• Membrane and Water Treatment
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• v.5 no.1
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• pp.41-56
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• 2014

A series of microporous PVDF membranes were prepared by isothermal immersionprecipitation of PVDF/TEP casting dopes in both soft and harsh coagulation baths. Morphologies of the membranes' top surfaces were found to depend strongly on the bath strength, which could be controlled by the TEP content in the bath. By changing the bath gradually from pure water to 70% TEP, the top surface evolved from a dense skin-like (asymmetric) to a totally open porous morphology (symmetric). The latter structure could similarly be obtained by precipitation of the same dope in an alcoholic bath, e.g., 1-butanol. Membrane distillation processes to desalt sodium chloride aqueous solutions were conducted using various prepared membranes and two commercial microporous membranes, PTFE (Toyo, Japan, code: J020A330R) and PVDF (GE, USA, code: YMJWSP3001). The permeation fluxes were compared and correlated with the morphologies of the tested membranes.

• Journal of the Korean institute of surface engineering
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• v.36 no.5
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• pp.379-385
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• 2003

The surface morphology, the glossiness and the hardness of Zn-Cr and Zn-Cr-X(X:Co, Mn) alloy electrodeposits were investigated by using chloride bath with EDTA additive and flow cell system. The surface morphology of Zn-Cr alloy and Zn-Cr-Mn alloy changed from fine needle shape crystalline structure to colony structure of fine granular crystallites with increasing current density in the range of 20-100 $A/dm^2$. The surface morphology of Zn-Cr-Co alloy deposited from low Co concentration bath(2.5-10 g/$\ell$) was similar to that of Zn-Cr alloy, while that of Zn-Cr-Co alloy deposited from high cobalt concentration bath was fine granular crystalline structure in the same range of current density. The glossiness of Zn-Cr and Zn-Cr-Mn alloy increased noticeably with increasing current density, while that of Zn-Cr-Mn alloy decreased with increasing Mn concentration of bath in high current density region. The glossiness of Zn-Cr-Co alloy deposited from low Co concentration bath increased with current density while that of the alloy from high Co concentration bath decreased with increasing current density. The hardness of Zn-Cr and Zn-Cr-X alloy increased noticeably with current density.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 1998.05a
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• pp.86-86
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• 1998

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2003.10a
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• pp.138-138
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• 2003

• Journal of the Korea Convergence Society
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• v.9 no.10
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• pp.271-276
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• 2018

In the industry, Zn galvanizing on the steel using the principle of sacrificial anode is used. The steel have some problem, specially corrosion problem. To solve corrosion problem, Zn-Mn alloy plating has been studied as one of the measures to increase the corrosion resistance rather than pure zinc plating. It is possible to be applied to automotive parts requiring high corrosion resistance even though the plating cost is high. In this study, Zn-Mn alloys were electrodeposited from an acidic chloride bath. The influence of the electrolytic conditions on the composition of the alloy plating in the chloride bath was investigated. As the current density of the cathode increases, Zn content of electrodeposit decrease and Mn content of electrodeposit increase. As the temperature of the electrolyte increases, Zn content of electrodeposit decrease and Mn content of electrodeposit increase. The results are explained by the cathode overvoltage curve of Mn and Zn.

• Journal of the Korean Magnetics Society
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• v.23 no.1
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• pp.12-17
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• 2013

Nanocrystalline nickel (Ni) tick films were synthesized by direct current electrodeposition at current density from 1 to $30mA/cm^2$ and pH = 4. The basic composition of the bath, which was prepared by dissolving Ni metal particles in HCl, was 0.2M Ni ions. The effects of the current density on the average grain size of Ni deposits were investigated by XRD and SEM techniques. The results showed that the surface roughness was decreased as the saccharin addition was increased up to 2 g/l. The experimental results showed that the increase in the current density had a considerable effect on the average grain size of the Ni deposits. The perpendicular magnetization was raised as the thickness of coating layer was increased.

• Journal of the Korea Convergence Society
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• v.9 no.11
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• pp.285-290
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• 2018

The steel has been used in modern industry, car maker and electric appliance. The steel have some problem, specially corrosion problem. To solve corrosion problem, Zn electrodeposit on steel have been adapted. Recently, The modern industry asks to increase corrosion resistance. Naturally, Increasing corrosion resistance increases the thickness of Zn electrodeposit. But increasing thickness of Zn electrodeposit has some problems. In making part, There are some crack. This crack cause to decrease corrosion resistance. To solve this problem, it is interested in Zn Based alloy electrodeposit such as Zn-Cr. Here, the influence of the electrolytic conditions on the composition of the alloy plating in the chloride bath was investigated. The results are explained by the cathode overvoltage curve of Cr and Zn. As the current density of the cathode increases, Zn content of electrodeposit decrease and Cr content of electrodeposit increase. As the temperature of the electrolyte increases, Zn content of electrodeposit decrease and Cr content of electrodeposit increase.

• Journal of the Korean Applied Science and Technology
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• v.10 no.2
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• pp.29-33
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• 1993

n-Octyldimethylbenzylammonium chloride, dodecyldimethylbenzylammonium chloride, and octadecyldimethylbenzylammonium chloride were synthesized to be used as the accelerating weight loss agent. These synthesized compounds were used for the weight loss treatment of PET textile with sodium hydroxide. From the treatments, it was found that the lower carbon number of high alkyl group existed in quaternary ammonium salts, the better effect of weight loss was acquired. The proper concentration of accelerating weight loss agent was $8{\sim}10g/l$, the proper treatment time was $60{\sim}90$ minutes, the proper treating bath ratio was 1 : 50. It is proved that n-octyldimethylbenzylammonium chloride and dodecyldimethylbenzylammonium chloride are good accelerating weight loss agent.

• Journal of Korean Society for Atmospheric Environment
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• v.2 no.3
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• pp.27-33
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• 1986

Atmospheric particulate matter (A. P. M.) was collected and size-fractionated by an Andersen high-volume air sampler over 15 month period from Jan. 1985 to Feb. 1986 in Seoul. The concentration of chloride, nitrate and sulfate were extracted in an ultrasonic bath and were analyzed by ion chromatography. The annual arithmetical mean of A. P. M. was 128.54 $\mug/m^3$. The concentration of anions were 2.88 $\mug/m^3$ for chloride, 3.86$\mug/m^3$ for nitrate, and 25.44$\mug/m^3$ for sulfate. The content of A. P. M. was lowest in the particle size range 1.1 $\sim 3.3\mum$ and increased as the particle size increased or decreased. And the anions exhibited a seasonal variation in the isize distribution. The contents of anions were higher in winter than summer. Ther ratio of fine particles to the total particles defined by F/T for chloride, nitrate and sulfate. The F\ulcornerT of these anion generally decrease with increasing air temperature. This tendency was prevalent in the chloride and nitrate.

• Journal of the Korean institute of surface engineering
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• v.43 no.2
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• pp.105-110
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• 2010

Electroless nickel plating on porous carbon substrate for the application of MCFC electrodes was investigated. Acidic and alkaline bath were used for the electroless nickel plating. The pore sizes of carbon substrates were 16-20 ${\mu}m$ and over 20 ${\mu}m$. The carbon surface was changed from hydrophobic to hydrophilic after immersing the substrate in an ammonia solution for 40 min at $60^{\circ}C$. The contact angle of water was decreased from $85^{\circ}C$ to less than $20^{\circ}$ after ammonia pretreatment. The deposition rate in the alkaline bath was higher than that in the acidic bath. The deposition rate was increased with increasing pH in both acidic and alkaline bath. The content of phosphorous in nickel deposit was decreased with increasing pH in both acidic and alkaline bath. The contents of phosphorous is low in alkaline bath. The minimum concentration of $PdCl_2$ for the electroless nickel plating was 10 ppm in alkaline bath and 5 ppm in acidic bath. The thickness of nickel was not affected by the concentration of $PdCl_2$.