• Journal of Welding and Joining
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• 제15권4호
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• pp.116-125
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• 1997

Electron beam weldability of 9%Ni steels has been investigated to apply EBW to the construction of LNG storage tank. While mechanical properties of welded joints were satisfied by ASTM specification, impact energy of weld metal was as low as 27 - 55J at $-196^{\circ}C$. As the result of Ni wires inserted at the joint to be welded, Ni content of weld metal was increased to about 10%, resulting on the improvement of impact toughness to 110 ~ 120J at $-196^{\circ}C$. This improvement of impact toughness in weld metal was due to the formation of tempered martensite and retained austenite. Above results indicate that, if Ni content of weld metal was increased about 10% by Ni wires addition, electron beam welded 9%Ni steels weld metal had sufficient impact energy necessary for a LNG storage tank.

• Bulletin of the Korean Chemical Society
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• 제22권9호
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• pp.994-998
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• 2001

Ni, Fe and NiFe alloy thin films were electrodeposited at a polycrystalline Au surface using a range of electrolytes and potentials. Coulometry and EQCM were used for real-time monitoring of electroplating efficiency of the Ni and Fe. The plating efficiency of NiFe alloy thin films was computed with the aid of ICP spectrometry. In general, plating efficiency increased to a steady value with deposition time. Plating efficiency of Fe was lower than that of Ni at -0.85 and -1.0 V but the efficiency approached to the similar plateau value to that of Ni at more negative potentials. The films with higher content of Fe showed different stripping behavior from the ones with higher content of Ni. Finally, compositional data and real-time plating efficiency are presented for films electrodeposited using a range of electrolytes and potentials.

• 한국환경과학회지
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• 제13권8호
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• pp.711-719
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• 2004

The effect of nickel (Ni) on growth and some tolerance strategies with regard to heavy metal tolerance mechanism was investigated in radish (Raphanus sativus) seedlings. The protective effect of histidine on nickel stress conditions was also monitored. The seedling growth decreased with an increase in metal concentrations. The inhibitory effect was more pronounced in the root elongation than in the shoot elongation. Increasing Ni supply showed a progressive increase of Ni concentrations in the roots and shoots. Ni content was higher in the shoots than in the roots. In the presence of nickel, radish exhibited an antioxidative defense mechanism, as evidenced by the elevated malondialdehyde(MDA), showing that nickel is an efficient inducer of lipid peroxidation. Exposure of radish to elevated concentrations of nickel was accompanied by an increase in the proline content. Supplemental histidine in the presence of Ni ameliorated metal-induced growth inhibition and lipid peroxidation. Combinations of Ni and histidine resulted in a significant decline in proline content compared with Ni stress alone, indicating that histidine may provide protection against the adverse effect of Ni stress. From the results it is suggested that histidine is an efficient chelator by complexing metal ion within the plant and may playa role in nickel tolerance implicated in metal detoxification.

• 한국수소및신에너지학회논문집
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• 제8권1호
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• pp.11-21
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• 1997

$ZrV_{0.7}Mn_{0.5}Ni_{1.2}$ alloy is attractive for anode material in Ni/MH secondary battery because of its large hydrogen storage capacity in gas-solid reaction and long cycling durability in KOH electrolyte. In this work, in order to further improve the discharge performance of this alloy electrode, the alloy was annealed by optimal condition which is for 12 hours at $1000^{\circ}C$. The alloy annealed under optimal condition had higher rate capability and discharge capacity than as-cast one. The microstructure of the as-cast and annealed alloy was investigated by scanning electron microscopy and energy dispersive spectroscopy. Ni content in the matrix was increased, being this homogenized after annealing. Additionally, The measurement of the surface area by B.E.T. analysis showed that there was little difference as-cast and annealed alloy. Therefore, improvement in the rate capability of the annealed alloy is due to increase of Ni content in the matrix.

• 한국자기학회지
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• 제8권6호
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• pp.369-373
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• 1998

본 연구에서는 마그네트론 스퍼터링 법으로 제작한 Ni-Fe/NiO 이층 박에서, NiO 증착 중 Ar 압력에 따른 교환이 방성의 변화를 고찰하엿으며 이를 미세조작과 관련시켜 해석하고자 하였다. 낮은 Ar 압력에서 증착한 Ni-Fe/NiO 이층막은 우수한 교환이방성 특성을 나타내었으나 Ar 압력이 증가함에 따라 교환이방성은 급격하게 감소하였다. 낮은 Ar 압력에서 증착한 시편은 NiO와 Ni-Fe 계면에서 epitaxy 경향을 나타내었으며 그 계면은 평범하고 그 경계는 두렷하게 구분하였다. 그러나 높은 Ar 압력에서 증착한 시편은 NiO와 Ni-Fe의 경계가 뚜렷하게 구분되지 않고 그 계면 또한 평활하지 않았다. 한편 NiO의 조성은 Ar압력의 증가에 따라 산소의 조성이 점점 증가하였다.

• Journal of Magnetics
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• 제22권2호
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• pp.175-180
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• 2017

CoNi alloy films prepared from electrolytes with various concentrations of cobalt ions were studied in the paper. Influences of different cobalt ions concentrations on electrochemistry processes, components, microstructures, surface morphologies and magnetic properties of CoNi films were investigated. It was found that CoNi film plating was a kind of anomalous codeposition process. The percentage of cobalt content in CoNi films was higher than that of in the electrolyte. Moreover, with the rise of cobalt ions concentrations, the percentage of cobalt content in the samples increased gradually. CoNi films possessed crystal structures with four stronger diffraction peaks. However, CoNi films prepared from bath with higher cobalt ions possessed hcp structures which contributed to dendrite structures resulting in the increase of coercivity.

• Composites Research
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• 제28권6호
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• pp.361-365
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• 2015

The influence of MWCNTs on fracture toughness properties of MWCNTs/Nickel-Pitch Fibers/epoxy composites (MWCNTs/Ni-PFs/epoxy) was investigated according to MWCNTs content. Nickel-Pitch-based carbon fibers (Ni-PFs) were prepared by electroless nickel-plating. The surface properties of Ni-PFs were determined by scanning electron microscopy (SEM) and X-ray photoelectron spectrometry (XPS). The fracture toughness of MWCNTs/Ni-PFs/epoxy was assessed by critical stress intensity factor ($K_{IC}$) and critical strain energy release rate ($G_{IC}$). From the results, it was found that the fracture toughness properties of MWCNTs/Ni-PFs/epoxy were enhanced with increasing MWCNTs content, whereas the value decreased above 5 wt.%. MWCNTs content. This was probably considered that the MWCNTs entangled with each other in epoxy due to an excess of MWCNTs.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2004년도 춘계학술대회 논문집
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• pp.129-135
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• 2004

This study was to evaluate the effect of carbon content on metallic change and fatigue characteristics with Fe-29% Ni-17% Co, low heat expansion alloy, widely using electronic components, precision machines, and sealing with glass and metal etc. The steels were fabricated with variation of carbon content, 0, 0.03, 0.06, 0.1, and 0.20% with VIM and tensile test and fatigue test were performed to achieve the above purpose. The more carbon content, the higher hardness value and yield strength. But elongation of 0.03%C, 0.06%C, and 0.10%C specimen decreased about 2.2%, 1.5% and 0.8% respectively mote than that of the base metal. Especially the strength and elongation of 0.20%C specimen increased simultaneously about 14.4% and 7.5%. Fatigue life of 0.03%C specimen decreased but the more carbon content, the higher fatigue life over 0.06% carbon content more than that of base metal.

• 한국표면공학회지
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• 제20권4호
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• pp.144-153
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• 1987

In the case of dipping the Ni-Resist cast iron into molten aluminum with iron content, the thickness of intermetallic compound was remarkably increased with increasing iron content. The thickness was shown by following equation in the range of 1-3% iron content; $x=22.5t^{1/2}+4.47{\cdot}t{\cdot}(Fe%)$. where, x is thickness(${\mu}m$), t the time (minute), Fe% the iron w/o. When the Ni-Resist cast iron was dipped into the molten aluminum containing zinc content, the intermetallic compound thickness was also increased with increasing zinc contents. And thickness was represented by the following equation in the range of 2-10% zinc content; $x=3.46t^{1/2}+0.27{\cdot}t{\cdot}(Zn%)$. However, in the case of dipping the Ni-resist cast iron into molten aluminum with silicon content, the thickness of intermetallic compound was decreased with increasing silicon content, as shown in the following equation; $x=7.17t^{1/2}-0.15{\cdot}t{\cdot}(Si%)$. The intermetallic compound formed onto Ni-Resist cast iron was identified to be $FeAl_3\;and\;Fe_3Al$. As the result of hardness measurement, the peak hardness appeared in the intermetallic compound at near interface of the cast iron and the compound.

• 대기
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• 제22권4호
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• pp.465-472
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• 2012

Using various observed data, we examined the evolution of tropical Pacific sea surface temperature (SST) during 2011-2012, with focusing on the development of 2012 El Ni$\tilde{n}$o. It is observed that a La Ni$\tilde{n}$a event during 2011 was followed by a moderate El Ni$\tilde{n}$o during 2012 summer. The 2012 summer El Ni$\tilde{n}$o initiated near the west coast of South America on February 2012, and continued to expand westward till August. Given this evolutionary pattern, the 2012 summer El Ni$\tilde{n}$o can be categorized as 'Eastern Pacific (EP) El Ni$\tilde{n}$o' because Ni$\tilde{n}$o-3 index is greater than Ni$\tilde{n}$o-4 index, and it may be the first well-defined EP El Ni$\tilde{n}$o since 2001. On February 2012, this event was initiated mainly by the local air-sea interaction, and at the same time the ocean heat content was accumulated over the tropical western Pacific due to the easterly wind anomaly over the tropical western Pacific. Then, the accumulated heat content slowly propagates to the tropical eastern Pacific, which attributes to maintain El Ni$\tilde{n}$o state during 2012 summer. After August, the positive SST anomaly over the equatorial eastern Pacific decays possibly due to the exhausted heat content and the weakening of air-sea interaction, but the weak positive SST anomaly over the central Pacific remains till now (2012 November).