Zirconium is a chemical element in the modern periodic table that is assigned the symbol Zr and has the atomic number 40. A lustrous gray-white, strong transition metal that resembles titanium, zirconium is obtained chiefly from zircon and is very corrosion resistant. Zirconium is primarily used in nuclear reactors due to its resistance to corrosion and low neutron cross-section.

Notable characteristics

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It is a grayish-white metal, lustrous and exceptionally corrosion resistant. Zirconium is lighter than steel and its hardness is similar to copper. When it is finely divided, the metal can spontaneously ignite in air, especially at high temperatures (it is much more difficult to ignite the solid metal). Zirconium zinc alloy becomes magnetic at temperatures below 35 K. Oxidation states of zirconium include +4, although +3 and +2 can be obtained.

Applications

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The major end uses of zircon (ZrSiO₄) are refractories, foundry sands, and is also used in high strength lacrosse sticks (including investment casting), and ceramic opacification. Zircon is also marketed as a natural gemstone used in jewelry, and its oxide is processed to produce the diamond simulant, cubic zirconia. Other uses:

• Zirconium has a low absorption cross section for thermal neutrons, which makes it ideal for nuclear energy uses, such as cladding fuel elements. More than 90% of zirconium metal production is consumed by commercial nuclear power generation. Modern commercial scale reactors can use as much as a 150,000 meters of zirconium alloy (Zircaloy) tubing. Reactor-grade zirconium has to be purified of hafnium, which has 600 times higher neutron cross-section; a hafnium-free zirconium can be 10 times more expensive than zirconium with naturally occurring 1-5% of hafnium.
• Extensively used by the chemical industry for piping in corrosive environments.
• Zirconium is pyrophoric (flammable) and has been used in military incendiaries such as Dragon's Breath. It is also planned for use in the baseline variant of the AGM-154 Joint Standoff Weapon for incendiary effects.
• Its carbonate was used in poison-ivy lotions until it was evident that many people are allergic. (allergies greatly vary between people)
• Impure zirconium oxide, Zirconia, is used to make laboratory crucibles that can withstand heat shock, for linings of metallurgical furnaces, and by the ceramic and glass industries as a refractory material.
• Human tissues can easily tolerate this metal which makes it suitable for biocompatible implants, eg. some artificial joints and limbs.
• Also used in heat exchangers, as a "getter" in vacuum tubes, in lamp filaments and various specialty alloys.
• When alloyed with niobium, zirconium becomes superconductive at low temperatures and is used to make superconductive magnets with possible large-scale electrical power uses.
• Zirconium Diamide-Diamine complexes can be used to catalyse the polymerisation of alkenes, especially ethene, when activated with Trityl-BArF.
• Zirconium nitride has been used more recently as an alternative to titanium nitride for coating drill bits. Both coatings are supposed to keep the bit sharper and cooler during cutting.
• Bis(cyclopentadienyl)zirconium(IV) chloride hydride (Schwartz's Reagent) is a commercially available metallocene used in the hydrozirconation of alkenes and alkynes.

More on [ Zirconium ]

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