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排序方式: 共有430条查询结果,搜索用时 140 毫秒
111.
Ramesh Chandra Mallik Christian Stiewe Gabriele Karpinski Ralf Hassdorf Eckhard Müller 《Journal of Electronic Materials》2009,38(7):1337-1343
The properties of Co4Sb12 with various In additions were studied. X-ray diffraction revealed the presence of the pure δ-phase of In0.16Co4Sb12, whereas impurity phases (γ-CoSb2 and InSb) appeared for x = 0.25, 0.40, 0.80, and 1.20. The homogeneity and morphology of the samples were observed by Seebeck microprobe and scanning
electron microscopy, respectively. All the quenched ingots from which the studied samples were cut were inhomogeneous in the
axial direction. The temperature dependence of the Seebeck coefficient (S), electrical conductivity (σ), and thermal conductivity (κ) was measured from room temperature up to 673 K. The Seebeck coefficient of all In-added Co4Sb12 materials was negative. When the filler concentration increases, the Seebeck coefficient decreases. The samples with In additions
above the filling limit (x = 0.22) show an even lower Seebeck coefficient due to the formation of secondary phases: InSb and CoSb2. The temperature variation of the electrical conductivity is semiconductor-like. The thermal conductivity of all the samples
decreases with temperature. The central region of the In0.4Co4Sb12 ingot shows the lowest thermal conductivity, probably due to the combined effect of (a) rattling due to maximum filling and
(b) the presence of a small amount of fine-dispersed secondary phases at the grain boundaries. Thus, regardless of the non-single-phase
morphology, a promising ZT (S
2
σT/κ) value of 0.96 at 673 K has been obtained with an In addition above the filling limit. 相似文献
112.
Lage E Kirchhof C Hrkac V Kienle L Jahns R Knöchel R Quandt E Meyners D 《Nature materials》2012,11(6):523-529
Magnetoelectric composite materials are promising candidates for highly sensitive magnetic-field sensors. However, the composites showing the highest reported magnetoelectric coefficients require the presence of external d.c. magnetic bias fields, which is detrimental to their use as sensitive high-resolution magnetic-field sensors. Here, we report magnetoelectric composite materials that instead rely on intrinsic magnetic fields arising from exchange bias in the device. Thin-film magnetoelectric two-two composites were fabricated by magnetron sputtering on silicon-cantilever substrates. The composites consist of piezoelectric AlN and multilayers with the sequence Ta/Cu/Mn(70)Ir(30)/Fe(50)Co(50) or Ta/Cu/Mn(70)Ir(30)/Fe(70.2)Co(7.8)Si(12)B(10) serving as the magnetostrictive component. The thickness of the ferromagnetic layers and angle dependency of the exchange bias field are used to adjust the shift of the magnetostriction curve in such a way that the maximum piezomagnetic coefficient occurs at zero magnetic bias field. These self-biased composites show high sensitivity to a.c. magnetic fields with a maximum magnetoelectric coefficient of 96 V cm(-1) Oe(-1) at mechanical resonance. 相似文献
113.
Eduardo Navarro de Andrade Eric Skowron Victor W. Goldschmidt Eckhard A. Groll 《International Journal of Refrigeration》1999,22(6):499
The concentration of oil in refrigerants (while in liquid state) can be measured with an acoustic velocity sensor. The transit time for an acoustic signal can be related to the oil concentration and temperature of the liquid mixture. The performance of the sensor is dependent on the properties of the oil and refrigerant, and their miscibility. In general, a thorough calibration becomes necessary. It is shown in this paper that for concentrations less than 10%, an approximation can be made for the estimate of concentration hence eliminating the need for an elaborate calibration procedure. 相似文献
114.
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116.
Mark Bertram Corrine Manschot‐Lawrence Eckhard Flöter Uwe T. Bornscheuer 《European Journal of Lipid Science and Technology》2007,109(2):180-185
A microtiter plate (MTP) method was developed to determine the quality of fats that are used in large‐scale processing using lipase catalysis. Two assay formats were followed: In the first approach, the fats were interesterified with p‐nitrophenol laurate using a lipase from Thermomyces lanuginosa; in the second approach, pH indicators were added to the fat samples containing lipase. A blind study using 29 fats showed that the MTP method using p‐nitrophenol as pH indicator allowed a rapid and reliable assignment of bad fats and an acceptable differentiation between fats of moderate and good quality. 相似文献
117.
This article introduces a new high-pressure process for the gentle drying, micronisation and formulation of high molecular mass gelatine. Spray drying of gelatine solutions is a well-established process for very low molecular weight gelatine, aqueous solutions containing low gelatine concentrations or gelatine solutions containing viscosity reducing additives. In the introduced process, supercritical CO2 was applied to micronised aqueous gelatine solutions and was then expanded from high pressure into a spraying chamber to remove the water content by extraction and evaporation under moderate conditions. The resulting product was analysed using common powder analysis methods. Aqueous gelatine solutions with a dry mass content of up to 50 wt.% with a molecular mass of 156,000 g mol?1 were pulverised and dried with this process, with only limited degradation by hydrolysis during processing. 相似文献
118.
The mechanical properties of spray dried granules are decisive with regard to further applications and can be modified via internal granule structure. To obtain the correlations between structural and mechanical properties, necessary experiments are often time and resource consuming. The simulation of varied granule structures and their effect on resulting mechanical properties seems to be a promising approach.In this paper, a model of the particulate internal structure of a spray dried granule was generated with the Discrete Element Method (DEM) based on real structure parameters. The model considers real primary particle number, particle size distribution and radial granule inhomogeneity, what results in the implementation of granule shell thickness and macro void. The internal structure of simulated granules showed significant influence on their mechanical properties. An increase of granule shell thickness and packing density of the primary particles within the shell results in fracture strength increase accompanied by decreasing fracture strain. The simulated reduction of the solid bridge bond size between the primary particles representing the decreasing binder amount leads to decreasing fracture strength and strain as previously determined experimentally (Eckhard et al., 2014). Consequently, the DEM is appropriate for evaluating the effect of changed real internal structure parameters on resulting mechanical granule properties. 相似文献
119.
Hanlin Gu Lars Bumke Christoph Chluba Eckhard Quandt Richard D. James 《Materials Today》2018,21(3):265-277
In recent years examples of unprecedented functional and structural fatigue resistance and lowered hysteresis in shape memory alloys have been achieved by combining conditions of supercompatibility between phases with suitable grain size and a favorable array of fine precipitates. We collect, review and compare these examples to elucidate the relative roles of these factors, especially in the case of the more demanding stress-induced phase transformations, and we pose key open questions. The control of these factors lends itself to systematic alloy development. Taken together, these results point to significant opportunities to discover improved shape memory alloys as well has new reversible transforming multiferroics. 相似文献
120.
The critical resolved shear stress (CRSS), τ
0, of peak-aged single crystals of the γ′-hardened commercial nickel-base superalloy NIMONIC 105 has been measured as a function of temperature T and orientation [hkl] of the compression axis. The same measurements have been carried out for the two constituent phases of NIMONIC 105: for
the single-phase γ matrix and for the single-phase L12-long-range ordered γ′ phase. The value of T ranged from 283 to 1150 K, and the following orientations were studied: [001], [011],
, and
. The specimens were compression tested. The τ
0 values of NIMONIC 105 and of the γ′ phase are anisotropic; the anisotropy of NIMONIC 105 is similar to that of the γ′ phase, but less pronounced. The τ
0 of the γ phase is isotropic. The τ
0 values of the γ and of the γ′ phase vary with T, whereas the τ
0 of NIMONIC 105 is nearly independent of T for 400 K≤T≤1000 K. A model is presented that relates the function τ
0 ([h, k, l], T) of NIMONIC 105 to the analogous functions of its constituent γ and γ′ phase. 相似文献