🔍 Key Concepts

• Galvanic (bimetallic) corrosion between dissimilar metals in the presence of an electrolyte (seawater) • The relative position of steel and aluminum in the galvanic (noble) series • Ways to interrupt electrical paths between dissimilar metals at joints

💭 Think About

• Ask yourself: Do we want steel and aluminum to be in good electrical contact, or do we want to prevent electrical current from flowing between them in seawater? • Consider what happens to the less noble (more active) metal when it is directly connected to a more noble metal in a saltwater environment. • Think about common shipbuilding practice: when mounting aluminum fittings on a steel structure, what do shipyards typically insert at the joint to control corrosion?

✅ Before You Answer

• Verify which choice prevents or reduces electrical continuity between the two plates at the joint. • Check which answer mentions non-conductive (insulating) materials rather than increasing metal-to-metal contact. • Eliminate any options that suggest steel and aluminum are so close in the galvanic series that no special measures are needed.