This work addresses two major challenges in 3D printed ceramic composites: inadequate ceramic matrix infiltration in fiber bundles and the lack of optimized fiber-matrix interfaces. We developed a breakthrough fabrica...
详细信息
Nafion/Silicon oxide composite membranes were produced via in situ sol-gel reaction of tetraethylorthosilicate （TEOS） in Nafion membranes. The physicochemical properties of the membranes were studied by FT-IR,TG-DSC...
详细信息
Nafion/Silicon oxide composite membranes were produced via in situ sol-gel reaction of tetraethylorthosilicate （TEOS） in Nafion membranes. The physicochemical properties of the membranes were studied by FT-IR,TG-DSC and tensile strength. The results show that the silicon oxide is compatible with the Nation membrane and the thermo stability of Nation/Silicon oxide composite membrane is higher than that of Nation membrane. Furthermore, the tensile strength of Nation/Silicon oxide composite membrane is similar to that of the Nation membrane. The proton conductivity of Nation/Silicon oxide composite membrane is higher than that of Nation membrane. When the Nation/Silicon oxide composite membrane was employed as an electrolyte in H2/O2 PEMFC, a higher current density value （1 000 mA/cm^2 at 0.38 V） than that of the Nafion1135 membrane （100 mA/cm^2 at 0.04 V） was obtained at 110 ℃.
Various parameters in spark plasma sintering（SPS）,such as sintering temperature,holding time,heating rate,and pressure,were adopted to investigate their effects on the densification of pure SnO2 *** obtained experim...
详细信息
Various parameters in spark plasma sintering（SPS）,such as sintering temperature,holding time,heating rate,and pressure,were adopted to investigate their effects on the densification of pure SnO2 *** obtained experimental data show that the SPS process enhances *** high-density undoped SnO2 ceramics （96.6% of theoretical） was obtained at much lower temperature （1000℃）,within a much shorter time,compared to the conventional sintering *** high-density undoped SnO2 ceramics （96.6% of theoretical） were obtained by SPS,under the condition of temperature：1000℃,pressure：40MPa,heating-rate：200℃/min,and holding time：3min
Flame retardant epoxy resins were prepared by a simple mixed method using ammonium aluminum carbonate hydroxy hydrate （AACHH） as a halogen-free flame retardant. The prepared samples were characterized by X-ray diffr...
详细信息
Flame retardant epoxy resins were prepared by a simple mixed method using ammonium aluminum carbonate hydroxy hydrate （AACHH） as a halogen-free flame retardant. The prepared samples were characterized by X-ray diffraction, thermogravimetric and differential scanning calorimetry, scanning electron microscope and limiting oxygen index（LOI） experiments. Effects of AACHH content on LOI of epoxy resins/AACHH composite and flame retardant mechanism were investigated and discussed. Results show that AACHH exhibites excellent flame-retardant properties in epoxy resin（EP）. When the content of AACHH was 47.4%, the LOI of EP reached 32.2%. Moreover, the initial and terminal decomposition temperature of EP increased by 48 ℃ and 40 ℃, respectively. The flame retarded mechanism of AACHH is due to the synergic flame retardant effects of diluting, cooling, decomposition resisting and obstructing.
Here, a new idea was proposed for template-free synthesis of hierarchical m-ZrO2 nanorods and ＂their＂ possible formation mechanism based on a series of chemical reactions by simple hydrothermal method. The tradition...
详细信息
Here, a new idea was proposed for template-free synthesis of hierarchical m-ZrO2 nanorods and ＂their＂ possible formation mechanism based on a series of chemical reactions by simple hydrothermal method. The traditional preparation methods of hierarchical ZrO2 nanorods involved inexpensive equipment, complicated process, and high production cost. The as-synthesized products composed of many nanorods with 180-200 nm in diameter and 5-7 μm in length. The fi nal product after annealing involved hierarchical monoclinic ZrO2（m-ZrO2） nanorods, namely, the big nanorod was made up of many small nanorods with 40-50 nm in diameter and 500-600 nm in length. The experimental results were useful in understanding the chemical properties of ZrB2 and ZrO2 and the design of the derivatives for m-ZrO2 nanomaterials.
A series of samples of hexagonal boron nitride-aluminum nitride ceramic composites with different amounts of CaF2 as sintering aid were prepared by spark plasma sintered at 1700-1850 ℃ for 5 *** addition of CaF2 effe...
详细信息
A series of samples of hexagonal boron nitride-aluminum nitride ceramic composites with different amounts of CaF2 as sintering aid were prepared by spark plasma sintered at 1700-1850 ℃ for 5 *** addition of CaF2 effectively lowered the sintering temperature and promoted the densification of AlN-BN *** the increase of sintering temperature,the density increased,and the contiguity of AlN grains enhanced in AlN-BN *** conductivity of AlN-BN composites increased with the increase in CaF2 content and sintering temperature,and there is a maximum value of 78.6 W·m^-1·K^-1 when the sample with 3wt% CaF2 sintered at 1800 ℃.
A rapid-heating method in the absence of electric/magnetic field was achieved by introducing a self-propagating-combustion （SHS） as heating source. The effect of heating rate on the alumina grain growth was explored...
详细信息
A rapid-heating method in the absence of electric/magnetic field was achieved by introducing a self-propagating-combustion （SHS） as heating source. The effect of heating rate on the alumina grain growth was explored based on this rapid-heating method. Comparing with the alumina prepared by two different heating ratios （greater than 1 000 ℃/min in SItS and about 50 ℃/min in common pressureless sintering furnace）, it was revealed that the rapid heating could promote the grain growth greatly without pressure during sintering. However, if a pressure was applied simultaneously, the grain growth would be almost completely restrained. Since these observations are quite different from the expectation, a new grain growth model was proposed.
A series of new microwave dielectric ceramics Ba3-nLa1+nTinNb3-nO12 (n=0,1,2) were prepared in the BaO-La2O3-TiO2-Nb2O5 system by high temperature solid-state reaction route. The phase and structure of the ceramics we...
详细信息
A series of new microwave dielectric ceramics Ba3-nLa1+nTinNb3-nO12 (n=0,1,2) were prepared in the BaO-La2O3-TiO2-Nb2O5 system by high temperature solid-state reaction route. The phase and structure of the ceramics were characterized by X-ray diffraction, scanning electron microscope, and microwave dielectric properties measurements. These samples were identified as single phase and adopted A4B3O12-type cation-deficient hexagonal perovskite structure, which can be described as consisting of identical perovskite-like blocks, three corner-sharing BO6 octahedra thick, separated by layers of vacant octahedral. These ceramics have high dielectric constants in the range of 48-42, high quality factors (Q×f) up to 38 000 GHz, and low temperature coefficient of resonant frequencies (τf) in the range of (-40-+6)×10-6℃-1. With increasing content of La and Ti, the dielectric constants slightly decrease butτf gradually increases.
The unsatisfactory conductivity and large volume variation severely handicap the application of SnO2in sodium-ion batteries（SIBs）. Herein, we design unique three-layer structured SnO2@C@TiO2hollow spheres to tackle ...
详细信息
The unsatisfactory conductivity and large volume variation severely handicap the application of SnO2in sodium-ion batteries（SIBs）. Herein, we design unique three-layer structured SnO2@C@TiO2hollow spheres to tackle the above-mentioned issues. The hollow cavity affords empty space to accommodate the volume variation of SnO2, while the C and TiO2protecting shells strengthen the structural integrity and enhances the electrical conductivity. As a result, the three-layer structured SnO2@C@TiO2hollow spheres demonstrate enhanced Na storage performances. The SnO2@C@TiO2manifests a reversible capacity two times to that of pristine SnO2hollow spheres. In addition, Ex situ XRD reveals highly reversible alloying and conversion reactions in SnO2@C@TiO2hollow spheres. This study suggests the introduction of a hollow cavity and robust protecting shells is a promising strategy for constructing SIB anode materials.
Lithium metal is a promising anode material owing to its very low electrochemical potential and ultrahigh specific ***,the growth of lithium dendrites could result in a short lifespan,low coulombic efficiency,and pote...
详细信息
Lithium metal is a promising anode material owing to its very low electrochemical potential and ultrahigh specific ***,the growth of lithium dendrites could result in a short lifespan,low coulombic efficiency,and potential safety hazards during the progress of lithium plating/*** factors drastically hinder its application in lithium metal *** review focuses on the use of three dimensional(3D)porous host frameworks to improve Li plating/stripping behaviors,accommodate the change in volume,and suppress or block lithium dendrite *** 3D porous frameworks,including the conductive carbon-based,metal-based,and lithiophilic inorganic-compound frameworks are introduced and summarized in *** particular functions,relative developments,and optimized strategies of various 3D porous frameworks for lithium deposition/dissolution behaviors are ***,the challenges and promising developments in the field of Li metal anodes will be discussed at the end of this review.
暂无评论