Behaviour Of Different Metals Research Articles

Magmatic evolution and metal systematics of back-arc volcanic rocks of north–east Japan and implications for deposition of massive sulphide Kuroko ores

The Hokuroku region of north-eastern Japan is endowed with important volcanic-hosted massive sulphide Zn–Pb–Cu deposits, which are considered the archetype of Kuroko (black ore) deposits worldwide. The bimodal, felsic-dominated volcanic succession that hosts the ore was deposited in a continental rift formed during continental extension in the final stages of the Miocene back-arc opening that led to the formation of the Japan Sea. In this study, we define some of the fundamental intensive parameters of this volcanism (temperature, pressure of crystallisation, fluid saturation, fO2) based on rock textures, and analyses of whole-rock samples, minerals and melt inclusions. Based on the melt inclusion analyses, we assess the behaviour of metals during magma evolution and degassing, and evaluate the possible implications for ore deposition. Plagioclase-melt geothermometry in felsic tuff and lava samples collected from both the units underlying and overlying the Kuroko indicates temperatures of 880–940 °C, and Fe–Ti oxide equilibrium indicates oxygen fugacity of ca. FMQ + 1.5. Melt inclusions have high-SiO2 rhyolite compositions (> 75 wt%, on an anhydrous basis), and the plot of normative mineral compositions in the granitic triplot indicates low pressure of magma stalling and crystallisation (< 1 kbar) at cotectic compositions. Melt inclusion metal contents plotted vs incompatible element Y suggest contrasting behaviour of different metals during fractionation and degassing. Zinc was mostly retained in the melt during crystallisation, whereas other metals, such as Pb, Cu, Sn and Mo, were released to an exsolving fluid phase. The latter may have thus been transferred to the hydrothermal system from a degassing magma. Shallow storage of relatively hot magma would have induced vigorous hydrothermal circulation on the seafloor, a precondition for ore deposition.

High-Entropy Alloy Aerogels: A New Platform for Carbon Dioxide Reduction.

High-entropy alloy aerogels (HEAAs) combined with the advantages of high-entropy alloys and aerogels are prospective new platforms in catalytic reactions. However, due to the differences in reduction potentials and miscibility behavior of different metals, the realization of HEAAs with a single phase is still a great challenge. Herein, a series of HEAAs is fabricated via the freeze-thaw method as highly active and durable electrocatalysts for the carbon dioxide reduction reaction (CO2 RR). Especially, the PdCuAuAgBiIn HEAAs can achieve Faradaic efficiency (FE) of C1 products almost 100% from -0.7 to -1.1V versus reversible hydrogen electrode (VRHE ), and a maximum FE for formic acid (FEHCOOH ) of 98.1% at -1.1VRHE , outperforming PdCuAuAgBiIn high-entropy alloy particles (HEAPs) and Pd metallic aerogels (MAs). Specifically, the current density and FEHCOOH are almost 200mAcm-2 and 87% in a flow cell. The impressive CO2 RR performance of the PdCuAuAgBiIn HEAAs is attributed to the strong interactions between the different metals and the surface unsaturated sites, which can regulate the electronic structures of different metals and allow the optimal HCOO* intermediate adsorption and desorption onto the catalysts surface to enhance HCOOH production. The work not only provides a facile synthetic strategy to fabricate HEAAs, but also opens the avenue for development of efficient catalysts and beyond.

Cyclic Extrusion Compression Process for Achieving Ultrafine-Grained 5052 Aluminum Alloy with Eminent Strength and Wear Resistance

Previous studies have yet to show a consistent effect of severe plastic deformation (SPD) processing on the wear behavior of different metals and alloys. To fill this scientific gap, this study investigated the effect of the cyclic extrusion compression (CEC) process, as one of the prominent SPD techniques, on the wear behavior of AA5052. In addition, the microstructure evolution and mechanical properties of the sample before and after the process were experimentally examined and studied. It was found that the yield and ultimate tensile strength of the AA5052 improved significantly after the first pass, while the elongation-to-failure decreased considerably. Further, the subsequent passes mildly changed the trend of increasing strength and reducing elongation-to-failure. SEM morphology indicated that the ductile mode of the initial annealed alloy changed to a combination of ductile and brittle failure modes, in which the level of the brittle failure mode increased with the addition of passes. TEM observations showed that the grain refinement during the CEC process included the formation of dislocation cell structures, subgrain boundaries, and low-angle grain boundaries, with the subgrain boundaries initially evolving into low-angle grain boundaries and, eventually, due to the imposition of additional plastic strain, into high-angle grain boundaries. Furthermore, the CEC process and its increased number of passes led to a significant improvement in wear resistance due to the enhanced tensile strength achieved through grain refinement. In this regard, the wear mechanism of the initial alloy was a combination of adhesion and delamination, with the plastic deformation bands changing to plowing bands with decreased adhesive wear during the process. Eventually, oxidization was found to be a mechanism contributing to wear under all conditions.

Short-Range Diffusion Enables General Synthesis of Medium-Entropy Alloy Aerogels.

Medium-entropy alloy aerogels (MEAAs) with the advantages of both multimetallic alloys and aerogels are promising new materials in catalytic applications. However, limited by the immiscible behavior of different metals, achieving single-phase MEAAs is still a grand challenge. Herein, a general strategy for preparing ultralight 3D porous MEAAs with the lowest density of 39.3 mg cm-3 among the metal materials is reported, through combining auto-combustion and subsequent low-temperature reduction procedures. The homogenous mixing of precursors at the ionic level makes the short-range diffusion of metal atoms possible to drive the formation of single-phase MEAAs. As a proof of concept in catalysis, as-synthesized Ni50 Co15 Fe30 Cu5 MEAAs exhibit a high mass activity of 1.62 A mg-1 and specific activity of 132.24 mA cm-2 toward methanol oxidation reactions, much higher than those of the low-entropy counterparts. In situ Fourier transform infrared and NMR spectroscopies reveal that MEAAs can enable highly selective conversion of methanol to formate. Most importantly, a methanol-oxidation-assisted MEAAs-based water electrolyzer can achieve a low cell voltage of 1.476 V at 10 mA cm-2 for making value-added formate at the anode and H2 at the cathode, 173 mV lower than that of traditional alkaline water electrolyzers.

INVESTIGATION ON THE THERMAL BEHAVIOR OF FRICTION STUD WELDING OF DISSIMILAR ALUMINUM/MILD STEEL JOINTS

Friction stud welding process is a suitable candidate in joining stud fasteners for steel structure buildings, military vehicles, automobiles, aircraft, ocean liners, bridges, ship buildings, etc., The peak temperature for welding is achieved by converting mechanical energy to thermal energy at the sample interface without the use of electric energy from other sources because it is a solid-state process. The study of the thermal behavior of different metals during friction stud welding is very important since it is a thermal energy process. However, there is no good thermal model for the friction stud welding process. In this work, the generation of heat flux at the interfacial area of two distinct metals, namely aluminum and mild steel, is calculated using a mathematical model. The temperature at the interfacial region, which plays a significant role in the quality and strength of the weld component, is particularly focused on experimentation and analytical modeling. In the experimentation, a noncontact type infrared thermometer is used to measure temperature directly. The temperature profile was determined by the finite difference method based on thermal resistance and capacitance formulation at transient conditions. The obtained mathematical results are compared with the experimental results at the distance of 5 and 10[Formula: see text]mm from the welded interface. The computed temperature profile is in good agreement with the experimental data on the heating side and with a minimum degree of deviation in the cooling part. The maximum percentage of error for the 5[Formula: see text]mm interface is 3.349 and for the 10[Formula: see text]mm interface is 2.857. This deviation is due to the zero-axial shortening assumption in the analytical model. Besides, the temperature characteristics of the welded are analyzed at various time increments by numerical simulation. As a result, the predicted temperature is more on the aluminum side compared to the mild steel due to a change in thermal properties. This proposed thermal model would be helpful to improve the design and manufacture of welding machines.

2D and 3D cellular automata simulation on the corrosion behaviour of Ni-based alloy in ternary molten salt of NaCl–KCl–ZnCl2

When molten salt is used as a high-temperature heat carrier or electrolyte solution, the corrosion of molten salt is necessary to be studied regarding the device's safety. In this work, a cellular automata method is used to simulate the corrosion behaviour of alloys in ternary molten salt of NaCl–KCl–ZnCl 2 . The CA method described in this paper can be used to reproduce the distribution of corrosion products and components and the change in morphology and thickness of the corrosion layer in the phase of high-temperature corrosion, which provides a unique insight into the corrosion behaviour of chloride molten salt over time. In addition, we also consider the pitting corrosion that may occur during the corrosion process. Furthermore, the applicability of the model can predict the corrosion behaviour of different metals in molten chloride salt. • Cellular automaton (CA) method is proposed to study molten chloride salt corrosion. • The simulation of cross-sectional corrosion morphology of alloy is proposed. • The growth process of a single corrosion pit is simulated innovatively. • A novel 3D CA model realizes the calculation of the corroded volume.

TLM Analysis of Metal Contacts for 2D MoS2 Nanoflakes Deposited by Chemical Vapour Deposition-free technique

In the past decade, two-dimensional (2D) nanomaterials are gaining significant attention due to their novel properties in electrical, optical, mechanical which are different from their bulk forms. Therefore, it becomes one of the most promising materials for sensing applications. However, to connect the 3D world with 2D materials require excellent communication links which is a contact that renders remarkable electrical properties and specifically 2D nanomaterials-based sensor has been suffering from high resistance and low sensitivity due to the loss caused by poor contact between the 2D nanomaterials and metal interface. This work explores the electrical properties of metal/2D contacts by the rectangular transmission line method (TLM). The critical resistance parameters such as sheet and specific contact resistance were determined by characterizing the current-voltage (IV) relation. The behavior of different metals (silver and gold) contacts to 2D MoS2 nanoflakes deposited on Si substrate by low-cost spray coating technique are observed. These metals are chosen based on the work function relative to the electron’s affinity, χ of MoS2. UV-Vis’s analysis is carried out to estimate the final concentration of MoS2 solution.

Scanning Electrochemical Probe Microscopy for Corrosion-Fatigue Manipulation

Corrosion-fatigue is used to describe the weakening of the material resulting from the cyclic loading in a corrosive environment. Understanding this phenomenon reflects on a wide range of electrochemical applications such as hydraulic turbines and gives a better influence on the microstructure defect which by far isn’t clear yet. The ability to investigate the corrosion-fatigue at its point of initiation with a high spatial resolution is believed to manipulate and limit its occurrence on metal surfaces. However, conventional methodologies used are limited to average-base electrochemical studies leaving it insufficient for single-point measurements. Scanning electrochemical probe microscopy, for instance, allows us to map and characterize the corrosion behavior of different metals including its cracking initiation and propagation, at the micro-scale while maintaining a high resolution. Interesting about this technique is its ability to accommodate with non-linear heterogeneous surfaces due to the sewing-needle like microelectrode that moves up and down alternatively without ruining the non-flat superficial. As such, our aim in this project is to exploit the advantages of the SEPM techniques in order to study and monitor the synergistic effect between the fatigue and the corrosion behavior on the surface of some metals.

Electro-chemical behaviour of different metals in Sodium Chloride solution

Electro-chemical behaviour of different metals in Sodium Chloride solution

Investigations in the field of material mechanics using strain gages

AbstractIn this contribution, investigations of the stress‐strain behavior of different metals using strain gage technique are presented. The measurement of strains using strain gages provides high measuring accuracy. In case of large deformations, the nonlinearity of the resistance‐strain‐relation, including elastic and plastic strain of the gage grid material, has to be considered. Moreover, for the detection of large deformations, high‐elongation strain gages and special bonding adhesives are used. Furthermore, at larger resistance changes the nonlinearity of the Wheatstone bridge has to be taken into account. As an example, the stress‐strain behavior of the steel 50CrV4 with 3 different process states in the small deformation range during tensile tests is demonstrated. The differences of the resulting stress‐strain curves of the material in the different process states are analyzed. Additionally, specimens of the aluminum alloy EN AW‐2024 are investigated in a large deformation range using tensile tests. Therein, the strain transmission enabled by the bonding is in the special focus. Furthermore, results of the large deformation tests are compared to the strain measurement using Digital Image Correlation.

Modeling FBG sensors sensitivity from cryogenic temperatures to room temperature as a function of metal coating thickness

Abstract Fiber optics with photo-imprinted Bragg grating have been studied in order to be used as temperature sensors in cryogenic applications. The main disadvantage presented by Fiber Bragg Grating (FBG) sensors is the significant drop in sensitivity as temperature decreases, mainly due to the critical lowering of the thermo-optic coefficient of the fiber and the very low thermal expansion coefficient (CTE) of fused silica at cryogenic temperatures. Thus, especially for the latter, it is important to enhance sensitivity to temperature by depositing a metal coating presenting higher CTE. In this work the thermal sensitivity of metal-coated FBG sensors has been evaluated by considering their elongation within temperature variations in the cryogenic range, as compared to bare fiber sensors. To this purpose, a theoretical model simulating elongation of metal-coated sensors has been developed. The model has been used to evaluate the behaviour of different metals which can be used as coating ( Ni , Cu , Al , Zn , Pb and In). The optimal coating thickness has been calculated at different fixed temperature (from 5 K to 100 K) for each metal. It has been found that the metal coating effectiveness depends on thickness and operating temperature in accordance to our previous experimental work and theory suggest.

Inhibition study of additives towards the corrosion of ferrous metal in palm biodiesel

Some efforts have already been given by other researchers to characterize the corrosion behavior of different metals in biodiesel. However, there is very limited information on its remedial measure. Therefore, this study investigates the effects of tert-butylamine (TBA), benzotriazole (BTA), butylate-dhydroxytoluene (BHT), and pyrogallol (PY) on the corrosion of cast iron (CI) and low carbon steel (LCS) through an immersion test in palm biodiesel (B100) at 300K. Result shows that TBA-doped biodiesel exhibits fairly good corrosion-inhibiting properties for materials exposed to B100. Inhibition efficiency of TBA is found to be 86.54% and 86.71% for CI and LCS, respectively which is far better than other tested additives in this study. The high inhibition efficiency could be attributed to the dominant physical adsorption of N-containing compound which creates a protective layer over the metal surface and prevents corrosion.

Measurements of Gas Shielding Factors for Cu, Fe, Ni

Knowledge of the vaporization behavior of different metals in dependence of temperature, pressure of the ambient atmosphere as well as its purity, is a crucial issue for high temperature materials. It has even been proven in the literature that the amount of mass loss of a sample due to vaporization strongly depends on the purity of the atmosphere in which the sample is heated. This coincides with the value of partial pressures of specific impurities. The so called gas shielding factor describes the ratio of the evaporation rate in a specific gas atmosphere and the evaporation rate under UHV. The dependence of the gas shielding factor on the pressure and the purity of the process gas is remarkable. The range can extend over several orders of magnitude [1]. Within the framework of the presented work, vaporization experiments using a HT- Thermobalance with UHV supply have been carried out for the elements Fe, Cu, and Ni under inert gas atmosphere and with defined oxygen partial pressures. Thereby, the oxygen partial pressure has been maintained using an oxygen ion pump. Here, an electric current between +10 and -10 mA is applied to an yttrium-doped zirconia tube operated at a temperature of 600 °C. The current flow results in oxygen being transferred into or out of the ambient gas provided to the experimental set-up with a flow rate of about 2 cm3/min. The ion pump yields accuracy in oxygen flow of 10-9 l/min and, therefore, enabled precise adjustment of pO2 within the area of interest. The gas shielding factor not only depends on the gas purity but also on the investigated material itself. The dependency from the oxygen partial pressure for example is influenced by the partial vapor pressure of the corresponding oxides and their dissociation pressure. Reference [1] E. Fromm, METALLURGICAL TRANSACTIONS A, VOLUME 9A , DECEMBER 1978, 1835-1838

Correction: Understanding the behaviour of different metals in loaded scintillators: discrepancy between gadolinium and bismuth

Correction for ‘Understanding the behaviour of different metals in loaded scintillators: discrepancy between gadolinium and bismuth’ by Guillaume H. V. Bertrand et al., J. Mater. Chem. C, 2015, 3, 6006.

Understanding the behaviour of different metals in loaded scintillators: discrepancy between gadolinium and bismuth

A case study: the quenching effect of organometallics containing bismuth or gadolinium was studied in fluorescent polymers.

A Study on Cavitation Erosion Behavior of Different Metals in Biomass Fuel/Diesel Blend

The cavitation erosion behavior of different metals, such as pure copper (Cu), steel GCr15 (ASTM A295) and stainless steel 1Cr18Ni9Ti (ASTM A276 321), in the emulsified biomass fuel/diesel (10wt% biomass fuel in blend with diesel fuel) was investigated by using a magnetostrictive-induced cavitation vibratory apparatus. The morphology of surface was observed by optical microscope and scanning electron microscope, and the cavitation erosion rates of three metals were evaluated by mass loss method. The surface compositions after cavitation erosion were analyzed by energy-dispersive X-ray spectroscopy. The experimental results showed that the surface morphologies and elements of Cu and GCr15 were changed greatly before and after cavitation erosion in the emulsified biomass fuel/diesel blend, as contrast to 1Cr18Ni9Ti. The degree order of cavitation erosion among three metals was Cu, GCr15 and 1Cr18Ni9Ti, because that the anti-corrosion effect of 1Cr18Ni9Ti played a great role in the mass loss by cavitation erosion.

An Overview on the Fracture Behavior of Metals Processed by High Pressure Torsion

Motivated by the large variety of enhanced properties of ultrafine and nanocrystalline materials such materials are under extensive investigation. Besides focusing on classical material parameters, like strength and ductility, the fracture toughness of these materials is also of great importance, especially when the damage tolerance is required. In this contribution an overview of the fracture behavior of different metals covering ultrafine-grained iron and nickel as well as a nanocrystalline steel processed via high pressure torsion (HPT) will be given. It will be shown that the specimen orientation can have a tremendous influence on the fracture behavior and toughness. Due to this toughness anisotropy an unexpectedly good combination of high strength and high fracture toughness can be achieved very often in these materials.

Patterns of metal bioaccumulation in two filter-feeding macroinvertebrates: Exposure distribution, inter-species differences and variability across developmental stages

This study focused on the metal bioaccumulation of two aquatic insects ( Ephoron virgo and Hydropsyche spp.) in order to evaluate the spatial distribution of metals, the interspecific differences between both filter-feeders and the bioaccumulation dynamics during E. virgo development stages. Hg, Cd, Ni, Cr, As, Pb, Cu, Ti, Zn and Mn were quantified in insects and in suspended particulate matter (SPM) sampled downstream and upstream of a chemical plant, where more than 300,000 t of polluted sediments are deposited. Hg concentrations were one order of magnitude higher downstream of the sediment dump, which showed that the Hg pollution originated in the chemical plant. Cd, Ni, Cr, Pb, Ti, Zn and Mn in invertebrates revealed that metal pollution was present upstream in other parts of the river. Interspecific differences were observed for all metals but Mn; significantly higher concentrations were observed in E. virgo over Hydropsyche exocellata, except for Cd, which showed 10-fold higher values. Hg and Cd increased until E. virgo nymphs reached 11 mm and decreased afterwards in late instars when nymphs were about to emerge. Cr, Pb, Ti and Mn decreased along early instars followed by a steady state in late instars. Similar values were obtained for Cu, As and Zn along all instars. Sexual differences between males and females of E. virgo were observed for Cd, Cu and Mn. Hg and Cd persistence was strong across developmental stages since high concentrations were found in eggs and emerging adults. Because the behavior of different metals varied for the two species and during the developmental stages of E. virgo, care should be taken in the interpretation of insect metal concentrations when analyzing the food chain transfer of metals in river ecosystems.

Forms of heavy metal compounds in soils of the steppe zone

A parallel scheme of extractions was used for determining heavy metal compounds in uncontaminated and artificially contaminated soils of Rostov oblast. A method for calculating the contents of complex and specifically adsorbed metal compounds from the difference in their concentrations in different extracts was suggested. It was found that the portion of firmly fixed metal compounds decreases and the portion of potentially mobile (exchangeable, complex, and specifically adsorbed) metal compounds increases with an increase in the degree of contamination of chernozems and chestnut soils with lead, copper, and zinc over a one-to two-year-long observation period. This was due to the capacity of heavy metal ions to substitute for the exchangeable cations in the exchange complex of the studied soils, to form complexes with the soil organic matter, and to participate in the specific adsorption. Some differences in the behavior of different metals were found.

Influence of material properties on extraordinary optical transmission through hole arrays

We present a theoretical study, based on the finite difference time domain method, of the optical response of circular hole arrays drilled in several metal films (Ag, Au, Cu, Al, Ni, Cr, and W). Two series of structures are studied. In the first one, transmittance peaks are analyzed as all geometrical parameters defining the system are scaled, except for the metal thickness which is kept constant, showing good agreement with existing experimental data. In the second series, the metal thickness is also scaled. This allows a clear distinction in the behavior of different metals: Ag, Au, and Cu show even larger transmittance peaks than hole arrays in a perfect conductor with the same nominal parameters. This is due to both a larger effective hole area and smaller absorption. In the case of Ni and Cr, the transmittance is much smaller due to absorption. Band structure calculations confirm that surface electromagnetic modes sustained by the perforated metal film are responsible for the extraordinary optical transmission phenomenon.