Home About us Contact
|
Home About us Contact | ||
|
|
||
High Volume Fraction (high + volume_fraction)
Selected AbstractsEvaluation of double-crystal SANS data influenced by multiple scatteringJOURNAL OF APPLIED CRYSTALLOGRAPHY, Issue 3-1 2000aroun Evaluation of small-angle neutron scattering (SANS) data is often complicated by multiple scattering effects if large particles of relatively high volume fraction have to be studied and dilution or contrast reduction is impossible. The use of pin-hole SANS instruments is often limited due to the contradictory requirements of high resolution and short wavelength needed to keep scattering contrast as low as possible. Double crystal (DC) SANS diffractometers of Bonse-Hart and bent-crystal type are useful alternatives in such cases, as they permit reaching very high resolution with thermal neutrons. A method for SANS data evaluation suited to DC instruments is presented. It includes the common scheme of the indirect Fourier transformation method, but takes multiple scattering into account. The scattering medium is described by the frequency function g(x) defined as the cosine Fourier transform of slit-smeared data. Although a simplistic model of polydisperse spheres is used to represent g(x), resulting g(x) function and some integral parameters are independent of this model. Tests on simulated data show, that the method reproduce well true values of microstructural parameters, though systematic errors are observed in the cases when the unscattered part of incident beam completely disappears. If the scattering power Effects of microstructure on the compressive yield stressAICHE JOURNAL, Issue 1 2000Glenn M. Channell The effects of microstructure on the compressive properties of aggregated alumina suspensions are determined by intentionally introducing heterogeneities into the suspension. Suspensions are prepared at a high volume fraction and diluted with low shear hand mixing to a series of initial concentrations. As the initial concentration is increased, larger heterogeneities are introduced, and the suspension becomes more compressible relative to the compressive yield stress of the uniform suspension. A simple model is proposed in which the heterogeneous suspensions compress by rearrangement of the dense aggregates until a critical concentration (,c, which coincides with the volume fraction prior to dilution) is reached. Above ,c, the suspensions consolidate identically to the uniform suspension. With a single fitting parameter (the size of the heterogeneities), the model shows semiquantitative agreement with the experimental data. [source] Effect of Volume Fraction of Material on Separation by Density Difference in a Liquid-Fluidized Bed of Inert ParticlesCHEMICAL ENGINEERING & TECHNOLOGY (CET), Issue 7 2010Y. Tatemoto Abstract A liquid-fluidized bed was used to separate a pure material from a mixture. A quantity of relatively large sized material was immersed in an inert-particle fluidized bed and the behavior of materials was examined for different liquid velocities. In particular, the volume fraction of the material was varied and its effect on the separation characteristics was examined. The material floats on the inert-particle fluidized bed when the density of the material is lower than the apparent density of the bed, regardless of the volume fraction of the material. The apparent density of the bed can be adjusted by changing the liquid velocity. The materials in the upper portion of the bed affect the properties of the bed below them, i.e., the void fraction decreases and the apparent density increases in the inert-particle suspension when materials are present in the upper portion of the bed. Therefore, the materials float on the bed although the apparent density of the inert-particle suspension obtained from the case without material is less than the density of the material at a relatively high volume fraction of material. This phenomenon occurs more easily for lighter and smaller materials. This means that small inert particles and low liquid velocities are the optimum operating conditions for the separation. [source] Effect of carbide volume fraction on the oxidation of austenitic Fe-Cr-C alloysMATERIALS AND CORROSION/WERKSTOFFE UND KORROSION, Issue 6 2006L. B. Susanto Abstract A series of Fe-15Cr-(2-3)Mo alloys (compositions in weight percent) was produced with different carbon concentrations, to control the distribution of chromium between matrix metal and M23C6 precipitates. The alloys were oxidized in the austenitic state at 850°C in pure oxygen, with and without a pre-oxidation treatment at low oxygen potential, where no iron oxide could form. Protective, chromia-rich scaling took place if the chromium concentration at the metal-scale interface was high enough. This concentration was controlled by the original alloy matrix chromium concentration, and whether or not a high diffusivity ferrite zone developed at the surface by decarburization. Ferrite zone formation was assisted by pre-oxidation at low oxygen potentials. The value of the carbides as suppliers of additional chromium was demonstrated by comparison with the oxidation performance of carbide-free alloys of corresponding matrix chromium levels. However, because dissolution of the coarse carbides could be slow, alloys with high volume fractions of large carbides were unsuccessful. [source]
| | |||||||||