• Journal of Surface Science and Engineering
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• v.51 no.3
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• pp.139-148
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• 2018

In this study, surface analysis of Ni-Cr and Co-Cr alloys with addition of Ti and Mo for dental CAD/CAM use has been researched experimentally. The surface characteristics of the alloys were examined by Vickers hardness test, bonding strength test, surface roughness test, field-emission scanning electron microscopy, energy dispersive X-ray spectroscopy, and X-ray diffraction spectroscopy. The shrinkage of the sintered Ni-Cr alloy alloy was slightly larger than that of Ni-Cr-Ti alloy, and larger than Co-Cr alloy. Also, the addition of Mo showed a tendency to decrease shrinkage somewhat. From the result of XRD analysis, NiCr, $Ni_3Cr$ and $Ni_3Ti$ were observed in the sintered Ni-13Cr-xTi and Ni-13Cr-xMo alloys. In addition, ${\sigma}-CrCo$, $Co_2Mo_3$ and $TiCo_2$ were formed in the sintered Co-Cr-xTi and Co-Cr-xMo alloys. Surface hardness of Ti and Mo added alloy was higher than those of Ni-Cr and Co-Cr alloy. The bond strength between sintered alloy and porcelain was $16.1kgf/mm^2$ for Ni-13Cr alloy, $17.8kgf/mm^2$ for Ni-13Cr-5Ti alloy, and $8.2kgf/mm^2$ for Ni-13Cr-10Ti alloy, respectively.

• Journal of the Korean Magnetics Society
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• v.4 no.1
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• pp.20-24
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• 1994

The read/write characteristics of CoCr/NiFe double layered media are strongly affected by the magnetic properties of NiFe magnetic soft layer as well as those of CoCr recording layer. Modification of the permalloy layer by NiFe/Ge multilayer scheme resulted in the higher recording sensitivity and the higher reproduced voltage of CoCr/NiFe medium and this is attributed to the higher permeability of the back layer and high perpendicular anisotropy of the CoCr recording layer. Although higher permeability of back layer results in higher recording sensitivity, the increment of the reproduced voltage was not remarkable, which can be confirmed in the FEM numerical analysis. On the contrary, peak shift characteristics of the CoCr/NiFe medium with the NiFe multi back layer was deteriorated compared to that of the CoCr/NiFe medium with NiFe single back layer. Insertion of ferromagnetic thin CoZrNb intermediate layer between CoCr and NiFe layer was effective to ensure large reproduced voltage and low peak shift. These recoridng characteristics were also discussed in connection with microstructural characteristics.

• Journal of Surface Science and Engineering
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• v.50 no.3
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• pp.164-169
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• 2017

Ni-Cr-X ternary interlayers were investigated to improve the adhesion of Cu/Ni-Cr/Polyimide flexible copper clad laminates. The ternary compounds are sputtered Ni-Cr-X films (where X is one of Nb, V, Mo, or Ti), and the effect of third elements on the adhesion was evaluated and investigated chemically and mechanically. The feel strength was higher in the order of Ni-Cr-Nb > Ni-Cr-V > Ni-Cr > Ni-Cr-Mo > Ni-Cr-Ti. Nb, which has a comparable standard electrode potential to Cr, increased the adhesion, while Ti, with a low standard electrode potential, degraded the adhesion. The Ni-Cr-Nb interlayer was amorphous, while Ni-Cr-Ti was partially crystalline. The similar morphology structure of the Ni-Cr-Nb interlayer with polyimide resulted in a better adhesion.

• Journal of Surface Science and Engineering
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• v.49 no.6
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• pp.560-566
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• 2016

In this study, porcelain bonding strength and mechanical properties of sintered Ni-Cr-Ti alloy for dental prosthodontics have been researched experimentally. Mechanical and morphological characteristics of the alloys were examined by Vickers hardness test, tensile and bonding strength test, surface roughness test, field-emission scanning electron microscopy, energy dispersive X-ray spectroscopy, and X-ray diffraction. In the sintered Ni-13Cr-xTi alloys, morphology of sintered alloy showed porous matrix diffused with alloying elements of Cr and Ti, and showed dendritic structure after melting process. From the XRD results, the second phases of NiCr, $Ni_3Cr$, and $Ni_3Ti$ were formed in the case of sintered and melted Ni-13Cr-xTi alloys. The tensile strength and hardness of Ni-13Cr-xTi alloys increased, as Ti content increased. Surface roughness increased, as Ti content increased. The bonding strength between metal and porcelain of Ni-13Cr-5Ti alloy was higher than those of Ni-13Cr and Ni-13Cr-10Ti alloys

• Proceedings of the Korean Magnestics Society Conference
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• 1995.05a
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• pp.86-87
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• 1995

• Journal of the Korean Magnetics Society
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• v.3 no.3
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• pp.215-220
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• 1993

Microstructural dependence of magnetic property of RF/DC sputtered $Co_{69.0}Ni_{18.5}Cr_{12.5}/Cr$ double layer thin film was studied. Grain size was found to be decreased with substrate temperature in the range of $100-200^{\circ}C$ and Cr underlayer thickness(from $500\;{\AA}-2000\;{\AA}$). The peaks (200) and (1120) of X-ray diffraction patterns were evidently grown with the substrate temperature for the Cr underlayer and magnetic layer, respectively. The CoNiCr magnetic layer was found to be well epitaxialy grown on Cr underlayer, and subsequently the coercivity was enhanced.

• Korean Journal of Materials Research
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• v.8 no.9
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• pp.849-855
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• 1998

The purpose of this study was performed to compare to the characteristics (microstructure, phase change and hardness, erosion rate) of HVOF sprayed coatings with 20wt% NiCr claded and 7wt%NiCr mixed $\textrm{Cr}_{3}\textrm{C}_{2}$ powder. In the case of the 20wt% NiCr claded $\textrm{Cr}_{3}\textrm{C}_{2}$ powder, microstructural feature showed that the primary $\textrm{Cr}_{3}\textrm{C}_{2}$ was remained in the coating but was barely remained in the mixed $\textrm{Cr}_{3}\textrm{C}_{2}$ coating. As a results of XRD analysis, both 20wt%NiCr claded and 7wt% NiCr mixed $\textrm{Cr}_{3}\textrm{C}_{2}$ powder was decomposed during spraying but the degree of decomposition of the 20wt%NiCr claded was lower than 7wt%NiCr mixed $\textrm{Cr}_{3}\textrm{C}_{2}$ powder. After spraying the mixed powder for microhardness was higher than claded $\textrm{Cr}_{3}\textrm{C}_{2}$ powder and which was increased up to $\textrm{Hv}_{300}$= 1665 after heat treatment to $1000^{\circ}C$. however. 20wt%NiCr claded $\textrm{Cr}_{3}\textrm{C}_{2}$ became to decrease at $600^{\circ}C$ which was the maximum.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2009.11a
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• pp.421-425
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• 2009

A study has been performed to investigate the thermo-mechanical effects of thermal barrier coating on liquid rocket regenerative cooling chamber using finite element analysis. Two kinds of thermal barrier coatings were studied on the same loading condition: first, NiCrAlY-$ZrO_2$, coating which is currently applied to the developing combustion chamber and second, Ni-Cr coating which might be applied in the future. Analysis results showed that NiCrAlY-$ZrO_2$ coating has better decreasing effect of temperature than the Ni-Cr coating. As a results, temperature and deformation of the cooling channel in the NiCrAlY-$ZrO_2$ coating were also less than those of the Ni-Cr coating. The Ni-Cr coating has no effect on a structural stability of the outer jacket but the NiCrAlY-$ZrO_2$ coating reduced the effective stress of the outer jacket and enhanced the structural stability of the chamber.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.20 no.6
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• pp.520-526
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• 2007

In order to acquire fundamental informations to fabricate high precision thin film resistors, NiCr/NiCrSi alloy films were prepared using Ni and Cr targets. Effect of composition on the electrical properties of the NiCr/NiCrSi alloy film were then investigated. Considering the effect of Si doping on the electrical and material characteristics, the lower TCR (temperature coefficient of resistance) values could be achieved for samples with Ni/Cr ratio of $0.8{\sim}1.5$ (in a range of relative higher specific resistivity and Cr composition of $40\;wt%{\sim}55\;wt%$) and with Si doping. Consequently, the sample prepared using a DC power showed a good TCR of $-25\;ppm/^{\circ}C$, which implies that increase of specific resistivity and decrease of TCR would be achieved more efficiently not for Ni-Cr binary material but for Si doped Ni-Cr ternary material, and not using RF power but using DC power in the sputtering process.

• Journal of the Korean Magnetics Society
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• v.7 no.4
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• pp.205-211
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• 1997

The magnetic properties change which was induced by addition of small amount of Ni into Cr underlayer in CoCrTa/ CrNi thin film deposited by electron beam evaporator was investigated. The additional Ni element was found to be beneficial for incease in the coercivity of the thin film deposited at the room temperature. The origin of coercivity increase was elucidated by crystal orientation and microstructure investigation using XRD and AFM respectively. It was found that the grain size were increased by Ni addition. The coercivity of the film with CrNi underlayer is lower than that of film with Cr underlayer when prepared with higher substrate temperature. This result may be originated with the increase in grain size. When film was deposited at 280 $^{\circ}C$ substrate temperature, Cr segregation in grain boundary is found to be the other factor for determining coercivity value.