Reaction of an Al‐centered anion with toluene proceeded to form C−H cleaved product with a perfect meta‐selectivity and a relatively small kinetic isotope effect (KIE, kH/kD=1.51). DFT calculations ...suggested a two‐step reaction mechanism and electronically controlled meta‐selectivity arising from the electron‐donating methyl group. The reaction with other mono‐substituted arenes was also investigated.
Reaction of an Al‐centered anion with toluene proceeded to form C−H cleaved product with a perfect meta‐selectivity and a relatively small kinetic isotope effect (KIE, kH/kD=1.51). DFT calculations suggested a two‐step reaction mechanism and electronically controlled meta‐selectivity arising from the electron‐donating methyl group. The reaction with other mono‐substituted arenes was also investigated.
A greenhouse study was conducted to determine if concentrations of fluoride (F), which would be added to acid soils via P fertilisers, were detrimental to barley root growth. Increasing rates of F ...additions to soil significantly increased the soil solution concentrations of aluminium (Al) and F irrespective of the initial adjusted soil pH, which ranged from 4.25 to 5.48. High rates of F addition severely restricted root growth; the effect was more pronounced in the strongly acidic soil. Speciation calculations demonstrated that increasing rates of F additions substantially increased the concentrations of Al–F complexes in the soil. Stepwise regression analysis showed that it was the combination of the activities of AlF
2
1+ and AlF
2+ complexes that primarily controlled barley root growth. The results suggested that continuous input of F to soils, and increased soil acidification, may become an F risk issue in the future.
Addition of high rates of fluoride to strongly acidic soils can reduce barley root growth due to the toxicity of aluminium–fluoride complexes formed in soil solution.
To protect their steel structures from corrosion by cathodic protection, many harbours use aluminium sacrificial anodes, which induces aluminium release and potential contamination of the surrounding ...waters and sediments. To study the impact on Al mobility, a natural marine sediment was artificially contaminated with aluminium from different sources: sulphate or chloride salts, or sacrificial anodes. To estimate Al mobility in sediments, single (HCl) and sequential (F6) extractions were performed; they highlighted that aluminium is poorly mobile in natural sediment (HCl-leachable: 2% and F6-leachable: 9%). Contamination by aluminium salts inhibits HCl-leachability (≤2%), whereas the Al F6-leachability is intensified up to 18%, suggesting that the additional aluminium is scavenged in a mobile fraction that HCl is not able to solubilise. In case of aluminium anode contamination, sediments present surging Al HCl-leachable (15%) and F6-leachable (32%) fractions, which are related to aluminium mineralogical speciation. Indeed, contrary to the Al naturally present or introduced by salts, Al released by anodes is partly bound to the acid-soluble fraction, probably because of the integration of the released Al into the calcareous deposit produced at the anodes surfaces that finally comes away and gets mixed up with the sediment. The presence of aluminium in the acid-soluble fraction of sediments could have an important environmental impact as this fraction is easily available. Indeed, Al scavenged in the acid-soluble fraction of sediments participates in enhancing Al lability near the sacrificial anodes and may affect the surrounding ecosystems.
Particulate reinforced aluminium matrix composites (PRAMCs) are extensively substituting the conventional aluminium alloys in several applications and components in aircraft, marine, construction and ...automobile industries. Research is being carried out across the globe to enrich the mechanical, tribological and physical properties of PRAMCs using novel manufacture techniques and reinforcements. In this article, an attempt is made to analyse the influence of the different weight fraction of aluminum nitride (AlN) particle reinforced composites. Aluminium alloy AA7075 was reinforced with several quantities (0, 5, 10 and 15 wt%) of AlN through stir casting route. The microstructures, as well as mechanical properties of the manufactured composites are analysed. The manufactured composites were inspected by using Optical Microscope. Optical micrographs revealed the nearly uniform dissemination of reinforcement particles in the matrix alloy (AA7075). The hardness, as well as the tensile strength of the composite, has increased with the increase in weight fraction of aluminium nitride particulates in the AA7075 matrix.
The effects of Ni on the phases, microstructural evolution, hot tear susceptibility and mechanical properties of Al–6Zn-1.4Mg-1.2Cu alloys fabricated by gravity casting were investigated using X-ray ...diffraction (XRD), scanning electronic microscopy (SEM), optical microscopy, the N-Tec Hot tear and tensile test. The calculation of phase diagrams (CALPHAD) modelling was also conducted to understand the phase formation of the experimental alloys. The results showed that the secondary phases (including η-MgZn2, S–Al2CuMg and Al3Ni) are mainly distributed at grain boundary, while round S–Al2CuMg particles are also found in α-Al matrix. Ni only exists as Al3Ni with different morphologies and its number density ascends with the increase of Ni content in alloys, which also significantly improves the hot tear resistance. As a result, the increased Ni in the alloys remarkably improves the ultimate tensile and yield strength, while the elongation increases when Ni < 0.6 wt% followed by decreases when Ni > 0.6 wt%.
•Ni in Al-Zn-Mg-Cu alloys exists as Al3Ni only and no effect on the phase formation of η-MgZn2 and S–Al2CuMg.•Ni in Al-Zn-Mg-Cu alloys decreases TV and CSC*, thus improving the hot tear resistance.•When Ni < 0.6 wt.% , Ni improves the strength and elongation of Al–Zn–Mg–Cu–Ni alloys.•When Ni > 0.6 wt.%, the strength is increased but the elongation is decreased in Al–Zn–Mg–Cu–Ni alloys.
Based on a latest finding on Al-water reaction, we studied the hydrogen production behaviors activated by gallium based liquid metal where the mass percentage of Al was less than 1% in an alkaline ...environment. Three kinds of room temperature liquid binary alloy including Ga–In, Ga–Sn and Ga–Zn were tested and compared with pure gallium. It was shown that the hydrogen production rate activated by Ga–In alloy was far below than that of pure gallium, while Ga–Sn and Ga–Zn run slightly slower. Aiming to optimize the catalytic performance of pure gallium, we further performed researches to clarify its practical features. We divided five times to add equivalent Al block into pure gallium and found that the rate and quantity of hydrogen production kept unchanged in each batch addition, which suggested that liquid metal as catalyst was activated continuously without impurities mixing to impede catalytic effect. In addition, components analysis of the residual precipitates after reaction with XRD also indicated that there was only Al(OH)3 but no gallium or its derivatives. These findings as clarified by this article can help guide future high performance hydrogen generation and reuse of the liquid metal catalyst.
•Four liquid metals as Al-water reaction catalysts were contrastively investigated.•Ga works as the best than Ga–In, Ga–Sn and Ga–Zn to activate Al-water reaction.•Hydrogen generation allows continuous utilization of liquid metal catalyst.•XRD analysis indicated that liquid metal could be easily separated and reused.
Nowadays, a transportation industry creates a lot of metal scrap because production and use of cars are on the increase worldwide. This is based on the fact that increase in the production of cars ...increases usage of aluminium alloys in transportation applications. Therefore, it is necessary to reduce the production of components from primary aluminium alloy and increase their replacement with secondary—recycled—aluminium alloys because the production of recycled aluminium alloys is less expensive and less energy-intensive than the creation of new aluminium alloy through the electrolysis. In addition, the recycled aluminium alloys have comparable microstructural parameters and properties as the same primary aluminium alloys.
Uptake of the alkalis K and Na by calcium silicate hydrate (C-S-H) and calcium alumina silicate hydrate (C-A-S-H) of molar Ca/Si ratios=0.6 to 1.6 and molar Al/Si ratio=0 or 0.05 has been studied at ...20°C. Alkalis are thought to be bound in the interlayer space of C-A-S-H and show preferred uptake by lower Ca/Si ratios and by higher alkali concentrations. A consequence of alkali uptake into C-A-S-H is a rearrangement of the C-A-S-H structure. Less calcium is present in the interlayer and shorter silica chains are observed for the same molar Ca/Si ratio.
No significant difference was observed between sodium and potassium uptake. Equilibration times of 91days to 1year or the solid phase being either C-S-H or C-A-S-H had seemingly no effect on alkali uptake.
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