Loose Metal Research Articles

Flint arrowhead from a hoard in Papowo Biskupie, Chełmno district: comments on the discussion on the sacral function of lithic artefacts from the turn of the Iron Age

The article presents a flint arrowhead from Papowo Biskupie, Chełmno district. Hoards from this place and many loose metal finds are interpreted as votive offerings deposited in the water. Numerous objects made in bronze are accompanied by abundant non-cremated human bones unearthed there. The archaeological site is dated back to a period from about 1000 to 400 BC. A traceological analysis of the flint arrowhead showed that it had never been used, and that it found its way into one of the hoards on purpose as an element of a set of many artefacts that were deposited with in a birch bark container. Therefore, it probably served a purpose similar to that attributed to flint artefacts discovered in Lusatian-culture cremation graves. The provenance of the arrowhead can be determined in the context of Scythian-style ornaments that were reaching Kuyavia and Chełmno Land, as they have been found more and more often in the Lusatian culture in the area of Tarnobrzeg.

Sheet Metal Forming Analysis of Aluminium Alloy AA6061 using |Altair INSPIRE Form Simulation

Altair INSPIRE Form is a computer simulation developed for designing and modelling sheet metal forming processes. Within the modules, the design and formability prediction can be simulated and optimized. Thus, this study focuses on analysing the formability of sheet metal Aluminium alloy AA6061 by simulating numerically a multistage forming of an end-wall process where the material properties and process parameters gained from the literature were used as input. The geometrical model was validated by comparing its formability with the literature that was simulated by Altair HyperForm. Then, to statistically analyse the influence of forming parameters on formability, Analysis of Variance (ANOVA) was applied with the design of experiment approach using the Response Surface Methodology (RSM). The simulation results observed similar strain rate distributions between Inspire Form and HyperForm under a safe forming process. For the formability of Aluminium alloy AA6061, loose metal zones with wrinkles, excessive thinning up to 23.13%, and the maximum equivalent stress at 414.6 MPa were expected to be generated. These findings clearly explained that forming parameters such as blank holder force and punch velocity have to be carefully controlled for this ductile material. The ANOVA shows a significant influence of coefficient friction and punch velocity on thinning percentages. The likelihood of tearing to form at a higher thinning percentage and its appearance was observed in the Forming Limit Diagram which evaluates its formability. The validation of optimized parameters by simulation work is concluded to be successful as no fracture appeared in this simulation with a small percentage error at 2.19% between the simulation and the predicted value.

Electrodepostion of compact cadmium deposits in the non-aqueous ethylene glycol solution modified with ethanol

Electrodepostion of compact cadmium deposits in the non-aqueous ethylene glycol solution modified with ethanol

Enhanced performance of pinned metal foam heat sinks with dielectric coolant – A pore-scale numerical study

Enhanced performance of pinned metal foam heat sinks with dielectric coolant – A pore-scale numerical study

Failure analysis of convection section tube in an ethylene cracking furnace due to metal dusting

Failure analysis of convection section tube in an ethylene cracking furnace due to metal dusting

Perencanaan Perawatan Mesin Nail Making Machine Untuk Meminimasi Adanya Downtime di CV. XYZ

CV. XYZ is a manufacturing company that produces nails and barbed wire. Thedestruction of nail making machines or (nail making machines), resulting in clock stops (downtime and delay) in the production process which results in machine performance becoming less effective and efficient. Effectiveness in the production process needs to be supported by maintenance and maintenance management on the machine for that effective steps are needed in machine maintenance to be able to overcome and prevent these problems. This study conducted a literature study using books on Care Management, RCM Method, FMEA Method, LTA Method, and journals related to care management and also RCM Method. Maintenance intervals of critical components or components damaged 6 times a year with a maintenance time interval of 281 hours. While the side shaft components are damaged 4 times in one year with a maintenance time interval of 282 hours. Maintenance activities that need to be carried out to reduce failures in crank shaft components with the type of damage to the exhausted bearing lubricant need to be carried out schedule restoration task maintenance, the type of loose bearing damage needs to be carried out schedule discard task maintenance, and the type of loose or broken arm connection damage needs to be done schedule discard task. In side shaft components with broken types of metal handlebar connection damage, it is necessary to carry out schedule discard task maintenance, for damage to worn wire feeder loads, it is necessary to carry out schedule restoration task maintenance, and for loose metal wing damage, schedule restoration task activities need to be carried out.

IntvalPy — a Python Interval Computation Library

The article presents the IntvalPy library which implements interval computations in Python. Unlike other existing interval libraries, IntvalPy allows one to work with both classical interval arithmetic and complete Kaucher interval arithmetic. In addition, the library was developed taking into account the IEEE 1788-2015 standard for interval arithmetic on digital computers, which guarantees high accuracy of the results and compatibility with the other existing software products. The top-level functionality of the IntvalPy library implements state-of-the-art methods for recognizing and estimating solution sets for interval linear systems of equations, computing their formal solutions, and visualizing solution sets for interval equations and systems of equations. As an example of the library application, we solve the practically important problem of estimating the parameters of the electrochemical process of the formation of loose metal powder precipitates. Additionally, numerical computation was carried out, as well as qualitative comparisons with other interval libraries, in order to demonstrate the functionality and optimality of implemented interval classes.

Effect of Surface Dispersion of Fe Nanoparticles on the Room-Temperature Flash Sintering Behavior of 3YSZ

Arc floating in surface flashover can be controlled by reducing the interfacial charge-transfer resistance of ceramics. However, thus far, only a few studies have been conducted on methods of treating ceramic surfaces directly to reduce the interfacial charge-transfer resistance. Herein, we explore the flash sintering behavior of a ceramic surface (3 mol% yttria-stabilized zirconia (3YSZ)) onto which loose metal (iron) powder was spread prior to flash sintering at room temperature (25 °C). The iron powder acts as a conductive phase that accelerates the start of flash sintering while also doping the ceramic phase during the sintering process. Notably, the iron powder substantially reduces the transition time from the arc stage to the flash stage from 13.50 to 8.22 s. The surface temperature (~1600 °C) of the ceramic substrate is sufficiently high to melt the iron powder. The molten metal then reacts with the ceramic surface, causing iron ions to substitute Zr4+ ions and promoting rapid densification. The YSZ grains in the metal-infiltrated area grow exceptionally fast. The results demonstrate that spreading metal powder onto a ceramic surface prior to flash sintering can enable the metal to enter the ceramic pores, which will be of significance in developing and enhancing ceramic-metal powder processing techniques.

Production of nickel-rich LiNi0.89Co0.08Al0.03O2 cathode material for high capacity NCA/graphite secondary battery fabrication

Abstract Li-ion secondary battery is highly recommended as a power source to highly advanced battery electric vehicles. Among various types, the lithium nickel cobalt aluminum oxide (NCA) battery is considered suitable for high energy and power application. In this study, the NCA cathode material LiNi0.89Co0.08Al0.03O2 was produced via the oxalate co-precipitation technique to reduce the overall production cost and process complexity. Oxalic acid and a small amount of sodium hydroxide were used as the precipitant and pH regulator, respectively. Homogenous and loose metal oxalate precipitate formation was confirmed by X-ray diffraction (XRD), scanning electron microscopy, and Fourier-transform infrared spectroscopy analysis. XRD patterns of the as-obtained micron-sized NCA showed a well-layered hexagonal structure. The electrochemical properties of the cathode in the full cell were thoroughly examined. The specific discharge capacity of the as-obtained NCA in NCA/LiPF6/graphite at a current rate of 20 mA/g was 142 mAh/g. The as-prepared NCA sample had capacity retention of 80% after being charged and discharged at 0.1 A/g for 101 cycles. Scaling up of NCA production process to 2 kg per batch was conducted and evaluation of NCA product quality was performed by material characterization. Based on the overall results and considering the overall process, such an approach is expected to be developed and improved for future large-scale production purposes.

Metal additive manufacturing via a novel composite material using powder and polymers formed in sheets

In additive manufacturing, PowderBed Fusion (PBF) has been shown to be a highly reliable approach for prototyping of metal parts, but has several disadvantages: relative slow production time, inherent safety issues involved with using loose metal powders, and difficulty in printing multi-material parts. A novel method for additive manufacturing of metal parts, Metal Additive manufacturing using Powder Sheets (MAPS), is hereby described. MAPS uses rollers of a novel composite material as feedstock, which eliminates the need for loose powder in the build chamber, potentially reducing risks and enhancing applications while still producing material on par with that produced by established PBF methods.

Design and Analysis of Chips Block Making Machine

Machinery in industries is used to change the size and shape of the raw material to obtain the required work piece. During this process, metal chips of different types and size are obtained. These metal chips are collected manually and are transported to local scrap yards, where recycling processes takes place. During transportation, most of these metal chips are lost or not recycled due to its size. Chips Block Making Machine can convert the collection of loose metal chips to a whole block. These blocks can be transported to scrap yards more efficiently. This process is carried out by using the principle of Thermal compression. Flow simulation in Solid Works is used as a tool to analyse the exposed environmental temperature from inner body of the machine. As a result, the efficiency of transporting these metal chips is increased and recycling process can be done more comfortably.

Determination of the Growth Time Period of Loose Zinc Deposit Using Interval Analysis Methods

A characteristic of obtaining metal powders by direct current electrolysis is changes in the morphology of particles over the loose deposit layer thickness up to the formation of large spherulites. Deposits should be periodically removed from the cathode in order to obtain a powder with homogeneous composition. This paper justifies the choice of the parameter describing the change in loose deposit properties and proposes a method for determining the periodicity of its removal from the cathode. Loose zinc deposits were obtained at 25°C from zincate electrolyte containing 0.3 mol L–1 of ZnO and 4 mol L–1 of NaOH at a current setpoint exceeding six times the limiting diffusion current calculated using the smooth electrode. Electrode potential, deposit thickness and evolved hydrogen volume were measured directly in the process of electrolysis. Current redistribution between the metal reduction and hydrogen evolution leads to a change in the structure of loose deposit particles. It is shown that the differential current efficiency of zinc is the parameter describing the change in the loose zinc deposit density. Its value should not exceed 0.96, in order to ensure deposition of loose deposit with homogeneous properties. A further increase in current efficiency will lead to the formation of aggregates at the deposit growth front. It is proposed to determine the periodicity of loose deposit removal from the cathode using the empirical equation for the time dependency of differential current efficiency of zinc. The mathematical and statistical analysis of the data obtained in six replicates was carried out. The interval approach made it possible to significantly narrow the range of permissible differential current efficiency values and, as a consequence, to determine empirical equation coefficients with acceptable accuracy and calculate the growth time period of a deposit with homogeneous structure. The obtained approach can be used to estimate the time period of loose metal deposition accompanied by hydrogen evolution.

Features of hydrogen evolution during electrodeposition of loose deposits of copper, nickel and zinc

Abstract Features of hydrogen evolution during electrodeposition of dendritic copper, zinc and nickel deposits were studied in the present paper. Data on the changes in hydrogen current density and its differential current efficiency as well as porosity of copper, zinc and nickel deposits during electrolysis were obtained. It was shown that the potential during the formation of dendritic metal deposits is determined by the kinetic parameters of hydrogen reduction. Experimental data (the change in the electrode potential during electrodeposition and volume of evolved hydrogen) and hydrogen evolution kinetic parameters allowed to calculate the surface area available for hydrogen evolution during electrodeposition of loose metals. It was found that surface area available for hydrogen evolution increases during electrodeposition of loose metal under galvanostatic conditions. Morphology of dendrite particles and deposit growth rate are determined by metal nature, but properties of loose deposits (change in porosity along the deposit thickness) depend on the intensity of hydrogen evolution during electrolysis.

Determination of the growth time period of loose zinc deposit using interval analysis methods

The peculiarity of obtaining metal powders by direct current electrolysis is changes in the morphology of particles over the loose deposit layer thickness up to the formation of large spherulites. Deposit should be periodically removed from the cathode in order to obtain a powder with homogeneous composition. This paper justifies the choice of the parameter describing the change in loose deposit properties, and proposes a method for determining the periodicity of its removal from the cathode. Loose zinc deposits were obtained at 25 °C from zincate electrolyte containing 0.3 mol·l –1 of ZnO and 4 mol·l –1 of NaOH at a current setpoint exceeding 6 times the limiting diffusion current calculated using the smooth electrode. Electrode potential, deposit thickness and evolved hydrogen volume were measured directly in the process of electrolysis. Current redistribution between the metal reduction and hydrogen evolution leads to a change in the structure of loose deposit particles. It is shown that the differential current efficiency of zinc is the parameter describing the change in the loose zinc deposit density. Its value should not exceed 0.96 to ensure deposition of loose deposit with homogeneous properties. A further increase in current efficiency will lead to the formation of aggregates at the deposit growth front. It is proposed to determine the periodicity of loose deposit removal from the cathode using the empirical equation for the time dependency of differential current efficiency of zinc. The mathematical and statistical analysis of the data obtained in six replicates was carried out. The interval approach made it possible to significantly narrow the range of permissible differential current efficiency values and, as a consequence, to determine empirical equation coefficients with acceptable accuracy and calculate the growth time period of a deposit with homogeneous structure. The obtained approach can be used to estimate the time period of loose metal deposition accompanied by hydrogen evolution.

AgNWs-graphene transparent conductor for heat and sensing applications

Despite various research efforts, the realization of ideal flexible, transparent and highly stable conductors have not been made possible so far in future technologies. Here we report the fabrication of spin-coated metal-graphene network with high-performance properties, reduced sheet resistance (≈20.58 Ω/□), optimum transmittance (≈86%), lower surface roughness ≈14.8 nm), and excellent long-term reliability with heating up to ≈280 °C. In addition, the transparent electrode exhibits remarkable sensing response towards molecular ammonia gas. These features arise from a bridging of the metal nanowire network with graphene nanoplatelets, which provides, a protective sheet for metal nanowires, additional conducting channels that bridges the closely located loose metal nanowires increasing the thermal stability and mobility of carriers in graphene. The sensing response arises from the presence of AgNWs bridges that causes a decrement in high energy binding sites and increment in low binding energies sites in graphene. Further development of this strategy will thus pave a way toward next-generation hybrid TCFs devices serving dual performance for wearable thermotherapy flexible electronics and chemical sensor devices.

Reducing surface roughness by chemical polishing of additively manufactured 3D printed 316 stainless steel components

As-produced laser-sintered metal additively manufactured components possess a high roughness and unsuitable surface texture that may lead to several forms of crack generation under static and dynamic loading. This problem is even more severe for additively manufactured (AM) components with intricate geometries involving a large internal surface area. Here, we report the application of the chemical polishing method to improve the surface finish of 316 steel components. After chemical polishing, the AM component surface became dull gray to bright lustrous and surface morphology improved remarkably. As a distinctive advantage, chemical polishing effectively reduces the roughness of the internal and external surfaces of the AM component. The Ra roughness parameter changed from ~ 5 to ~ 0.4 um for the outer surface. However, for the inner surface of the AM component, where abrasive blasting or shot pinning was unable to remove loose metal powder, the Ra surface roughness reduced from ~ 15 to ~ 0.4 um. Our SEM study showed that chemical polishing produced the surface texture covered with ~ 0.3-μm-wide sub-microscopic convex hull-shaped regions. During chemical polishing, material removal preferably occurred from the interior regions of the ubiquitous sub-microscopic regions. The roughness measurement conducted with SEM on a ~ 20-μm scan length chemical polished sample was Ra 0.37 μm. Roughness study in SEM was in close agreement with the roughness measurement performed with optical profilometer over several millimeter-long scan lengths resulting in a ~ 0.4-μm Ra. These studies suggested that chemical polishing produced uniform surface reduction over a large area.

Effect of Parameters of Pulsed Potential Mode on Concentration Changes in the Bulk Loose Zinc Deposit and Its Properties

It is shown that the parameters of pulsed potential modes (pulse-on and pulse-off times) have a pronounced effect on the growth dynamics and properties of loose metal deposits in the cases that the process proceeds under the conditions of non-steady-state diffusion. It is proposed to use a ratio between the cathodic and anodic charges in a cycle as a parameter that characterizes the concentration changes. By varying the parameters of pulsed potential, zinc deposits of various morphology can be obtained: from compact deposits to highly porous deposits that consist of branched dendritic particles.

Laser induced breakdown spectroscopy for multielement analysis of powdered materials used in additive technologies

ABSTRACTAdditive manufacturing technologies utilizing metal parts production with layer by layer printing are of high demand for different fields of science and technology. Analytical chemistry is challenged to provide multielemental quantitative analysis of any metal powders within a few minutes and onsite to fulfil the requirements for high quality metal parts production. Powder materials utilized in additive technologies were quantitatively analyzed by laser induced breakdown spectroscopy for the first time. Laser induced breakdown spectroscopy mapping of loose metal powder attached to the double-sided adhesive tape provided high reproducibility of measurements even for powder mixtures with large difference of particles densities (tungsten carbide particles in nickel alloy powder). Laser induced breakdown spectroscopy analytical capabilities were estimated for tungsten and carbon analysis by calibration curve construction and accuracy estimation by leave-one-out cross-validation procedure. Laser induced breakdown spectroscopy and X-ray fluorescence spectroscopy techniques comparison revealed better results for laser induced breakdown spectroscopy analysis. Improved accuracy of analysis and capability to quantify light elements (carbon, etc.) demonstrated the potential of laser induced breakdown spectroscopy as a promising technique for express onsite multielement analysis of powder materials utilized in additive technologies.

Determination of the surface area of loose metal deposits by impedance spectroscopy

The surface area and fractal dimensions of the surface of loose copper and zinc deposits obtained within 30 and 300 s at direct current sixfold exceeding limiting diffusion current on a smooth electrode were in situ determined by impedance spectroscopy. Impedance measurements were performed in 0.5 M Na2SO4 solution. A constant phase element taking into account the distribution of double-layer capacitance over the fractal surface of the electrode was used in the equivalent impedance scheme. Specific surface calculated with regard to the weight of the released metal slightly varied within 300 s (from 6.16 to 6.55 and from 7.12 to 5.89 m2/g for copper and zinc deposits, respectively). Fractal dimensions estimated by chronopotentiometry were given for comparison. Fractal dimensions found by two methods for loose copper and zinc deposits agree with each other; their values (2.19–2.75) testify that the surface of the deposits densely fills the space.

Measurement and augmentation of effective thermal conductivity of La0.8Ce0.2Ni5 hydride bed

Abstract An experimental set up for measuring Effective Thermal Conductivity (ETC) of Metal Hydride (MH) beds was fabricated using one-dimensional steady-state radial heat transfer absolute method. La 0.8 Ce 0.2 Ni 5 alloy powder and its hydride were considered in the present study. Two types of compacts were fabricated for ETC augmentation of MH bed. First type was made from the mixture of 6 wt% graphite flakes with the La 0.8 Ce 0.2 Ni 5 alloy powder. A three dimensional structure, having six radial fins, uniformly distributed around the outer periphery of a hollow cylinder, made with copper wire mesh, was integrated with the mixture of La 0.8 Ce 0.2 Ni 5 powder and 6 wt% graphite flakes to make the second type of compacts. The ETC of the three types of beds namely loose metal powder bed (LMP), bed of compacts of metal alloy powder mixed with graphite flakes (CMPGF) and bed of compacts of metal alloy powder mixed with graphite flakes and embedded with copper wire mesh structure (CMPGFCu) were measured and compared at different argon and hydrogen pressures, hydrogen concentrations and average bed temperatures. The maximum values of effective thermal conductivity for the bed configurations of LMP/CMPGF/CMPGFCu were 1.3/4.7/6.8 W m −1 K −1 . These values of effective thermal conductivity were obtained at 70 bar hydrogen gas pressure and 60 °C average bed temperature. The decrease in mass fraction of hydrogen absorbed by the La 0.8 Ce 0.2 Ni 5 hydride, as a result of implementation of ETC augmentation techniques, was nominal (around 5.7% in case of CMPGF and 4.5% in case of CMPGFCu) when compared to the respective powder bed configurations.