Al Components Research Articles

Metakaolin-Based Geopolymers for Targeted Adsorbents to Heavy Metal Ion Separation

Geopolymer adsorbents were prepared from silica and metakaolin in different Al and Si components and applied for removal of metal ions, Cs+ and Pb2+, from other heavy metal ions mixture. The geopolymer was optimized at Si/Al = 2 as adsorbent, targeting to Cs+ and Pb2+ separation. The binding behavior was well fitted to Langmuir model, which proved that the metakaolin-based geopolymer had multibinding to adsorb ions. The effective adsorption was also observed independent of NaCl concentration for the Cs+ and Pb2+. This meant that the ion adsorption of geopolymers occurred under non-electrostatic mechanism.

OS1501 エレクトロマイグレーションによる微細材料大量創製へ向けたサンプル構造改良に関する研究

Micro-materials attract attention with their remarkable properties, including mechanical, thermal, electrical attribute. Various techniques have been developed for fabricating micro-materials. The fabrication technique by utilizing electromigration (EM), which is the physical phenomenon of atomic diffusion in a metallic line with a high-density electron flow, is one of the fabrication methods for generating micro-materials. EM technique can generate micro-materials with a high-aspect ratio, pure Al components, an arbitrary form, and a single-crystal structure. Whereas EM has significantly advantages, multiple micro-materials are difficult to fabricate simultaneously. The technique using conductive passivation and comb pattern has been recently developed for fabricating multiple micro-materials by the authors. The present study demonstrates the multiple fabrication more than previous research, and provides the approach for improving fabrication of multiple micro-materials by EM.

Higher Adherence to a Diet Score Based on American Heart Association Recommendations Is Associated with Lower Odds of Allostatic Load and Metabolic Syndrome in Puerto Rican Adults

A score based on diet and lifestyle recommendations from the AHA has been associated with cardiovascular risk factors. We aimed to assess whether the diet components alone were associated with metabolic syndrome (MetS) and allostatic load (AL; a composite measure of 10 physiologically dysregulated variables). The diet score ranged from 0 to 90 and included intake components for dietary fats, fruits and vegetables, whole grains, salt, added sugars, and alcohol and was tested in a cross-sectional analysis of 1318 Puerto Rican adults (aged 45–75 y; 72% women) living in Boston, MA. The mean ± SD diet score was 28.0 ± 9.9 for men and 30.0 ± 10.1 for women. Replicating findings from a previous study in this cohort that used both the diet and lifestyle components, we observed associations between the diet-only score and insulin, waist circumference, and HDL cholesterol. We found novel significant associations between the continuous diet score and AL components, namely an inverse association with urinary cortisol and a positive association with serum dehydroepiandrosterone sulfate in women as well as an inverse association with urinary norepinephrine in men (all P < 0.05). In multinomial logistic regression, every 10 AHA diet score units were associated with 22% (95% CI: 1, 38; P = 0.043) lower odds of having ≥6 (vs. ≤2) dysregulated AL components in women. In men, every 10 diet score units were associated with lower odds of MetS (OR: 0.69; 95% CI: 0.52, 0.93; P = 0.016). Following AHA recommendations for a healthy diet may protect against the development of components of MetS and AL in Puerto Rican adults.

Phase transition characteristics of Al-Sb phase change materials for phase change memory application

The crystallization behavior of Al-Sb thin films is investigated for phase change memory application. The crystallization temperature and optical band gap of the amorphous material increase with Al content. The thermal stability and randomness in atomic configuration of the films are enhanced considerably. The shift of Raman modes associated mainly with Sb upon phase transformation is observed, and the co-existence of Sb-rich crystalline regions and Al-rich amorphous matrix is confirmed, revealing the amorphous nature of most Al components. Three distinct resistance levels are achieved in the devices using Al50Sb50, suggesting the potentiality for multilevel data storage application of the materials.

Effect of Al components on the properties of CuAlO2 thin films deposited by RF magnetron sputtering

CuAlO2 (CAO) thin films with Al volume fraction of 1–5% were prepared by RF magnetron sputtering and were annealed at 1173K for 4h in the air. The microstructures, optical and hydrophily properties of the as-deposited films were studied. XRD measurement shows that all films are polycrystalline and present as Cu–Al–O phase. 3D profilometer measurement shows the minimum of surface roughness is 11.6nm for 1%Al–CAO film, and the maximum is 38.6nm for 5%Al–CAO film. The transmittance in the visible range decreases from 60% to 40% after the annealing process as a result of impurity and rough surface. The minimum value of average refractive index and extinction coefficient is about 1.41 and 0.031 for 1%Al–CAO film. The estimated direct band gaps of CAO films are 3.37–3.53eV. CAO films changes from hydrophobicity to hydrophily after annealing, and water contact angle of the annealed film increases from 31.1° to 70.5°.

The mechanical properties of fly ash-based geopolymer concrete with alkaline activators

As part of the research effort to develop cementless alkali-activated concrete using 100% fly ash as a binder, this paper aims to examine the effects of chemical changes of alkaline activators on the compressive strength of mortar and to analyze the microstructure of the mortar through SEM, EDS, XRD, FT-IR and by porosity assessments. The results showed that chemical changes of the alkaline activators had a significant effect on the early strength with higher molarity. In addition, the analysis of the structure through SEM and EDS indicated that the components having a considerable influence on the structure of the mortar were the Al and Si components. The XRD results revealed that there were no practical differences in the intensity according to the differences in the chemical components of the alkaline activators. On the other hand, the FT-IR analysis made it possible to identify changes in the chemical combination of SiOSi and SiOAl compared to fly ash and hardened mortar. The analysis of the porosity enabled us to verify indirectly the remarkable mechanical performance which was obtained by the activation of polymerization according to the chemical components of the alkaline activators. A relationship between the compressive strength and the splitting tensile strength of fly ash-based geopolymer concrete is proposed.

Asymmetric accumulative roll bonding of aluminium–titanium composite sheets

Aluminium–titanium (Al/Ti) composite sheets were fabricated via asymmetric accumulative roll bonding (AARB), which capitalises on additional shear to enhance plastic deformation. Multi-layers of Al alloy (AA1050) and commercially-pure Ti sheets were alternatively stacked and rolled-bonded with varied roll diameter ratios (dr) ranging from 1 to 2, for up to four passes. Annealing of selected composite sheets was subsequently carried out at 600°C for 24h to compare the rates of solid-state diffusion reactions between Al and Ti components. Mechanical tests revealed that both tensile strength and ductility of the sheets increase systematically with dr. The microstructures and the Al/Ti interfaces of the sheets were analysed in detail using TEM, SEM and FIB techniques. It is shown that not only does AARB lead to a more refined grain size of the Al matrix but also it promotes the development of a nanostructured surface layer on Ti that comprises crystallites of 50–100nm in size, which is otherwise absent in the case of symmetric ARB (i.e. dr=1). The AARB-processed sheets exhibit a larger thickness of the interdiffusion layer at the Al/Ti interfaces than the counterparts processed via the symmetric ARB route, the difference being in excess of 15%. The effects and the implications of AARB processing on mechanical behaviour and diffusion kinetics are discussed with respect to the microstructural evolutions.

Behavior of Heavy Metals during the Agro-Industrial Wastes Gasification

The characterization analysis of three agro-industrial wastes was performed in order to study its thermal gasification. Some analyses such as determination of Ca, K and Mg concentration and determination of three representative toxic metals concentration Cd, Cr and Pb in all its oxidation states and the fundamental state, were carried out. The heavy metals concentration was also determined in the ashes obtained during the gasification process. The mobility of these elements was studied through three leaching tests. The behavior of heavy metals, sulfur and chlorine compounds, was predicted considering the presence of water vapor, syngas, Ca, Mg, K, Si, Al and other ash components. The heavy metals are not more concentrated in the gasification ash; these pollutants are released during this process. Ca, Mg and K presence in these residues would promote the pollutants retention. The ash of the studied waste can be disposed in controlled landfills or used in road construction, according to the obtained results during the leaching test DIN-DEV S4. The obtained results in the leaching test EPA 1311 TLCP classify these gasification ashes as no toxic waste.

Liquidus surface and melting diagram of the Al–Ti–Pd system in the Al–AlPd–TiPd–Ti region

The solidification of Al–Ti–Pd alloys is studied by light optical and scanning electron microcopy, electron microprobe analysis, X-ray diffraction, and differential thermal analysis in the composition range 0–50 at.% Pd in the Al–AlPd–TiPd–Ti partial system. The liquidus surface projection, melting diagram, and Scheil diagram are constructed for the first time. Eleven regions of primary solidification of ternary compounds, solid solutions based on binary phases, and Ti and Al components are found to exist. The τ3 phase melts congruently while τ1 is formed incongruently. Eleven four-phase invariant equilibria involving a liquid phase exist in the system: two of them are congruent and nine incongruent. The invariant four-phase reactions occur in the temperature range between 630 and 1425–1456°C.

Transport And Surface Properties Of Molten Al-Mn Alloy

The concentration fluctuation in long wavelength limit (SCC(0)) has been computed from experimental data of chemical activity of pure Al and Mn components in molten Al-Mn alloys at 1600K. The SCC(0) is used to obtain Warren-Cowely short range order parameter (α1) and ratio of mutual and intrinsic diffusion coefficients (DM/Did) for this alloy. The surface concentration of pure components with respect to corresponding bulk concentration of pure components for Al-Mn alloy at 1600K has been computed on the basis of Butler’s approach. These surface concentrations are then used to calculate the surface tension for this system.

The influence of cation additives on the NIR luminescence intensity of Er3+-doped borate glasses

Er3+-doped 25BaO-(25-x)SiO2-xAl2O3-25B2O3 transparent glasses are prepared with x = 0, 12.5 and 25 by a solid-state reaction. The Er-related NIR luminescence intensity, which corresponds to the transition of 4I15/2-4I13/2, is obviously altered with different silicon/aluminum ratios. The Judd-Ofelt parameters of the Er3+ ions are adopted to explain the intensity change in the NIR fluorescence, and the Raman scattering intensity versus the amount of Al and/or Si components are discussed. The spectra of the three samples are quite similar in the peak positions, but different in intensity. The maximal phonon density of state for the samples is calculated from the Raman spectra and is correlated to the NIR luminescence efficiency.

Recovering Obliterated Engraved Vehicle Identification Number on Vehicle Frame Surfaces by Etching Technique

Chemical etching, which is the most sensitive method to recover obliterated serial numbers on metal surfaces. This paper studied the method of recovering obliterated engraved vehicle identification number on vehicle frame surfaces by etching technique. Experiment research indicates that for vehicle frame materials containing Al and Si components, the use of concentrated hydrochloric acid : acetic acid : ethanol=2:1:1( volume ratio) reagent shows good effectiveness; For vehicle frame materials Mn and Si composition, the use of concentrated nitric acid: acetic acid: ethanol=1:1:1 ( volume ratio) shows good effectiveness. This recovering method has far-reaching application prospects, especially in the robbery cases involving vehicle identification numbers juggled.

Mechanochemical synthesis and compaction of intermetallic alloys containing nanocrystalline substructure elements

The peculiarities of phase formation during mechanochemical treatment of mixtures containing elementary Ni and Al components in an atomic ratio of 3: 1 and graphite in various amounts are considered. As a result of mechanochemical treatment, supersaturated solid Ni(Al, C) fcc solutions form, in which the content of carbon reaches 0.5–0.6 atom/unit cell. When perovskite carbide, Ni3AlC x , is in the equilibrium ordered state, the amount of carbon is x ≤ 0.3 atom/unit cell. Ni(Al, C) solid solutions obtained by mechanochemical synthesis are compacted by hot isostatic pressing (HIP) and are found to lead to the formation of a microstructure in which micrograins (2–5 μm) of ordered Ni3AlC x phase are surrounded by nanoscale graphite particles (<50 nm). In order to bind the graphite released during heating, carbide-forming elements (i.e., Nb, Ti, and Hf) are added to a mechanochemically synthesized Ni(Al, C) solution. Subsequent short-term mechanochemical activation of these mixtures results in homogeneous distribution of carbide-forming elements without carbides being formed. After compaction by means of HIP, solid solutions undergo ordering, and excess carbon forms nanocarbides at the grain boundaries.

Two-dimensional hole gas in p-GaN/p-AlxGa1-xN heterojunctions and its influence on Ohmic contact

In this paper, the characteristics of the two-dimensional hole gas (2DHG) in p-GaN/p-AlxGa1-xN heterojunction is investigated in detail, based on self-consistent solutions of one-dimensional Poisson and Schrdinger equations. The valence band structures and the 2DHG distributions are calculated in the cases of different Al components and piezoelectric polarization effects. Then, the influences of Al components and piezoelectric polarization effects on 2DHG are analysed specifically. The results show that with the increase of Al component, the quantum well at the heterojunction interface turns deeper and narrower, which leads to an accelerated growth of the 2DHG peak density and a line increase of the 2DHG sheet concentration. Furthermore, piezoelectric polarization effects also make the quantum well at the heterojunction interface deeper and narrower, at the same time, the Fermi level moves close to the top of the barrier and the location of peak density moves close to the heterojunction interface. In addition, the influences of valence band offset and acceptor doping concentration on 2DHG are relatively small. Ohmic contact of p-AlxGa1-xN is fabricatea with the 2DHG, and its I-V characteristic is much better than that without the 2DHG, which indicates that the 2DHG can significantly improve the performance of p-AlxGa1-xN ohmic contact.

Friction stir processing of aluminum cast alloys for high performance applications

Friction stir processing (FSP) is a novel process developed based on the principle of friction stir welding (FSW) that locally manipulates the microstructure by imparting a high level of energy in the solid state resulting in improved mechanical properties. Additionally, FSP has emerged as an advanced tool to produce surface composites by embedding second phase particles into the matrix. Our work to date has shown that FSP can be implemented as a post-casting method to locally eliminate casting defects, such as porosity due to gas evolution during casting. Coarse second phases are broken up into fine nearly equiaxed particles and distributed uniformly in the matrix; grain refinement is also attained by dynamic recrystallization during FSP. This results in improved mechanical properties. Furthermore, our work shows that friction stir processing is a viable means of producing localized composite zones in cast Al components. Such improvements have important implications for manufactured components for diesel engines and for critical and high integrity components. The convenience of FSP as a post-processing step that can easily be carried out during machining operation makes it quite attractive for adoption.

Numerical Simulation of 3-D Chemical Non-Equilibrium Flow in the Afterburning Chamber of Solid Ducked Rocket

In order to reveal the complex turbulent combustion processes in the afterburning chamber of Solid Ducked Rocket (SDR), Based on the fundamental equations of hydrokinetics and elementary principles of radical reaction kinetics, using multi-component chemical reaction equation of containing Mg and Al components, the numerical simulation of chemical non-equilibrium flow in the afterburning chamber of SDR is processed and effects of the air inlet angle on the afterburning chamber is studied by using Fluent software. The results show that pressure distribution is more balanced, temperature distribution is very uneven and flow is extremely complicated in the afterburning chamber. Combustion efficiency can be increased by improving the air inlet angle.

Composites Fabrication via Friction Stir Processing

Friction stir processing (FSP) is a post-processing method that locally manipulates the microstructure by imparting a high level of energy in the solid state giving rise to improved mechanical properties. Additionally, FSP has emerged as an advanced tool to produce surface composites and synthesize the second phase into the matrix. In the current study, FSP was investigated for the manufacture of localized zones of composite materials made by the emplacement of a second phase into cast A206 Al alloy matrix. Both the discontinuously reinforced aluminum (DRA) and some encapsulated powders (nano-sized SiC or Ta) were used for the second phase emplacement. Through SEM and EDS mapping, the morphology and distribution of second phase particles have been studied. The work shows that friction stir processing is a viable means of producing localized composite zones in Al components.

Preparation of mullite fibres by sol–gel processes using aluminium carboxylates and tetraethylorthosilicate

Mullite fibres were prepared using aluminium carboxylates (ACs) and tetraethylorthosilicate by sol–gel process. ACs were synthesised from dissolution aluminium in a mixture of formic acid and glacial acetic acid using aluminium chloride hexahydrate as catalyst. The optimum condition for obtaining ACs is as follows: the molar ratio of aluminium, formic acid and acetic acid was 1∶3∶2·26 and aluminium chloride hexahydrate was 10 wt-%. All the Al and Si components were mixed at the molecular level and linear molecules were formed in the precursor sol. The dried gel fibres completely transformed to mullite fibres at 1200°C and the calcinated fibres had a smooth surface and uniform diameter.

Characteristics of Fe-Cr-Al Alloy Nanopowders Prepared by Electrical Wire Explosion Process under Liquid Media

Fe-Cr-Al alloy nanopowders were successfully prepared by electrical wire explosion method in ethyl alcohol media. The formation of Fe-Cr-Al alloy nanopowder was monitored by X-ray diffraction. The alloy powders have spherical shape and nanometer size. The alloy powders prepared by the electrical wire explosion method have main crystal structures of bcc Fe-Cr alloy. The geometric mean diameter and geometric standard deviation of an alloy powder formed from a wire with diameter of 0.1 mm were 10.2 nm and 1.62, respectively. However, the geometric mean diameter and geometric standard deviation of an alloy powder formed from a wire with diameter of 0.2 mm were 15.4 nm and 1.66, respectively. These values indicate that the particle size of the alloy powders prepared by the EWE method was increased with wire diameter. Fe, Cr, and Al components are uniformly dispersed inside the powder.

Optimized growth of p-type AlGaN electron blocking layer in the GaN-based LED

In the High-power InGaN/GaN-based LED structures, p-AlGaN layer plays a role as electron blocking layer. In this paper, GaN/InGaN-based LED have been grown on sapphire by metal organic chemical vapor deposition (MOCVD), and the p-type doping mechanism and structural optimization of AlGaN layer were studied. The ways to change AlGaN components have been discussed. We found that the growth temperature, growth pressure and flow TMAl (mole ratio) have strong effect on the Al components through different mechanisms. In the AlGaN electron blocking layer, the Al composition is between 10%—30% and the electron could be well limited to the quantum well region, maintaining a high quality crystal material. The p-type doping efficiency of AlGaN layer is low, and there is a magnesium droop problem due to lack of hole injection. A new growth method is suggestece to solve the problem. Grown under optimal conditions, the p-type AlGaN inserted in a LED structure greatly improves the output optical power of LED device.