Static atmospheric testing, metallic

The most widely used simulated service test for static atmospheric testing is described in ASTM G 50, Practice for Conducting Atmospheric Corrosion Tests on Metals. It is used to test coated sheet steels for a variety of outdoor applications. Test materials, which are in the form of flat test panels mounted in a test rack (Fig. 16), are subjected to the cyclic effects of the weather, geographical influences, and bacteriological factors that cannot be realistically duplicated in the laboratory. Test durations can last from several months up to many years. Some zinc-coated steel specimens have undergone testing for more than 30 years. 

The oscillations of atmosphere fluctuation occur with a frequency in the order of 1 Hz, and the catalytic activities are greatly affected by the species of noble metals and exhaust gas conditions. Figure 4 shows the NOx conversion efficiency on a Pd catalyst as a function of oscillating periods and amplitudes in an engine test (Yokota et al., 1985). This figure indicates that there are suitable cycling conditions, which the catalytic activities are superior to that under the static condition, and the catalyst performance depends on the cycling... 

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