A Long Wavelength Model for Manufacturing of Continuous Metal Microwires by Thermal Fiber Drawing From a Preform

2017 ◽  
Vol 6 (1) ◽  
Author(s):  
Jingzhou Zhao ◽  
Xiaochun Li
Keyword(s):  
Interfacial Tension ◽  
Molten Metal ◽  
Capillary Number ◽  
Extensional Flow ◽  
Tension Stress ◽  
Core Diameter ◽  
Manufacturing Method ◽  
Long Wavelength ◽  
Thermal Drawing ◽  
Continuous Metal

Thermal drawing from a preform recently emerges as a scalable manufacturing method for the high volume production of continuous metal microwires for numerous applications. However, no model can yet satisfactorily provide effective understanding of core diameter and continuity from process parameters and material properties during thermal drawing. In this paper, a long wavelength model is derived to describe the dynamics of a molten metal micro-jet entrained within an immiscible, viscous, nonlinear free surface extensional flow. The model requires numerical data (e.g., drawing force and cladding profile) be measured in real time. Examination of the boundary conditions reveals that the diameter control mechanism is essentially volume conservation. The flow rate of molten metal is controlled upstream while the flow velocity is controlled downstream realized by solidification of the molten metal. The dynamics of the molten metal jet are found to be dominated by interfacial tension, stress in the cladding, and pressure in the molten metal. Taylor's conical fluid interface solution (Taylor, 1966, “Conical Free Surfaces and Fluid Interfaces,” Applied Mechanics, Springer, Berlin, pp. 790–796.) is found to be a special case of this model. A dimensionless capillary number Ca=2Fa/γA(0) is suggested to be used as the indicator for the transition from continuous mode (i.e., viscous stress dominating) to dripping mode (i.e., interfacial tension dominating). Experimental results showed the existence of a critical capillary number Cacr, above which continuous metal microwires can be produced, providing the first ever quantitative predictor of the core continuity during preform drawing of metal microwires.

scholarly journals Self-powered multifunctional sensing based on super-elastic fibers by soluble-core thermal drawing

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Mengxiao Chen ◽  
Zhe Wang ◽  
Qichong Zhang ◽  
Zhixun Wang ◽  
Wei Liu ◽  
...  
Keyword(s):  
Polymer Fibers ◽  
Elastic Fibers ◽  
Triboelectric Nanogenerator ◽  
Large Area ◽  
Manufacturing Method ◽  
Low Viscosity ◽  
Ion Movements ◽  
Self Powered ◽  
Thermal Drawing ◽  
Viscosity Polymer

AbstractThe well-developed preform-to-fiber thermal drawing technique owns the benefit to maintain the cross-section architecture and obtain an individual micro-scale strand of fiber with the extended length up to thousand meters. In this work, we propose and demonstrate a two-step soluble-core fabrication method by combining such an inherently scalable manufacturing method with simple post-draw processing to explore the low viscosity polymer fibers and the potential of soft fiber electronics. As a result, an ultra-stretchable conductive fiber is achieved, which maintains excellent conductivity even under 1900% strain or 1.5 kg load/impact freefalling from 0.8-m height. Moreover, by combining with triboelectric nanogenerator technique, this fiber acts as a self-powered self-adapting multi-dimensional sensor attached on sports gears to monitor sports performance while bearing sudden impacts. Next, owing to its remarkable waterproof and easy packaging properties, this fiber detector can sense different ion movements in various solutions, revealing the promising applications for large-area undersea detection.

scholarly journals Interfacial Tension Measurements in Microfluidic Quasi-Static Extensional Flows

Micromachines ◽  
2021 ◽  
Vol 12 (3) ◽  
pp. 272
Author(s):  
Doojin Lee ◽  
Amy Q. Shen
Keyword(s):  
Interfacial Tension ◽  
Microfluidic Device ◽  
Extensional Flow ◽  
Immiscible Fluids ◽  
Droplet Microfluidics ◽  
Channel Height ◽  
Deformation Model ◽  
Droplet Deformation ◽  
Extensional Flows ◽  
2D Model

Droplet microfluidics provides a versatile tool for measuring interfacial tensions between two immiscible fluids owing to its abilities of fast response, enhanced throughput, portability and easy manipulations of fluid compositions, comparing to conventional techniques. Purely homogeneous extension in the microfluidic device is desirable to measure the interfacial tension because the flow field enables symmetric droplet deformation along the outflow direction. To do so, we designed a microfluidic device consisting of a droplet production region to first generate emulsion droplets at a flow-focusing area. The droplets are then trapped at a stagnation point in the cross junction area, subsequently being stretched along the outflow direction under the extensional flow. These droplets in the device are either confined or unconfined in the channel walls depending on the channel height, which yields different droplet deformations. To calculate the interfacial tension for confined and unconfined droplet cases, quasi-static 2D Darcy approximation model and quasi-static 3D small deformation model are used. For the confined droplet case under the extensional flow, an effective viscosity of the two immiscible fluids, accounting for the viscosity ratio of continuous and dispersed phases, captures the droplet deformation well. However, the 2D model is limited to the case where the droplet is confined in the channel walls and deforms two-dimensionally. For the unconfined droplet case, the 3D model provides more robust estimates than the 2D model. We demonstrate that both 2D and 3D models provide good interfacial tension measurements under quasi-static extensional flows in comparison with the conventional pendant drop method.

Evolution and stationarity of liquid toroidal drop in compressional Stokes flow

2017 ◽  
Vol 835 ◽  
pp. 1-23 ◽  
Author(s):  
B. K. Ee ◽  
O. M. Lavrenteva ◽  
I. Smagin ◽  
A. Nir
Keyword(s):  
Cross Sections ◽  
Capillary Number ◽  
Initial Conditions ◽  
Extensional Flow ◽  
Building Blocks ◽  
Physical Parameters ◽  
Ambient Fluid ◽  
Medicinal Substances ◽  
Expansion Dynamic ◽  
Axisymmetric Disturbances

Dynamics of fluid tori in slow viscous flow is studied. Such tori are of interest as future carriers of biological and medicinal substances and are also viewed as potential building blocks towards more complex particles. In this study the immiscible ambient fluid is subject to a compressional flow (i.e., bi-extensional flow), and it comprises a generalization of our earlier report on the particular case with viscosity ratio$\unicode[STIX]{x1D706}=1$(see Zabarankinet al.,J. Fluid Mech., vol. 785, 2015, pp. 372–400), where$\unicode[STIX]{x1D706}$is the ratio between the torus viscosity and that of the ambient fluid. It is found that, for all viscosity ratios, the torus either collapses towards the axis of symmetry or expands indefinitely, depending on the initial conditions and the capillary number,Ca. During these dynamic patterns the cross-sections exhibit various forms of deformation. The collapse and expansion dynamic modes are separated by a limited deformation into a deformed stationary state which appears to exist in a finite interval of the capillary number,$0<Ca<Ca_{cr}(\unicode[STIX]{x1D706})$, and is unstable to axisymmetric disturbances, which eventually cause the torus either to collapse or to expand indefinitely. The characteristic dimensions and shapes of these unstable stationary tori and their dependence on the physical parametersCaand$\unicode[STIX]{x1D706}$are reported.

scholarly journals Drop formation in microfluidic cross-junction: jetting to dripping to jetting transition

2019 ◽  
Vol 23 (8) ◽  
Author(s):  
Nina M. Kovalchuk ◽  
Masanobu Sagisaka ◽  
Kasparas Steponavicius ◽  
Daniele Vigolo ◽  
Mark J. H. Simmons
Keyword(s):  
Interfacial Tension ◽  
Capillary Number ◽  
Continuous Phase ◽  
Flow Rate Ratio ◽  
Dispersed Phase ◽  
Flow Focusing ◽  
Jet Formation ◽  
Relative Contribution ◽  
Power Law Function ◽  
Dispersed Phases

AbstractThe regimes of drop generation were studied in a Dolomite microfluidic device which combined both hydrodynamic and geometrical flow focusing over a broad range of flow rates. A series of aqueous dispersed phases were used with a viscosity ratio between continuous and dispersed phases of close to unity. Surfactants were added to alter the interfacial tension. It was shown that the transition from dripping to jetting is well described by the capillary numbers of both the dispersed and continuous phases. Only the jetting regime was observed if the capillary number of the dispersed phase was above a critical value, whereas at smaller values of this parameter a jetting → dripping → jetting transition was observed by increasing the capillary number of the continuous phase. The analysis performed has shown that the conditions for a dripping to jetting transition at moderate and large values of the capillary number of the continuous phase can be predicted theoretically by comparison of the characteristic time scales for drop pinch-off and jet growth, whereas the transition at small values cannot. It is suggested that this transition is geometry mediated and is a result of the interplay of jet confinement in the focusing part and a decrease of confinement following entry into the main channel. The flow fields inside the jet of the dispersed phase were qualitatively different for small and large values of the capillary number of the continuous phase revealing the relative contribution of the dispersed phase flow in jet formation. The volume of the drops formed in the jetting regime increased as a power law function of the flow rate ratio of the dispersed to continuous phase, independent of the interfacial tension.

Effect of Interfacial Tension on Water/Oil Relative Permeability on the Basis of History Matching to Coreflood Data

2014 ◽  
Vol 17 (01) ◽  
pp. 37-48 ◽  
Author(s):  
Edwin Andrew Chukwudeme ◽  
Ingebret Fjelde ◽  
Kumuduni Abeysinghe ◽  
Arild Lohne
Keyword(s):  
Interfacial Tension ◽  
Relative Permeability ◽  
Capillary Number ◽  
History Matching ◽  
Water Saturation ◽  
Residual Water ◽  
End Effects ◽  
The Core ◽  
Rate Dependent ◽  
Phase Saturation

Summary The effect of interfacial tension (IFT) on the displacement of the nonwetting and wetting phases has been investigated by the use of simulations/history matching of flooding experiments. In surfactant flooding, a conventional assumption is to neglect the effect of capillary pressure (Pc) on measured two-phase properties. The methodology applied in this paper allows improved interpretation of experimental results by correcting for the influence of capillary end effects on the measured capillary desaturation curve (CDC) and on the estimated relative permeability (kr). Three fluid systems of different IFTs were prepared by use of a solvent system (CaCl2 brine/iso-octane/isopropanol) rather than a surfactant system with the assumption that both systems have similar flood behavior at reduced IFT. Three coreflood cycles, including multirate oil injection (drainage) followed by multirate water injection (imbibition), were carried out at each IFT in water-wet Berea cores. The kr functions corrected for capillary end effects were derived by numerically history matching the experimental production and pressure-drop (PD) history. A typical CDC is observed for the nonwetting phase oil, with a roughly constant plateau in residual oil saturation (ROS), Sor, below a critical capillary number (Ncc) and a declining slope above Ncc toward zero Sor. No influence of Pc was found for the nonwetting-phase CDC. The results from the displacement of the wetting phase formed an apparent CDC with a declining slope and no Ncc. Analyzing the wetting-phase results, we find that the wetting-phase CDC is not a true CDC. First, it is a plot of the average remaining water saturation (Sw) in the core which, in all the experiments, is higher than residual water saturation, Swr, obtained from Pc measurements. Second, we find that the remaining Sw is only partly a function of Nc. At low Nc, the water production (WP) is limited by capillary end effects. Rate-dependent WP observed with the high-IFT system is fully reproduced in simulations by use of constant kr and Pc. The remaining wetting-phase saturation at a low capillary number (Nc) is a result of the core-scale balance between viscous and capillary forces and would, for example, depend on the core length. At a higher Nc, the WP is found to be limited by the low kr tail, typical for wetting phases. However, we find that the kr functions become rate dependent at a higher Nc, and we assume that this rate dependency can be modeled as a function of Nc. The remaining wetting-phase saturation at a higher Nc would then be a function of Nc and the number of pore volumes (PVs) injected. The observed Nc dependency in the flow functions indicates a potential for the accelerated production of the wetting phase by use of surfactant. Assuming that the results obtained here for the wetting phase also apply to oil in a mixed-wet system, it is strongly recommended to evaluate the effect of both Pc and Ncc when designing a surfactant model for a mixed-wet field.

scholarly journals Scalable Manufacturing of AgCu40(wt %)–WC Nanocomposite Microwires

2018 ◽  
Vol 6 (3) ◽  
Author(s):  
Zeyi Guan ◽  
Injoo Hwang ◽  
Shuaihang Pan ◽  
Xiaochun Li
Keyword(s):  
Stir Casting ◽  
Metallic Materials ◽  
Casting Method ◽  
Manufacturing Method ◽  
New Class ◽  
Dispersion Mechanism ◽  
Annealed Copper ◽  
Thermal Drawing ◽  
First Time ◽  
Drawing Method

Nanoparticle reinforced metals recently emerge as a new class of materials to empower the functionality of metallic materials. There is a remarkable success in self-incorporation of nanoparticles to bulk metals for extraordinary properties. There is also a strong demand to use nanoparticles to enhance the performance of metallic microwires for exciting opportunities in numerous applications. Here, we show for the first time that silver–copper alloy (AgCu) reinforced by tungsten carbide (WC) (AgCu40 (wt %)–WC) was manufactured by a stir casting method utilizing a nanoparticle self-dispersion mechanism. The nanocomposite microwires were successfully fabricated using thermal drawing method. By introducing WC nanoparticles into bulk AgCu40 alloy, the Vickers microhardness was enhanced by 63% with 22 vol % WC nanoparticles, while the electrical conductivity dropped to 20.1% International Annealed Copper Standard (IACS). The microwires of AgCu40–10 vol % WC offered an ultimate tensile strength of 354 MPa, an enhancement of 74% from the pure alloy, and an elongation of 5.2%. The scalable manufacturing method provides a new pathway for the production of metallic nanocomposite micro/nanowires with outstanding performance for widespread applications, e.g., in biomedical, brazing, and electronics industries.

scholarly journals Effects of a surfactant monolayer on the measurement of equilibrium interfacial tension of a drop in extensional flow

2009 ◽  
Vol 333 (2) ◽  
pp. 570-578 ◽  
Author(s):  
Andrés González-Mancera ◽  
Vijay Kumar Gupta ◽  
Mustapha Jamal ◽  
Charles D. Eggleton
Keyword(s):  
Interfacial Tension ◽  
Extensional Flow

Defect Formation Mechanism and Influence of Processing Parameters on Surface Quality of Copper Clad Steel Composite Wires Prepared by Core-Cladding Continuous Casting

2017 ◽  
Vol 898 ◽  
pp. 1183-1189
Author(s):  
Wei Yu Wu ◽  
Xue Feng Liu ◽  
Feng Yi
Keyword(s):  
Continuous Casting ◽  
Surface Quality ◽  
Molten Metal ◽  
Surface Defects ◽  
Defect Formation ◽  
Formation Mechanisms ◽  
Core Diameter ◽  
Melt Temperature ◽  
Clad Steel ◽  
Composite Wires

Copper clad steel (CCS) composite wires with the carbon steel core diameter of 8 mm and copper cladding thickness of 1 mm were prepared by core-cladding continuous casting method under argon protection. The effects of melt temperature, molten metal height and drawing velocity on the surface quality were investigated. The formation mechanisms of the surface defects were discussed. The results showed that CCS wires with good surface quality could be continuously fabricated at a melt temperature of 1120 to 1200°C, a molten metal height of 2 to 4 cm and a drawing velocity of 10 to 30 mm/min. Raising the melt temperature, increasing the molten metal height or decreasing the drawing velocity is in favor of improvements in the surface quality. Insufficient supplement of liquid copper during solidification shrinkage resulted in surface dimple. Transverse hot cracking and exposed steel defect appeared because the frictional force between cladding metal and mold was larger than the tensile strength of cladding metal under high temperature.

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