Metal Disk Research Articles

In situ measurements of electrical resistivity of metals in a cubic multi-anvil apparatus by van der Pauw method.

On the basis of the van der Pauw method, we developed a new technique for measuring the electrical resistivity of metals in a cubic multi-anvil high-pressure apparatus. Four electrode wires were introduced into the sample chamber and in contact with the pre-pressed metal disk on the periphery. The sample temperature was measured with a NiCr-NiSi (K-type) thermocouple, which was separated from the sample by a thin hexagonal boron nitride layer. The electrodes and thermocouple were electrically insulated from each other and from the heater by an alumina tube as well. Their leads were in connection with cables through the gap between the tungsten carbide anvils. We performed experiments to determine the temperature dependence of electrical resistivity of pure iron at 3 and 5 GPa. The experiments produce reproducible measurements and the results provide an independent check on electrical resistivity data produced by other methods. The new technique provides reliable electrical resistivity measurements of metallic alloys and compounds at high pressure and temperature.

Evaluation of surface treatments by self glaze, over glaze and a polishing agent on the porcelain surface modified with diamond rotary instrument-an in vitro study

The purpose of this study is to evaluate effect of a) Self glaze b) Over glaze and c) Polishing on porcelain surface which is subjected to grinding with a diamond rotary instrument. To test this theory 40 ceramic fused to metal disc samples were fabricated. The ceramic material used was Ivoclar Dsign. The discs were of 10mm X 3mm of which 2mm is metal substructure and 1mm is of porcelain. The specimens were divided into four groups of 10 samples each. The first group was left as fired or unglazed. The remaining three groups were subjected to surface modification with sintered diamond bur at 15000 rpm per minute with even pressure. Each of the three groups was treated with diamond polishing paste, self glaze and overglaze respectively. The surface of all the four groups were evaluated under optical microscope and scanning electron microscope. Optical microscope observation revealed that Group-I (as fired) had the surface of the specimens appearing to be pitted, rough with irregularities and there was no evidence of surface cracks. Group II (polished with diamond bur) had surface appeared to be very smooth.

Field Enhancement in Nanoparticles Due to IR Vortex Beams

In this report we present our study of interaction of light carrying OAM (Orbital Angular Momentum) with nanometric metallic discs. Plasmonic effects are known to give rise to high local field enhancement factors in gold nano-discs. These high intensities near fields have found use in a wide variety of imaging and detection applications. The local field enhancement factor near the surface of the disc was calculated numerically using finite element method using the Comsol package. We report a significant increase in the local field enhancement factor for light beams carrying OAM compared to Gaussian beams which are attributed to Localised Surface Plasmon Resonances (LSPR). Such large enhancements in the field can be immensely useful in the field on near field microscopy and electron generation.

Mechanospray Ionization MS of Proteins Including in the Folded State and Polymers.

Mechanospray ionization (MoSI) is a technique that produces ions directly from solution-like electrospray ionization (ESI) but without the need of a high voltage. In MoSI, mechanical vibrations aerosolize solution phase analytes, whereby the resulting microdroplets can be directed into the inlet orifice of a mass spectrometer. In this work, MoSI is applied to biomolecules up to 80 kDa in mass in both denatured and native conditions as well as polymers up to 12 kDa in mass. The various MoSI devices used in these analyses were all comprised of a piezoelectric annulus attached to a central metallic disk containing an array of 4 to 7 μm diameter holes. The devices vibrated in the 100-170 kHz range to generate a beam of microdroplets that ultimately resulted in ion formation. A linear quadrupole ion trap (LIT) and orbitrap mass spectrometer were used in the analysis to investigate higher mass proteins at both native (folded) and denatured (unfolded) conditions. MoSI native mass spectra of proteins acquired on the orbitrap and LIT instrument demonstrated that proteins could remain intact and in a folded state. In the case of native MS of holomyoglobin, the intact folded protein remained mostly bound noncovalently to the heme group, and typically, the spectra showed reduced loss of the heme group by MoSI as compared to ESI. In both non-native and native protein analyses examples, broader often multimodal distributions to lower charge states were observed. When using the LIT instrument, a significant increase in the relative abundance of dimers was observed by MoSI as compared to ESI. The softness of the MoSI technique was evidenced by the lack of fragmentation, the formation of dimers as also noted by others ( J. Mass Spectrom. 2016, 424-429) and under native conditions, the retention of proteins in one or more presumed folded structures and for holomyoglobin the high retention of the heme group. When analyzing polyethylene glycol (PEG) and polypropylene glycol (PPG), MoSI also generated a broader distribution to lower charge states than ESI. By using the improved separation of peaks at lower charge states and all the charge states available, MoSI data should provide an improved ionization method to obtain more accurate mass and dispersity values for some polymers.

An Analysis of Selected Technological Parameters’ Influences on the Tribological Properties of Products Manufactured Using the FFF Technique

This study investigates how layer deposition in printing 3D models made of polyetherimide (PEI) using the fused filament fabrication (FFF) technique affects resistance of these models to abrasive wear. Samples made by additive manufacturing with different setting of build orientation and path generation strategy of extruded fibers were used in the experiment. The experiments were conducted on a tribometer according to the ASTM G65-16 standard. The friction force, normal force, and temperature in the contact area during the tribometer operation were measured using a strain gauge sensor. The tribometer allowed us to perform the tribological experiments using a rubber-coated or a metal disc without a lubricant in the so-called “dry” operation. Following the ASTM G65-16 standard, a rubber-coated disc and Fe3Al2 (SiO4)3 garnet abrasive were used for the wear resistance tests. The analysis of experimental data showed correlations among orientation selection, the strategy of layer deposition by the FFF technique, and the surface life in terms of abrasive wear. The results of this research also showed the suitability of the chosen building orientation and deposition strategy for part production by additive manufacturing, depending on the required tribological properties, such as the coefficient of friction (yield path) and wear behavior. Based on the results of the study, it is concluded that continuity of wear and friction force depends on the path traveled under the model production orientation. The size of wear (material loss) ranged from 0.451–0.809%. It was shown that the weight loss of the sample under loading was greater, on average, with the chosen fiber orientation strategy in the Z direction than in the X direction.

Inline Quasi-Elliptic Bandpass Filter Based on Metal 3-D Printing Technology

This article presents a novel waveguide loaded air slots’ resonator (WLASR) comprised of a surrounding metal box and inserted metal disk with etched air slots. The proposed WLASR exhibits a comparable unloaded quality factor ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$Q_{\mathrm {u}}$ </tex-math></inline-formula> ) to the coaxial resonator and allows controlling the electric and magnetic couplings separately. These attractive characteristics were first deployed to design a four-pole inline electrical–magnetic mixed-coupling bandpass filter centered at 2.82 GHz with a fractional bandwidth of 6.73% and two controllable transmission zeros (TZs) located at 2.65 and 2.98 GHz, respectively. Direct metal 3-D printing technology was utilized to manufacture the prototype. The measured results were auspicious for the first demonstrated 3-D printed prototype. Hence, two six-pole filters with multiple TZs, more compact sizes, higher <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$Q_{\mathrm {u}}$ </tex-math></inline-formula> , and improved shape were designed. For experimental validation, one of them was printed with only two pieces. The measured results agreed well with the simulated ones.

Using an Innovative Mass Spectrometer and Non-Matrix–Matched Reference Materials to Quantify Composition of Metal Disks and Powders

This work demonstrates a new analytical technique and its quantification capabilities on a set of disparate metal samples. The laser ablation laser ionization time-of-flight mass spectrometer (LALI-TOF-MS) combines a dual-laser ionization system with a TOF mass analyzer for rapid, high-sensitivity elemental characterization of any solid material. To demonstrate the instrument’s quantification capabilities, nine different reference materials were analyzed. One solid and one powder reference material were then treated as “unknowns,” and quantified using calibration curves generated from the remaining reference materials. Despite being generated from reference materials of various matrices, elemental calibration curves are linear with an average R2 value of 0.96, even for elements that span several orders of magnitude in concentration range. For all elements quantified, results match the certified values of the “unknown” within the margins of error.

Boundary Element and Sensitivity Analysis of Anisotropic Thermoelastic Metal and Alloy Discs with Holes.

The main aim of this paper was to develop an advanced processing method for analyzing of anisotropic thermoelastic metal and alloy discs with holes. In the boundary element method (BEM), the heat impact is expressed as an additional volume integral in the corresponding boundary integral equation. Any attempt to integrate it directly will necessitate domain discretization, which will eliminate the BEM’s most distinguishing feature of boundary discretization. This additional volume integral can be transformed into the boundary by using branch-cut redefinitions to avoid the use of additional line integrals. The numerical results obtained are presented graphically to show the effects of the transient and steady-state heat conduction on the quasi-static thermal stresses of isotropic, orthotropic, and anisotropic metal and alloy discs with holes. The validity of the proposed technique is examined for one-dimensional sensitivity, and excellent agreement with finite element method and experimental results is obtained.

Air entrained into viscous liquid by a disk: Confinement induced suppression of breakup

When a solid object falls into a bath of viscous liquid due to gravity with zero initial velocity, air can be entrained into the viscous liquid with the solid. We study such an air entrainment by a metal disk falling in the direction perpendicular to its axis in a confined space. We previously reported that the entrained air is extended and forms a thin sheet, which finally detaches from the disk with a topological change: The extended air breaks up into two parts, after which the lower part becomes a small bubble and the upper part starts retracting upwards [Phys. Rev. Fluids 3, 054004 (2018)]. In the present paper, we further confined the air sheet using thinner disks, to surprisingly find a complete suppression of a topological change: The entrained air detaches from the disk without breakup (i.e., without creating a small bubble) but with forming, instead of a sheet, an elliptic corn at the tip. The physical origin of the confinement induced suppression of breakup is discussed from the viewpoints of the inversion of curvature of an air-liquid interface and the movement of the contact line. Near the corn-forming detachment, three length scales characterizing the dynamics are all proportional to a single characteristic length as in the previous sheet-forming case, which leads to a fixed aspect ratio for the elliptic corn in the present case. The characteristic scale satisfies a simple scaling law, which is different from the previous sheet-forming case, and governs the self-similar dynamics near the detachment point. The present corn-forming case provides a remarkable scenario for the self-similar dynamics discussed in various fields such as statistical physics, applied mathematics, and hydrodynamic topology transitions.

High virucidal potential of novel ceramic-metal composites fabricated via hybrid selective laser melting and spark plasma sintering routes.

In this work, we combine selective laser melting (SLM) and spark plasma sintering (SPS) to fabricate new materials with high virucidal potential. Various bioactive disc-shaped ceramics, metal alloys, and composites were fabricated and tested against bacteriophage Phi6—a model system for RNA-enveloped viruses. We prepared silver-doped titanium dioxide (TiO2 + 2.5‒10% Ag), copper-doped titanium dioxide (TiO2 + 2.5‒10% Cu), Cu2NiSiCr, and Cu15Ni8Sn composite materials (metal lattices filled with ceramics). The virucidal tests of the ceramic and metal powders were performed in buffered suspensions, while the surfaces of the discs were tested by swabbing. The results show that the virus titer on the TiO2 + 10% Ag ceramic and CuNi2SiCr metal discs decreased by 4 logs after 15 min of exposure to the surfaces compared to the control ceramic and steel discs. We show that SLM 3D printed pre-alloyed CuNi2SiCr filled with bioactive TiO2 + 10% Ag nanopowders and sintered by the SPS process combines the simplicity of printing with the strength and virucidal properties of Ag and Cu materials. The proposed new virucidal materials were also used for the fabrication of prototype elevator buttons.

How to Reduce the Design of Disc-Shaped Heat Exchangers to a Zero-Degrees-of-Freedom Task

The continuous quest for improving the performance of heat exchangers, together with ever more stringent volume and weight constraints, especially in enclosed applications like internal combustion engines and electronic devices, has stimulated the search for compact, high-performance units. One of the shapes that has emerged from a vast body of research is the disc-shaped heat exchanger, in which the fluid to be heated/cooled flows through radial—often bifurcated—channels carved inside a metallic disc. The disc in turn exchanges thermal energy with the hot/cold source (the environment or another body). Several studies have been devoted to the identification of an “optimal shape” of the channels: most of them are based on the extremization of some global property of the device, like its monetary or resource cost, its efficiency, the outlet temperature of one of the fluids, the total irreversibility of the process, etc. The present paper demonstrates that-for all engineering purposes there is only one correct design procedure for such a heat exchanger, and that if a few basic rules of engineering common sense are adopted, this procedure depends solely on the technical specifications (type of operation, thermal load, materials, surface quality): the design in fact reduces to a zero-degree of freedom problem. The procedure is described in detail, and it is shown that a proper application of the constraints completely identifies the shape, size and similarity indices of both the disc and the internal channels. The goal of this study is to demonstrate that-in this, as in many similar cases-a straightforward application of prime principles and of diligent engineering rules, may generate “optimal” designs: these principles guarantee a sort of “embedded optimality”.

Stochastic finite element analysis of composite cycloidal propeller blade during crash-stop ship maneuver

This article quantifies uncertainty in the dynamic responses of marine cycloidal propeller (MCP) blade by Stochastic Finite Element Method (SFEM) during crash-stop ship maneuver. Stopping a ship in an emergency is known as crash-stop astern maneuver. A MCP contains a horizontal circular metallic disc on which six aerofoil blades are hung vertically. All blades are made up of carbon fiber-reinforced composite laminates. Uncertainty in ship speed and composite material properties are propagated to find out the statistical response of natural frequencies, displacement, and stresses on the blade. SFEM is a combination of Stochastic Response Surface Method (SRSM) and Finite Element Method (FEM). SRSM is a collocation-based non-intrusive polynomial chaos expansion to transform any random distribution into a stochastic response surface equation (surrogate model). During ship maneuvering motion, the whole unit rotates about a vertical axis at the centre. For each rotation of the disc, all blades undergo periodic oscillations. The SRSM for uncertainty propagation is computationally more efficient than the standard Monte Carlo Simulation (MCS) technique without compromising the accuracy of the results. It is observed that uncertainty in vibration responses of MCP blade is significant and worth study.

Augmented Depolarizing Scatterer Based on Resonant Elements for Polarimetric Radar Calibration

A 3-in-1 depolarizing circular scatterer for the polarimetric radar calibration is proposed in this paper. The proposed scatterer is low cost, compact, planar circuit, and well suited for the radar operating in a compact range, for example, chipless RFID technology. By the virtue of its circular shape, the rear side of the proposed scatterer acts as a metallic disk with strong co polarization backscattered signals. The front side is composed of eight resonant dipoles which make it nondepolarizing and depolarizing scatterers at the inclination of 0° and 45°, respectively. The features of proposed circular scatterer are tested as reference calibration objects for single antenna based polarimetric radar calibration techniques. Two test objects are utilized: a dihedral tilted at 45° and a depolarizing multi resonant planar structure commonly called chipless RFID tag. The performance of proposed circular scatterer is also compared with the standard reference calibration objects: a metallic disk and a dihedral tilted at 22.5°. The performance of proposed circular scatterer is comparable to the standard reference calibration objects for the calibration techniques (namely Type 1 and Type 2). The proposed scatterer is potentially tolerant of displacement up to 1 cm and misalignment equals 2°.

Single Waveguide Feed Omnidirectional and Circularly Polarized Transceiver Waveguide Slot Antenna for Satellite Communication Applications

In this study, an omnidirectional and circularly polarized transceiver antenna, which can be used in simultaneous operations over transmit (TX) and receive (RX) channels for telemetry, tracking, and command (TTC) applications on the space segment of satellite communication, is proposed. The radiation and feed parts of the antenna consist of waveguide structures for high power necessity in transmit (telemetry) section. The radiation part includes two different sections of rotationally symmetric slotted arrays on circular waveguide, and radially outward metallic disks to improve omnidirectionality and circular polarization. The feed part contains a dual-band mod converter from rectangular TE10 mode to circular TM01 mode for symmetric field excitation over slots where the input of the converter is the standard rectangular waveguide. The design, simulation, and measurement results of the antenna are shown over a 3D printed prototype at Ku-band with center frequencies of 12 GHz and 14.25 GHz for TX and RX, respectively. With thin slots in telemetry section and thick slots in telecommand section, measured bandwidths for TX and RX frequencies are obtained approximately as 200 and 450 MHz, respectively. While TX band with maximum 3 dB gain variation over azimuth, maximum 3 dB axial ratio and minimum −3 dBi gain over 70° elevation beamwidth has relatively better performances at the expense of narrow bandwidth, RX band has maximum 3.5 dB gain variation over azimuth, maximum 4 dB axial ratio and minimum −6 dBi gain over 55° elevation beamwidth at the expense of wide bandwidth.

Forming characteristics and mechanism of double-roll rotary forging for large-diameter and thin-walled metal discs

Double-roll rotary forging is an emerging plastic forming technology based on rotary forging. Owing to the advantages of labor saving, small eccentric load, low noise and vibration, good uniformity, high surface quality, and material saving, it is very promising for fabrication of large-diameter thin-walled disc. To date, a few relevant researches on the double-roll rotary forging technology of large-diameter thin-walled metal discs have been reported, and the forming mechanisms and process of disc workpieces remain uninvestigated. Herein, a 3D rigid-plastic finite element model (FEM) is established to simulate the fabrication process of large-diameter thin-walled disc; four geometric features appear in the forming process: “mushroom” shape, “upper drum” shape, “drum shape” shape, and “lower drum” shape. Equivalent stress, equivalent strain, and temperature field of these four geometric shapes are analyzed, and the forming mechanism of these four geometric shapes is revealed. The reliability and accuracy of FEM are verified through experiments, and the four geometric shape features occur in the process are consistent with the simulation. The research results provide valuable guidelines for better understanding of double-roll rotary forging for the fabrication of large-diameter thin-walled discs.

Hypervelocity impact cratering on 5052-aluminum-alloy targets by flat-head cylindrical impactors of multipartite structure

In the present work, a series of hyper-velocity impact experiments was conducted on targets of aluminum alloy (A5052-H112) block using flat-head cylindrical impactors of plastic/metal/plastic multipartite structure, and the effects of the structure and the impact velocity on the shape of impact craters were investigated. The cylindrical impactors were composed of a front sabot of polycarbonate, an inner metal disk and a rear sabot of high-density polyethylene, polycarbonate or nylon 6. The metal disk was made of 2024-T4 aluminum alloy, Ti-6Al-4 V titanium alloy, or tough-pitch copper. The difference in the material composition together with the impactor's length-to-diameter ratio of 0.5 to 1.2 brought the difference in an averaged density of 1.0 to 2.1 g/cm3. The impact velocity ranged from 5.8 to 7.9 km/s. The cross sections of impact craters obtained were represented hemispherical in the bottom area, because the curvature of the crater bottom wall was regressed well with the radius of a circle arc fitting the bottom wall. Regression equations to reproduce the crater variables of penetration depth, diameter, volume and bottom-wall curvature were found using multiple-regression analysis as the product of powers of the impactor's variables of velocity, averaged density and length. Each equation had high reproducibility for its corresponding crater variable.

Numerical and Experimental Studies on Hydro-Forming of a Thin Metallic Disc

This paper deals with the hydro-forming of a flat thin metallic disc to achieve a forward domed disc which will be subsequently adopted to manufacture a rupture disc. The plastic deformation induced by the hydraulic energy is numerically simulated through an isotropic hardening plasticity model using a non-linear explicit finite element analysis (FEA). The variation in disc’s central deformation, thickness, equivalent plastic stress and equivalent plastic strain with respect to the applied hydraulic pressure are determined from FEA simulations. The hydro-forming setup is then designed and manufactured, and the metallic disc is experimented under hydro-forming process. The reduction in thickness due to stretching of the thin disc is evaluated from experiment and simulation and a close agreement is found. This research attempt helped in finalizing the hydro-forming fluid pressure, the feasibility and the accuracy of practically achieving the desired geometry of the metallic disc. The near-fixidity effects on abrupt variation in sheet thickness and plastic strain are well captured through simulations which are very difficult to be studied through hydro-forming experiments.

Biotribometer for Assessment of Cell and Tissue Toxicity of Orthopedic Metal Implant Debris.

A novel approach to address the clinical issue of cell response to wear and corrosion debris from metal orthopedic implants consists of combining cell culturing with wear and corrosion debris generation. A biotribometer equipped with a three-electrode electrochemical chamber operates inside a CO2 incubator. Cells are cultured at the bottom of the chamber. A ceramic ball (hip implant head) is pressed against a metal disc under a constant load, and set in reciprocating rotation. An anodic electrochemical potential can be applied to a metal disc for accelerated corrosion conditions, or the free potential may be monitored.Measurements of gravimetric and volumetric material loss of the metal disc postwear provide quantitative information that can be put in relation to biological assays (e.g., cell viability and secretion of proinflammatory cytokines). This approach allows for the comparison of candidate metals potentially undergoing tribocorrosion in clinical use. The approach allows to identify the effect of any metastable debris, likely active in vivo.

Исследование широкополосного компактного излучателя этажерочного типа

Simulation has been carried out and its results of calculation of the “shelf” type emitter have been presented. The design of this emitter consists of two metal disks mounted on supports, one of which is located on a dielectric substrate. The layout of the developed emitter is investigated. Measurements of KU, SWR, DN and CE of the manufactured model were carried out. The developed radiator is not inferior to the well-known analogues of emitter used as part of multibeam antennas in terms of REC, and also has advantages over them, namely a smaller vertical overall dimension, which is one of the most important criteria when choosing the type of radiator.

Spectrophotometric comparison of two porcelain systems, VMK master and VM13 with the VITA 3D-master shade guide (An in vitro study)

Accurate shade matching of metal-ceramic restorations with natural teeth is one of the most challenging aspects of dental restorations and esthetic dentistry. The aim of this study was to evaluate of the color parameters of two types of porcelain systems VMK Master and VM13 porcelain with VITA 3D-master shade guide. In this in vitro study a total of 56 metal discs (10 mm diameter and 2 mm thickness) were fabricated. Each of the disks was veneered with porcelain (Vita Zahnfabrik, Bad Sackingen, Germany) of the VITA shade. The discs were randomly divided into four groups (2M2 and 3M2 from VM13, 2M2 and 3M2 from VMK master) of 14 (n = 14). The spectrophotometer was used for taking color measurements based on the numerical color data of the CIELAB color system. Data analysis was performed by t-test (P < 0.05). Comparison of color parameters in different porcelain showed that the type of porcelain caused a significant difference in color parameters (L, a, and b) (P < 0.05). The degree of translucency (L*) or glaze of VMK porcelains was higher than VM13, but the parameters a* and b* were higher in VM13 porcelains than VMK (P < 0.05). Furthermore, the color difference of two porcelain in 2M2 (1.63 ± 0.84) and 3M2 (1.71 ± 0.96) shades was within the acceptable clinical limit. Considering the total color difference (ΔE), there were no significant differences between the ΔE values produced by any of shades (P > 0.05). In the present study, the spectrophotometric analysis revealed that the porcelain shade type causes a change in the color parameters, but the color difference between two porcelains VMK and VM13 is within the acceptable range of clinical color. Therefore, both porcelain systems with 2M2 and 3M2 shades are suitable for enhancing the results of restorative dentistry.