Zirconium alloys exhibit excellent resistance to corrosive attack and works well in many organic and inorganic acids, salt solutions, strong alkalies, and some molten salts. Zirconium owes its
corrosion resistance to the natural formation of a dense, stable, self-healing oxide film on its
surface. Unalloyed zirconium has excellent corrosion resistanc to
sulfuric acid up to 60% concentration at the boiling point and has excellent
corrosion resistance in
hydrochloric acid.
Zirconium is also highly resistant to most alkali solutions up to their boiling point. Zirconium’s
corrosion resistance could be compared with
titanium in many ways; however zirconium is much more robust than titanium in withstanding organic acids, such as
acetic, citric, and
formic acids at various concentration and elevated
temperature.
For all of zirconium’s attributes it still can be corrosively attacked by fluoride ions, wet chlorine, aqua regia, concentrated sulfuric acid above 80% concentration, and ferric or cupric
chlorides.
