Electrochemical Behavior Of Steel Research Articles

The Effect of Organic Compounds on the Electrochemical Behaviour of Steel in Acidic Media. A review.

The Effect of Organic Compounds on the Electrochemical Behaviour of Steel in Acidic Media. A review.

Effects of anaerobe in sea bottom sediment on the corrosion of carbon steel

AbstractThe in‐situ study of steel corrosion in sea bottom sediment (SBS) was carried out by Transplanting Burying Plate method (TBP method). It was found that the corrosion rate of steel in the sea bottom sediment with sulfate reducing bacteria (SRB) could be as high as ten times of that in sea bottom sediment without SRB. The experiments in simulated sea bottom sediments with different SRB contents by artificial culturing showed that the electrochemical behavior of steel in the sea bottom sediment with SRB was different from that without SRB. SRB altered the polarization behavior of steel significantly. The environment was acidified due to the activity of SRB and the corrosion of steel was accelerated. The corrosion of carbon steel in sea bottom sediment is anaerobic corrosion, and the main factor is anaerobe. There are SRB commonly in SBS, and the amount of SRB decreases along with the depth of sediment. Because of the asymmetry and variation of sea bottom sediment, the most dangerous corrosion breakage of steel in SBS is local corrosion caused by SRB. So the main countermeasure of corrosion protection of sea bottom steel facilities should be controlling of the corrosion caused by anaerobe.

Improved Electrochemical Determinations of Chloride-Induced Steel Corrosion in Concrete

A significant amount of infrastructure is located in a marine environment or in environments where high levels of chloride are present. Current specification methods are generally lacking in regard to predicting service life of reinforced concrete (RC) structures in aggressive environments and qualitative judgments are typically used to make predictions concerning service life. Much research has focused on prediction of chloride diffusion coefficients where more quantitative links to service life can be established. The problem with such techniques is that assumptions of the chloride threshold level for steel depassivation must be made, and this introduces generally unacceptable levels of uncertainty for asset owners. One approach appears to lie in improving the understanding of the electrochemical behavior of steel in concrete such that more accurate predictions of service life can be derived in the future. Work presented in this paper relates to the analysis of a significant amount of data on electrochemical corrosion rates of steel in concrete.

Electrochemical behavior of stainless steel W.Nr. 1.4301 in the malic acid and sulfur dioxide solution

In our earlier investigation on stainless steel W.Nr. 1.4301, corrosion damage was observed when the steel was in the contact with fruit pulps and pectin which had been conserved with SO 2. In order to understand the corrosion behavior of stainless steel W.Nr. 1.4301, which is used in equipment for the production and the conservation of fruit pulps, the electrochemical behavior of the steel in an electrolyte which contained SO 2 and malic acid (which is the most abundant fruit acid in fruit pulp) was studied. It was shown that, in the presence of malic acid, at potentials close to the corrosion potential, the stainless steel is completely passive in 0.1 M Na 2SO 4 and, at potentials more positive than 0.7 V, two parallel processes occur: dissolution of the steel and anodic oxidation of malic acid into acetaldehyde. It was already observed that, in the presence of malic acid and sulfur dioxide, the anodic process of stainless steel dissolution is accelerated and has a pitting form. In the presence of SO 2, some acceleration of the cathodic process on stainless steel occurs as a consequence of SO 2 reduction. The obtained results indicate that the observed corrosion of process equipment made of stainless steel W.Nr. 1.4301 is caused mainly by the presence of SO 2 in the fruit pulp.

Impact of biological factors on the ennoblement of stainless steel in Baltic seawater

Open circuit potentials of stainless steels increased when immersed in the Baltic Sea. The ennoblement potential was +200 mVsce in 40 to 50 days when sea water temperature was below 52°C and +300–400 mVsce within <40 days at around 102°C. Ennoblement occurred in a laboratory ecosystem at 232°C in 20 to 30 days, and at 262°C in <20 days, but no ennoblement occurred at A322°C within 40 days. By the time the ennoblement was complete, compact microcolonies covered 1–10% of the steel surface. Nutrient enrichment of Baltic Sea water by twofold above the natural levels increased microbial growth but attenuated open circuit potential increase of the stainless steels. Exposure of the ennobled stainless steels to similar levels of nutrients did not reverse the already developed open circuit potentials. Attenuation of the ennobling response of the stainless steels by increases of temperature and eutrophication suggests a role for microorganisms which is crucial for the electrochemical behaviour of steels in brackish Baltic Sea water. Journal of Industrial Microbiology & Biotechnology (2000) 24, 410–420.

Specific features of the electrochemical behavior of steels under corrosion cracking of pipelines

We analyze the role of external and internal factors in stimulation of processes of stress cracking of pipelines. We identify the number of successive stages that cause fracture of pipelines. We experimentally established that passivation of a pipe steel in electrolyte under the coating and formation of a passive film consisting of oxides and iron carbonates is the main stage of corrosion cracking. Under the action of activating factors, the breakdown of a passive film occurs and local sites of corrosion appear. This stage is determined by the composition of the electrolyte under the insulated coating, the state of the surface of the metal, and its nature. Then pittings are transformed into microcracks in the field of tensile stresses. At the final stage, microcracks form colonies, which join together into the main crack. We established the similarity of cracks formed in actual gas pipelines and cracks initiated under laboratory conditions. We investigate the corrosion-electrochemical behavior of 09G2BT steel in NaHCO3 solutions of various concentrations. We established that a decrease in the concentration of a solution leads to an increase in the density and depth of pittings. We draw a conclusion about the probabilistic character of initiation of pittings on the surface of steel, which is described by the Poisson law. We propose to use the density of pittings and the current in a single pitting for the early diagnostics of fracture of pipelines.

Electrochemical Behavior of Steel in Concrete and Evaluation of the Corrosion Rate

Abstract Various electrochemical methods for evaluation of corrosion of steel reinforcement in concrete were studied regarding their applicability in the field. Laboratory experiments were carried ...

Effect of copper cation on electrochemical behaviour of steel in presence of imidazole in acid medium

The influence of different concentrations of imidazole in the presence of 1 M sulphuric acid on electrochemical and corrosion behaviour of steel both with and without different concentrations of copper cation Cu ++ was studied potentiokinetically. It was found that imidazole reduces the corrosion current, corrosion rate and increases the polarization resistance to a great extent. For each additive, the protective cation was incorporated into the protective layer formed on the electrode surface during exposure to the tested solution. It was found that at a concentration of 10 −4 M, Cu cation strongly inhibited the corrosion rate. The corrosion of the steel in 1 M M 2SO 4 is appreciably reduced by imidazole in combination with metallic copper cation, as a result of coadsorption. At a higher concentration of the copper cation (10 −3 M) in association with the inhibitor, the dissolution of the steel is increased owing to the cathodic reduction of the metallic cation to metal. The increase in the corrosion rate is a result of cationic reduction, and the potential is shifted towards electropositive direction, indicating a new anodic and cathodic polarization curve formation resulting from the deposition of the metal. In the presence of imidazole and lower metallic copper cation concentrations (10 −5 M), the potentials shift in the electronegative direction, indicating suppression of the cathodic reaction by conjoint adsorption of the inhibitor and metallic cation. The corrosion potential, corrosion current, corrosion rate, polarization resistance, as well as activation energy and thermodynamic parameters were calculated at different temperatures. The temperature coefficient for corrosion inhibition has a negative value which may be explained by assuming that the corrosion reaction is no longer the simple metal/acid reaction, but involves the adsorbed species directly.

Corrosion resistance of composite TiN-TiC layers deposited on tool steels by different techniques

TiC layers were formed by the low-pressure chemical vapour deposition (LPCVD) technique on tool carbon steel (0.9 wt% C;0.4 wt%Si;0.5 wt% Mn), bare or nitrided by glow discharge with formation of zones consisting of (e + γ′) and (γ′) phases. The composite TiN-TiC layers were formed by the deposition of TiN on the coated TiC layers, by a pressure-assisted chemical vapour deposition (PACVD) technique or by TiC sputtering in nitrogen under glow discharge conditions. The electrochemical behaviour of the metal/coating has been established by potentiodynamic tests done in acid (20% H3PO4) and alkaline (0.1 n NaOH) solutions. The deposited layers protect the steel by decreasing the steel area exposed to the aggressive solution and by promoting steel passivation. The protective ability of composite TiN/TiC layers is higher than that of corresponding single layers. Improvement of the protective ability of LPCVD TiC layers is achieved by the deposition conditions, providing the formation of fine grains 〈111〉 texture. The electrochemical behaviour of steel coated with complex TiN/TiC layers approaches the intrinsic electrochemical behaviour of TiN.

Electrochemical behaviour of steel in plain and blended cement concretes in sulphate and/or chloride environments

The electrochemical behaviour of reinforcing steel in plain and blended cement concrete specimens placed in sulphate, chloride and sulphate-chloride environments was investigated. The effect of cement composition and the exposure condition on the corrosion behaviour of reinforcing steel was evaluated by measuring corrosion potentials at periodic intervals and conducting potentio-dynamic scans after two and half years of exposure. The corrosion potential data indicated passive corrosion in plain and blended cement concrete specimens placed in the pure sulphate environment. The time to initiation of reinforcement corrosion, however, was higher in blended cements than plain cements in all chloride and chloride-sulphate environments. The concomitant presence of suphate and chloride salts did not significantly influence the time to corrosion initiation. The corrosion rate, however, was significantly influenced by the quantum of sulphate ions associated with the chloride salts. The superior performance of silica fume blended cement, in terms of longer time to corrosion initiation and lower corrosion rate, indicates its potential in enhancing the useful service life of reinforced concrete structures placed in the chloride-sulphate environments.

The electrochemical behaviour of steel under polarization in porous media simulating concrete

For simulating the corrosion of rebars in concrete, steel wire specimens were wrapped in porous polyvinyldiene fluoride sheets and placed in solutions corresponding to cement pore waters of various ages and possibly polluted with chlorides. The corrosion behaviour of steel was determined with potentiodynamic curves. For a given solution, peaks appear on these curves, at potentials which depend on the solution pH. The plots giving the peak potentials versus the solution pH include four straight parallel lines. The sizes of the pores influence these critical potentials because in small pores, the products formed at the metal-solution interface are not able to move freely.

Effect of ozonization and some additions on the corrosion and electrochemical behavior of steel 12Kh18N10T in sulfuric acid

The corrosion and electrochemical behavior of stainless steel in sulfuric acid media has been studied previously [i, 2]. The effect of ozone on the electrochemical behavior of a number of metals and steels in 2% and 70% sulfuric acid has also been studied [3, 4]. Data are given in the present communication for the effect of additions of benzimidazole (BIA) and manganese sulfate on the course of polarization curves for austenitic stainless steel 12KhI8NIOT in aerated and ozonized 20% H~SO~.

The Electrochemical Behavior of Steel Coated with Plasma Sprayed Coatings

The Electrochemical Behavior of Steel Coated with Plasma Sprayed Coatings

Corrosion and electrochemical behavior of steels and alloys in solutions containing fluorine and chlorine ions

Corrosion and electrochemical behavior of steels and alloys in solutions containing fluorine and chlorine ions

Electrochemical Behavior of Steel in Saturated Calcium Hydroxide Solution Containing Cl−, SO42−, and CO32−Ions

Abstract The effect of chloride, sulfate, and carbonate ions on the electrochemical behavior of steel in a simulated concrete environment has been studied using alternating current (AC) and direct ...

Corrosion and electrochemical behavior of steel in CO2 bearing water.

The corrosion mechanism of mild steel in CO2 bearing water has been studied by examining electrochemical behavior of carbonic substances, i.e., H2CO3 and HCO-3. These substances contribute to the cathodic reaction on the steel surface corroding in CO2 bearing waters. In the low pH region, the corrosion rate is controlled by the reduction rate of H2CO3 and is much higher than that in non-carbonic solutions of the same pH. In the high pH region, however, the corrosion rate is controlled by the stability of the FeCO3 film that forms on the steel surface.

Electrochemical Behavior of Steel in Concrete as a Result of Chloride Diffusion into Concrete: Part 2

Abstract Penetration of chloride salts into concrete from sources such as deicing-salts or sea water causes a severe corrosion problem to reinforcing steel. In this paper, the effect of salt penetration into concrete on the corrosion process was investigated by electrochemical techniques such as anodic and cathodic polarization. The potential measurements of steel in concrete were also made to compare the data with the results obtained from the polarization curves. Concretes made of Type I and Type V Portland cement were used. It was found that corrosion of steel in Type I Portland cement concrete is more rapid than in the Type V Portland cement concrete when the steel is exposed to salt solutions. This may be due to the differences in alkalinites which exist between the Types I and V Portland cement, whereas steel in the concrete with high pH can tolerate more Cl− than in concrete with lower pH. Corrosion of steel is more severe in the presence of chlorides added externally to hardened concrete than in the presence of chloride mixed with fresh concrete. Anodic and cathodic current densities for steel in concrete made of Types I and V Portland cement increase with the time that the concrete remains in the salt solutions.

Effect of Weathering on the Electrochemical Behaviour of Steels

AbstractThe potentiodynamcic anodic behaviour of some low-alloy steels was investigated in 0·1 M Na2SO4 in relation to weathering. The set of materials tested included an ordinary carbon steel, a Cu-bearing steel, a Cu-P steel and a Corten-type steel.The weathering was effected by short-duration exposures either in an industrial atmosphere or in a sulphate spray, and also by anodic dissolution through repeated potential sweeps. In every case the potentiodynamcic anodic behaviour clearly differentiated the steels, giving satisfactory correlation with the type and content of alloying elements, and was consistent with the weight-loss behaviour in extended atmospheric tests.

Electrochemical behaviour of steel in sodium hydroxide solution containing sodium chloride

Electrochemical behaviour of steel in sodium hydroxide solution containing sodium chloride

Electrochemical Behavior of Steel in Concrete

Electrochemical Behavior of Steel in Concrete