Introduction of Tantalum Metal

Tantalum, the metallic element, is found mainly in tantalite and issymbiotic with niobium. Tantalum is moderately hard, ductile and can be drawn into thin foils in the form of filaments. Its coefficient of thermal expansion is very small. Tantalum has excellent chemical propertiesand is extremely resistant to corrosion. Although tantalum is highly resistant to corrosion, its resistance to corrosion is due to a stable protective film of tantalum pentoxide  (Ta2O5) on the surface. It does not react to hydrochloric acid,concentrated nitric acid or "aqua regia", either under cold or hot conditions. It can be used in the manufacture of hair-dropping utensils, as well as in electrodes for electronic tubes, rectifiers and electrolytic capacitors. It is used medically to make thin sheets or threads to mend damaged tissue.

Tantalum also has excellent chemical properties and is extremely resistant to corrosion, both in cold and hot conditions, and does not react to hydrochloric acid,concentrated nitric acid or "Aqua regia". In addition, tantalum dissolves rapidly in a mixture of hydrofluoric and nitric acids, and can also be dissolved in oxyfluoric acid. However, tantalum is more afraid of strong bases and will be rapidly dissolved in a caustic soda solution at 110 degrees and 40%, and in a solution of potassium hydroxide at the same concentration, it will be rapidly dissolved at 100 degrees. Except in the cases described above, inorganic salts in general cannot corrode tantalum below 150 degrees Celsius.Experiments have shown that tantalum does not react at room temperature to alkaline solutions, chlorine gas, Australian water, dilute sulphuric acid and many other agents, but only under the action of hydrofluoric acid and hot concentrated sulphuric acid. Such a situation is relatively rare among metals.