Steel ship hulls in saltwater environments are highly vulnerable to galvanic corrosion caused by electrochemical reactions between dissimilar metals. To protect the primary steel structure, sacrificial anodes made of zinc or aluminum alloys are mounted directly to the hull below the waterline. Because zinc has a lower electrochemical potential than steel, the zinc anode oxidizes preferentially, corroding away while the steel hull remains protected as the cathode. Sacrificial anodes require zero external electrical power to function and are routinely inspected during drydock servicing. Technicians schedule replacement when an anode is depleted by approximately 50 percent of its original mass.
According to the passage, all of the following statements regarding sacrificial zinc anodes are true EXCEPT:
- AThey oxidize preferentially to prevent the ship's steel hull from corroding.
- They require a continuous supply of external electrical power to function.Cevap
- CThey are attached directly to sections of the hull situated below the waterline.
- DThey are scheduled for replacement once roughly 50 percent of their mass has eroded.