• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.28 no.12
• /
• pp.792-796
• /
• 2015

With high integration of electronic components, power inductors are also miniaturized. Recently, thick film processes for small size power inductors were developed and commercialized. However, the thick film process to prepare soft magnetic green sheets was not reported enough. In this study, we used Fe-Si magnetic and CIP (carbonyl iron powders) as starting materials to lead to a bimodal particle size distribution in the sheet. We proposed a newly developed 'Modified slurry preparation process' to get well dispersed condition even at high solid contents. Using the new process, it was possible to prepare a well dispersed slurry over 70 vol% of solid. BYK-103 was better than BYK-111 as dispersant in this slurry and the optimum amount was 0.6 wt%. The optimized slurry was formed into a sheet by tape casting process and then the sheet was laminated. We conformed that small size powder, large size powder, and epoxy resin were well dispersed in the green sheet.

• Korean Journal of Metals and Materials
• /
• v.49 no.6
• /
• pp.505-513
• /
• 2011

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 ${\times}$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.

• Journal of Magnetics
• /
• v.2 no.1
• /
• pp.16-21
• /
• 1997

Those were investigated, the crystallographic, morphological, and magnetic properties of barium ferrite film (SiO2/Si substrate) prepared by sol-gel dip coating. Appropriate sol was prepared by dissolvin barium and iron nitrate in ethylene glycol at 80$^{\circ}C$. To obtain the films, thermally oxidized p-type silicon substrate with (111) of crystallographic orientation were dipped into the sol, dried at 250$^{\circ}C$ to remove organic material, and heated at 800$^{\circ}C$ for 3 hours in air for the crystallization of barium ferrite. It was found that the particles of barium ferrite formed on the substrate exhibited needle-like shape placing parallel to the substrate and its c-axis is long axis direction. There was tendency that the coercive force in horizontal direction to the substrate was higher than that in vertical direction to it. This tendency was profound in large thickness.

• Corrosion Science and Technology
• /
• v.7 no.2
• /
• pp.112-118
• /
• 2008

We observed initial rusting process of steel containing Al under wet/dry cyclic condition with NaCl solution film using in situ X-ray diffraction spectroscopy at SPring-8 synchrotron radiation facility. It was found that mass fraction of iron oxides such as ${\alpha}-FeOOH$, ${\beta}-FeOOH$ and ${\gamma}-FeOOH$ varied with Al content. Some kinds of Al oxides were also found at the initial stage of corrosion. Those corrosion products might affect the corrosion process and corrosion rate of the steel.

• Tribology and Lubricants
• /
• v.25 no.5
• /
• pp.348-358
• /
• 2009

To satisfy the more severe emission regulation and the demand of higher fuel economy in near future, the combustion pressure and power output of engines is going to be higher. In order to get the reduction of engine emission and the higher power, it is needed the reduction of the tension and width of ring pack. The lower tension ring and the manufacturing technology of cast iron thinner width ring can bring the friction reduction between the ring and liner during engine running. Therfore, the fuel economy can be achieved. Thereafter the engine emission can be reduced. In this study, by using a developed basic computer program that predicts the inter-ring pressure, the motion of ring and the inter-ring pressure through a crevice volume model between adjacent rings, and the oil film thickness and the friction computed by lubrication theories, it is to be examined the effect of friction reduction from piston ring pack equipped with thinner width ring and lower tension ring.

• Journal of the Korean Magnetics Society
• /
• v.1 no.2
• /
• pp.22-30
• /
• 1991

고주파 마그네트론 스퍼터링법으로 제조된 순철박막에 대해 증착속도, 미세구조 및 자기특성에 미치는 스퍼터링조건의 영향을 조사하였다. 증착속도는 기판에 자장을 가할 경우 현저히 증가햐였으며, 이는 자장에 의한 Ar 이온의 증가효과로 고찰되었다. 투입전력이 커질수록 결정립 크기와 격자상수가 증 가하였으며 (110)면이 강하게 발달하였다. Ar 압력의 증가에 따라 격자상수는 작아졌으나 결정립 크기는 거의 변화하지 않았다. 기판자장을 가하면서 60W에서 제조한 순철박막의 자화곤란방향이 가장 낮은 약 30e의 보자력을 나타내었다. 보자력은 5mTorr 이상의 Ar 압력에서 급증하는 경향을 보였으며, 이는 표면 이 거칠어진 효과 및 제2상의 효과로 고찰되었다. 두께에 따른 보자력의 변화는 50-200nm 두께의 범위에 서 Neel의 관계를 잘 만족하였다.

• Journal of Welding and Joining
• /
• v.32 no.5
• /
• pp.13-20
• /
• 2014

A brief overview is given of the corrosion and hydrogen diffusion behaviors of high strength pipe steel in sour environment. Firstly, hydrogen adsorption and diffusion mechanism of the pipe steel is introduced. Secondly, the effect of iron sulfide film precipitated as a result of the corrosion reaction on the steel surface on hydrogen reduction reaction and subsequent hydrogen permeation through the steel is discussed. Moreover, the hydrogen diffusion behavior of the pipe steel under tensile stress in both elastic and plastic ranges is reviewed based on a number of experimental permeation data and theoretical models describing the hydrogen diffusion and trapping phenomena in the steel. It is hoped that this paper will result in significant academic contributions in the field of corrosion and hydrogen related problems of the pipe steel used in sour environment.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.14 no.3
• /
• pp.257-262
• /
• 2001

Single crystalline films of La doped YIG(yttrium iron garnet) were grown by the liquid phase epitaxy. The lattice constants of films obtained by DCD(double crystalline diffractometer) measurement increased with increasing La contents in films. In particular, lattice constants of films grown wiht Y/La=20 solution were nearly same as those of GGG (gadolinium gallium garnet) substrate. The saturation magnetization measured with VSM (vibrating sample magnetometer) was about 1750Gauss which is the same as that of pure YIG irrespective of La contents in films. FMR(ferromagnetic resonance) linewidth of La doped YIG was smaller than that of pure YIG. Since appropriate La doping decreases the lattice mismatch between film and substrate, the FMR linewidth was Y/La=20 in this experiment.

• 한국초전도학회:학술대회논문집
• /
• 2009.07a
• /
• pp.16-16
• /
• 2009

• Journal of Magnetics
• /
• v.11 no.3
• /
• pp.147-150
• /
• 2006

We have fabricated three-dimensional magnetophotonic crystals based on $\alpha$-$SiO_2$ opal films. Opal thin films grown on glass substrates were filled with bismuth substituted iron garnet (Bi:YIG). Scanning electron microscopy data, optical and magnetic properties of the synthesized samples confirm the presence of the Bi:YIG contentin the opal lattice. It is shown that the samples exhibit the (111) stop band, and transmissivity of the threedimensional magnetophotonic crystals is defined by both the film lattice and the Bi:YIG content.