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» Niobium Corrosion Resistance

The corrosion resistance of niobium is more limited than tantalum and this must be taken into consideration. The limitation stems from its sensitivity to most alkalis and certain strong oxidants.

Niobium is totally resistant to such highly corrosive media as wet or dry chlorine, bromine, saturated brines, ferric chloride, hydrogen sulfide, and sulfur dioxide as well as nitric and chromic acids. It is also resistant to sulfuric and hydrochloric acids within specific temperature and concentration limits.

Niobium is also resistant to attack by many liquid metals such as: Li <1000°C, Na, K + NaK <1000°C, ThMg <850°C, U <1400°C, Zn <450°C, Pb <850°C, Bi <500°C and Hg <600°C.

Niobium has the ability to form stable, passive oxides and therefore, it can provide unique solutions to many corrosion problems. However, niobium cannot be used in air at temperatures exceeding 200°C.

Media	Concentration	Temp.	Nb
Acetic Acid	50%	Boiling	Nil
Bromine	Dry	200°F	Nil
Chlorine	Wet	220°F	Nil
Chromic Acid	50%	Boiling	1 mpy
Hydrochloric Acid	5%	200°F	1 mpy
	30%	200°F	5 mpy
Nitric Acid	65%	Boiling	<2 mpy
Sodium Hydroxide	10%	Room	*
Sulfuric Acid	40%	Boiling	20 mpy
	98%	Boiling	attacked

*Material may become brittle due to hydrogen attack

However, niobium is totally resistant to such highly corrosive media as wet or dry chlorine, bromine, saturated brines, ferric chloride, hydrogen sulfide, and sulfur dioxide as well as nitric and chromic acids. It is also resistant to sulfuric and hydrochloric acids within specific temperature and concentration limits.

Niobium is also resistant to attack by many liquid metals such as: Li <1000°C, Na, K + NaK <1000°C, ThMg <850°C, U <1400°C, Zn <450°C, Pb <850°C, Bi <500°C and Hg <600°C.

Niobium has the ability to form stable, passive oxides and therefore, it can provide unique solutions to many corrosion problems. However, niobium cannot be used in air at temperatures exceeding 200°C. Refer to the table entitled Corrosion Resistance for additional information.