Niobium

Niobium is a tough silver-gray refractory metal with soft texture, high ductility and paramagnetism.
Niobium behaves as a superconductor at low temperature. The critical temperature of niobium at standard atmospheric pressure is 9.22k, the highest of all elemental superconductors. Its magnetic penetration depth is also the highest of all elements. Niobium is one of the three elemental class II superconductors, the other two being vanadium and technetium. The purity of niobium will greatly affect its superconductivity.
Niobium is widely used in the fields of steel, superconducting materials, aerospace thermal protection and structural material, atomic energy structural material, super heat resistant alloy because of its excellent superconductivity, high melting point, corrosion resistance and abrasion resistance.
Generally, high purity niobium and ultra high purity niobium are purified by electron beam evaporation.

Density：8.57 g/cm³
Melting point：2468°C
Boiling point：4742°C
Crystal structure：Body centered cubic
Thermal conductivity：53.7（300K）W·（m·K)^-1
Electrical resistivity (20°C) 13.2μΩ
Coefficient of linear expansion / 7.1×10⁻⁶

Niobium has very stable chemical properties, which can resist all kinds of erosion and form a dense oxide film on the surface at room temperature to prevent further oxidation.
At room temperature, niobium is extremely stable in air, it does not interact with air, it is even not completely oxidized when red hot in oxygen.
At high temperatures, niobium reacts with most nonmetallic elements: with fluorine at room temperature, with chlorine and hydrogen at 200°C, and with nitrogen at 400°C. The products are usually intercalated and not integral compounds.
Although niobium can show all normal oxidation states (from +5 to 1), its most stable valence state is +5. Niobium pentoxide acts like alumina and zinc oxide to protect the metal from corrosion. Niobium pentoxides are mainly used in the production of capacitors, optical glass, etc.
The atoms of niobium are nearly the same size as that of tantalum, and the chemical properties of niobium are very similar to that of tantalum. Although its corrosion-resistance is not so high as that of tantalum, it is cheaper and more common, so it is often used to replace tantalum in less demanding situations.

For superconducting application

Many elements have superconducting properties, of which niobium having the highest critical temperature. The alloy made of niobium, with a critical temperature of 18.5-21 degrees, is the most important superconducting material at present.

High temperature alloy

A large portion of niobium in the world is used in the production of nickel, chromium and iron-based superalloys in the form of pure niobium metal or high purity iron-niobium and nickel-niobium alloys. Niobium forms a γ’ phase in the grain structure of superalloys. Such alloys typically contain up to 6.5% niobium which can be used in jet engines, gas turbines, rocket assemblies, turbochargers and heat-resistant combustion equipment, etc.

Niobium based alloys

C-103 is a niobium alloy, containing 89% niobium, 10% hafnium and 1% titanium, and can be used in liquid rocket propeller nozzle, for example, the main engines of the Apollo lunar module. The Apollo service module use another niobium alloy. Since niobium begins to oxidize above 400°C, a protective coating must be applied to the surface to prevent it from becoming brittle.

For medical application

Niobium plays an important role in surgery, as it can be used not only to make medical devices, but also as a good biocompatible material. Because it has excellent corrosion resistance, will not interact with a variety of liquid substances in the human body, and almost completely does not damage the organism’s tissue, for any sterilization method can be adapted, so can long-term combination with organic tissue and harmless stay in the human body.

Niobium electrolytic capacitor

More than half of Niobium are used to produce solid electrolytic capacitor with large capacity, small size and high stability. The electric capacity of niobium electrolytic capacitor is five times of that of capacitors in same sizes but made from other material. It is very reliable, shock resistant, large operating temperature and long service life. That is wny it is widely used in large quantity in electronic computer, radar, guided missile, supersonic aircraft, automatic controlled device, and electronic circuit of television, etc.

For steel application

Niobium is the most effective microalloying element. The role of niobium is so great that iron atoms are rich in niobium to improve the properties of steel. In fact, adding 0.001% to 0.1% niobium to the steel is enough to change the mechanical properties of the steel. Niobium doesn’t change the structure of iron, but change the microstructure of steel by combination with carbon, nitregon and sulfur. The strengthening effect of niobium on steel is mainly fine grain strengthening and dispersion strengthening. Niobium can form stable carbides and carbonitrides with carbon and nitrogen in steel. Niobium also disperses the carbide and forms a fine crystalline steel.
By addition of niobium, it can not only improve the steel strength, but also the toughness, oxidation resistance at high temperature and corrosion resistance. And it can reduce the transition temperature of steel brittleness, and obtain good welding and forming properties.

• _◎ OD 3.0 ~ 100 mm
• _◎ WT 0.10 ~ 10.0 mm