Zinc (Zn)
Zinc is primarily used as a protective coating for steel (galvanizing accounts for ~60% of zinc consumption) and as a base metal for die casting alloys. Its low melting point, excellent castability, and sacrificial corrosion protection properties make it essential in construction, automotive, and hardware industries.
Properties
- Density
- 7,134 kg/m³
- Melting Point
- 419.5 °C
- Boiling Point
- 907 °C
- Thermal Conductivity
- 116 W/(m·K)
- Electrical Resistivity
- 5.9 × 10⁻⁸ Ω·m
- Tensile Strength
- 120–350 MPa (alloys)
- Yield Strength
- 80–290 MPa (alloys)
- Hardness
- 30–120 HB
- Elongation
- 1–10%
- Crystal Structure
- HCP
Common Grades
- Zn 99.995% (SHG): Special high-grade zinc. Primary feedstock for galvanizing and alloy production.
- Zamak 3 (ZnAl4): Most widely used zinc die casting alloy. Good balance of strength, ductility, and castability.
- Zamak 5 (ZnAl4Cu1): Higher-strength die casting alloy with copper addition. Automotive and hardware components.
- ZA-27: Highest-strength zinc-aluminum alloy (27% Al). Bearing applications, heavy-duty components.
Applications
- Galvanizing: Hot-dip galvanizing of structural steel, continuous galvanizing of sheet, electro-galvanizing
- Die Casting: Automotive trim, hardware, zippers, locks, electronic housings, toys
- Construction: Roofing, gutters, flashings, rainwater goods (zinc-titanium alloys)
- Batteries: Alkaline batteries, zinc-air batteries, zinc-carbon cells
FAQ
How does zinc galvanizing protect steel?
Zinc provides dual protection: a barrier coating preventing moisture reaching the steel, and cathodic (sacrificial) protection where zinc corrodes preferentially even at scratches or cut edges. Hot-dip galvanizing per ISO 1461 typically provides 50–100+ years of protection depending on environment.
What is the difference between hot-dip and electro-galvanizing?
Hot-dip galvanizing (ISO 1461) immerses steel in molten zinc at 450°C, producing thick coatings (45–200 μm) with metallurgical bonding. Electro-galvanizing deposits thinner coatings (5–25 μm) via electroplating, offering better surface finish but less corrosion protection.
What are Zamak die casting alloys?
Zamak (Zamak = Zink, Aluminium, MAgnesium, Kupfer) alloys are zinc-aluminum casting alloys. Zamak 3 (4% Al) is the most common, offering an ideal balance of strength, ductility, and castability. Zinc die casting produces the tightest tolerances and thinnest walls of any metal die casting process, at the lowest cost per part.