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Volume fraction
About: Volume fraction is a research topic. Over the lifetime, 16312 publications have been published within this topic receiving 374181 citations.
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TL;DR: In this paper, particle velocity distributions were measured for a flow of 75-microm FCC (fluidized catalytic cracking) particles in a CFB (circulating fluidized bed) using a new video-digital camera technique.
Abstract: Particle velocity distributions were measured for a flow of 75-{micro}m FCC (fluidized catalytic cracking) particles in a CFB (circulating fluidized bed) using a new video-digital camera technique. From the spread of particle histograms, a random oscillating particle velocity was determined. This random velocity was used to compute the powder viscosity with the help of dense-phase kinetic theory of granular flow. There was excellent agreement between this kinetic-theory measurement and previous macroscopic viscosity measurements. The dimensionless group kinematic viscosity divided by the oscillating velocity and particle diameter correlated all available data as a function of particle volume fraction.
103 citations
TL;DR: In this article, composites based on the Zr55Al10Cu30Ni5 bulk metallic glass forming alloy, containing up to 17.5 vol % W particles were synthesized by mechanical alloying, and it is suggested that both the matrix and the nanocrystalline particles contribute to the overall hardness of the composites.
Abstract: Composites based on the Zr55Al10Cu30Ni5 bulk metallic glass forming alloy, containing up to 17.5 vol % W particles were synthesized by mechanical alloying. Milling produces a metallic glass matrix with a homogeneous dispersion of nanoscale W particles. The composites exhibit almost the same thermal stability and no reduction of the supercooled liquid region compared to the particle-free metallic glass despite some small amount of dissolution of W into the glassy matrix. The viscosity in the supercooled liquid increases with increasing volume fraction of particles. This will be discussed with respect to the contribution of the particles as well as to changes in matrix composition and in the free volume of the material in the framework of the free volume model for viscous flow. Independent of the W content, the samples behave as moderately strong glasses. The viscous flow of the supercooled liquid is used to consolidate dense bulk samples. The Vickers hardness, HV, of the composites increases with increasing volume fraction of particles. It is suggested that both the matrix and the nanocrystalline particles contribute to the overall hardness of the composites.
103 citations
TL;DR: In this article, a model for particle behavior at the liquid/solid interface in aluminum metal matrix composites is proposed. But the model is not suitable for the case of large numbers of particles.
Abstract: Directional solidification experiments in a Bridgman-type furnace were used to study particle behavior at the liquid/solid interface in aluminum metal matrix composites. Graphite or siliconcarbide particles were first dispersed in aluminum-base alloysvia a mechanically stirred vortex. Then, 100-mm-diameter and 120-mm-long samples were cast in steel dies and used for directional solidification. The processing variables controlled were the direction and velocity of solidification and the temperature gradient at the interface. The material variables monitored were the interface energy, the liquid/particle density difference, the particle/liquid thermal conductivity ratio, and the volume fraction of particles. These properties were changed by selecting combinations of particles (graphite or silicon carbide) and alloys (Al-Cu, Al-Mg, Al-Ni). A model which considers process thermodynamics, process kinetics (including the role of buoyant forces), and thermophysical properties was developed. Based on solidification direction and velocity, and on materials properties, four types of behavior were predicted. Sessile drop experiments were also used to determine some of the interface energies required in calculation with the proposed model. Experimental results compared favorably with model predictions.
103 citations
TL;DR: In this paper, the variation of electrical resistivity of an insulator-conductor composite, namely, waxgraphite composite, with parameters such as volume fraction, grain size, and temperature has been studied.
Abstract: The variation of electrical resistivity of an insulator‐conductor composite, namely, wax‐graphite composite, with parameters such as volume fraction, grain size, and temperature has been studied. A model is proposed to explain the observed variations, which assumes that the texture of the composite consists of insulator granules coated with conducting particles. The resistivity of these materials is controlled mainly by the contact resistance between the conducting particles and the number of contacts each particle has with its neighbors. The variation of resistivity with temperature has also been explained with the help of this model and it is attributed to the change in contact area.
103 citations
TL;DR: In this paper, the effect of particle shape on the low-shear yield strength of sub-liquidus basalts is examined, and the authors conclude that shape is important in determining the volume fraction range over which suspensions exhibit a finite yield strength.
103 citations