• Corrosion Science and Technology
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• v.22 no.2
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• pp.99-107
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• 2023

Layered silicate clay montmorillonite (MMT) has been used in nanocomposite coating to improve corrosion protection by reinforcing the barrier property. The better dispersion of MMT in the coating produces a higher barrier effect. Pretreatment with MMT could favor the delamination of clay platelets, facilitating MMT dispersion in the coating. In the present work, a montmorillonite/silica (MMT/Si) composite was prepared by the in situ sol-gel method. x-ray diffraction measurements and field-emission scanning electron microscopy observations showed silica crystal formation and increased basal spacing between the MMT platelets. Composite MMT/Si particles were introduced in an epoxy resin to reinforce the corrosion protection of the coating applied on the AA2024 surface. Electrochemical impedance spectroscopy (EIS) was performed to characterize the protective property of the coating. The results demonstrated the high barrier effect of the coating containing 5 wt% of MMT/Si. Adhesion evaluation after a salt spray test exhibited a high adherence to the epoxy coating containing MMT/Si.

• Corrosion Science and Technology
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• v.20 no.6
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• pp.335-346
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• 2021

Since epoxy resin coating shows excellent properties in formability, adhesion, and corrosion resistance, they have been extensively used in many industries. However, various types of damages in the epoxy coated tube within a relative short time have been reported due to cavitation erosion, liquid impingement, variation of temperature and pressure. Nevertheless, there has been little research on the effect of temperature on the cavitation degradation of epoxy coatings. Therefore, this work used an ultrasonic cavitation tester to focus on the effect of solution temperature on the cavitation properties of 3 kinds of epoxy coatings in 3.5% NaCl. The cavitation properties were discussed basis on the material properties and environmental aspects. As the solution temperature increased, even though with large fluctuation, the cavitation degradation rates of A and B coatings were reduced rapidly, but the rate of C coating was decreased gradually. In addition to the cushioning effect, the reason that the cavitation degradation rate reduced with solution temperature was partly related to the brittle fracture and water absorptivity of the epoxy coatings, and the water density, but was little related to the shape and composition of the compound in the coatings or the phase transition of the epoxy coating.

• Corrosion Science and Technology
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• v.21 no.2
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• pp.111-120
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• 2022

To solve the corrosion problem of industrial equipment and other constructions containing metals, corrosion protection can be performed by using coating which provides a barrier between the metal and its environment. Coatings play a significant role in protecting irons and steels in harsh marine and acid environments. This study was conducted to identify an anti-corrosive epoxy coating for carbon steel composite with 0.1, 0.3, and 0.5 wt% concentrations of nanoparticles of SiO₂ using the dip-coating method. The electrochemical behavior was analyzed with open circuit potential (OCP) technics and polarization curves (Tafle) in 3.5 wt% NaCl and 5 vol% H₂SO₄ media. The structure, composition, and morphology were characterized using different analytical techniques such as X-ray Diffraction (XRD), Fourier Transform Infrared spectrum (FT-IR), and Scanning Electron Microscopy (SEM). Results revealed that epoxynano SiO₂ coating demonstrated a lower corrosion rate of 2.51 × 10^-4 mm/year and the efficiency of corrosion protection was as high as 99.77%. The electrochemical measurement showed that the nano-SiO₂ / epoxy coating enhanced the anti-corrosive performance in both NaCl and H₂SO₄ media.

• Applied Chemistry for Engineering
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• v.16 no.6
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• pp.809-814
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• 2005

In this work, the thermal properties of epoxy coating system on the liner plate in the containment structure of nuclear power plants had been examined by irradiation and design basis accident (DBA) conditions. The effect of immersion in hot water on adhesion strength of the coating system had been also studied. The glass transition temperature ($T_g$) and thermal stability of ET-5290/carbon steel A 32 epoxy coating systems were measured by DSC and TGA analyses, respectively. Contact angle measurements were used to determine the effect of immersion on the surface energetics of epoxy coating system, with a viewpoint of surface free energy. Adhesion tests were also executed to evaluate the adhesion strength at interfaces between carbon steel plate and epoxy resins. As a result, it was found that the irradiation led to an improvement of internal crosslinked structure in cured epoxy systems, resulting in significantly increasing the thermal stability, as well as the $T_g$. Also, the immersion in hot water made a role in the post-curing of epoxy resins and increased the mechanical interlocking of the network system, resulting in increasing the adhesion strength of the epoxy coating system.

• Journal of the Korea Institute of Building Construction
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• v.3 no.1
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• pp.93-105
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• 2003

The Precast Concrete(PC) method was developed for a large production of a structure in Europe. Afterwards, this PC method has been applied to a structure and an outside Coating of buildings extensively. The outside Coating of the building applied this PC method is a method to put tiles or stones to base concrete. And there is a method to use paints for, so the expression of various patterns is possible. The Multi-Layer Coating is one of the methods to use paints. This Multi-Layer Coating method can show various designs of external appearance with Foam when it is made with the PC panel. Also, the paint film of the PC panel enables a splendid appearance, and a protective function of concrete is possible, too. Therefore, it makes good durability of the PC. Besides, maintenance is easy to manage because it is free from pollution when it uses metallic materials, stones, or any other materials. You might have no trouble in applying the Multi-Layer Coating method in order to save a merit of an outside Coating on the PC panel. However, the Multi-Layer Coating method used as a current outside Coating method has pollution and bad working environment because Oil Epoxy Resins have toxicity and flammability. Therefore, a lot of warnings are required for coating work in order to have appropriate quality because working hours are short, and production efficiency is low too. These reasons make the cost of construction of the Multi-Layer Coating method increase. And employers or designers may have problems in selecting this Multi-Layer Coating method. Therefore, the purpose of this study is to get activation of the Multi-Layer Coating method by offering improvement measures about the problems of the existing Multi-Layer Coating method.

• Proceedings of the Korea Concrete Institute Conference
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• 1990.10a
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• pp.79-82
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• 1990

The results of a large-scale study to determine the effects of epoxy coating on the bond strength between deformed reinforcement and concrete are descrebed. Tests include beam-end specimens containing No. 5(16mm), No. 6 (19mm), No. 8(25mm), No. 11(32mm) bars with average coating thicknesses ranging from 3 to 17 mils(0.08-0.43mm). Three deformation patterns are evaluated. Specimens with covers of 1, 2, and 3 bar deameters are studied. Both top-cast and bottom-cast bars are tested. Epoxy coatings are found to significantly reduce bond strength. The severity of that reduction is a function of deformation pattern, bar size, and coating thickness. Design recommendations based on these observations differ from the modifications to the 1989 ACI Building Code.

• Corrosion Science and Technology
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• v.20 no.1
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• pp.26-36
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• 2021

Pipes operating in the seawater environment faces cavitation degradation and corrosion of the metallic component, as well as a negative synergistic effect. Cavitation degradation shows the mechanism by which materials deteriorate by causing rapid change of pressure or high-frequency vibration in the solution, and introducing the formation and explosion of bubbles. In order to rate the cavitation resistance of materials, constant conditions have been used. However, while a dynamic cavitation condition can be generated in a real system, there has been little reported on the effect of ultrasonic amplitude on the cavitation resistance and mechanism of composites. In this work, 3 kinds of epoxy coatings were used, and the cavitation resistance of the epoxy coatings was evaluated in 3.5% NaCl at 15 ℃ using an indirect ultrasonic cavitation method. Eleven kinds of mechanical properties were obtained, namely compressive strength, flexural strength and modulus, tensile strength and elongation, Shore D hardness, water absorptivity, impact test, wear test for coating only and pull-off strength for epoxy coating/carbon steel or epoxy coating/rubber/carbon steel. The cavitation erosion mechanism of epoxy coatings was discussed on the basis of the mechanical properties and the effect of ultrasonic amplitude on the degradation of coatings.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2008.06a
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• pp.191-192
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• 2008

• Corrosion Science and Technology
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• v.8 no.2
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• pp.68-73
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• 2009

An evaluation of underwater - repair coating materials was based on the premise that defective areas of the existent epoxy coating such as blistering and cracking will be repaired on spot under submerged condition. Tests include the clarification as to whether they are compatible between as-built coating and new repair coating on each concrete specimen. Candidate coating materials for repair were tested in a laboratory to scrutinize their suitability to perform the needed function satisfactorily. The qualification tests performed are as a minimum as follows: Integrated radiation tolerance test, chemical resistance test (submerged condition in deionized water), hardness test and adhesion test of the repair materials. The proper repair coating materials were selected and approved from this test results.

• Magazine of the Korean Society of Agricultural Engineers
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• v.25 no.2
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• pp.67-75
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• 1983

The objectives of this paper were to measure the bond strengths of reinforced concrete in which the steel rods were coated with five different kinds of anticorrosion paints, and to compare their prevention effects in salt water. The paints used in the study were epoxy resin I . II . III, Z.R. P., and silicone resin, which were applied at rates recommended by the manufacturers. The bond strengths were measured on the 7-, 14-, and 28-th days after molding. Corrosion conditions of coated steel plate under fresh water, seawater, 10 % salt water, and 20% salt water, were inspected every month during four months test peoriods, respectively. The results obtained from tests are summarized as follows: 1. Paint-coating may reduce the bond strengths of reinforced concrete. Silicone resin paint showed some 20% reduction in the strength compared to those without the paint. However, the other paints seemed not to significantly affect the strength. 2. Picture analyses showed that epoxy resin I and II significantly prevented corrosion steel plates in seawater. Epoxy resin I and silicone resin coating did not do a good job in corrosion prevention. Z.R. P. paint was found to be moderate as preventive coating paint. 3. Varying soluble salt contents had little effects on the corrosion prevention of tested paints. 4. Epoxy resin I and II were found to be appropriate as a coating material to prevent the corrosion of steel rods in seawater. Z.R.P. may also be used for the purpose.