• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.16 no.12S
• /
• pp.1305-1309
• /
• 2003

To utilize FeCoSiB amorphous films for magnetoelastic sensors, the temperature dependency of magnetization (M-T curve) and the magnetization properties of the amorphous films were investigated in this study. As the amount of cobalt In the films increased, the Curie temperature decreased but the crystallization temperature increased. In addition to this, the crystallization temperature was lower than the Curie temperature in the film containing 20 at% cobalt. The optimized annealing condition was set up by analyzing the H-T curve. And then, the amorphous film that has excellent magnetic properties and uni-axal anisotropy could be prepared for construction of the magnetoelastic sensor devices. The coercive force of the film was below 0.5 Oe and the anisotripic field was about 5 Oe.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 1997.11a
• /
• pp.124-127
• /
• 1997

The magnetic properties of calcined Sr-ferrites, related to the iron oxides, produced from three different process in steel plants, have been investigated. The powder f.characteristics of iron oxides are much affected on the magnetic properties of calcined Sr-ferrite Powders. It was possible to improve the magnetic property of calcined Sr-ferrites with the iron oxide powders of small size and narrow size distribution. The maximum magnetic properties of calcined Sr-ferrites, showing 69 emu/g of saturation magnetization and 4020 Oe of intrinsic coercivity, are achieved at the following conditions; the iron oxides from the chemirite process(EP), mole ratio of 5.8, and calcination condition of 120$0^{\circ}C$/1hr.

• Proceedings of the Korean Powder Metallurgy Institute Conference
• /
• 2006.09a
• /
• pp.120-121
• /
• 2006

Magnetic properties of nanostructured materials are affected by the microstructures such as grain size (or particle size), internal strain and crystal structure. Thus, it is necessary to study the synthesis of nanostructured materials to make significant improvements in their magnetic properties. In this study, nanostructured Fe-20at.%Co and Fe-50at.%Co alloy powders were prepared by hydrogen reduction from the two oxide powder mixtures, $Fe_2O_3$ and $Co_3O_4$. Furthermore, the effect of microstructure on the magnetic properties of hydrogen reduced Fe-Co alloy powders was examined using XRD, SEM, TEM, and VSM.

• Korean Journal of Metals and Materials
• /
• v.50 no.3
• /
• pp.248-255
• /
• 2012

AlN thin films containing various amounts of Co, AlN-Co, and Al-Co alloy particles were prepared using a two-facing-target type dc reactive sputtering (TFTS) system. The as-deposited films exhibited the variable nature expected from an AlN-rich phase, and an amorphous-like phase, depending on the Co content in the films. Specific favorable microstructures were prepared by optimizing annealing conditions. Those microstructures and their magnetic properties and resistivity were investigated. As-deposited films showed very small saturation magnetization and an amorphous-like structure. However, when annealed, the as-deposited amorphous-like phase decomposes into phases of AlN, Co and Al-Co. These annealing induced changes in the microstructure improve the magnetization and resistivity of the films. Further improvement of soft magnetic properties could lead to the material being used for high density magnetic recording head material.

• Journal of Powder Materials
• /
• v.16 no.4
• /
• pp.285-290
• /
• 2009

HDDR treated anisotropic Nd-Fe-B powders have been widely used, due to their excellent magnetic properties, especially for sheet motors and sunroof motors of hybrid and electric vehicles. Final microstructure and coercivity of such Nd-Fe-B powders depend on the state of starting mother alloys, so additional homogenization treatment is required for improving magnetic properties of them. In this study, a homogenization treatment was performed at $900\sim1140^{\circ}C$ in order to control the grain size and Nd-rich phase distribution, and at the same time to improve coercivity of the HDDR treated magnetic powders. FE-SEM was used for observing grain size of the HDDR treated powder and EPMA was employed to observe distribution of Nd-rich phase. Magnetic properties were analyzed with a vibrating sample magnetometer.

• Korean Journal of Materials Research
• /
• v.14 no.11
• /
• pp.780-785
• /
• 2004

The degradation mechanism of soft magnetic properties of $Fe-Hf-N/Cr/SiO_2$ thin films reacted with a bonding glass was investigated. When $Fe-Hf-N/Cr/SiO_2$ films were annealed under $600^{\circ}C$ without the bonding glass, the compositions and the soft magnetic properties of Fe-Hf-N layers were not changed. However, after reaction with the bonding glass at $550^{\circ}C$, the soft magnetic properties of the film were degraded. At $600^{\circ}C$, the saturation magnetization of the reacted film decreased to 13.5 kG, and its coercivity increased to 4 Oe, and its effective permeability decreased to 700. It was founded that O diffused from the glass into the Fe-Hf-N layers during the reaction and generated $HfO_2$ phases. It was considered that the soft magnetic properties of the $Fe-Hf-N/Cr/SiO_2$ films reacted with the bonding glass were primarily degraded by the formation of the Fe-Hf-O-N layer of which the Fe content was below 60 $at\%$, and secondarily degraded by the Fe-Hf-O-N layer above 70 $at\%$.

• Journal of Powder Materials
• /
• v.14 no.5
• /
• pp.298-302
• /
• 2007

In recent years, a rapid increase in demands for the soft magnetic composite parts has been created and it has been tried to improve their properties by various processing methods, alloying elements and compaction parameters. Warm compaction method has been used for the reduction of residual stress, the improvement of magnetic properties and the higher densities. In this work, the effects of warm compaction and polymer binder on magnetic properties of Fe powder core were investigated. The sintering powder, Fe oxide, was ball-milled for 30n hours. And then ball-milled Fe oxide powder was reduced through hydrogen reduction process. The hydrogen reduced Fe powder and polymer binder were mixed by 3-D turbular mixer. And then the mixed powder was warm-compacted. The magnetic properties such as core loss and permeability were measured by B-H curve analyzer.

• Journal of Powder Materials
• /
• v.24 no.2
• /
• pp.122-127
• /
• 2017

Fe-6.5 wt.% Si alloys are widely known to have excellent soft magnetic properties such as high magnetic flux density, low coercivity, and low core loss at high frequency. In this work, disc-shaped preforms are prepared by spark plasma sintering at 1223 K after inert gas atomization of Fe-6.5 wt.% Si powders. Fe-6.5 wt.% Si sheets are rolled by a powder hot-rolling process without cracking, and their microstructure and soft magnetic properties are investigated. The microstructure and magnetic properties (saturation magnetization and core loss) of the hot-rolled Fe-6.5 wt.% Si sheets are examined by scanning electron microscopy, electron backscatter diffraction, vibration sample magnetometry, and AC B-H analysis. The Fe-6.5 wt.% Si sheet rolled at a total reduction ratio of 80% exhibits good soft magnetic properties such as a saturation magnetization of 1.74 T and core loss ($W_{5/1000}$) of 30.7 W/kg. This result is caused by an increase in the electrical resistivity resulting from an increased particle boundary density and the oxide layers between the primary particle boundaries.

• Journal of the Korean Magnetics Society
• /
• v.11 no.3
• /
• pp.114-121
• /
• 2001

Effect of sintering temperature and dusts content on sintered density ($\rho$) and magnetic properties were evaluated. Cores sintered at 1350 $^{\circ}C$ for 1 hour with the Fe powders containing up to 10 wt.% dusts showed a good AC/DC properties. For example, the DC magnetic properties of magnetic induction (B$_{15}$), coercive force (H$_{c}$) and permeability ($\mu$$_{max}$) of cores containing 10 wt.% dusts were ranging over 9.8~ 10.9 kG, 2.2-2.3 Oe and 1950~2050, respectively. These magnetic properties are equivalent to those of competitor's (i.e, Ancorsteel produced by Hoganas). The cores obtained from the present work are expected to apply for high-performance soft magnetic components such as automotive and DC motor.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.13 no.11
• /
• pp.963-968
• /
• 2000

Magnetic properties and microstructures of Fe$\_$93-x/Zr$_3$B$_4$Ag$\_$x/ thin films were investigated as a function of addition of element Ag, (X$\_$Ag/=0 to 6 at.%) and annealing temperature, T$\_$a/=300$\^{C}$ to 600$\^{C}$. In the case of adding Ag, magnetic properties of Fe$\_$93-x/Zr$_3$B$_4$Ag$\_$x/ thin films were improved than those of Ag-free Fe$\_$93/Zr$_3$B$_4$thin films. The prominent soft magnetic properties with coercivity of 1.1 Oe, saturation magnetization of 2.2 T and permeability of 5400 at 50㎒ were obtained from Fe$\_$88/Zr$_3$B$_4$Ag$\_$5/ thin film annealed was lower than that of Fe-base or Co-base thin films reported previously. Such enhanced magnetic properties are presumably attributed to the format in ultra fine grains. Also, the reduced eddy current loss in the annealed sample is due to refined micro magnetic domains with increasing the amount of Ag in Fe$\_$93-x/Zr$_3$B$_4$Ag$\_$x/ thin films.