• Journal of Biomedical Engineering Research
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• v.25 no.5
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• pp.383-389
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• 2004

A commercially pure Ti(CP-Ti) and Ti-25wt％Pd alloy for dental applications were cast into a phosphate-bonded Al$_2$ $O_3$/ $SiO_2$ investment mold and the surface of the casting specimens were investigated by means of SEM/EDS, XRD and XPS. The addition of 25wt％Pd in CP-Ti showed a moderate mold reaction owing to the considerable lowering of melting point. XRD analysis of the investment after burn-out treatment revealed that it consisted essentially of $SiO_2$, Al$_2$ $O_3$, P$_2$O$\_$5/, Mg$_3$(P $O_4$)$_2$, AlP $O_4$, Mg$_2$ $SiO_4$, MgAl$_2$ $O_4$ The mold reaction products were Ti$\_$5/Si$_3$ and Ti $O_2$ in case of CP-Ti casting and Ti $O_2$ and SiO$\_$x/ in case of Ti-25wt％ Pd casting.

• Korean Journal of Materials Research
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• v.15 no.4
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• pp.281-284
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• 2005

Room and high temperature deformation behaviors of Cu-Zr-Ti-Pd bulk metallic glasses produced by copper mold casting were investigated. The addition of Pd was shown to enhance the glass forming ability and thermal stability of Cu-Zr-Ti base bulk metallic glass. The compressive strength of $Cu_{55}Zr_{30}Ti_{10}Pd_5$ bulk metallic glass was 2230 MPa with 1.8 plastic strain. The stress overshoot and yield drop phenomenon were observed below $487^{\circ}C$ and a drastic decrease in the flow stress was observed at $487^{\circ}C$. The stress overshoot is thought to be associated with stress-induced structural relaxation.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2010.11a
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• pp.433-434
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• 2010

• Membrane Journal
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• v.22 no.1
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• pp.1-7
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• 2012

We make a studyof the hydrogen permeability and chemical stability of $Nb_{56}Ti_{23}Ni_{21}$ metal alloy membrane. For this purpose, we produced the $Nb_{56}Ti_{23}Ni_{21}$ membrane which has 10 mm diameter and 0.5 mm thick, and experiment the hydrogen transport properties under two kinds of feed gas ($H_2$ 100%; $H_2$ 60% + $CO_2$ 40%) at $450^{\circ}C$C with variation of absolute pressure.The maximum hydrogen permeation flux was $5.58mL/min/cm^2$ in the absolute pressure 3 bar under pure hydrogen. And each case of feed gases about gas composition, the permeation fluxes were satisfied with Sievert's law, and the hydrogen permeation flux decreased with decrease of hydrogen partial pressure irrespective of temperature and pressure. After permeation test, we experiment the stability and durability of $Nb_{56}Ti_{23}Ni_{21}$ alloy membrane for carbon dioxide by XRD analysis.

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

• The Journal of Korean Academy of Prosthodontics
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• v.41 no.1
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• pp.1-19
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• 2003

The surface of metals should be as smooth as possible for optimum comfort, oral hygiene, low plaque retention, and resistance to corrosion. In this study five specimens of each precious metal(type III gold alloy, ceramic gold alloy, and Ag-Pd alloy) were divided into five groups according to finishing and polishing procedures : group 1(sandblaster), group 2(group 1+stone), group 3(group 2+brown rubber), group 4(group 3+green rubber), and group 5(group 4+rouge). Six specimens of each non-precious metal(Co-Cr alloy, Ni-Cr alloy, and Co-Cr-Ti alloy) were divided into six groups: group 1(sandblaster), group 2(group 1+hard stone), group 3(group 2+electrolytic polisher), group 4(group 3+brown hard rubber point), group 5(group 4+green hard rubber point), and group 6(group 5+rouge). Considering factors affecting the rate of abrasion, the same dentist applied each finishing and polishing procedure. In addition, the surface roughness of enamel, resin, and porcelain was evaluated. The effect of finishing and polishing procedures on surface roughness of precious and non-precious metals, enamel, resin, and porcelain was evaluated by means of Atomic Force Microscope(AutoProbe CP. Park Scientific Instruments, U.S.A.) that can image the three dimensional surface profile and measure average surface roughness values of each sample at the same time. The obtained results were as follows : 1. According to finishing and polishing procedures, the surface roughness of type III gold alloy, ceramic gold alloy, and Ag-Pd alloy was decreased in the order of group 1, 2, 3, 4, and 5 (P<0.01). 2. According to finishing and polishing procedures. the surface roughness of Co-Cr alloy, Ni-Cr alloy, and Co-Cr-Ti alloy was decreased in the order of group 1, 2, 3, 4, 5, and 6 (p<0.01). 3. There was not statistically significant difference in the surface roughness among three metals of precious metals in group 1 but was significant difference in group 2, 3, 4, and 5 (P<0.05). 4. There was not statistically significant difference in the surface roughness among three metals of non-precious metals in all groups. 5. When the surface roughness of the smoothest surface of each metal, enamel. porcelain, and resin was compared, porcelain was the smoothest and the surface roughness was decreased in the order of Ni-Cr alloy. Co-Cr alloy. Co-Cr-Ti alloy, resin. Ag-Pd alloy, ceramic gold alloy type III gold alloy, and enamel (P<0.01). The results of this study indicate that the finishing and polishing procedures should be carried out in a logical, systematic sequence of steps and the harder non-precious metals may be less resistance to abrasion than are the softer precious metals.

• Analytical Science and Technology
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• v.9 no.2
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• pp.192-197
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• 1996

The purpose of this study is to develop new V-free Ti alloys which have good mechanical properties and corrosion resistance. Although pure Ti has an excellent biocompatibility and corrosion resistance in body, it is inferior to Ti alloys in mechanical properties, and Ti-6Al-4V which has good mechanical properties was known to be cytotoxic due to the alloying element V. New Ti based alloys which do not contain the toxic metallic components were developed by the alloy design technique. Their corrosion and mechanical characteristics were compared with pure Ti and Ti-6Al-4V in this study. The results showed that Ti-20Zr-3Nb-3Ta-0.2Pd-1In and Ti-5AI-4Zr-2.5Mo exhibit good mechanical oroperties and an excellent corrosion resistance in 0.9% NaCl solution.

• Proceedings of the Korean Vacuum Society Conference
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• 1999.07a
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• pp.29-29
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• 1999

The synthesis of layered structures on the nanometer scale has become essential for continued improvements in the operation of various electronic and magnetic devices. Abrupt metal-metal interfaces are desired for applications ranging from metallization in semiconductor devices to fabrication of magnetoresistive tunnel junctions for read heads on magnetic disk drives. In particular, characterizing the interface structure between various transition metals (TM) and aluminum is desirable. We have used the techniques of MeV ion backscattering and channeling (HEIS), x-ray photoemission (ZPS), x-ray photoelectron diffraction(XPD), low-energy ion scattering (LEIS), and low-energy electron diffraction(LEED), together with computer simulations using embedded atom potentials, to study solid-solid interface structure for thin films of Ni, Fe, Co, Pd, Ti, and Ag on Al(001), Al(110) and Al(111) surfaces. Considerations of lattice matching, surface energies, or compound formation energies alone do not adequately predict our result, We find that those metals with metallic radii smaller than Al(e.g. Ni, Fe, Co, Pd) tend to form alloys at the TM-Al interface, while those atoms with larger atomic radii(e.g. Ti, Ag) form epitaxial overlayers. Thus we are led to consider models in which the strain energy associated with alloy formation becomes a kinetic barrier to alloying. Furthermore, we observe the formation of metastable fcc Ti up to a critical thickness of 5 monolayers on Al(001) and Al(110). For Ag films we observe arbitrarily thick epitaxial growth exceeding 30 monolayers with some Al alloying at the interface, possible driven by interface strain relief. Typical examples of these interface structures will be discussed.

• Transactions of the Korean hydrogen and new energy society
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• v.16 no.3
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• pp.244-252
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• 2005

It is very interesting and important in the academic point of view and in practical use the hydrogen-induced phase separation(HIPS) which appears during hydrogen heat treatment. Since hydrogen can be removed very fast by pumping it out the hydrogen-induced new lattice phase which can not be obtained without hydrogen can be preserved as meta-stable state. In this study it has been investigated whether the HIPS appear in Pd-Al, Pd-Co, Pd-Cr, Pd-Ti, Pd-V and Pd-Zr alloys and discussed thermodynamic representation of the HIPS. The Pd alloys were arc-melted under argon atmosphere and remelted 4 or 5 times for homogenization. The alloys were annealed at 600$^{\circ}C$ under vacuum for 24 hrs and then subjected to pressure-composition isotherm measurements at 100$^{\circ}C$. The hydrogen heat treatment(HHT) of samples was carried out at 600$^{\circ}C$ under hydrogen pressure of 70 bar for 6 days and PC isotherms at 100$^{\circ}C$ were measured. By comparing the PC isotherms measured before and after HHT, occurrence of phase separation was determined. The experimental results showed that the HIPS appeared only in Pd-0.05Co alloy. For Pd-Co alloys with various composition the PC isotherms were measured. By adopting Park-Flanagan model for ternary thermodynamics the Gibbs free energy change for Pd-Co-H solid solution was calculated and subsequently with this the HIPS in Pd-Co alloy was explained fairly.

• Journal of Powder Materials
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• v.11 no.3
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• pp.193-201
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• 2004

1960년 Au-Si계 합금에서 처음으로 비정질상이 급속 응고법에 의해 보고된 이래/sup 1)/ 지난 40년 간 많은 합금계에서 비정질상이 보고되어졌다. 대표적으로 Fe-, Ni-, Co기 합금 등 많은 합금계에서 비정질상이 보고되었으나, 비정질상의 형성을 위해서는 약 105 K/s이상의 높은 냉각속도를 필요로 하였다. 1980년대 수백 K/s의 낮은 냉각속도 하에서도 비정질상이 형성될 수 있는 다원계 합금(multi-component alloy)이 Mg-Ln-(Ni, Cu, Zn), Ln-Al-TM 합금에서 보고되어 졌으나 많은 관심을 받지 못하다가 1993년 Zr-Ti-Ni-Cu-Be 합금에서 수 ㎝ 크기의 비정질합금 제조가 보고되면서 전 세계적으로 많은 관심을 받게 되었다. Zr-Ti-Ni-Cu-Be계 벌크 비정질 합금이 보고된 후 Zr-(Nb,Pd)-Al-TM, Pd-Cu-Ni-P, Fe-Co-Zr-Mo-W-B, Ti-Zr-Ni-Cu-Sn등 여러 합금계에서 벌크 비정질 합금이 보고되었다. (중략)