Well-crystallized LiFePO4 cathode materials were synthesized by NaCl-KCl molten salt method. The effect of heating time on the structure, morphology and electrochemical properties of the materials were studied in deta...
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Well-crystallized LiFePO4 cathode materials were synthesized by NaCl-KCl molten salt method. The effect of heating time on the structure, morphology and electrochemical properties of the materials were studied in detail. Single olivine-type LiFePO4 phase was obtained, and the morphology and particle size of the powders could be controlled by changing the synthesis conditions. It was shown that LiFePO4 cathode material synthesized at 680°C for 3h with the salt content N=2 (defining the molar ratio of NaCl-KCl/LiFePO4 as N) had a narrow particle-size distribution and spherical or quasi-spherical shape. Meanwhile, the tap density of the cathode material reached the maximum of 1.501gcm-3. The charge-discharge test indicated that the initial charge and discharge specific capacity reached 138mAhg-1 and 125mAhg-1 respectively at the current density of 0.3mAcm-2.
CuIn1-xGaxSe2 (CIGS) precursor films were fabricated on Mo foils by one-step electrodeposition in water and alcohol solutions. The precursor films were annealed in Ar atmosphere at 450°C to synthesize the polycry...
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CuIn1-xGaxSe2 (CIGS) precursor films were fabricated on Mo foils by one-step electrodeposition in water and alcohol solutions. The precursor films were annealed in Ar atmosphere at 450°C to synthesize the polycrystalline thin films. The current density vs. potential curves of Cu2+, In3+, Ga3+ and Se4+ was studied by cyclic voltammetry. The compositions of CIGS, were analyzed by energy dispersive X-ray spectrum. The morphology and phase structure of films was characterized by scanning electron microscopy and X-ray diffraction, respectively.
A modification analytical model is presented for the thermal elastoplastic stresses of functionally graded materials subjected to thermal loading. The presented model follows the analytical scheme presented by Y. L. S...
A modification analytical model is presented for the thermal elastoplastic stresses of functionally graded materials subjected to thermal loading. The presented model follows the analytical scheme presented by Y. L. Shen and S. Suresh [6]. In the present model, the functionally graded materials are considered as multilayered materials. Each layer consists of metal and ceramic with different volume fraction. The ceramic layer and the FGM interlayers are considered as elastic brittle materials. The metal layer is considered as elastic‐perfectly plastic ductile materials. Closed‐form solutions for different characteristic temperature for thermal loading are presented as a function of the structure geometries and the thermomechanical properties of the materials. A main advance of the present model is that the possibility of the initial and spread of plasticity from the two sides of the ductile layers taken into account. Comparing the analytical results with the results from the finite element analysis, the thermal stresses and deformation from the present model are in good agreement with the numerical ones.
An analytical model of normal ballistic impact on the ceramic/metal gradient armor, which is based on modified Alekseevskii‐Tate equations, has been developed. The process of gradient armour impacted by the long rod ...
An analytical model of normal ballistic impact on the ceramic/metal gradient armor, which is based on modified Alekseevskii‐Tate equations, has been developed. The process of gradient armour impacted by the long rod can be divided into four stages in this model. First stage is projectile's mass erosion or flowing phase, mushrooming phase and rigid phase; second one is the formation of comminuted ceramic conoid; third one is the penetration of gradient layer and last one is the penetration of metal back‐up plate. The equations of third stage have been advanced by assuming the behavior of gradient layer as rigid‐plastic and considering the effect of strain rate on the dynamic yield strength.
The effect of ceramic/metal gradient armor's components characteristic on its impact‐resistant characteristic has been investigated by a new modified Alekseevskii‐Tate equation. The following researching work is...
The effect of ceramic/metal gradient armor's components characteristic on its impact‐resistant characteristic has been investigated by a new modified Alekseevskii‐Tate equation. The following researching work is done by the former model [1]: the effect of ceramic layer on the impact‐resistant characteristic, the effect of gradient layer on the impact‐resistant characteristic and the effect of metal layer on the impact‐resistant characteristic.
Extrusion gelation freeform fabrication process is an extrusion-based freeforming technique capable of fabricating complex shaped monolithic ceramic prototypes by the sequential deposition and solidification of cerami...
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Extrusion gelation freeform fabrication process is an extrusion-based freeforming technique capable of fabricating complex shaped monolithic ceramic prototypes by the sequential deposition and solidification of ceramic suspensions from a computer aided design model. In this process, ceramic parts are produced using an extrusion nozzle suitable for extruding ceramic suspensions. In this study, the processing parameters influencing on manufacturing Al2O3 parts were discussed. Air pressure on top of suspensions, rotating speed of screw, nozzle diameter and scan speed are the main factors to influence the dimensional precision of ceramic bodies. By optimizing these processing parameters, the green bodies were fabricated with high precision. The sintered samples with homogenous microstructure and ∼97.6% relative density could be prepared by sintering of these green bodies at 1600°C for 2 hours.
The structural change in phase transition of hybrid （Cl2H25NH3）2MnCl4 was investigated. The temperature and the structures of the phase transition is investigated by thermal gravimetry （TG） and differential scanni...
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The structural change in phase transition of hybrid （Cl2H25NH3）2MnCl4 was investigated. The temperature and the structures of the phase transition is investigated by thermal gravimetry （TG） and differential scanning calorimetry （DSC）, infrared spectrum （IR） and X-ray diffraction （XRD）. The results suggest that the phase transition is reversible and the structural change arises from the conformation change of the organic chain. The interlayer distance increases when the hybrid transforms from low temperature phase to high temperature phase. This is explained by the diffusion of gauche-bond along the organic chains and they move away from each other when the phase transition occurs. Combining the experimental data with theoretical calculation, we propose that organic chain of the hybrid in high temperature phase is the conformation of gauche-bond alternating with trans bond （noted as GTG＇TGTG＇TGTG＇T）.
Two phosphonic acids: dodecylamine-N, N-dimethylenephosphonic acid (DDPA) and dodecylphosphonic acid (DPA), were used to modify zirconia stationary phase in this paper. The result of FTIR and element analysis indicate...
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Two phosphonic acids: dodecylamine-N, N-dimethylenephosphonic acid (DDPA) and dodecylphosphonic acid (DPA), were used to modify zirconia stationary phase in this paper. The result of FTIR and element analysis indicated that DPA adsorbed on zirconia with Lewis acid-base interaction;however, DDPA adsorbed mainly with chelating effect. Apart from the hydrophobicity, DDPA-ZrO2 had cation-exchange and anion-repellent interaction which was useful for the separation of polar compounds.
It is important to prepare plastic iron powders coating with silicon in order to roll the 6.5% Si-Fe directly to form the composite sheet. MA (Mechanical Alloying) was applied in this paper to fabricate the coating po...
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It is important to prepare plastic iron powders coating with silicon in order to roll the 6.5% Si-Fe directly to form the composite sheet. MA (Mechanical Alloying) was applied in this paper to fabricate the coating powders. The results were analyzed by EPMA and XRD to estimate the powder properties under different MA condition. The optimum MA condition was found. The prepared composite powders have the potential of plastic deformation.
Si3N4 ceramics were prepared by aligning the α-Si3N4 whisker in the substrate via tape casting and hot-press sintering. The phases and microstructure of the ceramics were studied by X-ray diffraction and scanning ele...
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Si3N4 ceramics were prepared by aligning the α-Si3N4 whisker in the substrate via tape casting and hot-press sintering. The phases and microstructure of the ceramics were studied by X-ray diffraction and scanning electron microscopy. The effects of tape casting on the distribution of α-Si3N4 whiskers in the substrate and the sintering conditions on the microstructure of the sintered samples were discussed. The results show that the tape casting and hot-press sintering can make the whiskers align in the substrate;the densities of the sintered samples increase with the increase of temperature. The Si3N4 ceramics with added α-Si3N4 of 10.6% (in mass) and sintered at 1500°C have higher fracture toughness of 9.24 MPa·m1/2 and Vickers hardness (Hv) of 15.74 GPa. The ceramic with rod-like grains of β-Si3N4 phase transformed by α-Si3N4 phase sintered at 1600°C has better the mechanical properties, and the fracture toughness and Hv are 10.26 MPa·m1/2 and 16.56 GPa, respectively.
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