Zinc

Most zinc is never seen as zinc: it is the coating that stops steel rusting, and it works by corroding preferentially rather than by sealing the surface, so a scratched galvanized panel still does not rust at the scratch. Its low melting point makes it the easiest common metal to die-cast, which is why cheap castings are usually zinc alloy. Highest thermal expansion of the common structural metals, at about two and a half times steel.

Properties

Density

7,140 kg/m³ — 7.14 g/cm³

Melting point

419.5 °C

Tensile strength

100–150 MPa

Young's modulus

108 GPa

Thermal conductivity

116 W/(m·K)

Thermal expansion

30.2 µm/(m·K)

Floats in water

No

Magnetic

No

What it is used for

• Galvanizing coatings on steel
• Die-cast carburettor bodies, locks and toy cars
• Sacrificial anodes on boats and water heaters
• Brass making

How it compares

Does it rust?

Zinc does not rust — rust is iron oxide specifically — but it does corrode, forming its own oxide or salts over time.

Is it magnetic?

Zinc is not ferromagnetic. It is often assumed to be because it is a metal, but most metals are not — only iron, nickel, cobalt and a few alloys are attracted to an ordinary magnet.