• Proceedings of the Membrane Society of Korea Conference
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• 1994.10a
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• pp.8-11
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• 1994

Disposal of hazardous ions in the aqueous streams is a significant industrial waste problem.. Waste streams from electronics, electroplating, and photographic industries contain metal ions such as copper, nickel, zinc, chromium(IV), cadmium, aluminum, silver, and gold, amongst others in various aqueous solutions such as sulfates, chlorides, fluorocarbons, and cyanides. Typical plating solutions having similar compositions are listed in Table 1. Spent process streams in catalyst manufacturing facilities also contain precious metals such as Ag, Pt, and Pd. Developing an effective recovery process of these metal ions for reuse is important.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2012.11a
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• pp.17-17
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• 2012

Magnesium alloys exhibit many attractive properties such as low density, high strength/weight ratio, high thermal conductivity, very good electromagnetic features and good recyclability. However, most commercial magnesium alloys require protective coatings because of their poor corrosion resistance. Attempts have been made to improve the corrosion resistance of the Mg alloys by surface treatments, such as chemical conversion coatings, anodizing, plating and metal coatings, are commonly applied to magnesium alloys in order to increase the corrosion resistance. Among them, chemical conversion coatings are regarded as one of the most effective and cheapest ways to prevent corrosion resistance. In this study, zinc phosphate conversion coatings on various Mg alloys have been developed by selecting proper phosphating bath composition and concentration and by optimizing phosphating time, temperature. Morphology, coatings composition, corrosion resistance, adhesion and its formation and growth mechanism of the zinc phosphate conversion coatings were studied. Results have shown some attractive properties such as simplicity in operation, significantly increased corrosion protective property. However, adhesions between coatings and substrate and also between coatings and paint are still not satisfied. Resolving the problems and understanding the mechanism of phosphating process are targets of our study.

• Journal of Surface Science and Engineering
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• v.20 no.3
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• pp.118-126
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• 1987

The Zn-Al composite electroplating was studied by using chloride zinc bath containing metal hydroxides $(Zn(OH)_2,\;Al(OH)_3))$ and aluminium powder. The size of Al powder codeposited in the beaker bath with Al powder of-400 mesh was under 10${\mu}m$. The Zn-Al composite was electro-deposited at 40$^{\circ}C$ in the ranges of current density of 5-50 A/$dm^2$ in the flowing electrolyte. The content of aluminium particles codeposited increased slightly with increasing flow rate of electrolyte from 0.5 m/sec to 1.0 m/sec, and decreased with increasing current density from 5 A/$dm^2$ to 50 A/$dm^2$. The content of aluminium particles codeposited by using the electrolyte containing zinc hydroxide(0.1M) was 2~4 wt%. The Al powder was codeposited mainly near the surface layer of the electrodeposits. The dissolution rate of aluminium particles in the electrolyte containing 0.1M $Zn(OH)_2$ and Boric acid was 0.41 g/l. day in comparison with 1.5 g/l. day dissolution rate in pure chloride bath.

• Korean Journal of Materials Research
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• v.5 no.7
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• pp.794-801
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• 1995

To connect the driver IC and Al coated glass, a method has been developed to plate electrolessly Ni on Al/PR system. It Is necessary to pretreat Al to remove oxide film before plating. In order to find pretreatment process which does not damage photoresist or glass, alkaline and fluoride zincate process have been investigated. Because photoresist and aluminum thin film can easily dissolve in alkaline solution, it is considered that the fluoride zincate process was a suitable one. After immersion in the zincate solution containing 1.5 g/$\ell$ ammonium bifluoride and 100 g/$\ell$ zinc sulfate, electroless nickel plating could be performed. The additive in the zincate solution and thiourea in the plating solution increased smoothness of the plated surface. Acld dip could improve the uniformit of the surface.

• Applied Chemistry for Engineering
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• v.18 no.3
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• pp.296-302
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• 2007

A trivalent chromate conversion coating solution which is composed with $KCr_2(SO_4)$ as main component was investigated to test a feasibility of use as an alternative six-valent chromate conversion coating for improvement of anti-corrosion of zinc plating. The proposed trivalent convesion coating was consisted of $KCr(SO_4)$ 35~45 g/L as trivalent chromium source, $NaH_2PO_4$ 20~30 g/L as phosphate, $CoSO_4$, 10~20 g/L, $ZnSO_4$ 10~20 g/L as metallic sulfates. This trivalent chromate films which are coated by this chromate conversion coating solution under pH 2.0~2.2, immersion time of 20~25 s at room temperature are able to achieve over 120 h in neutral salt spray test to 5% white rust.

• Journal of Adhesion and Interface
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• v.4 no.3
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• pp.1-8
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• 2003

Adhesion between rubber compound and copper-film-coated steel plate (abbreviated hereafter as copper film plate) with different thicknesses of copper film was investigated. Two different methods were employed for the preparation of the copper film plates: a substitution plating of preelectroplated zinc with copper ion and a vacuum sputtering of copper on steel plate. Adhesion strength of the copper film plates with rubber compounds was largely dependent upon the thickness of copper film, regardless of their preparation methods. The copper film plates with thinner thickness than 75 nm showed high adhesion comparable to brass, while those with thicker copper film showed poor adhesion due to excessive growth of copper sulfide at adhesion interface.

• Corrosion Science and Technology
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• v.18 no.3
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• pp.86-91
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• 2019

Generally, atmospheric corrosion is the electrochemical degradation of metal that can be caused by various corrosion factors of atmospheric components and weather, as well as air pollutants. Specifically, moisture and particles of sea salt and sulfur dioxide are major factors in atmospheric corrosion. Using galvanized steel is one of the most efficient ways to protect iron from corrosion by zinc plating on the surface of the iron. Galvanized steel is widely used in automobiles, building structures, roofing, and other industrial structures due to their high corrosion resistance relative to iron. The atmospheric corrosion of galvanized steel shows complex corrosion behavior, depending on the plating, coating thickness, atmospheric environment, and air pollutants. In addition, corrosion products are produced in different types of environments. The lifespans of galvanized steels may vary depending on the use environment. Therefore, this study investigated the corrosion behavior of galvannealed steel under atmospheric corrosion in two locations in Korea, and the lifespan prediction of galvannealed steel in rural and coastal environments was conducted by means of the potentiostatic dissolution test and the chemical cyclic corrosion test.

• Corrosion Science and Technology
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• v.17 no.5
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• pp.231-241
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• 2018

Atmospheric corrosion is generally an electrochemical degradation process of metal. It can be caused by various corrosion factors of atmospheric component, weather, and air pollutants. Moisture, particles of sea salts, and sulfur dioxide are major factors in atmospheric corrosion. Galvanizing coating is one of the most efficient ways to protect iron from corrosion by zinc plating on the surface of the iron. Galvanized steels are being widely used in automobiles, building structures, roofing, and other industrial structures due to their high corrosion resistance compared to bare iron. Atmospheric corrosion of galvanized steel has shown complex corrosion behavior depending on coating process, coating thickness, atmospheric environment, and air pollutants. In addition, different types and kinds of corrosion products can be produced depending on the environment. Lifespan of galvanized steels is also affected by the environment. Therefore, the objective of this study was to determine the corrosion behavior of galvanized steel under atmospheric corrosion at six locations in Korea. When the exposure time was increased, content of zinc from GA surface decreased while contents of iron and oxygen tended to increase. On the other hand, content of iron was constant even after 36 months of exposure of GI.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.10
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• pp.603-610
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• 2017

Steel used for various industrial fields including ammunition is vulnerable to corrosion so surface treatments are required such as plating, painting and chemical conversion coating. Zinc phosphate, used for ammunition manufacturing, is used to stick the stable compound on the surface by chemical conversion of metal. The quality of phosphate coating depends on many factors such as total acidity and iron content. In this study, we studied the influence of total acidity and iron content on coating weight and corrosion resistance of phosphate coating. The surface structure of the coating becomes dense and corrosion resistance is improved with increasing iron content. However, total acidity influences only the thickness and phosphate coating weight. In conclusion, this study suggests the optimal range of total acidity and iron content to manufacture the ammunition.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2003.10a
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• pp.140-143
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• 2003

The drawbead is an important part in sheet metal forming for automotive part and its effect is affected by various process parameters. Therefore in this study, drawbead friction test was performed at various process parameters - panels (cold rolled and galvanized sheet steel), lubricants (having three different viscosities), bead materials(steel, iron) and surface treatment of bead (Cr plating). Circular shape bead has been used for the test. The results show that friction and drawing characteristics were mainly influenced by the nature of zinc coating, viscosity of lubricants, surface treatment of a bead and hardness of coated layer.