Thinner Wires Research Articles

Thin Wire Casting Using Twin Wheel Caster Equipped with Horizontal Wheels

solidification, process shortening and energy saving. A twin-wheel caster equipped with two additional horizontal wheels was proposed to cast thin aluminum alloy wire at higher speed. In the proposed twin-wheel caster, a groove was machined on the lower wheel. Two small horizontal wheels were positioned between the molten-metal-pouring launder and the upper wheel to assist the solidification of poured molten metal and to prevent burr formation. The alignment of the horizontal wheel sensitively affected the occurrence of wire defects. An Al-1.2%Fe wire with a cross section of 6.2 mm2 was cast at 15 m/min. Thinner wires without burring could be cast at a speed higher than that of the twin-wheel caster without the horizontal wheels. The surface condition of the as-cast wire cast by the twin-wheel caster equipped with horizontal wheels was worse than that of the casting using the twin-wheel caster without horizontal wheels.

Strength and ductility of thin Cu wires

Abstract The stress– strain behavior of thin copper wires in the range 20 – 250 μm diameter and various purities (3N, 5N) have been investigated. The wires were subjected to a recrystallization heat treatment and tensile properties were determined. Tensile testing was performed using a microtensile testing machine equipped with a non-contacting laser-optical speckle correlation sensor adapted for high-resolution strain measurement. The fracture elongation of all specimens exhibited lower values than that of bulk Cu with a decreasing trend for thinner wires. High-purity wires with a pronounced bamboo structure showed a size dependence of the yield strength which increased with decreasing wire diameter. Surface topography and fracture surfaces of the specimens were examined. The microstructural investigations were performed to arrive at an understanding and interpretation of our experimental results.

Theoretical Investigation of the Effects of some Geometrical Parameters on the Performance of Wire-Plate Electrostatic Precipitator

Some geometric parameters affecting the performance of a wire-plate electrostatic precipitator (ESP) are investigated theoretically. A numerical model was built to investigate the influence of the discharge wire size, wire separation, collector plates spacing, and roughness factor on the ESP performance. The results show that thinner wires emit higher current than larger ones at the same applied voltage, which would be suitable for low voltage power supply to generate the desired current density at the collecting electrodes. The results also show that, as the discharge electrodes get closer, the corona gets suppressed, resulting in a diminished corona current flow. On the other hand, as the distance between electrodes increases, the total current density decreases, leading to a less efficient ESP performance. Narrow spacing between collector plates gives a better performance. With regard to the effect of the roughness factor, the results revealed that the emitted current is strongly affected by the wires physical conditions.

Development of 3D hollow woven fabrics with superior mechanical properties by using nitinol and steel wire core hybrid yarns

In this study, nitinol and steel wire core hybrid yarns were produced from wires having two different diameters and used as warp yarns to weave 3D woven fabrics in two different fabric constructions. The steel bars with two different diameters were placed into the gaps between fabric layers to create a hollow form after fabric production. The fabrics produced with cold-worked nitinol wire were exposed to heat treatments at high temperatures to provide them shape memory property according to data obtained from DSC analysis. Conventional textile fibers are not durable to these temperatures; for this reason, carbon fiber was used both as sheath material of hybrid yarns and additionally as warp and weft carbon fiber yarns. All yarn and fabric tests were carried out simultaneously to evaluate the mechanical properties of nitinol and steel wire core hybrid yarns, and wire-reinforced fabrics. Tensile tests were applied to all wire and hybrid yarn samples, DSC and DMA analyses were conducted for only heat-treated nitinol wires. Low-velocity impact, tensile and pull-out tests were applied to fabric samples. Reference fabrics with no wire were produced and evaluated by comparing with wire-reinforced samples to provide a point of comparison to the data from the mechanical properties of wire-reinforced 3D fabrics. The study's results were analyzed with regression analysis using the backward method, and the parameters such as wire type, wire diameter, and fabric gap width for optimum fabric production were determined. Data obtained from all mechanical tests demonstrate that fabric samples with steel wire, thinner wire, and narrow gaps have better results than others. The effect of wire thickness was also found the same for the nitinol wire. DMA analyses show that the thinner nitinol wire is better than, the thicker one. Finally, an innovative technique has been developed in this study to weave carbon fiber on a conventional automatic sample loom without fiber breakage by twisting PVA yarn around the wire core hybrid and twisted carbon fiber yarns.

State-of-the-art preclinical testing of the OMEGATM left atrial appendage occluder.

This study aimed to present a new approach of thorough preclinical testing of a novel left atrial appendage (LAA) occluder device. The development of a safe and effective LAA occluder has been shown to be challenging. The novel OMEGATM LAA occluder (Eclipse Medical, Ireland) was tested in a porcine model and three-dimensional (3D) human LAA models - this as a prelude to its first-in-human use. In a first series of in-vivo experiments, the OMEGATM LAA occluder was shown to have a satisfactory device biocompatibility in a porcine model. The design of the OMEGATM device was further refined and optimized following three more series of in-vivo experiments. The second generation OMEGATM device was designed with thinner wires, leading to a profile reduction. Based on in-vitro testing of different OMEGATM device sizes implanted at different depths in human three-dimensional (3D) LAA models, it could be determined that (1) the landing zone should be measured at a median depth of 12 mm from the LAA ostium; (2) the distal self-retaining inverted cup should have 10%-25% compression to minimize device embolization risk; and (3) the disc should be slightly inverted, i.e. pulled into the LAA, to promote complete LAA occlusion. The combined in-vivo and in-vitro testing resulted in an optimized pre-procedural planning of the first-in-human case treated with the OMEGATM device. This series of carefully planned in-vivo and in-vitro experiments allowed demonstration of the safety and efficacy of the OMEGATM LAA occluder. This approach of thorough preclinical testing of medical devices may reduce the risk of complications in first-in-human cases and may become the standard approach for device development and preclinical testing in the future.

The effect of wire size on high deposition rate wire and plasma arc additive manufacture of Ti-6Al-4V

Wire + arc additive manufacture (WAAM) is suitable for building large-scale components with high deposition rate. However, in order to further increase the deposition rate of Ti-6Al-4V to improve productivity and reduce manufacture costs without significantly compromising the quality, some fundamental process characteristics need to be investigated. In this paper, the effect of wire size on the limitation of deposition rate and bead shape in plasma arc additive manufacture was studied along with the process tolerance and melting characteristics, such as the effect of current and nozzle size on keyhole behaviour and the effect of wire feeding position on deposition process. The results show that with the same heat input the deposition rate increases linearly with the wire size due to the increasing melting efficiency. The bead geometry obtained with a thinner wire has a higher aspect ratio, which can be attributed to the difference in the distribution of the energy between wire and workpiece. The likelihood of keyhole increases with increasing current and decreasing nozzle size, and it can be mitigated by using thicker wires. The wire feeding position plays a significant role in determining the metal transfer mode, which has a great impact on the bead shape and process stability. Also, as the deposition rate changes thin wire is more sensitive to wire feeding position than thick wire in terms of metal transfer behaviour.

Capillary forces as a limiting factor for sawing of ultrathin silicon wafers by diamond multi-wire saw

Succeeding with ultrathin silicon wafer sawing by diamond multi-wire saw, is not only a matter of optimization; the challenges of thin wafer production and the capability limit have not yet been fully understood. In this work, we have seen that regular pairing of wires occurs when the wire-wire separation distance is reduced below some critical value. The wire pairing leads to wire jumps on the wire guide rolls, and if the run is not stopped, it leads to wire breakage. Moreover, it effectively obstructs the production of wafers thinner than the critical wire-wire distance.We suggest that the physical explanation to the observed limitations to ultrathin wafer sawing, by diamond multi-wire saw, is related to the capillary force acting on the wires due to the sawing liquid bridge connecting the wires. The hypothesis is supported by simplified mathematical modelling including capillary and spring forces between infinitely long, parallel wires. The calculations suggest that capillary forces are the main reason for wire pairing, and that wire pairing will occur when the wire distance is below some critical distance. This matches the observed, experimental behavior. The critical distance will vary with wafer saw design and operation.To succeed with cutting very thin wafers, we recommend using lower surface tension sawing fluid or even dry in-cut, to reduce the capillary forces and thus decrease the critical wire separation distance, and to reduce wire oscillations to decrease the probability of sub-critical wire-wire separation distance. To reduce the vibration amplitude, shorter distance between the wire guide rolls, thinner wires, and increased wire tension are suggested.

Effects of circuit inductance on electrical and shock wave characteristics at underwater wire explosion

Circuit inductance is an important parameter at underwater electrical wire explosion (UEWE) experiments as it closely relates to the energy deposition rate to the load wire. In this study, the circuit inductance was varied within a wide range from 1.55 μH to 93.2 μH by inserting inductive coils to study its effects on electrical and shock wave (SW) characteristics at UEWE. Experimental results showed that UEWEs using thinner wires were less affected by the increase of circuit inductance and the SW peak pressure several-cm away from the wire is not sensitive to the increase of circuit inductance if properly choosing the diameter of load wire: the maximum SW peak pressure obtained with varied diameter (constant energy storage and wire length) only saw a decrease of 30% as the circuit inductance increased by 60 times from 1.55 μH (0.3 mm diameter, 19 MPa) to 93.2 μH (0.2 mm diameter, 13 MPa). Hydrodynamic calculations were used to explain the experimental results. These results indicated that for a practical UEWE system, the energy storage can be far away from the load while keeping an acceptable loss of the capability of generating strong SWs, which greatly improves the flexibility of system designing for example by enabling much larger energy storage for certain harsh working environments.

Diameter-dependent thermal conductivity of ultrathin GaP nanowires: A molecular dynamics study

The diameter dependence of the thermal conductivity of nanowires is usually modeled using Matthiessen's rule, by putting the mean free path of phonons equal to the diameter $d$ of the nanowire. This results in a thermal conductivity $\ensuremath{\kappa}$ that decreases with decreasing $d$, due to the increase in boundary scattering. Recent molecular dynamics studies of heat transport in thin silicon nanowires have shown a nonmonotonic diameter dependence of $\ensuremath{\kappa}$, where a decrease with decreasing $d$ is followed by an increase to a value of $\ensuremath{\kappa}$ exceeding the bulk thermal conductivity. This increase of $\ensuremath{\kappa}$ was explained by an increase of the importance of hydrodynamic transport effects in the thinner wires, where the normal scattering by phonon-phonon interaction increases, but the Umklapp scattering decreases [Y. Zhou, X. Zhang, and M. Hu, Nano Lett. 17, 1269 (2017)]. Here, we study heat transport in thin nanowires of the compound semiconductor gallium-phosphide in the wurtzite crystal structure, using molecular dynamics simulations. A similar nonmonotonic $d$ dependence of $\ensuremath{\kappa}$ is found as in silicon nanowires, but with a minimum in $\ensuremath{\kappa}$ occurring at a much larger diameter of $d\ensuremath{\approx}8\phantom{\rule{0.16em}{0ex}}\mathrm{nm}$ instead of 2--3 nm.

Enhancement of Shock Wave Generated by Underwater Electrical Wire-Array Explosion at a Fixed Energy and Mass of Wire-Array

An energy-efficient method for further enhancing the shock wave generated by underwater electrical wire-array explosion at a fixed energy was developed. Based on the configuration of a cylindrical wire-array, the method was to replace one wire of 0.2-mm diameter with N thinner wires, while the total mass of these N wires was kept equal to the mass of that 0.2-mm wire. As the number of wires increased, the maximum wave pressure at the axis of the wire-array increased from 28 MPa for 1 wire of 0.2-mm diameter to about 90 MPa for 16 wires of 0.05-mm diameter. The shock wave generated by one single wire was proportional to 1/(N) <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1/2</sup> rather than 1/N, which should be the reason for the enhancement. The interaction of shock waves from each single wire was discussed. It might be roughly divided into two kinds, “non-overlapping” and “overlapping.” The “non-overlapping” occurred only in the wire-array with not more than four wires. While propagating toward the axis of the wirearray, the shock waves from the wires did not overlap even when they were close to the axis. The shock wave at the axis is simply the summation of the shock waves from all wires. In contrast, the “overlapping” occurred in the wire-array with not less than seven wires. The shock waves from the wires overlapped even when they were far from the axis. Due to the converging effect of shock waves, the shock wave at the axis is considerably lower than the summation of shock waves from all wires, especially when the number of wires is larger.

Intrinsic differences between thinner and thicker wires in NiTi SMA

The civil engineering equipment, such as the bridges, were located outside the laboratory equipment and were subject to the direct effect of the external temperatures. In moderate climates, the summer and winter temperatures vary between −10°C and 40°C, but in northern Europe or Canada, the cold temperatures can easily reach −50°C or lower. The temperature modifies the SMA behaviour by the action of the Clausius-Clapeyron thermodynamic equation. The analysis performed in this work focuses on the similarity, suitability and guaranteed behaviour of NiTi SMA wires with different diameters. In particular, the study establishes the effects of the summer-winter temperature variation on the SMA. It was found that the external temperature has a negative effect on the thinner wires in comparison with the valuable behaviour of thicker wires. The particular effects of the diameter are enhanced when the samples are submitted to strain-aging.

Intrinsic differences between thinner and thicker wires in NiTi SMA

The civil engineering equipment, such as the bridges, were located outside the laboratory equipment and were subject to the direct effect of the external temperatures. In moderate climates, the summer and winter temperatures vary between −10°C and 40°C, but in northern Europe or Canada, the cold temperatures can easily reach −50°C or lower. The temperature modifies the SMA behaviour by the action of the Clausius-Clapeyron thermodynamic equation. The analysis performed in this work focuses on the similarity, suitability and guaranteed behaviour of NiTi SMA wires with different diameters. In particular, the study establishes the effects of the summer-winter temperature variation on the SMA. It was found that the external temperature has a negative effect on the thinner wires in comparison with the valuable behaviour of thicker wires. The particular effects of the diameter are enhanced when the samples are submitted to strain-aging.

Opposed-Flow Flame Spread and Extinction in Electric Wires: The Effects of Gravity, External Radiant Heat Flux, and Wire Characteristics on Wire Flammability

Combustion of electric wires is the most probable cause of fire in human space activities. Therefore, the fire performance of electric wires in microgravity conditions must be thoroughly analyzed. This study investigates the opposed-flow flame spread and its limits in electric wires preheated by external radiation, under both normal gravity and microgravity, to understand their fire performance when exposed to external heat sources in such gravity conditions. The experiments were performed on low-density polyethylene (LDPE)-insulated copper (Cu) wires having an outer diameter of 4 mm and differing in core diameter (2.5 and 0.7 mm, corresponding to insulation thicknesses of 0.75 and 1.65 mm, respectively). Both standard and black LDPE insulations were used to study the effect of radiation absorption on the wire preheating and subsequent flame spread. The comparison of the flame spread limits revealed that the wire with the thicker Cu core was less flammable under both normal gravity and microgravity; in particular, its flammability further decreased in the case of microgravity, in contrast with thinner electric wires (~ 1 mm outer diameter), which exhibited higher flammability in the same gravity condition. These results suggest that different mechanisms, for thicker and thinner wires, determining the critical conditions to sustain flame spread under microgravity. This study provides valuable information about the fire performance of electric wires in space gravity.

Geometrically necessary dislocations induced size effect in the torsional stress relaxation behavior of thin metallic wires

Torsional stress relaxation experiments on thin copper wires are performed. A size effect is observed. That is a faster relaxation deformation arises in a thinner wire. As the wire diameter increases, the activation volume increases but the strain rate sensitivity decreases. A greater effect of geometrically necessary dislocations on the relaxation deformation accounts for the size effect. In a thinner wire, geometrically necessary dislocations undergo fewer obstacles to reach the wire center and then neutralize, causing a more rapid evolution of mobile dislocations.

Optical cages

We examine arrays of metal-mesh frameworks for their wide-band absorption. These take the form of quasi-crystal optical cages. While there are many plasmonic structures that exhibit lossy behavior, they tend to be narrow band. By defining a quality loss metric, L = A/Q, where A is the absorption coefficient and Q is the quality factor, we are able to show that all absorbers fall in the range L:[0,2]. Metastructures have L∼0.04 while in our case L∼0.35. An array of cages tends to concentrate the incoming radiation within each framework. An array of cage-within-cage funnels the radiation from the outer cage to its inner core even further raising the possibility for new applications. We report on two surprising outcomes: copper based frameworks are better than silver based, and larger cage opening (thinner wires) are more effective than smaller openings (thicker wires).

Trace of increasing dot size in porous silicon systems of same thicknesses

The present work enables the understanding of the porous system of porous silicon (PS) in terms of growth of dots and wires (quantum Si nanostructures) under certain conditions. When it comes to optical properties, PS should be recognized in terms of growth of the dots and wires instead of its porosity as ∼2–5 nm sized Si-nanostructures are responsible for luminescence. In present work, the photoluminescence (PL) spectra of PS samples of thickness 1 μm were used to estimate the percentage, average diameters and corresponding variances of dots and wires nanostructures by Singh and John (John-Singh) model. We have explicitly included the role of surface states on the fitting of John-Singh model. As a result, the plotted analytical curve revealed that an increase of current density, for fabricating the same thickness of the PS systems, results in the homogeneous formation of relatively thinner wires with a simultaneous growth of dots. It is a useful clue towards the fabrication of silicon quantum dots for photonic applications.

Size effects on uniaxial tension and multiaxial ratcheting of oligo-crystalline stainless steel thin wires

The uniaxial tensile and multiaxial ratcheting behaviors of oligo-crystalline 316L stainless steel thin wires of two diameters (190 and 90 μm) with less than 3.5 grains across diameter were experimentally investigated. The size effect of “thinner is stronger” was observed on the yield strength, though the ultimate tensile strength and elongation were lower in the thinner wire. Under six differently combined axial stress and shear strain cycling conditions, the ratcheting strains were all found to be relatively suppressed in the thinner wire, accompanied by enhanced shear stress flow. Moreover, unlike in bulk materials, the multiaxial ratcheting strain in both thin wires tended to be loading path independent in the cases with the same shear strain amplitude, axial mean stress and stress amplitude. The mechanisms of these size effects were analyzed to be related to the surface dislocation source limitation and strain gradient hardening.

In vitro measurement of the permeability of endovascular coils deployed in cerebral aneurysms

Background and purposeAneurysm recurrence is the primary limitation of endovascular coiling treatment for cerebral aneurysms. Coiling is currently quantified by a volumetric porosity measure called packing density (pd). Blood flow...

Dynamic strain aging during wire drawing and its effect on electrochemical behaviour

Second stage dynamic strain aging is observed during cold drawing of low carbon steel wire rods with higher free nitrogen content. The effect is prominent in thinner wires which have experienced higher strain and are thereby heavily stressed. Consequently, these severely deformed wires with higher nitrogen content are prone to early environmental degradation.

Uniform Deposition of Chemical Vapor Deposition Diamond Films on Slender Tungsten Wires

In the present study, high-quality chemical vapor deposition (CVD) micro-crystalline diamond (MCD) film was successfully deposited on the surface of the Φ0.5 mm×120 mm tungsten wire using a special designed graphitic jig for supporting the substrate and a two-step deposition procedure for guaranteeing the uniformity of as-deposited diamond film. It is proved that as-deposited film indeed presented much more uniform thickness than that obtained using a conventional jig described in the previous literature, and a very thick WC interlayer spontaneously formed between the substrate and the diamond film, which together with as-deposited MCD film have significant effects on mechanical properties of the wire. Generally speaking, the coated wire remains extremely high surface hardness of the MCD film and considerable toughness of the substrate, along with favorable film-substrate adhesion. It is recognized that these the coated tungsten wires have broad application prospects, but the technologies for depositing diamond films that are thick enough on even longer and thinner wires still need further investigation.