Control of Amount of α-Al Phase Particles in near Eutectic Al-Si Alloy by Electromagnetic Stirring

Al-Si alloy is widely used as a casting alloy. The α-Al phase in the semi-solid state has low Si content in the Al-Si alloy. Then by separation of these α-Al phases from semi-solid Al-Si alloy, refining of aluminum can be possible. But, in near eutectic Al-Si alloy, few primary α-Al phases can be crystallized. If the fraction ratio of the α-Al phase can be increased, near eutectic Al-Si alloy can refine, and this method can be used for recycling. In this study, the effect of electromagnetic stirring (EMS) on the microstructure, especially the amount of the α-Al phase particles was investigated. A rotational magnetic field was applied to JIS ADC12 alloy which has near eutectic content during slow cooling from the liquid state to the solid-state, by using a three-phase AC coil. By applying EMS at solidification, the shape of the α-Al phase became particle shape from dendrite shape, and the amount of α-Al phase particles was increased. Moreover, by applying unidirectional intermittent EMS, the volume fraction of α-Al phase particles was decreased with increasing intermittent applying time. In ADC12 alloy, the primary α-Al phases can be crystallized only 10% generally, but it could be obtained over 40% by applying EMS. This means that the semi-solid slurry of near eutectic alloy with over 40% of fraction solid can be obtained by applying EMS.

Development of αFe2O3-TiO2/PPOdm Mixed Matrix Membrane for CO2/CH4 Separation

Magnetophoretic dispersion of magnetic fillers has been proven to improve gas separation performances of mixed matrix membrane (MMM). However, the magnetic field induced is usually in a horizontal or vertical direction during membrane casting. Limited study has been conducted on the effects of rotational magnetic field direction towards dispersion of particles. Thus, this work focuses on the rearrangement of paramagnetic iron oxide-titanium dioxide (αFe2O3-TiO2) nanocomposite in poly (2,6-dimethyl-1,4-phenylene oxide) (PPOdm) membrane via rotational magnetic field to investigate the dispersion of filler and effects towards its overall gas separation performance. The paramagnetic fillers were incorporated into polymer via dry phase inversion method at different weight loading. MMM with 3 wt% loading shows the best performance in terms of particle dispersion and gas separation performance. It shows the greatest relative particles count and least agglomerates via OLYMPUS™ Stream software with image taken by optical microscope. Relative to pristine membrane, it displays a permeability and selectivity increment of 312% and 71%. MMM with 3 wt% loading was refabricated in the presence of rotational magnetic field to enhance the dispersion of paramagnetic fillers. Results display an increment of selectivity by 8% and CO2 permeability by 46% relative to unmagnetised MMM of 3 wt% loading.

Catalytic/magnetic assemblies of rolled-up tubular nanomembrane-based micromotors

Ti/FeNi/Pt tubular micromotors self-assemble into static and dynamic clusters during catalytic decomposition of hydrogen peroxide and using an external rotational magnetic field.