Aluminum Loss Research Articles

Synthesis of ultra-fine and controllable size distribution nanocrystalline MgAl2O4 powders and ascertainment of aluminum loss by introducing inert atmosphere pre-calcination during combustion

Nanocrystalline magnesium aluminate spinel (MgAl2O4) powders were synthesized in this study by employing a modified nitrate–citrate combustion route, in which the heat treatment was continuously performed by two separate processes. One process was in nitrogen during the carbonization of the precursors, and the other was subsequently in air. This can greatly decrease the heat release during the combustion process. X-ray diffraction and high-resolution transmission electron microscopy, differential scanning calorimetry, thermogravimetry, infrared spectroscopy, and inductively coupled plasma atomic emission spectrometer were utilized to reveal the reaction process and characterize the physical properties of precursors and powders. To achieve well-crystallized spinel powders with smallest possible and controllable crystallite sizes, the effect of carbonization in nitrogen on the calcined spinel powders was investigated in detail. The introduction of the inert atmosphere at the pre-calcination stage, with appropriate temperature and holding time, allowed ultra-fine, well-crystallized and size-controllable MgAl2O4 powders with average crystallite sizes of 5–25 nm to be obtained. Despite the benefit from the pre-calcination in nitrogen, it was found that the stoichiometry of precursors can be compromised due to the loss of aluminum during the heat treatment in N2 as the temperature was too high (>900 °C) with sufficient holding time. The mechanism of the carbothermal reduction was investigated in this study. By introducing inert atmosphere pre-calcination combustion, ultra-fine well-crystallized and crystalline size-controllable MgAl2O4 spinel powders were thus obtained.

Light Metals Chips Recycling by Plastic Consolidation

In this work, hot extrusion of light metal scraps as a new way of plastic consolidation will be presented. This kind of material recovering is a promising alternative for conventional recycling processes. Nowadays discards from machining of semi-finished products are being recycled throughout re-melting processes. However, due to its significant susceptibility to oxidation most of the chips and scraps are burnt during the melting process. It has been already recognized that aluminum losses connected with this operation can reach from 40% to 50%. A technology that has been presented in this work combines cold compaction and hot extrusion of 413.0 aluminum alloy scraps. It was found that quality of as-extruded rods depends strongly on extrusion conditions. Higher extrusion speed leads to higher quality of rods surface. Additionally brittle Si and Al-Fe-Si particles increases overall mechanical properties in comparison to its industrial counterpart.

FRET enhancement in aluminum zero-mode waveguides.

Zero-mode waveguides (ZMWs) can confine light into attoliter volumes, which enables single molecule fluorescence experiments at physiological micromolar concentrations. Of the fluorescence spectroscopy techniques that can be enhanced by ZMWs, Förster resonance energy transfer (FRET) is one of the most widely used in life sciences. Combining zero-mode waveguides with FRET provides new opportunities to investigate biochemical structures or follow interaction dynamics at micromolar concentrations with single-molecule resolution. However, prior to any quantitative FRET analysis on biological samples, it is crucial to establish first the influence of the ZMW on the FRET process. Here, we quantify the FRET rates and efficiencies between individual donor-acceptor fluorophore pairs that diffuse into aluminum zero-mode waveguides. Aluminum ZMWs are important structures thanks to their commercial availability and the large amount of literature that describe their use for single-molecule fluorescence spectroscopy. We also compared the results between ZMWs milled in gold and aluminum, and found that although gold has a stronger influence on the decay rates, the lower losses of aluminum in the green spectral region provide larger fluorescence brightness enhancement factors. For both aluminum and gold ZMWs, we observed that the FRET rate scales linearly with the isolated donor decay rate and the local density of optical states. Detailed information about FRET in ZMWs unlocks their application as new devices for enhanced single-molecule FRET at physiological concentrations.

Long-term effects of gap creation and lime application on element input and output in a European beech (Fagus sylvatica L.) forest

Four gaps of 30 m diameter were cut in a mature European beech (Fagus sylvatica L.) forest in 1989. In two of the gaps and their surrounding areas, dolomite lime (3 t ha−1) was applied. The study was designed to examine the long-term effects of lime application and canopy removal on element input via throughfall and output in seepage water at 80 cm depth in this European beech forest. Throughfall and seepage water were collected in the unlimed gap center, the limed gap center and the undisturbed beech stand in 1991, 1992, 1993, 1996 and 2012. The canopy opening increased the seepage water acidity from 1991 to 1996. The pH values of the seepage water were higher in the limed gaps than in the unlimed gaps during the five study periods. The amount of annual throughfall and of seepage water were higher in the gaps during the study period; in 2012, the annual amounts of seepage water were significantly higher in the gaps than in the closed stand, whereas the input of most elements decreased from 1991 to 2012. The seepage water in the unlimed gaps had higher nitrate nitrogen (NO3-N) concentrations, but lower sulfate sulfur (SO4-S) concentrations than in the limed gaps in 1991, 1992, 1993 and 1996. The amount of leaching NO3-N and SO4-S in 2012 was, however, significantly higher in the limed gaps than in the unlimed gaps, while the input of nitrogen (N) and SO4-S was significantly lower in the limed gaps than in the closed stand. In general, the annual amounts of element input via throughfall were higher in the closed stand than in the gaps. However, the element output through leaching was much higher in the gap centers than in the closed stand. The net losses of aluminum (Al), calcium (Ca), magnesium (Mg) and manganese (Mn) were higher in the unlimed gaps than in the limed gaps and the closed stand in 1991. In 2012, 23 years after liming and canopy opening, the effects of gaps and liming, and the interaction of gap and liming on element leaching, were still significant compared to the untreated stand. Overall, canopy opening reduced N, sulfate, Al, and base cation deposition in the long run. Canopy opening in combination with liming affected the seepage water acidity and the leaching losses of base cations up to 23 years after canopy removal and liming in this European beech forest.

Optimizing and developing a continuous separation system for the wet process separation of aluminum and polyethylene in aseptic composite packaging waste

The consumption of milk in China is increasing as living standards rapidly improve, and huge amounts of aseptic composite milk packaging waste are being generated. Aseptic composite packaging is composed of paper, polyethylene, and aluminum. It is difficult to separate the polyethylene and aluminum, so most of the waste is currently sent to landfill or incinerated with other municipal solid waste, meaning that enormous amounts of resources are wasted. A wet process technique for separating the aluminum and polyethylene from the composite materials after the paper had been removed from the original packaging waste was studied. The separation efficiency achieved using different separation reagents was compared, different separation mechanisms were explored, and the impacts of a range of parameters, such as the reagent concentration, temperature, and liquid–solid ratio, on the separation time and aluminum loss ratio were studied. Methanoic acid was found to be the optimal separation reagent, and the suitable conditions were a reagent concentration of 2–4mol/L, a temperature of 60–80°C, and a liquid–solid ratio of 30L/kg. These conditions allowed aluminum and polyethylene to be separated in less than 30min, with an aluminum loss ratio of less than 3%. A mass balance was produced for the aluminum–polyethylene separation system, and control technique was developed to keep the ion concentrations in the reaction system stable. This allowed a continuous industrial-scale process for separating aluminum and polyethylene to be developed, and a demonstration facility with a capacity of 50t/d was built. The demonstration facility gave polyethylene and aluminum recovery rates of more than 98% and more than 72%, respectively. Separating 1t of aluminum–polyethylene composite packaging material gave a profit of 1769 Yuan, meaning that an effective method for recycling aseptic composite packaging waste was achieved.

Loss of Aluminium during the Process of Ti-Al Alloy Melting in VIM Furnace

Titanium alloys belong to a group of the most advanced metal materials with increasing applications observed in recent years, mainly in the aircraft, shipbuilding, automotive and chemical industries as well as in medicine. In the paper, results of the study on changes in aluminium content in binary Ti-Al alloys during smelting in the vacuum induction melting (VIM) furnace are presented. The experiments were performed at 5 Pa and 1000 Pa, 1973 K and 2023 K. The investigations were conducted for alloys containing up to 49%mass Al. Each experiment began with loading an alloy sample (about 1000 g) into the graphite crucible placed in the induction coil of the furnace. After closing the furnace chamber, the pre-specified vacuum was generated with the use of a pump system. When the pressure level was stabilised, the crucible was heated up to the required temperature and the metal bath was held for 600 sec. During each smelting experiment, metal samples were collected and subjected to a chemical analysis. The Al loss rate in each experiment was not higher than 21%; it increased with temperature and reduced pressure in the device. It is assumed that the observed loss of aluminium during smelting is the effect of evaporation. The obtained values of Al concentration in the investigated alloys ensured that the aluminium overall mass transfer coefficient in the process could be estimated. The values of overall mass transfer coefficient were 0.88 to 1.66×10-5 [m·s-1]. Lack of clear effects of the alloy composition on the analysed process rate proves that it is not controlled by mass transfer in the liquid phase.

Hierarchization of USY Zeolite by NH4OH. A Postsynthetic Process Investigated by NMR and XRD

Ammonia treatment of USY zeolite has led to a new hierarchical material. The local and global structural changes during the transformation have been monitored by XRD and by 1H, 29Si, and 27Al solid-state NMR. A wealth of 1D and 2D NMR protocols were applied, including 1H DQ–SQ (double-quantum–single-quantum), 27Al MQMAS (multiple-quantum magic angle spinning), 29Si MAS (magic angle spinning) and CPMAS (cross-polarization magic angle spinning), and 1H–29Si HETCOR (heteronuclear correlation). The effects of aqueous ammonia treatment, different thermal post-treatments, and rehydration were studied. An increasing loss of crystallinity was observed upon increasing duration of ammonia treatment. Under the experimental conditions, a few percent of silica was lost into solution and no loss of aluminum was observed. However, increasing numbers of silanol groups were detected. The progressive transformation induces formation of mesopores, reduction of the fraction of the sample exhibiting Bragg crystallinity, and apparition of a dense, amorphous aluminosilicate phase. The latter contains ammonium ions and strongly bound water, both of which are resistant to thermal decomposition up to 350 °C. After about 24 h of treatment, the zeolite fraction is completely transformed into the amorphous phase. At intermediate stages, a complex hierarchical material is obtained with mesopores and zeolitic micropores next to a dense amorphous aluminosilicate, containing ammonium ions, highly structured water, and silanol nests.

Selective electron beam melting of Ti–48Al–2Nb–2Cr: Microstructure and aluminium loss

In the present paper a broad parameter window for processing Ti–48Al–2Cr–2Nb by selective electron beam melting is investigated. Data for the aluminium loss during the process in relation to used beam parameters and process strategies for its minimisation are presented. Al losses as low as 0.5 at% were achieved. Using different beam parameters a wide range of microstructures from lamellar to massively transformed γ could be realized. This finding in principle gives the opportunity to locally adjust the microstructure of net or near-net-shape parts from TiAl during the process.

Effect of TiO2addition to LF refining slag on the Ti, Al, and cleanliness of Ti-stabilized stainless steel

The influence of TiO2 addition to LF refining slag on Ti-stabilized stainless steel was evaluated using a vacuum induction furnace at 1873 K. The effect of CaO-SiO2 -MgO-Al2 O3 basic slags with different TiO2 contents on the titanium loss, aluminum loss and total oxygen content in the steel was studied. It was observed that the oxidation rate of Ti first decreases and then increases with the increase in the content of TiO2 in slag and reaches the minimum when 8%TiO2 is added to the slag. However, the change in the oxidation rate of Al shows the opposite tendency. The total oxygen in the molten steel remains unchanged with time when 8%TiO2 is added to the slag, and the total oxygen of the others increases monotonically with time. The activities of TiO2 and Al2 O3 from the calculation of the ion and molecule coexistence theory (IMCT) in the initial slag present the same change tendency, and both first increase and then decrease with the gradual increase in TiO2 in the slag and reach the maximum when 8%TiO2 is added to the slag. The results of a kinetic analysis showed that the rate-determining step of the oxidation of Ti in the steel is the mass transfer on the slag side, and the rate-determining step of the oxidation of Al in the steel is the mass transfer on the metal side.

Effect of Process Parameters on Microstructure of TiAl Alloy Produced by Electron Beam Selective Melting

Pre-alloyed Ti-47Al-2Cr-2Nb powder was utilized to fabricate samples via electron beam selective melting. The microstructures of as-built components were characterized by optical microscopy, scanning microscopy and X-ray diffraction, while an electronic dispersive spectrometer was employed to study the chemical compositions. It is worth noting that the atomic percentage of aluminium decreased along with the increase of energy input. There appeared to be an element loss of aluminium up to 15% at the highest energy input. The microstructures consisted of lamellar α2-Ti3Al)/γ-TiAl, basket-weave α2 (Ti3Al) and B2 phase. With varied melting beam currents, different phase transformations resulted from different thermal cycles and varied element losses of aluminium. γ-TiAl was the main phase of Sample-1 with the lowest energy input, while α2-Ti3Al was the main phase of Sample-4 with the highest energy input. The thickness of lamellar α2 decreased as the cooling rate increased due to the increasing energy input.

ALUMINIUM LOOS IN THE PROCESS OF Ti-6Al-7Nb SMELTING

In the paper, results of experimental smelting of the Ti-6Al-7Nb alloy in a vacuum induction furnace are presented. The experiments were performed at 5-1000 Pa and 1973-2023 K. For the analysed alloy, a significant impact of pressure on aluminium loss was observed. Pressure reduction in the device from 1000 Pa to 5 Pa was accompanied by Aluminium content decrease from the initial value of 5.5 % mass to a value even below 3.2 % mass. Moreover, aluminium elimination was enhanced when the smelting temperature increased. Additionally, values of a so-called evaporation coefficient (Ω) were determined. In terms of titanium and niobium, ΩAl/Ti and ΩAl/Nb values suggest that, thermodynamically, aluminium loss may result from its intense evaporation from the investigated alloy.

INVESTIGATION OF THE ROLE OF LIME UNDER SLAGGING AND INERT-GAS SECONDARY STEEL REFINING

It is shown that the creation of such technologies is caused by the necessity of making standard high-quality steel in composition and temperature. The secondary steel refining provides these conditions and, consequently, the efficient operation of the steel continuous casting plants. The commercially proven experimental results on the lime consumption effect on the slagging processes in the electric arc furnaces and on the further secondary refining in the ‘ladle-furnace’ units are presented. A flow chart of the complex processing “Electric Arc Furnace → Secondary Refining → Steel Continuous Casting Plant” is offered. It eliminates the increase of the slag oxidation degree under bottom blowing, aluminum loss in the bucket, and the increase of the oxygen concentration in the liquid steel. The proposed technology solutions to optimize the lime flow, slag adjustment, and to regulate the steel ladle stirring regime have permitted to raise the basic technical and economic indicators of the steelmaking at Oskolsky electrometallurgical works.

Alloying-Element Loss During High-Temperature Processing of a Nickel-Base Superalloy

The effect of exposure at temperatures commonly used for wrought processing/heat treatment of nickel-base superalloys on the loss of alloying elements at the free surface has been determined. For this purpose, LSHR superalloy samples were exposed at 1408 K (1135 °C) for 0.25 to 4 hours in a vacuum or air furnace. Samples heat treated in the air furnace were either bare or enclosed in quartz capsules that had been evacuated or backfilled with argon. Following heat treatment, the alloy composition as a function of depth below the surface was determined by wavelength dispersive spectroscopy. Samples that had been heat treated in the vacuum furnace exhibited significant depletion of only chromium, a behavior explained on the basis of its high activity in nickel solid solution and corresponding rapid rate of evaporation. By contrast, samples heat treated in air exhibited an irregular scale at the surface and an underlying grain-coarsened, gamma-prime-depleted metal layer lean in aluminum, titanium, and chromium. A yet different behavior characterized primarily by aluminum loss at the surface was noted for samples that had been heat treated in evacuated or argon-backfilled capsules. These observations were interpreted in the context of a reaction between the quartz capsule and the aluminum evaporant.

Evolution of carbides and chromium depletion profiles during oxidation of Alloy 602 CA

The microstructure evolution in carbide strengthened Alloy 602 CA during exposure to a synthetic flue gas (N2–2.5%O2–8.6%H2O–16.4%CO2) at 1100°C has been studied. The chromium and aluminium loss resulted in a chromium depleted alloy subsurface area and the dissolution of the carbides within this area. An increase of the carbide fraction in the sample core was observed and quantified. Phase equilibria calculations revealed that the depletion of aluminium as well as that of chromium triggers carbon to leave the depleted area. The overall carbon depletion in that area corresponded to the observed increase in carbide fraction in the sample core.

Evaluation of Sulfur Addition to the High Basicity Slag on the Sulfur, Aluminum, and Cleanliness of High Sulfur Al‐Killed Molten Steel

AbstractIn the present work, the influence of sulfur addition to the high basicity slag on the Al‐killed molten steel with high sulfur content was investigated by using a vacuum induction furnace at 1873 K in MgO crucibles. CaO–SiO2–Al2O3–MgO–CaS slags were used to study the effect of high basicity slags with different CaS contents on sulfur loss, aluminum loss, and total oxygen content in the molten steel. It is shown that the sulfur content in the molten steel decreased with the time, and the addition of CaS into the slag can reduce the sulfur loss in the molten steel. Moreover, there was a decreasing tendency of the aluminum content in the molten steel with the time, and the addition of CaS into the slag can reduce the aluminum loss in the molten steel. Total oxygen content in the molten steel first increased and then decreased with the time when no CaS was added into the slag. However, it decreased monotonically with the time when the addition of CaS was made into the slag.

Historical evolution of anthropogenic aluminum stocks and flows in Italy

Dynamic stocks and flows analysis was applied to the anthropogenic aluminum cycle in Italy in order to detect and quantify metal flows and in-use stocks over the years 1947–2009. The model utilized a top-down approach, including data for production, consumption, loss, and trade flows of aluminum. Seven end-use markets were considered, namely buildings and construction, transportation, consumer durables, machinery and equipment, electrical engineering, containers and packaging, and miscellaneous appliance types. The results of this dynamic stocks and flows analysis model quantified the contemporary anthropogenic reservoirs (or in-use stocks) of aluminum at about 320kg per capita, mainly embedded within the transportation and building and construction sectors. Cumulative in-use stock represents approximately 11 years of supply at current usage rates (about 20Mt versus 1.7Mt/year), implying significant potential for recycling in the future as this stock comes out of use. Flow analysis revealed that Italy imports mainly unwrought aluminum and exports final products, while the main material losses occur during alumina refining and collection of old scrap: specifically, containers and packaging have the highest old scrap generation rate, but for the lowest recovery rate (50%). Increasing support to collection of scrap and initiatives oriented to aluminum recovery specifically would allow Italy to increase its reliance on domestic material, and may also allow a decline of the country import-dependence on primary sources. The dynamic stocks and flows model created here provides a quantitative historical record of the aluminum required by Italian society during important periods of development and provides guidance for future decision-making around the use of domestic secondary resources.

Aluminum Loss Analysis and Evaluation of Squirrel Induction Motor

In this paper, rotor bar Aluminum Loss of Squirrel Induction Motor running in steady state with full load is investigated. Multi-layered analytical model of rotor bar is employed to analyze the Aluminum loss generated by harmonic current. This model divides the rotor bar into a series of sub-layers with resistance remained constant in each sub-layer considering the skin effect. The bar loss in every layer are analyzed and calculated to get total loss of the whole rotor bar. The finite element analysis is used to verify the results of multi-layered model. A prototype motor Y160L-4 is calculated by combining proposed method and finite element method. The losses with different number of rotor slots are also calculated and discussed. It is useful for loss reduction and efficiency improvement in induction motor design and optimal applications.

Abrasive Wear Performance of Hot-Dipping Al-Mn Alloy Coatings on Q235

The Q235 steel was modified by hot-dip-aluminizing technique, and Al-Mn alloy layer was obtained on the steel surface. Scan electron microscopy (SEM), X-ray diffraction (XRD) and abrasive wear tester were used to investigate the microstructure and wear performance of the Al-Mn alloy coatings. The results show that the surface of the obtained pure aluminum coatings is acicular, while blocks Al-Mn compounds phase exists in Al-Mn alloys layer, and the Al-Mn alloy layer is composed of Al, FeAl3, Fe2Al5 and MnAl6 phases. The experimental results showed that wear weight loss of aluminum coating is more than Q235 steel. However, after manganese added to the aluminum, Al-Mn alloy coating abrasion wear loss of weight far below the Q235 steel and aluminum coating. And weight loss increases along with Mn content decreases. When worn after 100 h, Al-13% wtMn wear alloy coating weight loss of 45% of Q235 steel, aluminum coating of 35%. So the hot-dipping Al-Mn alloy layer has excellent abrasive wear resistance.

Dealumination of HZSM-5 via steam-treatment

Two distinct locations for tetrahedral aluminum in HZSM-5 have been identified, showing bond angles of 150° and 155° T–O–T, respectively. The former site is more abundant and has been indirectly associated with aluminum in isolated positions. Upon steaming its concentration decreases, following a first order rate law and leading to the formation of tetrahedrally coordinated extra-lattice aluminum as well as to invisible extra-lattice aluminum. The latter is speculated to be also tetrahedrally coordinated and kinetically linked to the visible portion of the extra-lattice aluminum. Both types of extra-lattice aluminum neutralize lattice charge and lead to a decrease of the concentration of bridging Si–OH–Al groups, which is initially more pronounced than the loss of lattice aluminum. With steaming duration the concentration of Brønsted acid sites stabilizes indicating that the extra-lattice aluminum atoms begin to form larger clusters at a rate equivalent to the rate of dealumination. The lattice aluminum with the more obtuse T–O–T angle is stable under the steaming conditions chosen. As its concentration is nearly equivalent to the concentration of aluminum sites sufficiently close to exchange Co2+ ions, it is inferred that aluminum resisting dealumination constitutes these sites.

Reoxidation of Al‐Killed Steel by Ca(OH)2 in the High Basicity Slag

AbstractIn the present work, reoxidation of Al‐killed steel by Ca(OH)2 in high basicity slag was investigated by using laboratory experiments at 1873 K in MgO crucibles with various amount of Ca(OH)2 addition into slag. The CaO–SiO2–Al2O3–MgO–Ca(OH)2 slags were used to study the effect of Ca(OH)2 on total oxygen content, aluminum loss, and FeO content in the slag. It was shown that total oxygen content decreased with the time when no Ca(OH)2 was added into the slag, but it first increased and then decreased with the time when the addition of Ca(OH)2 was made. Moreover, aluminum loss and FeO content in the slag increased with increasing Ca(OH)2 content.