The application of niobium

It has long been known that when temperatures drop to near absolute zero, some substances undergo a sudden chemical change, becoming a kind of "superconductor" with almost no electrical resistance. The temperature at which matter begins to possess this strange "superconducting" property is called the critical temperature. Needless to say, the critical temperature of various substances is different.

You know, ultra-low temperatures are not easy to get, and people pay a huge price for them. The closer you get to absolute zero, the more you have to pay. So our requirement for superconducting materials, of course, is that the critical temperature is as high as possible.

Many elements with superconductivity, niobium is one of the highest critical temperature. Alloys made of niobium, with critical temperatures as high as 18.5 to 21 degrees absolute, are the most important superconducting materials available.

In one experiment, a ring of niobium, cold enough to be superconducting, was turned on and off by an electric current, and then the whole apparatus was sealed and kept cold. Two and a half years later, when the instrument was turned on, the current in the ring was still flowing, and almost as strong as when it was first energized!

As can be seen from this experiment, superconducting materials lose little current. If a superconducting cable is used to transmit electricity, the transmission efficiency will be greatly improved because there is no resistance and no energy loss when the current passes through.

A high-speed maglev train has been designed with superconducting magnets in its wheels that allow the train to float about 10 centimeters above the track. In this way, there is no more friction between the train and the track, reducing drag forward. A maglev train with 100 passengers can reach speeds of more than 500 kilometers per hour with only 100 horsepower of propulsion.

Using a 20-kilometer-long niobium-tin strip wrapped around the rim of a wheel 1.5 meters in diameter, the windings generate a strong and stable magnetic field, enough to lift a weight of 122 kilograms and keep it suspended in magnetic space. If this magnetic field could be harnessed to a thermonuclear reaction, bringing the powerful thermonuclear reactions under control, it would be possible to provide us with an almost endless supply of cheap electricity.

Not long ago, a direct current generator was made of niobium-titanium superconducting material. It has many advantages, such as small size, light weight, low cost, compared with the same size of the ordinary generator, it can produce a hundred times more electricity.

High temperature alloy

A large portion of the world's niobium is used in the production of nickel, chromium and iron based superalloys as pure metal or as high-purity niobium and niobium alloys. These alloys can be used in jet engines, gas turbine engines, rocket components, turbochargers and heat-resistant combustion devices. Niobium forms γ "phase in the grain structure of superalloy. Such alloys generally contain up to 6.5% niobium. Inconel 718 alloy is a niobium-based alloy containing 50% nickel, 18.6% chromium, 18.5% iron, 5% niobium, 3.1% Molybdenum, 0.9% titanium and 0.4% aluminum. Applications include high-end airframe materials such as those used in project Gemini.

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

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

For example, niobium sheets can be used to repair damage to the skull, niobium wire can be used to suture nerves and tendons, niobium strips can replace broken bones and joints, niobium yarn or net made of niobium wire can be used to compensate muscle tissue...

In hospitals, tantalum rods are used to replace broken bones in the human body, and over time, muscles grow on the niobium rods just as they do on real bones. No wonder niobium is called a "biophilic metal".

Why does niobium play such a strange role in surgery?

The key is because it has excellent corrosion resistance, will not act with a variety of liquid substances in the human body, and almost completely does not damage the organism tissue, for any sterilization method can adapt, so it can be combined with organic tissue for a long time and harmlessly stay in the human body.

In addition to such good use in surgery, niobium and tantalum can be used to make electrolytic capacitors, rectifiers and so on, using their chemical stability.

More than half of niobium, in particular, is used to produce solid electrolytic capacitors with large capacity, small volume and high stability. Hundreds of millions of them are produced worldwide each year.

Niobium electrolytic capacitor does not "live up to" people's expectations, it has many advantages compared with other materials.

It has five times more capacity than other capacitors of the same size, and is very reliable, shockproof, working temperature range, long service life, has been widely used in electronic computers, radar, missiles, supersonic aircraft, automatic control devices and color TELEVISION, three-dimensional television and other electronic circuits. Waste niobium is the most effective microalloying element among various microalloying elements in steel. The effect of niobium is so great that it can improve the properties of steel if there are abundant niobium atoms in iron atoms. In fact, the addition of 0.001%-0.1% niobium to steel is enough to change the mechanical properties of steel. For example, when 0.1% alloying element is added, the yield strength of steel is improved in order: niobium 118MPa; Vanadium 71.5 MPa; Molybdenum 40 mpa; Manganese 17.6 MPa; Titanium is zero. In practice, the yield strength of steel can be increased by more than 30% only by adding 0.03%-0.05%Nb. Steel costs only $1 a tonne more. For example: the yield strength of ordinary carbon steel is generally 250MPa, adding trace niobium can improve the strength to 350-800mpa.

The addition of niobium as a microalloyed element does not change the structure of iron, but changes the microstructure of steel by combining with carbon nitrogen sulfur in steel. 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. Moreover, carbides can be dispersed to form steels with fine crystallization.

Niobium can also induce precipitation and control the cooling rate to realize the dispersion of precipitates. Adjust the toughness level of steel in a wide range. Therefore, the addition of niobium can not only improve the strength of steel, but also improve the toughness, high temperature oxidation resistance and corrosion resistance of steel! Reduce the brittle transition temperature of steel to obtain good welding performance and forming performance, the composition is widely used in coiled tubing tubing material.