CERAMICS INTERNATIONAL
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2019
·
IF 3.45
Qianglong He,Jingjing Xie,Aiyang Wang,Chun Liu,Tian Tian,Lanxin Hu,Chenhong Yi,Zhixiao Zhang,Hao Wang,Weimin Wang,Zhengyi Fu
B x C-TiB 2 -SiC ceramic composites were fabricated via reactive hot pressing using TiC, B, and Si as the raw materials. The phase transition process was studied by heating powder mixtures to different temperatures in combination with X-ray diffraction analysis. The stoichiometric ratio between B and C in boron carbide is variable. A series of powder mixtures containing excess boron (0 wt%, 10 wt%, 20 wt%, or 30 wt% B) were sintered, and the microstructures and mechanical properties of the composites were investigated. The results showed that the B 6.1 C-TiB 2 -SiC composite prepared from the starting powders with 30 wt% excess boron had the best comprehensive mechanical properties , with a relative density, hardness, bending strength , and fracture toughness of 98.32%, 33.2 GPa, 840 MPa, and 5.22 MPa m 1/2 , respectively. Excessive boron substitution may cause lattice distortion in boron carbide , and the boron carbide grains in this state may form a large number of twins under the compressive stress generated by the TiB 2 grains, which will affect the properties of the composites.
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MICROPOROUS AND MESOPOROUS MATERIALS
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2019
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IF 4.182
Kai Gao,Qing Wang,Xuexun Du,Qinglian Wei,Yongmin Huang
Dimethylamine (DMA), which is mostly generated in fine chemical industry, has enormously threatened the public health, therefore should be eliminated from water efficiently. Superior to any other methods to remove DMA, adsorbing it by sorbent could avoid the generation of secondary pollution. Among all the sorbents employed in this study, low Si/Al ratio Beta zeolite synthesized without organic template exhibits the highest performance of adsorbing DMA from water. When the transition-metal cations were introduced by ion-exchange, the adsorption of DMA was enhanced. Subsequently, the saturated adsorbent was heated in air condition, detection results of the off-gas indicated that nearly all of the DMA adsorbed was oxidized and negligible harmful by-product was produced. Beta zeolite adsorption coupled with catalytic oxidation could eliminate DMA efficiently and environmental friendly which has wide application prospects in waterworks.
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高影响因子
SOLID STATE SCIENCES
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2019
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IF 2.155
Jianxun Zhao,Xiangjun Zhou,Yalan Guo,Zhongmin Su,Heng Liu,Wanqiang Liu,Shang Gao
Co 0.9 Cu 0.1 Si alloy was fabricated via mechanical alloying technique. Different amount of palladium was doped into the Co 0.9 Cu 0.1 Si alloy by ball milling. The composite alloy combined the excellent electrocatalysis activity of Pd, exhibiting preferable electrochemical performance than the original alloy. The Co 0.9 Cu 0.1 Si + 5 wt% Pd composite showed a C max of 559.2 mAh/g, significantly higher than that for Co 0.9 Cu 0.1 Si (502.1 mAh/g). The cycle stability was also enhanced after Pd loading. Moreover, the effect of ball milling time on electrochemical performance for the composite alloy was also investigated. 5 wt% Pd was mixed with the Co 0.9 Cu 0.1 Si alloy at different ball milling time (0.5 h, 1 h, 2 h, 3 h and 5 h). The optimal discharge capacity, capacity retention and high-rate dischargeability were obtained under the ball milling time of 2 h. The studies on electrochemical reaction kinetics demonstrated that the addition of Pd could accelerate the charge-transfer, thus enhancing the electrochemical activity and reaction kinetics of the alloy. The results indicated that Pd loading was an effective way in enhancing the electrochemical performance of Co 0.9 Cu 0.1 Si alloy.
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CHEMISTRY OF MATERIALS
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2019
·
IF 10.159
Tongtong Yu,Shanpeng Wang,Xiang Zhang,Chenning Li,Jie Qiao,Ning Jia,Bing Han,Sheng-Qing Xia,Xutang Tao
Mid-infrared (MIR) nonlinear optical (NLO) crystals are crucial in generating MIR lasers, which are important in civilian and military applications. Compared to the extensively investigated ternary and quaternary chalcogenide NLO crystals, ternary phosphide crystals have a large nonlinearity coefficient and a wide transparency range. For instance, the well-known ternary chalcopyrite phosphide NLO crystal, ZnGeP2, possesses a large nonlinearity coefficient (deff = 75 pm/V) and a broad transmittance range of 0.75–12 μm. However, its applications in the far-infrared laser range were hindered by its strong absorption near 9 and 10–12 μm. Here, considering that Mn2+ not only makes contributions to large second-harmonic generation (SHG) response but also extends the transparency wavelength range, a new ternary chalcopyrite phosphide crystal, MnSiP2 (MSP), was rationally designed by substituting a II-site metal (Zn or Cd) for Mn in the II-Si-P2 family. In this work, the synthesis and single-crystal growth of MSP were systematically investigated. The theoretical and experimental characterizations demonstrated that MSP exhibits a good balance between strong SHG behavior (6 × AgGaS2) and large laser damage threshold (about 70 MW/cm2). Specifically, the long-wavelength MIR cutoff edge of MSP is 18.2 μm, and the outstanding terahertz (THz) transmittance covers the range of 0.4–2.0 THz, indicating the ultrabroad transparency range. This work may provide a feasible strategy and impel one to search for promising outstanding MIR NLO crystals in the ternary phosphide family.
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SEPARATION AND PURIFICATION TECHNOLOGY
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2019
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IF 5.107
Yusheng Yang,Chaoqun Lan,Yingcai Wang,Zengwu Zhao,Baowei Li
In this work, a simple and sustainable approach is proposed to recover rare earths and iron from an ultrafine NdFeB waste. Rare earths are directly recovered by one-step precipitation in hydrofluoric acid and the dissolved iron by electrodeposition. The rate constant and activation energy of the reaction of rare earth hydroxide with hydrofluoric acid are investigated to understand the kinetics of iron leaching and rare earth precipitation. The rare earth precipitation is much faster than the iron leaching, enabling the rare earths separation from iron after a complete iron dissolution. The cathodic deposits of iron were characterized by X-ray photoelectron spectrometer (XPS) and scanning electron microscope (SEM). The nano-scale FeF 2 (s) and Fe(s) were deposited on Pt electrode in hydrofluoric acid solution with pH 2.3 and pH 2.89, respectively. The reduction of Fe(III) to Fe(0) was investigated by cyclic voltammetry, chronopotentiometry and open circuit chronopotentiometry. This reduction was a quasi-reversible process which was controlled by diffusion. The temperature dependence of the diffusion coefficient was established as lnD = −9.84 − 1805.43/ T and the activation energy value of the diffusion process was calculated to be −15.01 kJ mol −1 . The relationship between the Gibbs energy of intermetallic Fe-Pt formation and the temperature was established to be Δ G = −487.53 + 0.936 T . The hydrofluoric acid after the electrodeposition could be recycled for the leaching of the ultrafine NdFeB waste again.
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JOURNAL OF THE EUROPEAN CERAMIC SOCIETY
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2019
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IF 4.029
Limeng Liu,Jozef Vleugels,Shuigen Huang,Jie Wei,Yujin Wang
TaC ceramics with 0-0.237 wt% B addition were prepared by hot pressing. The effect of B addition on the phase constitution, interfacial chemistry/bonding and mechanical properties of the TaC ceramics were investigated. Upon B addition, the elimination of O impurity and segregation of B at grain boundaries were evidenced, accompanied by an increase in bonding strength of the TaC grains, to result in a fracture mode change from intergranular to transgranular and a reduced fracture toughness. Addition of excessive B resulted in the formation of TaB 2 and C within TaC ceramics. Further, TaC-TaB 2 -SiC composites were prepared by Si addition. Coherent bonding between TaB 2 and TaC was preserved in the TaC-TaB 2 -SiC composites, and residual stresses due to thermal expansion mismatch of the different phases increased flexural strength and fracture toughness of the composites.
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Nanoscale
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2019
·Vol. 11
·期 36
·16781-16787
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IF 6.97
Na Li,Zheng Yi,Ning Lin,Yitai Qian
The application of Si-based anode materials is hindered by their extreme volume change, poor cycling stability, and low coulombic efficiency. Solving these problems generally requires a combination of strategies, such as nanostructure designing or surface coating. However, these strategies increase the difficulty of the fabrication process. Herein, a simple and one-pot replacement reaction route was designed to produce an Al2O3 layer anchored on mesoporous Si nanospheres (Si@Al2O3) by employing Al nanospheres with a naturally formed Al2O3 layer as a reducing agent and self-sacrificial template. The obtained Si@Al2O3 was mesoporous, with enough porous space to buffer the volume change and provide a fast lithium ion transfer channel. Furthermore, the coated Al2O3 layer could stabilize the structure and SEI layer of the mesoporous Si nanospheres, endowing the Si@Al2O3 nanospheres with improved initial coulombic efficiency, cycling performance and rate capability. As a result, a high capacity of 1750.2 mA h g−1 at 0.5 A g−1 after 120 cycles and 1001.7 mA h g−1 at 2 A g−1 after 500 cycles were delivered for lithium ion batteries. The good performance could be attributed to the mesoporous structure and the outer-coated Al2O3 layer.
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PubMed
高影响因子
CHEMICAL ENGINEERING JOURNAL
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2018
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IF 6.735
Hongwei Mi,Xiaodan Yang,Yongliang Li,Peixin Zhang,Lingna Sun
Due to its high specific capacity, silicon (Si) is considered as the most promising alternative anode material for high energy density lithium-ion batteries, but it suffers from dramatic volume expansion during the charge/discharge process. Fabricating yolk-shell structure is regarded as an essential way to improve the conductivity and cycle stability of Si-based anode. In this work, we proposed a “self-sacrifice template strategy” by using polyethyleneimine (PEI) to form the void space during carbonation without acid or base etching, which was different from the colloidal templates method. The yolk-shell structured silicon@void@carbon (Si@void@C) composites were synthesized to enhance cycle stability for lithium-ion batteries, which delivered a capacity of 854.1 mAh·g −1 at the current density of 0.2 A·g −1 after 200 cycles. Our work is also expected to be extended to the synthesis of other yolk-shell structured composites and the application in energy storage, catalysis, biomedicine and other fields.
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ACS Nano
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2018
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IF 13.709
Yongling An,Huifang Fei,Guifang Zeng,Lijie Ci,Shenglin Xiong,Jinkui Feng,Yitai Qian
Silicon is considered as one of the most favorable anode materials for next-generation lithium-ion batteries. Nanoporous silicon is synthesized via a green, facile, and controllable vacuum distillation method from the commercial Mg2Si alloy. Nanoporous silicon is formed by the evaporation of low boiling point Mg. In this method, the magnesium metal from the Mg2Si alloy can be recycled. The pore sizes of nanoporous silicon can be secured by adjusting the distillated temperature and time. The optimized nanoporous silicon (800 °C, 0.5 h) delivers a discharge capacity of 2034 mA h g–1 at 200 mA g–1 for 100 cycles, a cycling stability with more than 1180 mA h g–1 even after 400 cycles at 1000 mA g–1, and a rate capability of 855 mA h g–1 at 5000 mA g–1. The electrochemical properties might be ascribed to its porous structure, which may accommodate large volume change during the cycling process. These results suggest that the green, scalable, and controllable approach may offer a pathway for the commercialization of high-performance Si anodes. This method may also be extended to construct other nanoporous materials.
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JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS
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2018
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IF 3.046
Xiaoshan Yang,Xiufang Cui,Guo Jin,Jinna Liu,Yanbo Chen,Zhe Liu
Laser additive manufacturing (LAM) is a novel method for processing compositionally graded alloys and becomes increasingly important in the context of next-generation manufacturing technology. In this work, (Fe 60 Co 35 Ni 5 ) 78 Si 6 B 12 Cu 1 Mo 3 soft magnetic alloys with different laser power were designed and processed by the LAM. The magnitudes of magnetic properties were analyzed, and the relationships among composition-microstructure-magnetic properties assessed. Results show that the (Fe 60 Co 35 Ni 5 ) 78 Si 6 B 12 Cu 1 Mo 3 alloys by LAM exhibits relative uniform microstructure and comparable magnetic property compared with those conventional processed alloys. The bcc dominated microstructures exhibit a substantially higher saturation magnetization (Ms). With the increase in power, the average grain size of the alloy increased slightly and the increasing volume fraction of the Fe Si phase leaded to the enhancement of magnetization. The (Fe 60 Co 35 Ni 5 ) 78 Si 6 B 12 Cu 1 Mo 3 alloys with laser power of 3000 W exhibits the highest Ms (199 emu/g). The appearance of Fe 3 B results in coarse dendrites and high coercivity (Hc) in the multiple re-heating cycles.
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COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS
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2018
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IF 2.829
Yuting Meng,Lexin Zhang,Ruirui Xing,Hao Huang,Yuan Qu,Tifeng Jiao,Jingxin Zhou,Qiuming Peng
The fabrication of graphitized diamond covered with polypyrrole (D@G@PPy) core-shell nanocomposites has been achieved by using a superficial electrochemical polymerization and self-assembly strategy. The conductivity of the core-shell nanocomposites was influenced by polymerization time, current as well as the concentration of ions. The obtained excellent conductivity appeared with the current of 0.6 mA and the duration time of 1 h. In addition, the corresponding enhanced electrochemical performance of polypyrrole grown on graphitized diamond substrate is demonstrated compared with pristine polypyrrole. The morphologies of the obtained composites were illuminated through scanning electron microscopy (SEM) and the conductivity was demonstrated by electrochemical impedance spectroscopy (EIS). The characteristic peaks of polypyrrole and qualitative analysis of surface elements have been investigated by Raman spectra and X-ray photoelectron spectroscopy (XPS). The present research could demonstrate a new aspiration for the design and preparation of novel polypyrrole core-shell composites materials.
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CERAMICS INTERNATIONAL
·
2018
·
IF 3.057
Shi-Pan Yin,Zhao-Hui Zhang,Xing-Wang Cheng,Tie-Jian Su,Zheng-Yang Hu,Qi Song,Hao Wang
Almost fully dense B 4 C-TiB 2 -SiC composite ceramics with high flexure strength and good fracture toughness were fabricated through in-situ reaction between B 4 C, Ti 3 SiC 2 and Si using spark plasma sintering method at a relatively low temperature of 1650 °C. The intergranular and intragranular structure containing nanoparticles with different phase were introduced into the composite ceramic. The nano and micro particles in the microstructure formed a multi-scale particles reinforced structure. The refined matrix grains and the multi-scale reinforcing particles had a synergetic effect on improving the mechanical properties of the composite ceramics. As a result, B 4 C-TiB 2 -SiC composite ceramic with 30 wt% (TiB 2 + SiC) exhibits low density and optimum mechanical properties with high flexural strength of 531.2 MPa, good fracture toughness of 5.77 MPa m 1/2 and moderate micro-hardness of 28.6 GPa.
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危险品化学品经营许可证（带存储）