A. A. Mikhailov

The classification system of ISO 9223 Standard and the dose-response functions assessing the corrosivity of outdoor atmospheres

The ISO 9223 Standard “Corrosion of Metals and Alloys–Corrosivity of Atmosphere–Classification” which is now in force was based on the data obtained mainly in the temperate climate of Europe and North America. At present, it is being revised by using data from new programs of atmospheric tests carried out in cold, temperate, subtropical, and tropical climates. The paper tackles problems of assessing the atmospheric corrosivity from the environmental parameters. A model and dose–response functions characterising the corrosivity of the outdoor atmospheres are described. Suggestible ways of possibly improving the standard with the use of the functions derived are considered.

Model for the Prediction of the Time of Wetness from Average Annual Data on Relative Air Humidity and Air Temperature

The data of the program designed by the Economic Commission for Europe of the United Nations Organization (UN ECE) to estimate the effect of air pollution on materials, including historical and cultural heritage, were used to study the relation between the time of wetness (TOW), temperature (T), and relative air humidity (Rh). The new relation resulting from the analysis allows one to predict TOW from average annual T and Rh. The relation is a conceptual and prognostic improvement of the previous ones describing TOW as functions of T and Rh. The parameters of the equation were determined from the data of the UN ECE program and verified with the use of ISOCORRAG/MICAT and Russian data in the temperature range from –16 to 28°C. The new relation allows TOW to be easily calculated, including classification purposes.

Dose-Response Functions as Estimates of the Effect of Acid Precipitates on Materials

This paper presents a brief summary of the findings of the 8-year exposure program of the European Economic Commission, United Nations (UN EEC), on estimating the effect of acid precipitates on materials, including historical and cultural monuments. Presented and discussed are dose-response functions for structural metals and alloys (bronze, copper, weathering steel, zinc, aluminum, nickel and tin), stone materials (limestone and sandstone), paint coatings and glasses. The effects of dry and wet precipitates are discriminated and expressed as separate doze-response functions. The corrosion damage to the majority of materials is most of all aggravated by dry precipitates of sulfur dioxide, while copper and tin suffer concurrently from ozone. In the equations the term pertaining to the dry precipitates includes a complex temperature effect. Unlike the correlations obtained upon four years of tests, the new functions include an “exposure time” parameter which enables one to calculate the corrosion rate at any period of time and to estimate the service life of the object at a given critical rate of corrosion.

Atmospheric corrosion of metals in regions of cold and extremely cold climate (a review)

The results of atmospheric corrosion tests on a series of metals and alloys in marine and industrial atmospheres of the Earth’s regions with cold and very cold climate (Antarctic, sub-Arctic, Russian Far East) are considered. The class of most dangerous corrosive damage includes special types such as pitting, exfoliation corrosion, crevice corrosion and corrosion-induced cracking. Long-term prognosis is made concerning the influence of global warming on the atmospheric corrosion in cold climate regions.

Atmospheric corrosion in tropical and subtropical climate zones: 3. Modeling corrosion and dose-response function for structural metals

The results of statistical analysis of a corrosion-climate database are presented. New dose-response functions have been obtained by methods of multiple and nonlinear analysis for evaluating corrosion-related weight losses of structural metals in the regions with humid tropical and subtropical climate.

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.