• The korean journal of orthodontics
• /
• v.14 no.2
• /
• pp.241-248
• /
• 1984

The mechanical properties of Cr-Ni alloy of austenitic stainless steel and Co-Cr alloy orthodontic wires were studied in tension. The wires (0.018 inch) were tested in the as-manufactured and heat-treated conditions. Instron type tension testing machine was used for this study. Mean values and standard deviations were computed. The results were as follows; 1. The Cr-Ni orthodontic wires of austenitic stainless steel are generally superior than the Co-Cr orthodontic wires in ultimate tensile strength, In the elongation, however, Co-Cr orthodontic wire are superior than Cr-Ni orthodontic wires. 2. Increase in the degree of strength by heat treatment are more clearly shown in Co-Cr orthodontic wires than Cr-Ni orthodontic wires. And the elongation is decreased by heat treatment in both case. 3. The changes of the degree of strength by cooling method we not clearly shown, but in Cr-Ni orthodontic wires, air cooling are more effective, in Co-Cr orthodontic wires, cooling effect are scarcely shown.

• Proceedings of the Korean Institute of Surface Engineering Conference
• /
• 2017.05a
• /
• pp.124-124
• /
• 2017

Fe-Ni-Co 합금 박막(<$100{\mu}m$)을 황화물계 용액에서 전주공정으로 제조하였다. XRF로 측정한 박판의 평균 조성은 Fe-34 wt.% Ni-3 wt.% Co 이다. AFM으로 측정한 표면 조도는 35.2 nm 이다. 표면의 나노 경도는 평균 5.4 GPa 이었다. Oliver 모델을 적용한 구리 박막의 탄성하강강성도는 약 75 이었다. Alekhin 모델을 적용한 구리 박막의 마찰계수, 피로한계는 각각 0.134, 0.027 이었다. 유한요소법으로 평가한 Berkovich 형 나노압침선단의 하중분포를 이차원 선형 및 비선형 해석하면 1 [mN]의 정적하중을 가한 Fe-Ni-Co 박막은 약 576 [mN]로 예측되었다. 압침선단의 하중집중정도는 표면탐침현미경으로 관찰한 압흔의 변형정도와 유사한 경향을 보였다.

• Journal of Powder Materials
• /
• v.12 no.2 s.49
• /
• pp.151-158
• /
• 2005

Porous graphite was synthesized by removal of template in HF after pyrolysis of pyrolyzed fuel oil (PFO) at $900^{\circ}C$ using the template of Co or Ni intercalated magadiite. Porous graphite had a plate structure like template, and d-spacing value of about 0.7 nm. The extent of crystallization of porous graphite was dependent on the contents of Co or Ni intercalated in interlayer. It can be explained that the metal such as Co and Ni acts as a promotion catalyst for graphite formation. Porous graphite shows the surface area of $328\sim477 m^2/g$.

• Bulletin of the Korean Chemical Society
• /
• v.7 no.2
• /
• pp.102-105
• /
• 1986

Samples with the nominal composition of $Co_{9-x}M_xS_8$(M = Ni, Rh, Ru, and Fe) were prepared, and their magnetic properties were measured. X-ray diffraction analysis showed that small amount of the elements Ni, Rh, and Fe could be incorporated into $Co_9S_8$ forming a homogeneous ${\pi}$-phase, whereas the Ru-incorporated sample could not be prepared in a single phase. The lattice parameter was observed to increase as other elements were incorporated into $Co_9S_8$. Samples incorporated with the elements of Ni, Rh, and Ru showed Pauli-paramagnetism while the Fe-incorporated sample exhibited weak ferromagnetism. The values of magnetic susceptibility for the Ni, Rh, Ru-incorporated samples were nearly the same as that of pure $Co_9S_8$.

• Bulletin of the Korean Chemical Society
• /
• v.33 no.12
• /
• pp.3993-3997
• /
• 2012

Three-dimensional porous nickel foam was used as a current collector to prepare a Co-Ni oxide/Ni foam electrode for a supercapacitor. The synthesized Co-Ni oxide was proven to consist of mixed oxide phases of $Co_3O_4$ and NiO. The Co-Ni oxide/Ni foam electrode prepared was characterized by morphological observation, crystalline property analysis, cyclic voltammetry, and impedance spectroscopy. Cyclic voltammetry for the electrode showed high specific capacitances, such as 936 F $g^{-1}$ at 5 mV $s^{-1}$ and 566 F $g^{-1}$ at 200 mV $s^{-1}$, and a comparatively good cycle performance. These improved results were mainly due to the dimensional stability of the nickel foam and its high electrical contact between the electrode material and the current collector substrate.

• Korean Journal of Environment and Ecology
• /
• v.12 no.3
• /
• pp.271-278
• /
• 1998

Heavy metal concentrations in rocks and soils from serpentinite(SP) and in plants (Pinus densiflora: PD and Pinus rigida: PR) were examined at Baekdong mine in Hongsung, Chungnam. Parent rocks were compared with amphibole schist(AS) and gneiss(GN) and plants divided the above grounds and roots were examined, respectively. In rocks, Ni, Cr, Co, Fe concentrations in SP were higher than those in AS and GN. The concentrations of top soils had the similar differences to their rocks; especially Ni, Cr, Co, Fe concentrations were the highest in SP, Zn and Sc concentrations, however, were the highest in AS. Average Ni, Cr, Co, Au, As, Sb, W concentrations of PD were the highest in SP and especially Ni, Cr, Co concentrations were accorded with changes of rocks and top soils. Zn and Sc concentrations in AS were higher and Fe and Mo concentrations in GN were higher than those in SP. Compared with two plants in the same serpentinite sites, most elements of PR were higher than those of PD. Therefore, these suggested PR absorbed much heavy metal than PD. Most element concentrations of roots in two plants and three rocks were higher than those of the above ground. Relative ratios (average plant concentration/soil concentration) of Ni, Cr, Co, Zn, Sc, Fe in AS and GN were higher than those of SP. Especially, relative ratios of most elements except Zn in GN were the highest.

• Korean Journal of Metals and Materials
• /
• v.49 no.2
• /
• pp.167-173
• /
• 2011

Nickel cobalt ferrite($Ni_{0.5}Co_{0.5}Fe_2O_4$) powder was prepared through the ceramic route by the calcination of a stoichiometric mixture of NiO, CoO and $Fe_2O_3$ at $1100^{\circ}C$. The pressed pellets of $Ni_{0.5}Co_{0.5}Fe_2O_4$ were isothermally reduced in pure hydrogen at $800{\sim}1100^{\circ}C$. Based on the thermogravimetric analysis, the reduction behavior and the kinetic reaction mechanisms of the synthesized ferrite were studied. The initial ferrite powder and the various reduction products were characterized by X-ray diffraction, scanning electron microscopy, reflected light microscope and vibrating sample magnetometer to reveal the effect of hydrogen reduction on the composition, microstructure and magnetic properties of the produced Fe-Ni-Co alloy. The arrhenius equation with the approved mathematical formulations for the gas solid reaction was applied to calculate the activation energy($E_a$) and detect the controlling reaction mechanisms. In the initial stage of hydrogen reduction, the reduction rate was controlled by the gas diffusion and the interfacial chemical reaction. However, in later stages, the rate was controlled by the interfacial chemical reaction. The nature of the hydrogen reduction and the magnetic property changes for nickel cobalt ferrite were compared with the previous result for nickel ferrite. The microstructural development of the synthesized Fe-Ni-Co alloy with an increase in the reduction temperature improved its soft magnetic properties by increasing the saturation magnetization($M_s$) and by decreasing the coercivity($H_c$). The Fe-Ni-Co alloy showed higher saturation magnetization compared to Fe-Ni alloy.

• Proceedings of the Korean Magnestics Society Conference
• /
• 1996.05a
• /
• pp.24-25
• /
• 1996

• Proceedings of the Korean Society of Laser Processing Conference
• /
• 1999.11a
• /
• pp.5-6
• /
• 1999

• Polymer(Korea)
• /
• v.25 no.6
• /
• pp.765-773
• /
• 2001

In In order to remove harmful trace elements such as $Co^{2+}$, $Ni^{2+}$ , $Cr_2O_7\;^{2-}$ from water, we synthesized AN-co-(MMA/IA) according to various mole ratio of monomers and spun by wet-spinning. And multi-functional PAN ion exchangers were prepared by hydrolysis. We observed structure, degree of functionalization, ion exchange capacity, distribution coefficient and mechanical properties for ion exchanger. Anion exchange capacity decreased in 4.5 ~ 4.2 meq/g with increasing of IA content and cation exchange capacity increased in 1.8 ~ 2.2 meq/g. Tensile strength of the ion exchanger increased up to 0.008 mol% IA content and appeared maximum value by 216$kg/cm^2$Distribution coefficient for AN-co-(MMA/IA) ion exchanger appeared maximum value for Co(II), Ni(II) in pH 5-6 range and for Cr(III) in pH 3-4 range. And the adsorption capacity was in the order of Cr(III) > Co(II) > Ni(II) for multicomponent in continuous process.