• 한국표면공학회지
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• 제21권2호
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• pp.39-46
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• 1988

Corrosion behavior of 5-26wt% Ni-Zn electrodeposited alloys was investigated by means of dipping electrochmical polarization measurement and galvanic coupling test. The weight loss and anodic polarization curve of coatings were measured by means of dipping and polarization measurement respectively. The galvanic protection effect of alloy coatings was measured by galvanic coupling test and the surface morpholgy of coatings was observed after corrosion testing. Our findings support thous of previous investigations showing that ${\gamma}$single phase coatings, while galvanic pprotection effect of dual phase coatings improved in comparison with ${\gamma}$single phase coating. The formation of colony in coating of ${\gamma}$and η+${\gamma}$ dual phsae caused the localized corrsion and increased the corrosion rate of the Ni-Zn coating.

• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2011년도 춘계학술대회 및 Fine pattern PCB 표면 처리 기술 워크샵
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• pp.46-46
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• 2011

각종산업의 건축자재, 전기기기 등의 분야에서 내식성 향상용 표면처리 도금재로 가장 많이 사용되고 있는 아연과 실용금속 중 가장 가벼우면서 비강도 및 치수 안정성이 뛰어난 Mg을 사용하여 Zn-Mg의 합금 박막을 제작하였다. 여기서는 Zn, Mg 단일 박막의 밀착성과 내식성의 한계점을 극복하기 위해서 모재와 코팅층 사이에 Al을 삽입하여 (Zn-Mg)/Al 합금 박막을 형성시켰다. 또한 박막의 증착과정 중 이들 막의 제어는 바이아스 전압을 일정하게 하고 진공도를 변수로 하였고, 진공도에 따라 달라지는 쳄버내의 가스 입자가 흡착 인히비터로 작용해서 박막의 몰포로지와 결정배향성의 구조에 중요한 영향을 준다는 것을 확인하였다. 그리고 이들 박막의 내식성과 밀착성에 미치는 몰포로지나 결정배향성과의 상관관계를 규명하여 최적의 코팅 프로세스를 결정하므로써 중간층 유무별 Zn계 합금박막의 기초적인 제작설계 지침을 제공하였다.

• 한국표면공학회지
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• 제30권2호
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• pp.128-135
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• 1997

The effect of the polyethyledglycol(PEG) on the surface morphology and crystal orientation of electrodeposited zinc from a chloride (1.5M Zinc+7.0M chloriode) have been studied by means of electrochemical methodes, scanning electron microscopy, surface appearance measurement and X-ray diffraction patterns. The resistance of electrodeposit increased, whereas the evolution of hydrogen decreased with incrasing of molecular weight of the PEG. Large grains of electrodeposit were obtained from bath in the absence of organid additive. When the PEG was added, fine grained crystals were observed and the surface roughness was relatively small, but surface appearance deteriorated. The preferred orientation with a(101) plane parallel to the surface was obtained from the PEG addited bath.

• 한국분무공학회지
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• 제6권1호
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• pp.44-51
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• 2001

The distributions of the SMD and behavior of 2% $NH_4H_2PO_4$ spray discharged from a fan-spray twin fluid type nozzle are measured and observed. The spray characteristics, according to the variation in the applied voltages, are demonstrated using the PMAS (particle Motion Analysis System) and the CCD camera, respectively. The preliminary experiments are executed to select an optimum condition for solidifying a galvanized coating layer in the uncharged condition before carrying out the main experiments. The liquid and air pressure of $0.07kgf/cm^2\;and\;0.15kgf/cm^2$ can be considered the optimum conditions to use in the main experiment. As the applied voltage increases, the frequent range of relatively large droplets diminishes. Thus, the distributions of drop diameter in the charged spray are more uniform than these in the uncharged condition. This is explained by recognizing that repulsive forces among droplets with the charges of the same sign cause them to be uniform.

• 한국표면공학회지
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• 제43권2호
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• pp.51-56
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• 2010

The zinc electroplating with respect to the chloride concentration was investigated by X-ray diffraction(XRD), scanning electron microscope (SEM), and cathodic polarization measurement. The cathodic overpotential during electroplating was first decreased and then increased with increase of chloride concentration in electrolyte. The decreased cathodic overpotential leads to preferred orientation of (002) plane, high current efficiency and satisfactory zinc deposits. The increased cathodic overpotential causes random orientation, low current efficiency and edge burning. The cathodic overpotential was affected by chloride concentration in electrolyte, not by the kind of chloride, such as NaCl and KCl. An optimized chloride concentration was 3 M for zinc electroplating. Also, it is considered that NaCl can be a alternation for KCl as a main salt of zinc electroplating bath.

• Corrosion Science and Technology
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• 제22권5호
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• pp.341-350
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• 2023

In the present study, effects of a thin Zn-flash coating on hydrogen evolution, infusion, and embrittlement of advanced high strength steel during electro-galvanizing were examined. The electrochemical permeation technique in conjunction with impedance spectroscopy was employed under applied cathodic polarization. Moreover, a slow-strain rate test was conducted to evaluate loss of elongation (i.e., indicative of hydrogen embrittlement (HE)) and examine fracture surfaces. Results showed that the presence of a thin Zn-flash coating, even when it was not distributed uniformly, reduced hydrogen evolution rate and substantially impeded infusion of hydrogen into the steel substrate. This was primarily due to a hydrogen overvoltage on Zn coating and trapping of hydrogen at the interface of Zn coating/flash coating/steel substrate. Consequently, the sample with flash coating had a smaller HE index than the sample without flash coating. These results suggest that a thin Zn-flash coating could be an effective technical strategy for mitigating HE in advanced high-strength steels.

• 한국수소및신에너지학회논문집
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• 제31권1호
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• pp.23-32
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• 2020

The intermittent characteristics of renewable energy complicates the process of balancing supply with demand. Electrolysis technology can provide flexibility to grid management by converting electricity to hydrogen. Alkaline electrolysis has been recognized as established technology and utilized in industry for over 100 years. However, high overpotential of oxygen evolution reaction in alkaline water electrolysis reduces the overall efficiency and therefore requires the development of anode catalyst. In this study, Raney Ni-Zn-Fe electrode was prepared by electroplating and the electrode characteristics was studied by varying electroplating parameters like electrodeposition time, current density and substrate. The prepared Raney Ni-Zn-Fe electrode was electrochemically evaluated using linear sweep voltammetry. Physical and chemical analysis were conducted by scanning electron microscope, energy dispersive spectrometer, and X-ray diffraction. The plating time did not changed the morphology and composition of the electrode surface and showed a little effect on overpotential reduction. As the plating current density increased, Fe content on the surface increased and cauliflower-like structure appeared on the electrode surface. In particular, the overpotential of the electrode, which was prepared at the plating current density of 320 mA/㎠, has showed the lowest value of 268 mV at 50 mA/㎠. There was no distinguishable overpotential difference between the type of substrate for the electrodes prepared at 80 mA/㎠.

• 한국표면공학회지
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• 제28권5호
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• pp.320-328
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• 1995

The electroplated steel sheets were heated during the short periods(10~60 seconds) at high temperature ($360^{\circ}C$～$500^{\circ}C$) in order to investigate thermal diffusion behaviors. When the steel sheets were heated for 10 seconds, all the coated layers were alloyed at $420^{\circ}C$ but at temperature lower than $400^{\circ}C$ the $\eta$ phase partially remained on the coated surface. At higher temperature, the longer the time for heat treatment the iron contents were increased in coated layer but the glossiness and whiteness of the coated surface were decreased. While the alloying phases of $\eta$, $\zeta$, $\delta_1$ and $\Gamma$ were appeared in the coated layer at the heat treatment temperature of $360^{\circ}C$, the phase was disappeared at $420^{\circ}C$ but the rests grew in size at the temperature of $440^{\circ}C$. When the heat treatment temperature and heating time were increased, the thickness of $\Gamma$ phase was rapidly increased to 0.8 $\mu\textrm{m}$. The optimum conditions for the heat treatment to prevent powdering of coated layer were obtained to heat it for 30 seconds at $400^{\circ}C$ and 10 seconds at $440^{\circ}C$, and the iron content in coated layer was suited to be 10 percents.

• 한국재료학회지
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• 제12권2호
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• pp.146-152
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• 2002

Effect of polyaniline and additives on surface appearance of Zn electrodeposition was investigated by SEM and XRD analyzing. We carried out the experiment from sulfate Zinc bath containing sulfonated polyaniline, gelatin and thiourea by EG(Electrogalvanizing) simulator. Addition of polyaniline and gelatin in bath, crystal size and shape of hexagonal plane of Zn crystal reduced. Mixing of thiourea, however, brittle deposits were observed because of the difference between vertical growth and parallel growth. (1011) peak appeared with polyaniline and gelatin in XRD analysis. In case of mixing of polyaniline, gelatin and thiourea, (1011) peak appeared and intensity of Zn basal plane decreased. These results suggested that overpotential increased with addition of polyaniline and additives In bath.

• 한국마린엔지니어링학회:학술대회논문집
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• 한국마린엔지니어링학회 2006년도 전기학술대회논문집
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• pp.271-272
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• 2006

Zinc confers high corrosion resistance by acting as a sacrificial anode, and a zinc coating improves the appearance of steel. Chromate conversion coating (CCC) films are still one of the most efficient surface treatments for steel. Although such films can self-repair via the dissolution of Cr(VI), dissolved Cr(VI) have adverse effects on humans, and the environment. Therefore, we examined the corrosion protection property and morphology of colloidal silica conversion films as an alternative to CCC films. The corrosion behavior was investigated in 3% NaCl solution using electrochemical techniques, including electrochemical impedance spectroscopy, open circuit potential, and the salt spray test(SST). Corrosion was implied by the appearance of red rust on the specimen surface. In corrosion resistance at 3% NaCl solution, red rust appeared at 15-20, 55-70, and 83-98 days on Zn-electroplated steel, colloidal silica conversion-coated specimens, and CCC-coated specimens, respectively. In the salt spray test, the colloidal silica film provided better corrosion protection than CCC films, i.e., red rust appeared at 96 hours on the Zn-electroplated steel sheet, at 432 hours with the CCC films, and at 888 hours with silica conversion coating.