Papers by Keyword: Permanent Magnet

Abstract: Barium Hexaferrite is a permanent magnet material known for its excellent quality and relatively inexpensive manufacture. Barium hexaferrite has good stability and can be applied in various technologies. In this research, the synthesis of barium hexaferrite has been successfully made from the primary materials Fe (NO₃)₃ and Ba (NO₃)₂ using the sol-gel method, as well as other materials such as NaOH, chitosan, molasses, acetic acid and distilled water as the primary solvents for several materials. In addition, variations in aging time 0 hours, 2 hours, 4 hours and 6 hours were added to see the effect on morphology, crystal structure and the magnetic properties of barium hexaferrite magnets. The characterization process is carried out with three testing processes, namely X-Ray Diffraction testing (XRD), Scanning Electron Microscopy (SEM) and Vibrating Sample Magnetometer (VSM). From the XRD, it was found that the desired phase of Barium Hexaferrite (BaFe₁₂O₁₉) was formed, while in the SEM testing process, it was seen that the aging time of the barium hexaferrite sample decreased the particle size of the barium hexaferrite BaFe₁₂O₁₉ from an aging time of 0 hours seen 681.459 nm and at an aging time of 6 hours. Visible 538.859 nm particle size formed. The VSM characterization results showed that different aging times did not affect the barium hexaferrite nanomagnets' magnetic properties.

Abstract: The purpose of this study is to obtain a permanent magnet end-product from NdFeB and NdFeB / Co-Al composite material from SPS sintering which has high density with small grain size and strong corrosion resistance. NdFeB powder and NdFeB/Co-Al composites (0.2 and 0.5weight%) of several micron-sized particles resulting from the milling process have been successfully sintered with a temperature parameter of 800°C for 10 minutes and a pressure of 50MPa in dies with a diameter of 20 mm in a vacuum chamber. Optical micrographs show that the grains are uniformly and smoothly distributed throughout the surface. This is showing the types of grain distributions which has good mechanical properties. The X-ray analysis result shows the phase analysis confirms the presence of such main PM phases as Nd, Fe and B. From SEM observation, the particles have irregular shapes and a large particle size distribution. The density value of the sample is in the range of 7.1 - 7.3. From the density measurement it is also known that the sintering sample with SPS has a high-density level which is close to 100%, so it can be said that it has formed fully dense.

Abstract: Nd₂Fe₁₄B permanent magnet manufacturing technology in some developing countries is still relatively difficult because it is constrained by limited equipment facilities and dependence on imports of raw materials. In the context of efforts to build national independence, the concrete step is to try to study the process of making permanent Nd₂Fe₁₄B magnets with conventional facilities and technology. In this research an attempt was made to make and characterize Nd₂Fe₁₄B permanent magnets substituted with praseodymium Pr metal using conventional technology through the arc melting method. The success parameter of the results of this sample making is the formation of the Nd₂Fe₁₄B phase in the sample. The formation of this phase can be fundamentally studied the number of mass fractions of formed phases and structure crystallography using X-ray diffraction facilities and is supported by spectroscopy facilities and their magnetic properties. So the purpose of this research in general is to study the manufacturing process and the fundamental formation of the phases of the NdPrFe₁₄B sample making through the arc melting method, while specifically wanting to know the relationship between phase analysis and the magnetic anisotropic properties of NdPrFe₁₄B. The coercivity field appears to increase significantly after the sample is substituted with Pr and has a fairly small crystallite size distribution. So it was concluded that the presence of Pr was able to withstand the growth of grain, causing the anisotropic magnetocrystalline field to increase.

Abstract: During the test of DC(direct current) abrasive magnetic fluid technology,many bubbles and noises were generated near the graphite electrode , and the yellow green liquid was produced, which affected the further test.Through the study of graphite electrode, it was found that NaCl solution magnetic fluid produced hydrogen and chlorine gas after electrolysis. At the same time, chlorine gas dissolved in water to form yellow green liquid.The magnetic field of neodymium boron permanent magnet was equivalent to a mechanical stirring, which inhibited the production of chlorine gas.According to the difference of impressed current system, the abrasive magnetic fluid jet technology was divided into DC and AC(alternating current) .There was no electrode in AC abrasive magnetic fluid jet technology, so no gas or noise would be produced.The rotating magic ring permanent magnet produced alternating magnetic field, acting on the abrasive magnetic fluid to form an induced current.Under the action of the magnetic field, the electromagnetic force was applied to move along the circumferential direction to promote the motion of the abrasive magnetic fluid.

Abstract: The structure and magnetic properties of the Nd₃Fe_27.7-xNi_xTi_1.3 compounds prepared by arc-melting method have been investigated by means of X-ray diffraction and magnetization measurement. It was found that all the compounds crystallized in Nd₃(Fe, Ti)₂₉-type structure with monoclinic symmetry and A2/m space group in concentration range 0.2 ≤ x ≤ 1.2. The unit cell volume decreased slightly with increasing Ni content. The X-ray diffraction patterns of the magnetically aligned samples showed that all compounds investigated had planar anisotropy. The Spin reorientation phenomena occurred in all the compounds. As the increase of Ni content, the Curie temperature T_C monotonously increased, but the spin reorientation temperature T_sr did not obviously change. The saturation magnetization Ms of the compounds decreased monotonously with increasing Ni content at 5 K, 105 K, 205 K, and 305 K. The anisotropy fields B_a at 5 K, 305 K and anisotropy constant K₂ at 305K appeared as a minimum, but the anisotropy constant K₁ at 305 K appeared as a maximum on x = 0.6.

Abstract: Analytical models of vibration exciters and shakers are of great importance to their dynamic analysis and control. Furthermore, the modeling of the drive torque/force of the driving principle plays a key role in the modeling of an entire driving system. This paper aims to find a more detailed analytical model of the electromagnetic drive torque on the permanent magnet with a new shape in a novel driving mechanism. The proposed model contains all the related parameters instead of treating them as only one variable. Two methods of the permanent magnet installation are firstly introduced and compared. Based on the magnetic charge model, torque models of the bipolar cylindrical permanent magnet and partial bipolar cylindrical permanent magnet are then obtained. Thereupon then the final model with a composite shape is gained by combining the cylindrical and partial cylindrical ones. Moreover, all analytical models are verified by finite element method and it is found the final detailed model can characterize the electromagnetic drive torque in a high accuracy.

Abstract: The use of glass fibre reinforced polymer composite materials (GFRP) increases due to its superior properties that draw the attention of the other researches focusing on relevant aspects concerning the machining of such materials. In conventional machining for hole creation, drilling is the most frequently employed machining process for hole generation in fibre reinforced materials. Due to the laminated structure of the composite materials, several types of damages and other surface irregularities are introduced during drilling processes. These defects in the holes lead to about 60% of the rejections in assembly plant. Surface roughness has been identified to be the main contribution for defects in holes machined in composites. These defects would create reduction in structural stiffness, which may lead to variation of dynamic performance of the whole structure. Hence, achieving the desired hole quality is of great importance for the functional behaviour of the mechanical parts. In the present work, the effect of permanent magnet on the quality of drilled holes on GFRP composite is presented. Experiments are performed under different magnetic drilling conditions of spindle speed, feed rate and drill diameter on CNC drilling machine using three levels of factors. A procedure has been adopted to assess and optimize the chosen factors by the use of Box Behnken design to analyse the effects of different parameters. From the experimental results, it has been observed that the technique used is convenient to predict the main effects and their interaction effects of different influential combinations of machining parameters on surface roughness. It has been found that effect of permanent magnetic on the guiding mechanism of the drill bit which lead to get improved surface roughness with better circularity compared to normal drilling processes. A mathematical model has been developed for the prediction of surface roughness using permanent magnet and normal drilling processes.

Abstract: Response characteristics in the opening and closing operations of the micro magnetic fluid diaphragm mechanism by the alternating magnetic field are described. The micro magnetic fluid diaphragm mechanism was composed of a ring shaped permanent magnet and kerosene-based magnetic fluid. The driving principle of micro magnetic fluid device was based on the surface phenomena of magnetic fluid adsorbed on a permanent magnet. The opening and shutting time of diaphragm mechanism in the alternating magnetic field was measured by high-speed video camera system. The details of magnetic fluid surface response in the opening and closing operations of magnetic fluid hole were revealed experimentally.

Abstract: Responses of a magnetic fluid interface adsorbed on a small permanent magnet in water container subjected to an alternating magnetic field were studied with a high-speed video camera system. The directions of the external alternating magnetic field were parallel and anti-parallel to that of the permanent magnet. It was found that the interface of water-magnetic fluid responds to the external alternating magnetic field in elongation and contraction with Rosensweig instability at the interface. Frequency characteristics of the interface response of water-magnetic fluid system subjected to alternating magnetic field were revealed over a wide frequency band experimentally.

Abstract: This paper presents a review of the research activities carried out at the Laboratory for Electroheat of Padova University (LEP) in the field of high efficiency through heating of aluminum workpieces. Induction heating obtained by rotating a billet in a DC magnetic field produced by superconductive coils was the first attempt to reach high electrical efficiency in mass heating of high conductive metals, like aluminum, copper and brass. More recently, the same concept has been applied by rotating rare earth permanent magnets around a metal billet kept in a fixed position. This technology appears much more promising because of lower cost of installation and a more robust mechanical design.