Determination Of Corrosion Rate Research Articles

Microbially Induced Corrosion Rate Determination Applying Clark Amperometric Sensor

Microbially Induced Corrosion Rate Determination Applying Clark Amperometric Sensor

Aspects of the corrosion of refractories in structured aggressive media

This article examines aspects of the testing of refractories for corrosion resistance by different methods. Studies were made of the corrosion resistance of refractories under dynamic conditions by using a special unit based on rotation of the test specimen in a melt of the corrodent (boron-bearing ultrahard flint, 65% PbO, 35% B2O3). It was determined that corrosion rate increases in proportion to the depth of immersion of the specimen in the melt. Anew method is proposed for determining corrosion rate, the method making it possible to significantly shorten corrosion tests and improve the accuracy of the results.

Influence of Heat Treatments on the Corrosion Resistance of Medium -Carbon Steel using Sulfuric Spring Water

The corrosion is one of the important problems that may be occur to the parts of machinery and equipment after manufactured and when used as a result of exposure to corrosive media. Plain-carbon steel is considered as one of the most common minerals used in industrial applications. Some of heat treatments can have direct effect on the corrosion rate of steel by building up galvanic corrosion cells between its microscopic phases. Therefore, to adopt one of kinds of the plain-carbon steel and the most commonly used in industry to be study subject, that is medium carbon steel and took samples of this steel has been treated thermally in three methods which the normalising, annealing, and hardening .The corrosive media used in the research is Sulfuric Spring, it contains many chemical compounds to show its influence on the corrosion of steel. The weight loss method is used to determine corrosion rate and to compare between the results obtained, show that the greatest corrosion resistance of the annealed steel and the corrosion resistance of the hardened steel is the lowest while the corrosion resistance of the normalised steel is in-between them. Calcium carbonate was formed on the metal surface which acts as an isolating layer which decrease corrosion rate with time.

Corrosion inhibitors from expired drugs

This paper presents a method of expired or unused drugs valorization as corrosion inhibitors for metals in various media. Cyclic voltammograms were drawn on platinum in order to assess the stability of pharmaceutically active substances from drugs at the metal–corrosive environment interface. Tafel slope method was used to determine corrosion rates of steel in the absence and presence of inhibitors. Expired Carbamazepine and Paracetamol tablets were used to obtain corrosion inhibitors. For the former, the corrosion inhibition of carbon steel in 0.1molL−1 sulfuric acid solution was about 90%, whereas for the latter, the corrosion inhibition efficiency of the same material in the 0.25molL−1 acetic acid–0.25molL−1 sodium acetate buffer solution was about 85%.

Electrochemical study of the corrosion rate of carbon steel in soil: Evolution with time and determination of residual corrosion rates under cathodic protection

Steel coupons were buried in soil boxes for 2.5months, with or without cathodic protection. A soil from the field was used and moistened by demineralized water or 5gL−1 Na2SO4 solution. Instantaneous corrosion rates were deduced from voltammetry experiments while average values were obtained by weight loss measurements. A detailed analysis of the polarization curves led to an estimation of residual corrosion rates (τrc) of coupons under cathodic protection. This residual phenomenon could be followed with time and it was observed that τrc decreased down to ∼10μmyr−1. Cathodic protection could be optimised with this methodology.

Determination of Mild Steel Corrosion Rate under Turbulent Flow in Highly Acidic Solution

Determination of Mild Steel Corrosion Rate under Turbulent Flow in Highly Acidic Solution

Electrochemical behavior of Ni 3Al-based intermetallic alloys in NaOH

The corrosion behavior of Ni 3Al-based intermetallic alloys in a 0.5 M NaOH solution was studied at 25 °C. The open circuit potential, cathodic and anodic potentiodynamic polarization, Tafel plots and linear polarization resistance measurements were used to characterize the corrosion behavior. For the Ni 3Al(B, Zr) alloy, potentiodynamic polarization curves showed a wide passive region that can be found between about −0.220 V SCE and 0.520 V SCE. On the other hand, a narrow passive region, in the range of potentials from about −0.180 V SCE to 0.180 V SCE, was observed for the Ni 3Al(B, Zr, Cr, Mo) alloy. Chromium, as an alloying element in the Ni 3Al(B, Zr, Cr, Mo) alloy, contributes to transpassive dissolution of the passive film at much lower anodic potentials and remarkably reduces the passivation region. The experiments indicated also that damaged passive films on alloys repairs itself and pits do not initiate. The surface of both alloys and passive films possess extremely high corrosion resistance in a studied solution. However, Tafel and linear polarization tests revealed that freshly exposed surfaces of the Ni 3Al(B, Zr) alloy exhibited better corrosion resistances than the Ni 3Al(B, Zr, Cr, Mo) alloy. Both methods, used for the determination of corrosion rates gave very similar results. The calculated corrosion rates are about 2.8 ·10 −3 and 6.0·10 −3 mm year −1 for the Ni 3Al(B, Zr) alloy and B, respectively.

Corrosion inhibition of copper in HNO3 solution using thiophene and its derivatives

The corrosion behavior of copper in the presence of thiophene (T) and some of its derivatives [2-thiophene carboxylic acid (TC) and 2-thienyl ethanol (TE)] has been investigated in 2M HNO3 solution using electrochemical frequency modulation (EFM), electrochemical impedance spectroscopy (EIS), potentiodynamic polarization and weight loss techniques. Polarization studies showed that these compounds act as mixed type inhibitors. EFM technique provides a new tool for electrochemical corrosion monitoring and was used as an effective method for corrosion rate determination. In EFM measurements corrosion current density was determined without prior knowledge of Tafel slopes. Inhibition efficiency of these compounds has been found to vary with concentrations of the compounds and temperature. The adsorption of these compounds on the copper surface from the acid solution has been found to obey Langmuir adsorption isotherm. The thermodynamic activation parameters of copper corrosion in 2M HNO3 were determined and discussed. The results obtained from EFM, EIS, Tafel and weight loss measurements were in good agreement.

Condition assessment of concrete structures at nuclear power plants by state of the art non-destructive testing

The approach combining Non Destructive Examination (NDE) with Finite Element Analysis (FEA) methods is both workable and necessary in order to accurately determine and predict the condition of Nuclear Power Plant (NPP) containment structures. This approach was introduced in the European 5th Framework Project with acronym CONMOD [1]. The current paper presents some of the work performed after the CONMOD project combining the on-site investigation at nuclear power plant (NPP) stations in Sweden and Finland. Several non-destructive techniques were chosen for the investigations described in this paper. The MASW (Multi Channel Analysis of Surface Waves) and Impact Echo (IE) techniques have been used for evaluation of thickness and stiffness of concrete and also for location of possible defects. The above-mentioned techniques have been applied under investigations of concrete containments. Additionally reinforcement corrosion was investigated in cooling water channels by means of the Galvanostatic Pulse technique allowing determination of corrosion rate. Further, following the CONMOD concept, the coupling between the non-destructive measurements on site and finite element method is established. As the result of this coupling, the information about the status of concrete structures in nuclear power plants is obtained. In the ongoing research & development project CONSAFESYS (Concrete Containment Condition Status & Ageing Examination System) the qualification and validation of investigative methods and diagnostic tools and analysis for reactor containments are further developed. One unique benefit with the CONSAFESYS project is the possibility of introducing artificial defects and anomalies into a decommissioned reactor containment structure.

Inhibition of Mild Copper Metal Corrosion in HNO3 Medium by Acid Extract of Azadirachta Indica Seed

Efficiency of acid extract of dry azadirachta indica seed as corrosion inhibitor for mild copper metal in various concentration of (1 N,2 N and 3N) HNO3 medium was investigated in the present study. Experimental methods include weight loss, determination of corrosion rate, inhibition efficiency and phytochemical analysis was studied. The results indicate azadirachta indica seed to be a good corrosion inhibitor of a mixed type and having efficiency as high as 95% at 1% inhibitor concentration in different time duration.

Study of alloy V91 of the system Al – Zn – Mg – Cu system supercooled solid solution decomposition

Isothermal and thermokinetic diagrams are worked out for the decomposition of supersaturated solid solution of for heat treated alloy V91 of the Al – Zn – Mg – Cu system. Curves for these diagrams correspond to the start of forming GP zones, metastable T′ and stable phases (T, η). An isothermal diagram for the alloy is plotted from the results of hardness and corrosion rate determination. Critical cooling rates are determined for alloy V91 from the diagrams obtained.

Electrochemical techniques for determining corrosion rate of rusted steel in seawater

Corrosion rates of mild steel for long-term immersion were estimated by electrochemical and weight-loss methods. The results showed that application of electrochemical methods yielded erroneous values. The main reason was that, β-FeOOH, produced after long-term immersion with high electrochemical activity in the inner rust layer, exerted significant influence. In electrochemical tests, even small polarization can make β-FeOOH participate in cathodic reaction, which leads to overestimating corrosion rate. In order to confirm it, electrochemical behaviour was studied in aerated and deaerated conditions to investigate the effect of rust layers on reduction reaction. After calibration, the electrochemical measurement result was coincided with the weight loss.

Potentiostatic transient technique, a simple approach to estimate the corrosion current density and Stern–Geary constant of reinforcing steel in concrete

The linear polarization resistance (LPR) method, introduced by Stern and Geary, is widely used in determining corrosion rates of steel bars in concrete or synthetic pore solution. The major limitation of this method is that the value of the Tafel slopes, and consequently the Stern–Geary constant (B), is necessary for accurate calculation of the corrosion rate. This paper proposes a simple method for determining the corrosion current density and the Stern–Geary constant, using the results of the potentiostatic transient technique. The effect of the Stern–Geary constant on the corrosion rate of steel bar in concrete is also discussed. Results of this study show that potentiostatic transient method can be used successfully to determine the corrosion rate of steel bars in concrete without using the pre-assumed value of B.

Metal Corrosion Rate Determination of Different Solutions and Reinforced Concrete Specimens by Means of a Noncontacting Corrosion Method

Abstract All the current techniques used to measure the metallic corrosion require contact with the metal. Particularly, in the case of reinforcement corrosion, this signifies the need to reach the...

A study of the inhibition of iron corrosion in HCl solutions by some amino acids

The performance of three selected amino acids, namely alanine (Ala), cysteine (Cys) and S-methyl cysteine (S-MCys) as safe corrosion inhibitors for iron in aerated stagnant 1.0 M HCl solutions was evaluated by Tafel polarization and impedance measurements. Results indicate that Ala acts mainly as a cathodic inhibitor, while Cys and S-MCys function as mixed-type inhibitors. Cys, which contains a mercapto group in its molecular structure, was the most effective among the inhibitors tested, while Ala was less effective than S-MCys. The low inhibition efficiency recorded for S-MCys compared with that of Cys was attributed to steric effects caused by the substituent methyl on the mercapto group. Electrochemical frequency modulation (EFM) technique and inductively coupled plasma atomic emission spectrometry (ICP-AES), were also applied to make accurate determination of corrosion rates. Validation of the Tafel extrapolation method for measuring corrosion rates was tested. Rates of corrosion rates (in μm y −1) obtained from Tafel extrapolation method are in good agreement with those measured using EFM and ICP methods. Some theoretical studies, including molecular dynamics (MD) and density functional theory (DFT), were also employed to establish the correlation between the structure (molecular and electronic) of the three tested inhibitors and the inhibition efficiency. Adsorption via hydrogen bonding was discussed here based on some theoretical studies. Experimental and theoretical results were in good agreement.

A Study on the Accuracy of the Tafel Extrapolation Method in HCl

Accuracy and validity of the Tafel extrapolation method for determining corrosion rates of carbon steel in 1,2 and 3M HCl solutions open to air is discussed. Corrosion rates obtained from polarization experiments were compared with that of weight loss method. For analysing data obtained from polarization experiments electrochemical impedance spectroscopy (EIS) measurements were performed before polarization experiments. The results showed that formation of a corrosion product film and increasing the polarization resistance (Rp) of this film with time cause the corrosion rates obtained from Tafel extrapolation tend to be higher than corrosion rates obtained from weight loss test.

Validation of Modeling Tools to Describe the Corrosion/Precipitation Behavior of Eurofer Steel in Flowing Pb-17Li

RAFM steels (e.g. Eurofer) are considered as struc-tural material for blanket components of future fusion power plants. One of the envisaged blanket concepts to be tested in ITER foresees the application of a liquid breed-er, the eutectic lead alloy Pb-17Li. Various corrosion experiments have been made in the past, mostly conducted up to temperatures of ca. 480°C, with respect to deter-mine corrosion rates and mechanisms and comparison of the results with earlier tested RAFM-steels of type F82H-mod., Optifer and Manet. In the mean time the envisaged operational temperature increased to around 550°C and flow rates may also have changed. Thus extrapolations of the RAFM-steel corrosion behavior determined in the past to the higher working conditions may be problematic due to large uncertainties in reliability and, additionally, only low knowledge on transport of dissolved components in the Pb-17Li flow is present.Therefore, the development of modeling tools for de-scribing Pb-17Li corrosion was of absolute necessity. The modular structured code MATLIM is based on physical, chemical and thermo-hydraulic parameters and, in the first stage, the development was focused on the dissolution of Eurofer steel and validation with test results ob-tained at 480 and 550°C in the lead-lithium loop PICOLO of FZK.

Corrosion of overlay weld cladding in waterwalls of waste fired CFB boiler

Candidate materials for weld overlay coating of waterwalls have been investigated to determine corrosion rates and investigate corrosion mechanisms. Test waterwall panels with single layer weld overlays were exposed for a total of 7727 h in a 75 MWtot circulating fluidised bed boiler with 470°C/65 bar steam data. The fuel was 60% industrial waste and 40% household waste, resulting in very corrosive conditions. Six weld overlay materials were tested: the well proven alloy 625, a modified alloy 625 in which niobium was replaced by tungsten, alloy 59, alloy 22, a cheaper nickel base alloy 650 which contains some iron and a 310 grade stainless steel. Significant material loss occurred for all the panels. The nickel base alloys mainly developed hemispherical pits while the stainless steel exhibited relatively uniform corrosion. This means that the progress of the corrosion process is easier to monitor by inspection for the stainless steel. Detailed analyses of the corrosion products showed that conditions were sufficiently oxidising to allow formation of metal oxides, but that there were also extensive deposits of alkali and heavy metal chlorides. The corrosion mechanism is discussed in terms of formation of a molten salt layer which dissolves the oxide layer by fluxing.

Investigating accuracy of the Tafel extrapolation method in HCl solutions

This paper discusses the validity and accuracy of the Tafel extrapolation method for determining corrosion rates of carbon steel in 1, 2 and 3 M HCl solutions open to air. Corrosion rates obtained from polarization experiments were compared with that of weight loss method. For analysing data obtained from polarization experiments electrochemical impedance spectroscopy (EIS) measurements were performed before polarization experiments. The results showed that formation of a corrosion product film and increasing the polarization resistance ( R p) of this film with time cause the corrosion rates obtained from Tafel extrapolation tend to be higher than corrosion rates obtained from weight loss test.

Determination of the long-term intergranular corrosion rate of stainless steel in concentrated nitric acid

Stainless steels with low carbon content and free from any precipitation undergo intergranular attack in hot nitric acid. The corrosion rate measured by weight loss requires prolonged immersion testing to reach the apparent steady state corrosion, which coincides with the onset of grain dropping. A more appropriate method for predicting the long-term penetration rate is described in this study. A close observation and a statistical analysis of the attack grooves were firstly undertaken using immersion testing. The major findings are an outstanding morphology of the grooves with flat planes and preserved angle even after the onset of grain dropping, as well as a constant rate of the penetration into the surface. The formation of the grooves could then be represented by a geometrical model put forward by Beaunier and co-workers. Consequently, the method proposed for predicting the penetration rate consists in measuring the depth and the angle of the grooves obtained in short time immersion testing. Multiplying the penetration rate calculated from the previous data by the ratio between the penetration depth and the length of the grain boundary path does give an accurate long-term penetration rate. The method has been shown to apply successfully to AISI 304L stainless steel in several nitric solutions.