Mechanisms and differences between dew point corrosion, pitting corrosion, and crevice corrosion, [Video] Chemical Industry Weekly, Episode 76 fs01

Dew point corrosion, pitting corrosion, and crevice corrosion are all types of local corrosion; the difference lies in the location where the corrosion occurs and its causes: * **Dew point corrosion:** It occurs in areas on the metal surface where there is a layer of condensed water, and the oxygen and impurities dissolved in this water layer cause corrosion. It is mainly determined by environmental humidity and temperature. * **Pitting (punctate corrosion): Occurs in small focal areas on the metal surface; it is usually caused by the breakdown of the passivation film, resulting in the formation of highly active regions that lead to intense corrosion. It is closely related to the composition of the material and specific ions in the environment, such as chloride ions. * **Crevice corrosion:** It occurs in the gaps where metal surfaces are in close contact; the reduced oxygen concentration in these gaps creates a differential aeration cell, leading to accelerated corrosion of the metal within those gaps. Both the geometry of the gap and the composition of the surrounding medium affect its occurrence. In summary, although all three types of corrosion are forms of local corrosion, their locations of occurrence, causes, and corrosion processes differ. .