子
ACS Applied Materials & Interfaces
·
2025
·
IF 8.2
Wen-Rui Li,Xiong Yang,Guang-Yu Sun,Yu-Cheng Zhang,Hao-Yan Liu,Xiao-Gang Qin,Bai-Peng Song,Guan-Jun Zhang
Improving the surface insulation strength of substrate material polyimide (PI) is an effective strategy to suppress charging and discharging effects of spacecraft solar arrays. To meet the insulation requirements of next-generation spacecraft with higher voltage levels, the surface insulation of PI must be further improved. Herein, we propose an approach to control the surface roughness and pore distribution of PI using a pore-forming agent. Modulating surface roughness and pore distribution effectively suppresses secondary electron emission avalanches, greatly enhancing surface insulation strength. When the pore-forming agent addition ratio is 50%, the film features the highest flashover threshold of 55.93 kV, a 201.7% improvement over the PI films currently used in spacecraft. The maximum secondary electron yield decreased from 2.01 to 1.32. Additionally, this novel porous PI film is exceptionally lightweight and possesses excellent electrical and thermal properties. The thermal equilibrium temperature is up to 13.44% lower than that of PI films currently used in spacecraft. Even after high- and low-temperature thermal shock, its mechanical properties and flashover performance remain highly stable. The novel polyimide films hold great potential for future applications in insulation of space solar arrays.
研究领域:
材料科学
·
航天工程
·
高分子材料
·
电气绝缘
·
热控材料
✓ 已验证
产品关联
DOI
PubMed
高影响因子
CRYSTENGCOMM
·
2019
·Vol. 21
·期 38
·5749-5756
·
IF 3.382
Wen Zeng,Haojie Lai,Tianyin Chen,Yueheng Lu,Zhihong Liang,Tingting Shi,Ke Chen,Pengyi Liu,Fangyan Xie,Jian Chen,Jianbin Xu,Qiulan Chen,Weiguang Xie
VO2 particles with a reduced size enable the optimization of its metal–insulator transition (MIT) temperature and hysteresis width. The accurate modulation of particle size and the underlying mechanism of transition behavior remains a critical issue. In this study, the annealing process of a V2O5 precursor film was systematically controlled with the guidance of the V–O phase diagram. The film undergoes a synergistic solid-state dewetting and pyrolysis process in the first step to form dispersed VO2 particles, and then a crystallization process to achieve the preferred orientation, which allows fine control of the particle size and crystallinity by thickness control of the precursor film. Then, the MIT behavior of VO2 particles with controlled sizes from 220 nm to 1.64 μm was systematically investigated. With decreasing size, the MIT temperature decreases and then increases with enlarged hysteresis. A minimum MIT temperature of 41 °C without hysteresis was realized. Size dependent crystallinity, strain and defect analyses showed that compressive stress dominates the MIT behavior of larger sized particles, while surface tensile stress and surface defect effects become prominent in smaller sized particles. This work provides a feasible strategy to control the size effect of dispersed VO2 particle films and deepen our understanding on the MIT behavior in single domains.
研究领域:
材料科学
·
凝聚态物理
·
纳米科技
✓ 已验证
DOI
高影响因子
JOURNAL OF APPLIED POLYMER SCIENCE
·
2023
·Vol. 140
·期 35
·e54359
·
IF 3
Changhai Zhang,Zeyang Liu,Tiandong Zhang,Xubin Wang,Chao Yin,Xianli Liu,Qingguo Chi
The packaging insulation material was a crucial component to guarantee the stable and safe operation of electronic devices. Epoxy resin, one of the most popular packaging materials, was widely used as an electronic packaging material because of its good corrosion resistance and electrical insulation, low price, and easy processing and molding. However, the unsatisfied heat resistance cannot meet the requirements of the rapid development of third-generation power semiconductors, so it was meaningful to modify the epoxy resin with both excellent heat resistance and insulation. In this paper, tetrafunctional epoxy resin AG70 and phenolic epoxy resin F51 was blended in different proportions to combine their individual advantages, and the microstructure and electrical/thermal properties of epoxy resin blends had been systematically studied. The results showed that with the increase of blending ratio of AG70 with F51, both high glass transition temperature of 213.3°C and electric breakdown of 206.1 kV/mm were achieved when the blending ratio was 5:5, displaying excellent overall performances and exhibiting great application potential in electronic and microelectronic industries.
研究领域:
材料科学
·
电子工程
✓ 已验证
产品关联
DOI
高影响因子
COMPOSITES PART A-APPLIED SCIENCE AND MANUFACTURING
·
2022
·
IF 9.463
He Huang,Changqing Hong,Xiangyu Jin,Can Wu,Wei Wang,Hebing Wang,Yiwu Pan,Shiqi Wu,Xiaojie Yan,Wenbo Han,Xinghong Zhang
Aerogels still draw enormous interests of researchers to address the thermal insulating solutions due to environmental and energy challenges. To design and obtain lightweight organic aerogels with flexibility, thermal insulation, and hydrophobicity is one of the future directions. Herein, taking advantage of a 3D silicone framework as the backbone, a set of flexible phenolic aerogels with hierarchical architectures were fabricated by a facile one-pot and ambient pressure drying strategy. The intriguing microstructure afforded the aerogel composites multiple remarkble properties: highly-flexibility with high cyclic compressibility (70 % strain) and 1000 cycles of compression without collapse (40 % strain); excellent thermal insulating performace (insulate 126 °C at 200 °C with a thickness of 10 mm); instantaneous flame retardancy within 2 min; impressive hydrophobicity with high water contact angle of 148.5° and low sliding angle less than 6°. These integrited merits enable the composite aerogels to perform effectively in thermal management applications for long-term.
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
危险品化学品经营许可证（带存储）