Metal Loss Research Articles

Efficient light extraction from an apex quantum dot coupled to a single-mode optical fiber

Deterministic quantum dots (apex-QDs), which are spontaneously formed at the vertex of pyramid structures, are an attractive single-photon source. Herein, we propose the design of apex-QDs coupled to a single-mode optical fiber for directional emission from a quantum dot, followed by optimization of the structural parameters to maximize the extraction efficiency toward the fiber using FDTD simulation. A dielectric layer of SiO2 was inserted between a silver and a quantum dot to minimize the metallic loss and control the distance between them. For this, the optimum layer thicknesses of silver and SiO2 were 100 nm and 240 nm, respectively, achieving 94% light collection downward near 600 nm in wavelength. The proposed structure was then coupled to a tapered optical fiber, achieving 60% of the quantum dot emission. This high collection through an optical fiber was observed for a wide range of emission wavelengths.

Cathode-Electrolyte Interphase in Lithium Batteries Revealed by Cryogenic Electron Microscopy

Summary Cathode electrolyte interphase (CEI), the intimate coating layer formed on the positive electrode, has been thought to be critical. However, many aspects of CEI remain unclear. This originates from the lack of effective tools to characterize structural and chemical properties of these sensitive interphases at nanoscale. Here, we develop a protocol to preserve the native state and directly visualize the interface on the positive electrode using cryogenic electron microscopy. We find that under normal operation conditions, there does not exist an intimate coating layer at the single-particle level in carbonate-based electrolyte. However, upon brief external electrical shorting, a solid-electrolyte interphase, which usually forms on anodes, could form on cathodes and be electrochemically converted into a stable, conformal CEI in situ. The conformal CEI helps improve Coulombic efficiency and overall capacity retention of the battery. This generates a different perspective of CEI in commercial carbonate-based electrolytes than previously understood.

Effect of Laser Heat-Treatment and Laser Nitriding on the Microstructural Evolutions and Wear Behaviors of AISI P21 Mold Steel

Laser heat-treatment and laser nitriding were conducted on an AISI P21 mold steel using a high-power diode laser with laser energy densities of 90 and 1125 J/mm2, respectively. No change in surface hardness was observed after laser heat-treatment. In contrast, a relatively larger surface hardness was measured after laser nitriding (i.e., 536 HV) compared with that of the base metal (i.e., 409 HV). The TEM and electron energy loss spectroscopy (EELS) analyses revealed that laser nitriding induced to develop AlN precipitates up to a depth of 15 μm from the surface, resulting in surface hardening. The laser-nitrided P21 exhibited a superior wear resistance compared with that of the base metal and laser heat-treated P21 in the pin-on-disk tribotests. After 100 m of a sliding distance of the pin-on-disk test, the total wear loss of the base metal was measured to be 0.74 mm3, and it decreased to 0.60 mm3 for the laser-nitrided P21. The base metal and laser heat-treated P21 showed similar wear behaviors. The larger wear resistance of the laser-nitrided P21 was attributed to the AlN precipitate-induced surface hardening.

Parity-time symmetric plasmonic planar superlens

A superlens which involves plasmonic mode could compensate for the loss of high spatial frequency information and achieve super-resolution. However, their working distance is limited to near field region due to the intrinsic loss of metal and the imaging properties are usually distorted by the experimental errors. We investigate a layered planar superlens structure with parity-time (PT) symmetric potential. By utilizing the transfer matrix method, we observe the eigenspectrum of plasmonic mode depends on PT potential. Numerical simulation results, obtained by using the Finite Element Method, show that the working distance of super-resolution can be increased in the PT symmetric superlens. In addition, the resolution could be improved by adjusting the PT symmetric potential, demonstrating the PT symmetry introduced a great advantage of robustness to experimental errors.

Characterization of E-cigarette coil temperature and toxic metal analysis by infrared temperature sensing and scanning electron microscopy – energy-dispersive X-ray

Introduction Electronic cigarettes (e-cigarettes) have rapidly evolved since their introduction to the U.S. market. The rebuildable atomizer (RBA) offers user-driven modification to the heating element (coil) and wicking systems. Different coil materials can be chosen based on user needs and preferences. However, the heating element of an e-cigarette is believed to be one-source for toxic metal exposure. Methods E-cigarette coils from Kanthal and nichrome wires were constructed in a contact and non-contact configuration and heated at four voltages. The maximum temperatures of the coils were measured by infrared temperature sensing when dry and when saturated with 100% vegetable glycerin or 100% propylene glycol. The metal composition of each coil was analyzed with Scanning Electron Microscopy-Energy-Dispersive X-Ray (SEM-EDX) when new, and subsequently after 1, 50, and 150 heat cycles when dry. Results The coils reached temperatures above 1000 °C when dry, but were below 300 °C in both liquid-saturated mediums. Metal analysis showed a decrease of 9–19% chromium and 39–58% iron in Kanthal wire and a decrease of 12–14% iron and 39–43% nickel in nichrome wire after 150 heat cycles. Significant metal loss was observed after one heat cycle for both coil alloys and configurations. Conclusions The loss of metals from these heat cycles further suggests that the metals from the coils are potentially entering the aerosol of the e-cigarette, which can be inhaled by the user.

Design and Loss Reduction of Multiple-Zeros Dual-Band Bandpass Filter Using SISL

This brief proposed a dual-band bandpass filter (DBBPF) topology realized on substrate integrated suspended line (SISL) platform. In this topology, separated electric and magnetic coupling paths (SEMCP) is firstly applied between two different filter bands to generate additional zeros for better skirt selectivity. The proposed filters, featured with self-packaging advantage, use hybrid spiral structure to realize different electric and magnetic coupling scheme for dual-band, compact size and multiple transmission zeros. In addition, loss reduction approach to reduce both substrate and metal losses is used to achieve insertion loss reduction.

Laser-photometric lump separation of gold-bearing ore

This paper establishes the conditions for selecting the optimal lump separation method based on the values of indicator properties of the ore minerals and demonstrates respective pilot testing results for low-grade quartz-type sulfide gold-bearing ores. The studies have shown the high efficiency of laser-photometric processing of ores with low contents of finely disseminated ore components, for which other methods are ineffective. On the example of ore from the Natalka deposit, it has been shown that acceptable lump separation performance requires division of the original ore into high-grade balance ore (the separation of which would be impractical), low-grade balance ore (to be subjected to lump separation), and an off-balance mineralized mass. Lump processing remains efficient up to ore temperatures of minus 15 °C, if rinsed with 4 °C water. The following concentration indicators were achieved for the lean ore of the process sample taken from the Alternativny section at ore temperatures above minus 15 °С: with the concentrate yield of 20 to 28 %, the gold content increases by 3.0–4.5, with an average level of metal losses in the tailings of approximately 13 %. At ore temperatures down to minus 21 °C, when an opaque ice film with the thickness of over 1 mm is formed on the lump during its screening with washing, metal losses in the separation tailings become 2.0–2.5 times higher. The authors are grateful to the employees of TOMRA, CC of CJSC Polyus Zoloto, Natalka FMS department of OJSC RiM, and FSBI VIMS, who assisted in the pre-concentration technology testing for the ore of the Natalka deposit.

Methanol-based extraction protocol for insoluble and moderately water-soluble nanoparticles in plants to enable characterization by single particle ICP-MS.

The detection and characterization of soluble metal nanoparticles in plant tissues are an analytical challenge, though a scientific necessity for regulating nano-enabled agrichemicals. The efficacy of two extraction methods to prepare plant samples for analysis by single particle ICP-MS, an analytical method enabling both size determination and quantification of nanoparticles (NP), was assessed. A standard enzyme-based extraction was compared to a newly developed methanol-based approach. Au, CuO, and ZnO NPs were extracted from three different plant leaf materials (lettuce, corn, and kale) selected for their agricultural relevance and differing characteristics. The enzyme-based approach was found to be unsuitable because of changes in the recovered NP size distribution of CuO NP. The MeOH-based extraction allowed reproducible extraction of the particle size distribution (PSD) without major alteration caused by the extraction. The type of leaf tissue did not significantly affect the recovered PSD. Total metal losses during the extraction process were largely due to the filtration step prior to analysis by spICP-MS, though this did not significantly affect PSD recovery. The methanol extraction worked with the three different NPs and plants tested and is suitable for studying the fate of labile metal-based nano-enabled agrichemicals.

On the influence of interacting dual defects on the collapse pressure of pipes under external pressure

Metal loss due to corrosion poses a severe threat to the safety of thick-walled pipe in deep-water applications. In the present study, the interaction between defects in the event of collapse under external pressure was examined. Experiments were conducted on a set of small-scale pipes with three families of dual defects positioned longitudinally (LPDD), circumferentially (CPDD), and diagonally (DPDD). The collapse mode of LPDD tubes was dominated by a U-shaped mode, while for CPDD and DPDD families, the prevalent collapsed shape changed from a U-shaped mode to a mode similar to the classical ovalization. Finite element models were also developed to reproduce the experimental results, and good agreement was reached. With the established numerical framework, sensitivity studies on the interaction rules to various parameters of the problem were carried out. It was found that with increasing defect spacing, the normalized collapse pressure increased monotonically for the LPDD group, while the response of CPDD and DPDD families exhibited an increase first, and then a reduction followed it. Overall, the interaction between dual defects was primarily affected by the defect alignment direction, the defect size, as well as the initial ovality and the diameter-to-thickness ratio.

Increasing Efficiency of Copper-Molybdenum Ore Flotation using Measurement of Pulp Absorption Capacity

A promising line in development of reagent consumption automatic control systems is applying data on measuring collector concentration in the pulp aqueous phase. For effective using data on the concentration of the nonionic collector – allyl ester of amylxanthogenic acid – in the process of flotation, the studies were carried out and the method for analyzing its residual concentration in the flotation pulp liquid phase was developed. The developed spectral technique for measuring the concentration of amylxanthogenic acid allyl ester in the pulp aqueous phase showed stable results in the temperature range of 10 to 25 °С, pH range of 8.5 to 11.0. This allowed applying the technique to measuring residual concentration of AeroMX- 5140 collector in the operation of bulk sulphide flotation in copper-molybdenum ore beneficiation. The laboratory tests allowed determining connection between the indicators of residual concentration with the main indicators of copper-molybdenum flotation. The studies showed that increasing the residual concentration of the non-ionic collector occurs with increasing its consumption and pH of the pulp aqueous phase. It is shown that significant increase in metal recoveries is observed at similar residual collector concentrations: for copper, in the range of 0.25 to 0.5 mg/l, and for molybdenum and pyrite iron, at the concentrations from 0.25 to 1 mg/l. The possibility of using the nonionic collector residual concentration as the informational indicator of the flotation process has been substantiated. It is proposed to use the ore absorption capacity in relation to the collector applied as an indicator of the ore grade. It is shown that using this indicator reduces relative variance for the dependences of the yields of individual ore types and increases the accuracy of determining the composition of the processed ore as a mixture of typical ore grades. An algorithm for automated control of the consumption of flotation reagents based on the advanced control of the processed ore elemental and mineral composition was developed and tested at Erdenet GOK processing plant, with the calculation of the pulp absorption capacity in relation to the nonionic collector, including the beneficiation process indicators determination using an economically-oriented optimization criterion. The expected economic effect from the reduction of metal losses amounted to USD 145 thous.

Failure analysis and design of grouted fibre-composite repair system for corroded steel pipes

Grouted fibre-reinforced composite stand-off sleeve repair is a light-weight and easily deployable repair system for steel pipelines with localised metal loss. The effectiveness of this type of repair system is dependent on the load transfer through the grout layer, which is weaker than neighbouring components and susceptible to failure due to stresses developed from applied internal pressure. In this study, three dimensional (3D) Finite Element Analyses (FEA) of a full-scale pipe with different levels of metal loss were implemented to evaluate the failure behaviour and capacity of grouted composite repair system. Steel pipes with a localised defect ranging from 20% to 80% metal loss and repaired using two infill grout systems reinforced with carbon and glass sleeves of different thicknesses were considered. The results indicated that the performance of the repair system is governed by the tensile cracking of the infill grout. A thicker sleeve and higher tensile strength grout delivers higher pipe capacity in the repair system. On the other hand, a high modulus grout provides a more effective load transfer from steel to sleeve. Using a high tensile strength grout, the composite repair system can restore the capacity of the steel pipe with defect up to about 70% metal loss.

PrVO4/SnD NPs as a Nanocatalyst for Carbon Dioxide Fixation to Synthesis Benzimidazoles and 2-Oxazolidinones

Recently CO2 stabilization has received a great deal of attention because of its probable applications as a rich C1 resource and the synthesis of several fine chemicals can be accomplished through this stabilization. In this study, Sn(IV) doping dendritic fibrous nanosilica (SnD) supported PrVO4 nanoparticles as a catalyst (PrVO4/SnD) was synthesized by a in-situ procedure. The SnD with the ratios of Si/Sn in a variety of 6 to 40 were acquired through direct hydrothermal synthesis (DHS), and PrVO4 NPs on the surfaces of SnD were reduced in-situ. X-Ray diffraction (XRD), Scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM), and X-ray energy dispersive spectroscopy (EDS) were deployed for identifying the PrVO4/SnD. It is potentially a highly dynamic catalyst in the stabilization of CO2 for the production of 2-oxazolidinones and benzimidazoles. In addition, the catalyst is very easy to recycle and reuse without significant loss of active site Cu metal. PrVO4/SnD NPs as a nanocatalyst for carbon dioxide fixation to synthesis benzimidazoles and 2-oxazolidinones.

Tunable dual-band terahertz absorber with all-dielectric configuration based on graphene.

In this paper, we theoretically design a dual-band graphene-based terahertz (THz) absorber combining the magnetic resonance with a THz cold mirror without any metallic loss. The absorption spectrum of the all-dielectric THz absorber can be actively manipulated after fabrication due to the tunable conductivity of graphene. After delicate optimization, two ultra-narrow absorption peaks are achieved with respective full width at half maximum (FWHM) of 0.0272 THz and 0.0424 THz. Also, we investigate the effect of geometric parameters on the absorption performance. Coupled mode theory (CMT) is conducted on the dual-band spectrum as an analytic method to confirm the validity of numerical results. Furthermore, physical mechanism is deeply revealed with magnetic and electric field distributions, which demonstrate a totally different principle with traditional plasmonic absorber. Our research provides a significant design guide for developing tunable multi-resonant THz devices based on all-dielectric configuration.

Optimising Metal Content in Platinum Group Metal Ammonia Oxidation Catalysts

Platinum-based knitted gauzes are the most efficient catalysts for the production of nitric oxide, as a precursor to the manufacture of nitric acid and caprolactam. Decades of research and optimisation have resulted in a greater understanding of ammonia oxidation kinetics and associated metal movement within these catalyst packs, along with the development of beneficial binary and ternary alloys. The design of a pack has evolved from the simple addition or removal of metal to modelling the optimal installed metal content and distribution. This review discusses the fundamental kinetics and in situ metal loss for ammonia oxidation catalysts in nitric acid applications and outlines how they can, in conjunction with prevailing platinum group metal (pgm) market conditions and plant key performance indicators (KPIs), influence the optimal catalyst design.

Hf‐W chronology of a macrochondrule from the L5/6 chondrite Northwest Africa 8192

AbstractA large, igneous‐textured, and 2 cm‐sized spherical object from the L5/6 chondrite NWA 8192 was investigated for its chemical composition, petrography, O isotopic composition, and Hf‐W chronology. The petrography and chemical data indicate that this object closely resembles commonly found chondrules in ordinary chondrites and is therefore classified as a “macrochondrule.* As a result of metal loss during its formation, the macrochondrule exhibits elevated Hf/W, which makes it possible to date this object using the short‐lived 182Hf‐182W system. The Hf‐W data provide a two‐stage model age for metal–silicate fractionation of 1.4 ± 0.6 Ma after Ca‐Al‐rich inclusion (CAI) formation, indicating that the macrochondrule formed coevally to normal‐sized chondrules from ordinary chondrites. By contrast, Hf‐W data for metal from the host chondrite yield a younger model age of ~11 Ma after CAIs. This younger age agrees with Hf‐W ages of other type 5–6 ordinary chondrites, and corresponds to the time of cooling below the Hf‐W closure temperature during thermal metamorphism on the parent body. The Hf‐W model age difference between the macrochondrule and the host metal demonstrates that the Hf‐W systematics of the bulk macrochondrule were not disturbed during thermal metamorphism, and therefore, that the formation age of such objects can still be determined even in strongly metamorphosed samples. Collectively, this study illustrates that chondrule formation was not limited to mm‐size objects, implying that the rarity of macrochondrules reflects either that this process was very inefficient, that subsequent nebular size‐sorting decimated large chondrules, or that large precursors were rare.

The Effects of Dual Atmosphere Exposure Duration and Temperature on the Growth of Iron Oxide on Ferritic Stainless Steels

Literature within the past two decades has highlighted the ongoing issue of dual atmosphere corrosion in solid oxide fuel cell (SOFC) systems. This corrosion phenomenon occurs as a result of simultaneous exposure of ferritic stainless steel interconnects to the anodic fuel gas on one side and cathodic air stream on the opposing side. In this, the air-exposed side of the metal interconnect undergoes fast, anomalous corrosion and metal loss in the form of iron oxide overgrowth with whisker and platelet-type morphology. Studies have indicated that the corrosion is favored at lower temperatures in comparison to temperatures above 800 °C. This poses an issue for the current trend of lowering SOFC operating temperatures and utilizing cost-effective ferritic stainless steels as interconnect materials. In this study, the oxidation behavior of two ferritic stainless steels is examined under dual atmosphere exposure conditions. A series of experiments with varying time, temperature, and steel compositions were carried out to better understand the effects of these variables on severity and morphology of corrosion products. A mechanism which describes the localized overgrowth of iron oxide in platelet and whisker form and the porous oxide sub-layer is proposed. The transition from a thin, protective, and dense chromia scale under nominal ambient conditions to porous, non-protective scaling under dual atmosphere conditions will be discussed.

ПРОБЛЕМА ИСПОЛЬЗОВАНИЯ ОТХОДОВ ЛАКОКРАСОЧНЫХ МАТЕРИАЛОВ И ИХ УТИЛИЗАЦИЯ

Актуальность исследования. Коррозия металлов является наиважнейшей проблемой, с которой связаны большие потери металлов. Ежегодно от коррозии безвозвратно теряются сотни тонн металлов, поэтому все исследования, направленные на антикоррозионную защиту металлов, являются целесообразными и актуальными. Цель исследования. Существуют различные методы антикоррозионной защиты металлических деталей, но нет достаточно эффективного метода для конкретных условий антикоррозионной защиты. Целью настоящей работы является использование отходов лакокрасочных материалов для получения антикоррозионных покрытий металлических деталей. Объектом исследования являются отходы лакокрасочных материалов, полученные при окраске автомобилей. Методы: изучение физико-химических свойств отходов; подбор состава для растворения отходов лакокрасочных материалов; разработка рецептуры и получение антикоррозионной мастики; испытание полученного антикоррозионного лакокрасочного покрытия на адгезию, химостойкость, прочность пленки на изгиб, прочность пленки на удар, огнестойкость, морозостойкость; определение наиболее эффективного компонентного и количественного состава полученного покрытия. Выбраны металлические пластинки для нанесения защитного лакокрасочного покрытия, растворы различных соединений для проведения испытаний по определению потери массы опытных металлических образцов Результаты. Разработана и получена мастика на основе госсиполовой смолы и твердых отходов лакокрасочных материалов. Отходы лакокрасочных материалов – потери, получаемые при окраске автомобилей. Госсиполовая смола представляет собой отход масложиркомбината. Полученная мастика прошла испытания в лабораторных условиях по показателям качества в соответствии со стандартами, получены положительные результаты. Проведены эксплуатационные испытания в дорожных условиях, пробег автомобиля составил 12780 км, при исследовании изменения на поверхности покрытия не обнаружены.

On the in-situ characterisation of metastable pitting using 316L stainless steel as a case study

Metastable pitting upon 316L stainless steel was studied herein. The combination of electrochemical testing, in-situ imaging and ex-situ characterisation was carried out to address the following questions: Does each metastable pit site correspond to a single current transient or do multiple metastable pits occur at the same site? Is each recorded current transient a unique individual metastable pitting event? Does the calculated metal loss from electrochemical testing reconcile to physical damage? The results herein respond to these questions, and additionally, a user tool for analysis of metastable pitting is also presented herein.

Ultrawideband terahertz absorber with a graphene-loaded dielectric hemi-ellipsoid

We herein present a high-performance ultrawideband terahertz absorber with a silicon hemi-ellipsoid (SHE) on a monolayer graphene that is separated by a dielectric spacer from a bottom metal reflector. The constitution of the absorber, which includes dielectric-mode structures and unstructured monolayer graphene, can minimize undesired optical losses in metals and avoid graphene processing. The absorber achieved an ultrawide absorption bandwidth from 2 THz to more than 10 THz with an average absorption of 95.72%, and the relative bandwidth is 133%. The excellent absorption properties are owing to the presence of graphene and the shape morphing of the SHE, in which multiple discrete graphene plasmon resonances (GPRs) and continuous multimode Fabry-Perot resonances (FPRs) can be excited. By coupling the GPRs and FPRs, the absorption spectrum is extended and smoothed to realize an ultrawideband absorber. The incident angular insensitivity within 50° of the absorber is discussed. The results will shed light on the better performance of terahertz trapping, imaging, communication and detection.

Hydrometallurgical processing of waste multilayer ceramic capacitors (MLCCs) to recover silver and palladium

Present paper reports an application oriented approach to recover precious metals such as silver (Ag) and palladium (Pd) from multilayer ceramic capacitors (MLCCs) of waste printed circuit boards (PCBs). These capacitors are being widely used in modern electronic gadgets to provide advance features as well as to enhance their performance. Due to the generation of large amount of e-waste as well as the loss of precious metals, a sincere R&D effort has been made to develop a process for the recovery of Ag and Pd from waste MLCCs. Initially, the MLCCs were depopulated from the PCBs by de-soldering using thermal treatment. Further, the depopulated material was pulverised to get homogeneous fine powder of MLCCs, which contained 0.14% Pd, 1.08% Ag, 1.76% Cu and 11.1% Ni. First of all Ni was removed/recovered selectively using two stages of leaching at optimized condition i.e. 2 M HCl, temperature 75 °C and pulp density 100 g/L. The obtained leached residue was washed, dried and further leached to get 99.99% Ag and Pd both in solution using 4 M HNO3, temperature 80 °C, pulp density 100 g/L and mixing time 1 h. From the obtained leach liquor, salt of Ag (purity 99.99%) was selectively recovered/precipitated using KCl. Further, Cu was extracted from the Ag depleted solution using LIX 84IC leaving Pd in the raffinate, which was evaporated to get pure Pd salt. The developed flow-sheet has potential to be commercialized after scale up trials.