Application of niobium

applied superconductivity

It has long been found that when the temperature drops to near absolute zero, the chemical properties of some substances will change suddenly and become a kind of "superconductor" with almost no resistance. The temperature at which matter begins to possess this strange superconductivity is called the critical temperature. Needless to say, the critical temperatures of various substances are different .

We should know that ultra-low temperature is very difficult to obtain, and people have paid a huge price for it; the closer to absolute zero, the greater the cost. So our requirement for superconductors, of course, is that the higher the critical temperature, the better.

There are many elements with superconductivity, among which niobium is the highest. The critical temperature of niobium alloy is as high as 18.5-21 ℃, which is the most important superconducting material at present.

People have done such an experiment: a metal niobium ring cold to superconducting state, connected with the current, and then cut off the current, and then closed the whole set of instruments to keep low temperature. Two and a half years later, the instrument was turned on, and it was found that the current in the niobium ring was still flowing, and the current intensity was almost the same as when it was just electrified!

It can be seen from this experiment that the superconductor can hardly lose current. If the superconducting cable is used for power transmission, because it has no resistance, there will be no energy loss when the current passes through, so the transmission efficiency will be greatly improved.

Some people have designed a kind of high-speed maglev train. Its wheels are equipped with superconducting magnets, so that the whole train can float on the track about 10 cm. In addition, there is no friction between the train and the track. A maglev train carrying 100 passengers can reach a speed of more than 500 kilometers per hour with only 100 horsepower.

A 20 kilometer long niobium tin strip is wound on the rim with a diameter of 1.5 meters. The winding can produce a strong and stable magnetic field, which is enough to lift 122 kilograms of weight and suspend it in the magnetic field space. If this kind of magnetic field is used in thermonuclear fusion reaction and the strong thermonuclear fusion reaction is controlled, it is possible to provide us with a large amount of almost endless cheap power.

Not long ago, a DC generator was made of niobium titanium superconductor. It has many advantages, such as small size, light weight and low cost. Compared with ordinary generators of the same size, it generates 100 times more electricity. [3] 

Superalloy

A large part of niobium in the world is used in the production of nickel, chromium and iron-based superalloys in the form of pure metal or high-purity ferroniobium and niobium nickel alloys. These alloys can be used in jet engines, gas turbine engines, rocket components, turbochargers and heat-resistant combustion equipment. Niobium will form a "γ" phase in the grain structure of superalloys. These alloys generally contain up to 6.5% niobium. Inconel 718 Alloy is one of the nickel base alloys containing niobium, with the contents of nickel 50%, chromium 18.6%, iron 18.5%, niobium 5%, molybdenum 3.1%, titanium 0.9% and aluminum 0.4%, respectively. Applications include as high-end body materials, such as those used in Gemini program.

C-103 is a niobium alloy containing 89% niobium, 10% hafnium and 1% titanium. It can be used in liquid rocket thruster nozzles, such as the main engine of Apollo lunar module. The Apollo service module uses another niobium alloy. Since niobium begins to oxidize above 400 ° C, a protective coating must be applied to prevent it from becoming brittle.

Niobium based alloy

C-103 alloy is a niobium alloy developed by Huachang company and Boeing company in the early 1960s. Due to the cold war and space race, many American companies, such as DuPont, United carbide and general electric, are developing niobium based alloys at the same time. Niobium reacts easily with oxygen, so the production process needs to be carried out in vacuum or inert gas environment, which greatly increases the cost and difficulty. Vacuum arc remelting (VaR) and electron beam melting (EBM) were the most advanced production processes at that time, which promoted the development of various niobium alloys. Since 1959, a total of 256 niobium alloys have been tested in the "c-series" (which may have taken the initials of the old name "columbium") and finally produced C-103. These alloys can be melted into granular or flaky shape. Huachang had hafnium extracted from nuclear grade zirconium alloy and hoped to develop its commercial application. Nb-10hf-1ti alloy with so-called 103 component ratio in c-series has the best balance between malleability and high-temperature properties. Therefore, Huachang produced the first batch of 500 LB C-103 alloy by VaR and EBM method in 1961, which was applied to turbine engine parts and liquid metal heat exchanger. Other niobium alloys in the same period include: fs85 (nb-10w-28ta-1zr) of fenstell metallurgical company, cb129y (nb-10w-10hf-0.2y) of Huachang and Boeing, cb752 (nb-10w-2.5zr) of combined carbide and nb1zr of superior pipeline company.

Medical applications

Niobium also plays an important role in surgery. It can not only be used to manufacture medical devices, but also is a good "biocompatible material".

For example, the use of niobium can make up for the damage of the skull, niobium wire can be used to suture nerves and tendons, niobium strip can replace broken bones and joints, and niobium yarn or mesh made of niobium wire can be used to compensate for muscle tissue