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.
Transparent Fe-doped In2O3 thin film was prepared by sol-gel method on (general) glass substrate. The structure, morphologies, transmission and magnetic properties of the sample have been characterized by X-ray diffra...
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Transparent Fe-doped In2O3 thin film was prepared by sol-gel method on (general) glass substrate. The structure, morphologies, transmission and magnetic properties of the sample have been characterized by X-ray diffraction, field emission scanning electron microscopy, UV-Vis spectroscopy and vibrating sample magnetometer. XRD result indicated that the sample was single cubic In2O3 phase. FE-SEM clearly showed that the film was homogenous and composed of refining grain with an average size of 14 nm. UV-Vis spectrum indicated that the transmittance of the film was higher than 80% in the visible light, and the Fe-doped In2O3 film arose the optical absorption spectrum red shift. VSM demonstrated the sample was (room temperature ferromagnetic.
Titanium diboride (TiB2) was hot-pressed with 5% aluminum nitride (AlN) as a sintering at different sintering temperatures (1700-1900°C). The effects of sintering temperatures on microstructure and mechanical pro...
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Titanium diboride (TiB2) was hot-pressed with 5% aluminum nitride (AlN) as a sintering at different sintering temperatures (1700-1900°C). The effects of sintering temperatures on microstructure and mechanical properties were investigated. The results showed that the composites achieved the better properties when sintered at 1800°C.
Temperature distribution in the sample and the die during the process of Spark Plasma Sintering (SPS) were studied both theoretically and experimentally. The temperature difference is inevitable in the samples in SPS....
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Temperature distribution in the sample and the die during the process of Spark Plasma Sintering (SPS) were studied both theoretically and experimentally. The temperature difference is inevitable in the samples in SPS. Under certain conditions, the difference may reach a few hundreds of degrees of centigrade. Controlling of processing parameters can decrease the temperature difference. The atom diffusion at the interfaces and necks of specimen under SPS was also investigated and compared with Hot Pressing (HP). It was found that the atom diffusion in SPS is faster than that in HP, which indicates that SPS is more efficient.
A kind of Li2O-Al2O3-SiO2 system glass-ceramics, which had a low coefficient of thermal expansion, was prepared by melting method and used as the ramp-wave generator material. On one-stage light-gas gun, the experimen...
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A kind of Li2O-Al2O3-SiO2 system glass-ceramics, which had a low coefficient of thermal expansion, was prepared by melting method and used as the ramp-wave generator material. On one-stage light-gas gun, the experimental technique for quasi-isentropic compression via the ramp-wave generator was explored. By impacting the ramp-wave generator, quasi-isentropic compression waves with an extended wave's front were produced. The quasi-isentropic loadings to LY12-A1 samples were further realized via the ramp-wave generator. The results showed that the more the thickness of the ramp-wave generator, the longer the front of the generated waves and the lower the rate of the compression. The present research offered a feasible loading means for the quasi-isentropic compression under low pressures.
A multi‐particle 2D plane strain model was used to investigate the dynamic compressive properties of ceramic particle reinforced metal matrix composites (MMCs) in this paper. Ceramic particles were simulated as circl...
A multi‐particle 2D plane strain model was used to investigate the dynamic compressive properties of ceramic particle reinforced metal matrix composites (MMCs) in this paper. Ceramic particles were simulated as circles with different diameters, which were randomly and discretely embedded in the matrix. The constitutive relationship of ceramic material was characterized by Johnson‐Holmquist (JH‐2) damage model. The matrix was assumed to be power‐law strain hardening material, coupled with power‐law strain rate hardening. The ceramic/metal interface was assumed to be perfect. The predicted stress‐strain curves by the numerical models agreed well with those of experiments and unit cell analysis formulae developed by Bao and Lin [3]. The effects of overall strain rates and ceramic volume fraction on the dynamic behavior of the composites had been investigated by this numerical model. The effect of particles' distribution on the particles' damage was also discussed. The results show that the distribution and volume fraction of the particles have obvious effect on the particles' damage.
Spark plasma sintering(SPS) prepared transparent AlN ceramics by using different-content CaF2 as sintering aids, preparing porous materials and welding of alloys were researched. SPS shows its merits which could prepa...
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Spark plasma sintering(SPS) prepared transparent AlN ceramics by using different-content CaF2 as sintering aids, preparing porous materials and welding of alloys were researched. SPS shows its merits which could prepare transparent ceramics with high transparency in short time, prepare porous materials with homogeneous and controllable hole under low temperature in short time, obtain quite strong welding junction under low welding temperature and in short soaking time, owing to its special characters.
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