• Journal of Hydrogen and New Energy
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• v.29 no.6
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• pp.549-558
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• 2018

The overall efficiency depend on the overpotential of the oxygen evolution reaction in alkaline water electrolysis. Therefore, it is necessary to research to reduce the oxygen evolution overpotential of electrodes. In this study, Ni-Zn-Fe electrodes were prepared by electroplating and the surface area was increased by Zn leaching process. Electroplating variables were studied to optimize the plating parameters(electroplating current density, pH value of electroplating solution, Ni/Fe content ratio). Ni-Zn-Fe electrode, which is electroplated in a modified Watts bath, showed 0.294 V of overpotential at $0.1A/cm^2$. That result is better than that of Ni and Ni-Zn plated electrodes. As the electroplating current density of the Ni-Zn-Fe electrode increased, the particle size tended to increase and the overpotential of oxygen evolution reaction decreased. As reducing pH of electroplating solution from 4 to 2, Fe content in electrode and activity of oxygen evolution reaction decreased.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.11a
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• pp.260-263
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• 2002

There is great interest in developing magnetoresistance(MR) sensor, using ferromagnetic, electrically non-magnetic conducting and antiferromagnetic films, especially for the use in weak magnetic fields. Here, we report single and Wheatstone-bridge type of MR sensors made in Si(001)/NiO($300{\AA}$)/NiFe bilayers. Angular dependence of MR profiles was measured in Si(001)/NiO($300{\AA}$)/NiFe($450{\AA})$ films as a function of an angle between current and applied field direction, also, linearity was determined. AMR characteristics of single MR sensors was well explained with single domain model. Good linearity in $45^{\circ}$ Wheatstone-bridge type of MR sensors consisting of 4 single MR sensors made in Si(001)/NiO($300{\AA}$)/NiFe($450{\AA})$ was shown in the range of about ${\leq}{\pm}5$ Oe.

• Resources Recycling
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• v.17 no.1
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• pp.80-87
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• 2008

Cementation and solvent extraction processes were studied to separate nickel and iron ions from the $H_2SO_4$ leaching solution with 47 g/L $Fe(Fe^{2+}/Fe^{3+}=1.03),$, 23.5 g/L Ni and 0.90M $H_2SO_4$ which leached from Fe-Ni alloy. Iron powder was used as a reducing agent for the cementation of Ni ion from the leaching solution. The reduction percentage of Ni ion was $17{\sim}20%$ by adding 4 times stoichiometric amount of iron powder at $60{\sim}80$. This may result from the fact that the cementation of Ni ion occurred after the reduction of $Fe^{3+}$ to $Fe^{2+}$ and the neutralization of $H_2SO_4$ with iron powder. The cementation process was proved to be unfeasible for the separation/recovery of Ni ion from the leaching solution including $Fe^{3+}$ as a major component. $Fe^{2+}$ present in the leaching solution was converted to $Fe^{3+}$ for solvent extraction of Fe ion using D2EHPA in kerosene as a extractant. The oxidation of $Fe^{2+}$ to $Fe^{3+}$ was completed by the addition of 1.2 times stoichiometric amount of 35% $H_2SO_4$. 99.6% $Fe^{3+}$ was extracted from the leaching solution (23.5 g/L $Fe^{3+}$) by 4 stages cross-current extraction using 20 vol.% D2EHPA in kerosene. $NiSO_4$ solution with 98.5% purity was recovered from the $H_2SO_4$ leaching solution of scrapped Fe-Ni alloy.

• Proceedings of the Korean Magnestics Society Conference
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• 2004.12a
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• pp.80-80
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• 2004

• Proceedings of the Korean Magnestics Society Conference
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• 2001.10a
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• pp.90-91
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• 2001

• Journal of Powder Materials
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• v.17 no.3
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• pp.203-208
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• 2010

A new High Frequency Induction Heating (HFIH) process has been developed to fabricate dense $Al_2O_3$ reinforced with Fe-Ni magnetic metal dispersion particles. The process is based on the reduction of metal oxide particles immediately prior to sintering. The synthesized $Al_2O_3$/Fe-Ni nanocomposite powders were formed directly from the selective reduction of metal oxide powders, such as NiO and $Fe_2O_3$. Dense $Al_2O_3$/Fe-Ni nanocomposite was fabricated using the HFIH method with an extremely high heating rate of $2000^{\circ}C/min$. Phase identification and microstructure of nanocomposite powders and sintered specimens were determined by X-ray diffraction and SEM and TEM, respectively. Vickers hardness experiment were performed to investigate the mechanical properties of the $Al_2O_3$/Fe-Ni nanocomposite.

• Journal of the Korean Chemical Society
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• v.37 no.10
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• pp.861-866
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• 1993

In general, the concentration of constituents can be more accurately measured in x-ray fluorescence analysis of Fe-Ni-Cr alloy by reducing and correcting the matrix effect with standard ingot samples. Because of the difficult the treatment at a high temperature in preparing the ingot samples of various concentrations, several standard specimens were prepared by mixing the powders of the metallic oxides in certain proportions and pressing them with a costant pressure. With the metallic oxide specimens thus obtained, different matrix coefficients were calculate from the intensities of the strength of the x-ray fluorescence and the concentration of the substances. It is found that effects of Fe and Cr on Ni are absorption rich and effects of Fe and Ni on Cr are enhancement rich, whereas Ni enhances Fe Fluorescence but Cr absorves Fe K${\alpha}$ line. And the x-ray fluorescence intensities were compared and analyzed between the metallic oxides and the ingot samples.

• Journal of the Korean Magnetics Society
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• v.24 no.2
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• pp.46-50
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• 2014

The crystallographic properties and cationic distribution of $M_{0.2}Fe_{2.8}O_4$ (M =Mn, Ni, Cu) and $Fe_3O_4$ thin films prepared by sol-gel method have been investigated by X-ray diffraction (XRD) and conversion electron M$\ddot{o}$ssbauer spectroscopy (CEMS). The ionic valence, preferred site, and hyperfine field of Fe ions of the ferrites could be obtained by analyzing the CEMS spectra. The $M_{0.2}Fe_{2.8}O_4$ films were found to maintain cubic spinel structure as in $Fe_3O_4$ with the lattice constant slightly decreased for Ni substitution and increased for Mn and Cu substitution from that of $Fe_3O_4$. Analyses on the CEMS data indicate that $Mn^{2+}$ and $Ni^{2+}$ ions substitute octahedral $Fe^{2+}$ sites mostly, while $Cu^{2+}$ ions substitute both the octahedral and tetrahedral sites. The observed intensity ratio $A_B/A_A$ of the CEMS subspectra of the samples exhibited difference from the theoretical value. It is interpreted as due to the effect of the M substitution for A and B on the Debye temperature of the site. The relative line-broadening of the B-site CEMS subspectra can be explained by the dispersion of magnetic hyperfine fields due to random distribution of M cations in the B sites.

• Journal of Welding and Joining
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• v.15 no.5
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• pp.46-55
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• 1997

This study has evaluated the liquation cracking behavior in the heat affected zone of several Ni base superalloys (Incoloy 825, Inconel 718 and Inconel 600). 304 and 310S austenitic stainless steels were also included for comparison. In addition, the mechanism of liquation cracking in the HAZ was postulated based on the extensive microstructural examinations with SEM, EDAX and TEM. The liquation cracking resistance of Ni base alloys was found to be far inferior to that of austenitic stainless steels. The liquation cracking of Incoloy 825 and Inconel 718 was believed to be closely related with the Laves-austenite(Ti rich in 825 and Nb rich in 718) and MC-austenitic eutectic phases formed along the grain boundaries by constitutional liquation and incipient melting under rapid welding thermal contraction. Further, liquation cracking resistance of the HAZ was dependent not only upon the type and amount of low melting phases but also on the grain size.

• Bulletin of the Korean Chemical Society
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• v.28 no.8
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• pp.1273-1279
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• 2007

The NiSO4 supported on Fe2O3 catalysts were prepared by the impregnation method. No diffraction line of nickel sulfate was observed up to 30 wt %, indicating good dispersion of nickel sulfate on the surface of Fe2O3. The addition of nickel sulfate to Fe2O3 shifted the phase transition of Fe2O3 (from amorphous to hematite) to higher temperatures because of the interaction between nickel sulfate and Fe2O3. 20-NiSO4/Fe2O3 containing 20 wt % of NiSO4 and calcined at 500 oC exhibited a maximum catalytic activity for ethylene dimerization. The initial product of ethylene dimerization was found to be 1-butene and the initially produced 1-butene was also isomerized to 2-butene during the reaction. The catalytic activities were correlated with the acidity of catalysts measured by the ammonia chemisorption method.