• Title/Summary/Keyword: Ni-Cr-Fe

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A study on the Fabrication of Graded-Boundary Ni-Cr/Steel Material by Laser Beam (레이저빔에 의한 계면경사 Ni-Cr/steel 재료 제조에 관한 연구)

  • 김재현;김도훈
    • Laser Solutions
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    • v.3 no.1
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    • pp.29-37
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    • 2000

  • For a development purpose of thick metal / metal Graded-Boundary Materials(GBM), a basic research on the fabrication of Ni-Cr/steel GBM was carried out by a laser beam and its mechanical properties and thermal characteristics were investigated. In order to produce a compositionally graded boundary region between substrate steel and added Ni-Cr alloy, a series of surface alloying treatments was performed with a high power CO$_2$ laser beam. Ni-Cr sheet was placed on a low carbon steel plate(0.18%C), and then a CO$_2$ laser beam was irradiated on the surface to produce a homogeneous alloyed layer. On this first surface-alloyed layer, another Ni-Cr sheet was placed and then the CO$_2$ laser beam was irradiated again to produce second surface-alloyed layer. Sequential repetitions of laser surface alloying treatment 4 times resulted in a graded-boundary region with the thickness of about 1.4mm. Simultaneous concentration profiles of different kinds of alloying elements(Ni and Cr) showed from 42%Ni, 45%Cr and 13%Fe on surface region to 0%Ni, 0%Cr and 99%Fe in substrate region. Also a thermal conductivity gradient resulted in graded-region and its value changed from 0.03㎈/cm s$\^{C}$ in surface region to 0.1㎈/cm s$\^{C}$ in substrate region. Microstructural observation showed that any visible root porosities and solidification shrinkage cracks were not formed in graded region between alloyed layer and substrate region during rapid cooling.

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Colossal Magnetoresistance in Chalcogenide Spinels $Ni_xFe_{1-x}Cr_2S_4(X = 0.05, 0.1, 0.2)$ (Spinel 유화물 $Ni_xFe_{1-x}Cr_2S_4(X = 0.05, 0.1, 0.2)$의 초거대자기저항(CMR)현상에 관한 연구)

  • 박재윤
    • Journal of the Korean Magnetics Society
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    • v.11 no.4
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    • pp.151-156
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    • 2001

  • Recently many studies on manganese oxides Ln$_{1-x}$A$_{x}$MnO$_3$(Ln=La, Pr, Nd lanthannide; A=Ca, Sr, Ba, Pb +2 ions) reported CMR properties. CMR have been also found in chalcogenide spinels. We have investigated that Ni ion substitutions for Fe ion have effects on CMR properties in chacogenide spinels Ni$_{x}$Fe$_{1-x}$Cr$_2$S$_4$. It was found that with increasing Ni concentration Jahn-Teller distortion was strengthened and Curie temperature T$_{c}$ was increased. CMR properties could be explained with Jahnl-Teller effect, half-metallic electronic structure, and the alignment of magnetic domain due to the strong magnetic field, which is different in that double exchange interactions dominate CMR properties in manganese oxides.

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Evaluations of corrosion resistance of Ni-Cr plated and Zn-plated Fe Substrates Using an Electrolytic Corrosion Test (전해부식시험을 이용한 니켈-크롬도금강판 및 아연도금강판의 내식성 비교평가시험)

  • Lee, Jae-Bong;Kim, Kyung-Wook;Park, Min-Woo;Song, Tae-Jun;Lee, Chae-Seung;Lee, Eui-Jong;Kim, Sang-Yeol
    • Corrosion Science and Technology
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    • v.12 no.1
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    • pp.56-64
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    • 2013

  • An Eectrolytic Corrosion(EC) test method was evaluated by the comparison with Copper Accelerated Acetic Salt Spray(CASS) and Neutral Salt Spray(SS) tests. Those methods were applied in order to evaluate corrosion resistance of Ni-Cr plated and Zn-plated Fe substrates. The correlations between results obtained by different test methods were investigated. Results showed that the electrochemical method such as the EC test method was superior to the conventional methods such as CASS and SS, in terms of the quantitative accuracy and the test-time span. Furthermore, the EC test method provided the useful means to estimate the initiation of corrosion of each layer by monitoring the rest potentials of the coated layers such as Ni, Cr, and Zn on Fe substrate. With regard to test time spans, the EC test provided the 78 times and 182 times faster results than the CASS test in cases of $Fe+5{\mu}m$ $Ni+0.5{\mu}m$ Cr and $Fe+20{\mu}m$ $Ni+0.5{\mu}m$ Cr respectively, while the EC test was 85 times faster results than the Salt Spray test in the case of $Fe+20g/m^2$ Zn. Therefore, the EC test can be the better method to evaluate the resistance to corrosion of coated layers than the conventional methods such as the SS test and the CASS.

  • https://doi.org/10.14773/cst.2013.12.1.056 인용 PDF KSCI