High Purity Aluminum Research Articles

Preparation of 99.6 % alumina ceramic substrates with high thermal conductivity by tape casting and warm pressing process

High-purity alumina ceramic substrates have drawn immense attention because of its high strength and hardness, as well as good chemical stability. However, the high sintering temperature and low product yield are significant barriers to the preparation of high-purity alumina ceramic substrates. In this study, modified alumina nanoparticles are used to fabricate high-purity alumina ceramic substrates under pressureless sintering via a tape casting–warm pressing process. The influences of powder modification, forming processes, sintering temperature, and powder particle size on the microstructure, mechanical properties, and thermal properties of the fabricated alumina ceramic substrates are investigated. The experimental results show that tape casting–warm pressing significantly improves the microstructure and density of the green tape and ceramic substrate. As the particle size decreases from 1 μm to 100 nm, the grain arrangement of the ceramic substrate gradually becomes more compact. The smooth ceramic substrate prepared with 100 nm modified powders achieves a relative density of 98.85 % when sintered at 1550 °C, while the average roughness is only 20.0 nm. Especially, the 99.6 % alumina ceramic substrate exhibits excellent physical and mechanical properties, with a thermal conductivity of 37.39 W/(m·K) and fracture toughness of 4.68 MPa m1/2, making it highly suitable for application in the power integrated-circuit field.

Properties of Wedge Wire Bonded Connection Between a Composite Copper Core Aluminum Shell Wire and an 18650 Cylindrical Lithium-Ion Battery Cell.

Wedge wire bonding is a solid-state joining process that uses ultrasonic vibrations in combination with compression of the materials to establish an electrical connection. In the battery industry, this process is used to interconnect cylindrical battery cells due to its ease of implementation, high flexibility and ease of automation. Wire materials typically used in battery pack manufacturing are pure or alloyed aluminum and copper. While copper wires possess better electrical properties, the force used in the bonding process can lead to cell isolator damage and cell thermal runaway. This is an unacceptable result of the bonding process and has led to the development of new types of composite wires containing a copper core embedded in an aluminum shell. This material has the advantage of high copper electrical and thermal conductivity combined with less aggressive bonding parameters of the aluminum wire. The aim of this study was to establish a process window for the wedge wire bonding of 400 µm composite copper-aluminum Heraeus CucorAl Plus wire on the surface of a BAK 18650 battery cell. This study was conducted using a Hesse Bondjet BJ985 CNC wire bonder fitted with an RBK03 bond head designed for the bonding of copper wires. The methods used in this study included light and scanning electron microscopy of bond and battery cell cross-sections, shear testing on the XYZtec Sigma bond tester system, and energy dispersive spectroscopy. The results were compared with a previous study conducted using a wire of the same diameter and made out of high-purity aluminum.

Influence of green solvents on the recovery of cathode active materials from electrode scraps: A comparative study

Direct recycling of cathode materials from spent Li-ion batteries (LIBs) or electrode scraps necessitates the efficient recovery of active materials from the aluminum foil. The variability in electrode types and recovery processes across previous studies complicates the comparative assessment of the recovery performance of green solvents. In this study, we evaluated the performance of three green solvents—triethyl phosphate (TEP), dihydrolevoglucosenone (Cyrene), and propylene carbonate (PC)—in recovering valuable active materials from industrial-grade cathode scraps. Using ultrasonication, we developed a standardized, energy-efficient recovery process that eliminated the need for conventional stirring and achieved complete cathode delamination from the aluminum foil. Furthermore, we successfully recovered the used green solvents after the process, ensuring their reuse and supporting a circular economy. The recovered materials retained their original morphology, chemical composition, and crystalline structure; however, the presence of surface impurities varied significantly depending on the green solvent used. These impurities had a considerable impact on the electrochemical performance of the recovered materials. TEP and PC yielded high-purity active materials and aluminum foils suitable for reuse or direct recycling, while Cyrene resulted in substantial residues of PVDF/solvent, requiring additional post-processing. Additionally, the recyclability of these green solvents was influenced by their solubility power for PVDF. This study provides valuable insights into the green solvent-based recycling process, laying the groundwork for future sustainable practices in LIB recycling.

Delamination and Evaluation of Multilayer PE/Al/PET Packaging Waste Separated Using a Hydrophobic Deep Eutectic Solvent.

This research concerns the development and implementation of ground-breaking strategies for improving the sorting, separation, and recycling of common flexible laminate packaging materials. Such packaging laminates incorporate different functional materials in order to achieve the desired mechanical performance and barrier properties. Common components include poly(ethylene) (PE), poly(propylene) (PP), and poly(ethylene terephthalate) (PET), as well as valuable barrier materials such as poly(vinyl alcohol) (PVOH) and aluminium (Al) foils. Although widely used for the protection and preservation of food produce, such packaging materials present significant challenges for established recycling infrastructure and, therefore, to our future ambitions for a circular economy. Experience from the field of ionic liquids (ILs) and deep eutectic solvents (DESs) has been leveraged to develop novel green solvent systems that delaminate multilayer packaging materials to facilitate the separation and recovery of high-purity commodity plastics and aluminium. This research focuses on the development of a hydrophobic DES and the application of a Design of Experiments (DoE) methodology to investigate the effects of process parameters on the delamination of PE/Al/PET laminate packaging films. Key variables including temperature, time, loading, flake size, and perforations were assessed at laboratory scale using a 1 L filter reactor vessel. The results demonstrate that efficient separation of PE, Al, and PET can be achieved with high yields for material and solvent recovery. Recovered plastic films were subsequently characterised via Fourier-transform infra-red (FTIR) spectroscopy, Differential Scanning Calorimetry (DSC) and Thermogravimetric Analysis (TGA) to qualify the quality of plastics for reuse.

Synthesis and characterisation of high-purity alumina achieved through a dip coating process

ABSTRACT This study focuses on the synthesis of alumina using a modified citrate method. The chelation process involved thermal activation through biphasic drops, employing the hydrated aluminium nitrate precursor and citric acid complex. The thermal behaviour of the resulting gel was investigated using DSC/TGA followed by FTIR, which revealed absorption bands at distinct temperatures leading up to the formation of white crystallised alumina powder at 1000°C. Structural analysis via XRD parameters indicated that the obtained sample is refined in the hexagonal system with the R-3C space group. SEM observations demonstrated morphology akin to an overlapping hive, highlighting significant stoichiometric purity. The semi-colloidal sol was applied in a dip-coating method to reinforce the matrix of a steel substrate, specifically E335. SEM-EDS analyses revealed the adhesion recorded as a brittle intermetallic phase. Additionally, a transformation of 22% haematite to magnetite was observed under the conditions of coating.

EXTRACTION OF PURE ALUMINA FROM KAOLIN: A REVIEW

This study demonstrated that high-purity alumina can be generated from kaolin using various methods. It examined different leaching techniques, considering the size and percentage recovery of alumina by weight in selected kaolin samples, the calcination temperature, and the molar concentration of acids over time. Additionally, it analyzed the characteristics of several kaolin sources in Nigeria with the aim of extracting alumina. The research indicates that Nigerian kaolinite clay typically contains 22–40% alumina by weight. However, leaching kaolin yielded alumina with a purity of 60–97 wt%, with particle sizes ranging from 16 to 177 nm. Alumina derived from kaolin is deemed beneficial for manufacturing refractory materials, water purification, and biomedical applications.

High purity alumina production by leaching-ion exchange process: Design and flowchart proposal

Growing demand for high-purity Al2O3 for the electronic market and green energy production, allied with the need to decrease waste generation and dam use, will impact the future of mining, and new processes should be developed. The present study aimed to develop a hydrometallurgical process to obtain high-purity Al2O3 from bauxite. Among the samples studied, BX03 had the highest Al2O3 (63.8 %) and lowest Fe2O3 content (4.3 %). Different acids were evaluated – H2SO4, HCl, HNO3, and H3PO4 – and the H2SO4 reaction achieved all Al leaching with the best technical–economic analysis (TEA). Purification experiments were carried out with ion exchange resins in batch reactions. The best purification parameters were 4 h of contacting time and mass of resin/volume of solution ratio as 1/10 at 45 °C in two stages. The iminodiacetate resin (Lewatit TP 207) achieved the best results and removed all Fe ions without losses. High-purity Al2O3 was further obtained by precipitation with NH4OH after calcination. Considering the leaching step costs, the proposed process may achieve up to US$ 63,022.91 in profit.

Effect of Dislocation Density on the Dynamic Strength of Aluminium

The effects of cold work on dynamic flow strength is studied through measurements of dislocation density and elastic precursor attenuation in shocked aluminium. High-purity aluminium and Al 6082 alloy samples are subjected to up to three passes of rotary swaging, a severe plastic deformation (SPD) technique, in order to produce large variations in starting material conditions. Detailed material characterisation is performed using electron backscatter diffraction (EBSD) and transmission electron microscopy (TEM) to determine the initial dislocation density, texture, grain boundary density and misorientation distribution. Variations in dynamic strength are studied through the evolution of the elastic precursor amplitude with propagation distance in specimens with thicknesses between 0.2 and 1 mm, shock loaded to impact stresses of about 4.6 GPa. It is shown that dynamic strength decreases with increasing initial dislocation density in both materials, demonstrating rare, quantified measurements of a reversal in the effect of dislocation density on yield strength at strain rates around 104 s-1 and above.

Microstructure and hardness of two-step reverse-polarity flash sintered high-purity Al2O3 ceramics

In this work, high-purity alumina ceramics were prepared by using two-step reverse polarity flash sintering (PR-FS). The effects of the time distribution between the first flash and the second flash on microstructure and hardness were studied. The results show that compared to the conventional DC flash sintered alumina, the RP–FS–ed samples exhibited more uniform-microstructure, finer grains, higher relative density, and higher hardness. The underlying mechanism for such more homogeneous microstructure was related to uniform distribution of point defects under effect of reverse polarity. Two-step reverse polarity flash sintering method offers a great potential in obtaining highly densified alumina ceramics with homogeneous microstructure.

A Rapid, Efficient Method for Anodic Aluminum Oxide Membrane Room-Temperature Multi-Detachment from Commercial 1050 Aluminum Alloy.

For commercial processes, through-hole AAO membranes are fabricated from high-purity aluminum by chemical etching. However, this method has the disadvantages of using heavy-metal solutions, creating large amounts of material waste, and leading to an irregular pore structure. Through-hole porous alumina membrane fabrication has been widely investigated due to applications in filters, nanomaterial synthesis, and surface-enhanced Raman scattering. There are several means to obtain freestanding through-hole AAO membranes, but a fast, low-cost, and repetitive process to create complete, high-quality membranes has not yet been established. Here, we propose a rapid and efficient method for the multi-detachment of an AAO membrane at room temperature by integrating the one-time potentiostatic (OTP) method and two-step electrochemical polishing. Economical commercial AA1050 was used instead of traditional high-cost high-purity aluminum for AAO membrane fabrication at 25 °C. The OTP method, which is a single-step process, was applied to achieve a high-quality membrane with unimodal pore distribution and diameters between 35 and 40 nm, maintaining a high consistency over five repetitions. To repeatedly detach the AAO membrane, two-step electrochemical polishing was developed to minimize damage on the AA1050 substrate caused by membrane separation. The mechanism for creating AAO membranes using the OTP method can be divided into three major components, including the Joule heating effect, the dissolution of the barrier layer, and stress effects. The stress is attributed to two factors: bubble formation and the difference in the coefficient of thermal expansion between the AAO membrane and the Al substrate. This highly efficient AAO membrane detachment method will facilitate the rapid production and applications of AAO films.

Deformation behavior of high purity aluminum single crystals under repeated biaxial compressions

Deformation behavior of high purity aluminum single crystals under repeated biaxial compressions

Strain rate effects on fragment morphology of ceramic alumina: A synchrotron-based study

Dynamic (600–1000 s−1) and quasi-static (0.001–0.01 s−1) compression experiments are conducted on a high-purity alumina ceramic using a split Hopkinson pressure bar and a material test system, respectively. The postmortem fragments of ceramic samples at different strain rates are then characterized via synchrotron micro computed tomography (CT). The three-dimensional (3D) morphologies of fragments are quantified using the gyration tensor analysis after proper segmentation of CT images. The mean fragment size decreases in a power-law form while the mean shape indices (sphericity, elongation index and flatness index) increase in a logarithmic-linear form, with increasing strain rates. In addition, the fragment size and shape distributions are all found to follow the Weibull probability distribution. To reveal the underlying mechanisms of such strain rate effects, high-speed optical and X-ray imaging are implemented to capture the fracture process of ceramic samples under quasi-static and dynamic compression. Primary and secondary wing cracks (PWCs/SWCs) control the fracture and fragmentation of the ceramic under both loading conditions. Compared to quasi-static loading, a considerably larger number of SWCs are produced under dynamic loading, and pronounced branching and bridging occur among the PWCs, which prevent the PWCs from coalescing into axial splitting cracks. Consequently, crack networks composed of high-density wing cracks break the sample into finer and more isotropic fragments, consistent with CT characterizations. Scanning electron microscopy is utilized to analyze the micro damage modes of ceramic samples. Transgranular fracture dominates the grain-scale damage and contributes to the higher dynamic fracture resistance of the alumina under dynamic loading, as a result of more homogeneous nucleation and growth of micro cracks.

Creep Deformation and Rupture Life Characteristics of High-Purity Aluminum for High-Power Electronic Devices

Creep Deformation and Rupture Life Characteristics of High-Purity Aluminum for High-Power Electronic Devices

Technologia reaktywnego rozpylania magnetronowego do otrzymywania azotków III

In the present work is studied synthesis of galium nitride (GaN) and aluminum nitride (AlN) by DC Reactive Magnetron Sputtering technology. As a sputtering target was used high purity (99.9999%) Gallium and Aluminum materials and as a reagent gas was used high purity (99.9999%) Nitrogen. Magnetron sputtering system with strong magnets (1450 mT) allows to make plasma at a low preasure 3 × 10-2 Pa and deposition process was carried out at high vacuum conditions. Deposited layers of GaN and AlN on the sappire substrate was analysed by X-ray diffraction (XRD) and revealed the crystalline nature highly oriented with the (0002) for both nitrides. For chemical composition was measured X-ray Photoelectron Spectroscopy (XPS) and it was found out the ratios of Ga:N and Al:N to be 1.07 and 1.04 respectively. For surface analysis was made Scanning Electron Microscopy (SEM). Optic transmission spectra showed band gaps to be 3.43 eV and 6.13 eV for GaN and AlN respectively.

Mechanism study of synergistic aluminum extraction and purification by ammonium for high-value conversion of secondary aluminum dross

Secondary aluminum dross (SAD) constitutes a significant volume of hazardous solid waste with huge productions. Balancing extraction efficiency and purity within the current resourcing recovery process proves challenging and impedes high-value conversion. Consequently, the NH4HSO4-H2SO4 system was employed in this study to convert SAD into high-purity alumina nanoparticles, and the effect of ammonium was investigated. The results indicated that the leaching rate reached 85.98 % under the optimum conditions (170 °C, [Htot]=12 mol/L, 16/1,6 h); the interaction of NH4+ and H+ with the oxygen atoms on the surface of Al2O3 was demonstrated to enhance the reactivity of the aluminum atoms by DFT calculations. The incorporation of NH4+ also facilitated the separation of aluminum by leveraging the temperature-dependent solubility characteristic of NH4Al(SO4)2. Molecular dynamics simulation revealed that NH4+ inhibits the diffusion rate of Al3+, thereby regulating the doping impurities such as Mg and Ca, and improving the purity of Al2O3 (95.29–99.64 %). Additionally, Nanoscale regulation was executed through the conversion of the NH4AlO(OH)HCO3 precursor and control. The sintering and agglomeration problems brought about by pyrolysis in atmospheres such as H2O and SO3 were avoided. This research provides reference for the high-value utilization of aluminum-containing solid waste.

Identification and seasonal variation of specific particulate bound (halogenated) polycyclic aromatic hydrocarbons in air from different metal industrial parks in Northwest China.

During the process of industrial heating, a large amount of polycyclic aromatic hydrocarbons (PAHs) and their halogenated compounds (Cl/Br-PAHs) can be formed. However, there is still limited understanding of the chemicals from different metal smelting industrial parks. This study evaluated the seasonal variations, composition profiles, and source allocations of the atmospheric particulate-bound PAHs and Cl/Br-PAHs in different metal industrial parks in a typical industrial city in northwest China. The results showed that the main PAHs produced by metal smelting were low molecular weight isomers, and the concentrations of Cl-PAHs were lower compared to Br-PAHs. The main Br-PAHs were 1-Br-Pyr and 4-Br-Pyr, while 9-Cl-Fle, 1-Cl-Pyr, and 6-Cl-BaP were the dominated Cl-PAH isomers. No significant difference was found in the concentrations among the sites, whereas the levels of the target chemicals were higher during cold months compared to warm months. The main source of PAHs was coal combustion and gasoline vehicle emission during metal smelting, and that of Cl/Br-PAHs was also industrial coal burning. In addition to the primary source, the secondary chlorination of parent PAHs was also a significant source of Cl-PAHs in the production of high purity aluminum. This study suggests that Cl-PAHs and Br-PAHs may behave differently in the atmosphere.

High efficiency solar-grade silicon producing by directional solidification through controlling diffusion of impurity

The precise distribution of impurity of the whole silicon ingot is investigated through a theoretical model and the experiments. This model solves the problem of inaccurate prediction of impurity distribution in the final solidification region. The model was used to calculate the distribution of iron impurity in polycrystalline silicon ingots after directional solidification and compared with experiments. The calculation accuracy was significantly improved compared to the traditional Scheil equation. This paper investigates the influence of cooling rate, silicon ingot height and solidification rate on the yield of purified products after directional solidification. For the experimental equipment and raw materials in this paper, the optimal cooling rate of silicon ingots after directional solidification is 0.33 °C/s, the optimal height of silicon ingots is 0.34 m, and the yield of silicon purification increases with the decrease of directional solidification rate. Based on the research results, a standard for removing the top skin of silicon ingots after directional solidification and a method for improving the purification yield by suppressing impurity diffusion during the cooling stage were obtained. This model can provide theoretical guidance for the development of low-cost and high-efficiency methods for removing impurities from polycrystalline silicon, and is of great significance for the development of the photovoltaic industry. In addition, the theoretical model proposed in this paper can also be applied to the directional solidification purification process of other materials, such as the preparation of high-purity aluminum and high-purity titanium, and can predict the impurity migration behavior and distribution pattern throughout the purification process.

Ab initio molecular dynamics study on the local structures and solid/liquid interface in liquid Al-Ti and Al-B-Ti alloys

High-purity aluminum, owing to its excellent physical and chemical properties, finds extensive applications across various fields. A comprehensive understanding of the local structure of liquid Al-based alloys and the characteristics of solute atoms at the forefront of the solid-liquid interface is highly advantageous for the purification of aluminum. Ab initio molecular dynamics (AIMD) simulations were employed to study the local structures, element interactions and electronic structures in Al-Ti and Al-B-Ti melts, together with the behaviors of Ti atom and B-Ti atom pair at the solid/liquid interface forefront of Al. In the Al-B-Ti ternary melt, there are stronger interactions between B and Ti atoms than those between Al and B atoms as well as between Al and Ti atoms. The introduction of B atoms leads to the disruption of Al-Ti bonds and the formation of B-Ti bonds, thereby altering the state of Ti atoms in the melt and then influencing their diffusion properties. The dynamic process of B-Ti bond formation in the melt has been elucidated. The bond angle distribution function shows that the geometric configuration around Ti atoms in the Al melt undergoes significant changes with the addition of B atoms. A strong hybridization occurs between the 3d orbital of Ti atom and the 2p orbital of B atom. Moreover, a notable charge accumulation between B and Ti atoms, indicates the strong interaction between them. The addition of Ti atom can promote the migration of the Al solid/liquid interface. The B-Ti bond is very stable at the forefront of the Al solid/liquid interface, and the formation of B-Ti bond significantly drag the migration of the Al solid/liquid interface.

Study on influence of microalloying of high purity aluminum with scandium and zirconium on physical and mechanical properties of capacitor foil

Study on influence of microalloying of high purity aluminum with scandium and zirconium on physical and mechanical properties of capacitor foil

Study on Preparation Technology and Heat Conduction Mechanism of High-Purity & Ultra-Fine Alumina Powder from Scrap Aluminum Cans

In view of the increasing scarcity of bauxite resources in China, the high energy consumption and high pollution of electrolytic aluminum, and the requirements for energy conservation and environmental protection, aluminum recycling and high-value utilization of its derivatives have evolved into a crucial development requirement for the aluminum industry in the future. As an important part of the development of recycled aluminum resources, the high-value application of scrap aluminum cans has always been a hot research topic in various recycled aluminum processing enterprises and scientific research units. The traditional regeneration system of waste cans includes a series of complex technological processes such as pretreatment, paint removal, smelting system and casting system, which is difficult to control in the middle of the process. Most of the recycled scrap aluminum cans are cast and downgraded for later use, except for a part of them used as alloy materials for new cans. In this paper, combined with the research on the preparation of metal aluminum alkoxide, combined with recrystallization heat conduction to further study the effective dissolution or adsorption how to remove impurity elements to obtain high-purity aluminum alcohol salt mechanism research, and thermal effect of alcohols with different carbon chains on the synthesis of high-purity aluminum alkoxide was further investigated. Moreover, the changes in morphology and pore size distribution of hydrolyzed alumina precursor materials under different hydrothermal temperature conditions were discussed by means of the alkoxide hydrolysis-sol-gel process. Eventually, the aluminum alkoxide was obtained by the reaction of waste cans with isopropanol and heavy crystal thermal conductivity, and the high-purity aluminum alkoxide was purified by vacuum distillation. Under the hydrothermal condition of 160°C, the high-purity alumina material with a purity of 99.99% and an original crystal size of 200nm was prepared.