• Title, Summary, Keyword: CR-structure

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Composition and Microstructure of Electroplated Zinc-Chromium Alloy according to Electrolysis Conditions (전해조건에 따른 아연-크롬합금 도금층의 조성 및 조직특성)

  • 안덕수;김대영;예길촌
    • Journal of the Korean institute of surface engineering
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    • v.35 no.4
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    • pp.232-240
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    • 2002
  • The composition and the microstructure of the Zn-Cr alloys electroplated in chloride bath with EDTA were studied according to electrolysis conditions. The cathode current efficiency decreased with increasing both Cr/(Cr+Zn) ratio and current density. The Cr content of the alloy deposits increased with Cr/(Cr+Zn) ratio and current density The phase structure of Zn-Cr alloy deposits changed from η-Zn through η-Zn+${\gamma}$'-ZnCr to ${\gamma}$'-ZnCr with increasing Cr content of alloys. The surface morphology of Zn-Cr alloy deposits changed from fine needle shaped crystallites through the mixed structure of needle-shaped and granular one to the colony structure with fine granular crystallites according to the change of phase structure

Solid Solution and Defect Structure of LiCrO2 in the Pseudo-binary Systems : Li2Cr2O4-MgAl2O4 (의사이성분계, Li2Cr2O4-MgCr2O4와 Li2Cr2O4-MgAl2O4에서의 LiCrO2 고용체 형성과 결합구조)

  • 정영서;오근호;김호기
    • Journal of the Korean Ceramic Society
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    • v.25 no.1
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    • pp.35-41
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    • 1988
  • In the system of Li2O-MgO-Al2O3-Cr2O3, the crystalline solid solution of LiCrO2 along the pseudo-binary join between rocksalt structure(LiCrO2) and spinel structure(MgCr2O4 or MgAl2O4) have been investigated by x-ray diffraction techniques. In this study, order-disorder phase transition of LiCrO2 was observed and the unit cell of the disordered LiCrO2 structure has been established. It has been found that LiCrO2 makes a solid solution over a wide range with MgAl2O4, while not with MgCr2O4. This difference was explained as being due to the ability of oxygen lattice distortion which depended on the relative sizes and chemical bonding characteristics of the substituted ions.

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Self-Organized Nano Structure in Co-22% Cr Alloy Thin Films with Substrate Temperatures (기판온도에 따른 Co-22%Cr 합금박막의자가정렬형 나노구조)

  • 송오성;이영민
    • Journal of the Korean institute of surface engineering
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    • v.34 no.6
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    • pp.531-536
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    • 2001
  • Co-22 %Cr alloy films are promising for high-density perpendicular magnetic recording media with their perpendicular anisotropy and large coercivity of 3000 Oe. We observed that a self organized nano structure (SONS) of fine ferromagnetic Co-enriched phase and paramagnetic Cr-enriched phase appears inside the grain of Co-Cr magnetic alloy thin films at the elevated substrate temperature after do-sputtering. The periodic fine Co-enriched phase and Cr-enriched phase is the plate shape of 80 (equation omitted)-wide and 1000 (equation omitted)-long. Cr-enriched phases are located at the center of grains. We prepared 5000 (equation omitted) -thick Co-22 %Cr films on polyimide substrate with varying substrate temperature of $ 30^{\circ}C$, $ 150^{\circ}C$ ,200 $^{\circ}C$, $300^{\circ}C$, and $400^{\circ}C$, respectively. A transmission electron microscope equipped with energy dispersive X-ray analyzer is employed to observe the microstructure of each samples after Co-enri-ched phase are etched selectively. The self organized nano structure of Co-enriched and Cr-enriched lamellar is observed above the substrate temperture of $150^{\circ}C$. No compositional change is observed with substrate temperature. The compositional phase separation in self organized structure becomes clear as the substrate temperature increases. Our results implies that the self organized nano structure in Co-22 %Cr film is ideal for ultra high density recording media by recording selectively on Co-enri-ohed phase.

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Surface morphology, Glossiness and Hardness of Zn-Cr and Zn-Cr-X ternary alloy Electrodeposits (고속도금된 Zn-Cr 및 Zn-Cr-X 3원합금 도금층의 표면조직, 광택도 및 경도)

  • 예길촌;김대영;서경훈
    • Journal of the Korean institute of surface engineering
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    • v.36 no.5
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    • pp.379-385
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    • 2003
  • The surface morphology, the glossiness and the hardness of Zn-Cr and Zn-Cr-X(X:Co, Mn) alloy electrodeposits were investigated by using chloride bath with EDTA additive and flow cell system. The surface morphology of Zn-Cr alloy and Zn-Cr-Mn alloy changed from fine needle shape crystalline structure to colony structure of fine granular crystallites with increasing current density in the range of 20-100 $A/dm^2$. The surface morphology of Zn-Cr-Co alloy deposited from low Co concentration bath(2.5-10 g/$\ell$) was similar to that of Zn-Cr alloy, while that of Zn-Cr-Co alloy deposited from high cobalt concentration bath was fine granular crystalline structure in the same range of current density. The glossiness of Zn-Cr and Zn-Cr-Mn alloy increased noticeably with increasing current density, while that of Zn-Cr-Mn alloy decreased with increasing Mn concentration of bath in high current density region. The glossiness of Zn-Cr-Co alloy deposited from low Co concentration bath increased with current density while that of the alloy from high Co concentration bath decreased with increasing current density. The hardness of Zn-Cr and Zn-Cr-X alloy increased noticeably with current density.

Microstructural Features of Multicomponent FeCoCrNiSix Alloys

  • Kong, Kyeong Ho;Kim, Kang Cheol;Kim, Won Tae;Kim, Do Hyang
    • Applied Microscopy
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    • v.45 no.1
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    • pp.32-36
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    • 2015
  • The microstructural features of FeCoCrNi, FeCoCrNiAl and FeCoCrNiSix (x=0, 5, 10, 15, 20) alloys have been investigated in the present study. The microstructure of FeCoCrNi alloy changes dramatically with equiatomic addition of Al. The fcc irregular shaped grain structure in the as-cast FeCoCrNi alloy changes into the bcc interconnected structure with phase separation of Al-Ni rich and Cr-Fe rich phases in the as-cast FeCoCrNiAl alloy. The microstructure of FeCoCrNi alloy changes with the addition of Si. With increasing the amount of Si, the fcc structure of the grains is maintained, but new phase containing higher amount of Si forms at the grain boundary. As the amount of Si increases, the fraction the Si-rich grain boundary phase increases.

Amorphization Process of Cr-N Alloy System by Mechanical Alloying (기계적 합금화에 의한 Cr-N계 합금의 비정질화 과정)

  • 이충효;이성희;이상진;권영순
    • Journal of Korean Powder Metallurgy Institute
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    • v.10 no.4
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    • pp.288-293
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    • 2003
  • Mechanical alloying (MA) by high energy ball mill of Pure chromium Powders was carried out under the nitrogen gas atmosphere. Cr-N amorphous alloy powders have been produced through the solid-gas reaction subjected to MA. The atomic structure during amorphization process was observed by X-ray and neutron diffractions. An advantage of the neutron diffraction technique allows us to observe the local atomic structure surrounding a nitrogen atom. The coordination number of metal atoms around a N atom turns out to be 5.5 atoms. This implies that a nitrogen atom is located at both of centers of the tetrahedron and octahedron formed by metal atoms to stabilize an amorphous Cr-N structure. Also, we have revealed that a Cr-N amorphous alloy may produced from a mixture of pure Cr and Cr nitrides powders by solid-solid reaction during mechanical alloying.

The Population Genetic Structure of the Oyster Crassostera gigas (Bivalvia:Ostreidae) from Gamak Bay in Korea (가막산 참굴의 집단 구조 분석)

  • Cho, Eun-Seob;Jeong, Hee-Dong
    • Journal of Life Science
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    • v.18 no.7
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    • pp.1015-1018
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    • 2008
  • To analyze the population genetic structure of the oyster Crassostrea gigas Thunberg, 34 specimens werecollected from Gamak bay in March, 2007. Total genomic DNA was extracted from each sample and PCR was performed to identify haplotypes of oyster by using HCO2918 and LCO1491 primers. Four kinds of haplotypes (CR1, CR2, CR3, and CR4) were identified. Among these group, CR3 showed the highest relative frequency at 73% than any other of haplotypes. On the basis of hierarchical genetic structure, the population of Gamak showed a higher genetic relationship with Namhae, but the genetic distance between southern and western coasts was negative and no statistical significance was found (p>0.05). Consequently, the oyster from Korea coast is determined to be both homogenous and large.

Properties of Cr-N Films Prepared by the Arc-induced Ion Plating (아아크방전 유도형 이온플레이팅에 의한 Cr-N 피막의 특성)

  • 정재인;문종호;홍재화;강정수;이영백
    • Journal of the Korean institute of surface engineering
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    • v.25 no.1
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    • pp.24-33
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    • 1992
  • Cr-N films were deposited on low-carbon steel sheets by the reactive arc-induced ion plating (AIIP). The influence of the deposition conditions (nitrogen pressure and substrate bias voltage) on the crystal orientation, morphology and microhardness of the Cr-N films has been investigated using x-ray diffractometer and scanning electron microscope. The impurities and contaminations on the surface and at the interface, and the layer-by-layer compositions of the film have been analyzed using scanning Auger multiprobe (SAM) and glow discharge spectroscope (GDS). The mixed state of Cr and Cr₂N turned out to have a fine fibrous structure. The Cr₂N films were deposited at a wide range of nitrogen flow rates. The orientations of Cr₂N films were mainly (110) and (111), and the intensity of the (111) peak increased as the substrate bias voltage increased. The microstructure of the Cr₂N film was dense and no columnar structure was observed. The films in the mixed state of Cr₂N and CrN were also dense without columnar structure. The maximum microhardness of the Cr-N films was 2400 kg/㎟ at 10 gf load.

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A study on the structure and properties of Cr and Cr$_2$O$_3$ films deposited by the vacuum evaporation method (진공 증발법으로 증착한 Cr, Cr$_2$O$_3$ 박막의 조직 및 특성에 관한 연구)

  • 이종민;이정중
    • Journal of the Korean institute of surface engineering
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    • v.27 no.2
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    • pp.74-82
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    • 1994
  • The structure and properties such as adhesion and corrosion resistance of Cr and $Cr_2O_3$ films, deposited on steel plates by the vacuum evaporation method, were investigated. According to the ESCA and AES analy-sis, it could be concluded that chromium oxide with uniform composition could be formed on the steel sub-strate. The deposited Cr and $Cr_2O_3$ films had high adhesion strength, and they did not peeled off by the tape test. The adhesion property, however, was deteriorated as the film thciknes increased. After bending of the deposited specimen many cracks were observed by SEM, and they were assumed to have propagated along co-lumnar boundaries by the bending test. The corrosion resistance of the films was not generally good, which in-dicates that the films had a porous structure with a large number of defects such as pin holes and voids.

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E-Beam Evaporated Co/Cr and Co/Mo Multilayer Thin Films

  • Lee, S.K;Nam, I.T;Hong, Y.K
    • Journal of Magnetics
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    • v.4 no.2
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    • pp.69-72
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    • 1999
  • Magnetic properties and crystallographic structure of e-beam evaporated Co/Cr and Co/Mo multilayer thin films were investigated using VSM and XRD. Co/Cr and Co/Mo multilayer thin films are confirmed as an alternating layered structure. The structure of films with thicker Co layers than Cr and Mo layers are found to be a hcp structure with the c-axis perpendicular to the film plane. The direction of the film plane is the easy magnetization one. There is a no significant difference in shape of hysteresis loops between Co/Cr and Co/Mo multilayer films. It is found that Mo layer is more effective than Cr for preparing Co layer with c-axis normal to the film plane.

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