The influence Cl- on stress corrosion of 7xxx series aluminium alloys studied by experimental and simulation technology.

The stress corrosion behavior of 7xxx series aluminium alloys in different concentrations NaCl solution was studied, and numerical simulation was conducted in COMSOL Multiphysics based on experimental results. Different stresses were applied on the experiment pieces, the pitting crater deepened with the change of stress level. The corrosion rate increased with the raising stress. There is no positive correlation between stress corrosion degree and chloride ion concentration. The most severe corrosion occurs in 5.0 wt% NaCl solution instead of 6.0 wt% NaCl solution due to the increase of water film conductivity and decrease of solubility of oxygen under high Cl- environment. The finite element model was used to analyze the stress distribution on aluminium alloy surface, to describe the dynamic equation of anodic dissolution of metal due to elastic and plastic deformation. Corrosion occurs mainly in stress concentrated areas. When the stress loading exceeds a certain threshold, plastic strain occurs on the surface of both the specimen and the structural part, the corrosion current density increases instantaneously, and the corrosion behavior in the stress concentration area gradually intensifies. The survey can provide practical theoretical guidance for predicting stress corrosion and extending the service life of equipment in (harsh) marine environments.

A New Structural Motif in Aggregation of Methylalumoxanes: Non-hydrolytic Route by the Alkylation of Dicarboxylic Acids.

Alumoxanes are typically produced via controlled hydrolysis of short-chain alkyl aluminium compounds which leads to oligomeric species that are usually difficult to obtain in crystalline form. Simultaneously, various alternative non-hydrolytic approaches to alumoxanes have also been used. In this work, we report on a new methylalumoxane scaffold derived from the alkylation of a series of dicarboxylic acids: itaconic acid (HO2CCH2C(=CH2)CO2H), succinic acid (HO2CCH2CH2CO2H) and homophthalic acid (HO2CCH2C6H4CO2H). The reactions of AlMe3 with a selected dicarboxylic acid in the molar ratio 4:1 conducted at elevated temperature occur with double methylation of each carboxylic group and provide to the formation of a new methylalumoxane aggregate, Me10Al6O4, flanked by methylaluminium diolate units. We also aimed to obtain dialkylaluminium derivatives of dicarboxylic acids by the controlled reaction of the appropriate acid with AlMe3 in the 1:2 stoichiometry. While the synthesis of organoaluminium derivatives of flexible aliphatic dicarboxylic acids (itaconic and succinic acids) is challenging due to their insolubility, the related homophtalate compound readily forms a molecular tetranuclear cluster, [(homophtalate)(AlMe2)2]2. The molecular and crystal structures of the resulting compounds were determined via NMR spectroscopic analysis and single crystal X-ray diffraction crystallography.

Bis-Silylene-Supported Aluminium Atoms with Aluminylene and Alane Character.

The suitability of electron-rich bis-silylenes, specifically the neutral chelating [SiII(Xant)SiII] ligand (SiII = PhC(NtBu)2Si, Xant = 9,9dimethylxanthene) and the anionic [SiII(NAcrid)SiII)]‒ pincer ligand (NAcrid = 2,7,9,9-tetramethylacridane), has been successfully probed to stabilize monovalent bis-silylene-supported aluminium complexes (aluminylenes). At first, the unprecedented aluminium(III) iodide precursors [SiII(Xant)SiII]AlI2+ I‒ 1 and [SiII(NAcrid)SiII)]AlI2 2 were synthesized using AlI3 and [SiII(Xant)SiII] or [SiII(NAcrid)SiII)]Li(OEt2)], respectively, and structurally characterized. While reduction of 1 with KC8 led merely to unidentified products, the dehalogenation of 2 afforded the dimer of the desired {[SiII(NAcrid)SiII)]Al:} aluminylene with a four-membered SiIV2AlIII2 ring. Remarkably, the proposed aluminylene intermediates [SiII(Xant)SiII]AlII and {[SiII(NAcrid)SiII)]Al:} could be produced through reduction of 1 and 2 with Collman's reagent, K2Fe(CO)4, and trapped as AlI:→Fe(CO)4 complexes 5 and 6 , respectively. While6is stable in solution,5loses one CO ligand in solution to afford the silylene- and aluminylene-coordinated iron(0) complex7. The electronic structures of the novel compounds were investigated by Density Functional Theory calculations.

Designed Synthesis of an Aluminum Molecular Ring Based Rotaxane and Polyrotaxane.

Mechanically interlocked molecules, such as rotaxanes, have drawn significant attention within supramolecular chemistry. Although a variety of macrocycles have been thoroughly explored in rotaxane synthesis, metal-organic macrocycles remain relatively under-investigated. Aluminum molecular rings, with their inner cavities and numerous binding sites, present a promising option for constructing rotaxanes. Here, we introduce an innovative "ring-donor···axle-acceptor" motif utilizing Al8 molecular rings, enabling the stepwise assembly of molecules, complexes, and polymers through tailored coordination chemistry. This novel approach can not only be applied to macrocycle-based systems like catenanes but also enhance specific functionalities progressively.

Low valence triel (I) systems as hydrogen bond acceptors and their stability with respect to triel (III) compounds.

A theoretical study of the complexes formed by carbene like Al(I), Ga(I), In(I) and Tl(I) compounds with hydrogen bond donors (HBD), XH (HCCH, HSH ,HOH, HCN, HCl, HBr, HF, and HNC) have been carried out at MP2 computational level. The isolated triel(I) compounds show a negative region of the molecular electrostatic potential region associated with the triel atom suitable to interact with electron deficient groups. This region is associated to a lone pair based on the ELF analysis and to the location of the HOMO orbital. The complexes are similar to those found in nitrogen heterocyclic carbenes (NHC) with HBD. In addition, the oxidative addition reactions of those complexes to yield the corresponding valence III compounds have been characterized. The Al(III) compounds are much more stable than the corresponding Al(I) complexes. However, the stability of the triel(III) compounds decreases with the size of the triel atom and for the thallium derivatives, the Tl(I) complexes are more stable than the Tl(III) compounds in accordance with the number of the structures found in the CSD. The barrier of the TS connecting the triel(I) and triel(III) systems increases with the size of the triel atoms.

The stem cell niche transcription factor ETHYLENE RESPONSE FACTOR 115 participates in aluminum-induced terminal differentiation in Arabidopsis roots.

Aluminum-dependent stoppage of root growth requires the DNA damage response (DDR) pathway including the p53-like transcription factor SUPPRESSOR OF GAMMA RADIATION 1 (SOG1), which promotes terminal differentiation of the root tip in response to Al dependent cell death. Transcriptomic analyses identified Al-induced SOG1-regulated targets as candidate mediators of this growth arrest. Analysis of these factors either as loss-of-function mutants or by overexpression in the als3-1 background shows ERF115, which is a key transcription factor that in other scenarios is rate-limiting for damaged stem cell replenishment, instead participates in transition from an actively growing root to one that has terminally differentiated in response to Al toxicity. This is supported by a loss-of-function erf115 mutant raising the threshold of Al required to promote terminal differentiation of Al hypersensitive als3-1. Consistent with its key role in stoppage of root growth, a putative ERF115 barley ortholog is also upregulated following Al exposure, suggesting a conserved role for this ATR-dependent pathway in Al response. In contrast to other DNA damage agents, these results show that ERF115 and likely related family members are important determinants of terminal differentiation of the root tip following Al exposure and central outputs of the SOG1-mediated pathway in Al response.

Corrosion resistance of aluminum against acid activation in 1.0 M HCl by symmetrical ball - type zinc phthalocyanine.

The inhibition effect of symmetrical Ball - type Zinc Phthalocyanine on Aluminum in 1mol/L hydrochloric acid was analyzed by electrochemical techniques. A novel ball-type zinc phthalocyanine (Zn-Pc) inhibitor has been synthesized and verified utilizing FTIR, nuclear magnetic resonance (1H NMR and 13C NMR), MALDI-TOF MS, and absorption spectroscopy (UV-Vis). In addition, laser-induced breakdown and photoluminescence spectroscopy were employed for additional study. Weight loss technique was employed to investigate the corrosion inhibition effectiveness of the synthesized Zn-Pc on Aluminum in 1mol/L hydrochloric acid at the range of variation temperatures (293-333 K). The inhibition efficiency of Zn-Pc increased with higher concentrations of Zn-Pc and decreased as the temperature increased. Furthermore, Zn-Pc demonstrated outstanding outcomes, achieving 72.9% at a very low inhibitor concentration (0.4 mmol/L) at 298 K. The experimental data for Zn-Pc Aluminum in 1mol/L hydrochloric acid obeys the Langmuir adsorption isotherm. Moreover, the corrosion system's thermodynamic parameters and activation energy were determined. Quantum chemical calculations applying the (DFT) Density Functional Theory method was conducted and applied in this study. These calculations played a pivotal role in elucidating molecular structures and reactivity patterns. Through DFT, numerous reactivity indicators were computed, providing valuable insights into the chemical behavior of the studied compounds. These indicators, such as frontier molecular orbitals, electron density, and molecular electrostatic potential, were subsequently correlated with experimental data.

Effects of copper, and aluminium in ionic, and nanoparticulate form on growth rate and gene expression of Setaria italica seedlings.

This study aims to determine the effects of copper, copper oxide nanoparticles, aluminium, and aluminium oxide nanoparticles on the growth rate and expression of ACT-1, CDPK, LIP, NFC, P5CR, P5CS, GR, and SiZIP1 genes in five days old seedling of Setaria italica ssp. maxima, cultivated in hydroponic culture. Depending on their concentration (ranging from 0.1 to 1.8 mg L-1), all tested substances had both stimulating and inhibiting effects on the growth rate of the seedlings. Copper and copper oxide-NPs had generally a stimulating effect whereas aluminium and aluminium oxide-NPs at first had a positive effect but in higher concentrations they inhibited the growth. Treating the seedlings with 0.4 mg L-1 of each tested toxicant was mostly stimulating to the expression of the genes and reduced the differences between the transcript levels of the coleoptiles and roots. Increasing concentrations of the tested substances had both stimulating and inhibiting effects on the expression levels of the genes. The highest expression levels were usually noted at concentrations between 0.4 and 1.0 mg/L of each metal and metal nanoparticle, except for SiZIP1, which had the highest transcript amount at 1.6 mg L-1 of Cu2+ and at 0.1-0.8 mg L-1 of CuO-NPs, and LIP and GR from the seedling treated with Al2O3-NPs at concentrations of 0.1 and 1.6 mg L-1, respectively.

Friction Investigation of Closed-Cell Aluminium Foam during Radial-Constrained Test.

The energy-absorbing capacity and friction phenomena of different closed-cell aluminium foam-filled Al tube types are investigated through experimental compression tests. Concerning the kind of investigation, free, radial-constrained and friction tests occurred. The radial-constrained compression test results confirm that the process requires significantly more compression energy than without the constrain. Pushing away different pre-compressed foams inside the aluminium tube, the static and kinematic frictional resistances can be determined and the energy required to move them can be calculated. Knowing the value of the energy required for the frictional resistance, we can obtain how much of the energy surplus in radially inhibited compression is caused by the friction phenomena. The main goal present study is to reveal the magnitude of friction between the foam and the wall of the tube during the radially constrained test. The investigation used 0.4 and 0.7 g/cm3 density closed-cell aluminium foam whilst a compressive test was applied where the force-displacement data were recorded to calculate the absorbed energy due to friction. Considering the results of the test, it can be stated that 18% of the invested energy was used to overcome friction in the case of lighter foam and almost 23% with 0.7 g/cm3 foam during the radial-constrained test.

Synergistic effect of Al2O3-decorated reduced graphene oxide on microstructure and mechanical properties of 6061 aluminium alloy.

In this study, Al6061 alloy matrix composites reinforced Al2O3-decorated reduced graphene oxide (Al2O3/RGO) with 0.1, 0.3 and 0.5 weight present (wt%) were successfully fabricated using high energy ball milling and hot extrusion techniques. The microstructures of these Al2O3/RGO/Al6061 aluminum matrix composites (Al MMCs) were characterized. The results showed that Al2O3/RGO were uniformly distributed within the Al6061 matrix and tightly bonded to the matrix. Al2O3 encapsulation on RGO surface would prevent the formation of Al4C3 brittle phase in matrix, ensuring that there was no reaction between the reinforcement and the matrix Al6061. Tensile strength and Vickers hardness tests demonstrated that the mechanical properties of Al MMCs significantly increased with addition of Al2O3/RGOs. Remarkably, Al MMCs with 0.1 wt% reinforcement showed tensile yield and tensile strengths of 270 MPa and 286 MPa, respectively, which were 49% and 43% higher than those of pure Al6061 prepared using the same process. Furthermore, the 0.1 wt% Al2O3/RGO composite also showed the best plastic deformation capability in considering of the strength.

A Comparative Evaluation of Powder Characteristics of Recycled Material from Bronze Grinding Chips for Additive Manufacturing.

In the manufacturing process of ship propellers, large quantities of grinding chips are generated. These grinding chips result from the finishing of the blade surfaces after the primary casting process of the propeller. The aim of this study was to investigate and compare different preparation processes used to produce chip powders with sufficient powder quality for the additive manufacturing process of directed energy deposition. The preparation of the samples was performed through different sieving, milling and re-melting processes. For the characterization of the prepared samples, powder analysis according to relevant industry standards was carried out. It was found that the re-melting processes result in superior powder quality for additive manufacturing in terms of particle size, morphology, and flowability. For some characteristics, the powder exhibits even better properties than those of commercial powders. Furthermore, the powder properties of the milled samples demonstrate a promising potential for use in additive manufacturing.

Evolution of Material Properties and Residual Stress with Increasing Number of Passes in Aluminium Structure Printed via Additive Friction Stir Deposition.

Additive friction stir deposition (AFSD) is an emerging solid-state additive manufacturing process with a high deposition rate. Being a non-fusion additive manufacturing (AM) process, it significantly eliminates problems related to melting such as cracking or high residual stresses. Therefore, it is possible to process reactive materials or high-strength alloys with high susceptibility to cracking. Although the residual stresses are lower in this process than with the other AM processes, depending on the deposition path, geometry, and boundary conditions, residual stresses may lead to undesired deformations and deteriorate the dimensional accuracy. Thermal cycling during layer deposition, which also depends on the geometry of the manufactured component, is expected to affect mechanical properties. To this day, the influence of the deposit geometry on the residual stresses and mechanical properties is not well understood, which presents a barrier for industry uptake of this process for large-scale part manufacturing. In this study, a stepped structure with 4, 7, and 10 passes manufactured via AFSD is used to investigate changes in microstructure, residual stress, and mechanical property as a function of the number of passes. The microstructure and defects are assessed using scanning electron microscopy and electron backscatter diffraction. Hardness maps for each step are created. The residual stress distributions at the centreline of each step are acquired via non-destructive neutron diffraction. The valuable insights presented here are essential for the successful utilisation of AFSD in industrial applications.

Naringenin mitigates nanoparticulate-aluminium induced neuronal degeneration in brain cortex and hippocampus through downregulation of oxidative stress and neuroinflammation.

Alumunium usage and toxicity has been a global concern especially an increased use of nanoparticulated aluminum (Al-NPs) products from the environment and the workplace. Al degrades in to nanoparticulate form in the environment due to the routine process of bioremediation in human body. Al-NPs toxicity plays key role in the pathophysiology of neurodegeneration which is characterised by the development of neurofibrillary tangles and neuritic plaques which correlates to the Alzheimer's disease. This study evaluated the Al-NPs induced neurodegeneration and causative behavioral alterations due to oxidative stress, inflammation, DNA damage, ß-amyloid aggregation, and histopathological changes in mice. Furthermore, the preventive effect of naringenin (NAR) as a potent neuroprotective flavonoid against Al-NPs induced neurodegeneration was assessed. Al-NPs were synthesized and examined using FTIR, XRD, TEM, and particle size analyzer. Mice were orally administered with Al-NPs (6 mg/kg b.w.) followed by NAR treatment (10 mg/kg b.w. per day) for 66 days. The spatial working memory was determined by novel object recognition, T-maze, Y-maze, and Morris Water Maze tests. We measured nitric oxide, advanced oxidation of protein products, protein carbonylation, lipid peroxidation, superoxide dismutase, catalase, glutathione peroxidase, glutathione reductase, reduced glutathione, oxidised glutathione, and acetylcholine esterase, as well as cytokines analysis, immunohistochemistry, and DNA damage. Al-NPs significantly reduced the learning memory power, increased oxidative stress, reduced antioxidant enzymatic activity, increased DNA damage, altered the levels of cytokines, and increased ß-amyloid aggregation in the cortex and hippocampus regions of the mice brain. These neurobehavioral impairments, neuronal oxidative stress, and histopathological alterations were significantly attenuated by NAR supplementation. In conclusion, Al-NPs may be potent neurotoxic upon exposure and that NAR could serve as a potential preventive measure in the treatment and management of neuronal degeneration.

Unbounding the Future: Designing NiAl-Based Catalysts for Dry Reforming of Methane.

Dry reforming of methane (DRM), the catalytic conversion of CH4 and CO2 into syngas (H2+CO), is an important process closely correlated to the environment and chemical industry. NiAl-based catalysts have been reported to exhibit excellent activity, low cost, and environmental friendliness. At the same time, the rapid deactivation caused by carbon deposition, Ni sintering, and phase transformation exerts great challenges for its large-scale applications. This review summarizes the recent advances in NiAl-based catalysts for DRM, particularly focusing on the strategies to construct efficient and stable NiAl-based catalysts. Firstly, the thermodynamics and elementary steps of DRM, including the activation of reactants and coke formation and elimination, are summarized. The roles of Al2O3 and its mixed oxides as the support, and the influences of the promoters employed in NiAl-based catalysts over the DRM performance, are then illustrated. Finally, the design of anti-coking and anti-sintering NiAl-based catalysts for DRM is suggested as feasible and promising by tailoring the structure and states of Ni and the modification of Al-based supports including small Ni size, high Ni dispersion, proper basicity, strong metal-support interaction (SMSI), active oxygen species as well as high phase stability.

Analysis of the effect of vibrational stress relief process parameters on 2024Aluminium alloy.

In principle, after all manufacturing processes are performed, a set of residual stresses occur in the product that have their particular distribution given the manufacturing process performed. The residual stresses must be removed to achieve the desired dimensional accuracy and quality. Among stress-relieving processes performed for a piece following the manufacturing process, we can refer to thermal and vibratory stress relief (VSR). Both methods perform the same function as they enter a part or all of a piece into the plastic phase, causing a fracture of residual stresses to be released with local plastic deformations. The process is as follows: The stress induced by thermal or vibratory loads is added to the residual stresses and exceeds the yield stress. This research, which is focused on VSR, aims to evaluate the effect of the main parameters of the VSR method, including load amplitude or amount, load application frequency, and cycle numbers. The general trend of the problem is that the VSR process is performed for a piece with residual stress, and the effect of the abovementioned parameters on reducing its residual stresses is evaluated.

A simple new approach for mapping an ultrasonic tank for sonochemistry.

The most used piece of equipment for sonochemistry is the ultrasonic cleaning bath. However, what is sometimes forgotten by scientists new to sonochemistry is the vital importance of the shape and positioning of any reaction vessel in the bath to obtain the most efficient and reproducible results. In experiments using an ultrasonic bath, a glass vessel (reactor) is inserted into the water contained in the bath. The water acts as the coupling medium for the transfer of acoustic energy from the transducer to the vessel (termed indirect sonication). The position of the reaction vessel above the base of the US bath can change the energy transmitted into it over a wide range of values (in our system between 100-500 J). We have carried out a study of the vertical distribution of the ultrasound field in a common type of ultrasound bath, comparing conventional sonochemistry dosimeters with a new and very simple approach using the Ultrasonic Capillary Effect (UCE) which can be performed in any laboratory. The technique involves the use of a capillary tube, to locate the vertical positions of acoustic pressure maxima above a single transducer on the base of the bath. The results are compared with those obtained using calorimetry, iodimetry, a cavitometer and the perforation of aluminium foil. The results show that the optimum position for the reaction vessel can be located very simply using UCE.

The mechanical characteristics of an aluminum foam winding CFRP composite structure under axial compression.

To enhance the energy absorption properties of the energy-absorbing structure, carbon fiber-reinforced polymer (CFRPs) with higher specific energy absorption and porous material aluminum foam with better compressive characteristics were organically combined, and a lighter aluminum foam winding carbon fiber-reinforced polymer structure (CFRP-FA-FW) was designed. Through quasi-static compression testing, the deformation mode and energy absorption properties of CFRP-FA-FW under axial load were examined. The energy absorption and specific energy absorption of CFRP-FA-FW are both increased by 113.55 % and 60.73 %, respectively, compared to the simple composite structure CFRP-FA. Finite element simulation was used for the parametric analysis of the CFRP-FA-FW structure to assess the effects of the relative density of the aluminum foam, the fiber lay-up angle, and the thickness. The results reveal that the change in the relative density of aluminum foam has little impact on the failure deformation mode of CFRP-FA-FW under axial load; the structure has a higher energy absorption capacity and a smoother energy absorption process when the fiber lay-up angle is [0°/90°]ns and [45°]ns; the energy absorption capacity of CFRP-FA-FW is significantly improved by increasing the thickness of the carbon fiber lay-up, and the procedure is also more efficient.

Aluminium stress tolerance by Citrus plants: a consolidated review.

Aluminium, a metallic element abundant in soils as aluminosilicates minerals, poses a toxic threat to plants, particularly in acidic soil conditions, thereby affecting their growth and development. Given their adaptability to diverse soil and climate conditions, Citrus plants have gained significant attention regarding their tolerance to Aluminium toxicity. In the North-eastern region of India, where soils are often slightly acidic with elevated aluminium levels, Citrus species are predominantly found. Understanding the tolerance mechanisms of these Citrus fruits and screening wild Citrus species for their adaptability to abiotic stresses is crucial for enhancing fruit production. Numerous investigations have demonstrated that Citrus species exhibit remarkable tolerance to aluminium contamination, surpassing the typical threshold of 30% incidence. When cultivated in acidic soils, Citrus plants encounter restricted root growth and reduced nutrient and moisture uptake, leading to various nutrient deficiency symptoms. However, promisingly, certain Citrus species such as Citrus jambhiri (Rough lemon), Poncirus trifoliata, Citrus sinensis, and Citrus grandis have shown considerable aluminium tolerance. This comprehensive review delves into the subject of aluminium toxicity and its implications, while also shedding light on the mechanisms through which Citrus plants develop tolerance to this element.

Studies on the Evolution of Fatigue Strength of Aluminium Wires for Overhead Line Conductors.

Traditional ACSR overhead wires, which consist of a high-strength steel core and several layers of aluminium wires, are currently the most popular overhead line conductor (OHL) design globally. Operating conditions, particularly operating under varying stresses from Karman vortices, lead to the fatigue cracking of wires of the outer layer, followed by wires of the inner layers. Karman vortices are formed by the detachment of a laminar wind stream flowing around the conductor, which causes vibrations in the conductor called wind or aeolian oscillations. Aluminium wires are manufactured using standard batch material drawing technology. Although the fatigue strength of such wires is not standardised, there are various criteria for evaluating this characteristic, as well as established limits on the number of cycles needed to break the first wires of the outer layer. Fatigue strength also strongly depends on the geometric structure of the wire and its operating conditions. The article analyses the influence of the mechanical condition of aluminium wires used in ACSR cables on their fatigue strength. We then present results from aluminium wire fatigue tests conducted on a specially constructed test rig. In addition, fatigue cracks were interpreted using scanning microscopy.