Four jobs,
Zinc protects steel, forms precise metal parts, keeps the human body running and stores electrical energy. Here is how.
Galvanizing: armor for steel
Roughly half of all zinc produced goes into galvanizing — coating steel with a thin layer of zinc so it doesn’t rust. Steel is usually dipped in a bath of molten zinc (hot-dip galvanizing) or coated continuously as sheet on a production line.
The coating works in two ways. First, it is a barrier that keeps water and oxygen away from the steel. Second, it offers sacrificial protection: zinc is more electrochemically active than iron, so if the coating is scratched, the zinc around the scratch corrodes first and keeps protecting the exposed steel underneath.
That is why galvanized steel shows up in bridges, guardrails, power-line towers, solar mounting structures, farm equipment, fasteners and car bodies. A well-galvanized structure can go for decades with little maintenance.
Die casting: precision in metal
In die casting, molten metal is forced under pressure into a hardened steel mold (a die), then ejected as a finished or nearly finished part. Zinc alloys — most famously the Zamak family (zinc with small amounts of aluminum, magnesium and copper) — are among the easiest metals to die cast.
Zinc melts at a relatively low temperature and flows very well, so it can fill fine details and thin walls with tight tolerances and a smooth surface ready for plating or painting. Dies also tend to last a long time with zinc. The results are strong, precise parts: automotive components such as door-lock housings, seat-belt and sensor parts, plus hardware, electronics housings, connectors and fittings.
For the very lightest parts in cars and aircraft, engineers usually turn to aluminum and magnesium die castings, which are much less dense. Zinc’s strengths are precision, strength, fine finish and the ability to make small, intricate parts in high volume — often letting designers use thinner walls and less material overall.
Zinc in the human body
Zinc is an essential trace mineral: the body needs it in small amounts every day and has no special way to store it. It is part of hundreds of enzymes and helps the body make proteins and DNA.
Zinc supports normal immune function and plays a role in wound healing, growth and development, and the senses of taste and smell. Common food sources include meat, shellfish (oysters are especially rich), beans, nuts, whole grains and dairy.
This is general information only, not medical advice. Too much zinc can also be harmful. Talk to a doctor or other qualified health professional before taking supplements.
Zinc in batteries
Zinc has been storing energy since the earliest batteries. It is a good anode material: it gives up electrons readily, works in water-based electrolytes, and is cheap and abundant.
Alkaline cells
The everyday AA and AAA batteries in remotes and flashlights are zinc–manganese dioxide cells, with zinc as the anode.
Zinc-air
The tiny button cells in most hearing aids are zinc-air batteries. They draw oxygen from the air as a reactant, which gives them high energy for their size.
Grid storage (emerging)
Newer rechargeable zinc chemistries — zinc-ion, zinc-bromine, nickel-zinc and rechargeable zinc-air — are being developed and deployed to store solar and wind power. More on where it’s headed →