Construction of magnetic nanochains to achieve magnetic energy coupling in scaffold

Cijun Shuai,Xuan Chen,Chongxian He,Guowen Qian,Yang Shuai,SHUPING PENG,Youwen Deng,Wenjing Yang 한국생체재료학회 2022 생체재료학회지 Vol.26 No.3

Background: Fe3O4 nanoparticles are highly desired for constructing endogenous magnetic microenvironment in scaffold to accelerate bone regeneration due to their superior magnetism. However, their random arrangement easily leads to mutual consumption of magnetic poles, thereby weakening the magnetic stimulation effect. Methods: In this study, magnetic nanochains are synthesized by magnetic-field-guided interface co-assembly of Fe3O4 nanoparticles. In detail, multiple Fe3O4 nanoparticles are aligned along the direction of magnetic force lines and are connected in series to form nanochain structures under an external magnetic field. Subsequently, the nanochain structures are covered and fixed by depositing a thin layer of silica (SiO2), and consequently forming linear magnetic nanochains (Fe3O4@SiO2). The Fe3O4@SiO2 nanochains are then incorporated into poly l-lactic acid (PLLA) scaffold prepared by selective laser sintering technology. Results: The results show that the Fe3O4@SiO2 nanochains with unique core–shell structure are successfully constructed. Meanwhile, the orderly assembly of nanoparticles in the Fe3O4@SiO2 nanochains enable to form magnetic energy coupling and obtain a highly magnetic micro-field. The in vitro tests indicate that the PLLA/Fe3O4@SiO2 scaffolds exhibit superior capacity in enhancing cell activity, improving osteogenesis-related gene expressions, and inducing cell mineralization compared with PLLA and PLLA/Fe3O4 scaffolds. Conclusion: In short, the Fe3O4@SiO2 nanochains endow scaffolds with good magnetism and cytocompatibility, which have great potential in accelerating bone repair

스퍼터링 중 외부자기장이 자성박막의 자기적 특성에 미치는 영향

안현태 ( Hyun Tae Ahn ),임상호 ( Sang Ho Lim ),지광구 ( Kwang Koo Jee ),한준현 ( Jun Hyun Han ) 대한금속재료학회(구 대한금속학회) 2011 대한금속·재료학회지 Vol.49 No.6

A magnetic device which enables the application of a strong and uniform magnetic field to thin film during sputtering was designed for controlling the magnetic anisotropy using a three dimensional finite element method, and the effects of the external magnetic field on the magnetic properties of sputtered thin films were investigated. Both the intensity and the uniformity of the magnetic flux density in the sputter zone (50 mm ×50 mm) was dependent on not only the shape and size of the magnet device but also the magnitude of stray fields from the magnet. For the magnet device in which the distance between two magnets or two pure iron bars was 80-90 mm, the magnetic flux density along the direction normal to the external magnetic field direction was minimum. The two row magnets increased the magnetic flux density and uniformity along the external magnetic field direction. An Fe thin film sputtered using the optimized magnet device showed a higher remanence ratio than that fabricated under no external magnetic field.

Analysis on Seal Capacity of Magnetic Fluid Seal Using Ring Magnet

Jiawei Liu,Decai Li 한국자기학회 2022 Journal of Magnetics Vol.27 No.1

Magnetic fluid seal is one of the most mature applications of magnetic fluid. When the shaft has a large radial runout, the classical pole piece is easily damaged. Due to its small size, the commonly used pole piece structure harbors problems like poor seal performance under a large gap and poor processability. By exploring the distribution law of the magnetic field on the magnet’s surface, we provided theoretical support for the magnetic fluid seal using axially-magnetized ring magnets. New structures for the magnetic fluid seal using axially-magnetized slotted ring magnets and the magnetic fluid seal using radially-magnetized ring magnets were proposed. Then, comparisons were made between the classical magnetic fluid seal and the magnetic fluid seal using ring magnets. The results revealed that the magnetic fluid seal using axially-magnetized slotted ring magnets and the magnetic fluid seal using radially-magnetized ring magnets exhibited a certain seal capacity, which could replace the classical magnetic fluid seal structure.

바륨 페라이트를 함유한 알지네이트 자성 복합 입자의 제조

이덕연,오영일,김동현,김광만,김경남,이용근 大韓齒科器材學會 2004 대한치과재료학회지 Vol.31 No.1

Magnetic polymer composite materials with high coercivity have potential applications in medical diagnostic technologies, magnetic drug delivery, and hyperthermic cancer treatment. The purpose of this study was to prepare the magnetic composite particles by encapsulating barium ferrite powders with alginate and to investigate their physical and biological properties. 0.4 g of sodium alginate was dissolved in 20 ml of distilled water and different amount (0.4~4 g) of barium ferrite powder was dispersed in alginate solution using an ultrasonication method. The resulting barium ferrite-alginate slurry was added dropwise to a CaCl2 solution to form magnetic Ca-alginate composite beads. They were separated by filtration and washed several times with water and ethanol. The final product was then completely dried at 40℃ under vacuum to obtain brownish black powders (0.1~1 mm in size) with a high magnetic response when submitted to a small magnet. Average size of magnetic composite particles was dependent on the amount of barium ferrite and the viscosity of slurry . The morphological and dimensional analyses of magnetic composite particles were performed by optical microscopy and scanning electron microscopy. Magnetic polymer composite particle was found to maintain the high coercivity. The saturation magnetization value for magnetic Ca-alginate composites increased with the increase of the barium ferrite/alginate ratio. The amount of self-heating induced by hysteresis under an alternating magnetic field was measured as a function of barium ferrite/alginate ratio in distilled water. According to the results, the encapsulated magnetic composite is expected to be useful for hyperthermia and chemotherapy remarkably.

Magnetic-field-dependent Shear Modulus of a Magnetorheological Elastomer Based on Natural Rubber

양인형,윤지현,정재은,정운창,김진수,정경호,오재응 한국물리학회 2013 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.62 No.2

A magnetorheological elastomer (MRE) is a smart material that has a reversible and variable modulus in a magnetic field. Natural rubber, which has better physical properties than silicone matrices, was used as a matrix in the fabrication of the MREs used in this study. Carbonyl iron powder (CIP), which has a rapid magnetic reaction, was selected as a magnetic material to generate the magnetic-field-dependent modulus in the MREs. The MRE specimens were cured in an anisotropic mold, which could be used to induce a uniaxial magnetic field via permanent magnets, to control the orientation of the CIP, and the shear modulus of the MREs was evaluated under a magnetic field induced by using a magnetic flux generator (MFG). Because the use of a conventional evaluation system to determine the magnetic-field-dependent shear modulus of the MREs was difficult, an evaluation system based on single degree-of-freedom vibration and electromagnetics that included an MFG, which is a device that generates a magnetic field via a variable induced current, was designed. An electromagnetic finite element method (FEM) analysis and design of experiments (DoE) techniques were employed to optimize the magnetic flux density generated by the MFG. The optimized system was verified over the range to determine the magnetic flux density generated by the MFG in order to use a magnetic circuit analysis to identify the existence of magnetic saturation. A variation in the shear modulus was observed with increasing CIP volume fraction and induced current. The experimental results revealed that the maximum variation in the shear modulus was 76.3% for 40 vol% CIP at an induced current of 4 A. With these results, the appropriate CIP volume fraction, induced current, and design procedure of the MFG can be proposed as guidelines for applications of MREs based on natural rubber.

여러가지 자기장 배치 기법에 따른 자성유체 속도 및 압력 분포에 관한 수치해석적 연구

송준호(Joon-Ho Song),이육형(Yuk-Hyung Lee),배형섭(Hyung-Sub Bae) 한국기계가공학회 2008 한국기계가공학회지 Vol.7 No.2

In this paper, we analyzed the dynamic behavior of magnetic fluid in a circular pipe with multiple permanent magnets. Magnetic fluid react on magnetic field against the normal fluid. In other words, magnetic fluid flow has the electromagnetism and fluid mechanics. So magnetic fluids has studied about the fluids properties and experiment. In this paper we studied the magnetic fluids velocity and pressure distribution for the novel type actuator. Because the velocity and pressure distribution is the important element of the magnetic fluids flow. First, we analyzed the Maxwell equation for the multiple permanent magnet and then concluded the governing equations for the magnetic fluid flow using the equation of Navier-Stokes. And, we simulated the dynamic behavior of magnetic fluid flow using the FEM(Finite Element Method). And we illustrated the relation between magnetic field and dynamic behavior of magnetic fluid flow.

Sr-Ferrite와 GC를 이용한 자기연마재 개발

윤여권 ( Yeo Kwon Yun ),김상백 ( Sang Baek Kim ),김희남 ( Hee Nam Kim ) 한국안전학회(구 한국산업안전학회) 2011 한국안전학회지 Vol.26 No.2

The magnetic polishing is the useful method to finish using magnetic power of magnet. That method is one of precision polishing techniques and has an aim of the clean technology using for the pure of gas and inside of the clean pipe. The magnetic abrasive polishing method is not so common for machine that it is not spreaded widely. There are rarely researcher in this field because of non-effectiveness of magnetic abrasive. Therefore, in this paper deals with development of the magnetic abrasive using Sr-Ferrite. In this development, abrasive grain GC used to resin bond fabricated low temperature. And Sr-Ferrite of magnetic abrasive powder fabricated that Sr-Ferrite was crused into 200 mesh. The XRD analysis result show that only GC abrasive and Sr-Ferrite crystal peaks detected which explains resin bond was not any more chemical reaction. From SEM analysis it is found that GC abrasive and Sr-Ferrite were strong bonding with each other by bond. The magnetic polishing is performed by polishing the surface of pipe by attracting magnetic abrasives with magnetic fields. This can be widely applied for finishing machinery fabrications such as various pipes and for other safety processes. In this paper, we could have investigated in to the changes of the movement of magnetic abrasive grain. In reference to this result, we could have made the experiment which is set under the condition of the magnetic flux density, polishing velocity according to the form of magnetic brush.

아몰퍼스 자성박대의 자기센서 응용에 관한 연구

金大柱,林在根,金玄郁,愼鏞鎭 明知大學校 産業技術硏究所 2002 産業技術硏究所論文集 Vol.21 No.-

In this thesis, we have described about application of amorphous magnetic ribbon of FeCoSiB compound to magnetic sensing device. As the samples of our experiment, we used a near zero-magnetostrictive amorphous magnetic ribbon of (Fe0.06Co0.94)79Si2.1B18.9 composition with its thickness of 26[㎛], its length of 5[㎝] and its width of 2[㎜], which was fabricated by rapidly quenching method. In order to improve the magnetic properties of the samples, we annealed them under magnetic field where the range of the crystallization temperature Tx and the Curie temperature Tc were 300~400[℃]. Then, by measuring them with X-ray diffraction(XRD) and vibrating sample megnetometer(VSM) analysis method. we found Tx≒451[℃] and Tc≒441[℃]. From the hysteresis curve of the finally annealed sample ribbon, we found the Large Bakhausen Jump(LBJ) effect at the reversal magnetization field Hw≒0.5[Oe]. This LBJ effect was also observed at the variation of the magnetic domain in the process of magnetization. Thus, it is proved that the amorphous magnetic ribbon of FeCoSiB compound can be use as a magnetic sensing device.

Effect of Nb/Zr co-addition on the Microstructure and Magnetic Properties of Fe<SUB>77.5</SUB>Si<SUB>11.5</SUB>B<SUB>7.5</SUB>Nb<SUB>x</SUB>Zr<SUB>3-x</SUB>Cu₁ nanocrystalline soft magnetic Alloys

Hyun Ah Im,Subong An,Yeong Gyun Nam,Sangsun Yang,Jung Woo Lee,Jae Won Jeong 한국자기학회 2021 한국자기학회 학술연구발표회 논문개요집 Vol.31 No.2

Soft magnetic materials require magnetic properties such as high permeability(μ), high saturation magnetic flux density(Bs), and low core loss. Silicon electronical is widely used due to high saturation flux density and low material cost, however it is difficult to satisfy low coercivity (Hc) and low core loss. Soft magnetic Fe-Si-B-Nb-Cu (Finemet) nanocrystalline alloys have been used as magnetic components in high frequency transformers, inductors due to their low coercivity, high permeability. Comparing to Silicon electronical Finemet has low saturation magnetic flux density(1.23T). Therefore, it is inevitable to develop Fe-based nanocrystalline soft magnetic materials with high saturation magnetic flux density and excellent soft magnetic properties. Nanocrystalline materials have the best soft magnetic properties when the crystal size is 10-15 nm. The purpose of this study is to minimize grain size and to enhance the soft magnetic properties. Zr distributed in amorphous residual matrix suppress grain growth, increasing the permeability and lowering the core loss and coercivity. Nb atoms also suppress grain growth and impending Fe₂B formations. However, Nb is problematic in terms of cost. To improve cost problem, we design our nanocrystlline alloys substitute Nb with Zr. Also according to previously studies W. Lu et al., it has been reported that simultaneous co-addition of transition elements resulted in a significant reduction in particle size to 10-20 nm. In this study, nanocrystalline ribbons with a composition of Fe77.5Si11.5B7.5NbxZr3-xCu₁(x=0-3) have been fabricated by rapid-quenching melt spinning and thermal annealing. The ratio of (Zr/Nb) effects on microstructure and magnetic properties. Among the alloys investigated in this work, Fe77.5Si11.5B7.5Nb₁Zr₂Cu₁ nanocrystalline ribbon annealed at 580 ℃ exhibits excellent soft-magnetic properties including low coercivity, low core loss, and high saturation magnetization. The uniform nanocrystallization in Fe77.5Si11.5B7.5Nb₁Zr₂Cu₁ alloy has been also confirmed through high-resolution TEM analysis.

Fabrication and magnetic properties of hexagonal BaFe12O19 ferrite obtained by magnetic-field-assisted hydrothermal process

Min Zhang,Jianming Dai,Qiangchun Liu,Qiang Li,Zhenfa Zi 한국물리학회 2018 Current Applied Physics Vol.18 No.11

High magnetic field effects on the microstructure and magnetic properties of BaFe12O19 hexaferrites synthesized hydrothermal method have been investigated. The obtained results indicate that the lattice constant decreases gradually as the magnetic field strength increases, which may be attributed to the lattice distortion resulted from the high magnetic field. Polycrystalline BaFe12O19 samples prepared under magnetic field strength at zero and 5 T are single phase. It is found that application of external magnetic field during synthesis can induce orientated growth of the hexaferrite crystals along the easy magnetic axis. The magnetic properties can be effectively regulated by an application of high magnetic fields. It is observed that the BaFe12O19 prepared under a 5 T magnetic field exhibits a higher room-temperature saturation magnetization (66.3 emu/g) than that of the sample (43.6 emu/g) obtained without magnetic field. The results can be explained as the enhanced crystalline, improvement of Fe3+ ions occupancy and the oriented growth induced by the external magnetic field. The growing orientation of particles gives rise to increased coercivity due to the enhancement in shape anisotropy. It is expected that an application of magnetic field during the formation of magnetic nanoparticles could be a promising technique to modify magnetic properties with excellent performance.