한국부식방식학회

Page : 68 - 76 DOWNLOAD
Al-Zn-Zr 용사코팅층의 고체입자 충돌 침식특성에 미치는 봉공처리의 영향
Several technologies are employed to protect substrates from corrosion and erosion damage. In particular, arc thermal spray coating technology is widely used as anti-corrosive technology for steel and concrete structures and is applied to offshore plants and petrochemical and drilling facilities. In this investigation, solid particle impingement erosion experiments were performed on an arc thermal spraying-coated specimen using 85% Al–14% Zn–1% Zr wire rod in KR-RA steel. This study investigated the effect of fluorosilicone sealing on the erosion resistance characteristics of the thermal spray coating layer. The erosion rates of the thermal spray-coated and sealed specimens were 4.1×10-4 and 8.5×10-4, respectively. At the beginning of the experiment, the fluorosilicone sealant was almost destroyed by the impact of the solid particles. The destruction time for the coating layer was 10 minutes for the thermal spray-coated specimen and 13 minutes for the sealed specimens, indicating that the sealed specimens had better erosion resistance characteristics to solid particle impingement.
KEYWORDs : Thermal spraying, Solid particle impingement, Erosion, Fluorosilicone, Sealing
AUTHORs : 허호성 · 김성종†

Page : 62 - 67 DOWNLOAD
지역난방 증기 터빈 내 조속기 밸브 Inlet pipe 파손 원인 분석
The objective of this study was to perform failure analysis of an inlet pipe located in a governor valve of a steam turbine in a district heating system. During the operation, the temperature of the governor valve was increased to as high as ~500 oC, which induced thermal expansion of the inlet pipe along both axial and radial directions. While the inlet pipe did not have contact with the valve seat, the side plane of the upside was constrained by the casing part, which led the inlet pipe to experience stress field in the form of fatigue and creep. The primary crack was initiated at about 30 mm below the top where the complex stress field was anticipated. These results suggest that the main failure mechanism is a combination of thermal fatigue and creep during the operation supported by the observation of apparent beach marks on the fracture surface and pores near the cracks, respectively.
KEYWORDs : District heating, Steam turbine, Inlet pipe, Thermal fatigue, Creep
AUTHORs : 채호병 · 김우철 · 김희산 · 김정구 · 이수열†

Page : 53 - 61 DOWNLOAD
Oxidation of Fe-(5.3-29.8)%Mn-(1.1-1.9)%Al-0.45%C Alloys at 550-650 oC
Alloys of Fe-(5.3-29.8)%Mn-(1.1-1.9)%Al-(0.4-0.5)%C were oxidized at 550 oC to 650 oC for 20 h to understand effects of alloying elements on oxidation. Their oxidation resistance increased with increasing Mn level to a small extent. Their oxidation kinetics changed from parabolic to linear when Mn content was decreased and temperature was increasing. Oxide scales primarily consisted of Fe2O3, Mn2O3, and MnFe2O4 without any protective Al-bearing oxides. During oxidation, Fe, Mn, and a lesser amount of Al diffused outward, while oxygen diffused inward to form internal oxides. Both oxide scales and internal oxides consisted of Fe, Mn, and a small amount of Al. The oxidation of Mn and carbon transformed γ-matrix to α-matrix in the subscale. The oxidation led to the formation of relatively thick oxide scales due to inherently inferior oxidation resistance of alloys and the formation of voids and cracks due to evaporation of manganese, decarburization, and outward diffusion of cations across oxides.
KEYWORDs : High-Mn steel, Oxidation, Oxide scale, Iron, Manganese
AUTHORs : Soon Yong Park, Xiao Xiao, Min Ji Kim, Geun Taek Lee, Dae Ho Hwang, Young Ho Woo, and Dong Bok Lee†

Page : 41 - 52 DOWNLOAD
Evaluation of Corrosion Resistance Properties of Hexagonal Boron Nitride Based Polymer Composite Coatings for Carbon Steel in a Saline Environment
Herein, we report polyvinyl butyral composites coatings containing various loadings of 72-h bath sonicated hexagonal boron nitride particles (5 μm) to enhance barrier properties of coatings. Barrier properties of coatings were determined in 3.5 wt% NaCl after different time periods of immersion via electrochemical techniques such as open circuit potential, electrochemical impedance spectroscopy, and potentiodynamic polarization test. Coatings containing sonicated hexagonal boron particles exhibited improved corrosion resistance for longer periods of immersion compared to neat coating. We also discussed effects of hexagonal boron nitride on healing properties of polyvinyl butyral. Coatings containing 1.0 wt% loading of sonicated hexagonal boron nitride showed improved long-term barrier properties than coatings with other compositions. The presence of hexagonal boron nitride also affected the healing properties of polyvinyl butyral coatings besides their barrier properties. Such improved barrier properties of composites coatings were attributed to the high aspect ratio, plate-like shape, and electrically insulated nature of the filler.
KEYWORDs : Coating, h-BN, EIS, OCP, Carbon steel, Polymer
AUTHORs : Fadhel T. Alabdullah†, C. Ali, and Brajendra Mishra

Page : 32 - 40 DOWNLOAD
Corrosion Inhibition Studies on Low Carbon Steel in Hydrochloric Acid Medium Using o-Vanillin-Glutamine Schiff Base
The o-Vanillin - Glutamine Schiff base [2-Hydroxy-3-Methoxy BenzylidineCarbomyl) -2-Butanoic Acid] was examined for low carbon steel corrosion inhibition in acid media. Weight loss studies were carried out at three different temperatures to determine the inhibition efficiency (IE). Electrochemical impedance spectroscopy revealed that the charge transfer resistance controlled the corrosion reaction and Tafel polarization indicated that the Schiff base acts as mixed mode of inhibitor. SEM images were recorded for the surface morphology of the low carbon steel surface. DFT studies revealed corrosion control mechanisms using quantum chemical parameters such as EHOMO, ELUMO, energy gap (ΔΕ), chemical Hardness (η), chemical Softness (σ), Electronegativity (χ), and the fraction of electron transferred (ΔN) , which is calculated using Gaussian software 09. The gas-phase geometry was fully optimized in the Density Functional Theory (DFT/B3LYP-6-31G (d)).The DFT results are in good agreement with the experimental results. All the results proved that the Schiff Base (2-Hydroxy-3-Metoxy BenzylidineCarbomyl) -2-Butanoic is a suitable alternative for corrosion inhibition of low carbon steel in acid media.
KEYWORDs : DFT, Electrochemical studies, Schiff base, SEM, Weight loss
AUTHORs : G. Rexin Thusnavis†, T. V. Archana, P. Palanisamy

Page : 21 - 31 DOWNLOAD
Nystatin Drug as an Effective Corrosion Inhibitor for Mild Steel in Acidic Media– An Experimental and Theoretical Study
Potentiodynamic polarization, EIS measurements, quantum chemical calculations, and molecular dynamic simulations were used to investigate the corrosion behavior of mild steel in 0.5 M aqueous hydrochloric acid medium in the presence or absence of nystatin drug. Potentiodynamic tests suggested that this molecule could act as a mixed inhibitor due to its adsorption on the mild steel surface. The objective of this study was to exploit theoretical calculations to gain a better understanding mechanism of inhibition. Calculating the adsorption behavior of the investigated molecule on Fe (1 1 0) surface was accomplished using Monte Carlo simulation. Molecules were also investigated using Density Functional Theory (DFT), specifically PBE functional, in order to identify the link between molecular structure and corrosion inhibition behavior of the compound under investigation. Adsorption energies between nystatin and iron were estimated more accurately by utilizing Molecular Mechanics calculation with Periodic Boundary Conditions (PBC). Estimated theoretical parameters significantly assisted our understanding of the corrosion inhibition mechanism exhibited by this molecule. They were found to be in accord with experimental results.
KEYWORDs : Corrosion inhibition, Nystatin, Tafel plots, DFT, MC and MD
AUTHORs : Valbonë Mehmeti†

Page : 9 - 20 DOWNLOAD
Use of Capparis decidua Extract as a Green Inhibitor for Pure Aluminum Corrosion in Acidic Media
The aim of this paper is to study corrosion inhibition of Aluminum with Capparis decidua extract. The study was performed in a 1.0 M solution of hydrochloric acid (HCl) and was monitored both by measuring mass loss and by using electrochemical and polarization methods. A scanning electron microscopy (SEM) technique was also applied for surface morphology analysis. The results revealed high inhibition efficiency of Capparis decidua extract. Our data also determined that efficiency is governed by temperature and concentration of extract. Optimum (88.2%) inhibitor efficiency was found with maximum extract concentration at 45 oC. The results also showed a slight diminution of aluminum dissolution when the temperature is low. Based on the Langmuir adsorption model, Capparis decidua adsorption on the aluminum surface shows a high regression coefficient value. From the results, the activation enthalpy (ΔH#) and activation entropy (ΔS#) were estimated and discussed. In conclusion, the study clearly shows that Capparis decidua extract acted against aluminum corrosion in acidic media by forming a protective film on top of the aluminum surface.
KEYWORDs : Aluminum corrosion, Aluminum corrosion inhibition, Corrosion inhibitor, Green corrosion inhibitor, Organic extract corrosion inhibitor
AUTHORs : Nezar Al-Bataineh†, Mahmoud A. Al-Qudah, Sultan Abu-Orabi, Tareq Bataineh, Rasha S. Hamaideh, Idrees F. Al-Momani, and Ahmed K. Hijazi

Page : 1 - 8 DOWNLOAD
A Study on the Application of Cathodic Protection for Anti-Corrosion of Automobile Body
The use of cathodic protection for metals can be achieved by sacrificial anode CP or impressed current CP, or a combination of both. Cathodic protection is a highly effective anti-corrosion technique for submerged metals or metals in soil. But because the non-immersion atmospheric automobile environment is a high resistance environment, it is limited by fundamental cathodic protection. However, the application of cathodic protection to automobiles is attractive because of the possibility of maintaining corrosion resistance while using lower-cost materials. A commercially available product for automobiles that uses both sacrificial anode CP and impressed current CP was tested in a periodic salt spray environment to investigate the performance of the devices. Experimental results show that the metal to be protected has different anti-corrosion effects depending on the distance from the anode of the device, but it is effective for the entire 120 cm long specimen exposed with one anode. The cathodic protection is effective because the conductive tape attached to the anode of the structure to be protected acts as a constant electrolyte in wet and dry conditions. The results show that the entire standard passenger car can be protected by cathodic protection with 4 anodes.
KEYWORDs : Cathodic protection for automobiles, Cathodic protection devices, Electronic rust prevention
AUTHORs : DaeHong Sohn†, Yongho lee, HeeJin Jang, and SooYeon Cho

메인메뉴

메뉴

하단메뉴