Pure Aluminum Research Articles

Influence of Inoculation and Texture on Enhancing Electrical Conductivity in Commercially Pure Aluminum for Squirrel-Cage Asynchronous Electrical Motors

Influence of Inoculation and Texture on Enhancing Electrical Conductivity in Commercially Pure Aluminum for Squirrel-Cage Asynchronous Electrical Motors

Al(SO4)(OH)·5H2O Stemming from Complexation of Aluminum Sulfate with Water-Soluble Ternary Copolymer and further Stabilized by Silica Gel as Effective Admixtures for Enhanced Mortar Cementing.

A water-soluble ternary copolymer bearing carboxyl, sulfonic, and amide functional groups was synthesized using ammonium persulfate-catalyzed free radical polymerization in water, resulting in high monomer conversion. This copolymer was then complexed with aluminum sulfate, forming an admixture containing Al(SO4)(OH)·5H2O, which was subsequently combined with silica gel. Characterization revealed that the synthesized copolymer formed a large, thin membrane that covered both the aluminum compounds and the silica gel blocks. The introduction of this complex admixture, combining the copolymer and aluminum sulfate, not only reduced the setting times of the cement paste but also enhanced the mechanical strengths of the mortar compared to using aluminum sulfate alone. The complex admixture led to the formation of katoite, metajennite, and C3A (tricalcium aluminate) in the mortar, demonstrating significant linking effects, whereas pure aluminum sulfate could not completely transform C3S within 24 h. Further addition of silica gel to the complex admixture further shortened the setting times of the paste, slightly reduced compressive strength, but improved flexural strength compared to the initial complex admixture. The silicon components appeared to fill the micropores and mesopores of the mortar, accelerating cement setting and enhancing flexural strength, while slightly decreasing compressive strength. This study contributed to the development of new cementing accelerators with improved hardening properties.

A fast and efficient Al-5Ti-1B grain refiner prepared by gas-assisted continuous casting and extrusion process

The feasibility of preparing Al-Ti-B alloy wires based on a novel technology of gas-assisted continuous casting and extrusion (GAC) was investigated. Results show that Al-5Ti-1B alloy wire with fine and uniform distribution of the second phase can be prepared by combining the fluoride salt method and the GAC process. When the wire was added into an industrial pure aluminum at 730 °C with an addition of 0.2 wt%, the pure aluminum grains could be refined into equiaxed crystals with an average size of about 140 μm by contacting time of 60 s, which showed the characteristics of rapidity and high efficiency.

Investigation of Al-Li particle ignition dynamics with different Li content

Promoting the ignition of aluminum powder is considered an effective method to inhibit the agglomeration of aluminum powder in propellants and enhance combustion efficiency. This study utilizes laser ignition technology and high-speed photography to investigate the ignition and combustion processes of single aluminum particles and aluminum-lithium alloy particles. The focus is on comparing the effects of the diameter of micron-sized metal particles and the lithium content in aluminum-lithium alloy particles on the ignition and combustion processes of metal particles. The results show that the ignition delay time is directly proportional to the diameter of the metal particles and inversely proportional to the lithium content. For the aluminum-lithium alloy particle with a lithium content of 3.5 %, even if the diameter is close to 300 μm, the ignition delay time is only 125.5 ms, which is much smaller than that of the pure aluminum particle with a diameter of 208 μm. Compared to aluminum particles and aluminum-lithium alloy particles, there is basically no difference between the two during the combustion stage. However, in the ignition stage, aluminum-lithium alloy particles sequentially exhibit a red gas-phase flame corresponding to lithium and a yellow gas-phase flame corresponding to aluminum. This indicates that during the ignition process of aluminum-lithium alloy particles, lithium first reacts with the oxidative atmosphere and releases heat, providing a heat source for the subsequent ignition of aluminum particles. This also explains why the ignition delay time of metal particles is inversely proportional to the lithium content. An ignition model for aluminum particles in a multi-component atmosphere is established, which further considers the chemical reactions between lithium and oxidative gases, making the model applicable to aluminum-lithium alloy particles. This ignition model effectively describes the impact of particle diameter and lithium content on the ignition process of metal particles. The model is further verified, and the results show that the calculated ignition delay is in good agreement with the experimental data. Overall, this study provides deeper experimental and theoretical insights into the ignition and combustion processes of aluminum-lithium alloys, and the findings can guide the application of aluminum-lithium alloys in propellants.

Enhancing Mechanical Properties of Graphene/Aluminum Nanocomposites via Microstructure Design Using Molecular Dynamics Simulations.

This study explores the mechanical properties of graphene/aluminum (Gr/Al) nanocomposites through nanoindentation testing performed via molecular dynamics simulations in a large-scale atomic/molecular massively parallel simulator (LAMMPS). The simulation model was initially subjected to energy minimization at 300 K, followed by relaxation for 50 ps under the NPT ensemble, wherein the number of atoms (N), simulation temperature (T), and pressure (P) were conserved. After the model was fully relaxed, loading and unloading simulations were performed. This study focused on the effects of the Gr arrangement with a brick-and-mortar structure and incorporation of high-entropy alloy (HEA) coatings on mechanical properties. The findings revealed that Gr sheets (GSs) significantly impeded dislocation propagation, preventing the dislocation network from penetrating the Gr layer within the plastic zone. However, interactions between dislocations and GSs in the Gr/Al nanocomposites resulted in reduced hardness compared with that of pure aluminum. After modifying the arrangement of GSs and introducing HEA (FeNiCrCoAl) coatings, the elastic modulus and hardness of the Gr/Al nanocomposites were 83 and 9.5 GPa, respectively, representing increases of 21.5% and 17.3% compared with those of pure aluminum. This study demonstrates that vertically oriented GSs in combination with HEA coatings at a mass fraction of 3.4% significantly enhance the mechanical properties of the Gr/Al nanocomposites.

Effect of heat treatment before fast multiple rotation rolling on friction surfaced Al–Si–Cu alloy

In this study the effect of combination of heat treatment of consumable rod and solid solution heat treatment before fast multiple rotation rolling (FMRR) processing on microstructure, mechanical property and wear resistance of Al–Si–Cu alloy friction surfaced on commercial pure aluminum alloy were investigated. Results show that after the FMRR process, there is a significant reduction (99% reduction) in the friction surfaced coating surface roughness. The surface roughness after FMRR processing in the coatings created by homogenized and solid solution treated consumable rod is 0.74 ± 0.12, and 0.56 ± 0.08 μm, respectively. In the coating created by homogenized rod the minimum grain size (1.7 ± 0.2 μm) formed in the FMRR processed layer. Using homogenized consumable rod and FMRR processing by rotational speed of 3000 rpm and traverse speed of 140 mm/min, the maximum hardness (9.8 ± 0.3 GPa) and minimum wear rate (4.6 ± 0.1 μg/m) created at processed layer. FMRR processing by rotational speed of 3000 rpm and traverse speed of 140 mm/min, result in 27 and 24 % increasing in hardness at friction surfaced coating created by homogenized and solid solution treated consumable rods, respectively.

Integrating machine learning and parametric design for energy-efficient building cladding systems in arid climates: Sport hall in Kerman

Climate change, driven by fossil fuel dependence, presents a significant challenge for the construction industry, particularly in energy-intensive regions like arid climates. This research investigates the potential of integrating machine learning and parametric optimization to enhance the energy efficiency of spatial structure domes in such environments. Focusing on a sports pavilion in Kerman, Iran, the study examines the crucial role of cladding systems in building energy performance. Employing a rigorous four-phase methodology, the research optimizes dome cladding materials for hot, dry climates using a dual objective function: energy cost and material cost. The process involves a comprehensive literature review, data-driven material selection, advanced energy simulations, and optimization analysis. Parametric modeling tools (Rhino, Grasshopper, Honeybee) facilitate the comparative analysis of various cladding systems. Multivariate Polynomial Regression (MPR) enables predictive modeling of energy consumption and material costs, streamlining the design process for architects. The optimized solution is a hybrid cladding model composed of 10 % polycarbonate and 90 % aluminum. Analysis reveals that the hybrid system offers superior energy optimization compared to pure aluminum (4.58 %) and polycarbonate (5.70 %). While polycarbonate has a lower initial material cost, the hybrid system achieves a balance between material expenditure and long-term energy efficiency. This highlights the importance of considering life-cycle costs when evaluating building envelope materials. This research advances a framework that leverages machine learning and parametric design for building envelope optimization. This framework empowers architects and engineers to create energy-efficient structures within arid environments, promoting a more sustainable built environment.

Recycling metal-organic framework residues (MOFRs) as bifunctional additives in fabricating porous ceramic membranes

In this work, Fe-MOF residues (Fe-MOFRs) were recycled and reused as a kind of bifunctional additives in the preparation of alumina ceramic membranes. To prevent the unwanted aggregation and grain growth of Fe-MOFR derived Fe2O3 nanoparticles at elevated temperature, Fe-MOFRs were premeditatedly introduced into the alumina powder matrix to construct the composite membrane layer. Results showed that the introduction of MOFRs could reduce the thickness of the membrane layer, attributing to the sacrificial organic linkers and high activity of Fe-MOFR-derived Fe2O3 nanoparticles. However, the thickness of the formed composite membrane layer abnormally increased once MOFRs were overloaded due to the aggregation. Impressively, the surface roughness and Young modulus of the membrane layer were characterized using atomic force microscopy (AFM). The Young modulus of pure alumina membranes showed the same trend as the height, while the trend gradually reversed once Fe-MOFRs were introduced, suggesting that the binding strength between the Fe-MOFR derived Fe2O3 nanoparticles were greatly enhanced. The composite membranes showed improved pure water flux and reduced filtration resistance.

Preparation of High-Performance Transparent Al2O3 Dielectric Films via Self-Exothermic Reaction Based on Solution Method and Applications.

As the competition intensifies in enhancing the integration and performance of integrated circuits, in accordance with the famous Moore's Law, higher performance and smaller size requirements are imposed on the dielectric layers in electronic devices. Compared to vacuum methods, the production cost of preparing dielectric layers via solution methods is lower, and the preparation cycle is shorter. This paper utilizes a low-temperature self-exothermic reaction based on the solution method to prepare high-performance Al2O3 dielectric thin films that are compatible with flexible substrates. In this paper, we first established two non-self-exothermic systems: one with pure aluminum nitrate and one with pure aluminum acetylacetonate. Additionally, we set up one self-exothermic system where aluminum nitrate and aluminum acetylacetonate were mixed in a 1:1 ratio. Tests revealed that the leakage current density and dielectric constant of the self-exothermic system devices were significantly optimized compared to the two non-self-exothermic system devices, indicating that the self-exothermic reaction can effectively improve the quality of the dielectric film. This paper further established two self-exothermic systems with aluminum nitrate and aluminum acetylacetonate mixed in 2:1 and 1:2 ratios, respectively, for comparison. The results indicate that as the proportion of aluminum nitrate increases, the overall dielectric performance of the devices improves. The best overall performance occurs when aluminum nitrate and aluminum acetylacetonate are mixed in a ratio of 2:1: The film surface is smooth without cracks; the surface roughness is 0.747 ± 0.045 nm; the visible light transmittance reaches up to 98%; on the basis of this film, MIM devices were fabricated, with tested leakage current density as low as 1.08 × 10-8 A/cm2 @1 MV and a relative dielectric constant as high as 8.61 ± 0.06, demonstrating excellent electrical performance.

Quantitative Interpretation of Potentiodynamic Polarization Curves Obtained at High Scan Rates in Scanning Electrochemical Cell Microscopy.

Scanning electrochemical cell microscopy is becoming the tool of choice for the investigation of localized metal corrosion. Typically, potentiodynamic polarization measurements in scanning electrochemical cell microscopy are performed at high potential scan rates. However, Tafel extrapolation applied to high-scan-rate potentiodynamic polarization curves would yield inaccurate corrosion kinetics due to the interference of double-layer charging current or mass transport of species in the metal oxide. Instead, the high field model was used to simulate the potentiodynamic polarization curves of pure aluminum at 25, 50, 100, and 200 mV/s in neutral and acidic phosphate solutions, thus enabling quantitative analysis of local corrosion kinetics by fitting the potentiodynamic polarization curve.

Thermal cycle behaviour of plasma sprayed thermal barrier coatings on cast iron substrate for the application of liner of internal combustion engine

In the present scenario, research on Thermal Barrier Coatings (TBCs) is attracting significant attention in high-temperature applications due to the rising demand in industrial applications, such as gas turbine blades and internal combustion engine components. To meet these demands, it is essential to enhance the mechanical and oxidation properties of thermal barrier coatings. The atmospheric plasma spray methodology for producing these coatings has become a central focus in recent times. In this work, TBCs were prepared by blending pure alumina and Yttria-Stabilized Zirconia (YSZ) in equal proportions. Extensive study of TBCs carried out under high-temperature conditions through thermal cycle tests at elevated temperatures, around 850 °C. A total of 350 thermal cycles were conducted, and microstructures of the coating surface were examined at 150, 250, and 350 cycles. High-temperature stress, generated due to the sintering of the coating, also influences the life of the coatings. Specimen with a topcoat thickness of 300 μm, exhibited good thermal shock resistance compared to the specimens with topcoats of thickness of 100 μm and 200 μm. The effects of process parameters, porosity, and thermal shock resistance are presented in detail. The topcoat with a thickness of 300 μm demonstrated excellent thermal shock resistance and reduced formation of thermally grown oxide (TGO). The porosity of the coating, found to be between 2% and 3%, contributed to its dense nature, effectively reducing oxidation rates and enhancing the coating's lifespan under cyclic high-temperature conditions.

Dual Grain Refinement Effect for Pure Aluminum with the Addition of Micrometer-Sized TiB2 Particles.

The inefficiency of grain refinement processes has traditionally been attributed to the limited utilization of heterogeneous nucleation particles within master alloy systems, resulting in the formation of abundant inactive particles. This study aims to investigate the alternative influences of particles by incorporating external micrometer-sized TiB2 particles into the grain refinement process. Through a series of experiments, the refinement efficiency, grain refinement mechanism, and resultant microstructure of TiB2 particle-induced grain refinement specimens are comprehensively examined using various microscopy and analytical techniques, including polarization microscopy (OM), scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and transmission electron microscopy (TEM). Our findings demonstrate a direct correlation between increased levels of TiB2 particles and enhanced grain refinement efficiency. Moreover, the microstructure analysis reveals the distribution of TiB2 particles along grain boundaries, forming a coating due to self-assembly phenomena, while regions with a lower particle content may exhibit irregular grain structures. DSC analysis further confirms reduced undercooling, indicating the occurrence of heterogeneous nucleation events. However, TEM observations suggest that heterogeneous nucleation is not significantly influenced by the growth restriction factor attributed to TiAl3 2DC compounds. The grain refinement mechanism involving TiB2 particles is elucidated to entail both heterogeneous nucleation and physical growth restriction effects. Specifically, a reduction in average grain size is attributed not only to heterogeneous nucleation but also to the physical growth restriction effect facilitated by the TiB2 particle coating. This study offers insights into leveraging particles that do not participate in heterogeneous nucleation within master alloy-based grain refinement systems.

Localized Surface Modification during Alternating Current Scanning Electrochemical Microscopy: Origin and Mechanism

In the current study, we report for the first time the observation of unintended localized surface modification on commercially pure aluminum (Al) during an alternating current scanning electrochemical microscopy (AC-SECM) analysis, its origin, and the probable mechanism responsible for it. Application of an AC perturbation potential (∼100 mV amplitude at ∼100 kHz frequency) to the Platinum ultramicroelectrode (Pt UME), during AC-SECM in acidic, neutral chloride, tap water, and alkaline electrolytes was found to cause surface modification on the scanned region of Al. An increase in the local pH of the electrolyte between the UME and the Al substrate, irrespective of the electrolyte pH (3–11) and UME biasing conditions, led to the local surface modification. The reason for the enhancement of local pH is attributed to the occurrence of higher rates of cathodic reduction reactions than that of anodic oxidation reactions. The reduction of dissolved oxygen/protons/water in the electrolytes led to the generation or consumption of OH−/H+ ions, respectively, and thus increased the pH, whereas the oxidation of Pt UME/Al surfaces decreased the pH with the generation of H+ or consumption of OH− ions. These results contribute significantly to accurately analyzing Al and its alloys using the AC-SECM technique.

Pyrometallurgical processing of manganese ore

Manganese ore contains valuable oxides, such as manganese oxide (MnO2/Mn2O3/Mn3O4), iron oxide (Fe2O3) and silica (SiO2). In the present study, an attempt has been made to separate these oxides through pyrometallurgical processing routes for the extraction of ferromanganese and silicomanganese. Lean manganese ores were subjected to ball milling followed by carbothermic reduction at a temperature of 1200 °C for 2 h. The reduced ores were then subjected to wet magnetic separation to obtain the magnetic constituents in the reduced ores. It was observed that it is not possible to remove the silica content from the ore. It appeared that the reduced sample had oxides of iron, silicon and manganese after its wet magnetic separation. The magnetic constituents were subjected to metallothermic reduction through pure aluminium powders to recover valuable metals/alloys.

Formation mechanism of nanopores in dense films of anodic alumina

Constant-current anodization of pure aluminum was carried out in non-corrosive capacitor working electrolytes to study the formation mechanism of nanopores in the anodic oxide films. Through comparative experiments, nanopores are found in the anodic films formed in the electrolytes after high-temperature storage (HTS) at 130 °C for 240 h. A comparison of the voltage−time curves suggests that the formation of nanopores results from the decrease in formation efficiency of anodic oxide films rather than the corrosion of the electrolytes. FT-IR and UV spectra analysis shows that carboxylate and ethylene glycol in electrolytes can easily react by esterification at high temperatures. Combining the electronic current theory and oxygen bubble mold effect, the change in electrolyte composition could increase the electronic current in the anodizing process. The electronic current decreases the formation efficiency of anodic oxide films, and oxygen bubbles accompanying electronic current lead to the formation of nanopores in the dense films. The continuous electronic current and oxygen bubbles are the prerequisites for the formation of porous anodic oxides rather than the traditional field-assisted dissolution model.

Improvement of wear-resistant and thermal conductivity of aluminum matrix composite reinforced AL2O3/SiCw/Mg powder

Technological progress demands the development of materials that have special characteristics such as high strength, stiffness, light weight, and good thermal conductivity at a low price. The development of hybrid metal matrix composites is the most important field in advanced materials science engineering. This research determines about aluminum matrix composites (AMC) reinforced with alumina (Al2O3), Silicon carbide whisker (SiCw), and magnesium (Mg) addition. The matrix is made of 90 % pure aluminum powder, and commercially available reinforcing materials include Al2O3, SiCw, and Mg. Objectives include variation of reinforcement fraction and matrix, sintering holding temperature and time. The selection of the sample making process using powder technology followed by the sintering process at different temperatures namely 350, 450 and 550 °C with variations in holding time of 1, 2 and 3 hours. The purpose of this study was to determine the effect of variations in the fraction of reinforcement and sintering treatment on the properties of wear resistance, hardness and thermal conductivity of aluminum matrix composites. The results showed that the composition ratio of reinforcement to aluminum in sintering treatment significantly affected the mechanical properties. The wear resistance of the material shows excellent performance, namely wear resistance of 0.000065 gr/s, hardness of 45.234 VHN and thermal conductivity of 184.855 Watt/m °C, at a reinforcement composition combination of 10 %AL2O3, 10 %SiCw and 20 %Mg and a sintering temperature of 550 °C. This indicates that the Aluminum matrix composite reinforced with Al2O3/(SiCw/Mg) is able to support the friction load due to its low wear rate, good hardness, and good thermal conductivity. This material is very suitable to be used as tribology material, brake element, especially brake drum

Effect on Ti/Mg isothermal oxidation of refinement microstructure and tribological behaviour of pure aluminium alloy by plasma spray coating

Effect on Ti/Mg isothermal oxidation of refinement microstructure and tribological behaviour of pure aluminium alloy by plasma spray coating

The wettability of pure liquid aluminum on oxide substrates

AbstractOxide particles are considered to be one of the reasons for the stability of cellular porous Al foam. Thus, the contact angle (ө) of molten pure aluminum on oxide substrates, including Al2O3, CaO·2Al2O3 (CA2), CaO·6Al2O3 (CA6), mullite (3Al2O3·2SiO2), and SiO2 was measured in a vacuum heating microscope at a temperature of 950°C to determine the value of wettability of molten aluminum on various oxides. Thereafter, the measured contact angles followed the tendency as mullite (155°) > CA6 (152°) > MgAl2O4 (151°) > Al2O3 (149°) > SiO2 (124°) > CA2 (100°). Furthermore, the cross‐sectional area between molten aluminum and substrates was thoroughly analyzed, and the reaction products, such as the Al2O3 layer at the interface, have been detected. Thermo‐Calc, with the combination of available databases, was used to perform thermodynamic simulations and to discuss and predict possible reactions under the current experimental conditions.

An Evaluation of the Impact Effect on the Surface Microstructure and Its Induced Temperature Changes during Ultrasonic-Assisted Micro-Forging.

In the field of ultrasonic-assisted micro-forming, in addition to acoustic softening, impact effects also play a significant role, especially in terms of influencing the deformation behavior of surfaces, such as by generating more deformation on surface asperity. In this study, to understand the mechanisms involved in the effect of an impact, ultrasonic-assisted micro-forging tests were conducted on commercially pure copper, pure aluminum, and pure titanium. A method that can measure the increment in the temperature during ultrasonic vibration was developed. As a result, changes in the surface temperature of the material under the impact effect and acoustic softening were measured. It is indicated that, during ultrasonic vibration, the heat generated through acoustic softening is very limited and the main heat increase occurs after the impact effect. Once the impact effect occurs, the surface temperature increases with increasing amplitude. Nevertheless, for materials with different crystal structures, the influences of the impact effect are also different. The surfaces of copper and aluminum soften, creating more surface deformation, but the exact opposite effect is seen on a titanium surface. Observing the evolution of the microstructure on the material surface with EBSD demonstrates that the impact effect on FCC materials can reach deeper below the surface in terms of temperature diffusion compared to titanium. Meanwhile, the impact effect in the case of titanium causes the regeneration of twinning, which is reduced under the influence of the acoustic softening effect, consequently resulting in strain hardening.

Mechanical and electrochemical behaviour of electron beam welded commercially pure aluminium using oscillating beam

Mechanical and electrochemical behaviour of electron beam welded commercially pure aluminium using oscillating beam