Microstructure investigation of equal channel angular pressed aluminium by X‐ray diffraction and scanning electron microscopy

In the present work, investigations on the microstructure of a commercial purity 1100 aluminum that had been subjected to moderate to strong deformation (strains of 1 to 4) by equal channel angular pressing (ECAP) were carried out using X‐ray diffraction (XRD) and scanning electron microcopy (SEM). A significant grain refinement and development of heterogeneous microstructure after ECAP were observed. High precision XRD and SEM investigations provided useful results on the dissolution of coherent iron rich precipitates, previously formed in the aluminium matrix, by ECAP deformation process. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Biaxial Q-shearing of 27Al 3QMAS NMR spectra: Insight into the structural disorder of framework aluminosilicates

In this contribution, we present the application potentiality of biaxial Q-shearing of ²⁷Al 3QMAS NMR spectra in the analysis of structural defects of aluminium units in aluminosilicates. This study demonstrates that the combination of various shearing transformations of the recorded ²⁷Al 3QMAS NMR spectra enables an understanding of the broadening processes of the correlation signals of disordered framework aluminosilicates, for which a wide distribution of ²⁷Al MAS NMR chemical shifts and quadrupolar parameters (i.e., second-order quadrupolar splitting and quadrupole-induced chemical shifts) can be expected. By combining the suitably selected shearing transformation procedures, the mechanisms of the formation of local defects in aluminosilicate frameworks, including Al/Si substitution effects in the next-nearest neighbouring T-sites, variations in bond angles, and/or variations in the physicochemical nature of charge-balancing counter-ions, can be identified. The proposed procedure has been extensively tested on a range of model aluminosilicate materials (kyanite, γ-alumina, metakaolin, analcime, chabazite, natrolite, phillipsite, mordenite, zeolite A, and zeolite Y).     

新型层状有机聚合物-无机杂化磷酸铝(AlPS-PVPA)催化剂载体材料的合成及表征

以苯乙烯-苯乙烯基膦酸共聚物、磷酸二氢钠作磷(膦)源,在温和的条件下,通过调节有机膦酸和无机磷酸的比例,合成了一系列不同化学计量比的聚(苯乙烯-苯乙烯基膦酸)-磷酸铝有机聚合物-无机杂化材料。通过FTIR、TG、N2吸附、XRD、SEM和TEM等表征手段对其进行了表征,并提出了其理想的结构模型。结果表明,这类杂化材料具有规则的层状结构和较高的热稳定性,作为催化剂载体具有潜在的应用价值。     

阳极氧化铝模板合成介孔CeO2纳米纤维及其光致发光性能

以多孔阳极氧化铝膜(AAO)为模板,将模板的纳米孔洞作为微腔反应器,以聚环氧乙烯醚-聚环氧丙烯醚-聚环氧乙烯醚三嵌段共聚物(P123)为致孔剂、Ce(NO3)3.6H2O为铈源、无水乙醇为溶剂合成前躯体,采用压力诱导的方法将前躯体注入到AAO孔道内,经加热处理后,在模板的纳米孔洞内合成了具有介孔结构的一维CeO2纳米材料。通过SEM、TEM、XRD、EDS和N2吸附-脱附进行表征,结果表明,所合成的介孔CeO2纳米纤维具有介孔结构和较大的比表面积,并考察了其光致发光性能。     

基于层层组装钴铝水滑石/聚电解质包裹碳纳米管的无酶葡萄糖传感器

采用共沉淀法合成了钴铝水滑石(CoAl-LDH),将CoAl-LDH与PSS包裹的CNTs(CNTs@PSS)通过层层自组装法构筑CNTs@PSS/CoAl-LDH多层膜电极,并将其应用于葡萄糖的分析测定。X射线衍射光谱、红外光谱和SEM表明:共沉淀法合成的CoAl-LDH具有典型的水滑石特征峰及形貌。电化学阻抗谱表明:CoAl-LDH可与CNTs@PSS均匀有效地组装构筑多层膜。电化学研究表明:CNTs的引入很好地提高了CoAl-LDH修饰电极的灵敏度。研究结果表明该传感器对葡萄糖在3.0×10-6～4.98×10-4mol/L范围内呈良好的线性响应,灵敏度为1.03×10-3A.L/mol。     

Ni-Cu/Al_2O_3催化剂上顺酐液相选择加氢制丁二酸酐反应性能

以Al2O3为载体,采用等体积浸渍法制备了一系列Ni-Cu/Al2O3催化剂,用于顺酐液相加氢反应,并结合低温N2物理吸-脱附、H2程序升温还原、H2程序升温脱附、X射线衍射、CO程序升温表面反应等表征结果,详细考察了催化剂中Cu含量对其催化性能的影响.结果表明,Cu的引入提高了活性组分Ni的分散度,促进了催化剂上C=C的加氢活性;同时,由于Ni-Cu双金属间的相互作用,明显抑制了催化剂表面C=O的加氢.当Cu含量为7%时,催化剂上顺酐加氢定向合成丁二酸酐的活性最高.在210oC,H2压力5.0MPa的条件下反应40min时,顺酐转化率与丁二酸酐选择性均达100%.     

A study of GaN MOSFETs with atomic-layer-deposited Al2O3 as the gate dielectric

Accumulation-type GaN metal-oxide-semiconductor field-effect transistors (MOSFETs) with atomic-layer-deposited Al₂O₃ gate dielectrics are fabricated. The device, with atomic-layer-deposited Al₂O₃ as the gate dielectric, presents a drain current of 260 mA/mm and a broad maximum transconductance of 34 mS/mm, which are better than those reported previously with Al₂O₃ as the gate dielectric. Furthermore, the device shows negligible current collapse in a wide range of bias voltages, owing to the effective passivation of the GaN surface by the Al₂O₃ film. The gate drain breakdown voltage is found to be about 59.5 V, and in addition the channel mobility of the n-GaN layer is about 380 cm²/Vs, which is consistent with the Hall result, and it is not degraded by atomic-layer-deposition Al₂O₃ growth and device fabrication.     

Synthesis and Characterization of Some Unique Heterocyclic Derivatives Containing Aluminium(III) Atoms in 4- and 6-Co-Ordination States∶ Reaction of Bis(β-Diketonato) Aluminium (III)-DI-μ-Isopropoxo-DI-Isopropoxo Aluminium(III) with Triphenylsilanol and Diphenylsilanediol

Reactions of bis ( g -diketonato) aluminium(III)-di- w -isopropoxo-di-isopropoxo-aluminium (III), [CH₃COCHCOR)2Al( w -OPrⁱ)₂Al(OPrⁱ) ₂], with triphenylsilanol, Ph₃SiOH, in 1:1 and 1:2 molar ratios and with diphenylsilanediol, Ph₂Si(OH)₂, in a 1:1 molar ratio, have resulted in the synthesis of [(CH₃COCHCOR)₂Al( w -OPrⁱ)₂Al(OSiPh₃)(OPrⁱ)], [(CH₃COCHCOR)₂Al( w -OPrⁱ)₂Al(OSiPh₃)₂] and [(CH₃COCHCOR)₂Al( w -OPrⁱ)₂Al(OSiPh₂O], respectively. These are soluble in a variety of organic solvents ( e.g. , benzene, chloroform and dimethylsulfoxide) and show dinuclear behaviour in chloroform. These derivatives have been characterized by elemental analyses, molecular weight measurements, IR and NMR (¹H, ¹³C and ²⁷Al) studies.     

Homo- and hetero-dinuclear derivatives of aluminium containing Schiff-base ligands: synthesis,characterization and antibacterial activity of mononuclear derivative of aluminium

Reactions of Al(OPrⁱ)₃ with LH₂ =?[R′C(NYOH)CHC(R)OH] R=R′=CH₃, Y =?(CH₂)₂ (L¹H₂); R =?CH₃, R′ =?C₆H₅, Y =?(CH₂)₂ (L²H₂); R =?R′ =?CH₃, Y =?(CH₂)₃ (L³H₂); R =?CH₃, R′ =?C₆H₅, Y =?(CH₂)₃ (L⁴H₂), in 1 : 2 molar ratio give mononuclear derivatives of aluminium AlLLH (1a–1d). Equimolar reactions of AlLLH with M(OPrⁱ)₃ (M =?Al and B) yield homo- and hetero-dinuclear derivatives AlLLM(OPrⁱ)₂ (M=Al=2a–2d M=B=3a–3d). Reaction of 2a with L¹H₂ affords AlL¹L¹AlL¹ (4). All these derivatives have been characterized by elemental analysis, molecular weight measurements and plausible structures have been suggested on the basis of IR, NMR [¹H, ¹³C, ²⁷Al and ¹¹B] spectral data and FAB-mass studies of 2b and 3b. Schiff base L¹H₂ and its mononuclear derivative with aluminium (AlL¹L¹H) have been screened for their antibacterial activity against Escherischia coli and Bacillus subtilis.     

Design of aluminium boom and arm for an excavator

The aim of this work is to study the boom and the arm of an excavator in order to replace the material, which they are usually made of, with another material. In particular, the study wants to substitute the steel alloy for an aluminium alloy. This change lightens the components of the arm, allows to increase the load capacity of the bucket and so it is possible to increase the excavator productivity per hour.For this purpose many different load conditions have been studied numerically on the original excavator in order to estimate a safety factor and the deformability or flexibility of each component. These parameters have been used in order to design a new arm.The excavator which has been analyzed is composed of three elements and the load conditions assumed, in order to evaluate the stress, are five (lifting at the maximum and minimum distance from the axis of rotation, maximum load induced by hydraulic cylinders, spin of the arm of the excavator and collision with an obstacle, etc.).As regards to the safety factor and deformability in order to maintain the original value the new geometry of the arm involves an increase of the dimension and so the lightness is not correlate only to the variation of the material density.The weight of the final geometry of the aluminium arm is 1080 kg whereas the one of the steel arm is 2050 kg and consequently it has been possible to increase the capacity of bucket from 1 m³ to the 1.35 m³.With reference to the manufacturing cycle of the aluminium arm with the new pins, the price increased about € 2.500-3.000 and this aspect could be justified if we consider that the productivity per hour increased about 35%.