Industrial Aluminum Research Articles

Effect of spent alumina catalyst and date palm fiber ash addition in the development of aluminum based composite

This study focuses on utilizing waste aluminum as a base material and aims to fabricate a new green composite material by incorporating industrial aluminum waste, carbonized date palm fiber (CDPF), and spent alumina catalyst (SAC) powder as reinforcing agents. Initially, this type of waste disposal SAC, along with date palm fiber ash, has not been used before. In practical applications, we can utilize our composite in the automobile industry since the results show improved mechanical properties and reduced corrosion. By introducing 1.25% SAC and 6.25% carbonized palm fiber (CDPF) particles into the waste aluminum, significant improvements have been observed in mechanical characteristics like tensile strength, hardness, and toughness. Comparative analysis with the base material reveals enhancements of approximately 20.82%, 33.11%, and 22.72% in tensile strength, hardness, and toughness, respectively. Moreover, a reduction in composite elasticity has been observed. The SEM and EDX results demonstrate a uniform microstructure in the composite material. Corrosion experiments indicate that the addition of SAC and CDPF effectively minimizes the annual corrosion rate.

Efficient rhodamine B dye degradation by red mud-grapefruit peel biochar catalysts activated persulfate in water.

The continuous and rapid development of textile industry intensifies rhodamine B dye (RhB) wastewater pollution. Meanwhile, massive red mud (RM) solid waste generated by the industrial alumina production process poses detrimental effects to the environment after leaching. For resource utilization and to reduce the expansion of RhB pollution, RM and peel red mud-biochar composite (RMBC) catalyst were synthesized in activating peroxydisulfate (PDS) for RhB degradation. Firstly, characterization results showed that compared to RM, RMBC had a higher content of catalytically active metals (Fe, Al, Ti) (higher than 0.92-4.18%), smaller pore size, and larger specific surface area (10 times), which verified RMBC had more potential catalytic oxidation activity. Secondly, under optimal dosage (catalyst, PDS), pH 4.6, and 20 mg L-1 RhB, it was found that the RhB degradation ratio of RM was 76.70%, which was reduced to 41% after three cycles, while that of RMBC was 89.98% and 67%, respectively. The results indicated that the performance of RMBC was significantly superior to that of RM. Furthermore, the quenching experiments, electron paramagnetic resonance spectroscopy tests, FTIR, and XPS analysis showed the function of O-H, C=O, C-O, Fe-O, and Fe-OH functional groups, which converted the PDS to the active state and hydrolyzed it to produce free radicals ([Formula: see text], 1O2, [Formula: see text]) for RhB degradation. And, Q Exactive Plus MS test obtained that RhB was degraded to CO2, H2O, and intermediate products. This study aimed to raise a new insight to the resource utilization of RM and the control of dye pollution.

An experimental investigation of high-temperature thermochemical conversion of oil shale residues into valuable materials

Oil shale residues, a solid waste produced during oil shale mining, extraction, and refining processes, pose a significant challenge to the environment and sustainability. This study aims to develop a thermochemical conversion process to transform oil shale residues into valuable composite materials. Experiments are conducted to investigate the effects of reaction temperature, time, and reactant composition on the reaction behavior and resulting product characteristics. The results demonstrate that mullite-rich composite materials can be prepared at reaction temperatures of around 1300 °C with reaction times of 5 min. Industrial aluminum ash can be used to supplement the aluminum needed for the complete conversion of excess SiO2 in oil shale residue, but it must be thermally treated to eliminate the NaCl content, which hinders mullite formation. Overall, this study offers a viable approach to converting solid waste into valuable resources while simultaneously addressing the environmental concerns associated with oil shale residues.

A Federated Dictionary Learning Method for Process Monitoring With Industrial Applications

Edge computing is an indispensable technology in the Industry 4.0 era. Data is stored at the edge and transmission is prohibited due to concerns about data privacy. Thus, the traditional centralized data-driven modeling methods will face many difficulties and can hardly be used in practice. Federated learning aims to let local nodes learn a global model cooperatively while keeping their data localized. Motivated by the pioneering framework of federated learning, a federated dictionary learning method is proposed for process monitoring. In detail, local nodes train local data by K-SVD method and learn local dictionaries. Then, local dictionaries, instead of local data, are transferred to the fusion center for calculation of the global dictionary. In order to guarantee an optimal global dictionary, a novel federated dictionary average strategy is introduced. Finally, the reconstruction errors of local data and the control limit are calculated based on the global dictionary for process monitoring. The performance of the proposed method is verified on a numerical simulation, the CSTH benchmark process, and the industrial aluminum electrolysis process.

Hydrogen from industrial aluminium scraps: Hydrolysis under various conditions, modelling of pH behaviour and analysis of reaction by-product

The study explores the feasibility of utilizing aluminium scrap waste from the construction industry for hydrogen production via hydrolysis. Specifically, the study involves a primary analysis of aluminium scrap waste and the impact of various reaction parameters, such as NaOH molarity, reaction temperature, amount of Al scrap, solvent quantity, and the reaction vessel insulation, and their effects on the reaction rate, H2 yield, and by-product formation. The pH of the reaction solution was continuously monitored to determine the reaction mechanism, while the structure of the by-product was analysed at two stages: after removal and drying, and after removal and washing. Our findings indicate that increasing the reaction temperature has the most significant influence on the reaction kinetics. Insulating the reaction vessel ensured self-promoted hydrogen production due to the heat generated from the exothermic reaction inside the vessel, resulting in an approximate temperature increase of 5 °C for all tested reaction solution molarities compared to non-insulated conditions. The pH measurements were conducted in two different ways. The first one involved immersing a pH probe directly into an open reaction container. The second approach utilized a closed reaction container under isothermal conditions, where both the pH and H2 yield were measured simultaneously. In addition, the obtained data was compared between the measured pH values and the predictions generated by models utilizing the measured H2 evolution in order to forecast the pH behaviour. The modelling results recognize and suggest the existence of separate reaction phases or zones, each characterized by distinct influences on the pH level.

Micro-CT in the mechanical properties and energy absorption of closed-cell aluminium foam

In situ loading experiments of closed-cell aluminium foam with densities of 0.217 g/cm3, 0.347 g/cm3, 0.414 g/cm3 and 0.588 g/cm3 prepared from industrial pure aluminium 1060 and titanium hydroxide TiH2 foaming agent were carried out by micro-CT. The pore structure parameters such as porosity, pore size distribution and sphericity of aluminium foams with different densities were analyzed, and the effects of pore structure parameters on mechanical properties and energy absorption were investigated to reveal the differences in mechanical characterization of aluminium foams with different densities. The results show that: the collapse of aluminium foam pores in the in-situ loading experiments starts from the high porosity region; aluminium foam with high density has low porosity, small pores and good sphericity; the stress-strain curve of aluminium foam with high density is located above and the elastic modulus is large; the energy absorption capacity is related to the density of aluminium foam, and the energy absorption capacity is large with high density, but the energy absorption efficiency is mainly related to whether the structure is uniform or not.

A dynamic spatial distributed information clustering method for aluminum electrolysis cell

Distributed anode current (DAC) is a high-dimensional spatial-distributed signal that can be measured online in the industrial aluminum electrolysis process. The difference of physicochemical properties in different spatial regions in an aluminum electrolysis cell can be obtained by spatial clustering analysis of DAC data. In this study, a dynamic spatial distributed information clustering method (DSDIC) for aluminum electrolysis cell is proposed. This method can effectively capture the complex dynamic spatio-temporal correlations in DAC. Firstly, the dynamic graph is identified to capture the complex dynamicity of the DAC. Then, the anode-spatial structure information (ASSI) extends the one-dimensional current signal generated by each carbon anode into a feature matrix to achieve the fusion of data and spatial structure knowledge. Finally, the adjacency matrix of dynamic graph performs low-pass filtering on the feature matrix to obtain low-frequency information that is beneficial to downstream learning tasks. Meanwhile, a fixed graph structure based on process mechanism knowledge is designed to capture the spatial correlation caused by external periodic operations in industrial process. The experimental results on the actual industrial aluminum electrolysis datasets show that our method improves the clustering accuracy by 3.96% compared with existing clustering methods.

Comparison of microstructure and mechanical properties of industrial pure aluminum produced by powder metallurgy and conventional rolling

Aluminum alloys are produced by different manufacturing techniques and each technique produces a unique microstructure. One of the most versatile manufacturing methods is powder metallurgy (P/M) because it produces a final fine or ultrafine grain microstructure. But it requires powder consolidation and densification processes after P/M. In the other side, Hot Isostatic Pressing (HIP) is now recognized as a very interesting technique to densify advanced materials with a high potential. The aims of this work are: to produce an AA1100 aluminum billet by powder densification followed by HIP and to compare its microstructure and mechanical properties against the ones of an AA1100 aluminum plate produced by conventional rolling. The mechanical properties were measured using tensile test and Charpy test. The results show that the tensile strength of the P/M+HIP sample is higher than the one of the aluminum plate, but the yield strengths are similar. In the other hand the impact toughness results are very different from each other.

Effect of (5%) CO2 on the Oxidation Rate During Cooling of Industrial Aluminum White Dross

Aluminum (Al) white dross is classified as hazardous waste and originates from the primary production of Al as a result of molten metal oxidation at an industrial scale. As the produced dross reduces the annual metallic Al production by up to 10%, finding a way to reduce the dross formation has always been of interest. Several laboratory studies have shown that exposing molten Al to small amounts of CO2 has an inhibiting effect on the oxidation rate of the metal. Still, few studies have described this effect at an industrial scale. The present work has therefore studied the impact of protective cooling of industrial white dross samples on the oxidation rate of the dross to shed some light on the issue. Samples were collected from the holding furnace in a casthouse during the production of two different charges of Al alloys with varying amounts of magnesium (Mg), i.e., Charge 1 (AlMg1.0Mn0.4) and Charge 2 (AlMg1.2Mn0.4). The samples were cooled in ambient air and under a lid with 5% CO2 mixed with 95% synthetic air in two parallels and later characterized by X-Ray Diffraction and Electron Probe MicroAnalysis combined with deterministic image analysis. Both methods confirm that all samples cooled under the protective atmosphere with 5% CO2 had a higher content of metallic Al (89.4 wt%) than those cooled in ambient air (86.0 wt%), indicating that small amounts of CO2 also inhibit the oxidation rate of dross at an industrial scale.Graphical

Cooling channel free surface optimisation for additively manufactured casting tools

In the present study, an algorithm has been developed using the adjoint method to optimise the position and cross-section of an internal cooling channel for a 3D printed tool steel insert for use in the aluminium die-casting process. The algorithm enables the development of an optimised complex industrial mould with relatively low computational cost. A transient model is validated against multiple experimental trials, providing an adapted interface heat transfer coefficient. A steady state thermal model, based on the casting cycle and thermal behaviour at the mould surface, is developed to evaluate the spatial distribution of temperature and to serve as the initial solution for the subsequent optimisation stage. The adjoint model is then applied to optimise the cooling channel emphasising the minimisation of the temperature standard deviation for the mould surface. The original transient model is applied to the optimised mould configuration via calibration using experimental data obtained from a dedicated aluminium furnace. The optimised cooling channel geometry, which uses a non-uniform cross-section across the entire pipe surface region, improves the pressure drop and cooling uniformity across the mould/cast interface by 24.2% and 31.6%, respectively. The model has been used to optimise cooling channels for a range of industrial high-pressure aluminium die-casting (HPADC) inserts. This has yielded a significant improvement in the mould operational lifetime, rising to almost 130,000 shots compared to 40,000 shots for prior designs.

On the Competition between Intergranular and Transgranular Failure within 7xxx Al Alloys with Tailored Microstructures.

7xxx aluminium series reach exceptional strength compared to other industrial aluminium alloys. However, 7xxx aluminium series usually exhibit Precipitate-Free Zones (PFZs) along grain boundaries, which favour intergranular fracture and low ductility. In this study, the competition between intergranular and transgranular fracture is experimentally investigated in the 7075 Al alloy. This is of critical importance since it directly affects the formability and crashworthiness of thin Al sheets. Using Friction Stir Processing (FSP), microstructures with similar hardening precipitates and PFZs, but with very different grain structures and intermetallic (IM) particle size distribution, were generated and studied. Experimental results showed that the effect of microstructure on the failure mode was significantly different for tensile ductility compared to bending formability. While the tensile ductility was significantly improved for the microstructure with equiaxed grains and smaller IM particles (compared to elongated grains and larger particles), the opposite trend was observed in terms of formability.

Adsorption performance and mechanism of mesoporous carbon-doped Al2O3 adsorbent derived from NH2-MIL-53 (Al) for removing Cr(Ⅵ) and methyl orange from aqueous solution

A new porous carbon-doped Al2O3 adsorption material was prepared by calcination at 600 °C with the use of aluminum-based metal–organic framework synthesized by hydrothermal method with aluminum as the metal source to solve the problem of instability of MIL-53 in aqueous solution. It was used to remove methyl orange (MO) from single system and aqueous solution with Cr(Ⅵ). The microstructure of the material was characterized by modern analytical techniques, and its adsorption capacity and mechanism were explored. PXRD, SEM, BET and other characterization methods show successfully synthesized NH2-MIL-53(Al) with porous carbon-doped Al2O3 structure. The precursor NH2-MIL-53(Al) and the calcined derivative porous carbon-doped Al2O3 are similar in morphology, and the specific surface area of porous carbon-doped Al2O3 (180.24 m2/g) is larger than that of NH2-MIL-53(Al) (116.73 m2/g). The maximum equilibrium adsorption capacity of Cr(Ⅵ) and MO by porous carbon-doped Al2O3 material could reach 671.56 and 612.09 mg/g, respectively. The fitting results of the adsorption kinetic model show that the adsorption behavior of porous carbon-doped Al2O3 material for Cr(Ⅵ) is more suitable to Langmuir isotherm model, whereas that of MO is more suitable to Freundlich isotherm model. Both are suitable to pseudo-second-order kinetic model. According to XPS analysis, the contents of Cr(III) and Cr(VI) calculated by C600-6 after adsorption are 56.1 % and 44.9 %, indicating that electrostatic interaction and redox action still play a leading role in the adsorption of Cr(VI), while electrostatic interaction and chelation play a leading role in the adsorption of MO. Studies show that the porous carbon-doped Al2O3 material could be used as a Cr(Ⅵ) and MO removal material to achieve efficient removal of Cr(Ⅵ) and MO. The alumina synthesized by MOF is more stable than the traditional industrial alumina, and its acid and alkaline resistance is more excellent. This material not only solves the problem of instability and uneven distribution of MIL-53 crystal and common alumina materials but also provides more adsorption sites.

Integrated fatigue life predictions of aluminium castings using simulated local microstructure and defects

In this work, an integrated simulation approach previously developed for static FE analyses is extended to microstructure- and defect-based fatigue life assessments of castings. The approach, the closed chain of simulations for cast components, combines casting process simulation with microstructure modelling and local material characterisation to generate heterogeneous material data for FE analysis and fatigue life assessment. The method is demonstrated on a High-Pressure Die Cast aluminium component. Areas with a high risk of defects are identified based on the simulated solidification conditions, and heterogeneous material data for the fatigue life analysis is generated. Fatigue testing has been performed with different levels of porosities to quantify the effect of defects on the element-specific Wöhler curves. Pore characteristics are assessed using 2D X-ray, fracture surface analysis and Kitagawa diagram. The results highlight the importance of taking the risk of defect formation into consideration when designing industrial aluminium castings subjected to fatigue loads.

Undissolved alumina in dynamic chunks piercing through the bath - metal interface in industrial aluminum electrolysis cells

In Hall–Héroult cells the uninvolved alumina precipitates on the top of the cathode to form resistive deposits which could significantly impact the energy consumption. A dynamic energy conservation (DEC) approach has been developed to quantify the flux of undissolved alumina piercing the interface between the electrolyte and the liquid metal inHall–Héroultcells. The proposed DEC model considers both electrochemical and interfacial phenomenon between the electrolyte and the liquid metal. A critical radius at or below which a particle of undissolved alumina is retained at the electrolyte/liquid metal pad interface is defined and quantified considering the heat transfer and electrolysis cell operating parameters: temperature, electrolyte composition, alumina porosity, and current density. The proposed approach appears reliable to quantify the amount of undissolved alumina which pierces the electrolyte/liquid metal pad interface and precipitates to the bottom of the cell to form a deposit on the cathode.

Effect of the in-situ SiC whiskers on the alkali attack resistance mechanism of mullite-SiC foam ceramics

In this study, five mullite foamed ceramics were prepared with industrial alumina, white clay, and varying Si powder contents. The effect of the in-situ SiC whisker generation content controlled by the varying Si powder contents on the compressive strength, alkali attack resistance, and thermal conductivity of the ceramics was investigated and the optimal SiC whisker generation content was confirmed. With a rise in Si powder content, the porosity of the foamed ceramics decreased, the thermal conductivity increased, and the compressive strength increased first and then decreased. The alkali corrosion resistance improved by decreasing the diffusion rate of alkali vapor and improving the stability of ceramic matrices. Taking mechanical properties, thermal insulating properties, and alkali attack resistance into consideration, the optimized product was a specimen with 10 wt% Si powder content.

MORPHOLOGICAL CHARACTERISTICS OF CRATERS ON THE SURFACE OF AA1933 ALUMINUM ALLOY IRRADIATED BY PULSED ELECTRON BEAM

Irradiation of an industrial aluminum alloy AA1933 with an intense pulsed electron beam with particle energy of 0.35 MeV, a beam current of 2.0 kA, a pulse duration of 5 μs, and a beam diameter of 3 cm results in the formation of a surface layer with a modified structural-phase state. A characteristic feature of the irradiated surface is the presence of cracks and craters on it. This study features the types and morphology of craters on the surface of aluminum alloy AA1933 formed as a result of irradiation by a pulsed electron beam. The study includes figures of a variety of crater types. The distribution of craters according to size and crater density on the irradiated surface was examined. The study also provides for the discussion of the significance of these observations for the sake of a better understanding of the mechanisms of crater formation during irradiation by pulsed electron beams.

Joint process of laser shock polishing and imprinting for metallic nanostructure fabrication

Most fabrication methods of metallic nanostructures are time-consuming with multi-steps, which are difficult to achieve low-cost batch processing. In this study, joint laser process of laser shock polishing & imprinting (LSPI) is proposed to efficiently fabricate large-area nanostructures on the surface of cheap industrial aluminum foil without any pre-processing step. LSPI tailors the laser parameters of single laser manufacturing equipment to apply laser shock polishing (LSP) to polish the aluminum foil, and then laser shock imprinting (LSI) to obtain nanostructures with high accuracy, integrity and uniformity. This unique characteristic of proposed LSPI is enabled by pre-taking LSP process to improve the yield of following LSI process through significantly decreasing the surface roughness of aluminum foil. LSPI also reduces the aluminum residue inside the silicon mold, which improves the integrity of resultant nanostructure and facilitates the reuse of the mold. The working mechanism of LSPI are also investigated to reveal its fundamental fabrication principle, which may inspire other low-cost and efficient batch fabrication method for metallic nanostructures manufacturing in the future.

Characterization of Zr-Containing Dispersoids in Al-Zn-Mg-Cu Alloys by Small-Angle Scattering.

The characterization of Zr-containing dispersoids in aluminum alloys is challenging due to their broad size distribution, low volume fraction, and heterogeneous distribution within the grains. In this work, small-angle X-ray scattering (SAXS) and small-angle neutron scattering (SANS) were compared to scanning electron microscopy (SEM) and transmission electron microscopy (TEM) regarding their capability to characterize Zr-containing dispersoids in aluminum alloys. It was demonstrated that both scattering techniques are suitable tools to characterize dispersoids in a multi-phase industrial 7xxx series aluminum alloy. While SAXS is more sensitive than SANS due to the high electron density of Zr-containing dispersoids, SANS has the advantage of being able to probe a much larger sample volume. The combination of both scattering techniques allows for the verification that the contribution from dispersoids can be separated from that of other precipitate phases such as the S-phase or GP-zones. The size distributions obtained from SAXS, SANS and TEM showed good agreement. The SEM-derived size distributions were, however, found to significantly deviate from those of the other techniques, which can be explained by considering the resolution-limited restrictions of the different techniques.

A composite strategy for high-quality and high-efficiency milling of alumina ceramic via femtosecond laser burst-mode

Industrial alumina ceramics require high surface accuracy when assembled to critical components of devices, for which high-quality milling has become an integral process. To achieve high-quality milling of alumina ceramics efficiently, this paper introduced a composite strategy based on the sequence of roughing and finishing via the femtosecond laser burst-mode. Firstly, the effects of laser parameters in the single-pulse mode such as energy fluence, spot overlap ratio, and scanning spacing on the milling quality and efficiency of alumina ceramics were investigated to provide a basis of the parameter selection for the subsequent composite strategy study. Then, the influence of the burst-mode on the optimization of the milling results was discussed, and the advantages of this mode over the single-pulse mode were revealed. Finally, a comparative investigation on the processing performance between the composite strategy and the single strategy was carried out. The results showed that milling the same structure, the roughness of the groove was reduced by 10.69% compared to the optimal processing results in a single process. At the same time, the processing efficiency was maximized with an increase of 49.91%.

Disordered interfaces of alkaline aluminate salt hydrates provide glimpses of Al3+ coordination changes

HypothesisThe precipitation and dissolution of aluminum-bearing mineral phases in aqueous systems often proceed via changes in both aluminum coordination number and connectivity, complicating molecular-scale interpretation of the transformation mechanism. Here, the thermally induced transformation of crystalline sodium aluminum salt hydrate, a phase comprised of monomeric octahedrally coordinated aluminate which is of relevance to industrial aluminum processing, has been studied. Because intermediate aluminum coordination states during melting have not previously been detected, it is hypothesized that the transition to lower coordinated aluminum ions occurs within ahighly disordered quasi-two-dimensional phase at the solid-solution interface. Experiments and simulationsIn situ X-ray diffraction (XRD), Raman and27Al nuclear magnetic resonance (NMR) spectroscopy were used to monitor the melting transition of nonasodium aluminate hydrate (NSA, Na9[Al(OH)6]2·3(OH)·6H2O). A mechanistic interpretation was developed based on complementary classical molecular dynamics (CMD) simulations including enhanced sampling. A reactive forcefield was developed to bridge speciation in the solution and in the solid phase. FindingsIn contrast to classical dissolution, aluminum coordination change proceeds through a dynamically stabilized ensemble of intermediate states in a disordered layer at the solid-solution interface. In both melting and dissolution of NSA, octahedral, monomeric aluminum transition through an intermediate of pentahedral coordination. The intermediate dehydroxylates to form tetrahedral aluminate (Al(OH)4−) in the liquid phase. This coordination change is concomitant with a breaking of the ionic aluminate-sodium ionlinkages. The solution phase Al(OH)4− ions subsequently polymerize into polynuclear aluminate ions. However, there are some differences between bulk melting and interfacial dissolution, with the onset of the surface-controlled process occurring at a lower temperature (∼30 °C) and the coordination change taking place more gradually as a function of temperature. This work to determine the local structure and dynamics of aluminum in the disordered layer provides a new basis to understand mechanisms controlling aluminum phase transformations in highly alkaline solutions.