What is the mechanism of galvanic corrosion described as?

• A. A chemical dissolution without electrons
• B. A passive film breakdown only
• C. A purely mechanical wear
• D. A classical electrochemical cell

Answer: (D)

Galvanic corrosion happens when two dissimilar metals are in electrical contact in an electrolyte, forming a tiny battery. The more active metal becomes the anode and oxidizes, while electrons flow through the metal to the more noble metal, which acts as the cathode where reduction occurs. The electrolyte conducts ions to complete the circuit. This electrochemical process accelerates corrosion at the anode and can be influenced by factors like the metals’ potential difference and surface-area ratio. Describing it as a classical electrochemical cell captures the essential mechanism: electron transfer and redox reactions driven by the potential difference between the metals in the electrolyte. The other options skip this electrochemical aspect, focusing on dissolution without electrons, passive film breakdown, or purely mechanical wear, which are not the full mechanism of galvanic corrosion.