• Corrosion Science and Technology
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• v.3 no.4
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• pp.131-139
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• 2004

Effects of PbO on the repassivation kinetics and characteristics of passive film of Alloy 690 were examined to elucidate the influences of PbO on the SCC resistance of that alloy. The repassivation kinetics of the alloy was analyzed in terms of the current density flowing from the scratch, i(t), as a function of the charge density that has flowed from the scratch, q(t). Repassivation on the scratched surface of the alloy occurred in two kinetically different processes; passive film initially nucleated and grew according to the place exchange model in which log i(t) is linearly proportional to q(t), and then grew according to the high field ion conduction model in which log i(t) is linearly proportional to 1/q(t) with a slope of cBV. The cBV is found to be a parameter representing repassivation rate and hence SCC susceptibility of the alloy. The lower the value of cBV, the faster the repassivation rate and the higher the SCC resistance of an alloy. Addition of PbO to pH 4 and 10 solutions increased the value of cBV of alloy 690, reflecting slower repassivation rate than without PbO. The change in the value of cBV was grater in pH 10 than in pH 4. The increase in SCC susceptibility of alloy 690 with the addition of PbO to solution was presumably due to the Cr-depletion in the outer parts of passive film of the alloy with an incorporation of Pb compounds in the film, which was revealed by Mott-Schottky, AES and XPS analyses.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2017.05a
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• pp.95.1-95.1
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• 2017

In this study, it has been tried to make the single Mo-Cu alloying targets with the Cu showing the best surface hardness that was determined by investigation on the coatings with the double target process. The single alloying targets were prepared by powder metallurgy methods such as mechanical alloying and spark plasma sintering. The nanocomposite coatings were prepared by reactive magnetron sputtering process with the single alloying targets in $Ar+N_2$ atmosphere. The microstructure changes of the Mo-Cu-N coatings with diverse Cu contents were investigated by using XRD, SEM and EDS. The mechanical properties of the coatings were evaluated by using nano-indentor, scratch test, and ball on disc methods. Especially, the coated samples were tested by using various lubricating oil to compare the property of anti wear-resistance. In this study, the nano-composite MoN-Cu coatings prepared using an alloying target was eventually compared with the coatings from the multiple targets.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.08a
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• pp.177-179
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• 2011

The purpose of this study is to enhance an adhesion between substrate and Diamond-like Carbon (DLC) film. DLC has many outstanding properties such as low friction, high wear resistance and corrosion resistance. However, it is difficult to achieve enough adhesion because of weak bonding between DLC film and the substrate. For improvement adhesion, a layer between DLC film and the substrate was prepared by dual post plasma. DLC film was deposited on nitrided layer by linear ion source. The composed compound layer between substrate and DLC film was investigated by Glow Discharge Spectrometer (GDS) and Scanning Electron Microscope (SEM). The synthesized bonding structure of DLC film was analyzed using a micro raman spectrometer. Mechanical properties were measured by nano-indentation. In order to clarify the mechanism for improvement in adhesive strength, it was observed by scratch test.

• Journal of the Korean Ceramic Society
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• v.46 no.5
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• pp.497-504
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• 2009

DLC is considered as the candidate material for application of moving parts in automotive components relatively in high pressure and temperature operating conditions for its high hardness with self lubrication and chemical inertness. Different deposition method such as arc plating, ion gun plating and PECVD were used for comparing mechanical and tribological properties of each DLCs deposited on stainless steel with 1 um thick respectively. Among these 3 types of DLCs, the arc plated DLC film showed highest value for wear resistance in dry condition. From the results of analysis for physical properties of DLC films, it seems that the adhesion force and crack initiation modes were more important factors than intrinsic mechanical properties such as hardness, elastic modulus and/or roughness to the wear resistance of DLC films. Raman spectroscopy was used for understanding chemical bonding natures of each type of DLC films. Typical D and G peaks were identified based on the deposition method. Hardness of the coating layers were identified by nanoindentation method and the adhesions were checked by scratch method.

• Journal of the Korean institute of surface engineering
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• v.49 no.2
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• pp.141-146
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• 2016

In this study, electrophoretic paint (E-paint) was deposited on the knife-abraded surface of AZ31 magnesium alloy (AZ31), and its adhesion and corrosion resistance were examined by tape peel-test and salt spray test, respectively. E-paint started to deposit on AZ31 Mg alloy after an inductance time and pores were found in the E-paint layer which is ascribed to hydrogen bubbles generated on the surface during the painting process. The pores disappeared after curing for 15 min at $160^{\circ}C$. The E-paint on AZ31 exhibited good adhesion after immersion in deionized water for 500 h at $40^{\circ}C$. The E-paint sample without scratch showed no corrosion after 1500 h of salt spray test. However, on the scratched sample, blisters were visible adjacent to the scratched sites after 500 h of salt spray test.

• Progress in Superconductivity and Cryogenics
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• v.24 no.4
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• pp.40-45
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• 2022

The electrical/thermal stabilities and magnetic field controllability of a no-insulation (NI) high-temperature superconducting magnet are characterized by contact resistance between turn-to-turn layers, and the contact resistance characteristics are determined by properties of conductor surface and winding tension. In order to accurately predict the electromagnetic characteristics of the NI coil in a design stage, it is necessary to control the contact resistance characteristics within the design target parameters. In this paper, the contact resistance and critical current characteristics of a rare-earth barium copper oxide (REBCO) conductor were measured to analyze the effects of surface treatment conditions (roughness and oxidation level) of the copper stabilizer layer in REBCO conductor. The test samples with different surface roughness and oxidation levels were fabricated and conductor surface analysis was performed using scanning electron microscope, alpha step surface profiler and energy dispersive X-ray spectroscopy. Moreover, the contact resistance and critical current characteristics of the samples were measured using the four-terminal method in a liquid nitrogen impregnated cooling environment. Compared with as-received REBCO conductor sample, the contact resistance values of the REBCO conductors, which were post-treated by the scratch and oxidation of the surface of the copper stabilizer layer, tended to increase, and the critical current values were decreased under certain roughness and oxidation conditions.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.19 no.9
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• pp.825-831
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• 2006

As an increase of chip complexity and level of chip integration, chip input/output (I/O) pad pitches are also drastically reduced. With arrival of high complexity SoC (System on Chip) and SiP (System in Package) products, conventional horizontal type probe card showed its limitation on probing density for wafer level test. To enhance probing density, we proposed new vertical type probe card that has the $70{\mu}m$ probe needle with tungsten wire in $80{\mu}m$ micro-drilled hole in ceramic board. To minimize alignment error, micro-drilling conditions are optimized and epoxy-hardening conditions are also optimized to minimize planarity changes. To apply wafer level test for target devices (T5365 256M SDRAM), designed probe card was characterized by probe needle tension for test, contact resistance measurement, leakage current measurement and the planarity test. Compare to conventional probe card with minimum pitch of $50{\sim}125{\mu}m\;and\;2\;{\Omega}$ of average contact resistance, designed probe card showed only $22{\mu}$ of minimum pitch and $1.5{\Omega}$ of average contact resistance. And also, with the nature of vertical probing style, it showed comparably small contact scratch and it can be applied to bumping type chip test.

• Corrosion Science and Technology
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• v.9 no.6
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• pp.289-293
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• 2010

To investigate the corrosion behavior of tools steel surface in various coating film, the surface of hard coated Ti-Zr-N film on the tool steel by using magnetron-sputtering methods was researched using various experimental methods. STD 61 steels were manufactured by using vacuum furnace and solutionized for 1hr at $1050^{\circ}C$. Steel surface was coated with Ti-Zr-N film at $150^{\circ}C$ and 100W for 1h by using DC-sputtering equipment. Surface characteristics of Ti-Zr-N film coated specimens were investigated by OM, XRD, FE-SEM and nano-scratch tester. And corrosion behaviors of the coated specimen were investigated by polarization test and electrochemical impedance spectroscopy(EG&G Co, PARSTAT 2273. USA). It was found that Ti-Zr-N film coated sample had a thick coated layer and showed a good wear resistance and corrosion resistance of surface compared with ZrN and TiN coated sample. The corrosion resistance and mechanical property of Ti-Zr-N film coated STD 61 alloy increased as sputtering time increased.

• Journal of the Korean institute of surface engineering
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• v.51 no.6
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• pp.405-414
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• 2018

The present study investigated the adhesion and corrosion resistance of subsequent electrophoretic paint (E-paint) on "electroless" paint coated AZ31 Mg alloy, which was formed by immersion of AZ31 Mg alloy in E-painting solution. It was found that with increasing immersion time of AZ31 in E-painting solution, the amount of paint deposited by electroless process increased but it decreased the electrochemical equivalent of E-painting process and the adhesion of the subsequent E-paint layer. The E-paint on electroless paint coated AZ31 contained pores with the highest pore density and the largest pore size was obtained on the samples with electroless times of 2 and 5 minutes, respectively. Results of the salt-spray test showed an accelerated growth of blisters over the entire surface of the sample immersed for less than 5 minutes whereas blisters were observed only in the vicinity of the scratch in case of samples treated for 15 and 30 minutes. The E-paint on AZ31 with shorter electroless immersion time in E-painting solution was found to have good adhesion and better corrosion resistance.

• Journal of Korean Public Health Nursing
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• v.24 no.1
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• pp.39-48
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• 2010

Purpose: To examine the effects of a 36-week resistance training program on body composition, fitness and blood lipid profiles in the obese elderly. Method: fourteen subjects were assigned into the resistance training group. The 12-16 exercise sessions were performed for 60min with 15-25 repetitions twice per week for 36 weeks. Data were analyzed by paired t-test with SPSS version 12.0 for Windows. Results: Significant changes were evident in weight (t=5.983, p<.001), body mass index (t=5.922, p<.001), % body fat (t=3.480, p=.004), and fat free mass (t=-2.592, p=.022). Concerning exercises, no significance was noted for back scratch (t=-1.814, p=.093), but were for 2-min step (t=-3.075, p=.009), arm curl (t=-2.223, p=.045), chair stand (t=-3.671, p=.003), chair sit and reach (t=-2.508, p=.026), and 8-ft up and go (t=5.545, p<.001). No significant changes were evident in total cholesterol (t=1.189, p=.279), and total glucose (t=0.689, p=.517), while the change in high-density lipoprotein was significant (t=3.535, p=.012). Conclusion: The 36-week resistance training program enhanced body composition and physical fitness, but not blood lipid profiles in obese elderly subjects.