Superconducting applications
It has long been discovered that when the temperature drops to near absolute zero, the chemical properties of some substances change abruptly, becoming a "superconductor" with almost no resistance. The temperature at which a substance begins to have this singular "superconducting" property is called the critical temperature. Needless to say, the critical temperature of various substances is not the same.
You know, ultra-low temperatures are hard to come by, and people pay a huge price for them, and the closer you get to absolute zero, the greater the price you have to pay. Therefore, our requirement for superconducting substances is, of course, that the higher the critical temperature, the better.
There are many elements with superconducting properties, and niobium is the one with the highest critical temperature. Alloys made of niobium, with a critical temperature of up to 18.5 to 21 degrees in absolute temperature, are the most important superconducting materials at present.
People once did such an experiment: a metal niobium ring that was cold to a superconducting state, connected with an electric current and then disconnected from the current, and then closed the whole set of instruments to keep the temperature low. Two and a half years later, people turned on the instrument and found that the current in the niobium ring was still flowing, and the current strength was almost exactly the same as when the electricity was first applied!
From this experiment, it can be seen that superconducting materials lose almost no current. If you use a superconducting cable to transmit electricity, because it has no resistance, there will be no energy loss when the current passes through, so the transmission efficiency will be greatly improved.
Someone has designed a high-speed maglev train, which has superconducting magnets installed on its wheels, so that the whole train can float on the track for about ten centimeters. In this way, there is no more friction between the train and the track, reducing the resistance to move forward. A maglev train carrying 100 people can reach a speed of more than 500 kilometers per hour with only 100 horsepower.
With a 20-kilometer-long niobium-tin belt, wound around a wheel flange with a diameter of 1.5 meters, the windings are able to generate a strong and stable magnetic field, enough to lift a weight of 122 kilograms and levitate it in the magnetic field space. If this magnetic field were to be used in a thermonuclear fusion reaction, and the powerful thermonuclear fusion reaction could be controlled, it would be possible to provide us with a large and almost endless supply of cheap electricity.
A direct current generator was once made of niobium-titanium superconducting material. It has many advantages, such as small size, light weight, low cost, and it generates a hundred times more electricity than ordinary generators of the same size.
Superalloys
A large part of the world's niobium is used in the pure metal state or in the form of high-purity ferroniobium and niobium-nickel alloys for the production of nickel, chromium and iron-based superalloys. These alloys are used in jet engines, gas turbine engines, rocket components, turbochargers, and heat-resistant combustion equipment. Niobium forms 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 niobium-containing nickel-based alloys with 50% nickel, 18.6% chromium, 18.5% iron, 5% niobium, 3.1% molybdenum, 0.9% titanium and 0.4% aluminum. Applications include being used as a high-end airframe material, such as the Gemini program.
Niobium-based alloys
C-103 is a niobium alloy that contains 89% niobium, 10% hafnium, and 1% titanium, and can be used in liquid rocket thruster nozzles, such as the main engine of the 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 its surface to prevent it from becoming brittle.
Medical applications
Niobium also occupies an important position in surgical treatment, it can not only be used to manufacture medical devices, but also is a good "biological adaptation material", because it has excellent corrosion resistance, will not interact with various liquid substances in the human body, and almost completely does not damage the body tissues of organisms, can be adapted to any sterilization method, so it can be combined with organic tissues for a long time and stay harmlessly in the human body.