Papers by Keyword: Magnetic Material

Abstract: This paper presents an initial investigation into the numerical modeling of additive manufacturing processes for AlNiCo magnets. The research concentrated on calibrating the heat source parameters by utilizing previously published experimental results. The influence of laser power and scanning speed on the laser fusion of AlNiCo5 on SS 304 substrates was investigated through single track experiments. The geometries of the melt pools were measured and utilized as the foundation for model calibration. A two-step calibration methodology was adopted: (1) a simplified 2D model implemented in Octave was used for sensitivity analysis and parameter fitting; and (2) validation was performed using a 3D model within the commercial software Simufact Welding software. Parameters calibrated through 2D simulations could be directly transferred to the 3D context. However, while the calibration procedure enabled accurate fitting for individual tracks, it resulted in globally non-optimal parameters, suggesting that process parameters influence laser penetration depth.

Abstract: Ferrite is frequently employed as a high-efficiency microwave absorption material (MAM). Herein, a novel and prospective high-temperature mechanochemical (HTMC) method was employed to fabricate pure-phase spinel zinc ferrite powders with a spherical structure. After that, the chemical compositions and structures, microscopic morphology, static magnetic characteristics, and microwave absorption properties of the powders were examined. The powder achieves a minimum reflection loss of -54.7 dB at a matching thickness of 4.4 mm, at which time the effective absorption bandwidth approaches 3.9 GHz. The superior microwave absorption ability of the powders is attributable to the favorable cooperative impact between dielectric and magnetic losses. Therefore, the as-prepared zinc ferrite powders can be utilized as high-efficiency MAM. The HTMC method has considerable potential for the large-scale preparation of high-performance MAM.

Abstract: This study describes the sol-gel method's synthesis of ferrites [MFe₂O₄, M(II) = Co, Cu, Mg, Ni, and Zn]. The structure was studied by X-ray diffraction analysis. The surface morphology was studied using scanning electron microscopy (SEM), and the magnetic properties were studied using Mössbauer spectroscopy. The diffraction peaks at 30.1^◦, 35.6^◦, 43.2^◦, 53.6^◦, 57^◦, and 62.6◦ can be attributed to Bragg reflections (2 2 0), (3 1 1), (4 0 0), (4 2 2), (5 1 1), and (4 4 0) planes confirm the formation of a cubic spinel structure of ferrite nanocrystals. The average size of magnesium ferrite crystallites calculated from the half-width of the most intense peak (3 1 1) was 25.96 ± 4.32 nm. Magnesium ferrite is a magnetically soft ferromagnetic powder with a predominance of the magnetite phase and relatively high magnetisation values. The magnitude of the hyperfine magnetic field for the studied nanoparticles is in the range of 440-490 kOe, which confirms the hypothesis that the analysed samples are particles of an iron-containing oxide with a disordered structure.

Abstract: In this study, adsorption as an environmental friendly technique has been applied for separation and recovery of gold (Au) from gold mining rock sample with iron sand magnetic material coated with silica/chitosan (MMSC). The works included preparation and characterization of adsorbent; gold leaching from the rock sample, and adsorption-desorption of Au(III) in leaching solution and calculation of recovery. The result showed that the leaching solution contained Au(III), Cu(II) and Zn(II) of 0.14, 16.0, and 181 mg/g, respectively. Adsorbent investigated was selective for Au(III) against Cu(II) and Zn(II) ions with the selectivity coefficient, α_Au/Cu of 7.71±1.28 and α_Au/Zn of 29.48±15.11. The adsorption-desorption of metal ions in the rock sample solution obtained the recovery of 77.49±0.96, 0.21±0.00, and 0.04±0.01 % for Au(III), Cu(II), and Zn(II), respectively.

Abstract: An instrument based on electromagnetic induction method for detecting magnetic material in soil subsurface has been developed. The instrument consists of a signal generator, an amplifier, a transmitter, receivers, detectors and a display. A coil is used as transmitter. As receiver and also detector is used a three dimensional self-developed fluxgate sensor. The fluxgate sensor consists of two pick-up coils, four excitation coils, and a ferromagnetic core. The output voltage of the sensor is processed using an analog signal processing circuit. The sensor’s capability in detecting magnetic material in the soil subsurface was observed by placing a sample of magnetic material in the subsurface, and then detected using fluxgate sensor in the direction of the x, y and z (3D). We found that the developed instrument is capable to detect two different objects that is separated at minimum distance around 10 cm with the maximum shallow depth of the target material is 10 cm.

Abstract: Fluxgate sensor has high sensitivity and temperature stability, small size and low power consumption. Fluxgate sensors can often provide very useful alternative in determining the location or position of a magnetic object, where other technologies cannot be used. For example, the GPR only, does not provide maximum results when used to characterize the magnetic material in the conductive subsurface or has a high reflectivity zone, but fluxgate sensors are capable. Characterization of magnetic materials in the soil subsurface is required. It is used as a proxy to determine the content of heavy metals and pollutants in the soil. In this work, we have carried out the development of fluxgate sensors for detection of magnetic material in soil subsurface. The fluxgate element consists of two pick-up coils, four excitation coils, and the ferromagnetic core. The highest sensitivity of fluxgate sensors that have been developed is 877 mV/µT and a maximum absolute error of 0.066 mV/µT. This paper will discuss the influence of the frequency of the primary magnetic field of the solenoid on the sensor response, the influence of soil magnetic susceptibility, and the effect of the presence of magnetic material in the soil subsurface to the sensor response.

Abstract: Nanocrystalline/nanosized magnetite - Fe₃O₄ powder was obtained by mechanical milling of well crystallized magnetite obtained by ceramic method starting from stoichiometric mixture of commercial hematite - Fe₂O₃ and iron - Fe powders. The mean crystallites size of the magnetite is decreasing upon increasing the milling time down to 6 nm after 240 minutes of milling. After 30 minutes of milling an undesired hematite phase is formed in the material. The amount of this phase increases upon increasing the milling time. In the early stage of milling (up to 30 minutes) the existence of nanometric particles (mean size below 100 nm) is noticed. The d₅₀ median diameter decreases first (up to 5 minutes of milling) and after that, an increase follows for milling times up to 120 minutes. Saturation magnetization decreases upon increasing the milling time and is more difficult to saturate. X-ray diffraction, laser particle size analysis and magnetic measurements have been used for powder characterization.

Abstract: The effect of the mechanical alloying and nitriding time on the structure and properties of Sm-Fe-N alloys were studied in the course of the research. The influence of alloying elements (nitrogen, titanium, molybdenum) on the Curie temperature was investigated. It was revealed that the introduction of alloying elements leads to obtaining a homogeneous structure, an uniform distribution of particles, crystal lattice distortion and increasing the Curie temperature (up to 540-550 °C).

Abstract: Based on the magnetic materials (JV-5) substrate, Double L-shaped slot microstrip antenna is designed. The bandwidth is over 2 times that of the normal substrate and a 40% reduction in size happens.. On this basis, the microstrip antenna with magnetic substrate EBG structure is designed and the EBG structure uses the corrosive effects of joint floor, namely getting periodic H-shaped and circular structures by the floor corrosion, and performing a simulation with HFSS14.0. The results show that the EBG structure of magnetic material having a prominent advantage of the miniaturization and bandwidth-broaden compared to a microstrip antenna with non-magnetic materials substrate, resulting in more than 10% relative bandwidth and a slight gain loss. To some degree, introducing EBG structure can reduce the size of the antenna and increase its bandwidth, and it also improve the gain and radiation characteristics of the antenna.Key words: EBG structure; magnetic material;Double L-shaped slot microstrip antenna; gain

Abstract: Theoretical review on magnetic energy conception is still crucial since the recent discourse emerged in various conceptual speculations that lead into inconsistency in mathematical expression. The coming study should direct its formula into an interoperable equation which enables a magnetic energy to be observed as a mechanical work. The forthcoming expression of magnetic energy should represent operation of mechanical work definitely, considering the usage of Permanent Magnet (PM) in numerous mechanical devices. This interoperable magnetic-mechanical equation would be formulated from energy balance principle applied in both magnetic boundary and mechanical boundary. The energy balance assessment would clarify the usage of magnetic energy during the action of mechanical work. A computational study would assist this observation to interpret some magnetic parameters such as flux density B, magnetic strength H, magnetic energy E_m on a self-engineered device named Frequent Flux Collider which examines PMs to be attracted and repelled frequently. The research objectives are: 1) Presenting the technique for assessing the energy balance in PM; 2) Proposing an interoperable equation for bridging magnetic energy and mechanical work. In conclusion, the assessment has brought a theoretical hint to the development of interoperable magnetic-mechanical formula.