• Title, Summary, Keyword: corrosion resistance

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Effect of the Specific Resistance of Water on Corrosion Characteristics of STS 304 for Gas Boiler (가스보일러용 STS 304의 부식특성에 미치는 용수의 비저항의 영향)

  • Lim, Uh-Joh;Kim, Hwan-Sik;Yun, Byoung-Du
    • Journal of Fisheries and Marine Sciences Education
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    • v.19 no.3
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    • pp.323-328
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    • 2007
  • This paper was studied on the effect of the specific resistance of water on corrosion characteristics of STS 304 for gas boiler. The electrochemical polarization test of STS 304 for gas boiler was carried out. And the polarization resistance, uniform corrosion, corrosion behavior by impressed potential and corrosion sensitivity of STS 304 with specific resistance were considered. The main results are as following: 1) With being low the specific resistance of water, the polarization resistance and corrosion potential of STS 304 decreases, while corrosion current density increases. 2) Under constant impressed potential, the corrosion sensitivity of STS 304 is large with being low the specific resistance due to synergy effect of Cl ion.

Electrochemical Evaluation on Corrosion Resistance of Anti-corrosive Paints

  • Moon, Kyung-Man;Lee, Myung-Hoon;Kim, Yun-Hae
    • Journal of the Korean Society of Marine Engineering
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    • v.33 no.3
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    • pp.387-394
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    • 2009
  • It has been observed that coated steel structures are rapidly deteriorated than designed lifetime due to acid rain caused by air pollution etc.. Therefore improvement of corrosion resistance of anti-corrosive paint is very important in terms of safety and economic point of view. In this study corrosion resistance for five kinds of anti-corrosive paints including acryl, fluorine and epoxy resin series were investigated with electrochemical methods such as corrosion potential, polarization curves, impedance and cyclic voltammogram measurements etc.. There were somewhat good relationships between values measured by electrochemical methods such as corrosion current density obtained by cathodic and anodic polarization curves, value of impedance estimated with AC impedance, and polarization resistance on the cyclic voltammogram, for example, corrosion current density was decreased with increasing of values of impedance and polarization resistance on the cyclic voltammogram. However their relationships between corrosion current density and corrosion potential were not well coincided each other. Consequently it is considered that although a corrosion potential of F101 of fuoric resin series shifted to negative direction than other anti-corrosive paints, its corrosion resistance, indicating on the cathodic and anodic polarization curves, AC impedance curves and cyclic voltammogram, was the most superior to other paints, whereas A100 containing arcylic resin showed a relatively poor corrosion resistance compared to other paints.

Effects of phosphate coating on some performance of painted Al alloy sheet (도장 알루미늄 합금판의 성능에 미치는 인산염피막의 영향)

  • 이규환;노병호
    • Journal of the Korean institute of surface engineering
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    • v.28 no.5
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    • pp.289-299
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    • 1995
  • The effects of phosphate coating have been studied on physical properties and corrosion resistance of painted aluminum alloy sheet for automobile body. The physical properties (surface roughness, paint adhesion, impact resistance and pencil hardness) and corrosion resistance(cyclic corrosion and filiform corrosion) were investigated. Phosphate coatings enhanced the physical properties of painted Al alloy sheet, especially paint adhesion after the 240hours water immersion test. Phosphate coating also markedly improved the resistance for cyclic corrosion and filiform corrosion of painted cold rolled steel and Zn-Ni plated steel sheet as well as painted Al alloy sheet. The corrosion resistance of painted Al sheets was varied with the concentration of free fluoride ion and metal additives like Ni and Mn in the phosphating bath. A maximum corrosion resistance was obtained at about 300ppm of fluoride ion and additives of Ni and Mn obviously increased the corrosion resistance of painted specimens.

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A Study on Corrosion Resistance of Reinforced Concrete Structures using Natural Inorganic Minerals (천연 무기 광물계 혼화재료를 혼입한 철근콘크리트 구조물의 부식저항성에 관한 연구)

  • Tae, Sung Ho;Park, Jae Young;Kim, Jae Young;Park, Jae Seung;Kyung, Je Woon;Nam, Ho Yoon
    • KIEAE Journal
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    • v.7 no.4
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    • pp.127-133
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    • 2007
  • As a fundamental study on the corrosion resistance of reinforced concrete structures using Natural Inorganic Minerals exposed to carbonation environment, The test specimens were concrete(W/C=60%) with Natural Inorganic Minerals content of 0%, 10%. Accelerated carbonation and autoclave corrosion accelerated curing were then conducted with them. The corrosion resistance of steel in concrete with Natural Inorganic Minerals content of 0%, 10% was examined by corrosion form, half-cell potential, polarization resistance, corrosion area and weight loss after 24 hours of autoclave corrosion accelerated curing.The results of the study showed that as for steel in concrete with Natural Inorganic Minerals content of 10%, the corrosion resistance was more excellent than steel in concrete with Natural Inorganic Minerals content of 0%.

Magnesium Thin Films Possessing New Corrosion Resistance by RF Magnetron Sputtering Method

  • Lee, M.H.;Yun, Y.S.;Kim, K.J.;Moon, K.M.;Bae, I.Y.
    • Corrosion Science and Technology
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    • v.3 no.4
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    • pp.148-153
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    • 2004
  • Magnesium thin flims were prepared on cold-rolled steel substrates by RF magnetron sputtering technique. The influence of argon gas pressure and substrate bias voltage on their crystal orientation and morphology of the coated films were investigated by scanning electron microscopy (SEM) and X-ray diffraction, respectively. And the effect of crystal orientation and morphology of magnesium films on corrosion behaviors was estimated by measuring anodic polarization curves in deaerated 3%NaCl solution. From the experimental results, all the sputtered magnesium films showed obviously good corrosion resistance to compare with 99.99% magnesium target of the sputter-evaporation metal. Finally it was shown that the Corrosion-resistance of magnesium films can be improved greatly by controlling the crystal orientation and morphology with effective use of the plasma sputtering technique.

The Capacity of Applying Electrical Resistance Probe in Natural Corrosion Tests of Vietnam

  • Pham, Thy San;Le, Thi Hong Lien;Le, Quoc Hung
    • Corrosion Science and Technology
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    • v.2 no.2
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    • pp.98-101
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    • 2003
  • The Electrical Resistance Probe of carbon steel and weight loss coupons were exposed in atmosphere and in the lake water of Hanoi. The comparison of data received by two methods after one year exposure was presented. The correspondence of the data of these methods on the exposure time in both environments showed a capacity of using Electrical Resistance Probe in Vietnamese natural corrosion testing of Carbon steel.

An Electrochemical Evaluation on the Corrosion Resistance of a Al Alloy (주조용 Al합금의 내식성에 관한 전기화학적 평가)

  • Youn Dae-Hyun;Lee Myung-Hoon;Kim Ki-Joon;Moon Kyung-Man
    • Journal of the Korean Society of Marine Engineering
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    • v.29 no.5
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    • pp.495-501
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    • 2005
  • Al is a active metal that owes its resistance to a thin, protective, barrier oxide surface layer, which is stable in air and neutral aqueous solution. Thus Al alloys are widely used in architectural trim. cold & hot-water storage vessels and piping. However Al and most of its alloy may corrode with some forms such as pitting corrosion, intergranular corrosion and galvanic corrosion in the case of exposure to various industrial and marine atmosphere. Therefore a correct evaluation of corrosion resistance for their Al and Al alloys may be more important in a economical point of view. In this study. a relative evaluation of corrosion resistance for three kinds of Al alloys such as ALDC2, ALDC3, and ALDC8 series was carried out with electrochemical method. There is a tendency that corrosion potential is shifted to positive or negative direction by alloying components regardless of corrosion resistance. Moreover the data of corrosion properties obtained from cathodic Polarization curve, cyclic voltammogram and AC. DC impedance respectively showed a good correspondence each other against the corrosion resistance but variation of corrosion potential. passivity current density of anodic polarization curve and corrosion current density by Tafel extrapolation and Stern-Geary method didn't correspond with not only each other but also considerably the data of corrosion properties discussed above. Therefore it is suggested that an optimum electrochemical evaluation for corrosion resistance of Al alloy is to calculate the diffusion limiting current density of cathodic polarization curve, impedance of AC or DC and polarization resistance of cyclic voltammogram.

Intepretation of Faradaic Impedance for Corrosion Monitoring

  • Itagaki, M.;Taya, A.;Imamura, M.;Saruwatari, R.;Watanabe, K.
    • Corrosion Science and Technology
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    • v.3 no.1
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    • pp.1-5
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    • 2004
  • A polarization resistance is generally used to estimate the corrosion rate in the corrosion monitoring by an electrochemical impedance method. When the Faradaic impedance has a time constant due to the reaction intermediate, the electrochemical impedance describes more than one loop on the complex plane. For example, the electrochemical impedance of iron in acidic solution shows capacitive and inductive loops on the complex plane. In this case, the charge transfer resistance and the polarization resistance are determined at middle and low frequency ranges, respectively. Which should be selected for corrosion resistance in corrosion monitoring, the charge transfer resistance or the polarization resistance'? In the present paper, the above-mentioned question is examined theoretically and experimentally.

Corrosion Resistance of SD460 Reinforcing Rod by Ceramic Coating (SD460 철근의 세라믹 코팅에 의한 내식성 향상연구)

  • Park, Ki Y.;Lee, Jong K.;Hong, Seok W.
    • Corrosion Science and Technology
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    • v.8 no.4
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    • pp.157-161
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    • 2009
  • The corrosion resistance of reinforcing bar was studied to endure the marine environment during shipment. The red rust on the surface did not damage the adherence in the concrete structures, especially in highly alkaline environment, but made the consumer doubt of the quality. The passivation process by alkalization of the quenching water in the tempcore process failed to endure the long shipping period. The ceramic coating by sol-gel process improved the corrosion resistance without damaging the mechanical properties and adherence between concrete and reinfiorcing bar. Optimal concentration of the coating solution and coating temperature were tested. No additional energy was necessary for the coating process by spraying during cooling process, resulting simplified process and low cost. Salt spray test, cyclic corrosion test and atmospheric test were employed to confirm the resistance. The corrosion rates were presented by rating number and polarization resistance. The coating layer was examined by FIB, XRD and SEM etc.

Corrosion Resistance of the Roll Formed Steel Bolts with the Various Types of Coating Methods (1) (다양한 코팅 방법에 따른 전조한 강 볼트의 내부식성 (1))

  • Mamatov, S.;Hamrakulov, B.;Son, Y.H.;Kim, I.
    • Transactions of Materials Processing
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    • v.28 no.2
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    • pp.71-76
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    • 2019
  • Corrosion resistance is one of the essential properties required in steel bolts. The various types of coatings are used to improve the corrosion resistance of steel bolts. But, roll formed, subsequently Zn alloy electrodeposited and top coated steel bolt easily takes place the white storage stain or white rust under high humidity condition. To investigate the corrosion resistance of roll formed and subsequently the various types of coated steel bolts, their polarization curves were measured by potentio-dynamic tester in this study. Based on the measured polarization curves, the more times of chromate and top coating on roll formed steel bolt, the higher corrosion resistance was shown. The roll formed steel bolt, which was Zn-Ni electro-deposited, two times chromated, one time inorganic top coated, one time organic top coated and annealed, showed the best corrosion resistance.