• Journal of Korea Foundry Society
• /
• v.14 no.5
• /
• pp.429-437
• /
• 1994

Influence of interfacial structure between matrix and particle in A356/coated SiC composite fabricated by squeeze casting method was studied. Experimental variables are types of coated metallic film on SiC particles such as Cu, Ni-P, and applied pressure for squeeze casting. It was found that coating treatment on SiC particles improves the wetting of liquid A356 alloy on SiC particles. SiC particle distribution is very homogeneous in A356 matrix alloy which is fabricated by squeeze casting. Analysing the surface morphology of fractured A356/coated SiC, it was concluded that metallic thin film by coating treatment on SiC particle improves the interfacial bonding between particle and matrix, and so does on mechanical properties such as tensile strength. However, there was on significant difference in hardness between those composite made of as-received SiC particle and coated SiC particle.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2005.07a
• /
• pp.31-32
• /
• 2005

Ge 농도가 30%인 SiGe 위에 Ni-Pd 합금을 이용한 새로운 Ni-Germanosilicide의 방법을 제안하여 열안정성 향상에 대해 연구하였다. 새롭게 제안한 Ni-Pd 합금을 이용하여 3 가지 구조 (Ni-Pd, Ni-Pd/TiN, Ni-Pd/Co/TiN) 중 Cobalt 다층구조를 사용한 구조 (Ni-Pd/Co/TiN)가 면저항이 가장 낮고 안정한 silicide 특성을 갖는 것을 나타냈으며, 고온열처리 $700^{\circ}C$, 30분에서도 낮고 안정한 면저항 특성을 유지시켜 열안정성을 개선하였다.

• Journal of Powder Materials
• /
• v.26 no.5
• /
• pp.389-394
• /
• 2019

In the present study, we have investigated the effect of sintering process conditions on the stability of the austenite phase in the nanocrystalline Fe-5wt.%Mn-0.2wt.%C alloy. The stability and volume fraction of the austenite phase are the key factors that determine the mechanical properties of FeMnC alloys, because strain-induced austenite-martensite transformation occurs under the application of an external stress at room temperature. Nanocrystalline Fe-5wt.%Mn-0.2wt.%C samples are fabricated using the spark plasma sintering method. The stability of the austenite phase in the sintered samples is evaluated by X-ray diffraction analysis and hardness test. The volume fraction of austenite at room temperature increases as the sample is held for 10 min at the sintering temperature, because of carbon diffusion in austenite. Moreover, water quenching effectively prevents the formation of cementite during cooling, resulting in a higher volume fraction of austenite. Furthermore, it is found that the hardness is influenced by both the austenite carbon content and volume fraction.

• Korean Journal of Materials Research
• /
• v.7 no.3
• /
• pp.234-243
• /
• 1997

The crystal structure of arc melted $ZrV_{x}Mn_{1-x}Ni_{1.0},\;ZrV_{x}Mn_{0.8-x}Ni_{1.2},\;ZrV_{x}Mn_{0.6-x}Ni_{1.4}$ alloys which are known to have AB2 type Laves structure was investigated. They had mixed phases of C14 and C15. The radius ratio ($r_{A}/r_{B}$) of atoms in A site to that of B site was found to be an important parameter in explaining the omposition dependence of the crystal structure The C15 structure showed a linear increase with the ratio in as-cast conditions. However, the annealed alloys revealed a definite ratio at which the stability of both phases are divided distinctly. The composition of the alloys could be closely controlled by maintaining the argon pressure in the chamber over 1 arm during arc melting. In contrast, the alloy ingot melted in VIM showed a significant loss of hln.

• Journal of Powder Materials
• /
• v.13 no.4 s.57
• /
• pp.285-289
• /
• 2006

Co-Fe-Ni-B-Si-Cr based amorphous strips containing nitrogen were manufactured via melt spinning, and then devitrified by crystallization treatment at the various annealing temperatures of $300^{\circ}C{\sim}540^{\circ}C$ for up to 30 minutes in an inert gas $(N_2)$ atmosphere. The microstructures were examined by using XRD and TEM and the magnetic properties were measured by using VSM and B-H meter. Among the alloys, the amorphous ribbons of $Co_{72.6}Fe_{9.8}Ni_{5.5}B_{2.4}Si_{7.1}Cr_{2.6}$ containing 121 ppm of nitrogen showed relatively high saturation magnetization. The alloy ribbons crystallized at $540^{\circ}C$ showed that the grain size of $Co_{72.6}Fe_{9.8}Ni_{5.5}B_{2.4}Si_{7.1}Cr_{2.6}$ alloy containing 121 ppm of nitrogen was about f nm, which exhibited paramagnetic behavior. The formation of nano-grain structure was attributed to the finely dispersed Fe4N particles and the solid-solutionized nitrogen atoms in the matrix. Accordingly, it can be concluded that the nano-grain structure of 5nm in size could reduce the core loss within the normally applied magnetic field of 300A/m at 10kHz.

• Polymer(Korea)
• /
• v.25 no.2
• /
• pp.218-225
• /
• 2001

The electroless plating of a metallic nickel on PAN-based carbon fiber surfaces was carried out to improve mechanical interfacial properties of the carbon fiber/epoxy resin composites which were unidirectionally fabricated by a prepregging method. In this work, the influence of Ni-P alloy concentration showing brittle-to-ductile transition was investigated on interlaminar shear strength (ILSS) and impact strength of the composites. The surface properties of carbon fibers were also measured by X-ray photoelectron spectroscopy (XPS). As the result, the $O_{ls}$ /$O_{ls}$ ratio or Ni and P amounts were increased with increasing electroless nickel plating time but the ILSS were not significantly improved. However, the impact properties was significantly improved in the presence of Ni-P alloy in the carbon fiber surface, resulting in an increase of the ductility of the composites.

• Korean Journal of Materials Research
• /
• v.11 no.8
• /
• pp.666-670
• /
• 2001

To improve the corrosion resistance of separator wet-seal area which is the barrier of commercialization of molten carbonate fuel cell(MCFC), Ni/Y/Al coating layer was fabricated by Ni electroplating and Y, Al e-beam PVD on AISI 316L stainless steel. NiAlY alloy coating layer was formed by heat treatment in reduction atmosphere at $800^{\circ}C$ for 5hr. Immersion test in molten carbonate salt at $650^{\circ}C$ was performed on as- received AISI 316L stainless steel and NiAlY coated specimen. According to cross sectional SEM/EDS observations, corrosion resistance of separator wet-seal area was improved by formation of dense oxide layers of Al and Y.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.19 no.8
• /
• pp.403-409
• /
• 2018

Inconel 713C which of a commercial Ni super alloy have the composition of 70 % Ni, 12 % Cr, 6 % Al and 4 % Mo. Mo is very expensive and have some economic value to recover in the alloy. In this study, liquid-liquid exraction(solvent extraction and stripping) has been performed to separate Mo from the synthetic leaching solution of spent Inconel 713C alloy and prepare to Mo powder by dying, evaporation and heat treatment. The experiments were conducted by using synthetic leaching solution which was prepared $NaMoO_4$ $2H_2O$ by dissolved in distilled water. Alamine336 and Cyanex272 dissolved in kerosene were used as extractants. The extraction percentage of Mo by Alamine336 is 99 % in the condition of the range of pH 1 to 4 and 1 % of concentration of Alamine336. The stripping solutions are used by HCl, $H_2SO_4$ and $HNO_3$ solutions and the concentrations were controlled by distilled water. The concentrations of HCl, $H_2SO_4$ and $HNO_3$ as stripping solutions are increased, the stripping percentages of Mo are increased and the stripping percentage of Mo by $HNO_3$ is higher than other stripping solutions. After liquid-liquid extraction and heat treatment, $MoO_3$ powder which of the purity of 97.5 % was prepared.

• Journal of the Korean Electrochemical Society
• /
• v.11 no.4
• /
• pp.289-296
• /
• 2008

Electrochemical studies were performed by a half-cell test for the nickel hydroxide (cathode) and hydrogen storage alloy(anode) electrodes for the sealed Ni-MH batteries applicable to industrial use. The electrodes were fabricated and checked a charge efficiency and an internal pressure of the battery during charge-discharge cycling. In order to reduce the internal pressure of the sealed Ni-MH battery, cyclic voltammetry (CV) were performed on the electrodes of nickel hydroxide(cathode) and hydrogen storage alloy(anode), respectively. The results of the test showed clearly the oxidation/reduction and oxygen evolution reaction in a nickel hydroxide electrode and the hydrogenation behavior of a hydrogen storage electrode. The sealed Ni-MH battery of 130Ah was fabricated by using nickel hydroxide of a high over-voltage for an oxygen gas evolution and hydrogen storage alloy of a good performance for activation The battery showed a good characteristics such as a high charge efficiency of 98% at 1 C charge current, a low level internal pressure of 4 atm on a continuous over-charging and a large preservation capacity of 95% at 400 cycle.

• Proceedings of the Korean Society for Technology of Plasticity Conference
• /
• 2007.10a
• /
• pp.143-145
• /
• 2007

The correlation between crystallization and deformation behavior in the supercooled liquid region (SLR) of a $Cu_{54}Ni_{6}Zr_{22}Ti_{18}$ bulk metallic glass (BMG) alloy is investigated by compression tests, differential scanning calorimetry (DSC), electron energy loss spectrometry (EELS) and high resolution transmission electron microscopy (HRTEM). In the SLR, This BMG alloy was strongly depended on the deformation temperature and the alloy exhibits important change in deformation behavior after a given time which is directly connected to the development of crystallization. Compressive stress impeded decomposition and consequently retarded forming of nano-crystal, which led to enlarge the homogeneous deformation region of the BMG alloy in SLR during compression test.