Zirconium ( Zr )
Discovered by Klaproth 1789; .
Zirconium is a lustrous grayish-white metal. Finely-divided metal may ignite spontaneously in air, especially at elevated temperatures, but the solid metal is relatively stable. The metal is extremely corrosion resistant due to the formation of a stable oxide film and is unaffected by acids (with the exception of HF) and alkalis.
As a result of its corrosion resistance, zirconium is widely used in the chemical industry. Also, due to its excellent high temperature properties, coupled with its low neutron absorption, it is used in the construction of nuclear reactors. Zirconium is used as an alloying agent in steel, a getter in vacuum tubes, and as a component in surgical appliances, photoflash bulbs, explosive primers, rayon spinnerets, lamp filaments, etc.
The impure oxide, zirconia, is used for laboratory crucibles that will withstand heat shock, for furnace linings, and by the glass and ceramic industries as a refractory material.