• Corrosion Science and Technology
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• 제17권5호
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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.

• 상하수도학회지
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• 제22권3호
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• pp.379-387
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• 2008

The pH & alkalinity adjustment method by lime and carbon dioxide($CO_2$) for corrosion control in water distribution system was investigated to evaluate the corrosion characteristics of metal pipes, such as galvanized iron, copper, stainless steel, and carbon steel. When the pH in sand filtered and ozone+GAC treated water was increased with lime and $CO_2$ from 7.5 to 8.0, the concentration of residual chlorine decreased at higher pH and longer reaction time; the concentration of trihalomethane increased. The corrosion rate of coupons with corrosion control using lime and carbon dioxide was showed much smaller than those without corrosion control using pilot-scale simulated distribution system. The galvanized iron was corroded much faster than carbon steel, copper, and stainless steel. Especially, copper and stainless steel coupons were hardly corroded. The galvanized iron and carbon steel coupons with corrosion control were produced the corrosion products less than those without corrosion control by the results of environmental scanning electron microscope(ESEM) and energy dispersive x-ray spectroscopy(EDS) analyses. The galvanized iron coupon with pH and alkalinity adjustment by lime and carbon dioxide was detected about 30 percent of zinc, when the carbon steel was detected about 30 percent of calcium by calcium carbonate products formation. For the results of X-ray diffraction(XRD) analyses, the goethite(${\alpha}$-FeOOH) was identified as primary corrosion product of galvanized iron without corrosion control, while the Zinc oxide(ZnO) was found on corrosion products of galvanized iron coupon with corrosion control as the results of EDS analyses. However, the carbon steel corrosion products regardless of corrosion control were composed predominantly of maghemite(${\gamma}-Fe_2O_3$) and hematite(${\alpha}-Fe_2O_3$).

• 한국환경과학회지
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• 제9권6호
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• pp.505-509
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• 2000

The purpose of this study was to evaluate the effects of $Ca(OH)_2$ and $CO_2$ additions on the corrosion of metal coupons(ductile iron, galvanized steel, copper and stainless steel). Corrosion rate and released metal ion concentration of ductile iron and galvanized steel decreased by adjusting alkalinity, calcium hardness and pH with $Ca(OH)_2$ & $CO_2$ additions on copper and stainless steel were less than those on ductile iron and galvanized steel. When ductile iron coupon was exposed to water treated with Ca(OH)$_2$&$CO_2$, additions, the main components of corrosion product formed on its surface were $CaCO_3$ and $Fe_2 O_3 or Fe_2 O_4$ which often reduce the corrosion rate by prohibiting oxygen transport to the metal surface.

• Corrosion Science and Technology
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• 제18권3호
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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.

• 미생물학회지
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• 제31권3호
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• pp.255-260
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• 1993

Enterobacter cloacae 를 이용하여 슬라이드 (slide glass) 와 아연도강관조각 (galvanized-iron coupon) 상에 생물막을 형성시킨 후 부착생장세균의 염소에 대한 내성을 측정한 결과 부유생장세균에 비해 각각 14배와 380배의 내성증가를 나타내었다. 또한 입자에 부착된 세균군집의 경우 부유세균군집에 비해 48배로 내성이 증가되었다. 슬라이드와 아연도강관조각을 수돗물에 75일간 접촉하였을때 각각 $4.75 {\times} 10^{4}$ cfu/$cm^{2}$, $1.12 {\times} 10^5 cfu/cm^{2}$의 생물막이 형성되는 것을 관찰하였다. 따라서 수돗물에서의 장내세균과 종속영양세균 입자에 부착 혹은 흡착되거나 응집된 상태로 존재함으로써 잔류염소에 대한 내성을 가지게 되며, 또한 정수과정에서 염소살균을 피하여 비급수계통으로 유입되면 배급수관 내벽에 생물막을 형성하여 잔류업소에 대한 내성을 가지게 됨으로써 배급수계통에서 생장하는 것으로 판단된다.

• 한국표면공학회지
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• 제31권2호
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• pp.101-108
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• 1998

The effect of oxidation-reduction heating conditions on coating adherence of hot-dip galvanized steel containing silicon has beeninvestigated. The presence of a stbke sillicon oxide formed on the steel surface has been shown to be very detrimenal to proper wetting by liquid zinc. When the steel has more than the critical sillicon content neeled to from a stable external oxide, the use of oxidation-reduction method has been found successful in obtaining a good quality, coated product with excellence adhreence. This can be explained by the formation of an iron oxide. The iron oxrtion of the scale is reduced, leaving the stable oxides dispersed in a fresh metallic iron surface layer. This reduced iron surface is easily wetted by the liquid zinc and excellent adherence is obtained.

• 한국기계가공학회지
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• 제15권1호
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• pp.110-115
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• 2016

The need for high-strength galvanized steel has recently increased because of the increased number of car consumers who want improved efficiency and exterior quality. High-strength galvanized steel with high corrosion resistance improves the durability of products and exterior quality. Furthermore, the gilt of zinc does not come off during machining because of the fine adhesive property of zinc. When these are welded, zinc has a lower melting temperature than iron, so zinc is more quickly vaporized than iron. Vaporized zinc can stick to electrodes, which increases spatter in welding transportation. Created spatter can enter the molten pool and develop into inner defects or blowholes and pits. Scattered spatter sticks to the product, which leads to the secondary cost of spatter removal. Therefore, in this study, comparisons of amounts of spatter generated are conducted according to the composition of shielding gas in the MIG and CMT processes to find optimal welding parameters.

• 한국환경보건학회지
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• 제32권5호
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• pp.431-439
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• 2006

This research was conducted using a model home plumbing system composed of copper, stainless steel, galvanized iron, carbon steel, and PVC (polyvinyl chloride) pipe. The number of bacteria present in stainless steel pipe and PVC was higher than other pipes. High turbidity and zinc release were found in galvanized iron pipe material and detected during the first 6 months. Conversely, there was a decrease in turbidity and zinc release after 6 months resulting in levels similar to other pipes. Copper concentration decreased as operation times increased. In this experiment, the number of bacteria detected in biofilm for a copper pipe continued to increase. Pipe material influenced bacterial numbers in biofilm and water. This showed that elevated chlorine could not control bacterial growth in biofilm for galvanized iron and stainless steel systems. It also suggested that the dosing of chlorine might not be available for all kinds of pipes. Therefore, another complementary method should be introduced to manage biofilm effectively in water distribution systems.

• 자원리싸이클링
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• 제9권1호
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• pp.15-20
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• 2000

Zn을 많이 함유하는 銅scrap(자동차용강판, Zn표면처리강판 등)을 이용하여 구상흑연주철을 제조한 경우 구상화가 제대로 이루어 지지 않았다. Sb을 많이 함유하는 銅scrap을 이용하여 구상흑연주칠을 제조한 경우에는 기지 층의 퍼얼라이트량이 증가하였다. 퍼얼라이트량이 증가하면 인장강도 및 경도는 증가하지만 연산율은 감소하였다. Mn, Cr을 많이 함유한 銅scrap(기계구조용강판, 가단주철)을 이용하여 구상흑연주출을 제조한 경우에는 피얼라이트량이 증가하였으며, 인장강도 및 경도도 증가하였다.

• 한국전기화학회:학술대회논문집
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• 한국전기화학회 2000년도 추계총회 및 학술발표회
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• pp.15-15
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• 2000