Zirconium

Zirconium (chemical symbol Zr) is a chemical element with atomic number 40. It is a silvery-white, lustrous, hard metal that resists corrosion. It belongs to the transition metals in the periodic table, in the group containing titanium and hafnium.

Zirconium does not occur in nature as a pure element; it is found in minerals, particularly zircon (ZrSiO4) and baddeleyite (ZrO2). When refined, a thin oxide layer forms on the surface, protecting the metal from further corrosion. Zirconium powder is highly pyrophoric and ignites readily when exposed to air.

Physical and Chemical Properties

Zirconium has high melting and boiling points and resists most strong acids and bases. It typically exhibits an oxidation state of +4. Its most important property for industrial use is its low neutron absorption cross-section, making it suitable for use inside nuclear reactors.

Uses

The primary use is in zirconium alloys for fuel cladding in nuclear reactors. Because it absorbs neutrons weakly and resists hot water, it is used to clad reactor fuel. Zirconium dioxide (zirconia) is a ceramic material used in dental crowns, replacement joint implants such as artificial hip joints, and heat-resistant materials. Natural zircon mineral is also used in jewelry.

History and Name

The name derives from the zircon mineral, which is related to a Persian word meaning 'golden in color'. The element was recognized in the eighteenth century, but pure metal of good quality was not obtained until later, through the use of advanced separation methods.