ABSTRACT
Zirconium and hafnium are hard corrosion-resistant metals. Zirconium is always associated with 1"-4" hafnium in its minerals because their geochemical properties are nearly identical so that they are not differentiated in geological processes. Zirconium and hafnium both have electron configurations with four valence electrons outside the penultimate filled shell and similar atomic and ionic radii. The outstanding resistance of zirconium and hafnium in aqueous media is due to the formation of passive surface films based on their oxides. Zirconium and hafnium are produced primarily for applications in the generation of nuclear power which considers some corrosion issues in materials' selection for the prevailing environments in nuclear reactors. Zirconium could not be considered an economic choice for corrosion resistance until it was produced on an industrial scale for nuclear applications. Applications for which zirconium is especially suitable include plants handling hydrochloric acid and dry but not wet chlorine.
