The chemical symbol for niobium is "Nb", with an atomic number of 41 and an atomic weight of 92.90638. It belongs to the fifth subgroup (vanadium group) of the periodic system. This is a glossy gray metal with paramagnetism. High purity niobium metal has high ductility, but it becomes harder with increasing impurity content. Niobium has a very low capture cross-section for thermal neutrons, making it quite useful in the nuclear industry.
Niobium metal is stable at room temperature and begins to oxidize to form a dense oxide film at 200 ℃. It can resist the corrosion of molten alkali and various acids, including aqua regia, hydrochloric acid, sulfuric acid, nitric acid, and phosphoric acid.
▲Close up of niobium metal
Physical and chemical properties of tantalum
The chemical symbol for tantalum is "Ta", with an atomic number of 73 and an atomic weight of 180.9479. It belongs to the V subgroup (vanadium group) of the periodic system. It is a silver white metal with a main valence of+5 and excellent corrosion resistance. At temperatures below 200 ℃, it only interacts with fluorine, hydrofluoric acid, strong alkaline solutions, and fuming sulfuric acid. At room temperature, it is not affected by hydrochloric acid, nitric acid, and sulfuric acid, does not interact with aqua regia, and has great stability to acids.
Tantalum is highly ductile and can be pulled into thin filaments to make thin foils. Its coefficient of thermal expansion is very small, with only 0.00066% expansion for every 1 ℃ increase. In addition, it has strong toughness, even better than copper.
Tantalum plays an important role in surgical medicine. It can not only be used to manufacture medical devices, but also is a good "biocompatible material". For example, tantalum sheets can be used to repair skull injuries, tantalum wires can be used to suture nerves and tendons, tantalum strips can replace broken bones and joints, and tantalum yarns or nets made of tantalum wires can be used to compensate for muscle tissue
▲Metal niobium and tantalum coexist in niobium tantalum iron ore
Through research, it has been found that both belong to high melting point metals, with stable chemical properties, compressive and wear-resistant characteristics, and are also excellent superconducting materials. Therefore, they are widely used in various fields and are important strategic resources.