Meaning
Electrochemical measurement techniques that determine the current flowing between two electrodes without introducing an external voltage drop allow for the study of natural corrosion processes. In zero resistance ammetry, the instrument acts as a short circuit with negligible internal resistance to capture the galvanic current between dissimilar metals. This method provides a direct measurement of the corrosion rate in a coupled system.
Use of this technique is common in the evaluation of battery housing materials and terminal connections exposed to electrolytes.
Instrument Operation
Feedback circuits within the ammeter actively compensate for any voltage drop across the sensing element to maintain the electrodes at the same potential. Maintaining this balance ensures that the measured current reflects the spontaneous electrochemical activity of the materials. Traditional ammeters cannot perform this task because their internal resistance would throttle the very current they are trying to measure.
Corrosion Monitoring
Real time data shows how protective coatings or inhibitors perform under actual service conditions. If the galvanic current increases suddenly, it signals a breach in the coating or a change in the environment’s corrosivity. Success of zero resistance ammetry depends on selecting compatible metals for battery busbars and cooling plates.
Sensitivity Advantage
Capability to detect tiny currents makes this tool ideal for studying localized corrosion like pitting or crevice attack.
