Veränderung der Korrosivität der Atmosphäre gegenüber metallischen Werkstoffen auf dem Gebiet der neuen Bundesländer seit 1989

Changes of the corrosivity of the atmosphere against metallic materials on the territory of the new federal countries of FRG since 1989 The results of long-time examinations of the corrosivity of the atmosphere demonstrated that in the period from 1979 to 1989 on the territory of the formerly GDR no changes could be established. The comparison of these results with those obtained at the same territory in the period from 1989 to 1994 shows a significant decrease of corrosivity against metallic materials which is caused by a lower deposition rate of the corrosion pollutant SO₂. This positive development can be explained by an improvement of the situation of immission which occurs in sequence of changes of the industrial structure as well as by active measures of environmental protection in the new countries of FRG after the political changes in the year 1989.     

Long-term forecast of corrosion mass losses of technically important metals in various world regions using a power function

An analysis of the results of corrosion tests on flat and helix specimens made of technically important metals carried out within the ISO CORRAG program is given. Stochastic relationships between coefficient n in the power function, which characterizes the protective properties of the corrosion products, and the limiting corrosion rate α, with the corrosivity of each type of atmosphere were found. A forecast of corrosion losses for a period of up to 50 years was given using the linear function in the stationary stage, a power function, and limiting corrosion rate values α. The reliability of the forecasts was estimated.     

Atmospheric corrosion in Mauritius

Abstract

Carbon steel is commonly used in Mauritius, and information related to its atmospheric corrosion behaviour in the Mauritian atmosphere is not readily available. Hence, the present study was performed to obtain relevant data and to develop a model for predicting the atmospheric corrosion degradation of carbon steel in Mauritius. Carbon steel samples were exposed outdoors at several sites, according to BS EN ISO 8565. They were removed after specific time periods, and their mass loss was determined. At the same time, the sites’ environmental parameters were monitored. From the mass loss measurements and the environmental parameters considered, it was found that the corrosivity of the Mauritian atmosphere falls in category C3 to C4, according to ISO 9223. A model was developed using the SPSS software, and it was found that the atmospheric corrosion in Mauritius depends mainly on the time of exposure and the carbon content of carbon steel.     

Estimating and Mapping the Material Corrosion Losses in the European Part of Russia with Unified Doze—Response Functions

The unified doze—response functions (DRF) obtained according to the European Materials Exposure Program (EMEP) of the UN European Committee of Economics and describing the effect of acidic precipitates on materials are used for estimating the corrosion rates of metals, glass, and stones and the service lifetimes of alkyd-melamine coatings in the European part of Russia (EPR). The climate zones from cold (the Arctic) to subtropical (the Black Sea coast) including the areas with the heightened SO₂ levels are covered. In the EMEP scale (150 × 150 km), the maps of the average annual temperature (T), relative air humidity (Rh), estimated time of wetness (TOW), annual amount of precipitates (Rain), wet deposits (Rain · H⁺), and ozone level are shown. The TOW parameter is determined both by T and Rhfactors, although in the cold and northeast region, T produces the predominant effect. The maps of the corrosion rates of structural materials and alloys, the erosion of limestone and sandstone for ten years, and the service lifetimes of galvanized painted steel are considered. The effect of all the atmospheric factors, the scale and prospects of mapping the territory of Russia, the classification of the atmosphere corrosivity, and other aspects are discussed. The results indicate that the DRFs constructed can be used for mapping and estimating the cost of corrosion losses in cold regions even when the cold places are not directly involved in the test program. The effect of SO₂ on the corrosion is especially pronounced within the temperature zone of 9 to 11°C, which crosses the whole Europe and is characterized by the admissible pollution levels lower than in colder zones.     

Long‐term atmospheric corrosion monitoring

The paper presents the analysis of corrosion rates of carbon steel, zinc, aluminium and copper after long‐term exposition as a function of time and environmental parameters. All experimental methodologies on the test sites were carried out according to ISO standards. The analysis of trends of environmental pollution and corrosion rates was performed for one year exposition of metals on three sites (urban/industrial, urban and rural atmosphere) in Poland. The corrosivity changes as a result of a reduction of corrosion rates of metals used are relatively smaller then the reduction of pollution. By using the equation C = Atⁿ, where C – corrosion rate after t years, A – corrosion rate after the first year of exposition, and results of long‐term corrosion rates, exponent n was determined for the different metals and sites from log‐log plots.     

Physicochemical studies of mild steel corrosion and atmospheric corrosivity mapping of Karachi: An important harbor city of modern Maritime Silk Route

This paper has reported physicochemical features of mild steel's corrosion products and provided atmospheric corrosivity maps of Karachi harbor city, drafted on the basis of spatial distribution of corrosion data from July 2018 to June 2019 at 10 different urban, industrial, and marine test sites. Exposure tests have been performed to study atmospheric corrosivity, corrosion products, and corrodants including chloride, sulfur dioxide, time of wetness (TOW), and corrosion rate as per ISO and ASTM standards. Scanning electron microscope, Fourier-transform infrared spectroscopy, and X-ray diffraction have corroborated the presence of lepidocrocite, goethite, magnetite, and quartz phases at almost all the test sites, with slight variations in their morphologies and quantities. The data analysis has revealed that TOW is a major detrimental factor to accelerate corrosion of mild steel at Karachi city. The corrosivity category of all urban and marine test sites is found in C₄–C₅ range, whereas for industrial test sites, it is found in C₃–C₅ range. Resultant corrosivity maps have shown that the prevailing atmosphere is significantly corrosive at Karachi harbor city. This study has furnished a novel product of atmospheric corrosivity map, which is the first-ever corrosivity map for Pakistan.     

Electrochemical Corrosion Investigations on Anaerobic Treated Distillery Effluent

Present study is focused on the corrosivity of anaerobic treated distillery effluent and corrosion performance of mild steel and stainless steels. Accordingly, electrochemical polarization tests were performed in both treated distillery and synthetic effluents. Polarization tests were also performed in synthetic solutions and it was observed that Cl^? and K⁺ increase whereas SO₄ ^?, PO₄ ^?, NO₃ ^?, and NO₂ ^? decrease the corrosivity of effluent at alkaline pH. Further, comparison in corrosivity of distillery and synthetic effluents shows the former to be less corrosive and this is assigned due to the presence of amino acids and melanoidins. Mild steel experienced to have the highest corrosion rate followed by stainless steels—304L and 316L and lowest in case of SAF 2205. Relative corrosion resistance of stainless steels is observed to depend upon Cr, Mo, and N content.     

Statistical approaches for assessment of water corrosivity

Abstract

This paper investigated the effects of eight dissolved species concentrations on corrosion of carbon steel in water. Short term electrochemical experimental measurements indicated that the corrosion mechanisms of carbon steel in brackish water are uniform and pitting corrosion. The corrosivity of water is difficult to be defined using single parameter such as the corrosion rate. In this case, Mahalanobis–Taguchi method, as a discriminant analysis approach, is applicable for water corrosivity assessment. Mahalanobis–Taguchi method enables to predict whether a given water sample is acceptably corrosive or not. The preliminary investigation has indicated that Mahalanobis–Taguchi method can serve as a tool for water corrosity assessment.     

Behaviour of Antifreeze Solutions in a Simulated Aluminium Alloy Engine Test Rig

Abstract

Tests have been carried out in an antifreeze test rig to investigate the corrosion resistance of aluminium alloys to antifreeze solutions conforming to B.S. 3150 and B.S. 3151. The results have shown that both antifreeze solutions have a similar corrosivity towards aluminium alloys and that, in general, these rates are low. The shape and the position of the specimen in the test rig determined the amount of corrosion. Pitting attack occurred on flat specimens in virtually stagnant conditions, whilst very little corrosion occurred on specimens immersed in a high rate of coolant flow.     

Atmospheric corrosion in two different urban environments in Portugal: results of one-year exposure

ABSTRACT

An atmospheric corrosion campaign was carried out to update the information on the environmental corrosivity in Portugal, available from earlier MICAT and ICP-Materials projects. This communication summarises the initial atmospheric corrosion of copper, zinc and grey cast iron in the cities of Coimbra and Aveiro. The new data was produced in the scope of the project TRAPHIC, which aimed at evaluating the effects of air pollution on materials in the city of Coimbra. Samples of the three metals were exposed in three different locations and the surface modifications were monitored over time together with the local environmental conditions. Chromatic alterations in copper and zinc were analysed and corrosion products were characterised using SEM/EDS. First-year corrosion rates were measured for the three locations to complement the national corrosivity map. Results indicate the reduction of acidic pollution and decreasing of corrosion rates over the past 30 years in Portugal.     

Formation, Retention, and Loss of the Metals Atmospheric Corrosion Products. 1. The Integral Weight Model of the Products Formed

Changes of the total weight of tested samples, as well as changes in the weight of the retained atmospheric corrosion products, are studied as functions of corrosion losses in different climate zones and different test duration, for carbon steel, zinc, copper, magnesium, aluminum, Д16 and AMЦ alloys, and brass. An experimental mathematical model for integral weight of formed corrosion products is suggested. Climate effects on the change in the weight of corrosion products retained by metals are studied during long-term exposure of plates and wire spirals recommended by the ISO 9226-92 Standard for the monitoring of atmospheric corrosivity.__________Translated from Zashchita Metallov, Vol. 41, No. 4, 2005, pp. 402–416.Original Russian Text Copyright © 2005 by Panchenko, Strekalov.     

Estimating the gas permeability of commercial volatile corrosion inhibitors at elevated temperatures with thermo-gravimetry

Volatile corrosion inhibitors (VCIs) are incorporated into packaging paper or film to protect metals against atmospheric corrosion. The vapour pressure determines the equilibrium concentration of a volatile corrosion inhibitor (VCI) in the surrounding atmosphere. However, the rate at which the VCI can be delivered across the air gap to a metal surface is determined by the gas permeability. This is the product of the vapour pressure and the diffusion coefficient: S_A = P_AD_AB. The gas permeability of commercial VCIs was estimated at elevated temperatures from vaporisation rates measured using a simple thermo-gravimetric method (TG).     

The influence of an isobutane-SO2 pollutant system on the earlier stages of the atmospheric corrosion of metals

Whilst much research upon atmospheric corrosion has involved SO₂, the pollutant smoke aerosol and associated sorbed hydrocarbons have been largely ignored. As a preliminary study, the present work concerns the corrosivity of air-based atmospheres containing 50 vpm isobutane and/or 3.5 ppm SO₂ at 78 % r.h. It was found that, relative to a clean air atmosphere, isobutane inhibited the corrosion of iron and nickel whilst having rather less effect upon zinc, aluminium and copper. isobutane inhibited the corrosivity of SO₂ to iron, whilst conversely enhancing the corrosivity of SO₂ to aluminium, copper, nickel and zinc. In order to account for these results, proposed explanations involve the molecular dipole polarization of isobutane, its adsorption and coordination association at anodic and cathodic sites, affecting electrochemical reactions both directly and indirectly by mass transfer limitations, and its interference with maintenance repair reactions on surface layers.     

Comparative estimation of long-term predictions of corrosion losses for carbon steel and zinc using various models for the Russian territory

Based on the results of 1-year tests at 12 sites in the Far Eastern region of Russia, priority dose–response functions (DRFs) that provide the best match with experimental data on corrosion losses for carbon steel and zinc have been selected. Long-term (up to 50 years) predictions of corrosion losses of these metals in the continental territory of Russia have been given. A comparative estimation of the mass loss predictions by priority DRFs and the power–linear model has also been given.     

基于电偶的大气腐蚀性检测仪的研制及应用

针对大气腐蚀研制了基于电偶的大气腐蚀性检测仪,其对电偶电流进行模拟积分，输出电偶电量值，用来研究金属材料的大气腐蚀性.并用于不同氯离子浓度薄液膜下LY12铝合金大气腐蚀性检测，结果表明该仪器具有较好的性能，可用于现场测试和监测.     

Atmospheric corrosion of ASTM A-242 and ASTM A-588 weathering steels in different types of atmosphere

The work analyses the atmospheric corrosion resistance of two widely used weathering steels: ASTM A-242 and ASTM A-588. The steels were exposed for up to 5 years in different types of atmosphere: rural, urban, industrial and marine. The atmospheric corrosion resistance of the steels was evaluated and the rust layers formed on them were characterised by X-ray diffraction, optical microscopy and scanning electron microscopy. The most relevant conclusions reached include the following: (a) the visual appearance (colouring) of the rust, rust texture, nature of the corrosion products and compactness of the rust layers formed are similar in both types of weathering steel. (b) No great differences are observed in the corrosion resistance. Slight differences occur in the industrial atmosphere, where ASTM A-242 presents 10–13% less corrosion than ASTM A-588. (c) In the C2-C3 ISO corrosivity atmosphere both types of weathering steels are adequate for unpainted use. However are not suitable in higher ISO corrosivity atmosphere.     

Electrochemical monitoring of atmospheric corrosion phenomena

An atmospheric corrosion monitor (ACM) which consists of $\text{Cu}\text{Zn}$ or Cu/steel couples, has been used to study various aspects of atmospheric corrosion. Calibration of ACM's is carried out under 1 ml of distilled water. Measurements under 10^?510^?1N KCl show that the conductivity of the electrolyte is not an important parameter in determining the amount of current flow. A detailed study was related to the effect of salt particles on atmospheric corrosion. While no current flow and no corrosion occurred on clean surfaces up to r.h. ≈ 95%, large increases of the galvanic current were observed when salt particles were placed on the ACM surface provided that the relative humidity in the test cell was higher than the r.h. value of a saturated solution of the salt particle applied. The ACM has also been used to monitor changes in the composition of gaseous atmospheres (air, N₂, N₂ plus SO₂). Outdoor exposure of the $\text{Cu}\text{Zn}$ and Cu/steel ACM suggests that this instrument can be used not only to monitor time-of-wetness, but also the corrosivity of a test environment.     

Measurements of pitting corrosion currents of zinc in near neutral media

Using a simple model cell the susceptibility of the zinc electrode to pitting corrosion by SO₄²⁻, SO₃²⁻, S₂O₃²⁻ and S²⁻ anions were examined in naturally aerated carbonate solutions. It was found that, pitting started after an induction period, τ, which depended on the type and concentration of the aggressive and passivating anions. The pitting corrosion current increased with time until steady state values were attained. These values depended on both the type and the concentration of the passivating and pitting anions. For the same concentration of the passivating anions, the corrosion current varied with the concentration of the aggressive anion according to the relation: logi_pit.=a₁+b₁logC_agg. At a constant concentration of the aggressive anion, the corrosion current varied with the concentration of the passivating anions according to: logi_pit.=a₂−b₂logC_pass. The constants a₁ (a₂) and b₁ (b₂) were determined for all the systems studied. From the values of a₁ the corrosivity of the sulphur-containing anions is found to decrease in the order SO₄²⁻>SO₃²⁻>S₂O₃²⁻>S²⁻.     

Short-term atmospheric corrosion of mild steel at two weather and pollution monitored sites

Results are recorded of topographical details, weight loss and corrosion product analysis for short-term atmospheric exposure of mild steel, in relation to weather and pollutant factors. Various structured corrosion features, e.g. doughnut-like, were noted. The major corrosion product found was γ-Fe₂O₃,H₂O, with some α-Fe₂O₃,H₂O and α-FeOOH.Wet initial conditions of exposure and subsequent high levels of humidity, were found to have the dominant overriding effect in promoting corrosion losses. Smoke was shown to be capable of exerting a very strong influence upon the effective corrosivity of atmospheric sulphur dioxide.     

Corrosion Protection of Steel Highway Bridges: II Characterisation of bridge locations by corrosion and environmental measurements

Abstract

Climatological and air pollution factors greatly affect the corrosion damage to steel highway bridges. This paper gives first results of a programme to define quantitative criteria by which the potential corrosivity of a prospective bridge location can be assessed.

At seven sites throughout the country, the corrosion rates of a special mild steel, a low alloy steel and zinc are being measured under both open and sheltered exposure conditions. Meteorological and air pollution data are also being collected.

To eliminate the considerable delays which can occur in negotiating the building of permanent test compounds, a mobile test rig has been developed, which can be easily transported to any prospective bridge location.From the first year's results, it is apparent that sheltered test specimens give a much closer indication of the corrosivity under a bridge deck than do open exposure specimens. Of the environmental factors, atmospheric chlorides and sulphur compounds are the major factors influencing corrosion rate. It was not possible, at this stage of the work, to produce a correlation between corrosion rates and meteorological data.