In this study, the sedimentation stability and rheology of a new magnetorheological fluid formulation were experimentally investigated before and after being stored for 24 months, as well as after being milled. The re...
In this study, the sedimentation stability and rheology of a new magnetorheological fluid formulation were experimentally investigated before and after being stored for 24 months, as well as after being milled. The results reveal that, after undergoing 24 months of steady storage, the off-state viscosity and field-induced yield stress of the MR fluid remained constant, and that its flowability and redispersibility were maintained. After being subjected to ball milling for 2 hours at 200 rpm and 300 rpm, the field-induced yield stress was also maintained.
The precursor of M-type barium hexaferrite with iron excess, which the nominal composition was BaFe12.4O19.6, was prepared by a so-called co-dump coprecipitation method. The crystallization behavior of the precursor u...
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The precursor of M-type barium hexaferrite with iron excess, which the nominal composition was BaFe12.4O19.6, was prepared by a so-called co-dump coprecipitation method. The crystallization behavior of the precursor under the spark plasma sintering (SPS) conditions and the magnetic properties of the SPS samples were investigated. The results show that the samples obtained at 700-850°C were composed of single-phase M-type barium hexaferrite, and that the crystallization of intermediates such as BaFe2O4 and Y-Fe2O3 did not occur. The distribution of crystal grains obviously changed with the increase of temperature;the distribution was random at 700°C and became preferential orientation when the temperature was more than 700°C. The saturation magnetization significantly increased at 700°C and remained almost constant in the range of 750°C to 850°C. This accorded with the evolution characteristics of the phase composition of the SPS samples with the increase of temperature. The coercivity first increased and then decreased with the increase of the temperature, which was attributed to the corresponding increases in the content of M-type barium ferrite and the degree of preferential orientation of crystal grains.
The carbonyl iron/Al2O3 core-shell composite particles with different morphologies of nanoshells were prepared and the influences of the Al2O3 nanoshell morphologies on the properties of the carbonyl iron/Al2O3 core-s...
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The carbonyl iron/Al2O3 core-shell composite particles with different morphologies of nanoshells were prepared and the influences of the Al2O3 nanoshell morphologies on the properties of the carbonyl iron/Al2O3 core-shell composite particles were investigated. The results show that the shell morphologies of the carbonyl iron/Al2O3 core-shell composite particles strongly depend on the species of acid and pH value. Compared to the carbonyl iron particles, the anti-oxidation property, microwave electromagnetic parameters and mechanical properties of the composite particles are significantly improved, and the particles, uniform, compact and grain-like Al2O3 nanoshells are beneficial to improving the anti-oxidation property and decreasing permittivity with the retention of permeability, while fiber-like Al2O3 nanoshells are more advantageous to improving the interface compatibility between the particles and the matrix of the polymers, resulting in obvious increase of mechanical properties of their based absorbing coatings.
Tin dioxide based ceramics doped with ZnO, Sb2O3 and ZnO-Sb2O3 were prepared by the pressureless sintering. The relative density (ρr) was measured by the Archimedes method, the resistivity (R) was measured by the van...
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Tin dioxide based ceramics doped with ZnO, Sb2O3 and ZnO-Sb2O3 were prepared by the pressureless sintering. The relative density (ρr) was measured by the Archimedes method, the resistivity (R) was measured by the van der Pauw method, and the mi-crostructure and crystal structure were measured by scanning electron microscope. Then the internal relationship between the material and structure were analyzed. The results indicate that ZnO can improve the sintering characteristics of the material;the ρr increases and then decreases with the increase of ZnO, and the optimal content of ZnO is 1.0% (mole fraction, the same below). However, the ρr decreases with the increase of Sb2O3;the R decreases at first, and then increases and decreases at last. The ρr and R of the material are good when Sb2O3 content is 0.5%. The SnO2 based ceramic doped with 1.0% ZnO-0.5% Sb2O3 and sintered at 1400°C has high performance;the ρr is 97% and the R is 0.1099 Ω·cm.
Ga dopping GaxPb1-xTe(x=0.01-0.05) compounds were prepared by melting reaction method, and the in-c fluence of Ga content on the thermoelectric properties were investigated. The results showed that temperature dopende...
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Ga dopping GaxPb1-xTe(x=0.01-0.05) compounds were prepared by melting reaction method, and the in-c fluence of Ga content on the thermoelectric properties were investigated. The results showed that temperature dopendent carrier concentration increased and the hall mobility decreased with increasing Ga content, which indicated that the carrier scattering mechanism gradually changed from an acoustical scattering to the interaction between an acoustical phone and an ionized impurity scattering as x increased. All samples show n-type conduct and the absolute Seebeck coefficient values and the electric conductivity increase significantly with increasing Ga content.
The layered perovskite-type organic-inorganic hybrids (CnH2n+1NH3)2 MnCl4 (n=2, 4, 6, 8, 10, 12) were synthesized in solution and their structures were characterized. The results showed that the structures of the prod...
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The layered perovskite-type organic-inorganic hybrids (CnH2n+1NH3)2 MnCl4 (n=2, 4, 6, 8, 10, 12) were synthesized in solution and their structures were characterized. The results showed that the structures of the products were independent on the reaction initial temperature. The X-ray diffraction (XRD) patterns and the scanning electron microscopy (SEM) images of the products demonstrated that the hybrids crystallize very well and had typical layered structures. The interlayer distance of each hybrid was obtained from the XRD patterns. It was linear dependent on the carbon atom number in the organic chain and the organic chains interdigitated between the two adjacent inorganic sheets.
The solubility of layered perovskite-type organic-inorganic hybrids (CnH2n+1 NH3)2MCl4 (where M = Mn, Co, Cu, Zn;n = 2, 4, 6, 8, 10, 12) in seven kinds of solvent are obtained by atomic absorption spectrometry and tit...
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The solubility of layered perovskite-type organic-inorganic hybrids (CnH2n+1 NH3)2MCl4 (where M = Mn, Co, Cu, Zn;n = 2, 4, 6, 8, 10, 12) in seven kinds of solvent are obtained by atomic absorption spectrometry and titration method. The solvents are sherwood oil, cyclohexane, acetone, trichloromethane, DMF, methanol and water. The results show that the hybrids are prone to dissolve in polar solvent. This is attributed to the polarity of the hybrids. The hybrids disassembly dissolve when the interaction between the ammonium and the electron-donating group of the solvent is stronger than that between the organic and the inorganic parts in the hybrids. The series of M = Zn and Co have better solubility in the polar solvent than that of M = Mn and Cu and this is presumably because there are weaker interactions between the organic and inorganic parts in hybrids of M = Zn and Co.
Sodium potassium bismuth titanate (KNBT) slurry with high plasticity was prepared by the viscous polymer processing. The effects of milling time, bonding agent content, dispersant content, and pH value on the rheologi...
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Sodium potassium bismuth titanate (KNBT) slurry with high plasticity was prepared by the viscous polymer processing. The effects of milling time, bonding agent content, dispersant content, and pH value on the rheological properties were investigated by rheograms, and the optimal technological parameters were investigated. The KNBT fibers with improved properties were fabricated via an extruding machine. The results show that the slurry has optimal rheological behavior when the milling time is 16 h, the pH value is 7, the bonding agent content is 1.22% (in mass, the same below), and the dispersant content is 0.4%.
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.
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