Corrosion Rate Measurements Research Articles

Further studies of in situ corrosion testing of miniature copper–cast iron nuclear waste canisters

To ensure the safe disposal of spent fuel in Sweden, SKB is planning to use the copper–iron canister in a granitic deep geological repository, surrounded by a compacted bentonite engineered barrier. In order to develop a deeper understanding of the internal corrosion behaviour of the design should a leak occur in the outer copper canister, a set of model canisters was set up in the Äspö underground laboratory in contact with bentonite with a range of densities. The environmental conditions and electrochemical corrosion behaviour were monitored using a range of techniques. Water analysis and electrochemical measurements indicated an increase in the corrosion rate of both iron and copper in contact with low density bentonite, and of iron only in experiments with no bentonite present. This behaviour may be attributable to microbial activity. The measured corrosion rate depends on the technique used and it will be necessary to confirm the measurements by removal and examination of weight loss coupons.

The Corrosion Resistance Properties and Precipitate of Common Artificial Reef Materials

The corrosion properties of several common artificial reef materials were studied using electrochemical methods and by measuring corrosion rates in estuary water and seawater. Experimental results show that the 6063 aluminum alloy can be a reef construction material only in low velocity estuary water. Copper in seawater has high corrosion potential and can be passivated, but the high velocity water will destroy the passivation film and decrease the corrosion resistance of copper. Copper is a suitable reef material in low flow seawater and estuary water. With low open potential, high anode current and extensive corrosion, Q235 steel is only suggested as artificial reef material if applying sacrificial anode protection. Pine block and granite are natural materials whose degradation products won’t harm the environment, but the pine block has short service life while granite has a minimal corrosion rate. PVC has small corrosion rate but leaches toxic substances after degradation, so it is not suitable for wide-ranging use.

Experiences with high temperature corrosion at straw‐firing power plants in Denmark

AbstractBy the end of 2009, there will be eight biomass and five biomass co‐firing plants in Denmark. Due to the steep increase of corrosion rate with respect to temperature in biomass plants, it is not viable to have similar steam data as fossil fuel plants. Thus for the newer plants, Maribo Sakskøbing, Avedøre 2 biomass boiler, Fyn 8 and Amager 1 (Fyn 8 and Amager 1 are under commissioning), the steam temperature of the final superheaters are approximately 540 °C and the steel type used is an 18–10 stainless steel, (TP347H). However there is still a need to monitor corrosion rates, and to collate data to enable better lifetime prediction of vulnerable components in straw‐firing plants since the corrosion rates are so much faster than in coal firing plants. Therefore, there are continued investigations in recently commissioned plants with test tubes installed into actual superheaters. In addition temperature is measured on the specific tube loops where there are test tube sections. Thus a corrosion rate can be coupled to a temperature histogram. This is important since although a superheater has a defined steam outlet temperature, there is variation in the tube bundle due to variations of heat flux from the flue gas. This paper will describe the corrosion investigations for tube sections removed from Maribo Sakskøbing and Avedøre 2 biomass boiler which have been exposed for up to 30 000 h. In addition to monitoring the corrosion rates of actual components, there is a need to measure corrosion rates at higher temperatures to assess if there is a possibility to increase the outlet temperature of the plant, thus making the plant more cost effective. For this purpose Avedøre 2 biomass boiler has a test superheater loop fabricated in TP347H FG (the same material as the final superheaters). Some results from this test superheater will also be described. Effects of flue gas temperature and flue gas direction on corrosion rates are also discussed.

Corrosion Behavior of Alumina Reinforced Aluminium (6063) Metal Matrix Composites

The influence of alumina volume percent and solution heat-treatment on the corrosion behaviour of Al (6063) composites and its monolithic alloy in salt water, basic and acidic environments is investigated. Al (6063) – Al 2O3 particulate composites containing 6, 9, 15, and 18 volume percent alumina were produced by adopting two step stir casting. Mass loss and corrosion rate measurements were utilized as criteria for evaluating the corrosion behaviour of the composites. It is observed that Al (6063) – Al 2O3 composites exhibited excellent corrosion resistance in NaCl medium than in the NaOH and H 2SO 4 media. The unreinforced alloy exhibited slightly superior corrosion resistance than the composites in NaCl and NaOH media but the composites had better corrosion resistance in H 2SO 4 medium. Furthermore, solution heat-treatment resulted in improved corrosion resistance for both the composites and the unreinforced alloy while the effect of volume percent alumina on corrosion resistance did not follow a consistent trend.

C205 玉形弁下流における流れ加速型腐食の評価 : 2.腐食速度の測定(OS6 流れ加速型腐食)

In this study, in order to evaluate the effects of flow field on corrosion rate due to flow accelerated corrosion (FAC), a corrosion rate downstream of the globe valve was measured using the electric resistance method. The valve module had a cage and it was sandwiched between the pipes which had the corrosion sensors. The diameter of these pipe was 50mm, and the temperature of water was controlled within ±1 at 150deg-C. In these measurements, we carried out the two series of measurement. In first series (Run1), we kept flow velocity condition at 4.24m/s. In second series (Run2), we changed flow velocity condition from 4.24 to 5.66m/s. In these results, the distributions of FAC rates downstream of the globe valve were asymmetrical to the center axis of the pipe, and the peak of FAC rate was at 2D downstream from the valve. Increasing the mean velocity from 4.24 to 5.66m/s during the test period, FAC rates of the upper sensor at 2D downstream was increased and the other sensors were not increased. Comparing the measured corrosion rate to the calculated wall shear stress, the distributions of these ratios of downstream / upstream from the valve agreed well.

Industrial Progress: New Energy-Efficient Absorbents for the CO<sub>2</sub> Separation from Natural Gas, Syngas and Flue Gas

The CO2 separation from natural gas, syngas or flue gas represents an important industrial field of applications. An economic and energy-efficient CO2 separation from these gas streams is a prerequisite for sustainable industry contributions to the megatrends resource efficiency and globalization of technologies. One way of reducing operational expenditure for these separation processes is the development of better performing CO2 absorbents. Although a number of absorbents for the separation of CO2 from process gas streams exist, the need for the development of CO2 absorbents with an improved absorption performance, less corrosion and foaming, no nitrosamine formation, lower energy requirement and therefore less operational expenditure remains. Recent industrial activities have led to the development of novel high-performance CO2 scrubbing agents that can be employed in numerous industrial processes such as natural gas treatment, purification of syngas and the scrubbing of flue gas. The objective of this paper is to introduce these new high-performance scrubbing agents and to compare their performance with other state-of-the-art absorbents. It turned out, that the evaluated absorbents offer high cyclic capacities in the range of 2.4 to 2.6 mol CO2/kg absorbent and low absorption enthalpies (–30 kJ/mol) allowing for distinctive savings in the regeneration energy of the absorbent. Calculations with the modified Kremser model resulted in a reduction of the specific reboiler heat duty of 55%. Furthermore, the absorbents are less corrosive than standard amines as indicated by the measured corrosion rates of 0.21 mm/y versus 1.18 mm/y for a piperazine/methyldiethanolamine mixture. Based on new experimental results it is shown how substantial savings in operational and capital expenditure can be realized due to favorable absorbent properties. The novel high-performance CO2 system solutions meet recent industrial absorbent requirements and allow for more efficient or new CO2 separation processes.

Rebar corrosion in chloride environment

Chloride induced reinforcement corrosion in concrete is a serious durability problem. Different sources of chloride, i.e. chloride introduced at the fresh stage of concrete (i.e. internal chloride) and chloride entered during the hardened state (i.e. external chloride) may affect the performance of concrete in different ways. For the performance evaluation of reinforced concrete in chloride environment (i.e. both internal and external chloride), there is a need for performing different electrochemical tests to obtain various corrosion parameters that will specify the possibility and the magnitude of corrosion in concrete. In the present study, the results of an experimental investigation that includes different corrosion tests namely potential measurement, corrosion rate measurement and potentiodynamic polarization test have been presented and analyzed to evaluate the performance of concrete both in internal chloride and external chloride exposure conditions. In addition an attempt is made to correlate the corrosion parameters obtained from internal and external chloride exposure conditions. From the results it was observed that, dropped half-cell potential value obtained from external chloride exposure mostly lie in the active zone obtained from internal chloride exposure. In addition it was observed that there was significant difference in corrosion current values obtained from both internal and external chloride exposure conditions. Further on the basis of overall ranking obtained from the results of critical parameters from different exposure conditions, the performance of different cement–steel combinations against chloride induced rebar corrosion has been evaluated.

Studies of the corrosion inhibition of copper in sodium chloride solutions using chemical and electrochemical measurements

The inhibiting effects of 2-mercapto-4-amino-5-nitroso-6-hydroxy pyrimidine (MAP) at various concentrations on the copper corrosion in 3.5% NaCl solutions at 25 °C are examined. The inhibiting efficiency of MAP is evaluated from weight loss, potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), and electrochemical frequency modulation (EFM) measurements. Experimental investigations showed that MAP reduces markedly the copper corrosion in 3.5% NaCl solutions, and this reduction in corrosion rates enhances with increasing concentration of this compound. The results obtained from the different corrosion evaluation techniques are in good agreement. Polarization curves indicate that MAP is a mixed-type inhibitor. The results of EIS indicate that the value of CPEs tends to decrease and both charge transfer resistance and inhibition efficiency tend to increase by increasing the inhibitor concentration. EFM can be used as a rapid and non-destructive technique for corrosion rate measurements without prior knowledge of Tafel constants.

Internal Current Effects on Localized Corrosion Rate Measurements Using Coupled Multielectrode Array Sensors

Abstract Coupled multielectrode array sensors (CMAS) have been used for real-time monitoring of corrosion, particularly localized corrosion. The internal anodic current on the most anodic electrode...

Measuring the corrosion rate of steel in concrete – effect of measurement technique, polarisation time and current

AbstractBoth on‐site investigations and laboratory studies have shown that different corrosion rates are obtained when different commercially available corrosion rate instruments are used. The different electrochemical techniques and the measurement parameters used, i.e. polarisation current and time, are in some studies considered the main reasons for the variations. This paper presents an experimental study on the quantitative effect of polarisation time and current on the measured polarisation resistance – and thus the corrosion current density – of passively and actively corroding steel. Two electrochemical techniques often used in instruments for on‐site corrosion rate measurements are investigated. On passively corroding reinforcement the measured polarisation resistance was for both techniques found to be highly affected by the polarisation time and current and no plateaus at either short or long polarisation times, or low or high polarisation currents were identified. On actively corroding reinforcement a large effect of the polarisation time was also found, but only a minor effect of the polarisation current. The effect of the polarisation time was, however, practically independent of the corrosion rate for actively corroding steel. For both techniques guidelines for polarisation times and currents are given for (on‐site) non‐destructive corrosion rate measurements on reinforcement steel in concrete.

Effect of concrete carbonation process on the passivating products of galvanized steel reinforcements

AbstractThe composition of passivating products on galvanized steel reinforcement in concrete during carbonation was studied. Cube‐shaped concrete specimens were manufactured with Portland 52.5 R cement and reinforced with hot‐dip galvanized steel sheets obtained from pure Zn and ZnSnBiNi alloy bath. The concrete specimens were exposed to air curing for 28 days and then to the carbonation chamber. Corrosion rate and potential measurements were performed both during the curing in air and exposure in a carbonation chamber. At defined periods of time, some concrete specimens were broken and the galvanized steel sheets were submitted to XRD, SEM observations and EDX analysis. The growth of the passivation products was evaluated by integrating the diffraction peaks. XRD analysis and SEM observations show that the layer of calcium hydroxyzincate (CaHZn), formed on the galvanized sheets during the air curing, is destroyed by the concrete carbonation process. However, potential measurements indicate that the galvanized steel always remains in the passive state. X‐ray diffractometry was not able to identify the new passivating product; EDX maps suggest the presence of zinc carbonates.

ChemInform Abstract: The Effect of pH on the Corrosion of Nuclear Fuel (UO2) in Oxygenated Solutions,

Abstract The oxidative dissolution of UO2 has been studied in NaClO4 and Na2SO4 solutions as a function of pH over a range of 0.8 ⩽ pH ⩽ 12 using a combination of electrochemical and X-ray photoelectron spectroscopic techniques. The relative stability and solubility of solid uranium oxides and uranium speciation in aqueous solutions were examined using thermodynamic calculations. In neutral to alkaline solutions (pH ≥5), dissolution is preceded by the growth of a thin film of UO2 33 on the UO2 surface. This film achieves a steady-state thickness (∼6 nm) in 5 to 10 h, and the thickness increases with an increase in pH. Over the next 10 to 100 h, further oxidation to a hydrated form of UO3 occurs, after which steady-state dissolution conditions are achieved. Formation of UO3 · xH2O is a precursor to dissolution and its presence appears to be confined mainly to the grain boundaries. In acidic solutions UO2.33 formation does not occur. Oxidation proceeds directly to the UVI state (possibly to UO3 · xH2O) and the dissolution rate, measured by extrapolation of steady-state currents to the corrosion potential, is approximately 50 times greater at pH = 2.5 than it is at pH = 9.7. The electrochemically measured corrosion rate value of ∼45 × 10−8 g cm−2 d−1 at pH = 2.5 compares well with the value of ∼ 25 × 10−8 g cm−2d−1 measured chemically by Thomas and Till. The dependence of the steady-state corrosion potentials on pH suggests possible rate control by the anodic dissolution reaction for pH > 10. For pH values between 2 and 10, the corrosion potential varies only slightly with pH, and it is unclear whether the anodic or cathodic reaction is rate-controlling in this region.

Monitoring Copper and Silver Corrosion in Different Museum Environments by Electrical Resistance Measurement

The results are reported of a systematic programme of electrical resistance measurement (ERM) of copper and silver corrosion rates within various museum environments, directed towards developing preventive conservation understanding and practice. Electrical resistivity measurements were made using copper and silver probes for one month and one year in 33 locations, and these are interpreted in comparison with two standards. Advantages and drawbacks of different methods available for the evaluation of the corrosion aggressiveness of indoor air are discussed. Practical solutions are proposed for improving the protection of metal objects collections. Improvements are also proposed to maximize the efficiency and suitability of the measuring device to the very specific applications of cultural heritage collections.

Inhibition of copper corrosion in 3.5% NaCl solutions by a new pyrimidine derivative: electrochemical and computer simulation techniques

A new pyrimidine heterocyclic derivative, namely 2-ethylthio-4-(p-methoxyphenyl)-6-oxo-1,6-dihydropyrimidine-5-carbonitrile (EPD) was prepared and its inhibition performance towards copper corrosion in 3.5% NaCl solutions was studied by potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) and electrochemical frequency modulation (EFM) measurements. Experimental investigations showed that EPD reduces markedly the copper corrosion in 3.5% NaCl solutions. EFM can be used as a rapid and non destructive technique for corrosion rate measurements without prior knowledge of Tafel constants. Monte Carlo simulation technique incorporating molecular mechanics and molecular dynamics can be used to simulate the adsorption of pyrimidine derivative (EPD) on the Cu (111) surface in 3.5% NaCl.

Cultural evolutionary design of adaptive wavelet filters based on lifting scheme for micro-instruments

An evolutionary procedure based on cultural algorithms for the optimal design of adaptive wavelet filters based on lifting scheme is proposed. Numerical results of characterization, based on statistical experiment design, as well as validation, based on the comparison with a genetic optimization algorithm, are presented. Experimental results of the validation on two case studies for reducing uncertainty arising from noise in on-field corrosion rate measurements are highlighted.

Anodic behaviour of supermartensitic stainless steel weldments

The corrosion resistance evaluation was carried out in a supermartensitic stainless steel weldment through anodic polarisation curves and through corrosion rate measurements in an acidic medium. The electrochemical measurements were carried out separately in the base metal samples, the heat affected zone and the weld metal of electron beam weldments. An improvement was found in the corrosion resistance from the base metal to the weld metal.

Selection and evaluation of a new Pu density measurement fluid

This paper summarizes efforts leading to selection of a new fluid for the determination of the density of large Pu parts. Based on an extended literature search, perfluorotributylamine (CF3(CF2)3)3N, trade name FC-43) was chosen for an experimental study. Plutonium coupon corrosion studies were performed by exposing Pu to deaerated and aerated solutions and measuring corrosion rates gravimetrically. Samples of deaerated and aerated (FC-43) were also irradiated with 60Co gamma rays. The samples were extracted with NaOH and analyzed by Ion Chromatography (IC). In surface study experiments, Pu coupons were exposed to deaerated and aerated solutions of FC-43 and analyzed by X-ray photoelectron spectroscopy (XPS). The XPS data indicate that there is no detectable surface effect caused by the new fluid.

Field Test of High-Temperature Corrosion Sensors in a Waste-to-Energy Plant

Abstract Electrochemical probes originally designed for use in aqueous environments were shown to measure corrosion rates in a high-temperature gaseous environment where electrolyte consisted of conductive ashes and liquid slag. The field trial of the probes was conducted over a five-month period to monitor fireside corrosion in a waste-to-energy (WTE) plant. The three-electrode air-cooled corrosion sensors, each including a thermocouple to monitor sensor temperature, were installed in four different ports at approximately the same level of the WTE boiler. A total of 12 sensors were tested: six with electrodes using the carbon steel boiler tube material and six using the nickel-chromium alloy used for weld overlays for the electrodes. Corrosion rates and temperatures of the sensors were monitored continuously throughout the trial. Metallographic measurements of sensor thickness loss were used to calibrate the electrochemical corrosion rates. Air cooling of the sensors was found to be necessary to bring th...

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.

Suitability of Various Measurement Techniques for Assessing Corrosion in Cracked Concrete

A critical evaluation of results from three corrosion assessment methods used in an experimental study to investigate the influence of cracks on the rate of chloride-induced corrosion is presented in this article. The objective was to determine the suitability and reliability of the corrosion assessment methods for application in cracked concrete. Beam specimens (100 x 100 x 500 mm [3.9 x 3.9 x 19.7 in.]) with crack widths of 0.7 and 0.4 mm (0.028 and 0.016 in.), as well as incipient cracks, were made using two binder types (100% CEM I ordinary portland cement [OPC]) and 50/50 OPC/ slag blend), two water-binder ratios (w/b) (0.40 and 0.55) and a constant cover of 40 mm (1.6 in.) to steel reinforcing. The specimens were subjected to repeated cycles of 3-day wetting with 5% NaCl, and 4-day air drying for 32 weeks. Half-cell potential (HCP), resistivity (Wenner probe), and corrosion rate (coulostatic) measurements were taken at the end of each 3-day wetting period. Chloride conductivity tests were also performed on companion cube specimens at 28 and 90 days. No significant differences in resistivity values were noted between cracked and uncracked specimens, despite the fact that the corrosion rate increased with increasing crack width. The insensitivity of resistivity measurements to the presence of cracks was attributed to the fact that measurements were taken after every 3-day wetting period, when the specimens would have been saturated with salt solution. The chloride conductivity and resistivity measurements gave a similar indication of the corrosion rates. HCP and corrosion rate measurements showed a good correlation, and they gave a clear indication of corrosion in cracked reinforced concrete (RC) specimens, although for practical applications, HCP measurements need to be complemented with other corrosion assessment techniques. For the resistivity assessment technique—in addition to concrete quality and magnitude of resistivity—correction factors are required to relate the resistivity of uncracked concrete to corrosion characteristics of cracked concrete. A methodology for the application of correction factors is proposed.