Field Study of Weather Conditions Affecting Atmospheric Corrosion by an Automobile-Carried Atmospheric Corrosion Monitor Sensor

The atmospheric corrosion of iron and steels not only affects the safety of infrastructures but also destroys the appearances and ornamental appreciations. The corrosivity of an environment can suggest such information that is useful for corrosion protection design and maintenance. The classical exposure test method is applicable to the evaluation of atmospheric corrosivity, but it takes a long time and can't tell the evolution of corrosivity over a period of time. Atmospheric corrosion monitor (ACM) has been proved to be an effective method to investigate the corrosivity of atmospheric environment. However, unfortunately, the experiences of the authors of this paper show that the output by measuring current is interfered by the noise when the sensor is dry, and it is often difficult to differentiate it from the background signals, while the corrosion process is still going on the sensor surface. In this paper, a Fe-Zn ACM sensor was modified by connecting a larger resistor in parallel and measuring the electromotive force. Laboratory experiments and field tests revealed the influence of temperature, RH and rainfall on the ACM outputs, verifying the applicability of the modified sensor for the monitoring of the corrosivity variations in a region.