• Corrosion Science and Technology
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• v.7 no.5
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• pp.243-251
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• 2008

Magnesium alloys become popular research topic in last decade due to its light weight and relatively high strength-to-weight ratio in the energy aspiration age. Almost all structure materials are supposed to suspend stress. Magnesium is quite sensitive to corrosive environment, and also sensitive to environmental assisted cracking. However, so far we have the limited knowledge about the environmental sensitive cracking of magnesium alloys. The corrosion fatigue (CF) test was conducted. Many factors' effects, like grain size, texture, heat treatment, loading frequency, stress ratio, strain rate, chemical composition of environment, pH value, relative humidity were investigated. The results showed that all these factors had obvious influence on the crack initiation and propagation. Especially the dependence of CF life on pH value and frequency is quite different to the other traditional structural metallic materials. In order to interpret the results, the electrochemistry tests by polarization dynamic curve and electrochemical impedance spectroscopy were conducted with and without stress. The corrosion of magnesium alloys was also studied by in-situ observation in environmental scanning electron microscopy (ESEM). The corrosion rate changed with the wetting time during the initial corrosion process. The pre-charging of hydrogen caused crack initiated at $\beta$ phase, and with the increase of wetting time the crack propagated, implying that hydrogen produced by corrosion reaction participated in the process.

• Journal of the Mineralogical Society of Korea
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• v.26 no.4
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• pp.219-228
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• 2013

To understand characteristics of biogeochemical corrosion for the metal canisters that usually contain the radioactive wastes for a long-term period below the ground, some metal materials consisting of cast iron and copper were reacted for 3 months with D. desulfuricans, a sulfate-reducing bacterium, under a reducing condition. During the experiment, concentrations of dissolved metal ions were periodically measured, and then metal specimen and surface secondary products were examined using the electron microscopy to know the chemical and mineralogical changes of the original metal samples. The metal corrosion was not noticeable at the absence of D. desulfuricans, but it was relatively greater at the presence of the bacterium. In our experiment, darkish metal sulfides such as mackinawite and copper sulfide were the final products of biogeochemical metal corrosion, and they were easily scaled off the original specimen and suspended as colloids. For the copper specimen, in particular, there appeared an accelerated corrosion of copper in the presence of dissolved iron and bacteria in solution, probably due to a weakening of copper-copper binding caused by a growth of other phase, iron sulfide, on the copper surface.

• Smart Structures and Systems
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• v.26 no.4
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• pp.507-520
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• 2020

In order to achieve effective corrosion monitoring of buried metal pipelines, a Novel nondestructive Testing (NDT) methodology using ultra-long (250 mm) Polymer Optical Fiber (POF) sensors coated with the Fe-C alloy film is proposed in this study. The theoretical principle is investigated to clarify the monitoring mechanism of this method, and the detailed fabrication process of this novel POF sensor is presented. To validate the feasibility of this novel POF sensor, exploratory research of the proposed method was performed using simulated corrosion tests. For simplicity, the geometric shape of the buried pipeline was simulated as a round hot-rolled plain steel bar. A thin nickel layer was applied as the inner plated layer, and the Fe-C alloy film was coated using an electroless plating technique to precisely control the thickness of the alloy film. In the end, systematic sensitivity analysis on corrosion severity was further performed with experimental studies on three sensors fabricated with different metal layer thicknesses of 25 ㎛, 30 ㎛ and 35 ㎛. The experimental observation demonstrated that the sensor coated with 25 ㎛ Fe-C alloy film presented the highest effectiveness with the corrosion sensitivity of 0.3364 mV/g at Δm = 9.32 × 10^-4 g in Stage I and 0.0121 mV/g in Stage III. The research findings indicate that the detection accuracy of the novel POF sensor proposed in this study is satisfying. Moreover, the simple fabrication of the high-sensitivity sensor makes it cost-effective and suitable for the on-site corrosion monitoring of buried metal pipelines.

• Corrosion Science and Technology
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• v.21 no.5
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• pp.381-389
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• 2022

Cyclic Voltammetry and weight loss measurements were used to investigate corrosion prevention of tin in a 0.5M citric acid solution containing Anthocyanins extracted from grapes at various concentrations and temperatures. Results showed that the investigated chemicals, Anthocyanins extracted from grapes, performed well as tin corrosion inhibitors in 0.5M citric acid. Increasing the concentration of Anthocyanins increased their corrosion inhibition efficiencies. When the temperature dropped, their inhibition efficiencies, increased indicating that higher temperature tin dissolution predominated the adsorption of Anthocyanins at the surface of tin metal. When inhibitor concentrations were increased, their inhibition efficiencies were also increased. These results revealed that corrosion of tin metal was inhibited by a mixed type of adsorption on the metal surface. The adsorption isotherm of Langmuir governed the adsorption of Anthocyanins. Thermodynamic parameters such as the enthalpy of adsorption, the entropy of adsorption, and Gibbs free energy and kinetic parameters such as activation energy, enthalpy of activation, and entropy of activation were computed and discussed in this study.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2005.05a
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• pp.113-117
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• 2005

The ceramic metal resin paints for waterproof and anti corrosion is not long history in development of materials even many actual result. So far, no standard have been given to construction and maintenance method, Quality and property, it is real state that cannot afford to proper quality control in job site or production. This study has been test for the ceramic metal resin paints for water and anti corrosion, as the result, it have proper performance of job site and mechanical performance of compare to other existing. In particular, tensile strength indicates more high about $14.1N/mm^2$ than epoxy resin paints, and in elongation per unit length is more high It is shows having better adhesive strength than epoxy resin paint for crack on the concrete structure. Moreover, The ceramic metal paint for water and corrosion proofing have to have main performance is watertightness and resistance for external impact, chloride ion permeation, drinkable water elution.

• Journal of Advanced Marine Engineering and Technology
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• v.20 no.2
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• pp.92-92
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• 1996

Recently, with the rapid development in the oceanic systems such as the oceanic structures and vessel, there occurs much interest in the impingement erosion-corrosion. In this paper, Cu-metal was tested by using of erosion apparatus with water-jet type and was investigated under the behaviour of impingement erosion-corrosion according to various environmental conditions, and the properties of Cu-metal were evaluated through the measurement by weight loss, weight loss rate, protective efficiency. The results were compared with those obtained using Cu-metal applied to cathodic protection and Cu-alloys added to Zn or Al-metal. As a basis of those results, the best protective efficiencies could be taken as using cathodic protection method and Cu-alloy with Al & Zn material addings, and will be suggested as the fundamental data of the anti-impingement erosion-corrosion on Cu-metal of impeller material for oceanic centrifugal pump.

• Journal of Advanced Marine Engineering and Technology
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• v.20 no.2
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• pp.24-31
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• 1996

Recently, with the rapid development in the oceanic systems such as the oceanic structures and vessel, there occurs much interest in the impingement erosion-corrosion. In this paper, Cu-metal was tested by using of erosion apparatus with water-jet type and was investigated under the behaviour of impingement erosion-corrosion according to various environmental conditions, and the properties of Cu-metal were evaluated through the measurement by weight loss, weight loss rate, protective efficiency. The results were compared with those obtained using Cu-metal applied to cathodic protection and Cu-alloys added to Zn or Al-metal. As a basis of those results, the best protective efficiencies could be taken as using cathodic protection method and Cu-alloy with Al & Zn material addings, and will be suggested as the fundamental data of the anti-impingement erosion-corrosion on Cu-metal of impeller material for oceanic centrifugal pump.

• Journal of the Korean Society for Heat Treatment
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• v.26 no.6
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• pp.293-299
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• 2013

A specimen of weld metal was prepared by GTA welding with weld wire of super duplex stainless steel. Aging treatment was conducted for the sample at the temperature range of 700 to $900^{\circ}C$ for 5 to 300 minutes. The effect of volume fraction of ${\sigma}$-phase to intergranular corrosion of weld metal has been investigated and the results were derived as follows. The volume fraction of ${\sigma}$ phase tends to increase with an increase of aging temperature and time and intergranular corrosion of weld metal was increased by an increase of ${\sigma}$ phase. Degree of sensitization representing intergranular corrosion was found to tend to increase with an increase of aging time at 700 to $800^{\circ}C$, while it decreased by an increase of aging time at $900^{\circ}C$.

• Journal of Power System Engineering
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• v.19 no.6
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• pp.75-81
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• 2015

A deposited metal specimen of ER2594 which is a super duplex steel welding wire used to investigate the effect of sigma(${\sigma}$) phase on electrochemical corrosion characteristics was prepared by gas tungsten arc welding. Aging treatment was conducted for the specimen at the temperature range of $700^{\circ}C$ to $900^{\circ}C$ for 5 to 300 minutes after annealing at $1050^{\circ}C$. Corrosion current density has decreased a little with an increase of aging time over 60 minutes at $700^{\circ}C$ to $900^{\circ}C$ and the uniform corrosion of deposited metal had more influence on the precipitation of ferrite than the precipitation of sigma phase. Therefore, the precipitation of sigma phase did not have much effect on the uniform corrosion. Pitting potential representing pitting corrosion has shown decreasing tendency as the precipitation of sigma phase increased. The degree of sensitization representing intergranular corrosion has shown increasing tendency as the precipitation of sigma phase increased at $700^{\circ}C$ to $800^{\circ}C$, while it has decreased at $900^{\circ}C$ for 60 to 300 minutes.

• Corrosion Science and Technology
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• v.14 no.6
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• pp.273-279
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• 2015

Effects of passive film quality by chemical passivation and solution flow on the corrosion behavior of 304 stainless steel in HCl solution were investigated using a coloration indicator, and by corrosion weight loss, electrochemical polarization and element dissolution measurements. A high redness degree suggests a low passive-film integrity for 304 stainless steel following air exposure, while the minimum redness degree for the samples after chemical passivation suggests a high passive-film integrity. In the static condition, samples subjected to air exposure exhibited a high corrosion rate and preferential dissolution of Fe. Chemical passivation inhibited the corrosion rate due to the intrinsically high structural integrity of the passive film and high concentrations of Cr-rich oxides and hydroxide. Solution flow accelerated corrosion by promoting both the anodic dissolution reaction and the cathodic reaction. Solution flow also altered the preferential dissolution to fast uniform dissolution of metal elements.