Steel In Natural Seawater Research Articles

Application of natural materials in marine paint formulations

PurposeTrials to develop environmentally friendly marine paints based on natural materials as replacement for copper and tin compounds for fouling and marine corrosion control.Design/methodology/approachGreen algae, tubeworms in dead powder form and garlic were used as natural anti‐fouling components in the paints developed. Electrochemical technique was employed for testing the potential of both tubeworms and garlic in terms of inhibition of steel corrosion in seawater. Marine paint formulations containing each of the three selected natural materials were applied onto PVC and un‐primed steel surface, which were immersed in natural seawater for the assessment of their anti‐fouling and anti‐corrosion properties. The results of visual assessment and seawater analysis were also used for such an evaluation.FindingsTubeworms act as mixed type inhibitor while garlic affects the potential cathodic process of steel in seawater. Tubeworms‐based paint, with 25 per cent in the dry paint film, could protect steel surface from marine corrosion up to 7 months. The paints containing algae and garlic, and the corresponding algae/garlic free paints, resisted slime film formation. Steel and PVC coated surfaces with paint containing algae showed the best anti‐fouling potential within the prepared series.Research limitations\implicationsThe investigation only involved the application of the dead form of green algae and tubeworms as effective pigments in the developed paints. It is recommended that further research should focus on extracting and identifying the active components in each organism against fouling and marine corrosion.Practical implicationsThe paint formulations developed (containing 25 per cent by weight tubeworms in the paint film) could be used to protect un‐primed steel surface against fouling and marine corrosion for a reasonably long duration.Originality/valueThe application of one paint formulation on un‐primed steel surface for its protection from both fouling and marine corrosion is novel. The electrochemical studies of steel in natural seawater in presence of tubeworms and garlic are original.

海水中でのSUS 304ステンレス鋼の自然浸漬電位におよぼす照度の影響

海水中でのSUS 304ステンレス鋼の自然浸漬電位におよぼす照度の影響

自然海水中に浸漬したステンレス鋼の電位貴化メカニズムの検討

自然海水中に浸漬したステンレス鋼の電位貴化メカニズムの検討

EIS and XPS study of the corrosion of carbon steel in inhibited natural seawater

Electrochemical and surface analytical techniques were used to study the corrosion behaviour of a carbon steel in inhibited seawater. Linear polarization resistance and Tafel polarization measurements showed the effect of inhibitor injection on the corrosion rate of carbon steel in natural seawater. A 90% reduction in the corrosion rate was observed for the steel under investigation. In situ electrochemical impedance spectroscopy (EIS) measurements indicated that the inhibiting film formed in seawater was stable and no pitting corrosion was observed. Surface analysis of steel samples by XPS revealed conclusively that the inhibiting film was three-dimensional in nature because the steel surface was essentially buried under it. Copyright © 1999 John Wiley & Sons, Ltd.

Detection of localized corrosion of stainless steels by optical interferrometry

An optical corrosion meter has been developed for materials testing and evaluation of different corrosion phenomena. The meter was based on principles of 3D holographic interferrometry for measuring microsurface dissolution, i.e. mass loss, and on those of electrochemistry for measuring the bulk electronic current, i.e. corrosion current of metallic samples in aqueous solutions. The early stage of pitting corrosion of UNS No. 304 stainless steel and crevice corrosion of UNS 316 stainless steel in natural seawater were monitored, in situ by the optical corrosion meter during the cyclic polarization tests. The observations of pitting corrosion were basically interferrometric perturbations detected on the surface of the UNS No. 304 stainless steel in seawater. In contrast, the observations of crevice corrosion were basically interferrometric perturbations detected on the surface of the UNS No. 316 stainless steel underneath a crevice assembly. Eventually, the interferrometric perturbations were interpreted as localized corrosion in the form of an early pitting or of an early crevice corrosion, of a depth ranging from 0.3 μm to several micrometers. Consequently, holographic interferrometry is shown to be a useful technique as a 3D-interferrometric microscope for monitoring pitting corrosion or crevice corrosion at the initiation stage of both phenomena for different metallic samples in aqueous solutions.

自然海水中ステンレス鋼の自然電位貴化におよぼすバクテリアの影響

自然海水中ステンレス鋼の自然電位貴化におよぼすバクテリアの影響

Effect of bacterial biofilm on 316 SS corrosion in natural seawater by eis

The electrochemical behavior of AISI 316 stainless steel in natural seawater collected from Canary Archipelago was investigated. A comparative study on a large number of samples immersed during three weeks in this environment with and without sulfate-reducing bacteria (SRB) was made. Open circuit potential measurements, cyclic polarization, Scanning Electron Microscopy (SEM) and Electrochemical Impedance Spectroscopy (EIS) were used. The obtained results permitted an interpretation of the contribution of biofilms to corrosion of stainless steel and a mechanism of the process is checked.

自然海水中ステンレス鋼の自然電位貴化におよぼす珪藻の影響

自然海水中ステンレス鋼の自然電位貴化におよぼす珪藻の影響

ステンレス鋼の海水中での微生物腐食とその抑制に及ぼす表面性状の影響

ステンレス鋼の海水中での微生物腐食とその抑制に及ぼす表面性状の影響

海水中におけるステンレス鋼の微生物腐食

海水中におけるステンレス鋼の微生物腐食

Microbially influenced corrosion of stainless steels in natural seawater

Microbially influenced corrosion of stainless steels in natural seawater

海水中におけるステンレス鋼の微生物腐食機構

Stainless steels, such as types 316L and 304 have high susceptibilities to pitting and crevice corrosion in natural seawater even though they have low susceptibilities in synthetic seawater. Recently, this type of corrosion has been recognized as a kind of Microbially Influenced Corrosion (MIC) in aerobic aqueous environments. The mechanism of MIC on stainless steels in natural seawater is studied by the electrochemical and biological techniques. Measurements of cathodic polarization curves of stainless steels were carried out in natural and synthetic seawater. The corrosion potential of stainless steels was measured in seawater and culture medium of the bacteria isolated from natural seawater. The corrosion potential of stainless steels became noble in natural seawater compared with synthetic seawater, and the cathodic polarization behavior indicates that some substances exist, which have higher redox potential than that of oxygen. It has become clear that the susceptibility to corrosion of stainless steels in natural seawater is effected by bacteria in the mature biofilm. As a result of the experiment using isolated bacteria, the corrosion potential became noble in the logarithmic phase of bacterial growth. These results suggest that the aerobic metabolism of the bacteria causes the ennoblement of stainless steels. Hydrogen peroxide, which could be generated due to the reduction of oxygen in the presence of enzyme (oxidase), was detected in the mature biofilm. Hydrogen peroxide has a higher redox potential than that of oxygen. Therefore, this result supports the fact that the hydrogen peroxide, as an intermediate substance in the aerobic metabolism of bacteria in the biofilm, causes the ennoblement of stainless steels in natural seawater. The potential ennoblement and the occurrence of crevice corrosion of stainless steels were successfully reproduced in the laboratory by using the synthetic seawater with the addition of oxidase and substrate.

Applications of the scanning reference electrode technique to localized corrosion

A new commercially-designed instrument using the Scanning Reference Electrode Technique (SRET) has enabled the measurement of localized current densities in the vicinity of pits in Type 304 stainless steel in natural seawater. The results demonstrate the scope for improved quantitative models of localized corrosion using this technique.

Impact of biofouling on the electrochemical behaviour of 304 stainless steel in natural seawater

Biofilm formation on 304 stainless steel (S30400) does not necessarily result in an ennoblement of the corrosion potential. Instead, biofilms composed of aerobic and anaerobic bacteria from Gulf of Mexico water formed an anaerobic biofilm/metal interface and caused the corrosion potential to move in the negative direction. Biofilms from the same source containing photosynthetic diatoms in the presence of light produced aerobic biofilm/metal interfaces and a positive shift (ennoblement of the corrosion potential). Corrosion potentials of stainless steels exposed in natural seawater cannot be predicted without an understanding of the composition of the biofilm and its impact on interfacial chemistry. In this paper, measurements of corrosion potential, interfacial pH and dissolved oxygen have been correlated with SEM/EDAX surface analyses to evaluate the electrochemical behaviour of stainless steels exposed to Gulf of Mexico water. The interfacial chemistries that influence the corrosion potential are also d...

Corrosion fatigue crack arrest in aluminum alloys: basic data: Wanhill, R.J.H. and Schra, L. Report No. NLR TR 87128 U

Measurements of the potential gradients along real, and simulated cracks have been made for an HY80 steel in natural seawater and on simulated cracks for a C-Mn steel in a CO2-3/HCO-3 solution. The simulated crack cell also allowed measurement of the current flow in the crack enclave. The results show that large potential drops only occur along cracks if attempts are made to pass relatively large currents along the crack enclave, so that if the applied potential is not too far removed from the free corrosion potential or the environment is one that promotes passivation of the steel surface then any initial potential drop will decay relatively quickly.

Corrosion fatigue: Schutz, W. Int. J. Mater. Prod. Technol. 1988, 3, (1), 20–37

Measurements of the potential gradients along real, and simulated cracks have been made for an HY80 steel in natural seawater and on simulated cracks for a C-Mn steel in a CO2-3/HCO-3 solution. The simulated crack cell also allowed measurement of the current flow in the crack enclave. The results show that large potential drops only occur along cracks if attempts are made to pass relatively large currents along the crack enclave, so that if the applied potential is not too far removed from the free corrosion potential or the environment is one that promotes passivation of the steel surface then any initial potential drop will decay relatively quickly.

Cathodic Performance of Stainless Steels in Natural Seawater as a Function of Microorganism Settlement and Temperature

Abstract The modification of oxygen reduction rate induced by bacterial settlement on stainless steel (SS) surfaces immersed in natural seawater was studied as a function of temperature (25 C≤tempe...

Crevice Corrosion Resistance of Stainless Steels in Natural Seawater in the Temperature Range of 25 to 40 C

Abstract The influence of temperature in the range of 25 to 40 C on crevice corrosion of certain stainless steels (SSs) is studied by field tests performed in natural seawater. The increase in temp...

Cathodic Properties of Different Stainless Steels in Natural Seawater

Abstract The cathodic properties of a number of stainless steels, which were exposed to natural seawater flowing at 0 to 2.5 m/s and polarized to potentials from −300 to −950 mV SCE, have been studied. The current density development at constant potential and the free corrosion potential during the exposure time were recorded continuously. At the end of the exposure period, after approximately 28 to 36 days of exposure, polarization curves were determined. After one to three weeks of exposure, depending on the water velocity, microbiological activity on the surface caused an increase in the current density requirement of the specimen. An explanation for the mechanism behind the current density increase caused by slime production from marine bacteria may be increased exchange current density, i0. There was no measurable calcareous deposit on the stainless steel surfaces at the end of the exposure periods.

Corrosion and corrosion-fatigue properties of 10KhSND steel in natural sea water and in a medium saturated with marine bacteria

Corrosion and corrosion-fatigue properties of 10KhSND steel in natural sea water and in a medium saturated with marine bacteria