The influences of sintering temperature, soaking time and annealing time on the quality factor of Ba(Mg/13Nb2/3)O3 microwave dielectric ceramic were investigated. The result showed that Qf value increased as the sinte...
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The influences of sintering temperature, soaking time and annealing time on the quality factor of Ba(Mg/13Nb2/3)O3 microwave dielectric ceramic were investigated. The result showed that Qf value increased as the sintering temperature increasing. It was ascribed to the increasing of the relative density and ordering parameter S. The maximum value of Qf, 49500 GHz, was gained at 1550°C. With soaking time increasing, Qf value increased. The increasing of B-site 1:2 ordering degree and grain size should be responsible for the improvement of Qf value. When soaking time was 16 h, Qf value reached 58000 GHz. Annealing time had great effect on Qf value. With annealing time increasing, Qf value increased quickly. This was because of the improvement of B-site 1:2 ordering caused by annealing. A high Qf value, 71500 GHz, was acquired when annealing time was 48 h.
The transient temperature field analysis aims at the thermal response of LPG vessel under pool fire surrounding environment. The finite element analysis method is used to calculate the temperature field. The thermal b...
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The transient temperature field analysis aims at the thermal response of LPG vessel under pool fire surrounding environment. The finite element analysis method is used to calculate the temperature field. The thermal boundary conditions of LPG vessel are determined according to heat transfer theory and calculated by the software PLGS99. The results show that the maximum temperature gradient of vessel appears near the highest surface where the liquid can reach, and fluctuation of liquid surface is the main reason of high temperature gradient.
Space symmetry of prehnite, which occurs in cavities and veins within Skarn from the Tieshan iron mineral deposit,Daye,Hubei province,Central China,has been determined using selected area electron diffraction (SAED) a...
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Space symmetry of prehnite, which occurs in cavities and veins within Skarn from the Tieshan iron mineral deposit,Daye,Hubei province,Central China,has been determined using selected area electron diffraction (SAED) and convergent-beam electron diffraction (CBED) on the submicrometer *** results confirm that the natural prehnite may have the structure with symmetry *** unit-cell parameters of investigated prehnite (a=0.458nm,b=0.555nm,and c=1.853nm) have been calculated by using the multicrystal diffraction rings of gold,the internal standard.
This paper studies the temperature distribution of BN, an insulating material, sintered in the Spark Plasma Sintering ( SPS) system. The temperature distributions of BN at different heating rates were measured , which...
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This paper studies the temperature distribution of BN, an insulating material, sintered in the Spark Plasma Sintering ( SPS) system. The temperature distributions of BN at different heating rates were measured , which showed that seeking for an over high heating rate in SPS is not as desirable as controlling of a suitable heating rate in order to have a fast sintering with a uniform temperature distribution.
The texture of interfacial zone between cement paste and quartz in the cement-based composites containing polyvinyl alcohol (PVA), methylcellulose (MC) and their potyblend in an amount of 10 wt % with respect to cemen...
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The texture of interfacial zone between cement paste and quartz in the cement-based composites containing polyvinyl alcohol (PVA), methylcellulose (MC) and their potyblend in an amount of 10 wt % with respect to cement, as well as the texture of dehydrated bodies of PVA, MC, and the potyblend solutions, were investigated with SEM. The network texture of the dehydrated polyblend is confirmed by comparing the texture of dehydrated bodies of PVA and MC. The network texture has restrained the movement of polyblend molecules in the cement mortar but is helpful to forming a coherent interface between cement paste and quartz. The key factor of forming the coherent interface is not the neutralization reaction between H + from hydrolysis of quarts: and OH- from hydration of cement, but the electrostatic attraction and the chemical reaction between polar groups on the polyblend molecule and cations and onions from hydrolysis of quartz and hydration of cement, respectively. The model of the coherent interface formation is that excessive [HSiO3]- and [SiO3]2- onions are bonded with the hydrated cations such as Ca2+ and Al3+ , which is confirmed by the gel containing Ca and Si on the quartz surface.
By using such flier-plate material,quasi-isentropic compression can be *** on it,hypervelocity launching is further *** a result,an extremely high dynamic pressure can be obtained in lab.ratory,offering a practical me...
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By using such flier-plate material,quasi-isentropic compression can be *** on it,hypervelocity launching is further *** a result,an extremely high dynamic pressure can be obtained in lab.ratory,offering a practical method for the comprehensive determination of materials behavior,response,equation-of-state and properties in dynamic loading process.
New layered perovskites, KSr2Nb3O10 and two new protonated niobates HSr2 Nb3O10·1.2H2O and HSr2Nb3O10,were synthesized by solid state reaction and ion-exchange reaction. These new compounds -were characterized by...
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New layered perovskites, KSr2Nb3O10 and two new protonated niobates HSr2 Nb3O10·1.2H2O and HSr2Nb3O10,were synthesized by solid state reaction and ion-exchange reaction. These new compounds -were characterized by EPMA, AAS, XRD, IR, DTA and so on. The structure may be described as treble perovskite sheets [Sr2Nb3O10]- interleaved with K+ ,H3O + or H+. These new compounds are new members of the Dion-Jacob-sonseries with n=3 for the general formula M[An-1 NbnO3n+1], and their indexed X-ray powder diffraction data were first reported in the paper.
The solid solutions of Al2(1.x)MgxTi 1+xO5 (x=0,0.01,0.05,0.1) were fabricated by the solid phase reaction method, and they were sintered under normal pressure. The thermal performance of Al2(1-x)MgxTi1+xO 5 was mainl...
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The solid solutions of Al2(1.x)MgxTi 1+xO5 (x=0,0.01,0.05,0.1) were fabricated by the solid phase reaction method, and they were sintered under normal pressure. The thermal performance of Al2(1-x)MgxTi1+xO 5 was mainly investigated. The results show that, the additive MgTi2O5 can not only restrain the decomposition of Al 2TiO5, but also greatly improve the densification of the solid solutions. With increasing mole percent of x, the thermal stability of Al2(1-x)MgxTi1+xO5 increases and the expansion coefficient decreases.
W-Mo system functionally graded material with density gradient, which can be applied to dynamic high-pressure technology, was prepared by hot-pressing at 1573K. In order to obtain fully dense body, suitable amount of ...
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W-Mo system functionally graded material with density gradient, which can be applied to dynamic high-pressure technology, was prepared by hot-pressing at 1573K. In order to obtain fully dense body, suitable amount of Ni and Cu was added. The FGM has quasi-continuous density variation in the thickness direction.
Polycrystalline PbTe samples have been implanted by Sn+ ion at 200KeV with doses of 6×1016 and 1×1017 ions/cm2 in order to create a modified Pb1-xSnxTe layers with gradation of carrier concentration. The ele...
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Polycrystalline PbTe samples have been implanted by Sn+ ion at 200KeV with doses of 6×1016 and 1×1017 ions/cm2 in order to create a modified Pb1-xSnxTe layers with gradation of carrier concentration. The electrical conductivity, Hall coefficient and thermoelectric power measurements have been carried out at 300K on the implanted samples. The effect of Sn+ ion implantation on structure of PbTe has been investigated using X-ray Diffraction (XRD), Scanning Electron Microscope (SEM) and X-ray Photoelectron Spectroscopy (XPS). The results indicate the possible presence of Pb1-xSnxTe(x=0.2 approx. 0.25) phase during the ion-implantation processes.
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