Principle of ACM Corrosion

The cumulative duration exceeding the threshold (e.g., 50 nA) is the dew/film duration, a core metric for ISO 9223 atmospheric corrosion classification. Charge quantity Q
(coulombs C)

The time integral of current represents the total corrosion charge over a given period. The core principle of ACM galvanic current is that two metals are insulated on the substrate
and short-circuited externally with a zero-resistance ammeter (ZRA), without applying any external excitation voltage, to monitor the corrosion activity of thin liquid films
(condensation) on steel structure surfaces. Common electrode pairings (anode-cathode) are used
Fe-Cu (carbon steel copper) is the most common
Fe-Ag (carbon steel silver, marine high-salinity environment)
Zn-Cu, Al-Cu (corresponding to zinc and aluminum substrate monitoring)
Principle of ACM Sensors For example, in high-salinity marine environments, when a water film forms on Fe/Ag and ACM sensors, Fe releases electrons and undergoes corrosion.
If the Ag-Fe junction shorts under these conditions, corrosion information (in the form of current) can be extracted. By using a short-current measurement device (such as an
ACM data recorder) to observe this current, the galvanic current I (in units of nA/μA) of the ACM can be used to obtain real-time corrosion information. The current range of
the Wenzhou leakage corrosion sensor spans from extremely small to very large, allowing measurements with an automatic range, zero-resistance ammeter. It can also measure and
calculate required parameters such as temperature and humidity data