Search results for: corrosion behavior

Authors: Fuyan Sun, Guang Wang, Xueyuan Nie

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In this study, a plasma electrolytic oxidation (PEO) process was used to form titanium-aluminium oxide coating on aluminized steel. The present work was mainly to study the effects of treatment time of PEO process on properties of the titanium coating. A potentiodynamic polarization corrosion test was employed to investigate the corrosion resistance of the coating. The friction coefficient and wear resistance of the coating were studied by using pin-on-disc test. The thermal transfer behaviours of uncoated and PEO-coated aluminized steels were also studied. It could be seen that treatment time of PEO process significantly influenced the properties of the titanium oxide coating. Samples with a longer treatment time had a better performance for corrosion and wear protection. This paper demonstrated different treatment time could alter the surface behaviour of the coating material.

Keywords: titanium-aluminum oxide, plasma electrolytic oxidation, corrosion, wear, thermal property

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Authors: K. S. Ghosh, Sagnik Bose, Kapil Tripati

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Potentiodynamic polarization studies carried out on AA2024 and AA2014 Al-Cu-Mg alloys of various tempers in 3.5 wt. % NaCl and in 3.5 wt. % NaCl + 1.0 % H2O2 solution characteristic E-i curves. Corrosion potential (Ecorr) value has shifted towards more negative potential with the increase of artificial aging time. The Ecorr value for the alloy tempers has also shifted anodically in presence of H2O2 in 3.5 % NaCl solution. Further, passivity phenomenon has been observed in all the alloy tempers when tested in 3.5 wt. % NaCl solution at pH 12. Stress corrosion cracking (SCC) behaviour of friction stir weld (FSW) joint of AA2014 alloy has been studied bu slow strain rate test (SSRT) in 3.5 wt. % NaCl solution. Optical micrographs of the corroded surfaces of polarised samples showed general corrosion, extensive pitting and intergranular corrosion as well. Further, potentiodynamic cyclic polarization curves displayed wide hysteresis loop indicating that the alloy tempers are susceptible to pit growth damage. Attempts have been made to explain the variation of observed electrochemical and SCC behaviour of the alloy tempers and the electrolyte conditions with the help of microstructural features.

Keywords: AA 2014 and AA 2024 Al-C-Mg alloy, artificial ageing, potentiodynamic polarization, TEM micrographs, stress corrosion cracking (SCC)

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Authors: Hasan Izhar Khan, Naiqiang Zhang, Hong Xu, Zhongliang Zhu, Dongfang Jiang

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Inconel 617, a nickel-based alloy designed for high-temperature applications, got an excellent amalgamation of strength and oxidation resistance at high temperatures. For a better understanding of its suitability to be used in superheater and reheater tubes in ultra-supercritical power plants, stress corrosion cracking (SCC) susceptibility must be evaluated. In the present study, the effect of medium environment on SCC behavior of Inconel 617, in the form of a round bar tensile specimen, was tested via slow strain rate tensile tests in steam and supercritical water (SCW) at 650 °C. The results showed that SCC susceptibility has a linear relationship with exposed pressure and increases monotonically with an increase in pressure. A severe SCC susceptibility was observed in SCW followed by that in a steam environment. Fracture and gage surface showed apparent characteristics of brittle fracture. Intergranular cracks initiated from the edge region and propagated into the matrix through cross section until ductile rupture. When dissolved oxygen contents were decreased in SCW environment, it showed no noticeable effect on mechanical properties but SCC susceptibility slightly decreased. The research revealed the influence of environment on SCC susceptibility of Inconel 617 in steam and SCW.

Keywords: Inconel 617, steam, supercritical water, stress corrosion cracking

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Authors: S. Tunmee, P. Wongpanya, I. Toda, X. L. Zhou, Y. Nakaya, N. Konkhunthot, S. Arakawa, H. Saitoh

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The hydrogenated amorphous carbon films (a-C:H) were deposited on p-type Si (100) substrates at different thicknesses by radio frequency plasma enhanced chemical vapor deposition technique (rf-PECVD). Raman spectra display asymmetric diamond-like peaks, representative of the a-C:H films. The decrease of intensity ID/IG ratios revealed the sp3 content arise at different thicknesses of the a-C:H films. In terms of mechanical properties, the high hardness and elastic modulus values show the elastic and plastic deformation behaviors related to sp3 content in amorphous carbon films. Electro chemical properties showed that the a-C:H films exhibited excellent corrosion resistance in air-saturated 3.5 wt% NaCl solution for pH 2 at room temperature. Thickness increasing affected the small sp2 clusters in matrix, restricting the velocity transfer and exchange of electrons. The deposited a-C:H films exhibited excellent mechanical properties and corrosion resistance.

Keywords: thickness, mechanical properties, electrochemical corrosion properties, a-C:H film

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Authors: Chun-Qing Li, Guoyang Fu, Wei Yang

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A significant portion of current water networks is made of cast iron pipes. Due to aging and deterioration with corrosion being the most predominant mechanism, the failure rate of cast iron pipes is very high. Although considerable research has been carried out in the past few decades, most are on the effect of corrosion on the structural capacity of pipes using strength theory as the failure criterion. This paper presents a reliability-based methodology for the assessment of corrosion affected cast iron pipe cracking failures. A nonlinear limit state function taking into account all three fracture modes is proposed for brittle metal pipes with mixed mode fracture. A stochastic model of the load effect is developed, and time-dependent reliability method is employed to quantify the probability of failure and predict the remaining service life. A case study is carried out using the proposed methodology, followed by sensitivity analysis to investigate the effects of the random variables on the probability of failure. It has been found that the larger the inclination angle or the Mode I fracture toughness is, the smaller the probability of pipe failure is. It has also been found that the multiplying and exponential coefficients k and n in the power law corrosion model and the internal pressure have the most influence on the probability of failure for cast iron pipes. The methodology presented in this paper can assist pipe engineers and asset managers in developing a risk-informed and cost-effective strategy for better management of corrosion-affected pipelines.

Keywords: corrosion, inclined surface cracks, pressurized cast iron pipes, stress intensity

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Authors: O. Çomaklı, M. Yazıcı, T. Yetim, A. F. Yetim, A. Çelik

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In this work, TiO₂ films were deposited on Cp-Ti substrates by thermal oxidation, DC plasma oxidation, and by the sol-gel method. Microstructures of uncoated and TiO₂ film coated samples were examined by X-ray diffraction and SEM. Thin oxide film consisting of anatase (A) and rutile (R) TiO₂ structures was observed on the surface of CP-Ti by under three different treatments. Also, the more intense anatase and rutile peaks appeared at samples plasma oxidized at 700˚C. The thicknesses of films were about 1.8 μm at the TiO₂ film coated samples by sol-gel and about 2.7 μm at thermal oxidated samples, while it was measured as 3.9 μm at the plasma oxidated samples. Electrochemical corrosion behaviour of uncoated and coated specimens was mainly carried out by potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) in simulated body fluid (SBF) solution. Results showed that at the plasma oxidated samples exhibited a better resistance property to corrosion than that of other treatments.

Keywords: TiO₂, CP-Ti, corrosion properties, thermal oxidation, plasma oxidation, sol-gel

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Authors: Taher S. Ababneh, Taghreed M. A. Jazzazi, Tareq M. A. Alshboul

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The inhibiting action against aluminum corrosion by three derivatives of 1,8-bis (benzylideneamino) naphthalene (BN) Schiff base has been investigated by means of DFT quantum chemical calculations at the B3LYP/6-31G(d) level of theory. The derivatives (CBN, NBN and MBN) were prepared from the condensation reaction of 1,8-diaminonaphthalene with substituted benzaldehyde (4-CN, 3-NO₂ and 3,4-(OMe)₂, respectively). Calculations were conducted to study the adsorption of each Schiff base on aluminum surface to evaluate its potential as a corrosion inhibitor. The computational structural features and electronic properties of each derivative such as relative energies and energies of the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) have been reported. Thermodynamic functions and quantum chemical parameters such as the hardness of the inhibitor, the softness and the electrophilicity index were calculated to determine the derivative of the highest inhibition efficiency.

Keywords: corrosion, aluminum, DFT calculation, 1, 8-diaminonaphthalene, benzaldehyde

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Authors: Mohammad R. Irshidat, Rami H. Haddad, Hanadi Al-Mahmoud

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Reinforced concrete (RC) is the most common used material for construction in the world. In the past decades, fiber reinforced polymer (FRP) bars had been widely used to substitute the steel bars due to their high resistance to corrosion, high tensile capacity, and low weight in comparison with steel. Experimental studies on the behavior of FRP bar reinforced concrete beams had been carried out worldwide for a few decades. While the research on such structural members under elevated temperatures is still very limited. In this research, the flexural behavior of heat-damaged concrete beams reinforced with FRP bars is studied. Two types of FRP rebar namely, carbon fiber reinforced polymer (CFRP) and glass fiber reinforced polymer (GFRP), are used. The beams are subjected to four levels of temperature before tested to monitor their flexural behavior. The results are compared with other concrete beams reinforced with regular steel bars. The results show that the beams reinforced with CFRP bars and GFRP bars had higher flexural capacity than the beams reinforced with steel bars even if heated up to 400°C and 300°C, respectively. After that the beams reinforced with steel bars had the superiority.

Keywords: concrete beams, FRP rebar, flexural behavior, heat-damaged

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Authors: Asiful Hossain Seikh, Mohammad Asif Alam, Ubair Abdus Samad, Jabair A. Mohammed, S. M. Al-Zahrani, El-Sayed M. Sherif

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In this current investigation, aliphatic amine-cured diglycidyl ether of bisphenol-A (DGEBA) based epoxy coating was mixed with certain weight % hardener polyaminoamide (1:2) and was coated on carbon steel panels with and without 1% nano crystalline Al powder. The corrosion behavior of the coated samples were investigated by exposing them in the salt spray chamber, for 500 hours. According to ASTM-B-117, the bath was kept at 35 °C and 5% NaCl containing mist was sprayed at 1.3 bars pressure. Composition of coatings was confirmed using Fourier-transform infrared spectroscopy (FTIR). Electrochemical characterization of the coated samples was also performed using potentiodynamic polarization technique and electrochemical impedance spectroscopy (EIS) technique. All the experiments were done in 3.5% NaCl solution. The nano Al coated sample shows good corrosion resistance property compared to bare Al sample. In fact after salt spray exposure no pitting or local damage was observed for nano coated sample and the coating gloss was negligibly affected. The surface morphology of coated and corroded samples was studied using scanning electron microscopy (SEM).

Keywords: epoxy, nano aluminium, potentiodynamic polarization, salt spray, electrochemical impedence spectroscopy

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Authors: Sami I. Jafar, Sami A. Ajeel, Zaman A. Abdulwahab

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The turbine blades used in electric power plants are made of low alloy steel type 52. These blades will be subjected to fatigue and also at other times to fatigue corrosion with aging time. Due to their continuous exposure to cyclic rotational stresses in corrosive steam environments, The current research aims to deal with this problem using the laser cladding method for low alloy steel type 52, which works to re-compose the metallurgical structure and improve the mechanical properties by strengthening the resulting structure, which leads to an increase in fatigue and wears resistance, therefore, an increase in the life of these blades is observed.

Keywords: fatigue, fatigue corrosion, turbine blades, laser cladding

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Authors: Melby Chacko, Jagannath Nayak

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6061 Al-SiCp composite was solutionized at 350 °C for 30 minutes and water quenched. It was then underaged at 140 °C (T6 treatment). The aging behaviour of the composite was studied using Rockwell B hardness measurement. Corrosion behaviour of the underaged sample was studied in different concentrations of acetic acid and at different temperatures. Benzimidazole at different concentrations was used for the inhibition studies. Inhibition efficiency of benzimidazole was calculated for different experimental conditions. Thermodynamic parameters were found out which suggested benzimidazole is an efficient inhibitor and it adsorbed onto the surface of composite by mixed adsorption where chemisorption is predominant.

Keywords: 6061 Al-SiCp composite, T6 treatment, corrosion inhibition, chemisorption

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Authors: Mandlenkosi G. R. Mahlobo, Peter A. Olubambi, Philippe Refait

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The aim of this study was to use voltammetry as a method to understand the behaviour of steel in unsaturated soil in the presence of cathodic protection (CP). Three carbon steel coupons were buried in artificial soil wetted at 65-70% of saturation for 37 days. All three coupons were left at open circuit potential (OCP) for the first seven days in the unsaturated soil before CP, which was only applied on two of the three coupons at the protection potential -0.8 V vs Cu/CuSO₄ for the remaining 30 days of the experiment. Voltammetry was performed weekly on the coupon without CP, while electrochemical impedance spectroscopy (EIS) was performed daily to monitor and correct the applied CP potential from the ohmic drop. Voltammetry was finally performed on the last day on the coupons under CP. All the voltammograms were modeled with mathematical equations in order to compute the electrochemical parameters and subsequently deduced the corrosion rate of the steel coupons. For the coupon without CP, the corrosion rate was determined at 300 µm/y. For the coupons under CP, the residual corrosion rate under CP was estimated at 12 µm/y while the corrosion rate of the coupons, after interruption of CP, was estimated at 25 µm/y. This showed that CP was efficient due to two effects: a direct effect from the decreased potential and an induced effect associated with the increased interfacial pH that promoted the formation of a protective layer on the steel surface.

Keywords: carbon steel, cathodic protection, voltammetry, unsaturated soil, Raman spectroscopy

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Authors: V. E. Bazhenov, A. V. Li, A. A. Komissarov, A. V. Koltygin, S. A. Tavolzhanskii, O. O. Voropaeva, A. M. Mukhametshina, A. A. Tokar, V. A. Bautin

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Magnesium-based alloys are considered as effective materials in the development of biodegradable implants. The magnesium alloys containing Mg, Zn, Ca as an alloying element are the subject of the particular interest. These elements are the nutrients for the human body, which provide their high biocompatibility. In this work, we investigated the effect of severe plastic deformation (SPD) on the mechanical and corrosion properties of Mg-Zn-Ca and Mg-Zn-Ca-Mn alloys containing from 2 to 4 wt.% Zn; 0.7 wt.% Ca and up to 1 wt.% Mn. Hot extrusion was used as a method of intensive plastic deformation. The temperature of hot extrusion was set to 220 °C and 300 °C. Metallographic analysis after hot extrusion shows that the grain size in the studied alloys depends on the deformation temperature. The grain size for all of investigated alloys is in the range from 3 to 7 microns, and 3 μm corresponds to the extrusion temperature of 220 °C. Analysis of mechanical properties after extrusion shows that extrusion at a temperature of 220 °C and alloying with Mn increase the strength characteristics and decrease the ductility of studied alloys. A slight anisotropy of properties in the longitudinal and transverse directions was also observed. Measurements of corrosion properties revealed that the addition of Mn to Mg-Zn-Ca alloys reduces the corrosion rate. On the other hand, increasing the Zn content in alloys increases the corrosion rate. The extrusion temperature practically does not affect the corrosion rate. Acknowledgement: The authors gratefully acknowledge the financial support of the Ministry of Science and Higher Education of the Russian Federation in the framework of Increase Competitiveness Program of NUST «MISiS» (No K2-2019-008), implemented by a governmental decree dated 16th of March 2013, N 211.

Keywords: biocompatibility, hot extrusion, magnesium alloys, severe plastic deformation, properties

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Authors: S. Taghavi Kalajahi, A. Koerdt, T. Lund Skovhus

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Cathodic protection (CP) is an electrochemical method to control and manage corrosion in different industries and environments. CP which is widely used, especially in buried and sub-merged environments, which both environments are susceptible to microbiologically influenced corrosion (MIC). Most of the standards recommend performing CP using -800 mV, however, if MIC threats are high or sulfate reducing bacteria (SRB) is present, the recommendation is to use more negative potentials for adequate protection of the metal. Due to the lack of knowledge and research on the effectiveness of CP on MIC, to the author’s best knowledge, there is no information about what MIC threat is and how much more negative potentials should be used enabling adequate protection and not overprotection (due to hydrogen embrittlement risk). Recently, the development and cheaper price of molecular microbial methods (MMMs) open the door for more effective investigations on the corrosion in the presence of microorganisms, along with other electrochemical methods and surface analysis. In this work, using MMMs, the gene expression of SRB biofilm under different potentials of CP will be investigated. The specific genes, such as pH buffering, metal oxidizing, etc., will be compared at different potentials, enabling to determine the precise potential that protect the metal effectively from SRB. This work is the initial step to be able to standardize the recommended potential under MIC condition, resulting better protection for the infrastructures.

Keywords: cathodic protection, microbiologically influenced corrosion, molecular microbial methods, sulfate reducing bacteria

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Authors: Zbigniew Szklarz, Aldona Garbacz-Klempka, Magdalena Bisztyga-Szklarz

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Typical metallic alloys bases on one major alloying component, where the addition of other elements is intended to improve or modify certain properties, most of all the mechanical properties. However, in 1995 a new concept of metallic alloys was described and defined. High Entropy Alloys (HEA) contains at least five alloying elements in an amount from 5 to 20 at.%. A common feature this type of alloys is an absence of intermetallic phases, high homogeneity of the microstructure and unique chemical composition, what leads to obtaining materials with very high strength indicators, stable structures (also at high temperatures) and excellent corrosion resistance. Hence, HEA can be successfully used as a substitutes for typical metallic alloys in various applications where a sufficiently high properties are desirable. For fabricating HEA, a few ways are applied: 1/ from liquid phase i.e. casting (usually arc melting); 2/ from solid phase i.e. powder metallurgy (sintering methods preceded by mechanical synthesis) and 3/ from gas phase e.g. sputtering or 4/ other deposition methods like electrodeposition from liquids. Application of different production methods creates different microstructures of HEA, which can entail differences in their properties. The last two methods also allows to obtain coatings with HEA structures, hereinafter referred to as High Entropy Films (HEF). With reference to above, the crucial aim of this work was the optimization of the manufacturing process of the multi-component metallic layers (HEF) by the low- and high temperature electrochemical deposition ( ED). The low-temperature deposition process was crried out at ambient or elevated temperature (up to 100 ᵒC) in organic electrolyte. The high-temperature electrodeposition (several hundred Celcius degrees), in turn, allowed to form the HEF layer by electrochemical reduction of metals from molten salts. The basic chemical composition of the coatings was CoCrFeMnNi (known as Cantor’s alloy). However, it was modified by other, selected elements like Al or Cu. The optimization of the parameters that allow to obtain as far as it possible homogeneous and equimolar composition of HEF is the main result of presented studies. In order to analyse and compare the microstructure, SEM/EBSD, TEM and XRD techniques were employed. Morover, the determination of corrosion resistance of the CoCrFeMnNi(Cu or Al) layers in selected electrolytes (i.e. organic and non-organic liquids) was no less important than the above mentioned objectives.

Keywords: high entropy alloys, electrodeposition, corrosion behavior, microstructure

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Authors: Mohamed A. Hegazy

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Most of Poly Vinyl Chloride (PVC) petrochemical companies produce huge amount of byproduct which characterized as carcinogenic liquid-wastes, insoluble in water, highly corrosive and highly offensive. This byproduct is partially use, a small part, in the production of hydrochloric acid and the huge part is a waste. Therefore, the aim of this work was to conversion of such PVC wastes, to an environmentally safe product that act as a corrosion Inhibitor for metals in ‎aqueous media and as a biocide for microorganisms. This conversion method was accomplished mainly to protect the environment and to produce high economic value-products. The conversion process was established and the final product was tested for the toxicity, water solubility in comparison to the crude product. Furthermore, the end product was tested as a corrosion inhibitor in 1M HCl and as a broad-spectrum biocide against standard microbial strains and against the environmentally isolated Sulfate-reducing bacteria (SRB) microbial community.

Keywords: PVC, surfactant, corrosion inhibitor, biocide, SRB

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Authors: Ahmed Chetouani

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Corrosion is a natural occurring process where it can be defined as the deterioration of materials properties due to its interaction with its environment. Corrosion can lead to failures in plant infrastructure and machines which are usually costly to repair. In terms of loss of contaminated products which will cause environmental damage and possibly costly in terms of human health. The driving force that causes metals to corrode is due to the natural consequence of their temporary existence in metallic form. There is a growing trend in utilizing plant extracts and pharmaceutical compounds as corrosion inhibitors. Exquisite identification of the essential oil of aerial parts of Pelargonium was obtained using hydrodistillation and identification using GC (gas chromatography) and GC/MS (gas chromatography-mass spectrometry). The oil was predominated by Citronellol (22.8%). The inhibitory effect of essential oil and extract of Pelargonium was estimated on the corrosion of mild steel in 1M hydrochloric acid (HCl) using weight loss, Electrochemical Impedance Spectroscopy (EIS) and Tafel polarization curves. Inhibition was found to increase with increasing concentration of the essential oil and extract of Pelargonium. The effect of temperature on the corrosion behaviour of mild steel in 1M HCl with addition of essential oil and extract was also studied and the thermodynamic parameters were determined and discussed. Values of inhibition efficiency were calculated from weight loss, Tafel polarization curves, and EIS. All results are in good agreement. Polarization curves showed that essential oil and extract of Pelargonium behave as mixed type inhibitors in hydrochloric acid. The results obtained showed that the essential oil and extract of Pelargonium could serve as an effective inhibitor of the corrosion of mild steel in Hydrochloric acid solution. To avoid any surprise of toxicity, the majority compounds have been studied by using POM analyses.

Keywords: corrosion inhibition, mild steel, pelargonium oil, extract, electrochemical system, hydrodistillation, side effects, POM Analyses

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Authors: Chahla Rahal, Philippe Refait

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Oleuropein-rich extract from olive leaf and acid hydrolysates, rich in hydroxytyrosol and elenolic acid was prepared under different experimental conditions. These phenolic compounds may be used as a corrosion inhibitor. The inhibitive action of these extracts and its major constituents on the corrosion of copper in 0.5 M NaCl solution has been evaluated by potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) and weight loss measurements. The product of extraction was analyzed with high performance liquid chromatography (HPLC), whose analysis shows that olive leaf extract are greatly rich in phenolic compounds, mainly Oleuropeine (OLE), Hydroxytyrosol (HT) and elenolic acid (EA). After the acid hydrolysis and high temperature of extraction, an increase in hydroxytyrosol concentration was detected, coupled with relatively low oleuropeine content and high concentration of elenolic acid. The potentiodynamic measurements have shown that this extract acts as a mixed-type corrosion inhibitor, and good inhibition efficiency is observed with the increase in HT and EA concentration. These results suggest that the inhibitive effect of olive leaf extract might be due to the adsorption of the various phenolic compounds onto the copper surface.

Keywords: olive leaf extract, oleuropein, voltammetry, copper, corrosion, HPLC, EIS

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Authors: Wei-Ru Chang, Jenn-Jiang Hwang, Zen-Ting Hsiao, Shu-Feng Lee

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Proton exchange membrane (PEM) fuel cells are widely used in electrical systems as an economical, low-polluting energy source. This study investigates the effects of PEMFC gas nitriding treatment on metal bipolar plates. The test material was SUS304 stainless steel. The study explored five different pretreatment processes, varying the corrosion resistance and electrical conductivity conditions. The most effective process was industrial acid washing, followed by heating to 500 °C. Under the condition, the corrosion current density was 8.695 μA, significantly lower than that of the untreated pretreatment sample flakes, which was measured as 38.351 μA.

Keywords: nitriding, bipolar, 304, corrosion, resistance, pretreatment

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Authors: Chun-Ying Lee, Mei-Wen Wu, Li-Yi Cheng, Chiang-Ho Cheng

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This research studies the electroplating of zinc coating in the zinc chloride bath mixed with supercritical CO2. The sodium fluoride (NaF) was used as the bath additive to change the structure and property of the coating, and therefore the roughness and corrosion resistance of the zinc coating was investigated. The surface characterization was performed using optical microscope (OM), X-ray diffractometer (XRD), and α-step profilometer. Moreover, the potentiodynamic polarization measurement in 3% NaCl solution was employed in the corrosion resistance evaluation. Because of the emulsification of the electrolyte mixed in Sc-CO2, the electroplated zinc produced the coating with smoother surface, smaller grain, better throwing power and higher corrosion resistance. The main role played by the NaF was to reduce the coating’s roughness and grain size. In other words, the CO2 mixed with the electrolyte under the supercritical condition performed the similar function as brighter and leveler in zinc electroplating to enhance the throwing power and corrosion resistance of the coating.

Keywords: supercritical CO2, zinc-electroplating, sodium fluoride, electroplating

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Authors: M. Cortés, E. Vera, O. Rojas

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The research studies of the kinetics of the corrosion process that attacks concrete and occurs within sewerage systems agree on the amount of variables that interfere in the process. This study aims to check the impact of the pH levels of the corrosive environment and the concrete surface, the concentrations of chemical sulfuric acid, and in turn, measure the resistance of concrete to this attack under controlled laboratory conditions; it also aims to contribute to the development of further research related to the topic, in order to compare the impact of biogenic sulfuric acid and chemical sulfuric acid involvement on concrete structures, especially in scenarios such as sewerage systems.

Keywords: acid sulfuric, concrete, corrosion, biogenic

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Authors: C. Amrane, D. Haman

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Aluminum-magnesium alloys are widely used in industry thanks to their mechanical properties and corrosion resistivity. These properties are related to the magnesium content and to the applied heat treatments. Although they are already well studied, questions concerning the microstructural stability and the effect of different heat treatments are still being asked. In this work we have presented a comparative study on the behavior of the precipitation reactions during different heat treatment in two different Al-Mg alloys (Al–8 wt. % Mg and Al–12 wt. % Mg). For this purpose, we have used various experimental techniques as dilatometry, calorimetry, optical microscopy, and microhardness measurements. The obtained results shown that, the precipitation kinetics and the mechanical responses to the applied heat treatments, of the two studied alloys, are different.

Keywords: Al-Mg alloys, precipitation, hardness, heat treatments

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Authors: Chahla Rahal, Philippe Refait

Abstract:

Oleuropein-rich extract from olive leaf and acid hydrolysates, rich in hydroxytyrosol and elenolic acid was prepared under different experimental conditions. These phenolic compounds may be used as a corrosion inhibitor. The inhibitive action of these extracts and its major constituents on the corrosion of copper in 0.5 M NaCl solution has been evaluated by potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) and weight loss measurements. The product of extraction was analyzed with high performance liquid chromatography (HPLC), whose analysis shows that olive leaf extract are greatly rich in phenolic compounds, mainly Oleuropeine (OLE), Hydroxytyrosol (HT) and elenolic acid (EA). After the acid hydrolysis and high temperature of extraction, an increase in hydroxytyrosol concentration was detected, coupled with relatively low oleuropeine content and high concentration of elenolic acid. The potentiodynamic measurements have shown that this extract acts as a mixed-type corrosion inhibitor, and good inhibition efficiency is observed with the increase in HT and EA concentration. These results suggest that the inhibitive effect of olive leaf extract might be due to the adsorption of the various phenolic compounds onto the copper surface.

Keywords: Olive leaf extract, Oleuropein, hydroxytyrosol, elenolic acid , Copper, Corrosion, HPLC/DAD, Polarisation, EIS

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Authors: C. Venkataraman B. E., J. Nagarajan B. E., V. Srinivasan M. Tech

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For a better understanding on sulfide stress corrosion cracking, a theoretical approach based on crystal structure, molecule behavior, flow of electrons and electrochemical reaction is developed. Its impact on different materials such as carbon steel, low alloy, alloy for sour (H2S) environments is studied. This paper describes the theories on various disaster and failures occurred in the industry by Stress Corrosion Cracking (SCC). Parameters such as pH of process fluid, partial pressure of CO2, O2, Chlorine, effect of internal pressure (crystal structure deformation by stress), and external environment condition are considered. An analytical line graph is then created for process fluid parameter verses time, temperature, induced/residual stress due to local pressure build-up. By comparison with the load test result of NACE and ASTM, it is possible to predict and simplify the control of SCC by use of materials like ferritic, Austenitic material in the oil and gas & petroleum industries.

Keywords: crystal structure deformation, failure assessment, alloy-environment combination, H2S

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Authors: Neha Parekh, Divya Ladha, Poonam Wadhwani, Nisha Shah

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Nano scaled materials have attracted tremendous interest as corrosion inhibitor due to their high surface area on the metal surfaces. It is well known that the zinc oxide nanoparticles have higher reactivity towards aqueous acidic solution. This work presents a new method to incorporate zinc oxide nanoparticles with white sesame seeds extract (nano-green inhibitor) for corrosion protection of zinc in acidic medium. The morphology of the zinc oxide nanoparticles was investigated by TEM and DLS. The corrosion inhibition efficiency of the green inhibitor and nano-green inhibitor was determined by Gravimetric and electrochemical impedance spectroscopy (EIS) methods. Gravimetric measurements suggested that nano-green inhibitor is more effective than green inhibitor. Furthermore, with the increasing temperature, inhibition efficiency increases for both the inhibitors. In addition, it was established the Temkin adsorption isotherm fits well with the experimental data for both the inhibitors. The effect of temperature and Temkin adsorption isotherm revealed Chemisorption mechanism occurring in the system. The activation energy (Ea) and other thermodynamic parameters for inhibition process were calculated. The data of EIS showed that the charge transfer controls the corrosion process. The surface morphology of zinc metal (specimen) in absence and presence of green inhibitor and nano-green inhibitor were performed using Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM) techniques. The outcomes indicated a formation of a protective layer over zinc metal (specimen).

Keywords: corrosion, green inhibitor, nanoparticles, zinc

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Authors: Satish Kolli, Adriana Ferancova, David Porter, Jukka Kömi

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Electrochemical impedance spectroscopy (EIS) has been used to detect sensitization in austenitic stainless steels that are heat treated in the temperature regime 600-820 °C to produce different degrees of sensitization in the material. The tests were conducted at five different DC potentials in the transpassive region. The quantitative determination of degree of sensitization has been done using double loop electrochemical potentiokinetic reactivation tests (DL-EPR). The correlation between EIS Nyquist diagrams and DL-EPR degree of sensitization values has been studied. The EIS technique can be used as a qualitative tool in determining the intergranular corrosion in austenitic stainless steels that are heat treated at a given temperature.

Keywords: electrochemical technique, intergranular corrosion, sensitization, stainless steels

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Authors: Ahmet Yonetken, Ayhan Erol

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The microstructure, mechanical properties and corrosion characteristics of Ni plated %10Al2O3-%40Co-%20Cr and %10Ti powders were investigated using specimens produced by tube furnace sintering at 800-1200°C temperature. A uniform nickel layer on Al2O3-Co-Cr and Ti powders was deposited prior to sintering using electroless plating technique. A composite consisting of quintet additions, a metallic phase, Ti,Cr and Co including a ceramic phase, alumina, within a matrix of Ni has been prepared under Ar shroud and then tube furnace sintered. XRD, SEM (Scanning Electron Microscope), corrosion behavior in acidic media were investigated to characterize the properties of the specimens. Experimental results carried out for composition (%10Al2O3-%40Co-%20Cr- %10Ti)20Ni at 1200°C suggest that the best properties as 312.18HV were obtained at 1200°C.

Keywords: sintering, intermetallic, Electroless nickel plating, composite

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Authors: Feng-Tsai Weng, Rick Wang, Yan-Cong Liao

Abstract:

Passivation is a kind of surface treatment for material to reinforce the corrosion resistance specially the stainless alloy. Passive film, is to getting more potential compared to their status before passivation. An oxidation film can be formed on the surface of stainless steel, which has a strong corrosion resistance ability after passivation treatment. In this research, a new passivation technology is proposed for a special stainless alloy which contains a 12-14% Chromium. This method includes the A-A-A (alkaline-acid-alkaline) process basically, which was developed by Carpenter that can neutralize trapped acid. Besides, a corrosion resistant coating layer was obtained by immersing the parts in a water bath of mineral oil at high temperature. Salt spray test ASTM B368 was conducted to investigated performance of corrosion resistant of the passivated stainless steel alloy parts. Results show much better corrosion resistant that followed a coating process after A-A-A Passivation process, than only using A-A-A process. The passivation time is with more than 380 hours of salt spray test ASTM B368, which is equal to 3000 hours of Salt spray test ASTM B117. Proposed passivation method of stainless steel can be completed in about 3 hours.

Keywords: passivation, alkaline-acid-alkaline, stainless steel, salt spray test

Procedia PDF Downloads 354

Authors: Ahmed Elbeheri, Tarek Zayed

Abstract:

Steel bridges deterioration has been one of the problems in North America for the last years. Steel bridges deterioration mainly attributed to the difficult weather conditions. Steel bridges suffer fatigue cracks and corrosion, which necessitate immediate inspection. Visual inspection is the most common technique for steel bridges inspection, but it depends on the inspector experience, conditions, and work environment. So many Non-destructive Evaluation (NDE) models have been developed use Non-destructive technologies to be more accurate, reliable and non-human dependent. Non-destructive techniques such as The Eddy Current Method, The Radiographic Method (RT), Ultra-Sonic Method (UT), Infra-red thermography and Laser technology have been used. Digital Image processing will be used for Corrosion detection as an Alternative for visual inspection. Different models had used grey-level and colored digital image for processing. However, color image proved to be better as it uses the color of the rust to distinguish it from the different backgrounds. The detection of the rust is an important process as it’s the first warning for the corrosion and a sign of coating erosion. To decide which is the steel element to be repainted and how urgent it is the percentage of rust should be calculated. In this paper, an image processing approach will be developed to detect corrosion and its severity. Two models were developed 1st to detect rust and 2nd to detect rust percentage.

Keywords: steel bridge, bridge inspection, steel corrosion, image processing

Procedia PDF Downloads 296

Authors: S. W. Liu, J. H. Lv, W. Z. Wang

Abstract:

In recent years, the failure accidents in petrochemical industry have been frequent, and have posed great security problems in personnel and property. The improvement of petrochemical safety is highly requested in order to prevent re-occurrence of severe accident. This study focuses on surveying the failure cases occurred in petrochemical field, which were extracted from journals of engineering failure, including engineering failure analysis and case studies in engineering failure analysis. The relation of failure mode, failure mechanism, type of components, and type of materials was analyzed in this study. And the analytical results showed that failures occurred more frequently in vessels and piping among the petrochemical equipment. Moreover, equipment made of carbon steel and stainless steel accounts for the majority of failures compared to other materials. This may be related to the application of the equipment and the performance of the material. In addition, corrosion failures were the largest in number of occurrence in the failure of petrochemical equipment, in which stress corrosion cracking accounts for a large proportion. This may have a lot to do with the service environment of the petrochemical equipment. Therefore, it can be concluded that the corrosion prevention of petrochemical equipment is particularly important.

Keywords: cases analysis, corrosion, failure, petrochemical industry

Procedia PDF Downloads 295