Atmospheric Test Sites Research Articles

Monitoring of the atmospheric corrosivity by resistive sensors

Abstract Atmospheric corrosivity is classified according to EN ISO 9223 Corrosion of metals and alloys – Corrosivity of atmospheres – Classification, determination and estimation. For the determination and estimation of the corrosivity category, standardized approaches are used. Monitoring of corrosivity with the application of various sensors is an actual trend. The paper gives results of verification of some types of sensors for this monitoring with standardized flat samples at atmospheric test sites in the Czech Republic. The trend of decreasing atmospheric corrosivity is evident in the last decade. Monitoring of the corrosion rate and mapping of the corrosivity become a very important step in preventing failures in long-term atmospheric exposition. This type of monitoring was used on bridge construction to estimate the seasonal effect of de-icing salts deposition, too.

Investigation of Surface Corrosion Morphology and Mass Change of Three Aluminum Aerospace Alloys As It Pertains to Corrosion Rate at Various Atmospheric Exposure Sites

Replicate coupons of bare aluminum alloys AA2024-T3, AA6061-T6, and AA7075-T6 are being exposed at two coastal atmospheric test sites, Kennedy Space Center (KSC) and the US Naval Research Laboratory in Key West, FL (NRL-KW). Various analyses including mass loss/mass gain determinations, elemental composition analysis (via scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS)), as well as pit density and pit volume measurements (via 3-dimensional laser/optical microscopy) are being performed to determine if there is a correlation between corrosion rate, corrosion morphology, and surface chemistries of the coupons exposed at the outdoor sites. The sample coupons are being retrieved at 3-month intervals. The aluminum alloy coupons are cleaned until a consistent change in mass between cleaning cycles has been reached per ASTM G1 (Table A1). At this point of the investigation, a cumulative exposure time of 6 months will be discussed and presented. Mass loss data for the bare metal substrates at the two field locations indicate that different mass losses occur at the two locations for similar exposure lengths for all three alloys, but at overlapping time intervals. For the AA7075-T6 alloy, mass gain (negative mass loss values) was measured for the 1Q (3 month) and 2Q (6 month) exposure at the NRL-KW site, whereas mass loss values (positive mass loss values) were determined for the KSC site for similar time exposures; however, replacement replicate AA7075-T6 coupon exposures at the NRL-KW site for the same length of exposure but at a different time interval, exhibited mass loss values (Figure 1).While the observed corrosion rates were different, it was determined that the morphology and elemental composition of the alloy substrates were different as well. Due to the extreme localized pitting attack on the 6061 and 7075 alloys, optical analyses of the coupons indicate that the resulting variability of the mass determinations may be due to incomplete removal of corrosion product from within the subsurface horizontal exfoliating pits populating the exposed coupons. Indeed, the populating of the coupons with these occluded pits was observed to increase with field exposure time at both field exposure sites, resulting in increased variability in mass loss values. These results reinforce the importance of deploying more than a single sample coupon of these aluminum alloys for corrosion rate calculations using mass loss determinations. Pit morphology and elemental analysis of the exposed alloy coupons as a function of exposure time and location will also be presented and discussed.These findings are important in developing accelerated test protocols. In previous laboratory exposure tests it was found that similar mass losses were observed at an accelerated rate in the modified chamber for these alloys versus the field exposures, but the surface morphology of the substrates exposed in the chamber were markedly different from the substrates in the field. Therefore, it may be more informative to consider the elemental composition, pit density and pit morphology of the corroded surface in addition to the mass loss, rather than rely on mass loss alone. Figure 1. Plot of mass loss comparison for aluminum alloys coupons exposed at KSC and NRL-KW for 3 and 6 months. Figure 1

WITHDRAWN: Correlation between the surface aging of acrylic polyurethane coatings and environmental factors

Abstract The effects of atmospheric environmental factors, such as temperature, humidity, solar radiation, and wind speed, on the early aging of acrylic polyurethane (PU) coating were studied via path analysis based on the apparent aging data of acrylic PU coatings and climatic environment data from 13 typical atmospheric test sites in China. The classification and refinement criteria for temperature, humidity, solar radiation, and wind speed were established using k-means clustering analysis. Then, the correlation model for the aging degree of acrylic PU coatings and climatic factors was established. The aging behavior of acrylic PU coatings in untested areas was predicted on the basis of atmospheric environment data from 97 cities in China. Finally, the light loss distribution of acrylic PU coatings in China was obtained.

Correlation between the surface aging of acrylic polyurethane coatings and environmental factors

The effects of atmospheric environmental factors, such as temperature, humidity, solar radiation, and wind speed, on the early aging of acrylic polyurethane (PU) coating were studied via path analysis based on the apparent aging data of acrylic PU coatings and climatic environment data from 13 typical atmospheric test sites in China. The classification and refinement criteria for temperature, humidity, solar radiation, and wind speed were established using k-means clustering analysis. Then, the correlation model for the aging degree of acrylic PU coatings and climatic factors was established. The aging behavior of acrylic PU coatings in untested areas was predicted on the basis of atmospheric environment data from 97 cities in China. Finally, the light loss distribution of acrylic PU coatings in China was obtained.

Prediction model of corrosion losses based on probabilistic approach

The article deals with the prediction of corrosion losses of weathering steels based on the application of dose-response functions. The following environmental characteristic incoming the dose-response functions are analyzed using statistic and probabilistic methods: mean annual values of the temperature T, concentration of sulfur dioxide SO2, relative air humidity RH, deposition of chlorides Cl-. Long-term measurements of environmental parameters at atmospheric test sites were used for the analysis. All the environmental parameters incoming the dose-response functions are considered to be random variables represented by corresponding histogram. Using the probabilistic analysis it is possible to predict the expected range of corrosion rates and to analyze the impact of particular environmental characteristic on corrosion process.

Atmospheric corrosion models

Abstract A number of damage functions or dose-response equation, which are compared to the atmospheric corrosion of metals with environmental parameters, have been determined in field programs ISOCORRAG, UN ECE ICP Materials Exposure Programme and Multi-Assess. The all of these dose-response equations are derived on field exposure results performed during period 1986-1995 where the SO2 level was relative high at urban and very high at industrial test sites. Several exposure programmes, national and international, of structural metals’ atmospheric corrosion were conducted since the 1970s on Czech atmospheric test sites including on-site measurement of environmental data. All data from these exposure programs were compared with prediction models.

Effect of Tropical Atmosphere on Corrosion of Different Metals: Corrosivity Measurements of Singapore

Corrosion influences and intrudes many parts of our lives. It can cause dangerous and expensive damages. Singapore obviously faces corrosion consequences though there is no direct evidence or record to justify how aggressive and diverse Singapore atmosphere is in terms of corrosion. However, now there is some light to shed these doubts as standardised atmospheric exposure tests have been established in Singapore. Atmospheric exposure test sites were setup at three locations of Singapore to represent marine, industrial and urban atmospheres or their mixtures. Salient atmospheric constituents or parameters like time of wetness, Cl-, SO2, NO2, O3, HNO3 have been measured in all sites over a period of time to categorise corrosivities of particular atmospheres. The effect of atmosphere on corrosion of Fe, Cu, Al and Zn also has been investigated and quantified. Subsequently, “estimated” and “determined” corrosivity values of Singapore according to ISO 9223:2012 were measured and recorded.

Miscarriages and Congenital Conditions in Offspring of Veterans of the British Nuclear Atmospheric Test Programme

A postal questionnaire case-control study examined miscarriage in wives and congenital conditions in offspring of the 2007 membership of the British Nuclear Test Veterans Association, a group of ex-servicemen who were stationed at atmospheric nuclear weapon test sites between 1952-67. Results were compared with a veteran-selected control group and also with national data. Based on 605 veteran children and 749 grandchildren compared with 311 control children and 408 control grandchildren there were significant excess levels of miscarriages, stillbirths, infant mortality and congenital illnesses in the veterans? children relative both to control children and expected numbers. 105 miscarriages in veteran?s wives compared with 18 in controls OR=2.75 (1.56, 4.91; p=.00016). There were 16 stillbirths; 3 in controls (OR=2.70 (0.73, 11.72; p=0.13). Perinatal mortality OR was 4.3 (1.22, 17.9; p=.01) on 25 deaths in veteran children. 57 veteran children had congenital conditions vs. 3 control children (OR=9.77 (2.92, 39.3); p=0.000003) these rates being also about 8 times those expected on the basis of UK EUROCAT data for 1980?-2000. For grandchildren, similar levels of congenital illness were reported with 46 veteran grandchildren compared with 3 controls OR=8.35 (2.48, 33.8) p=0.000025. There was significantly more cancer in the veteran grandchildren than controls. Whilst caution must be exercised due to structural problems inherent in this study we conclude that the veterans? offspring qualitatively exhibit a prevalence of congenital conditions significantly greater than that of controls and also that of the general population in England. The effect remains highly statistically significant even assuming a high selection bias in the responses and credibility is strengthened by the high rates of miscarriage reported by the veterans compared with controls, a result which could hardly have been due selection effects.

Performance evaluation of alkyd coatings for corrosion protection in urban and industrial environments

The performance of alkyd based coatings exposed in two different sites in Ecuador, urban and industrial locations, for corrosion protection was evaluated. Atmospheric test sites and corrosion resistance of coatings were examined using mainly ISO and ASTM standards. The alkyd resin degradation was characterized by different methods such as FTIR-ATR, DSC, TGA and SEM.The studies showed that the corrosion resistance and chemical structural changes were more evident for those samples exposed in the industrial environment although the sun radiation was lower than that measured in the urban location.

Looking Back on Contributions in the Field of Atmospheric Corrosion Offered by the MICAT Ibero-American Testing Network

The Ibero-American Map of Atmospheric Corrosiveness (MICAT) project was set up in 1988 sponsored by the International Ibero-American programme “Science and Technology for Development (CYTED)” and ended in 1994 after six years of activities. Fourteen countries were involved in this project: Argentina, Brazil, Chile, Colombia, Costa Rica, Cuba, Ecuador, Mexico, Panama, Peru, Portugal, Spain, Uruguay, and Venezuela. Research was conducted both at laboratories and in a network of 75 atmospheric exposure test sites throughout the Ibero-American region, thus considering a broad spectrum of climatological and pollution conditions. Although with its own peculiarities, the project basically followed the outline of the ISOCORRAG and ICP/UNECE projects, with the aim of a desirable link between the three projects. This paper summarizes the results obtained in the MICAT project for mild steel, zinc, copper, and aluminum specimens exposed for one year in different rural, urban, and marine atmospheres in the Ibero-American region. Complementary morphological and chemical studies were carried out using scanning electron microscopy (SEM) coupled with energy dispersive spectrometry (EDS), X-ray diffraction (XRD), and fourier transform infrared Spectroscopy (FTIR) techniques, in order to correlate climatic and atmospheric conditions and properties of the corrosion products.

Leaching studies on naturally weathered potash-lime–silica glasses

Within the international, EU-supported research project MULTI-ASSESS more than 150 glass samples with a chemical composition similar to medieval stained glasses were exposed in six European cities (Athens, Krakow, London, Prague, Rome and Riga) to the local environmental and climatic conditions. After exposure periods of 6 or 12 months the samples were investigated in the scanning electron microscope with energy dispersive X-ray microanalysis (SEM/EDX). Surface analyses indicate that the main weathering products were sulphates such as syngenite (CaSO4·K2SO4·H2O) and gypsum (CaSO4·2H2O). Chlorides, organic compounds and/or carbonates or nitrates of the elements K, Ca and Na were predominantly detected on the 6-months samples, whereas Si-containing compounds appeared particularly on the 12-months samples. Linescan measurements performed on the cross-sectioned glass samples allowed for the determination of leaching depths of the network modifier ions according to an evaluation procedure recently presented. The average leaching depths after 6 months of exposure were d(K)=0.88±0.43μm, d(Ca)=0.62±0.37μm, d(Na)=0.34±0.32μm and d(Mg)=0.16±0.18μm. After 12 months an average increase of the leaching depths between 38% (K) and 63% (Mg) is observed. No leaching could be determined for the network former elements Al and P. A clear influence of the environmental conditions at the atmospheric test sites on the degree of weathering was observed. In a first approximation, the leaching depths exhibit a linear dependence on a general pollution factor comprising the concentrations of the acidifying gases SO2, NO2 and O3.

Atmospheric corrosion of zinc Part 2: Marine atmospheres

AbstractThis paper summarises the results obtained in the MICAT (Mapa Ibero-Americano de Corrosao Atmosferica (Latin American Map of Atmospheric Corrosion)) atmospheric corrosion project (an Iberoamerican project on atmospheric corrosion, involving 14 countries and 75 atmospheric test sites) for zinc specimens exposed in the Latin American region for 1–4 years at 23 pure marine and 19 mixed marine (i.e. SO2 polluted) sites. The atmospheres at these sites were characterised climatologically and in terms of their pollution levels so that their corrosivity could be expressed in accordance with ISO standards. Morphological and chemical characterisation of the zinc corrosion product layers (ZCPLs) was performed using scanning electron microscopy coupled with energy dispersive spectrometry (SEM–EDS), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and soluble salt evaluation techniques. The results obtained show that the corrosion rate of zinc is a function of both the chloride pollutio...

Atmospheric corrosion of zinc Part 1: Rural and urban atmospheres

AbstractThis paper summarises the results obtianed in the MICAT (Mapa Ibero-Americano de Corrosao Atmosferica (Latin American Map of Atmospheric Corrosion)) atmospheric corrosion project (an Iberoamerican project on atmospheric corrosion, involving 14 countries and 75 atmospheric test sites) for zinc specimens exposed for 1–4 years in 21 rural and urban atmospheres of the Latin American region. During the study, all of these atmospheres were characterised according to international standards. Complementary morphological and chemical studies were carried out using scanning electron microscopy coupled with energy dispersive spectrometry (SEM–EDS), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR) techniques, in order to correlate atmospheric characteristics and the properties of zinc corrosion product layers (ZCPLs). Soluble salts retained in these ZCPLs were also determined. The study has provided clear evidence about the wide range of zinc corrosion rates occurring in rural atmos...

Corrosion performance of waterborne coatings for structural steel

Among recently developed waterborne coatings, epoxy and acrylic based coatings have a special place. To study this kind of anticorrosive coatings, use is normally made of natural exposure and laboratory tests. The literature has recently reported that the salt spray test is not suitable for selecting/studying anticorrosive waterborne coatings. In this paper, the authors present the main results obtained in an experimental study involving laboratory tests and natural exposure in two atmospheric test sites of different corrosivity categories. The natural exposure and accelerated tests are complemented by other measurements in the laboratory, involving water uptake, adhesion and electrochemical measurements, to understand the anticorrosive performance of the paint systems under study. As accelerated tests, salt spray and prohesion were used. Indirect measurements of adhesion were made using cross-cut and pull-off tests. Electrochemical impedance spectroscopy (EIS) and noise (EN) were used for electrochemical characterization. The study concludes that the best anticorrosive behaviour was shown by epoxy-polyamide paint systems, including zinc-rich primers. The correlation between the results of salt spray and natural exposure in marine test sites was significantly better than that obtained using the prohesion test. The electrochemical results showed that it is very important to pay special attention when interpreting this kind of results.

ChemInform Abstract: Mössbauer and X‐Ray Diffraction Phase Analysis of Rusts from Atmospheric Test Sites with Different Environments in Sweden.

AbstractAn 8 verschiedenen Orten in Schwe′den wurden unlegierte Stahlplatten der atmosphärischen Korrosion ausgesetzt (1 bzw. 5 Jahre) und die gebildeten Rostschichten durch "Fe‐Mößbauer‐ Spektroskopie sowie durch Röntgen‐Beugung (Pulver) untersucht.

Mössbauer and x-ray diffraction phase analysis of rusts from atmospheric test sites with different environments in Sweden

Rust samples from mild steel panels exposed at eight different atmospheric test sites in Sweden have been studied by transmission 57Fe-Mössbauer spectroscopy and X-ray powder diffraction. All samples exhibited superparamagnetic effects in Mössbauer spectra recorded at room temperature, due to fine particles. The corrosion products were mainly identified in low temperature (∼10 K) Mössbauer spectra and with X-ray powder diffraction. In all samples, α-FeOOH and γ-FeOOH were the main constituents (>70%). Only in the marine samples were β-FeOOH and Fe 3-σO 4 found. The α-FeOOH/γ-FeOOH ratio obtained was found to increase with the SO 2 concentration at the test sites.

Atmospheric Corrosion Sites in Europe available for Tests on Steel Protection: Report prepared for the European Federation of Corrosion Working Group No.2: Protection of Steel Structures against Corrosion

AbstractThe paper provides a list of 54 atmospheric corrosion test sites in various localities in Europe available for use for studying the protection of structural steel. The information supplied includes types of climate (rainfall, humidity, sunshine, temperature, etc.), details of atmospheric pollutants, convenient sizes for samples and how they are disposed on the exposure racks. Addresses of organisations in charge of the exposure sites are appended.

Corrosion of Metals in Tropical Environments (Part 2—Atmospheric Corrosion of Ten Structural Steels)

Abstract Results are reported of 8-year exposure tests made to determine the corrosion characteristics of ten structural steels exposed to seashore and inland environments in the Panama Canal Zone. These corrosion rates are compared with existing data for the same materials in temperate zones. Data reported include a summary of individual analyses of air samples obtained at atmospheric test sites, and extensive weight-loss and pitting data for the ten steels at 1, 2, 4 and 8-year exposure intervals. Numerous time-corrosion curves in tropical marine and tropical inland exposures are given for the steels. Considerable attention is given to the effect of low-alloy additions on mild carbon steel. It was found that the corrosion of copper steel in the two tropical atmospheres was only 13 percent and 14 percent less than that of the unalloyed mild steel. The 2 percent and 5 percent nickel steels were very effective in resisting corrosion as was nickel steel. The four proprietary low-alloy steels tested displaye...