The pure aluminium coating provides a dual purpose. What are they?

• A. It increases ductility and reduces weight.
• B. It prevents core contact with corrosive agents and protects the core from corrosion by scratching or abrasion.
• C. It acts as a primer for paints and improves adhesion.
• D. It improves thermal conductivity and magnetic properties.

Answer: (B)

The main idea is that a pure aluminum coating provides both a barrier protection and a wear-protective, sacrificial layer for the underlying material. As a barrier, the coating isolates the core from moisture, salts, and other corrosive agents, with aluminum’s adherent oxide film helping to resist corrosion and even heal minor scratches so the core remains protected. As a second function, if the coating is damaged by scratching or abrasion, the aluminum layer takes the hit, and because it is the more reactive surface, it can corrode in place of the core, preserving the integrity of the underlying metal. This dual role of blocking corrosive attack and absorbing wear damage is why the aluminum coating is valued. The other options don’t describe these corrosion-focused roles—ductility or weight, act as a paint primer, or alter thermal or magnetic properties.