Volume fraction

About: Volume fraction is a research topic. Over the lifetime, 16312 publications have been published within this topic receiving 374181 citations.

Development of an additive equation for predicting the electrical conductivity of carbon‐filled composites

Abstract: The electrical conductivity of polymeric materials can be increased by the addition of carbon fillers. The resulting composites can be used in applications such as electrostatic dissipation and interference shielding. Electrical conductivity models are often proposed to predict the conductivity behavior of these materials. The electrical conductivity of carbon-filled polymers was studied here by the addition of three single fillers to nylon 6,6 and polycarbonate in increasing concentrations. The fillers used in this project were carbon black, synthetic-graphite particles, and milled pitch-based carbon fibers. Materials were extruded and injection-molded into test specimens, and then the electrical conductivity was measured. Additional material characterization tests included optical microscopy for determining the filler aspect ratio and orientation. The filler and matrix surface energies were also determined. An updated model developed by Mamunya and others and a new additive model (including the constituent conductivities, filler volume fraction, percolation threshold, constituent surface energies, filler aspect ratio, and filler orientation) fit the electrical conductivity results well. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 2280–2299, 2003

A systematic investigation of elastic moduli of Wc-Co alloys

Abstract: Measurements of Young’s modulus, shear modulus, compression modulus, and Poisson’s ratio on WC-(1 ~ 30) wt pct Co alloys were carried out by dynamic resonance method. The effects of volume fraction of the WC phase, the carbon content, and the WC particle-size on the elastic moduli were investigated in some detail. The result shows that the various elastic moduli of the alloys depend solely on volume fractions of the constituent phases and they invariably fall within Hashin and Shtrikman’s bounds. Moreover, the moduli are found to be approximated by Paul’s “strength of materials” type formulas. It is concluded that elastic behavior of the alloys can be essentially predicted on the basis of a simplified geometrical model of WC particles embedded in continuous cobalt matrix.

Sintering of TiO2–Al2O3 Composites: A Model Experimental Investigation

Abstract: In recent theoretical work we have shown that the sintering of a composite is strongly affected by the shear deformation of the continuous phase. This phenomenon was studied experimentally in a model system consisting of a TiO2 matrix dispersed with nondensifying agglomerates of Al2O3. The results of this study are reported here. Several interesting results were obtained: (a) The experimentally obtained sintering rate of the composite could be successfully predicted by measuring the concomitant shear and densification rate of the matrix phase in a sinter-forging experiment and using the developed analysis; (b) the densification rate of the composite changed with the volume fraction of the dispersed phase, but was unaffected by the size of the dispersed phase; and (c) processing flaws appeared to form only when the size of the dispersed phase was greater than about 10 μm. A technique for measuring the parameter β, which was used to correlate theory and experiments, is described. The procedures used for preparation of powders (from alkoxides) and the green compacts are also described in detail.

Investigation into the effects of slip boundary condition on nanofluid flow in a double-layer microchannel

Abstract: In this research, the laminar flow and heat transfer of kerosene/MWCNT nanofluid in a novel design of a double-layer microchannel under the influence of oscillating heat flux and slip boundary condition have been studied. This research has been investigated in the dimensionless lengths of (λ 1) 1/3, 2/3 and 3/3 and dimensionless slip velocity coefficients ranging from 0.001 to 0.1. The suspension of nanoparticles in kerosene as the base fluid has been studied in Reynolds numbers of 1–100 and volume fractions of 0–8%. The results indicate that, by using novel design of double-layer microchannel in λ 1 = 1/3, the maximum rate of performance evaluation criterion is obtained and by increasing the slip velocity coefficient, the amount of PEC becomes significant. Among the studied cases, in all Reynolds numbers and volume fractions, the dimensionless length of 1/3 has the maximum amount of friction coefficient. Also, by enhancing the volume fraction of nanoparticles, slip velocity coefficient, Reynolds number and significant reduction in thermal resistance of solid wall, Nusselt number enhances.