Stochastic Estimation of Acoustic Impedance of Glass-Reinforced Epoxy Coating

Nohyu Kim,Hwan-Seon Nah 한국비파괴검사학회 2014 한국비파괴검사학회지 Vol.34 No.2

An epoxy coating applied to the concrete surface of a containment building deteriorates in hazardous environments such as those containing radiation, heat, and moisture. Unlike metals, the epoxy coating on a concrete liner absorbs and discharges moisture during the degradations process, so it has a different density and volume during service. In this study, acoustic impedance was adopted for characterizing the degradation of a glass-reinforced epoxy coating using the acoustic reflection coefficient (reflectance) on a rough epoxy coating. For estimating the acoustic reflectance on a wavy epoxy coating surface, a probabilistic model was developed to represent the multiple irregular reflections of the acoustic wave from the wavy surface on the basis of the simulated annealing technique. A number of epoxy-coated concrete specimens were prepared and exposed to accelerated aging conditions to induce an artificial aging degradation in them. The acoustic impedance of the degraded epoxy coating was estimated successfully by minimizing the error between a waveform calculated from the mathematical model and a waveform measured from the surface of the rough coating.

Stochastic Estimation of Acoustic Impedance of Glass-Reinforced Epoxy Coating

김노유,나환선 한국비파괴검사학회 2014 한국비파괴검사학회지 Vol.34 No.2

An epoxy coating applied to the concrete surface of a containment building deteriorates in hazardous environments such as those containing radiation, heat, and moisture. Unlike metals, the epoxy coating on a concrete liner absorbs and discharges moisture during the degradations process, so it has a different density and volume during service. In this study, acoustic impedance was adopted for characterizing the degradation of a glass-reinforced epoxy coating using the acoustic reflection coefficient (reflectance) on a rough epoxy coating. For estimating the acoustic reflectance on a wavy epoxy coating surface, a probabilistic model was developed to represent the multiple irregular reflections of the acoustic wave from the wavy surface on the basis of the simulated annealing technique. A number of epoxy-coated concrete specimens were prepared and exposed to accelerated aging conditions to induce an artificial aging degradation in them. The acoustic impedance of the degraded epoxy coating was estimated successfully by minimizing the error between a waveform calculated from the mathematical model and a waveform measured from the surface of the rough coating.

부착력과 임피던스를 이용한 에폭시 도장재 열화 특성에 관한 실험적 평가

나환선 ( Nah Hwan-seon ),김노유 ( Kim Noh-yu ),권기주 ( Kwon Ki-joo ),송영철 ( Song Young-chol ) 한국구조물진단유지관리공학회 2003 한국구조물진단유지관리공학회 논문집 Vol.7 No.2

The purpose of this paper is to quantitatively investigate aging state of epoxy coating on containment structure at nuclear power plant. In order to evaluate an physical bonding of the epoxy coating, adhesion test was performed on a degraded epoxy coating on concrete specimens fabricated by accelerated aging experiment. In addition, impedance data by ultrasonic test were measured to compare with adhesion data. From almost 50 % of the specimens, aging phenomena of epoxy coating such as pin hole, blistering was discovered. To improve reliability on quality degradation of epoxy, co-relation between two kinds of different data was analyzed. By tracing co-related these data, it was possible to figure out physical state of as-built epoxy coating. The possibility to develop new methodology of time - dependent aging state on epoxy coating was found and discussed.

Influence of different fatigue loads and coating thicknesses on service performance of RC beam specimens with epoxy-coated reinforcement

Xiao-Hui Wang,Yang Gao,Run-Dong Gao,Jing Wang,Xi-La Liu 사단법인 한국계산역학회 2017 Computers and Concrete, An International Journal Vol.19 No.3

Epoxy-coated reinforcing bars are widely used to protect the corrosion of the reinforcing bars in the RC elements under their in-service environments and external loads. In most field surveys, it was reported that the corrosion resistance of the epoxy-coated reinforcing bars is typically better than the uncoated bars. However, from the experimental tests conducted in the labs, it was reported that, under the same loads, the RC elements with epoxy-coated reinforcing bars had wider cracks than the elements reinforced with the ordinary bars. Although this conclusion may be true considering the bond reduction of the reinforcing bar due to the epoxy coating, the maximum service loads used in the experimental research may be a main reason. To answer these two phenomena, service performance of 15 RC beam specimens with uncoated and epoxy-coated reinforcements under different fatigue loads was experimentally studied. Influences of different coating thicknesses of the reinforcing bars, the fatigue load range and load upper limit as well as fatigue load cycles on the mechanical performance of RC test specimens are discussed. It is concluded that, for the test specimens subjected to the comparatively lower load range and load upper limit, adverse effect on the service performance of test specimens with thicker epoxy-coated reinforcing bars is negligible. With the increments of the coating thickness and the in-service loading level, i.e., fatigue load range, load upper limit and fatigue cycles, the adverse factor resulting from the thicker coating becomes noticeable.

Stochastic Estimation of Acoustic Impedance of Glass-Reinforced Epoxy Coating

Kim, Nohyu,Nah, Hwan-Seon The Korean Society for Nondestructive Testing 2014 한국비파괴검사학회지 Vol.34 No.2

An epoxy coating applied to the concrete surface of a containment building deteriorates in hazardous environments such as those containing radiation, heat, and moisture. Unlike metals, the epoxy coating on a concrete liner absorbs and discharges moisture during the degradations process, so it has a different density and volume during service. In this study, acoustic impedance was adopted for characterizing the degradation of a glass-reinforced epoxy coating using the acoustic reflection coefficient (reflectance) on a rough epoxy coating. For estimating the acoustic reflectance on a wavy epoxy coating surface, a probabilistic model was developed to represent the multiple irregular reflections of the acoustic wave from the wavy surface on the basis of the simulated annealing technique. A number of epoxy-coated concrete specimens were prepared and exposed to accelerated aging conditions to induce an artificial aging degradation in them. The acoustic impedance of the degraded epoxy coating was estimated successfully by minimizing the error between a waveform calculated from the mathematical model and a waveform measured from the surface of the rough coating.

Study on Hygrothermal Degradation and Corrosion Protection of Epoxy Coatings Cured by Different Amine Based Curing Agents

( Min Young Shon ),( Huck Sang Kwon ) 한국부식방식학회 2010 Corrosion Science and Technology Vol.9 No.5

Epoxy coatings cured by different amine based curing agents have been prepared. Atomic force microscopy (AFM) has been used to monitor the surface topology changes of epoxy coatings before and after hygrothermal cyclic test. The glass transition temperature (Tg) and coefficient of thermal expansion (CTE) of the epoxy coating were measured by Thermo-mechanical Analysis (TMA). The Electrochemical impedance spectroscopy (EIS) with hygrothermal cyclic test ha been introduced to evaluate the corrosion protection of the epoxy coating. In conclusion, thermal properties of epoxy coatings were in good agreement with the results of corrosion protection of epoxy coated carbon steel obtained result by EIS with hygrothermal cyclic test. The relationship between thermal propc11ies, surface roughness changes and corrosion protection of epoxy coatings are discussed in this study.

Effect of Solution Temperature on the Cavitation Degradation Properties of Epoxy Coatings for Seawater Piping

( J. M. Jeon ),( Y. R. Yoo ),( M. J. Jeong ),( Y. C. Kim ),( Y. S. Kim ) 한국부식방식학회 2021 Corrosion Science and Technology Vol.20 No.6

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.

Preparation and Performance Study of Nano-Ti-MWCNT Hybrid Filler Reinforced Epoxy Resin Composite Coating

Hui Chai,Waheed Ur Rehman,Xuyun Yang,Tao Meng,Renyang He 한국섬유공학회 2022 Fibers and polymers Vol.23 No.10

To improve the wear resistance of friction components coated with epoxy resin, a titanium-multi-walled carbonnanotubes (Ti-MWCNT) reinforced epoxy resin composite coating was designed and prepared by combining metalnanoparticles and inorganic nanoparticles into a hybrid filler using Ti nanoparticles and MWCNT as raw materials. Thechanges in functional groups of pure resin and Ti-MWCNT reinforced epoxy resin composites were analyzed using infraredspectroscopy. The hardness, fracture toughness and tribological properties of pure resin and Ti-MWCNT-reinforced epoxyresin composite coatings with different contents of Ti-MWCNT filler (0, 2 wt.%, 4 wt.%, 6 wt.%, 8 wt.%) were determinedexperimentally. The fracture and wear mechanisms of Ti-MWCNT-reinforced epoxy resin composites were also revealedwith the aid of scanning electron microscopy. The results showed that the bonding form of Ti-MWCNT hybrid filler andepoxy resin was physical bonding. The addition of appropriate amount of Ti-MWCNT hybrid filler effectively improved thehardness, fracture toughness and tribological properties of epoxy resin. When 6 wt.% Ti-MWCNT hybrid filler was added,the optimum composite was obtained with hardness and fracture toughness of 676 HL and 0.922 MPa·m1/2, and frictioncoefficient and wear rate of 0.347 and 4.71×10-13 m3(N·m)-1, respectively. However, the performance of the compositecoating gradually decreased when the filler content was increased to 8 wt.%. In summary, the addition of appropriate amountof Ti-MWCNT hybrid filler can effectively improve the hardness, fracture toughness and tribological properties of epoxyresin. Ti nanoparticles react chemically with oxygen and effectively fill the microcracks generated in the resin matrix. TheMWCNT filler limits the movement of the surrounding resin matrix due to the difference in size and prolongs the diffusionpath of the microcracks in the resin matrix. The interaction between the two filler components significantly improves theperformance of the composite coating.

Anti-corrosive performance of epoxy coatings containing various nano-particles for splash zone applications

Mohammad Asif Alam,Ubair Abdus Samad,Rawaiz Khan,Manawwer Alam,Saeed Mohammed Al-Zahrani 한국화학공학회 2017 Korean Journal of Chemical Engineering Vol.34 No.8

Various formulations of epoxy nano-composites coating were developed by incorporating the nanoparticles (NPs) of ZnO, ZrO2, and SiO2 (2 wt%) in commercially available epoxy resin as the matrix phase. Direct incorporation method was used for the addition of NPs in epoxy matrix. High-speed mechanical stirring and ultra-sonication were carried out to facilitate the dispersion of NPs in the presence of acetone used as a solvent. Coating of neat epoxy and NPs (ZnO, ZrO2, SiO2) doped coating was applied on mild steel substrate for corrosion analysis. The effect of the incorporation of various NPs on anti-corrosive properties of the epoxy/nano-composite coatings was investigated by electrochemical impedance spectroscopy technique. The experimental results showed an improvement in the anticorrosive properties for EZr coatings as compared with pristine and other nanocomposite coating samples.

GIS내 금속이물 존재시 에폭시 절연코팅의 효과

곽희로,구교선,김영찬 한국조명전기설비학회 2003 조명·전기설비학회논문지 Vol.17 No.2

본 논문에서는 모의 GIS를 에폭시로 코팅하고, 금속이물 혼입시의 부분방전, 부상전압, 절연파괴전압 등을 측정하여, 코팅하지 알았을 경우와 비교 분석하였다. 또한, 여러 경우의 절연사고를 모의하기 위해, SF$_{6}$/$N_2$가스 혼합비, 금속이물의 재질, 직경, 코팅두께, 압력 등을 변화시키면서 전기적특성을 관찰하였다. 실험결과, 코팅두께가 증가할수록 부분방전개시전압이 증가하였으며, 부분방전의 크기는 감소하였다. 또한 철합금 파티클의 부상전압이 구리파티클보다 높았으며, 직경이 증가할수록 부상전압도 증가하였으며, 코팅두께가 두꺼워질수록 절연파괴 전압이 증가하였다. 이상의 연구결과 GIS를 에폭시로 코팅함으로써 절연성능을 향상시킬 수 있음을 확인하였다. In this paper, partial discharges(PDs), lift off and breakdown voltage were measured when metal particles existed in a model GIS coated with epoxy resin on its bottom electrode, and the measured results were analyzed after comparing with the model DIS not coated. In order to presume the various fault case in GIS, we measured the experimental values with changing some experimental factors, such as the mixture ratio of SF$\_$6//N$_2$, the pressure of the gases, the kinds and diameter of the metal particles, and the coating thickness of the epoxy resin. As a result, the PDIV increased with the thickness of the epoxy resin, while the magnitude of PDs decreased at the same condition. The lift off voltages of steel alloy particles were higher than that of copper particles, and increased wit diameter of particles. Futhermore, the lift off voltages in the case of the electrode coated with epoxy resin were higher than that in the case of the uncoated one. In addition, the thicker the thickness of the epoxy resin was, the higher the breakdown voltage were. Thus, it was confirmed that the GIS coated with epoxy resin on its inner surface could be improved in insulation performance.