INTERNATIONAL JOURNAL OF BIOLOGICAL MACROMOLECULES
·
2024
·
IF 7.7
Xue Ma,Xuefei Chen,Xiaohua Wang,Xiaohua Yang,Zengwen Yao,Houyong Yu,Yunyun Zhang
Polyamide 66 (PA66) has garnered significant attention due to its exceptional properties; unfortunately, its flammability is challenging. Adding flame retardants (FRs) is a primary approach to enhance PA66 flame retardancy. This study developed a highly flame-retardant PA66 composite film by adding corn-like functional nanohybrids (CNC/Al 2 O 3 ). Interestingly, CNC/Al 2 O 3 nanohybrids not only formed hydrogen bond interactions with PA66 but also improved crystallization properties as heterogeneous nucleating agents, resulting in the excellent mechanical properties of PA66 composite film. Remarkably, the incorporation of 3 wt% CNC/Al 2 O 3 nanohybrids into PA66 matrix contributed to increasing the LOI to 28.5 %. The pHRR, THR, and TSR were reduced obviously by 55.7 %, 15.3 %, and 65.2 %, respectively. The excellent flame retardancy of PA66 composite film was attributed to the forming of a compact carbon layer catalyzed by the CNC/Al 2 O 3 nanohybrids. Besides, the homogeneous distribution of CNC/Al 2 O 3 nanohybrids endowed the composite film with excellent heat insulation, and the heat insulation rate was up to 31.9 %. Thus, such PA66 composite films with excellent flame retardancy, heat insulation, and mechanical properties could meet the broader application requirements.
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DOI
PubMed
高影响因子
INTERNATIONAL JOURNAL OF REFRACTORY METALS & HARD MATERIALS
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2024
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IF 4.2
Xiao-Chun Deng,Guo-Hua Zhang
Ultra-high toughness and ultra-high hardness WC-10Co- x Al 2 O 3 cemented carbides were successfully prepared by vacuum liquid phase sintering (VS) and spark plasma sintering (SPS) using ultrafine WC and commercial Co powders as raw materials, respectively. The effects of nano-Al 2 O 3 content and sintering process on the relative density, average grain size, microstructure and mechanical properties of WC-10Co alloys were investigated. The results showed that the densification degree of the samples decreased with the increase of Al 2 O 3 content. In addition, the relative densities of the samples prepared by SPS were lower than those of the samples prepared by VS. For the samples prepared by VS, the average grain size increased first and then decreased as the Al 2 O 3 content increased from 3 wt% to 9 wt%, and the percentage of coarse grain showed the same trend. When the addition of Al 2 O 3 was 6 wt%, the average grain size reached the maximum value of 1.39 ± 1.03 μm. Meanwhile, the sample with 6 wt% Al 2 O 3 had a typical inhomogeneous dual-grain structure, and the percentages of fine grain (< 1 μm) and coarse grain (> 1 μm) were about 50%, which displayed the highest fracture toughness of 18.59 MPa·m 1/2 . The dual-grain structure not only improved the toughness, but also compensated the loss of hardness. However, for the samples prepared by SPS, with the increase of Al 2 O 3 content, the average grain size of WC decreased, while both hardness and toughness were continuously improved. When the Al 2 O 3 content increased to 9 wt%, the grain size reached the minimum value of 0.25 ± 0.08 μm, and meanwhile, the hardness and toughness reached the maximum value of 19.69 GPa and 12.29 MPa·m 1/2 , respectively. Moreover, as the Al 2 O 3 content increased, the transverse rupture strength (TRS) of the samples prepared by VS increased first and then decreased, and the TRS of sample with 3 wt% Al 2 O 3 reached the maximum value of 1410 MPa. However, the TRS of the sample prepared by SPS showed a decreasing trend.
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高影响因子
Journal of Bionic Engineering
·
2024
·Vol. 21
·期 3
·1360-1374
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IF 4.9
Liu Weilan,Li Kunlong,Shen Yizhou,Zhao Huanyu,Ni Yaru,Cai Zeyu,Zhao Lingfeng,Wang Zhen
Superhydrophobic coatings with high non-wetting properties are widely applied in anti-icing applications. However, the micro-nanostructures on the surfaces of superhydrophobic coatings are fragile under external forces, resulting in reduced durability. Therefore, mechanical strength and durability play a crucial role in the utilization of superhydrophobic materials. In this study, we employed a two-step spraying method to fabricate superhydrophobic FEVE-based coatings with exceptional mechanical durability, utilizing fluorinated TiO 2 nanoparticles and fluorinated Al 2 O 3 microwhiskers as the fillers. The composite coating exhibited commendable non-wetting properties, displaying a contact angle of 164.84° and a sliding angle of 4.3°. On this basis, the stability of coatings was significantly improved due to the interlocking effect of Al 2 O 3 whiskers. After 500 tape peeling cycles, 500 sandpaper abrasion tests, and 50 kg falling sand impact tests, the coatings retained superhydrophobicity, exhibiting excellent durability and application capability. Notably, the ice adhesion strength on the coatings was measured at only 65.4 kPa, while the icing delay time reached 271.8 s at -15 °C. In addition, throughout 500 freezing/melting cycles, statistical analysis revealed that the superhydrophobic coatings exhibited a freezing initiation temperature as low as -17.25 °C.
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高影响因子
CERAMICS INTERNATIONAL
·
2024
·
IF 5.1
Mengchuan Li,Tongsheng Zhang,Rensheng Li
The thermodynamic data of rare earth-containing systems are crucial for the development and application of permanent magnets, optoelectronic materials, high-temperature superconducting materials, and catalysts. In this study, the equilibrium phase compositions of the CaO-Ce 2 O 3 -SiO 2 -(5∼25 wt%) Al 2 O 3 system at 1873 K were investigated through high-temperature equilibrium experiments. The equilibrium phase compositions at 1873 K were determined using SEM, XRD, and EPMA, leading to the construction of isothermal sections. For the CaO-Ce 2 O 3 -SiO 2 -5 wt% Al 2 O 3 system, the isothermal cross-section diagram revealed a liquid phase region, four distinct two-phase equilibria, and two different three-phase equilibria. As the Al 2 O 3 content increased to 25 wt%, the isothermal cross-section diagram showed a liquid phase region, five different two-phase equilibria, and three distinct three-phase equilibria. The experimental results provide valuable insights for further research on the practical applications of cerium-containing rare earths in various fields.
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高影响因子
Journal of Environmental Chemical Engineering
·
2025
·
IF 7.2
Yiwei Sun,Xiaoli Wei,Fangcao Liu,Bing Liu,Jiaming Zhao,Yubao Bi,Wenfeng Han
Developing effective techniques to produce and stabilize highly active metastable F-Al-O species in HFCs dehydrofluorination system without being over-fluorinated to Al-F is a major challenge. Herein, we report a new strategy for the formation and stabilization of metastable species. Using NaH 2 PO 4 as a P source, phosphoric acid groups are modified to the surface of Al 2 O 3 leading to the fabrication of AlPO 4 /Al 2 O 3 interface. P and Al 2 O 3 bond to form Al-O-P structure at the interface and stabilize F-Al-O in the dehydrofluorination system. Further studies show that AlPO 4 /Al 2 O 3 interface increase the oxygen vacancy content of catalyst and accelerate the conversion of HFC-152a on the catalyst surface. Meanwhile, AlPO 4 /Al 2 O 3 interface improves the surface acidity of Al 2 O 3 , endue a large number of Lewis weak acid sites, reducing the carbon accumulation of catalyst, and improving the stability of catalyst. The activity test showed that AlPO 4 /Al 2 O 3 interface shows high catalytic performance (74.2 %) and excellent stability (50 h) for 1,1-difluoroethane dehydrogenation compared with Al 2 O 3 (30 % and low stability) without P modification.
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高影响因子
CHEMICAL ENGINEERING JOURNAL
·
2024
·
IF 13.3
Junpeng Jiang,Liwen Yan,Jiangtao Li,Yunjia Xue,Chensi Zhang,Xiaoxia Hu,Anran Guo,Haiyan Du,Jiachen Liu
Owing to tunable dielectric properties, light weight and high porosity, polymer-derived SiBCN ceramic aerogels possess significant application prospects in electromagnetic wave (EMW) absorption and thermal insulation. However, due to inadequate oxidation resistance, the structural collapse and performance deterioration of SiBCN aerogels will easily occur in high-temperature aerobic environments, limiting their application. Herein, to address this issue, a novel and straightforward strategy based on typical polymer-derived-ceramic (PDC) aerogel method and impregnation with boehmite sol was proposed for synthesizing SiBCN/Al 2 O 3 composite ceramic aerogels. The microstructure, phase composition, thermal insulation, oxidation resistance and EMW absorption properties of SiBCN/Al 2 O 3 ceramic aerogels were investigated. The resulting SiBCN/Al 2 O 3 composite aerogel demonstrates superior high-temperature structural stability, exhibiting an ultra-low linear shrinkage of only 6.5 % following heat treatment at 1200 °C for 2 h in air. Additionally, the composite aerogel shows a low thermal conductivity of 0.039 W/mK and a low density of 0.112 g/cm 3 . The SiBCN/Al 2 O 3 composite aerogel, composed of dielectric SiBCN, conductive free carbon, and insulating alumina, demonstrates outstanding EMW absorption properties with a minimum reflection loss of −48.6 dB and an effective bandwidth of 5.8 GHz. The enhanced microwave absorption performance is mainly attributed to the improved impedance matching, multiple reflection, and enhanced interfacial polarization resulting from the introduction of Al 2 O 3 . Given prominent oxidation resistance, thermal insulation and EMW absorption properties, the SiBCN/Al 2 O 3 composite aerogel paves the way for developing microwave absorption and thermal insulation integrated material in high-speed vehicles.
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高影响因子
ENERGY & FUELS
·
2024
·
IF 5.2
Zhiyuan Kong,Sibao Liu,Hongwang Liu,Guozhu Liu
Endothermic hydrocarbon fuel is the most utilized coolant in regenerative cooling technology for the high-speed aircraft, but it is challenged by the limited heat sink and severe coke deposition. In this study, we propose liquid ammonia as a promising carbon-free fuel with high heat sink for advanced vehicles or aircrafts. The chemical heat sink originates from the endothermic decomposition reaction of ammonia. A series of Ru/CeO2–Al2O3 catalytic coatings were fabricated on stainless-steel tubes using the washcoating method to catalyze the ammonia decomposition reaction and enhance chemical heat sink. The catalytic performance of these Ru/CeO2–Al2O3 coatings for ammonia decomposition was evaluated using an electrically heated tubular reactor. With the Ru/CeO2–Al2O3 coatings of 19 μm, ammonia conversion reaches up to 65%, and a remarkable high heat sink of 5.9 MJ/kg was achieved at 800 °C and 5 MPa. This value is ca. 68% higher than that of the typical hydrocarbon fuel JP-7. This work shows that liquid ammonia can serve as a novel generation high heat sink fuel for advanced engines and aircrafts.
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高影响因子
CERAMICS INTERNATIONAL
·
2024
·
IF 5.1
Ju Cheng,Lei Zhang,Weigui Fu,Zihan An,Meixiu Sun,Yiping Zhao,Li Chen
Gelatin, a natural protein, is extensively used in the food, pharmaceutical, and cosmetics industries. However, purifying gelatin to meet the specific requirements of various industries remains a considerable challenge. Ceramic membrane separation technology, renowned for its high permeability, excellent anti-fouling properties, and long lifespan, has been widely applied in the food, biotechnology, and water purification industries. In this study, a sol-gel method was employed to fabricate a gradient multilayer TiO 2 -modified coating on the surface of an α-Al 2 O 3 porous ceramic membrane. The viscosity of the TiO 2 sols was adjusted by varying the concentrations of polyethylene glycol (PEG 2000) and aging times. The results indicated that coating the C-P5^5 composite membrane with a sol containing 5 wt% PEG, aged for different durations (2, 5, 10, 15, and 18 d), effectively reduced the weight-average molecular weight ( M w ) of the permeate from the feed solution of 52.4 kDa–11.9 kDa. However, the C-P10^5 composite membrane, with a 10 wt% PEG content and aged for the same durations, yielded a permeate gelatin M w of 13.6 kDa. The composite membrane with excellent anti-fouling and photocatalytic self-cleaning properties holds promise for innovative applications in gelatin purification and bio-separation processes.
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高影响因子
JOURNAL OF THE ENERGY INSTITUTE
·
2024
·
IF 5.6
Xueyu Zan,Shiqi Tao,Chaoyu Zhang,Yixiao Wu,Yongjun Liu,Wei Huang
Direct conversion of methane and carbon dioxide into acetic acid is a dream way to address the two greenhouse gases, but is challenged by their chemical inertness. Cu and Pd are promising candidates both in CH 4 and CO 2 activation as well as the subsequent C-C coupling reactions at low temperature. Herein, we report that acetic acid can be produced by the direct coupling of CH 4 and CO 2 in the presence of H 2 O 2 over Cu-Pd/Al 2 O 3 catalysts at 50 °C. Results show that the acetic acid yield reaches 48.1 μmol·g cat −1 ·h −1 on the optimized reaction condition over Cu 3.8 -Pd 1.6 /Al 2 O 3 catalyst, which is higher than that of either mono-Cu or mono-Pd catalyst. Extensive characterization indicates the higher activity of Cu 3.8 -Pd 1.6 /Al 2 O 3 catalyst is attributed to the strong synergistic effect between Cu and Pd, which results in the formation of CuPdO 2 phase, and thus promoting the electron transfer from Cu to Pd. DRIFTS experiments reveal that acetic acid is produced by the coupling of CH 3 * and COOH* over CuPdO 2 active sites via Langmuir-Hinshelwood mechanism, where CH 3 * is originated from CH 4 dehydrogenation step, and COOH* may formed by the activation of CO 2 by H 2 O 2 . This study provides a new approach for the co-conversion of CH 4 and CO 2 into acetic acid at low temperature.
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高影响因子
CERAMICS INTERNATIONAL
·
2024
·
IF 5.1
Naiqiang Wang,Xiaoqing Si,Baiqi Zhang,Jianwei Gao,Mingsheng Li,Tong Lin,Rui Li,Chun Li,Junlei Qi,Jian Cao
A novel sintered-joining of Al 2 O 3 and AlN is achieved for the first time using micro-Ag particle interlayers in air. In comparison with reactive air brazing , this method addresses the issue of reduced strength caused by air holes in brazed joints . Also, this sintered-joining method can be performed at a lower temperature (920 °C), improving the joint strength by relieving the residual stresses. The sintering effect of micro-Ag particles and their high density of dislocations promote the recovery and recrystallization of the Ag interlayer, as well as the interdiffusion of Ag and ceramic. Ag–O clusters formed at the interface can be embedded into oxygen vacancies on the ceramic surface, playing a key role in interfacial joining. By optimizing joining temperature, assembly pressure and holding time, a maximum joint shear strength of 85.2 MPa is achieved at 920 °C for 30 min with an assembly pressure of 1 MPa. This study successfully prepares Al 2 O 3 /AlN joints with excellent mechanical properties, providing a reliable foundation for the fabrication of power integrated circuits with efficient operation.
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高影响因子
Case Studies in Thermal Engineering
·
2024
·
IF 6.4
Junsheng Hou,Junjie Wu,Xiong Zhao,Li Ma,Lei Huang,Yinan Qiu,Dongyu Li,Zihan Ding,Zhenzhen Chen,Jinjia Wei,Nanjing Hao
Integrating microchannel flow boiling heat transfer with nanofluids is an effective method for cooling electronic devices. However, traditional methods have significant limitations in achieving facile synthesis of nanofluids with desirable properties. In this study, we propose a straightforward synthesis strategy using microfluidic reactors, which enables continuous and high-throughout synthesis of Al 2 O 3 nanofluids with high purity and long-term stability. These nanofluids were found to enhance boiling heat transfer performance by delaying bubbles coalescence, increasing surface nucleation sites, improving the nucleation rate, and enhancing wettability by observation of the bubble behavior. Specifically, the critical heat flux (CHF) and corresponding heat transfer coefficient (HTC) are increased by a maximum of 32 % and 26 %, respectively, with negligible change in pressure drop. Moreover, the heat transfer performance deteriorates with increasing concentration of alumina nanofluids. These findings not only provide guidance of microchannel flow boiling with nanofluids, but also present valuable insights for the application of nanofluids in two-phase cooling systems for electronic devices.
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高影响因子
FUEL
·
2024
·
IF 6.7
Cheng Wang,Fengsheng Zhan,Shan Wang,Yi Wei,Jianbing Ji
Methane pyrolysis is a promising sustainable technology for CO 2 -free hydrogen production. However, the development of stable methods for methane pyrolysis to produce hydrogen at lower temperatures has presented significant challenges. This study presents a reaction system that combines molten carbonate with Ni/Al 2 O 3 catalyst and investigates methane pyrolysis using this system in a bubble-cap reactor. Remarkably, this system exhibited a low activation energy of 145.8 kJ per mole, enabling the achievement of a methane conversion of 92.5 % at 580 °C by employing a double-layer bubble cap tray configuration. Furthermore, the system showcases sustained activity for a duration of up to 72 h.
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高影响因子
危险品化学品经营许可证（带存储）