🔍 Key Concepts

• Galvanic (cathodic) protection between dissimilar metals • The role of coatings like zinc and cadmium on steel in a corrosive (saltwater) environment • How a more active (anodic) metal protects a less active metal

💭 Think About

• Think about what happens in a saltwater environment when two different metals are in electrical contact. Which one corrodes first, and how does that affect the other metal? • Why are zinc anodes commonly bolted to hulls, rudders, and shafts on ships? What kind of protection does that provide to the steel? • Which answer choice best describes a coating that is intentionally allowed to corrode so the underlying metal does not?

✅ Before You Answer

• Verify which type of protection involves a more reactive metal corroding first to protect the base metal. • Eliminate options that describe heat resistance or surface sealing rather than controlled corrosion. • Confirm that cadmium and zinc are used in marine practice as anodes for corrosion protection, not primarily as a barrier sealant.