Showing papers on "Volume fraction published in 1979"
TL;DR: In this paper, a spatially homogeneous rate theory was developed to describe the time rate of change of the radius of a spherical particle embedded in a configurationally random array of particles of like nature but differing sizes.
478 citations
TL;DR: In this article, the electrical conductivity of cuprous chloride containing a dispersion of fine alumina particles was studied as a function of volume fraction (0.212) and particle size ( 0.3 and 0.06 μm initial particle size).
Abstract: The electrical conductivity of cuprous chloride containing a dispersion of fine alumina particles was studied as a function of volume fraction (0–0.212) and particle size (0.3 and 0.06 μm initial particle size). At low temperatures the ionic conductivity may be increased by as much as two orders of magnitude. The enhanced conductivity, Δσ, was proportional to the surface area of the added alumina. Both these data and the earlier data of Liang (1) were fitted to a relation, where is the radius of the alumina dispersoids and the volume fraction.
247 citations
TL;DR: In this paper, the authors derived expressions relating the geometric and thermodynamic properties of highly concentrated, monodisperse emulsions to the volume fraction of the dispersed phase for the model of infinitely long cylindrical drops.
178 citations
TL;DR: It is shown both theoretically and experimentally that the above solution must be generalized for iontophoresis of ions which are confined to the extracellular space of the brain and that K ÷ behaves anomalously and therefore probably migrates by transcellular routes.
156 citations
TL;DR: In this article, a n application of the self-consistent method (s.c.m.) is given to the problem of determining overall moduli for short fiber reinforced composites.
Abstract: A n application of the self-consistent method (s.c.m.) is given to the problem of determining overall moduli for short fibre reinforced composites. It is assumed that the fibres can be considered to be spheroids. For fully-aligned fibres, the numerical results are presented in graphical form and show the dependence of the compliances on aspect ratio and volume fraction. It is shown that an aspect ratio of 100 is essentially infinite. By making use of some (albeit tentative) ideas on how to handle the misalignment of fibres the s.c.m. results are shown to compare favourably with experiment.
92 citations
TL;DR: In this article, the separation between the isotropic and anisotropic component of some Raman bands of polar molecules is studied as a function of concentration in different solvents.
Abstract: The separation between the isotropic and the anisotropic component of some Raman bands of polar molecules is studied as a function of concentration in different solvents. It is found that it depends linearly on the ratio between the volume fraction and the static dielectric constant of the solution, and becomes zero at a finite concentration. It is suggested that this concentration threshold is related to the relaxation time of the vibrational energy. An explanation is proposed for the observed dependence on the dielectric constant.
87 citations
TL;DR: In this article, the results of spin coating studies of an electron resist using several different solvents were reported, and two problems which were frequently observed during the spin-coating studies were the appearance of orange peel coatings and the formation of cloudy films.
Abstract: This paper reports the results of spin coating studies of an electron resist using several different solvents. Two problems which were frequently observed during the spin coating studies were the appearance of orange peel coatings and the formation of cloudy films. The appearance of orange peel is attributed to the rapid drying of low-boiling solvents. The formation of a cloudy film is believed to be caused by the hygroscopic nature of the solvents used. The resist film thickness can be approximated by the relationship l = KC2.1/ω0.5, where l is film thickness, C is volume fraction of polymer resist, K is a constant and ω is the rotation speed. The results are compared with the theoretical modelings of Washo (1) and Meyerhofer (2).
80 citations
TL;DR: In this article, the viscoelastic properties of a flocculated dispersion are explained in terms of a network model and the modulus and strength are proportional to the first power of the volume fraction and weakly dependent on the particle size.
75 citations
TL;DR: In this article, a theory was developed to describe the thermomechanical behavior of the boundary interphase, which is an area between filler and matrix, which contains both areas of adsorption interaction in polymer surface layers into filler particles, as well as an area of mechanical imperfections.
Abstract: A previous study (1) on the thermomechanical behaviour of metal-filled Epoxies led us to conclude that the concept of the boundary interphase is a very useful tool for describing quantitatively the quality of adhesion between the matrix and the filler particles. It was shown that this interphase exists in reality and is an area between filler and matrix, which contains both areas of adsorption interaction in polymer surface layers into filler particles, as well as an area of mechanical imperfections. In the present paper, under the assumption that the interphase is homogeneous and isotropic, exhibiting perfect adhesion with both main phases, a theory was developed to describe the thermomechanical behaviour of this interphase. Thermal expansion coefficients and volume fraction of the interphase of a large number of composites were determined and the effect of various parameters, such as temperature, volume fraction of filler and particle size, were examined for specimens exhibiting imperfect as well as perfect adhesion between matrix and filler.
55 citations
TL;DR: A large number of ferrite-pearlite steels have been examined and measurements made of grain size, pearlite volume fraction, degree of precipitation hardening, and thickness of grain-boundary carbid as discussed by the authors.
Abstract: A large number of ferrite–pearlite steels have been examined and measurements made of grain size, pearlite volume fraction, degree of precipitation hardening, and thickness of grain-boundary carbid...
53 citations
TL;DR: Steady-state creep-rates of polycrystalline ice were investigated as a function of temperature, grain-size, and inclusion concentration through uniaxial compression in the laboratory as discussed by the authors.
Abstract: Steady-state creep-rates of polycrystalline ice were investigated as a function of temperature, grain-size, and inclusion concentration through uniaxial compression in the laboratory. Samples were run at a constant load with the temperature systematically varied between about —5°C and —40°C. The presence of inclusions inhibits dynamic recrystallization and grain growth; the average crystal size produced by recrystallization is inversely proportional to the inclusion concentration. At temperatures above —8°C, creep-rate is enhanced by about a factor of two. This appears to be the result of the combined effects of recrystallization with accompanying grain growth and grain-boundary sliding. Over the temperature range —10°C to —40°C, the apparent activation energy for creep increases with increasing volume fraction of inclusions. This is apparently due to a thermally activated process which is modified by internal stresses created by the inclusions.
TL;DR: In this paper, the decomposition of the supersaturated solid solution of an Al-3.2wt% Zn-2.2 wt% Mg alloy has been investigated in the temperature of 20 to 200° C, by small-angle X-ray scattering, electrical resistivity and mechanical measurements.
Abstract: The decomposition of the supersaturated solid solution of an Al-3.2wt% Zn-2.2 wt% Mg alloy has been investigated in the temperature of 20 to 200° C, by small-angle X-ray scattering, electrical resistivity and mechanical measurements. On the basis of the results obtained, three subsequent stages of the decomposition process can be distinguished. Between 20 and 70° the basic process is the nucleation and growth of G.P. zones, the volume fraction of which increases logarithmically with time. A transition stage is observed between 80 and 100° in which the volume fraction increases linearly with time. Above 90° C, the growth kinetics of the volume fraction shows a definite incubation period at the beginning of ageing, while the yield stress increases monotonically. In the temperature range 100 to 160° C, the formation of theη′ phase takes place. Below 100° a linear connection between the yield stress and (fR)1/2 is found from which the specific surface energy to cut a G.P. zone is calculated to be Γ0= 0.21 Nm m−2.
TL;DR: In this article, the critical resolved shear stress (CRSS) was measured in compression between room temperature and 1900 K. The significant effect of various particle shapes on the CRSS can be explained quantitatively by the transition from cutting by strongly coupled dislocation pairs to Orowan looping of single dislocations.
TL;DR: An alkali resistant Metglas fiber of composition Fe29Ni49P14B6Si2 was used in 2.5cm lengths as discontinuous reinforcement for mortar and the force-displacement curves for pull-out of roughened individual fibres embedded into mortar were measured.
Abstract: An alkali resistant Metglas fibre of composition Fe29Ni49P14B6Si2 was used in 2.5cm lengths as discontinuous reinforcement for mortar. The force-displacement curves for pull-out of roughened individual fibres embedded into mortar were measured. Composite experiments with fibres in planar random orientations have demonstrated that the first crack strength rises weakly with increasing fibre volume fraction according to the principle of non-propagating cracks. The maximum post cracking strength rises linearly with increasing volume fraction up to Vf=0.012 where it levels off due to secondary fragmentation in the matrix. The monotonic fracture behaviour of the material in nearly all respects is in accord with theoretical expectations. Under cyclic conditions, the composite undergoes progressive damage only when the maximum tensile stress per cycle penetrates beyond a critical amount into the range between the first crack strength and the maximum post-cracking strength.
TL;DR: In this paper, the dependence of anelastic strain on grain size, particle size and volume fraction at different stresses and temperatures has been studied, and a model based on different deformation mechanisms, which permits measurements of mobile dislocation fractions, has been proposed to explain the two stages.
TL;DR: In this paper, the effects of α/β interface phase on room temperature tensile properties of Ti-6Al-4V having an equiaxed primary α microstructure have been studied systematically.
Abstract: The effects of α/β interface phase on room temperature tensile properties of Ti-6Al-4V having an equiaxed primary α microstructure have been studied systematically. Due to the conditions under which it grows, manipulation of the interface phase width also results in alteration of the volume fraction of primary α in the alloy. Tensile yield strength and elongation were correlated to interface phase width and volume fraction primary α. The relative individual influence of each of these microstructural features on properties is not unambiguously clear, but evidence indicates that yield strength increases with increasing interface phase width when the interface phase exceeds about 250 nm, and elongation decreases with increasing interface phase width up to about 250 nm, and is unaffected at widths above 250 nm. It is speculated that the interface phase raises yield strength and lowers elongation by acting as a barrier to slip.
TL;DR: In this paper, the effect of total dose on the depth distribution of cavities (voids or bubbles) in nickel irradiated at 500°C with 500-keV 4He+ ions was investigated.
TL;DR: In this article, the temperature dependence of the tensile strength of polyester resins reinforced with a random-planar orientation of short glass fibers was studied and the experimental strength values at room temperature were considerably smaller than the theoretical values.
Abstract: Epoxy and unsaturated polyester resins reinforced with random-planar orientation of short glass fibers were prepared and the temperature dependence of their tensile strength was studied. The tensile strength decreases as the temperature increases, and this tendency can be expressed in terms of critical fiber length lc and apparent interfacial shear strength τ:
where σcs is the tensile strength of composite reinforced with random-planar orientation of short fibers, L is the fiber length, d is the fiber diameter, σf is the tensile strength of fiber, σm is the tensile strength of matrix, uf is the volume fraction of fiber, vm is the volume fraction of matrix, and σ′m is the stress of the matrix at fracture strain of the composite. The experimental strength values at room temperature are considerably smaller than the theoretical values, and this difference can be explained by the thermal stress produced during molding due to the large difference in the thermal expansion coefficient between glass fiber and matrix resin.
TL;DR: In this paper, the room temperature mechanical properties of the metallic glass Cu46Zr54 have been investigated as a function of aging time at 375°C (15°C belowT g).
Abstract: The room temperature mechanical properties of the metallic glass Cu46Zr54 have been investigated as a function of aging time at 375°C (15°C belowT
g). The results indicate that the tensile fracture stress and hardness of this material can be changed by such thermal processing. Fracture stress and hardness are increased with short times at temperature by structural relaxation. Also, the presence of a very small volume fraction of crystalline phase causes the shear stiffness of the material to increase markedly providing an additional increase in fracture stress and hardness. Continued devitrification causes embrittlement and the decrease of fracture stress, as predicted by the model of two-phase materials; however, hardness continues to increase, reflecting the increasing volume fraction of the harder crystalline phases. Embrittlement and decreasing fracture stress are enhanced by the stress concentration effect at the crystallites which causes void formation and growth.
TL;DR: The effects of dispersions of barium sulphate (BaSO4) particles on crack nucleation and growth in a commercially available surgical acrylic bone cement are described and a simple model is presented which is based on the nucleations and growth of voids around each BaSO4 particle.
TL;DR: There is excellent agreement between the initial experimental data, the improved design data, and the theoretical analysis of the helical capacitor sensor for determining the in situ component ratios in two-phase systems.
Abstract: A theoretical and experimental study of the helical capacitor sensor for determining the in situ component ratios in two‐phase systems is described. There is excellent agreement between the initial experimental data, the improved design data, and the theoretical analysis.
TL;DR: In this paper, critical current densities of in situ formed Cu-Nb3Sn composites with discontinuous filaments were measured as a function of superconducting volume fraction, matrix resistivity, area reduction ratio, and applied magnetic field.
Abstract: Critical current densities of in situ formed Cu-Nb3Sn composites with discontinuous filaments were measured as a function of superconducting volume fraction, matrix resistivity, area reduction ratio, and applied magnetic field. In agreement with recent modelling by Tinkham and co-workers, the effective superconducting volume fraction in a given composite was found to be field-dependent, necessitating the distinction between microstructural and electrical percolation. In composites with a low filament volume fraction, proximity effect coupling, controlled by matrix resistivity, was found to be the dominant factor determining both the composite remnant resistivity and the critical current density. For sufficiently high filament volume fractions and area reduction ratios, the remnant resistivities fall below the level of detection, as predicted by theory, and critical current densities become comparable to those of continuous filament composites. SEM, TEM, and STEM analysis reveal a dense distribution of submicron, ribbon-like Nb3Sn filaments in relatively pure Cu matrix. The microstructure of the filaments is equi-axed with an average grain size of ∼ 400A, ensuring effective flux pinning.
01 Jan 1979
TL;DR: In this article, the longitudinal Young's modulus and major Poisson's ratio of a unidirectional, short-fiber composite are found in terms of the fiber volume fraction and the tip-to-tip spacing of the fibers.
Abstract: Based on a composite-cylinder model with a short cylindrical fiber embedded in the center of a cylindrical matrix, the longitudinal Young's modulus and major Poisson's ratio of a unidirectional, short-fiber composite are found in terms of the fiber volume fraction and the tip-to-tip spacing of the fibers. The expressions obtained are then modified to account for the influence of volume fraction and aspect ratio of the fibers. These results, together with Christensen and Waals' normalized expressions, are used to calculate the Young's modulus and Poisson's ratio of a randomly-oriented chopped-fiber composite in terms of the fiber volume fraction and its aspect ratio. The theory developed is then applied to examine numerically the effects of fiber length on the Young's modulus and Poisson's ratio of short glassfiber/polyester-resin composites. The results show that the Young's modulus of both unidirectional and randomly-oriented fiber composites are strongly dependent on the fiber length; so is the Poisson's ratio, though to a lesser degree.
TL;DR: In this paper, a study of the recrystallization process in a series of samples of aluminium containing dispersions of oxide particles is made, and the effect of varying the volume fraction of oxide and the initial grain size has been investigated.
Abstract: A study has been made of the recrystallization process in a series of samples of aluminium containing dispersions of oxide particles. The effect of varying the volume fraction of oxide and the initial grain size has been investigated. Both the macroscopic and microscopic aspects of the recrystallization processes have been evaluated. The results from measurements of hardness and observation by light microscopy and by transmission electron microscopy are in accord. Nucleation events both within the grains and at intergranular sites have been found. The effect of an increasing volume fraction of oxide particles is to slow down both the formation and growth of viable nuclei.
TL;DR: In this paper, an alloy containing 0.03%C, 1.0%Mn, 0.05%Nb, and 0.006%N was solution treated at either 1300 or 1020°C prior to hot rolling.
Abstract: An alloy containing 0.03%C, 1.0%Mn, 0.05%Nb, and 0.006%N was solution treated at either 1300 or 1020°C prior to hot rolling. The solution treatments were designed such that all the calculated volume fraction of NbCN was taken into solution at 1300°C but only two-thirds was in solution at 1020°C, with the aim of grain refining the austenite. The material was controlled rolled over a range of finishing temperatures between 870 and 600°C. Mechanical and impact properties were determined and the microstructure observed by thin foil electron microscopy. Decreasing the finishing rolling temperature was found to increase the yield stress for both solution-treatments but good impact properties were only found for the 1020°C treatment. The variation in properties is explained in terms of the observed microstructure.
TL;DR: In this article, the influence of prior deformation of martenite at room temperature upon the subsequent mechanical response of the alloy at increasing degrees of metastability is described, and the experimental results indicate that the tensile strength, the mean work-hardening rate and the volume fraction of martensite transformed up to necking are primarily controlled by the temperature of deformation.
TL;DR: In this article, entrainment and immobilization of liquid by the particles can also account for the facts that the volume fraction of particles in a packed bed depends on particle size.
TL;DR: In this paper, the viscoelastic properties of dilute flocculated paraffin oil-in-water emulsions stabilized by 5% potassium laurate have been measured using a method based on oscillatory flow in small tubes.
TL;DR: In this paper, the deformation flow profile changed gradually from a parabolic to a W-shaped pattern as the volume fraction of the high-density polyethylenes (HDPE) component increased.
Abstract: The solid (crystalline) state coextrusion of two high-density polyethylenes (HDPE) having weight-average molecular weights (Mw) of 59,000 and 200,000 have been studied as a function of the geometrical arrangement and the volume fraction of the components. The extrusion rate increased nonlinearly with the volume fraction of the low-Mw, component. The rate was faster when the low-Mw, component was the core rather than the sheath in the initial cylindrical concentric billet. Thus the slow extrusion rate of high-Mw HDPE alone was increased up to ten times by coextrusion with a small fraction of the low-Mw, HDPE component in its center. Generally, the deformation flow profile changed gradually from a parabolic to a W-shaped pattern as the volume fraction of the high-Mw, component increased. However, the geometric arrangement of the two different Mw components also had a pronounced effect on the deformation. The deformation patterns showed that upon coextrusion the low- and high-Mw HDPE's were extruded at the same rate and extrusion draw ratio. The geometrical arrangement had no substantial effects on the tensile modulus and strength of the extrudates; i.e., they increased linearly with volume fraction of the high-Mw HDPE.
TL;DR: In this paper, the dependence of the maximum volume fraction of spherical particles, o max, of a slurry was related to absorption and immobilization of the liquid by the suspended particles.