Johan Tidblad

Effects of air pollution on materials and cultural heritage: ICP materials celebrates 25 years of research

An overview is given of all results from the International Co-operative Programme on Effects on Materials including Historic and Cultural Monuments (ICP Materials), which was launched in 1985. Since then, about twenty different materials have been exposed repeatedly in a network of test sites consisting of more than twenty sites with an extensive environmental characterisation and more than sixty official reports have been issued. Recent results on trends in corrosion, soiling, and pollution show that corrosion of carbon steel, zinc, and limestone is today substantially lower than 25 years ago, but while corrosion of carbon steel has decreased until today, corrosion of zinc and limestone has remained more or less constant since the turn of the century. Unique data are given on measured HNO3 concentrations from 2002-2003, 2005-2006, and 2008-2009, and the relative average decrease was about the same from 2002-2003 to 2005-2006 as it was from 2005-2006 to 2008-2009.

UN ECE ICP Materials: Dose-Response Functions on Dry and Wet Acid Deposition Effects After 8 Years of Exposure

The main results of the International Co-operative Programme on Effects on Materials, including Historic and Cultural Monuments (ICP Materials) within the United Nations Economic Commission for Europe (UN ECE) are summarised. The 8-year field exposure programme involves 39 test sites in 12 European countries and in the United States and Canada. Dose-response functions (DRF) expressing the effect of dry and wet deposition as individual terms have been obtained for a wide range of materials including bronze, copper, weathering steel, zinc, aluminium, nickel, tin, stone materials, paint coatings and glass materials. The DRFs includes parameters that are easily available on different geographical scales and can be used for mapping areas of increased corrosion rates and for calculation of costs.

Plasma modification of mica

Abstract When mica is exposed to a low temperature nonpolymer-forming plasma the surface structure is altered by a combination of sputtering and chemical reaction with reactive species in the plasma. The chemical composition of the surface is altered without a significant increase in surface rougness under optimal conditions. The effect of the plasma process parameters (exposure time, power, flow rate, and pressure) on the extent of surface modification has been investigated by means of ESCA and contact angel measurements. After exposure to water vapor plasma the mica surface becomes reactive to silanation with chlorosilanes in the gas phase. The durability of mica surfaces modified by plasma treatment and subsequent reaction with some chlorosilanes has been investigated. The forces between water and plasma-treated surfaces after silanation have been measured using a surface force apparatus.

Atmospheric Corrosion : Second Edition

Presents a comprehensive look at atmospheric corrosion, combining expertise in corrosion science and atmospheric chemistry Is an invaluable resource for corrosion scientists, corrosion engineers, a ...

Modelling and mapping of copper runoff for Europe

A predictive runoff rate model for copper has been refined and used to generate copper runoff maps for Europe. The new model is based on laboratory and field runoff data and expresses the runoff rate R (g m(-2) yr(-1)) through two contributions, both with a physical meaning: R = (0.37SO(0.5)(2) = 0.96 rain10(-0.62 pH) (cos(theta)/cos(45 degree)). Input parameters are the SO(2) concentration (microg m(-3)), pH, amount of rain (mm yr(-1)), and surface angle of inclination (theta). The first contribution originates from dry periods between rain events (the first-flush effect) and the second from the rain events. The dry term has been refined in comparison to the original model by assuming a mass balance between measured corrosion mass loss, calculated copper retention in the patina and predicted copper runoff. The refined model predicts 76% of all reported runoff rates, worldwide, within 35% from their measured value. This includes sites with low SO(2) concentration, where the original model erroneously predicted higher runoff rates than corrosion rates. Based on environmental data from the EMEP programme for the years 1980-2000, the new model has been used to derive runoff rate maps for Europe with 50 x 50 km grid resolution. The runoff mapping shows a substantial reduction in runoff rate over the investigated time period, and with copper runoff rates now generally less than 2 g m(-2) yr(-1).

GILDES Model Studies of Aqueous Chemistry VI. Initial S O 2 ∕ O 3 - and S O 2 ∕ N O 2 -Induced Atmospheric Corrosion of Copper

GILDES, a computer-based model of atmospheric corrosion, has been used to simulate copper exposed at room temperature to 200 ppb SO 2 in combination with either NO 2 or O 3 at different concentrations. The GILDES model involves the five most important regimes in atmospheric corrosion (gas, liquid, deposition, electrodic, and surface) and includes 27 aqueous species and more than 60 aqueous reactions. Under these exposure conditions copper forms cuprite (Cu 2 O) and various copper sulfates in both SO 2 + NO 2 and SO 2 + O 3 mixtures, and copper hydroxynitrate in SO 2 + NO 2 after an incubation time of 4 h. Among these experimental observations the GILDES model correctly predicts the formation of copper sulfate (in both SO 2 + O 3 and SO 2 + NO 2 mixtures) and copper hydroxynitrate (SO 2 + NO 2 ). It is furthermore able to predict the formation rate of copper sulfate in SO 2 + O 3 mixtures, but not the formation rate of copper sulfate and copper hydroxynitrate in SO 2 + NO 2 mixtures.

Atmospheric Corrosion Effects of HNO3 A Comparison of Laboratory and Field Exposed Copper, Zinc, and Carbon Steel

The role of nitric acid (HNO3) on the atmospheric corrosion of metals has so far received little or no attention. However, the last decades of decreasing sulphur dioxide (SO2) levels and unchanged HNO3 levels in many industrialized countries have resulted in an increased interest in possible HNO3-induced atmospheric corrosion effects. In this study a new method was developed for studying the corrosion effects of HNO3 on metals at well-defined laboratory exposure conditions. The method has enabled studies to be performed on the influence of individual exposure parameters, namely HNO3-concentration, air velocity, temperature and relative humidity, as well as comparisons with newly generated field exposure data.The corrosion rate and deposition rate of HNO3 on copper was shown to follow a linear increase with HNO3 concentration. The deposition velocity (Vd) of HNO3 increased up to an air velocity of 11.8 cm s-1. Only at a higher air velocity (35.4 cm s-1) the Vd on copper was lower than the Vd on an ideal absorbent, implying the Vd of HNO3 at lower air velocities to be mass-transport limited.Within the investigated temperature range of 15 to 35 oC only a minor decrease in the HNO3-induced copper corrosion rate could be observed. The effect of relative humidity (RH) was more evident. Already at 20 % RH a significant corrosion rate could be measured and at 65 % RH the Vd of HNO3 on copper, zinc and carbon steel reached maximum and nearly ideal absorption conditions.During identical exposure conditions in HNO3-containing atmosphere, the corrosion rate of carbon steel was nearly three times higher than that of copper and zinc. The HNO3-induced corrosion effect of copper, zinc and steel turned out to be significantly higher than that induced by SO2 alone or in combination with either NO2 or O3. This is mainly attributed to the much higher water solubility and reactivity of HNO3 compared to SO2, NO2 and O3. Relative to SO2, zinc exhibits the highest sensitivity to HNO3, followed by copper, and carbon steel with the lowest sensitivity.Extrapolation of laboratory data to an assumed average outdoor wind velocity of 3.6 m s-1 enabled a good comparison with field data. Despite the fact that ambient SO2 levels are still much higher than HNO3 levels, the results show that HNO3 plays a significant role for the atmospheric corrosion of copper and zinc, but not for carbon steel. The results generated within this doctoral study emphasize the importance of further research on the influence of HNO3 on degradation of other materials, e.g. stone and glass, as well as of other metals.

ICP Materials trends in corrosion, soiling and air pollution (1987–2014)

Results from the international cooperative programme on effects on materials including historic and cultural monuments are presented from the period 1987–2014 and include pollution data (SO2, NO2, O3, HNO3 and PM10), corrosion data (carbon steel, weathering steel, zinc, copper, aluminium and limestone) and data on the soiling of modern glass for nineteen industrial, urban and rural test sites in Europe. Both one-year and four-year corrosion data are presented. Corrosion and pollution have decreased significantly and a shift in the magnitude is generally observed around 1997: from a sharp decrease to a more modest decrease or to a constant level without any decrease. SO2 levels, carbon steel and copper corrosion have decreased even after 1997, which is more pronounced in urban areas, while corrosion of the other materials shows no decrease after 1997, when looking at one-year values. When looking at four-year values, however, there is a significant decrease after 1997 for zinc, which is not evident when looking at the one-year values. This paper also presents results on corrosion kinetics by comparison of one- and four-year values. For carbon steel and copper, kinetics is relatively independent of sites while other materials, especially zinc, show substantial variation in kinetics for the first four years, which needs to be considered when producing new and possibly improved models for corrosion.

Acid Deposition Effects on Materials: Evaluation of Electric Contact Materials after 4 Years of Exposure

In 1987 a co-operative field exposure program within the UN Economic Commission for Europe was initiated. The aim of the program is to evaluate the effect of sulfur pollutants in combination with NO x and other pollutantson the atmospheric corrosion of important materials. This work presents results from the evaluation of the electric contact materials nickel, copper, silver and tin after 4 years of exposure. Dry deposition of SO 2 dominates the corrosion of nickel, which forms amorphous and crystalline basic nickel sulfate, whereas both O 3 and NO 2 accelerate the dry deposition of SO 2 on copper. Silver forms Ag 2 S as the dominating corrosion product. Since H 2 S is not measured within the program it has not been possible to estimate its contribution. The formation of oxides with different stoichiometries dominates the corrosion of tin and no equation has been found that relates the weight increase of tin to environmental data. Particulate ammonium sulfate contributes to the weight increase of all metals.

Mapping of Acid Deposition Effects and Calculation of Corrosion Costs on Zinc in China

Corrosion damage to materials including objects of cultural heritage due to acid deposition has been shown to cause large costs in several studies in Europe and in the United States. So far no similar extensive studies have been performed in developing countries. The World Bank has therefore initiated and financed a study of the corrosion costs in China based on available data in the literature and obtained through contacts and visits to several institutes and organisations in China. An initial assessment of the corrosion costs in China due to acidifying pollutants has been performed using a model originally developed and applied in Europe, which has been adapted to conditions in China. Here, the model is described using zinc as an example. In the calculation of corrosion costs it is assumed that the stock of materials at risk can be allocated to census data, which enables a separate calculation of the cost for each province in China. The significant differences in corrosion attack is illustrated for zinc with a corrosion map of China based on environmental data and a dose-response function adapted for Chinese conditions including the dry and wet acid deposition effects as separate terms.