• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2004.10a
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• pp.276-279
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• 2004

The factors affecting Ni-Co alloy electroforming were investigated to determine the optimum bath composition and electroplating parameters, like pH, temperature, and current density, suitable for high speed fabrication of a micro mold with longer lifetime. To obtain alloy deposits having uniform thickness and composition, electroplating parameters were finely tuned with home-made electroforming apparatus. Ni-Co alloy deposits had linearly increased Co with $Co^{2+}$ ion concentration in electroplating bath, and showing $412H_v$ of Victors hardness at $23wt\%$ of Co content. For Ni-Co alloy, sulfonate and diol related organic additives were very effective to alleviate its residual stress and surface roughness. The maximum deposition rate was $106{\mu}m/hr$ at 10ASD and the tensile strength of alloy deposit was 2 times larger than that of Ni only case.

• Journal of Technologic Dentistry
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• v.35 no.1
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• pp.1-17
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• 2013

Purpose: This study was to assess the extents of the release of metals from the non-precious alloys used for dental casting by measuring the differences in the extents of the release of metals by types of alloys, pH level and elapsed time. Methods: Uniform-sized specimens(10 each) were prepared according to the Medical Device Standard of the Korea Food and Drug Administration(2010) and International Standard Organization(ISO22674, 2006), using four types of alloys(one type of Ni-Cr and one type of Co-Cr used for fixed prosthesis, and one type of Ni-Cr and one type of Co-Cr used for removable prosthesis). A total of 12 metal-release tests were performed at one-day, three-day, and two-week intervals, for up to 20 weeks. The metal ions were quantified using an Inductively Coupled Plasma-Atomic Emission Spectrometer. Results: The results showed that the extent of corrosion was higher in the ascending order of Jdium-$100^{(R)}$, Bellabond-$Plus^{(R)}$, Starloy-$C^{(R)}$, and Biosil-$F^{(R)}$. The lower the pH and the longer the elapsed time were, the greater the increase in metal corrosion. At pH 2.4, the release of Ni from Jdium-$100^{(R)}$, a Ni-Cr alloy, was up to 15 times greater than the release of Co from the Co-Cr alloy from two weeks over time, indicating that the Ni-Cr alloy is more susceptible to corrosion than the Co-Cr alloy. Conclusion: It is recommended that Co-Cr alloy, which is highly resistant to corrosion, be used for making dental prosthesis with a non-precious alloy for dental casting, and that non-precious alloy prosthesis be designed in such a way as to minimize the area of its oral exposure. For patients with non-precious alloy prostheses, a test of the presence or absence of periodontal tissue inflammation or allergic reaction around the prosthesis should be performed via regular examination, and education on the good management of the prosthesis is needed.

• Journal of Technologic Dentistry
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• v.34 no.4
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• pp.353-359
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• 2012

Purpose: The aim of this study measured and compared the marginal and internal fit of metal cores with two base metal alloy (Ni-Cr alloy(non-beryllium), Co-Cr alloy). Methods: Maxillary right first molar abutment fabricated by titanium was prepared for this study. Impressions(10ea) were made from titanium model, and study models were poured with improved dental stone. Wax cores of twenty were prepared for burn-out and casting. Ten wax cores cast Ni-Cr alloy(non-Be), and finally ten cast Co-Cr alloy. Marginal and internal fit of cores was evaluated using silicone replica technique and digital microscope(x160). The data were statistically analyzed with the independent samples t-test (${\alpha}$ <.05). Results: Mean(standard deviation, SD) marginal and internal fit total size of Ni-Cr alloy(non-Be) group was $73.3(14.4){\mu}m$ and of Co-Cr alloy group $65.6(17.4){\mu}m$. The marginal and internal fit total size of Ni-Cr alloy group(non-Be) was statistically significantly greater than that of Co-Cr alloy group (P=.004). Conclusion: Co-Cr alloy cores in this study had a better marginal fit than Ni-Cr alloy(non-Be) cores.

• Journal of Technologic Dentistry
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• v.33 no.3
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• pp.185-192
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• 2011

Purpose: This study was to evaluate the shear bond strength of the ceramic fused to Ni-Cr alloy(Bellabond plus) and Co-Cr alloy(Wirobond C) by heat treatment. Methods: Metal specimens were divided into 5 groups for each alloy according to heat treatment conditions prior to porcelain application. Fifteen specimens from each group were subjected to a shear load a universal testing machine using a 0.1mm/min cross-head speed and one specimen from each group was observed with EDX line profile. Results: The diffusion of metal oxide observed far in the specimen heat treated than no heat treated in the opaque layer. The shear bond strength measured highest to BP3(50.50MPa), WC2(50.49MPa) groups and measured lowest from BP1(35.1MPaa), WC1(39.66MPa) groups which were not treated with heat, and there was a significant difference (p<0.05). Conclusion: The shear bond strength of Ni-Cr alloy(Bellabond plus) and Co-Cr alloy(Wirobond C) measured similar 5 groups all.

• Journal of the Microelectronics and Packaging Society
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• v.24 no.3
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• pp.77-81
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• 2017

Pulse electroplating of Ni-P alloy was studied to fulfill the material requirement to the advanced vertical probe tip in wafer probe card. The major concerns are for the electrical conductivity and yield strength. Plating parameters such as current density, duty cycle and solution components were examined to obtain the nanocrystal structure and proper percentage of phosphorus, leading to how to control the nanocrystal grain growth and precipitation of $Ni_3P$ after heat treatment. Among the parameters, the amount of phosphorus acid was the main factor affecting on the grain size and sheet resistance, and the amount of 0.1 gram was appropriate. Since hardness in Ni-P alloy is increased by as-plated nanocrystal structure plus precipitation of $Ni_3P$, the concentration of P less than 15 at% was better choice for the grain coarsening without minus in hardness value. The following heat treatment made grain growth and dispersion of precipitates adjustable to meet the target limit of resistance of $100m{\Omega}$ and hardness number of over 1000Hv. The Ni-P alloy will be a candidate for the substitute of the conventional probe tip material.

• Journal of the Korean Magnetics Society
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• v.5 no.2
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• pp.134-139
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• 1995

We produced $(Co_{93}Cr_{7})-P-Ni$ thin films for longitudinal magnetic recording media using OC magnetron sputtering system The variation of magnetic properties of $(Co_{93}Cr_{7})-P-Ni$ pseudo-ternary system with the composition was examined. We obtained the coercivity up to 1500 Oe. The coercivity iocrease could be ascribed to in-plane anisotropy enhaocement, grain size decrease, magnetic decoupling between particles. TEM micrographs showed that the grains were well-decoupled by the addition of phosphorous.

• Journal of the Korean institute of surface engineering
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• v.24 no.2
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• pp.96-102
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• 1991

Co-Ni-P alloys were electrodeposited from NH4Cl-sulfate-hypophosphite baths under various plating conditions. Their effective anisotropic magnetic field which is one of the important properties for magnetic recording materials were investigated as the function of alloy compositions and c-axis orientation. The preferred orientation and the contents of Ni and P depend on the pH of solutions and also on the current density. It was found that the alloy films deposited from the solutions of pH4 at high current density had c-axis orientation parallel to the growth direction and the effective anisotropic fields sufficient for perpendicular magnetic recording application.

• Transactions of the Korean hydrogen and new energy society
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• v.10 no.3
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• pp.185-189
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• 1999

Effects of alloy modification with the $Zr_{0.6}Ti_{0.4}V_{0.4}Ni_{1.2}Mn_{0.4}$ alloy for an electrode use have been investigated. For the alloy composition, a part of Mn was substituted by Co, Cr and Fe. The experimental results showed that Co accelerated activation of alloy, and Fe and Cr improved the discharge capacity. These results agree with P-C-T curves of each alloy. But substituting Fe for Mn showed the decrease of the discharge capacity when discharged at high rate (60mA, about 1C rate). Considering both the discharge capacity and the high rate discharge property, $Zr_{0.6}Ti_{0.4}V_{0.4}Ni_{1.2}Mn_{0.3}Cr_{0.1}$ alloy was found to be the best alloy among the alloys subjected to the test.

• Journal of Power System Engineering
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• v.18 no.6
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• pp.40-44
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• 2014

The purpose of this paper is to investigate polarization characteristics of WC-based alloy coatings in alkaline solution. The coatings were fabricated with WC-CrC-Ni, WC-Co-Cr and WC-Co composite powders by HVOF process. Corrosion tests of coatings and substrate were carried out using potentiostat/galvanostat at solution with pH 8 and pH 13. Corrosion potential(Ecorr) and corrosion current density(Icorr) could be studied from polarization curve, and corrosion behavior was analyzed by SEM and EDS. WC-Co-Cr coating and WC-CrC-Ni coating showed more favorable anti-corrosion characteristics than WC-Co coating and substrate at solution with pH 8 and pH 13.

• Journal of Power System Engineering
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• v.18 no.4
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• pp.72-77
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• 2014

The aim of this study to investigate polarization characteristics of WC-based alloy coatings fabricated by high velocity oxygen fuel(HVOF) process. The coatings were fabricated by HVOF process with WC-CrC-Ni, WC-Co-Cr, WC-Co composite powders. Corrosion tests were carried out using potentiostat/galvanostat at solution with pH 2 and pH 6. Corrosion potential(Ecorr) and corrosion current density(Icorr) could be analyzed from polarization curve. WC-Co-Cr coating showed more incorrodible characteristics than other coatings at solution pH 2. WC-CrC-Ni coating was more favorable anti-corrosion characteristics than other coatings at solution with pH 6.