Two of the most important testing parameters, the wet/dry ratio and the temperature, were varied in order to study their influence on the extent of perforation corrosion of automobile materials. The results are compared with results from field exposures performed at the marine site of Bohus Malmön (Sweden) and with results from mobile exposure. In situ measurements of the galvanic current and the electrochemical impedance of the confined surface were used to determine the degree of macrowetness and the corrosion rate respectively. Three different cyclic corrosion tests (denoted CCT A, CCT B and CCT C) were used. From the results it is shown that both the drying time and the temperature are important factors when designing cyclic corrosion tests for perforation corrosion of automotive materials. The crevice never completely dried when using short drying times, resulting in a 'salt spray effect' in the confined area. An increase in the temperature from 35 to 50 deg C resulted in a drastic increase in the corrosion rate of zinc. Accelerated corrosion tests developed for the evaluation of cosmetic corrosion of automotive materials cannot directly be used for the evaluation of perforation corrosion of automotive materials. To obtain better correlation with outdoor exposures, emphasis should be placed on parameters such as drying time and temperature inside the crevice.
Perforation corrosion of automotive materials: comparison between laboratory and field exposures
Durchbruchskorrosion von Automobilwerkstoffen: Vergleich zwischen Labor- und Feldauslagerung
British Corrosion Journal ; 35 , 3 ; 195-203
2000
9 Seiten, 11 Bilder, 7 Tabellen, 14 Quellen
Aufsatz (Zeitschrift)
Englisch
Automobilindustrie , verzinkter Stahl , Laboratoriumsversuch , Feldversuch , Feuchte , Trocknen , Temperaturabhängigkeit , Salzsprühprüfung , Korrosionsgeschwindigkeit , Messgenauigkeit , Strommessung (elektrisch) , Gewichtsverminderung , zyklische Belastung , Meeresatmosphäre , Impedanzspektrometrie , galvanischer Strom , In-Situ-Messung
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