EMI Suppression Characteristics of Pure and Impure Ni-Zn Ferrities and Mg-Zn Ferrities

Electromagnetic Interference (EMI) is a wave pollution, which interrupts the functioning of electronic circuits. Therefore, EMI wave absorbing materials are needed to suppress the wave pollution. One of the best solutions to overcome this problem is by using ferrites as EMI suppressors. This work is hoped to give a better understanding on how the purity of constituent oxides affects the suppression capability of ferrites. Moreover. it is also hoped to contribute in understanding how a good EMI suppressor can be made. A total of 1 2 toroidal samples with the composition of NixZnl-xFe204 and another 12 toroidal samples with the composition M&tZnl-xFe204 were prepared via the conventional ceramic processing method, where x = 0.1 , 0. 15, 0.2, 0.25, 0.3, 0.35. These samples were prepared to be ferrites with purities -99.99% and -;!J9. 1% which denoted pure and impure ferrites respectively. Subsequently, these samples were sintered in air at 1300°C. The measured parameters to study the magnetic properties were density, permeability, relative loss factor, impedance, resistivity, microstructure and XRD analysis. It was found that the overall magnetic properties for pure Ni-Zn Ferrites and Mg-Zn Ferrites were only slightly better than those of impure Ni-Zn ferrites and Mg-Zn Ferrites; the parameter values did not differ very much. Therefore, it is more economic if the impure materials are used for ferrite production instead of pure materials, which are more expensive

Electrical, magnetoresistance and magnetotransport properties of Nd1−xSrxMnO3

The effects of Sr substitution on the electrical, magnetoresistance and magnetotransport properties of Nd1−xSrxMnO3 were studied. Nd1−xSrxMnO3 samples were prepared using the solid-state reaction method with x=0.12, 0.152, 0.22, 0.252 and 0.32. All samples showed an orthorhombic structure, and no impurities were detected when the samples were examined using the X-ray diffraction method. The grain size was between 10 μm and 16 μm for all samples. The sample with x=0.32 showed the smallest grain size and the lowest To value, where To reflects the MnOMn bond angle. As the Sr concentration increased, the grains grew into more pentagonal and hexagonal shapes, and the insulator–metal transition temperature, Tim, also increased from 131 K to 180 K. The exceptions were the samples with x=0.152 and 0.252, where charge ordering was found at 120 K. The samples with the most pentagonal and hexagonal shaped grains (x=0.32) had the highest Tim. The magnetoresistance (MR) values were found to increase with increasing magnetic field. The sample with x=0.32 showed the highest MR value (31.5%), the highest Tim, the smallest grain size (∼10 μm) and the least bending of the MnOMn bonding angle

Sound-absorbing material based oil palm frond natural fibres

Effective noise control is vital for improving living standards, but traditional sound absorbers pose health risks. Natural fibers offer a sustainable alternative, with consistent absorption rates across a broad frequency range. These fibers, widely available in Malaysia, are non-toxic, lightweight, renewable, and eco-friendly, making them an attractive option. The safety benefits of natural fibers further enhance their appeal as sound absorbers, making them an excellent choice for those concerned about environmental impact and personal health. This study will examine the effect of different thicknesses on the acoustic performance of natural fibers from oil palm fronds (OPF). The findings demonstrate that, when material density is 160 kg/m3 , all thicknesses can achieve a good Sound Absorption Coefficient (SAC) of 0.8 or greater within 3600 - 6400 Hz range. However, at 180 kg/m3 density, only the 10 mm thickness sample has SAC of 0.8 or greater, but for 2800 - 6400 Hz range. It is worth noting that, across 0 - 6400 Hz, 10 mm thick and 180 kg/m3 density sample has higher SAC than 160 kg/m3 samples. Nevertheless, for 12 mm, 14 mm, and 16 mm thicknesses, SAC of 160 kg/m3 is higher than 180 kg/m3 after an interception point. Before that interception point, SAC of 160 kg/m3 is lower than 180 kg/m3 . As thickness increases from 12 mm to 16 mm, the interception point decreases from 2100 Hz to 1600 Hz. The research demonstrates that various factors, such as frequency, density, thickness, and fiber structure, impact the acoustic performance of OPF LDF

Synthesis and characterization of red pigment from acid regeneration plant (ARP) by-product via rod milling process

Iron o xide waste from acid regeneration plants (ARP) is often discarded due to its non-profitability. This research aims to introduce a value-added process to convert iron oxide waste into red pigment via rod milling process. The iron oxide waste collected from ARP was grinded with a rod milling machine at 30 rpm for 24 hours. The ground product was then mixed with industrial-grade red pigment in various ratios. The mixed samples were then rod-milled again into ultra-fine particles. A total of seven samples were prepared, applied onto a canvas and analysed by energy dispersive X-ray spectroscopy (EDX) and X-ray diffraction (XRD) methods. From the analyses, the existence, composition, and orientation of iron oxide were established. The waste-derived red pigments were subsequently subjected to particle size analysis on a scanning electron microscopy (SEM) platform, with results showcasing the efficiency of the rod milling process. Colour-related properties of the samples before and after canvas application were investigated using the L*a*b* system with a chromameter. Empirical outcomes indicated that the a* value plays an important role in determining the redness of the sample. Overall, the a* values obtained were above 15 and gradually increased in accordance to the amount of industrial-grade red pigment added. The oil absorptivity of red pigments was also tested via an oil absorptivity test. Notably, the assay signified that particle size and porosity affect the amount of oil that can be absorbed by the pigment

Magnetotransport properties of La0.67Ca0.33MnO3 with different grain sizes

The magnetotransport and magnetoresistive (MR)properties of manganese-based La0.67Ca0.33MnO3 perovskite with different grain sizes are reported. The electrical resistivity was measured as a function of temperature in magnetic fields of 0.5 and 1 T. The insulator–metal transition temperature, TIM, shifted to a higher temperature with the application of the magnetic field. In zero field, TIM is almost constant (∼271 K) for all samples except for the sample with the largest grain size, where TIM = 265 K. The temperature dependence of resistivity was fitted with several equations in the metallic (ferromagnetic) region and the insulating (paramagnetic) region. The density of states at the Fermi level, N(EF), and the activation energy of electron hopping were estimated by fitting the resistivity versus temperature curves. The ρ–T 2 curves are nearly linear in the metallic regime, but the ρ–T 2.5 curves exhibit a deviation from linearity. The variable range hopping model and small polaron hopping model fit the data well in the high-temperature region,indicating the existence of the Jahn–Teller distortion that localizes the charge carriers. MR was found to increase with an increase in the magnetic field, an effect which is attributed to the intergrain spin tunneling effect

The Effect of Friction Stir Welding Parameters on the Weldability of Aluminum Alloys with Similar and Dissimilar Metals: Review

The solid-state welding method known as friction stir welding (FSW) bonds two metallic work parts, whether the same or different, by plastically deforming the base metal. The frictional resistance between both metallic workpieces causes them to produce heat, which produces plastic deformation and welds them. However, the weldability and strength of FSW joints mainly depend on the FSW parameters. This review work highlights the previous research work on the FSW parameters and their effects on the weldability and quality of the aluminum alloys joined with similar and dissimilar metals through the FSW method. About 150 research studies were systematically reviewed, and the articles included data from peer-reviewed journals. It has been concluded that the key parameters, including welding speed, “rotational speed”, “plunge depth”, “spindle torque”, “shoulder design”, “base material”, “pin profile” and “tool type”, significantly affect the weldability of the aluminum joint through the FSW method. Also, the selection of these parameters is important and fundamental as they directly affect the joint. It is recommended that future work focuses on FSW for aluminum. Among these, the most essential is the application of artificial intelligence (AI) techniques to select the optimum FSW parameters for aluminum welding

The Effect of Friction Stir Welding Parameters on the Weldability of Aluminum Alloys with Similar and Dissimilar Metals: Review

The solid-state welding method known as friction stir welding (FSW) bonds two metallic work parts, whether the same or different, by plastically deforming the base metal. The frictional resistance between both metallic workpieces causes them to produce heat, which produces plastic deformation and welds them. However, the weldability and strength of FSW joints mainly depend on the FSW parameters. This review work highlights the previous research work on the FSW parameters and their effects on the weldability and quality of the aluminum alloys joined with similar and dissimilar metals through the FSW method. About 150 research studies were systematically reviewed, and the articles included data from peer-reviewed journals. It has been concluded that the key parameters, including welding speed, “rotational speed”, “plunge depth”, “spindle torque”, “shoulder design”, “base material”, “pin profile” and “tool type”, significantly affect the weldability of the aluminum joint through the FSW method. Also, the selection of these parameters is important and fundamental as they directly affect the joint. It is recommended that future work focuses on FSW for aluminum. Among these, the most essential is the application of artificial intelligence (AI) techniques to select the optimum FSW parameters for aluminum welding