Compatibility of Niobium With Furnace Construction Materials
In all high-temperature applications, the behaviour of niobium in gas atmospheres and in contact with furnace materials has to be considered.
This is very important because undesirable reactions at high temperatures may take place which can damage the niobium furnace components.
Even in high vacuum, undesirable reactions between niobium and traces of evolved gases may occur. These can result from the outgassing of the material being heat treated, leakages or improper operations of the vacuum equipment.
Noble gases can be used as protective atmospheres, provided they are of sufficient purity.
Oxygen and air react strongly with niobium at elevated temperatures. Dissolved oxygen can be removed from niobium by annealing in high vacuum above 1600℃. The outgassing of oxygen is always combined with a loss of material, because the oxides evaporate and condense in cool areas of the vacuum chamber.
Niobium usually absorbs large quantities of hydrogen and nitrogen at higher temperatures and becomes very brittle. However, hydrogen can be outgassed from niobium at temperatures above 300℃.
With reactions between niobium and polyatomic gases, the gas molecules are decomposed on the niobium surface before reactions with niobium take place.
Niobium reacts with ammonia; the nitrogen atoms diffusing into the niobium to form nitrides. The reaction with water vapour at high temperatures causes oxidation.
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This is very important because undesirable reactions at high temperatures may take place which can damage the niobium furnace components.
Even in high vacuum, undesirable reactions between niobium and traces of evolved gases may occur. These can result from the outgassing of the material being heat treated, leakages or improper operations of the vacuum equipment.
Noble gases can be used as protective atmospheres, provided they are of sufficient purity.
Oxygen and air react strongly with niobium at elevated temperatures. Dissolved oxygen can be removed from niobium by annealing in high vacuum above 1600℃. The outgassing of oxygen is always combined with a loss of material, because the oxides evaporate and condense in cool areas of the vacuum chamber.
Niobium usually absorbs large quantities of hydrogen and nitrogen at higher temperatures and becomes very brittle. However, hydrogen can be outgassed from niobium at temperatures above 300℃.
With reactions between niobium and polyatomic gases, the gas molecules are decomposed on the niobium surface before reactions with niobium take place.
Niobium reacts with ammonia; the nitrogen atoms diffusing into the niobium to form nitrides. The reaction with water vapour at high temperatures causes oxidation.
Zhengzhou Sanhui Co., Ltd has been dealing with refractory metals for almost 25 years. We are one Alibaba 10-year golden supplier. Come to us for tungsten, titanium, zirconium and other metal products.
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