• 한국주조공학회지
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• 제7권2호
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• pp.108-113
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• 1987

Al-Cr alloy with composition in the range from 1.5 wt% to 10 wt% Cr were rapidly solidified from the melt by the single roller method. The supersaturated solid solution was obtained up to 6 wt% Cr in Al-Cr alloy for $20{\mu}m$ thickness. Lattice parameter decreased with increasing Cr content at the rate of 0.00456A per wt% Cr up to 6 wt% Cr. Microhardness increased with increasing Cr content at the rate of $10\;Kg/mm^2$ per wt% Cr up to 6 wt% Cr. Microhardness measurements on the Al-6 wt% Cr supersaturated solid solution annealed isothermally showed no sign of age hardening. Decomposition temperature, determined by lattice parameter changes and microhardness changes, was $470^{\circ}C$ for Al-6 wt% Cr supersaturated solid solution. Transmission electron microscopy showed that decomposition within one hour below $400^{\circ}C$ occurred at grain boundaries only, and also the additional decomposition within grains being evident at $450^{\circ}C$ The coarse precipitate structure showed at $500^{\circ}C$ and $550^{\circ}C$, respectively. The coarse precipitate structure is considered $Al_7Cr$.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 하계학술대회 논문집 C
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• pp.1399-1401
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• 2001

We studied on structure and resistivity, temperature coefficient of resistance (TCR) of NiCr and NiCr-N thin resistor films prepared by do reactive magnetron sputtering of NiCr target. It is found that while pure NiCr films are polycrystalline, an addition of nitrogen (N2/(Ar+N2) ratios are between 10% and 70%) into the film is changed into amorphous structure and sheet resistance of films is increased. Measurement temperatures of TCR are ratios of $5^{\circ}C$ per 15min from $25^{\circ}C$ to $130^{\circ}C$. TCR for an as-deposited NiCr-N thin film is varied from positive to negative.

• 한국재료학회지
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• 제20권4호
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• pp.187-193
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• 2010

Chromium nitride (CrN) samples with two different layer structures (multilayer and single layer) were coated on bipolar plates of polymer electrolyte membrane fuel cells (PEMFC) using the reactive sputtering method. The effects with respect to layer structure on corrosion resistance and overall cell performance were investigated. A continuous and thin chromium nitride layer ($Cr_{0.48}\;N_{0.52}$) was formed on the surface of the SUS 316L when the nitrogen flow rate was 10 sccm. The electrochemical stability of the coated layers was examined using the potentiodynamic and potentiostatic methods in the simulated corrosive circumstances of the PEMFC under $80^{\circ}C$. Interfacial contact resistance (ICR) between the CrN coated sample and the gas diffusion layer was measured by using Wang's method. A single cell performance test was also conducted. The test results showed that CrN coated SUS316L with multilayer structure had excellent corrosion resistance compared to single layer structures and single cell performance results with $25\;cm^2$ in effective area also showed the same tendency. The difference of the electrochemical properties between the single and multilayer samples was attributed to the Cr interlayer layer, which improved the corrosion resistance. Because the coating layer was damaged by pinholes, the Cr layer prevented the penetration of corrosive media into the substrate. Therefore, the CrN with a multilayer structure is an effective coating method to increase the corrosion resistance and to decrease the ICR for metallic bipolar plates in PEMFC.

• Journal of Magnetics
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• 제7권3호
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• pp.115-125
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• 2002

We proposed a novel method to evaluate the magnetic properties of the initial layer and the columnar structure separately for CoCr-based perpendicular recording media. We show that the thickness of the initial layer and the intrinsic magnetocrystalline anisotropy of columnar structure can be quantitatively evaluated using the plotted product of perpendicular anisotropy to magnetic film thickness versus magnetic film thickness ($K_{u{\bot}}^{ex{p.}}$ $\times$ d$_{mag.}$ vs. d$_{mag.}$ plot). Based on the analyses, it is found that: (1) compared with CoCrPtTa media, CoCrPtB media have relatively thin initial layer, and have fine grains with homogeneous columnar structure with c-plane crystallographic orientation; (2) CoCrPtB media can be grown epitaxially on Ru or CoCr/C intermediate layer, and as the result, the magnetic properties of the media within thin thickness region of d$_{mag.}$ $\leq$ 20 nm is significantly improved; (3) the key issue of material investigation for CoCr-based perpendicular recording media will be focused on how to fabricate c-plane-oriented columnar grains well isolated with nonmagnetic substance in epitaxial-growth media, while maintaining the thermal stability of the media.

• Bulletin of the Korean Chemical Society
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• 제25권7호
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• pp.977-982
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• 2004

The reaction of $cis-[Cr([14]-decane)(OH_2)_2]^+$ ([14]-decane = rac-5,5,7,12,12,14-hexamethyl-1,4,8,11-teraazacyclotetradecane) with auxiliary ligands {$L_a$ = benzoate(bz) or chlorobenzoate(cbz)} leads to a new compound $[Cr([14]-decane)(bz)_2]ClO_4$ or $[Cr([14]-decane)(cbz)_2]ClO_4$. These complexes have been characterized by a combination of elemental analysis, conductivity, IR and Vis spectroscopy, mass spectrometry, and X-ray crystallography. The crystal structure of $[Cr([14]-decane)(cbz)_2]^+$ was determined. The complex shows a distorted octahedral coordination environment with the macrocycle adopting a folded cis-V conformation. The angle $N_{axial}-Cr-N_{axial}$ deviates by $14.5^{\circ}$ from the ideal value of $180^{\circ}$for a perfect octahedron. The bond angle cis-O-Cr-O between the Cr(III) ion and the two carboxylate oxygen atoms of the monodentate p-chlorobenzoate ligands is close to 90$^{\circ}$. The FAB mass spectra of the $cis-[Cr([14]-decane)(La)_2]ClO_4$ display peaks due to the molecular ions $[Cr([14]-decane)(bz)_2-H]^\;,\;[Cr([14]-decane)(cbz)_2-2H]^$ at m/z 578, 646, respectively.

• 한국자기학회지
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• 제16권2호
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• pp.115-120
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• 2006

자기구조가 복잡한 것으로 알려져 있는 $Cr_2Te_3$의 전자구조와 자기구조를 이론적 방법으로 연구하였다. LDA+U 방법에 의해 Cr-d 전자의 상관효과를 고려해서 계산하면 전자의 상태밀도와 자기모멘트가 국소밀도근사(LDA)에 의한 것보다 실험과 더 잘 일치하는 것을 보였다. 이 과정에서 $Cr_2Te_3$에서 Cr-d 전자의 상관효과의 크기 U=1.7 eV를 구했다. $Cr_2Te_3$의 강자성 상태와 준강자성 상태의 에너지가 같아서 축퇴된다면 실험에서 알려진 Cr의 자기모멘트를 설명할 수 있음을 보였다.

• 한국재료학회:학술대회논문집
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• 한국재료학회 1996년도 재료학회 춘계학술발표회
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• pp.24-24
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• 1996

• 열처리공학회지
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• 제6권4호
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• pp.194-203
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• 1993

Rapid solidified splats Al-(1, 3, 5Cr) Alloys were produced by atomization-splat quenching method. Effects of mechanical alloying on the structure and mechanical properties of rapidly solidified Al-(1, 3, 5)Cr alloys were studied. Degree of mechanical alloying of Al-(1, 3, 5)Cr alloys can be determined by observing the microstructural refinement, microhardness and microstructure of Al-(l, 3, 5)Cr splats during processing. In the initial stage of mechanical alloying of the Al-(1, 3, 5)Cr splats fracturing of the grain boundaries occured first, followed after fracturing of zone A regions. Saturation hardness of Al-(1, 3, 5)Cr alloys increased proportionally with increasing concentration of the solute (Cr). Age hardening was not observed in these alloys. Decomposition temperature of Al-1Cr splats after mechanical alloying was higher than that of Al-5Cr splats. The density of $Al_7$ Cr precipitates increased proportionally with increasing chromium content, as a result, there was a transition to finely and spherically dispersed phase after mechanical alloying.

• 한국전기전자재료학회논문지
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• 제13권8호
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• pp.704-710
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• 2000

Metal electrode materials for plasma display panel should have low electrical resistivity in order to maintain stable gas discharge and have fast response time. They should also hae good film uniformity adhesion and thermal stability. In this study Cr/Cu/Cr metal electrode structure is formed by DC magnetron sputtering. Cr and Cu films were deposited on ITO coated glasses with various DC power density and main pressures as the major parameters. After metal electrodes were formed a heat treatment was followed at 55$0^{\circ}C$ for 20 min in a vacuum furnace. The intrinsic stress of the sputtered Cr film passed a tensile stress maximum decreased and then became compressive with further increasing DC power density. Also with increasing the main pressure stress turned from compression to tension. After heat the treatment the electrical resistivity of the sputtered Cu film of 2${\mu}{\textrm}{m}$ in thickness prepared at 1 motor with the applied power density of 3.70 W/cm$^2$was 2.68 $\mu$$\Omega$.cm With increasing the main pressure the DC magnetron sputtered Cu film became more open structure. The heat treatment decreased the surface roughness of the sputtered Cr/Cu/Cr metal electrodes.

• 한국자기학회지
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• 제5권5호
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• pp.442-446
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• 1995

Electronic structures of Fe overlayers on Cr(Fe/Cr) films, with an Fe coverage of $1-20{\AA}$, have been investigated by using photoemission spectroscopy. Experimental results are compared with supercell band structure calculations for a system with monolayer (ML) Fe on each side of five layer Cr, Fe(1ML)/Cr(5ML)/Fe(1ML). The extracted Fe 3d partial spectral weight in Fe/Cr exhibits very interesting features for very thin Fe overlayers. First, a sharp emissionnear the Fermi energy is observed, which is expected to originate primarily from hybridization between Fe and Cr 3d electrons at the Fe/Cr interface, and partially from the Fe 3d surface states in the Fe overlayer. Second, other structures are observed at higher binding energies which resemble the Cr 3d valence bands, also suggesting large hybridization between Fe and Cr 3d states at the Fe/Cr interface. These conjectures are confirmed by band structure calculations for Fe(1ML)/Cr(5ML)/Fe(1ML).