Corrosion Of Steel In Seawater Research Articles

Cuprous ions influence on the biocorrosion of a carbon steel in the presence of sulphate reducing bacteria marine biofilm

The influence of marine sulphate reducing bacteria (SRB) biofilm on naval carbon steel corrosion in seawater was studied in the presence or not of cuprous ions as polluting agent. The optical density measurement showed that a concentration of 15 mg L−1 in cuprous ions can cause a significant slowdown in the proliferation of planktonic bacteria. However, electrochemical impedance results indicated that there was still bacterial activity on the metal substrate. Indeed, biofilm was grown on the surface of material in seawater containing SRB. Initially, an increase in the charge transfer resistance values due to the iron sulphide layer formed by the bacteria precipitation reactions was recorded during growth phase. This film acts as a barrier, preventing further oxidation of the underlying metal; then, the localized breakdown of iron sulphide layer generates an acceleration of corrosion. Similar behaviour occurs in the presence of sulphate reducing bacteria flora with 15 mg L−1 cuprous ions. In order to protect themselves when the seawater media containing toxic metals, sulphate reducing bacteria embed into clusters and increase the production of extracellular polymeric substances on materials. Sulphur was present on specimens in both cases and EDS spectra revealed the formation of iron sulphide. After the removal of biofilm, carbon steel surfaces exhibited a plenty of micropits scattered on the entire surface compared to the surface immersed in the seawater without bacteria.

Study on the performance of green corrosion inhibitor in protection of API5LX60 in seawater environment

The corrosion inhibition of metals in seawater can be achieved by the addition of inhibitors to the system that prevent corrosion from taking place on the metal surface. The effect of ascorbic acid on carbone steel corrosion in seawater were investigated by means of different techniques: gravimetric method, electrochemical polarization and electrochemical impedance spectroscopy and the scanning electron microscopy (SEM). The results obtained show that the acid ascorbic effectively inhibits the corrosion of steel X60. The optimal inhibitory efficiency is obtained at a concentration of 0.05 g/L of the inhibitor, with a maximum value of 77%. This inhibitor presents a mixed inhibition character. SEM studies confirm the absence of the deterioration products on the surface of the specimens.

Localized Corrosion of Mooring Chain Steel in Seawater

Corrosion of mooring chains is regarded as one of main threats to the offshore mooring systems. Localized corrosion is even more dangerous than uniform corrosion because it may not show significant mass loss but it can cause stress concentration and initiate cracks under force, leading to accelerated degradation of mooring chains. Localized corrosion of steel in seawater is influenced by many factors such as the local heterogeneities of the steel, and the local electrochemical and microbiological environments. It is difficult to predict and the mechanism is not fully understood. The aim of this work was to study the mechanism of localized corrosion on mooring chain steel in seawater which is helpful in the search for corresponding monitoring tools and mitigation methods. The corrosion behavior of chain steel grade R4 was studied in artificial seawater and artificial seawater containing microorganisms collected from a practice field. The corrosion behavior of the steel was studied using different techniques such as potentiodynamic polarization, linear polarization resistance measurements and electrochemical impedance spectroscopy. The microstructures such as inclusions and compositions of the chain steel were studied using SEM: Scanning Electron Microscope and EDS: Energy Dispersive Spectroscopy. The microbial cells were observed using epi-fluorescence microscopy. The corrosion morphology and pit geometry were investigated using photo-microscopy. The localized corrosion rate has been found to be much higher than the uniform corrosion rate of the steel in the seawater in the presence of bacteria. In the case of localized corrosion, applying uniform corrosion measurement techniques and formulas is not considered representative. The representative areas have to be introduced to match physical results with the measurements. Inclusions, such as MnS and TiVCr found in the steel have a critical influence on localized corrosion. The corrosion mechanism of the steel in seawater is discussed.

Fabricating of grape seed proanthocyanidins loaded Zein-NaCas composite nanoparticles to exert effective inhibition of Q235 steel corrosion in seawater

Grape Seed Proanthocyanidins (GSP), underutilized by-products, exhibit encouraging biological activities, but their structural instability limits practical applications. A solution to this problem was found here by using GSP-loaded zein– sodium caseinate (NaCas) composite nanoparticles. Core-shell biopolymer nanoparticles were fabricated by antisolvent precipitation method to form NaCas stabilized zein core nanoparticles. The GSP-loaded zein-NaCas composite nanoparticles were self-assembled into spherical nanoparticles with homogeneous distribution (PDI around 0.2) and high negative charge (about –30 mV). FTIR analysis indicated that hydrogen bonding, hydrophobic and electrostatic attractions act as the main energy for the formation of colloidal particles. Stability test showed that the particles have stable corrosion inhibition efficiency for Q235 steel within 15 d in a wide range of ionic strength and pH value, and thus can adapt to the changes of seawater environment. Corrosion results manifested that GSP-loaded zein-NaCas composite nanoparticles display good re-dispensability and controlled release performance, whose inhibitive efficiency for Q235 steel in seawater is obviously higher than that of GSP (200 mg/L, 96.06% versus 71.89%).

Influence of Mg2+ Ions on the Formation of Green Rust Compounds in Simulated Marine Environments

Green rust compounds (GR), i.e., Fe(II-III) layered double hydroxides, are important transient compounds resulting from the corrosion of steel in seawater. The sulfated variety, GR(SO42−), was reported as one of the main components of the corrosion product layer, while the chloride variety, GR(Cl−), was more rarely observed. The carbonate variety, GR(CO32−), is favored by an increase in pH and forms preferentially in the cathodic areas of the metal surface. Since Mg(II) is abundant in seawater, it may have a strong influence on the formation of GR compounds, in particular as it can be incorporated in the hydroxide sheets of the GR crystal structure. In the present work, the influence of Mg2+ on the precipitation reaction of GR(SO42−) was investigated. For that purpose, Mg2+ was substituted, partially or entirely, for Fe2+. The GR was then prepared by mixing a solution of FeCl3·6H2O, Na2SO4·10H2O, NaCl, FeCl2·4H2O and/or MgCl2·4H2O with a solution of NaOH. The precipitation of the GR was followed or not by a 1-week aging period. The obtained precipitate was characterized by X-ray diffraction. It was observed that Mg(II) favored the formation of chloride green rust GR(Cl−) and magnetite Fe3O4 at the detriment of GR(SO42−). The proportion of GR(Cl−) and Fe3O4 increased with the Mg(II):Fe(II) substitution ratio. Without Fe(II), the precipitation reaction led to iowaite, i.e., the Mg(II)-Fe(III) compound structurally similar to GR(Cl−). It is forwarded that the presence of Mg2+ cations in the hydroxide sheets of the GR crystal structure is detrimental for the stability of the crystal structure of GR(SO42−) and favors the formation of other mixed valence Fe(II,III) compounds.

THE ASSESSMENT OF INHIBITIVE EFFECT OF CYMBOPOGON CITRATUS ON MARINE CORROSION OF MILD STEEL

Numerous extensive efforts have been done to acquire the applicable green corrosion inhibitors in order to decrease the corrosion rate of the materials. The corrosion inhibition of mild steel is vital for technology due to the increased industrial applications of these materials. In this report, the inhibitive action of Cymbopogon Citratus on the marine corrosion of mild steel was evaluated. The inhibition efficiency was calculated using weight loss measurement method, electrochemical measurement and inhibitor mechanism analysis. It was found that, Cymbopogon Citratus exhibited a very good performance as a green corrosion inhibitor for mild steel corrosion in seawater. All the experimental methods used for this project show that the presence of Cymbopogon Citratus in the seawater significantly decreases the corrosion rates and further decreasing the corrosion rates as the concentration of Cymbopogon Citratus increases. To sum it up, the inhibition efficiency increases with an increase in Cymbopogon Citratus concentration.

Synergistic Inhibition of Mild Steel Corrosion in Seawater and Acidic Medium by Cathodic Protection and Monodora myristica Using Zinc Anode

The synergistic inhibition of mild steel corrosion in seawater and 0.1M sulphuric acid by the cathodic protection and Monodora myristica was carried out through the weight loss and the linear polarization resistance (LPR) measurement. The results showed that in seawater, the synergism was not too effective for the protection of steel, whereas in 0.1M sulphuric acid, there was a great synergism between cathodic protection and the oil extracts of Monodora myristica, having an efficiency (IE%) of 102.89% at 15 mL of the oil extracts. For the linear polarization resistance (LPR), in most of the cases, there was a slight shift of the corrosion potential (Ecorr) and the open circuit potential (OPC) toward the positive as the volume of the oil extracts increased, thereby causing a change in the cathodic and the anodic Tafel slopes, which showed that the inhibitor is a mixed- type inhibitor. The corrosion current density (icorr) decreases as the volumes of the oil extract increase. Langmuir adsorption isotherm fitted best with an R2 of 1 unit, indicating a good agreement with the experimental data and with Langmuir adsorption isotherm.

Synergistic Inhibition Effect of Sodium Tungstate and Zinc Sulphate on Mild Steel Corrosion in Seawater

Synergistic Inhibition Effect of Sodium Tungstate and Zinc Sulphate on Mild Steel Corrosion in Seawater

The Secant Rate of Corrosion: Correlating Observations of the USS Arizona Submerged in Pearl Harbor

Contrary to previous linear projections of steel corrosion in seawater, analysis of an inert marker embedded in USS Arizona concretion since the 7 December 1941 attack on Pearl Harbor reveals evidence that the effective corrosion rate decreases with time. The secant rate of corrosion, or SRC correlation, derived from this discovery could have a significant impact on failure analysis investigations for concreted shipwrecks or underwater structures. The correlation yields a lower rate of metal thinning than predicted. Development of the correlation is described.

Corrosion Protection Of Mild Steel In Sea Water Using Chemical Inhibitor

The effect of sodium nitrite as a corrosion inhibitor of mild steel in sea water (i.e ASTM standard prepared sea water and sea water obtained from a local river) was investigated, using the weight loss technique. Different amount of sodium nitrite were prepared (i.e 2 % to 10 %) in the inhibition of the mild steel corrosion in sea water exposed to irradiation condition from sunlight exposure. The cut samples of mild steel were exposed to these corrosive media and the corresponding weight loss subsequently obtained was recorded at intervals of 1 to 4 weeks. It was observed that corrosion rate increases with the time of exposure to the corrosive medium exposed to sunlight and that sodium nitrite that was used at the chemical inhibitor was able to retard the corrosion rate of mild steel if the appropriate concentration is applied. The results obtained from the weight loss analysis shows that the optimum percentage of sodium nitrate in sea water that gives the optimum corrosion inhibition of mild steel is 4 %.

Synergistic Effect of Iron Bacteria and Vibrio on Carbon Steel Corrosion in Seawater

The microbiologically influenced corrosion and electrochemical behavior of 45 steel were investigated in the presence of vibrio and iron bacteria using the mass loss determination, electrochemical analysis method and surface analysis method. The results showed that the corrosion of 45 steel was accelerated for the presence of the two bacterial species. 45 steel immersed in mixed medium containing both vibrio and iron bacteria showed a lower free corrosion current potential and a decrease in impedance with immersion time. Scanning electron microscopy (SEM) revealed that the mixed bacteria system caused more severe pitting corrosion of carbon steel.

Effect of extracellular polymeric substances isolated from Vibrio natriegens on corrosion of carbon steel in seawater

Extracellular polymeric substances (EPS) are isolated from marine Vibrio natriegens (V. natriegens) by a cation exchange resin method. The influences of EPS concentration and corrosion time on the corrosion of carbon steel in seawater are investigated. The results demonstrate that EPS are capable of forming a protective film on the surface of carbon steel in seawater, which retards the diffusion of dissolved oxygen and inhibits the reduction of oxygen on the cathode. In addition, the efficiency of corrosion inhibition increases with an increase in the amount of added EPS during the initial state (the first 3 days); however, excess EPS (exceeding 300 mg L−1) in seawater significantly accelerates the corrosion of carbon steel over the long term (10 days) due to the binding power of EPS with Fe ions.

COMPARATIVE STUDY OF CORROSION INHIBITORS FOR REBAR STEELS IN SIMULATED PORE SOLUTION CONTAINING SEAWATER AND CARBONATES

The performances of sodium nitrite and dimethylethanolamine (DMEA) inhibitors have been compared in mitigating corrosion of rebar steels in simulated pore solution containing sea water and carbonates. The simulated solution was prepared by dissolving saturation amounts of alkali hydroxides and sulphates in sea water and adding carbonates subsequently. The inhibitor of sodium nitrite and DMEA with various concentration was then added to the respective simulated solution. The corrugated rebar steels were immersed in the solutions and electrochemical corrosion was measured using potentiodynamic polarization method. The experimental results showed that sodium nitrite exhibited more effective performance compared to DMEA in mitigating rebar steel corrosion in sea water and carbonated media. The lowest steel corrosion rate of 0.27 M Sodium nitrite with 0.3 M concentration decreased corrosion rate of the steel to 0.27 M , the lowest values of the measured corrosion rates this work.

The Inhibition Effect of Polyaspartic Acid and Its Mixed Inhibitor on Mild Steel Corrosion in Seawater Wet/Dry Cyclic Conditions

The inhibition effects of polyaspartic acid (PASP) and the mixed inhibitor (50mg/L PASP, 100mg/L Na2WO4, 100mg/L ZnSO4 center dot 7H(2)O) on mild steel corrosion in seawater wet/dry cyclic conditions were studied via weight loss and electrochemical methods. The polarization curves show that the inhibition efficiency is 72.4% in the presence of PASP, and rises up to 92.6% after the addition of the mixted inhibitor. Scanning electron microscopy (SEM), X-ray diffraction and Fourier transform infrared reflection were performed to study the corrosion inhibition effect. According to the results of SEM, the metal surface immersed in the mixed inhibitor was better protected than that in PASP due to the formation of a protective film.

Synergistic inhibition of carbon steel corrosion in seawater by cerium chloride and sodium gluconate

In this research the effect of cerium (III) chloride heptahydrate (CC) and sodium gluconate (SG) on the corrosion inhibition of carbon steel C45 (1531) in natural seawater has been evaluated using electrochemical methods and scanning electron microscopy (SEM). The results show that substantial corrosion inhibition (94.98%) using CC and SG can be obtained in synergistic manner. Surface analysis confirmed the presence of cerium ions incorporated in the protective layer of carbon steel specimen. SG acts predominantly as anodic inhibitor whereas CC acts as a mixed type inhibitor. Using both inhibitors predominant mechanism of anodic inhibition is observed.

Analysis of AISI 1020 steel corrosion in seawater by coupling electrochemical noise and optical microscopy

Electrochemical noise coupled to in situ optical micrographs was used to study corrosion processes in AISI 1020 steel immersed in seawater. The noise data was analysed using wavelet transform. The results were represented in energy diagrams and showed that considerable changes occurred in the corrosion mechanism during the initial step of the experiment (until 7200s). During this initial step, it was observed that the corrosion was predominantly localized by means of pitting formation and intergranular corrosion. After approximately 50,000s (14h) of immersion, general corrosion processes become dominant. The conclusions obtained from the analysis of the current noise signal using the wavelet transform were confirmed by optical micrograph which suggests that the coupling of electrochemical noise and optical microscopy techniques can be valuable in studying corrosion processes in this system. Another advantage of this procedure is the elucidation and separation of corrosion processes, such as, for example, pitting and intergranular ones, that are not commonly identified by other techniques.

Localized Electrochemical Corrosion Characteristics of Carbon Steel in Seawater

The galvanic and potential distributions of carbon steel immersed in seawater were studied by wire beam electrode (WBE) technique. Results indicated that the corrosion of carbon steel in seawater tended to local corrosion. With immersion time increasing, local corrosion was more and more serious. During the initial immersion period, the top of the coupon near the water surface was main cathode. With the corrosion extended, corrosion products gradually gathered on the surface of the carbon steel. Potential differences between cathode and anode gradually became small. Cathode and anode redistributed on the surface of carbon steel. At last, the top and the bottom were cathode while the middle was anode. The areas of anode first increased and then decreased. The areas of cathode were in contrast.

The inhibition effect of tannic acid on mild steel corrosion in seawater wet/dry cyclic conditions

The inhibition effect of tannic acid on mild steel corrosion in seawater wet/dry cyclic conditions was studied by weight loss and electrochemical methods. Result of the polarisation curves shows that corrosion current density decreases from 47.85μAcm−2 to 6.67μAcm−2 after tannic acid is added; charge transfer resistance remains stable in the electrochemical impedance spectra. Scanning electron microscopy, X-ray diffraction, and Fourier transform infrared reflection are performed to study the corrosion inhibition. The inhibition effect of the compound is attributed to ferric tannate film formation on the steel surface, which is relatively stable during wet/dry cycles.

Inhibitory Mechanism of Carbon Steel Corrosion in Sea Water by an Aqueous Extract of Henna Leaves

The inhibition efficiency (IE) of an aqueous extract of henna leaves in controlling corrosion of carbon steel in seawater has been evaluated by weight-loss method. The weight loss study reveals that the formulation consisting of 8 mL of henna extract (HE) and 25 ppm of Zn2+has 94% inhibition efficiency in controlling corrosion of carbon steel in sea water. Polarization study reveals that HE and Zn2+system functions as mixed type inhibitor. AC impedance spectra reveal that protective film is formed on the metal surface. The nature of the metal surface has been analysed by FTIR spectra, SEM, and AFM analysis.

Inhibitory Action of Phyllanthus Amarus Extracts on the Corrosion of Mild Steel in Seawater

Inhibitory action of Phyllanthus amarus extracts on the corrosion of mild steel in seawater was studied by weight loss method and potentiodynamic polarization technique. The potentiodynamic polarization results reveal that the leaves extract behaved like anodic type inhibitor. Maximum inhibition efficiency of Phyllanthus amarus in seawater was found to be 98%. The protective film has been analyzed using Fourier transform infrared (FTIR) spectroscopy and Fluorescence spectroscopy.