COMBUSTION AND FLAME
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2024
·
IF 5.8
Yuxiang Li,Kejuan Meng,Momang Tian,Lei Zhang,Xiaoxia Ma,Kaili Zhang
Metastable intermolecular composites (MICs) typically use Al as fuel and transition metal oxides as oxidizers , while their reactivities are hindered by the inert Al 2 O 3 passivation layer on the surface of Al particles . Recently, transition metal fluorides have emerged as novel fluorine-containing oxidizers for promoting the reactivity of metal fuels through interfacial fluorination of oxide layer . In this work, nanosized CoF 2 and Co 3 O 4 were prepared through pyrolysis of CoF 2 ·4H 2 O precursor using different calcination conditions. To investigate the function of CoF 2 in reaction and the influence of CoF 2 content on reactive performances, a series of MICs composed of n-Al, Co 3 O 4 , and CoF 2 were prepared through ultrasonic dispersion method. Thermal analysis indicated that Al/CoF 2 composite had significantly higher specific heat release (2.30 kJ/g) than that of Al/Co 3 O 4 composite (1.45 kJ/g), and CoF 2 facilitated the occurrence of exothermic reaction at a relatively lower temperature. AlF 3 was found as main reaction products of Al/CoF 2 at 650 °C, and AlF 3 sublimes at the temperature above 850 °C. Although the pressure output and flame intensity of Al/CoF 2 composite is lower than that of Al/Co 3 O 4 composite, hybrid Al/Co 3 O 4 /CoF 2 composites with 20 %–35 % CoF 2 showed significantly enhanced energetic performances compared with sole Al/Co 3 O 4 , suggesting that CoF 2 can function as an effective reaction modifier.
研究领域:
材料科学
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含能材料
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燃烧化学
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纳米材料
✓ 已验证
DOI
高影响因子
APPLIED CLAY SCIENCE
·
2017
·
IF 3.101
Ning Mao,Chun Hui Zhou,John Keeling,Saverio Fiore,Hao Zhang,Liang Chen,Gui Chen Jin,Ting Ting Zhu,Dong Shen Tong,Wei Hua Yu
Dolomite is a widespread carbonate mineral that has been investigated extensively over the past two centuries. Despite the high level of investigation, aspects of the environmental conditions of crystallization, diagenesis and dissolution remain elusive and the transformation of dolomite into other value-added products is still challenging. This work shows a novel, cleaner method to dissolve dolomite by taking advantage of the acidity from the hydrolysis of Lewis acid AlCl 3 and as such the mineral can be efficiently converted into Ca-Mg-Al layered double hydroxide (LDH). The dolomite and the resulting Ca-Mg-Al LDH samples were characterized by powder X-ray diffraction (XRD), Fourier transformed infrared spectroscopy (FT-IR), thermogravimetric analysis (TG), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The composition of the products was measured by energy dispersive spectrometer-mapping (EDS-mapping), X-ray fluorescence (XRF) and atomic absorption spectroscopy (AAS). Particle sizes of the products were measured by a dynamic light scattering method. It is documented, for the first time, that dissolution of dolomite in AlCl 3 aqueous solution is facilitated by hydrothermal treatment . Well-crystallized Ca-Mg-Al LDH crystals are achieved under (Ca + Mg): Al molar ratio = 1:1, pH = 10.5 via a simple co-precipitation method. The maximum utilization efficiencies of Ca 2+ , Mg 2+ from dolomite to LDH are 36.3% and 95.5%, respectively. The possible mechanisms of LDH formation were: 1) the dolomite dissolved in the strong acid solution due to the hydrolysis of AlCl 3 and thus provided Ca 2+ and Mg 2+ ; 2) with addition of NaOH, Al 3+ cations precipitated to form Al(OH) 3 (at 8.3 ≤ pH ≤ 9.3) and then part of the Al(OH) 3 reacted with Ca 2+ and Mg 2+ to form the Ca-Mg-Al LDH; 3) at pH = 10.5, the Al(OH) 3 was transformed as [AlO(OH)] and meanwhile Ca 2+ , Mg 2+ and Al 3+ took part in the formation of Ca-Mg-Al LDH; 4) when pH = 10.6, [AlO(OH)] reacted with NaOH to dissolve into [Al(OH) 4 ]− and the [Al(OH) 4 ]− finally co-precipitated with Ca 2+ and Mg 2+ to form the Ca-Mg-Al LDH during heating for drying.
研究领域:
材料科学
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矿物加工
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无机化学
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环境地球化学
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湿法冶金
✓ 已验证
DOI
高影响因子
PROPELLANTS EXPLOSIVES PYROTECHNICS
·
2023
·Vol. 48
·期 3
·e202200313
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IF 1.8
Xiang-Dong Meng,Shui-Zhou Cai
In this study, the Al-B-Mo alloy powders with a boron content of 7 wt % and Molybdenum content of 0.5–3 wt % were prepared by the close-coupled gas atomization. The powder morphology, phase composition, oxidation, and exothermic behavior of combustion were characterized. The results show that the addition of Mo effectively improves the energetic properties of the alloy powder, with the mass-burning enthalpy of Al-7B-1Mo reaching 31111 J/g, exceeding the theoretical mass-burning enthalpy of monolithic Al (31000 J/g). Al-7B-1Mo underwent a violent exothermic process at around 1000 °C, and the oxidation weight gain ratio and oxidation efficiency reached 46.16 % and 48.05 % respectively, an increase of 19.75 % and 21.08 % compared to Al-7B. The mesh structure formed by the AlB 2 phase on the particle surface positively promoted the particles′ thermal oxidation. Mechanical mixtures of AlB 2 /Mo and AlB 2 /MoO 3 were prepared and the catalytic promotion of the combustion of AlB 2 by Mo and MoO 3 was confirmed by thermal tests of combustion. The mechanism by which Mo/MoO 3 promotes the combustion of AlB 2 was investigated through the phase composition characterization of the composite powder after heat treatment in argon and air atmosphere. It was confirmed that MoO 3 promotes the oxidation and combustion of AlB 2 by supplying oxygen to B in AlB 2 , while Mo is first oxidized to MoO 3 , which then promotes the combustion of AlB 2 .
✓ 已验证
DOI
高影响因子
NEW JOURNAL OF CHEMISTRY
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2023
·Vol. 47
·期 29
·13993-14001
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IF 3.3
Wenhui Wu,Conger Deng,Qian Lei,Honglin Chen
ZSM-5 could be a good candidate for the catalysis of formaldehyde to trioxane (TOX) because of its appropriate and adjustable acid properties. However, the space-time yield (STYTOX) and selectivity of the TOX catalyzed by ZSM-5 zeolites are relatively low at present. [Ga, Al]-MFI zeolites containing different Ga/Al atomic ratios were used as catalysts for reaction of synthetic TOX. The structural information of the materials was illustrated by characterization through XRD, ICP-OES, XPS, SEM, BET analysis, and MAS NMR spectroscopy. And the acid properties of the materials were tested by NH3-TPD and Py-IR. The catalytic performance test showed that the STYTOX of [Ga, Al]-MFI-50 is about twice that of ZSM-50 or [Ga]-MFI-50. And the selectivity of TOX is also significantly improved compared to that with [Al]-MFI-50 and Ga-MFI-50. This is because the introduction of Ga atoms into ZSM-5 causes the Brønsted acid content to rise, resulting in STYTOX. It is worth noting that adjusting the Ga/Al atom ratio in the framework affects the B/L value of the zeolite, which leads to the optimization of the selectivity.
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产品关联
DOI
高影响因子
Journal of Materials Chemistry A
·
2023
·Vol. 11
·期 32
·17020-17026
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IF 11.9
Shiman He,Jie Wang,Xu Zhang,Weiqin Chu,Shu Zhao,Daping He,Min Zhu,Haijun Yu
Rechargeable aluminum batteries (RABs) are regarded as a promising energy storage system considering the high safety, rich abundance, and high capacity of aluminum. One of the critical challenges for RABs is the dendrite growth of Al, which arouses significant stability and safety issues. In this work, we demonstrate that a graphite coating layer can effectively protect the Al anode against dendrite growth. The Al metal batteries with graphite-coated Al anodes display lower overpotential (43 mV) and better cycling stability (400 h) than those with bare Al. Based on spike-like voltage profiles, metallic Al is found to be preferentially plated on the graphite layer rather than the Al substrate. In addition, the rough graphite coating layer with abundant interspace further regulates the plating/stripping behavior and accommodates the volume change of the Al anode. The dendrite growth of Al is significantly suppressed by graphite coating, which also favors high-performance RABs with a graphite cathode. This study sheds light on the facile and efficient suppression of Al dendrite growth toward RABs.
✓ 已验证
产品关联
DOI
高影响因子
VACUUM
·
2022
·
IF 4.11
Chaofei Bai,Shengnan Li,Desheng Yang,Jie Li,Guoping Li,Yunjun Luo
Nanothermite has attracted much attention because of the larger interface contact area between oxidizer and fuel. Usually, one of the important ways to improve the reaction and combustion performance is to make fuel contact with oxidizer more closely, so the preparation of large specific surface area oxidizer is a very effective method. Therefore, tremella NiO were prepared in ethylene glycol using nickel acetate as precursor by means of mediated self-assembly and calcination process, with a specific surface area of 310.69m 2 /g. which was an oxidant to prepare Al@NiO nanothermite by ultrasonic mixing. The thermal properties , combustion performance of Al@NiO were analyzed by differential scanning calorimetry and high-speed camera, and compared with Al/NiO nanothermite prepared by using commercially purchased Al and NiO as raw materials. Compared with Al/NiO, the heat release of Al@NiO increased by 268J/g, the activation energy decreased by 88 kJ/mol, and the combustion flame was brighter, the combustion time was shorter, and the energy release was faster. It was also found that stoichiometric ratio has significant effects on the energy output of nanothermite, and the fuel-rich formula has more prominent energy characteristics. The alcohol-thermal synthesis method adopted in this paper is also expected to be applied to other nanothermite systems.
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产品关联
DOI
高影响因子
Defence Technology
·
2022
·
IF 4.035
Yao-feng Mao,Qian-qian He,Jian Wang,Chuan-hao Xu,Jun Wang,Fu-de Nie
As a typical energetic composite, polytetrafluoroethylene (PTFE)/aluminum (Al) has been widely applied in explosives, pyrotechnics, and propellants due to its ultra-high energy density and intense exothermic reaction. In this work, the radial gradient (RG) structure of PTFE/Al cylinders with three different PTFE morphologies (200 nm and 5 μ m particles and 5 μ m fiber) and content changes are prepared by 3D printing technology. The effect of radial gradient structure on the pressure output of PTFE/Al has been studied. Compared with the morphology change of PTFE, the change of component content in the gradient structure has an obvious effect on the pressure output of the PTFE/Al cylinder. Furthermore, the relationships of the morphology, content of PTFE and the combustion reaction of the PTFE/Al cylinder reveal that the cylinder shows a more complex flame propagation process than others. These results could provide a strategy to improve the combustion and pressure output of PTFE/Al.
✓ 已验证
DOI
高影响因子
JOURNAL OF CATALYSIS
·
2022
·
IF 8.047
Minjie Xu,Xianglin Liu,Guiyao Song,Yingying Cai,Bianfang Shi,Yitao Liu,Xiaoxu Ding,Zixu Yang,Pengfei Tian,Chenxi Cao,Jing Xu
Different iron species exhibit distinct activity and selectivity in CO 2 hydrogenation reaction. Herein, by controlling calcination temperature, Fe-Al interaction in Na promoted Fe-Al catalysts has been regulated, which further leads to various compositions of iron oxide (FeO x ) and iron carbides (Fe 7 C 3 and Fe 5 C 2 ) after CO activation and CO 2 hydrogenation reaction. The phase compositions and structures of Fe-Al catalysts are carefully distinguished by multiple characterizations, including XRD, XPS, MES and TEM, and the reactivity of different phases is studied with the combination of experiments (kinetics, TP and in situ DRIFTS) and Density Functional Theory (DFT) calculations. Our FeAl350 with the highest FeC x content shows the highest CO 2 conversion of 48.2% and the lowest CO selectivity of 10.1%, and FeAl900 with the highest Fe 5 C 2 / FeC x ratio presents the highest C 5+ selectivity of 44.6%. Finally, a correlation between different compositions of iron species with the activity and selectivity of Fe-based for CO 2 hydrogenation to olefins was established.
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产品关联
DOI
高影响因子
COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS
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2022
·
IF 5.518
Ruolin Wang,Wenjuan Sun,Haisheng Han,Wei Sun,Zhao Wei,Jian Peng
The flotation separation of scheelite from fine calcite is difficult due to the larger specific surface area and higher activity with flotation collectors. The selectivity of caustic starch as the depressant is poor, due to the -OH functional group reacting with the similar Ca 2+ active sites of scheelite and calcite. In this paper, a novel structure of Al-caustic starch is prepared by the reaction of Al 3+ and caustic starch, which has a new functional group of -CH 2 -O-Al 2+ . The Al-caustic starch is an effective depressant for the fine calcite particles, contributing to the efficient flotation separation of scheelite from the fine calcite particles. All the flotation kinetics of scheelite and fine calcite is first-order uniform distribution model, and the flotation rate of calcite decreases significantly after the treatment of Al-caustic starch. The zeta potential of Al-caustic starch is much higher than that of caustic starch, and Al-caustic starch can selectively change the surface charge of fine calcite, instead of scheelite. The X-ray photoelectron spectroscopy (XPS) spectrum of Al-caustic starch appears the peak of Al atom, which chemisorb on the calcite surface and make the peak of characteristic atoms shift. Moreover, Al-caustic starch reacts with the anion of CO 3 2- on fine calcite surface, instead of cation of Ca 2+ , which obviously improves the selective adsorption on mineral surface.
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产品关联
DOI
高影响因子
JOURNAL OF ALLOYS AND COMPOUNDS
·
2022
·
IF 6.371
Chang Zhou,Yongxiao Zhou,Saiyue Liu,Lianyu Zhang,Peiyu Song,Qiang Zhang,Biyuan Ma,Gaohui Wu
Negative thermal expansion particles can compensate metal matrix composites to achieve near-zero thermal expansion materials. However, there are huge thermal residual mismatch stresses in the particles due to the thermal expansion mismatch between matrix and reinforcement. The use of hybrid reinforcement is required to solve the stress concentration problem. In this study, the hybrid Al matrix composites reinforced with ZrW 2 O 8 and SiC reinforcements (SiCp, SiCnw) were fabricated by the pressure infiltration process. The effect of SiC content on microstructure, phase composition, thermal expansion and mechanical properties were examined by a combination of XRD , SEM, thermal dilatometer and bending tests. The results showed that the high-pressure phase (γ-ZrW2O8) content of hybrid metal matrix composites decreased with increasing SiC fraction. Among them, the composites containing 61.7 vol%ZrW 2 O 8 and 3.3vol%SiCnw achieved the best performance with a bending strength of 100–150 MPa and a near-zero thermal expansion (2.0–3.0 ×10 –6 K −1 ) in a wide range of − 50–120 °C, which was attributed to the synergetic hybrid effects of SiCnw and ZrW 2 O 8 . This work opens up a new frontier for the design and preparation of lightweight zero-thermal expansion materials.
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产品关联
DOI
高影响因子
CHEMICAL ENGINEERING JOURNAL
·
2023
·
IF 15.1
Li Ren,Jian Wang,Yaofeng Mao,Jie Chen,Yongjun Deng,Xingquan Zhang,Jun Wang
Aluminum (Al) is one of the most widely used metal fuels in the fields of automotive airbags, solid propellants, explosives and pyrotechnics. Unfortunately, it is hard to meet further demand of practical applications owing to the comparatively low calorific value. Herein, graphite fluoride (CF) and boron (B) are employed to construct Al/B/CF microspheres through self-assembly in emulsion to obtain high energy density and significantly improved combustion performance resulted from synergistic reaction between Al and B reacted with fluorine. The Al/B/CF microspheres with pore structure have uniformly distribution of components and the average size range from 60 to 600 μm. Based on the experimental results, CF content and Al/B mass ratio have significant important effects on the combustion behavior and pressure output. The highest burning rate (301.74 m/s) and pressurization rate (77.78 MPa/s) are obtained for the Al/B/CF microspheres with CF content of 50 wt% and Al/B mass ratio of 3 to 1, respectively. Furthermore, the combustion reaction process of single Al/B/CF microsphere are studied for the first time to understand the synergistic reaction between high reactivity of Al and high energy of B reacted with fluorine. This work demonstrates that introducing CF and B to construct Al/B/CF microspheres is an efficient strategy to achieve high energy density and reactivity for the practical applications.
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产品关联
DOI
高影响因子
JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS
·
2021
·
IF 2.993
Guanghui Han,Rui Sui,Yongsheng Yu,Li Wang,Menggang Li,Ji Li,Hu Liu,Weiwei Yang
Ion substitution is considered to be one of the efficient approaches to improve the magnetic properties of the barium hexaferrites. In this work, we fabricated BaFe 12− x Al x O 19 ( x = 0, 1, 2, 4, 6) via a simple auto-combustion method and investigated their structures, morphologies and magnetic properties. The coercivity is greatly affected by annealing temperature and Al 3+ content. In addition, the Al 3+ substitution sites in BaFe 12− x Al x O 19 were further investigated by the Mössbauer spectroscopy and the superparamagnetic components were found in the BaFe 8 Al 4 O 19 and BaFe 6 Al 6 O 19 . The highest coercivity of 13.7 kOe was achieved in the BaFe 8 Al 4 O 19 , which increases by 168.6% compared with that of BaFe 12 O 19 . This work opens up a new and meaningful insight for the understanding of microstructure and coercivity mechanism towards the Al 3+ substituted barium hexaferrites.
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产品关联
DOI
高影响因子
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