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Towards the Design of Highly Heterogeneous Aluminum Alloys
(2025-01-01)
Eskin, Dmitry G.
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Chankitmunkong, Suwaree
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Zhu, Chengbo
Modern engineering applications require new types of alloys with a unique combination of properties. Alloys with the large volume fraction of intermetallic phases started to attract the attention of researchers, for example, eutectic alloys of the Al–Fe–Ni and Al–Ce–Ni systems. Such alloys have high elasticity modulus, thermal stability, hardness and high-temperature properties, however their applications is limited to casting and mostly hypoeutectic or eutectic alloys. Formation of primary intermetallics poses a challenge unless they can be efficiently refined. Here we present a number of approaches to refine the structure of hypereutectic Al Fe, Al–Ni, Al–Ce–Ni–Mn alloys through additions, ultrasonic processing (USP) and increased cooling rates. As a result, the structure of alloys makes them suitable for deformation and additive manufacturing with extra strength gained through dispersion hardening. These approaches may pave way to the new type of alloys for demanding applications.
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Effects of Zinc and Aluminum on the CuO Crystalline Size for Direct Dimethyl Ether Synthesis from Syngas
(2021-09-01)
Thongkam, Montree
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Piyabunditgul, Nanchapak
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Trisupakitti, Somsuk
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Rungrojchaipon, Pesak
The effects of zinc and aluminum on the CuO crystalline size for direct dimethyl ether (DME) synthesis from syngas were investigated. Metal oxide catalysts were synthesized with various molar ratios of CuO by the precipitation method, and by the co-precipitation method with CuO/ZnO (CZ), CuO/ZnO/Al<inf>2</inf>O<inf>3</inf> (CZA), and CZA at ratios of 1:1, 2:2:1, and 6:3:1, respectively. The acid catalysts (γ-Al<inf>2</inf>O<inf>3</inf>, HZSM-5) were added to the metal oxide catalysts by physical mixing. The catalysts were characterized morphologically and their acidities were determined. Loading of zinc and aluminum at different ratios showed that CZA (2:2:1) gave the smallest CuO crystalline size, appropriate for the methanol synthesis reaction. γ-Al<inf>2</inf>O<inf>3</inf> has a weak to moderate acidity range, suitable for DME synthesis. Moreover, the bifunctional catalyst, CZA (2:2:1)/γ-Al<inf>2</inf>O<inf>3</inf>, had the highest surface area as well as the highest %CO conversion and %DME selectivity.
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Effects of carbon doping and annealing temperature on magnetic MnAl powders and MnAl polymeric composites
(2021-03-01)
Thongsamrit, Wannisa
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Charoensuk, Thanida
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Saetang, Panissa
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Jantaratana, Pongsakorn
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Ruttanapun, Chesta
Process parameters leading to magnetic polymer composites, an essential ingredient in the additive manufacturing of rare-earth-free magnets, are investigated. The induction melting of manganese (Mn) and aluminum (Al), and subsequent annealing at 450, 500, or 550 °C for 20 min, gave rise to ferromagnetic τ-MnAl phase, as well as other phases. The nonmagnetic Al<inf>4</inf>C<inf>3</inf> and oxide phases were then removed by the magnetic separation. Magnetic powders from the magnetic separation were incorporated in polylactic acid (PLA) matrix via a solution route. The remanent magnetization as high as 4.3 emu/g in the powder form was reduced to 2.3-2.6 emu/g in the composites. The reduction in coercivity was minimal, and the largest value of 814 Oe was obtained when the powder annealed at 450 °C was loaded in the composite. The phase composition and hence magnetic properties were even more sensitive to the carbon (C) doping. Interestingly, the addition of 3% C led to coercivity as high as 1445 Oe in MnAl-C powders without further annealing. The enhanced coercivity was attributed to the domain wall pinning by the AlMn<inf>3</inf>C phase, and magnetizations are likely increased by this phase.
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Robot arm structure design using polyamide evaluated by finite element analysis
(2020-01-01)
Kaitwanidvilai, Somyot
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Buthgate, Siwawong
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Aoyama, Hisayuki
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Konghuayrob, Poom
Robots have increasingly replaced humans for many jobs, including 24 h work, routine tasks, and dangerous jobs. However, the robot operating system has high power consumption in many processes. This has led to energy efficiency being the main focus. We have opted to build a robot with high strength, light weight, and low power consumption by reducing the weight of its components. Presently, we know that the structure of most robots in the world is made of metals, plastics, and composite materials. In this research, we designed the mechanical structure of robot arms with three different materials (cast iron, polyamide, and aluminum) using the finite element method to analyze and evaluate the possibilities of these materials. The dynamic load, power consumption, and mechanical characteristics were compared. It was found that polyamide could help lighten the weight by 40% and increase energy efficiency along with cost effectiveness by 41%. Although polyamide is particularly easy to find, cast iron is stronger than polyamide.
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UV photodetector based on al-doped zno nanocrystalline sol-gel derived thin fims
(2014-01-01)
Chongsri, K.
;
Pecharapa, W.
Aluminum doped zinc oxide (AZO) thin films were studied as an UV photodetector devices. The AZO thin films were prepared on FTO substrates by spin coating technique. All samples exhibit prominent optical absorption edge with high optical transparency in visible range and significant blue-shift in optical band gap with increasing Al composition. The photoilluminated current increases linearly with increasing bias voltage reflecting ohmic contact behavior. The detectors have excellent ultraviolet response in wavelength region of 250-380 nm suggesting that tunable wavelength response can be obtained by increasing Al composition.

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