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Location of niobium. Properties of niobium

In ancient Greek. mythology * a. niobium; n. Niob, Niobium; f. niobium; And. niobio), is a chemical element of group V of the periodic system of Mendeleev, atomic number 41, atomic mass 92.9064. It has one natural isotope 93 Nb.

Niobium oxide was first isolated by the English chemist C. Hatchet in 1801 from columbite. Metallic niobium was obtained in 1866 by the Swedish scientist K. V. Blomstrand.

Niobium properties

Niobium is a steel-colored metal, has a body-centered cubic lattice with a = 0.3294 nm; density 8570 kg/m3; melting temperature 2500°С, boiling temperature 4927°С; heat capacity (298 K) 24.6 J/(mol.K); thermal conductivity (273 K) 51.4 W/(m.K); temperature coefficient of linear expansion (63-1103 K) 7.9.10 -6 K -1 ; electrical resistivity (293 K) 16.10 -8 Ohm.m; thermal coefficient of electrical resistance (273 K) 3.95.10 -3 K -1. The transition temperature to the superconducting state is 9.46 K.

Oxidation state +5, less often from +1 to +4. Its chemical properties are close to tantalum, extremely resistant to cold and, with slight heating, to the action of many aggressive environments, incl. and acids. Niobium is dissolved only by hydrofluoric acid, its mixture with nitric acid and alkali. Amphoteric. When interacting with halogens, it forms niobium halides. When Nb 2 O 5 is fused with soda, salts of niobic acids are obtained - niobates, although the acids themselves do not exist in a free state. Niobium can form double salts and complex compounds. Non-toxic.

Receipt and use

To obtain niobium, niobium concentrate is fused with caustic soda or soda and the resulting alloy is leached. The Nb and Ta contained in the undissolved precipitate are separated, and niobium oxide is reduced separately from tantalum oxide. Compact niobium is produced by powder metallurgy, electric arc, vacuum and electron beam melting.

Niobium is one of the main components in alloying heat-resistant steels and alloys. Niobium and its alloys are used as structural materials for parts of jet engines, rockets, gas turbines, chemical equipment, electronic devices, electrical capacitors, and superconducting devices. Niobates are widely used as ferroelectrics, piezoelectrics, and laser materials.

The production of niobium along with tantalum, as well as tantalonium-obium alloys, is of great economic importance from the point of view of the integrated use of both valuable metals.
In many cases, instead of tantalum, with the same effect, you can use niobium, which is similar in properties, or alloys of tantalum with niobium, since these metals form a continuous series of solid solutions, the properties of which are close to the properties of the original metals.
An alloy of tantalum with niobium can be obtained by mixing separately obtained tantalum and niobium powders, followed by pressing the mixture and sintering in a vacuum, as well as by simultaneous joint reduction of a mixture of tantalum and niobium compounds, for example, a mixture of complex fluorides K2TaF7 and K2NbF7, a mixture of chlorides, a mixture of oxides, etc. . P.
Typically, when using the hydrofluoric acid method for separating tantalum and niobium, the latter is separated in the form of fluoroxyniobate K2NbOF5*H2O.
This salt is not suitable for reduction with sodium for two reasons:
a) water of crystallization, which is part of the said salt, reacting with sodium can lead to an explosion,
b) oxygen, which is part of the salt and associated with niobium, is not reduced by sodium and remains in the form of an oxide impurity in the reduction product.
Therefore, potassium fluoroxyniobate must be recrystallized through a solution of hydrofluoric acid with a HF concentration above 10%, resulting in the formation of the K2NbF7 salt, suitable for reduction with sodium.
Niobium can also be produced by electrolysis under conditions similar to those described for tantalum production. A lower current efficiency is noted than in the electrolytic production of tantalum, as well as difficulties associated with the noticeable solubility of niobium compounds of different valencies in the electrolyte.
Electrolysis is also possible from a mixed bath containing a mixture of Ta2O5 + Nb2O5 as decomposing components and K2TaF7 as a solvent. In this case, an alloy of niobium with tantalum is obtained.
To obtain niobium, a method of carbon reduction of niobium pentoxide in vacuum was proposed.

Reduction of niobium pentoxide with carbon

To obtain niobium, K. Bohlke developed a method for the reduction of niobium pentoxide with niobium carbide in vacuum according to the reaction:

Essentially this process comes down to the reduction of niobium pentoxide with carbon.
Due to the high chemical strength of niobium pentoxide, reduction with carbon at atmospheric pressure requires high temperature (about 1800-1900°), which can be obtained in a graphite tube furnace. Niobium has a high affinity for carbon (free energy of formation of niobium carbide -ΔF° = 38.2 kcal ), therefore, in the presence of carbon gases in the furnace and at a high rate of diffusion in the solid phase, developing at such a high temperature, niobium turns out to be contaminated with niobium carbide, even if the charge is prepared based on the reaction

In a vacuum, the reduction reaction with carbon occurs at a lower temperature (1600-1700°),
Briquettes are prepared from a mixture of niobium pentoxide and soot, taken in stoichiometric ratios based on the reaction

Rolling is carried out at 1800-1900° in a graphite tube furnace in a protective atmosphere (hydrogen, argon) or in a vacuum at a temperature of 1600° until the evolution of CO ceases. The resulting product is slightly sintered briquettes consisting of particles of powdered gray carbide. The carbide is ground into powder in a ball mill and mixed with pentoxide in ratios corresponding to reaction (1). Briquettes of the Nb2O5 + NbC mixture are again calcined in vacuum at a temperature of about 1600°.
To ensure the removal of carbon in the form of CO, a small excess of niobium pentoxide should be added to the Nb2O5 + NbC mixture. In the subsequent operation of high-temperature sintering (welding) of bars pressed from powdered metal niobium, excess niobium pentoxide is removed, since niobium oxides (like tantalum) volatilize in a vacuum at a temperature below the melting point of the metal
Due to the inevitable time spent on creating a vacuum and cooling the product in it, the productivity of a vacuum furnace in the production of initial niobium carbide is much lower than the productivity of a graphite tube furnace operating at atmospheric pressure, in which a continuous process can be carried out by moving cartridges with briquettes of a mixture of Nb2O5 + C. Therefore, it is more expedient to obtain NbC continuously in a graphite tube furnace at atmospheric pressure, although at temperatures of 1800-1900°.
It would be possible to obtain metallic niobium in a vacuum furnace directly by reacting pentoxide with soot according to reaction (2) with a slight excess of Nb2O5 in the charge. However, when loading a mixture of Nb2O5 + 5NbC into a vacuum furnace, its productivity increases significantly compared to loading a mixture of Nb2O5 + 5C, since the Nb2O5 + SNbC mixture contains niobium (82.4%) 1.5 times more than the Nb2O5 + 5C mixture ( 57.2%) In addition, the first mixture has an additive specific gravity 1.7 times greater than the second mixture (6.25 g/cm3 and 3.7 g/cm3, respectively).
In addition, it must be taken into account that niobium carbide, which makes up the predominant part of the Nb2O5 + 5NbC mixture, is coarser-grained than dispersed Nb2O5 and soot powders, which is an additional reason for the greater bulk weight of the Nb2O5 + 5NbC mixture than the Nb2O5 + 5C mixture.
As a result of all this, a unit volume of the cartridge can accommodate 2.5-3 times more material (based on niobium content) in the form of briquettes of the Nb2O5 + 5NbC mixture than briquettes of the Nb2O5 + 5C mixture.
Bolke's work does not provide sufficiently strong evidence for the need to strictly adhere to his recommended composition of the Nb2O5 + 5NbC mixture loaded into a vacuum furnace.
By calcining a mixture of Nb2O5 + 5C in a coal-tube furnace at atmospheric pressure, a product similar in composition to metallic niobium with a small admixture of carbon can be obtained with high productivity (in a continuous process). This niobium-rich powder with high specific and bulk gravity can then be mixed with an appropriate amount of Nb2O5 (with a slight excess of Nb2O5 relative to the equivalent carbon impurity content of the niobium) and the briquetted mixture calcined in a vacuum oven to remove carbon in the form of CO.
With this option, the capacity, and therefore the productivity, of the vacuum furnace will be greatest. The small remaining excess Nb2O5 will evaporate during further high-temperature sintering of niobium, and the latter will turn into a compact malleable metal
When using low-carbon niobium instead of niobium carbide to react with pentoxide, some technological complications may arise. The fact is that when producing low-carbon niobium at atmospheric pressure in the reaction space of a graphite-tube furnace, the presence of nitrogen impurities from the air that can enter the furnace is always possible. Niobium, having a high affinity for nitrogen, actively absorbs it. When producing niobium carbide, the possibility of contamination of the product with nitrogen is much less due to the greater affinity of niobium for carbon than for nitrogen.
Therefore, the production of metallic niobium when using low-carbon niobium as a starting material is complicated by the need to create conditions that exclude the possibility of nitrogen entering the reaction space, which is difficult to achieve in a graphite tube furnace freely connected to the atmosphere. To remove nitrogen from the furnace, it is necessary to carefully fill the furnace with pure hydrogen or argon, maintain the tightness of the casing, avoid drawing air into the reaction tube when loading cartridges with a mixture of Nb2O5 + 5C into it and when unloading niobium, etc.
Therefore, the question of the advantages of the option of preliminary production of niobium carbide or low-carbon niobium at atmospheric pressure (followed by calcination of these products in a mixture with Nb2O5 in a vacuum) can be resolved by practical possibilities in each individual case.
The advantages of the niobium carbon reduction process according to one of the described options are: the use of a cheap reducing agent in the form of soot and high direct extraction of niobium into the finished metal
The similarity of the properties of tantalum and niobium oxides allows the described method to be used to obtain malleable tantalum.

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A chemical element named after the ancient Niobe, a woman who dared to laugh at the gods and paid for it with the death of her children. Niobium represents humanity's transition from industrial to digital production; from steam locomotives to rocket launchers; from coal-fired power plants to nuclear power. The global price of niobium per gram is quite high, as is the demand for it. Most of the latest scientific achievements are closely related to the use of this metal.

Niobium price per gram

Since the main uses of niobium are related to nuclear and space programs, it is classified as a strategic material. Recycling is much more financially profitable than the development and extraction of new ores, which makes niobium in demand in the secondary metal market.

The price for it is determined by several factors:

Metal purity. The more foreign impurities, the lower the price.
Delivery form.
Scope of delivery. Directly proportional to metal prices.
Location of the scrap collection point. Each region has a different need for niobium and, accordingly, its price.
Presence of rare metals. Alloys containing elements such as tantalum, tungsten, molybdenum are higher in price.
The meaning of quotes on world exchanges. These values are the basis for setting prices.

Indicative overview of prices in Moscow:

Niobium NB-2. The price varies between 420-450 rubles. per kg.
Niobium shavings. 500-510 rub. per kg.
Niobium stack NBSh00. Differs in increased prices due to the insignificant content of impurities. 490-500 rub. per kg.
Niobium rod NBSh-0. 450-460 rub. per kg.
Niobium NB-1 in the form of a rod. The price is 450-480 rubles. per kg.

Despite the high cost, the demand for niobium in the world continues to grow. This happens due to its enormous potential for use and the shortage of metal. There are only 18 grams of niobium per 10 tons of soil.

The scientific community continues to work to find and develop a substitute for such an expensive material. But so far I have not received a concrete result in this. This means that the price of niobium is not expected to fall in the near future.

To regulate prices and increase the speed of turnover, the following categories are provided for niobium products:

Niobium ingots. Their size and weight are standardized by GOST 16099-70. Depending on the purity of the metal, they are divided into 3 grades: niobium NB-1, niobium NB-2 and, accordingly, niobium NB-3.
Niobium staff. It has a higher percentage of foreign impurities.
Niobium foil. Manufactured in thicknesses up to 0.01 mm.
Niobium rod. According to TU 48-4-241-73 it is supplied in the grades NbP1 and NbP2.

Physical properties of niobium

The metal is gray with a white tint. Belongs to the group of refractory alloys. The melting point is 2500 ºС. Boiling point 4927 ºС. Differs in the increased value of heat resistance. Does not lose its properties at operating temperatures above 900 ºС.

Mechanical characteristics are also at a high level. The density is 8570 kg/m3, with the same indicator for steel being 7850 kg/m3. Resistant to operation under both dynamic and cyclic loads. Tensile strength - 34.2 kg/mm2. Has high plasticity. The relative elongation coefficient varies between 19-21%, which makes it possible to obtain rolled niobium sheets up to 0.1 mm thick from it.

Hardness is related to the purity of the metal from harmful impurities and increases with their composition. Pure niobium has a Brinell hardness rating of 450.

Niobium lends itself well to pressure treatment at temperatures below -30 ºС and is difficult to cut.

Thermal conductivity does not change significantly with large temperature fluctuations. For example, at 20 ºС it is 51.4 W/(m K), and at 620 ºС it increases by only 4 units. Niobium competes in electrical conductivity with elements such as copper and aluminum. Electrical resistance - 153.2 nOhm m. Belongs to the category of superconducting materials. The temperature at which the alloy enters the superconductor mode is 9.171 K.

Extremely resistant to acidic environments. Such common acids as sulfuric, hydrochloric, orthophosphoric, nitric do not affect its chemical structure in any way.

At temperatures above 250 ºС, niobium begins to be actively oxidized by oxygen, and also enter into chemical reactions with hydrogen and nitrogen molecules. These processes increase the fragility of the metal, thereby reducing its strength.

Does not apply to allergenic materials. Introduced into the human body, it does not cause a rejection reaction by the body.
It is a metal of the first group of weldability. The welds are tight and do not require preparatory operations. Resistant to cracking.

Types of alloys

Based on the value of mechanical properties at elevated temperatures, niobium alloys are divided into:

Low strength. They operate within the range of 1100-1150 ºС. They have a simple set of alloying elements. This mainly includes zirconium, titanium, tantalum, vanadium, hafnium. Strength is 18-24 kg/mm2. After passing the critical temperature threshold, it drops sharply and becomes similar to pure niobium. The main advantage is high plastic properties at temperatures up to 30 ºС and good workability under pressure.
Medium strength. Their operating temperature is in the range of 1200-1250 ºС. In addition to the above alloying elements, they contain impurities of tungsten, molybdenum, and tantalum. The main purpose of these additives is to preserve mechanical properties with increasing temperature. They have moderate ductility and can be easily processed under pressure. A striking example of an alloy is niobium 5VMC.
High strength alloys. Used at temperatures up to 1300 ºС. With short-term exposure up to 1500 ºС. They differ in their chemical composition of higher complexity. 25% consist of additives, the main share of which is tungsten and molybdenum. Some types of these alloys are characterized by a high carbon content, which has a positive effect on their heat resistance. The main disadvantage of high-strength niobium is low ductility, which makes processing difficult. And, accordingly, obtaining industrial semi-finished products.

It should be noted that the categories listed above are of a conditional nature and give only a general idea of the method of using a particular alloy.

Also worth mentioning are compounds such as ferroniobium and niobium oxide.

Ferroniobium is a compound of niobium with iron, where the content of the latter is at the level of 50%. In addition to the main elements, it includes hundredths of titanium, sulfur, phosphorus, silicon, and carbon. The exact percentage of elements is standardized by GOST 16773-2003.

Niobium pentaxide is a white crystalline powder. Not susceptible to dissolution in acid and water. It is produced by burning niobium in an oxygen environment. Completely amorphous. Melting point 1500 ºС.

Applications of niobium

All of the above properties make the metal extremely popular in various industries. Among the many ways to use it, the following positions are distinguished:

Used in metallurgy as an alloying element. Moreover, both ferrous and non-ferrous alloys are alloyed with niobium. For example, adding just 0.02% of it to stainless steel 12Х18Н10Т increases its wear resistance by 50%. Aluminum improved with niobium (0.04%) becomes completely impervious to alkali. Niobium acts on copper as a hardening agent on steel, increasing its mechanical properties by an order of magnitude. Note that even uranium is doped with niobium.
Niobium pentoxide is the main component in the manufacture of highly refractory ceramics. It has also found application in the defense industry: armored glass of military equipment, optics with a large refractive angle, etc.
Ferroniobium is used to alloy steels. Its main task is to increase corrosion resistance.
In electrical engineering they are used for the manufacture of capacitors and current rectifiers. Such capacitors are characterized by increased capacitance and insulation resistance, and small sizes.
Compounds of silicon and germanium with niobium are widely used in the field of electronics. Superconducting solenoids and elements of current generators are made from them.

Niobium (Nb) is a rare, soft, transition metal used in the production of high quality steel. Niobium is a component for the production of alloys, which, when added to other materials, significantly improves their properties. Steel containing niobium has many attractive properties that make it highly desirable for use in the automotive, construction and gas pipeline industries. Steel with added niobium is harder, lighter and more resistant to corrosion.

Reserves at niobium deposits in 2012, thousand tons *

* US Geological Survey data

Pyrochlore-containing ores are mined using two main methods - in isolation or as a combination. Open pit mining is a common method in Brazil, while underground mining is used at the Niobec mine in Canada. However, the Niobec mine in Canada plans to use two mass mining methods - open pit and underground - as they have the potential to significantly increase plant capacity and production volumes while reducing operating costs.
Once the ore is mined, it is crushed into fine particles and processed through flotation and magnetic separation to remove the iron. In Canada, nitric acid is used to remove apatite, while in Brazil a special process is used to remove barium, phosphorus and sulfur. The result of this physical treatment is a pyrochlore concentrate with a Nb2O5 content of 55-60%. Most of the pyrochlore concentrate is processed into standard grade ferroniobium for use in industrial applications where impurities are tolerated. For applications requiring higher levels of purity, post-processing is required to bring the niobium to ~99% purity levels, such as vacuum grade niobium oxide or ferroniobium purity levels.

* US Geological Survey data

Global demand for niobium grew at an average annual rate of 10% between 2000 and 2010. Growth was driven by two key factors:
1. Stable demand for steel, especially among steel producers from the BRICS countries. Demand in these countries grew by 14% in 2010 to 1.414 million tonnes and is estimated to have increased by a further 4% in 2011.
It should be noted that the automotive, construction and oil and gas sectors, which are the largest consumers of ferroniobium, tend to be highly correlated with economic growth, and the state of the global economy has the greatest impact on niobium demand.
The strong GDP growth of the BRICS countries requires more steel and, accordingly, determines higher demand for niobium in steel production. World GDP increased by 5.1% in 2010, mainly due to the strong performance of the BRIC economies, which grew by 8.8% in 2010, especially China, which grew by 10.3%. GDP growth in the BRICS countries in 2011 and 2012 was also high: 4-10% against the backdrop of global economic growth of ~3-4%. Over the past decade, the BRICS countries have defined the global economic landscape, accounting for more than one-third of global GDP growth and, in terms of purchasing power, their economies have grown from one-sixth of the global economy to almost a quarter.
Goldman Sachs predicts that the size of the BRICS economies as a whole will exceed the size of the US economy by 2018. By 2020, the BRICS countries are expected to account for approximately 49.0% of global GDP growth and these countries will account for one-third of the world economy based on purchasing power.
The positive global economic outlook is a confirmation of strong global industrial demand, which bodes well for the steel sector. Full global growth in steel production will continue to significantly impact niobium demand.
2. Increase in the amount of niobium used for steel production.
As steel end users' demands for higher quality products increase, steel mills must increase their use of niobium to produce steel that meets higher standards and specifications. In 2000, 40 grams of ferroniobium were added to 1 ton of steel. In 2008 it was already 63 grams per ton. Given that niobium represents a very small percentage of steel in terms of cost, but adds significant value by improving its features, especially strength, durability, lightness and flexibility, the use of this metal is expected to continue to increase across all end-use segments.
Steady growth in demand for niobium is expected to continue in the short and long term, while emerging markets continue to grow and applications for higher quality steels are already developed.
With increasing steel production and an increasing percentage of its niobium content, global consumption of ferroniobium is estimated to have increased by ~11% from ~78,100 t in 2010 to ~86,000 t in 2011.
The largest consumers of niobium are China, North America and Europe. China is the world's fastest growing market for niobium, accounting for 25% of total consumption in 2010. This reflects the size of its steel industry and the rapid pace of production growth in recent years. China is the world's leading producer of stainless steel, with its share of global production rising from 1-2% in the 1990s to 36.7% in 2010. China is also the largest and fastest growing producer of alloy steels, including HSLA steels.

Production and consumption of niobium in the world, thousand tons*

year	2008	2009	2010	2011	2012
Total production	67.9	40.6	59.4	65.7	62.9
Total consumption	58.1	40.6	48.9	61.5	62.9
Market balance	9.8	--	9.4	-0.4	-0.4

*data from Tantalum-Niobium International Study Center

In the early 2000s, niobium prices remained relatively stable, ranging from US$12.00 to US$13.50 per kilogram. Significant economic growth in emerging markets, especially the BRIC economies, and increased use of niobium in steel production pushed metal prices to US$32.63 per kg in 2007 and a further rise to US$60.00 per kg in 2012. Only in 2008 and 2009 did prices for niobium decrease slightly due to the global economic crisis. However, this decrease was much smaller than that of substitute metals.
From a consumer perspective, a stable price for niobium is a desirable feature as it allows for better prediction and cost planning accordingly. Additionally, end users emphasize the importance of sourcing niobium from multiple suppliers to minimize supply chain disruption and avoid over-reliance on a single manufacturer.
A key replacement for niobium is ferrovanadium, whose market has largely recovered from the collapse experienced during the financial crisis. However, ferrovanadium's comparatively higher price and significantly higher volatility have contributed to its replacement by ferroniobium, which has a more predictable price history.
Given the high value added by using niobium in the steelmaking process (i.e. added strength, durability, corrosion resistance, thermal resistance, weight reduction) and the relatively small share of the total cost, demand from metal buyers is quite inelastic. As an example, niobium is considered to constitute In addition, niobium is an additive to high value alloys that are used in technical fields (jet engine components, medical equipment, heavy engineering) where commitment to technical requirements and superior performance is a necessity. As a result, the share of niobium use in steel production has increased. This trend is expected to continue in the future.
Given the lack of active sales on the open market and the resulting lack of competitive pricing, few research analysts make predictions about future niobium prices, and those who do make such predictions tend to be conservative. Despite these factors, niobium is expected to be in demand in the near future, and metal prices will remain high. Some analysts expect niobium prices to continue to rise over the next two to three years, based on consumer interactions and future needs.

The construction, automotive and oil and gas sectors are expected to continue to account for the largest percentage of niobium consumption. These sectors were negatively impacted by the 2008 financial crisis but have bounced back in subsequent years and are predicted to grow at a steady rate.

Application of niobium for metal alloying

Niobium alloyed steel has good corrosion resistance. Chromium also increases the corrosion resistance of steel, and it is much cheaper than niobium. This reader is right and wrong at the same time. I’m wrong because I forgot about one thing.

Chromium-nickel steel, like any other, always contains carbon. But carbon combines with chromium to form carbide, which makes the steel more brittle. Niobium has a greater affinity for carbon than chromium. Therefore, when niobium is added to steel, niobium carbide is necessarily formed. Steel alloyed with niobium acquires high anti-corrosion properties and does not lose its ductility. The desired effect is achieved when only 200 g of niobium metal is added to a ton of steel. And niobium imparts high wear resistance to chrome-manganese steel.

Many non-ferrous metals are also alloyed with niobium. Thus, aluminum, which easily dissolves in alkalis, does not react with them if only 0.05% niobium is added to it. And copper, known for its softness, and many of its alloys seem to be hardened by niobium. It increases the strength of metals such as titanium, molybdenum, zirconium, and at the same time increases their heat resistance and heat resistance.

Now the properties and capabilities of niobium are appreciated by aviation, mechanical engineering, radio engineering, the chemical industry, and nuclear energy. All of them became consumers of niobium.

The unique property - the absence of noticeable interaction of niobium with uranium at temperatures up to 1100°C and, in addition, good thermal conductivity, a small effective absorption cross section of thermal neutrons - made niobium a serious competitor to metals recognized in the nuclear industry - aluminum, beryllium and zirconium. In addition, the artificial (induced) radioactivity of niobium is low. Therefore, it can be used to make containers for storing radioactive waste or installations for their use.

The chemical industry consumes relatively little niobium, but this can only be explained by its scarcity. Equipment for the production of high-purity acids is sometimes made from niobium-containing alloys and, less commonly, from sheet niobium. Niobium's ability to influence the rate of certain chemical reactions is used, for example, in the synthesis of alcohol from butadiene.

Rocket and space technology also became consumers of element No. 41. It is no secret that some quantities of this element are already rotating in near-Earth orbits. Some parts of rockets and on-board equipment of artificial Earth satellites are made from niobium-containing alloys and pure niobium.

Uses of niobium in other industries

“Hot fittings” (i.e., heated parts) are made from niobium sheets and bars - anodes, grids, indirectly heated cathodes and other parts of electronic lamps, especially powerful generator lamps.

In addition to pure metal, tantalonium-bium alloys are used for the same purposes.

Niobium was used to make electrolytic capacitors and current rectifiers. Here, the ability of niobium to form a stable oxide film during anodic oxidation is used. The oxide film is stable in acidic electrolytes and passes current only in the direction from the electrolyte to the metal. Niobium capacitors with solid electrolyte are characterized by high capacity with small dimensions and high insulation resistance.

Niobium capacitor elements are made from thin foil or porous plates pressed from metal powders.

The corrosion resistance of niobium in acids and other media, combined with high thermal conductivity and ductility, make it a valuable structural material for equipment in chemical and metallurgical industries. Niobium has a combination of properties that meet the requirements of nuclear energy for structural materials.

Up to 900°C, niobium weakly interacts with uranium and is suitable for the manufacture of protective shells for uranium fuel elements of power reactors. In this case, it is possible to use liquid metal coolants: sodium or an alloy of sodium and potassium, with which niobium does not interact up to 600°C. To increase the survivability of uranium fuel elements, uranium is doped with niobium (~ 7% niobium). The niobium additive stabilizes the protective oxide film on uranium, which increases its resistance to water vapor.

Niobium is a component of various heat-resistant alloys for jet engine gas turbines. Alloying molybdenum, titanium, zirconium, aluminum and copper with niobium dramatically improves the properties of these metals, as well as their alloys. There are heat-resistant alloys based on niobium as a structural material for parts of jet engines and rockets (manufacture of turbine blades, leading edges of wings, nose ends of aircraft and rockets, rocket skins). Niobium and alloys based on it can be used at operating temperatures of 1000 - 1200°C.

Niobium carbide is a component of some grades of tungsten carbide-based carbide used for cutting steels.

Niobium is widely used as an alloying additive in steels. The addition of niobium in an amount 6 to 10 times higher than the carbon content in steel eliminates intergranular corrosion of stainless steel and protects welds from destruction.

Niobium is also added to various heat-resistant steels (for example, for gas turbines), as well as to tool and magnetic steels.

Niobium is introduced into steel in an alloy with iron (ferroniobium), containing up to 60% Nb. In addition, ferrotantaloniobium is used with different ratios between tantalum and niobium in the ferroalloy.

In organic synthesis, some niobium compounds (fluoride complex salts, oxides) are used as catalysts.

The use and production of niobium are rapidly increasing, which is due to a combination of such properties as refractoriness, a small cross section for thermal neutron capture, the ability to form heat-resistant, superconducting and other alloys, corrosion resistance, getter properties, low electron work function, good workability under cold pressure and weldability. The main areas of application of niobium are: rocketry, aviation and space technology, radio engineering, electronics, chemical engineering, nuclear energy.

Applications of metallic niobium

Aircraft parts are made from pure niobium or its alloys; claddings for uranium and plutonium fuel elements; containers and pipes; for liquid metals; parts of electrolytic capacitors; “hot” fittings for electronic (for radar installations) and powerful generator lamps (anodes, cathodes, grids, etc.); corrosion-resistant equipment in the chemical industry.
Other non-ferrous metals, including uranium, are alloyed with niobium.
Niobium is used in cryotrons - superconducting elements of computers. Niobium is also known for its use in the accelerating structures of the Large Hadron Collider.

Intermetallic compounds and alloys of niobium

Nb 3 Sn stannide and alloys of niobium with titanium and zirconium are used for the manufacture of superconducting solenoids.
Niobium and alloys with tantalum in many cases replace tantalum, which gives a great economic effect (niobium is cheaper and almost twice as light as tantalum).
Ferroniobium is introduced into stainless chromium-nickel steels to prevent their intergranular corrosion and destruction and into other types of steel to improve their properties.
Niobium is used in the minting of collectible coins. Thus, the Bank of Latvia claims that niobium is used along with silver in 1 lat collection coins.

Application of niobium compounds

Nb 2 O 5 catalyst in the chemical industry;
in the production of refractories, cermets, specials. glass, nitride, carbide, niobates.
Niobium carbide (mp 3480 °C) alloyed with zirconium carbide and uranium-235 carbide is the most important structural material for fuel rods of solid-phase nuclear jet engines.
Niobium nitride NbN is used to produce thin and ultra-thin superconducting films with a critical temperature of 5 to 10 K with a narrow transition of the order of 0.1 K

Niobium in medicine

The high corrosion resistance of niobium has made it possible to use it in medicine. Niobium threads do not cause irritation to living tissue and adhere well to it. Reconstructive surgery has successfully used such threads to stitch together torn tendons, blood vessels and even nerves.

Application in jewelry

Niobium not only has a set of properties necessary for technology, but also looks quite beautiful. Jewelers tried to use this white shiny metal to make watch cases. Alloys of niobium with tungsten or rhenium sometimes replace noble metals: gold, platinum, iridium. The latter is especially important, since the niobium-rhenium alloy not only looks similar to the metallic iridium, but is almost as wear-resistant. This allowed some countries to do without expensive iridium in the production of soldering tips for fountain pen nibs.

Niobium as a first generation superconducting material

The amazing phenomenon of superconductivity, when when the temperature of a conductor decreases, an abrupt disappearance of electrical resistance occurs in it, was first observed by the Dutch physicist G. Kamerlingh-Onnes in 1911. The first superconductor turned out to be mercury, but not it, but niobium and some intermetallic compounds of niobium were destined to become the first technically important superconducting materials.

Two characteristics of superconductors are practically important: the value of the critical temperature at which the transition to the state of superconductivity occurs, and the critical magnetic field (Kamerlingh Onnes also observed the loss of superconductivity by a superconductor when exposed to a sufficiently strong magnetic field). In 1975, the intermetallic compound of niobium and germanium with the composition Nb 3 Ge became the record holder for the highest critical temperature. Its critical temperature is 23.2°K; This is higher than the boiling point of hydrogen. (Most known superconductors become superconductors only at the temperature of liquid helium).

The ability to transition to a state of superconductivity is also characteristic of niobium stannide Nb 3 Sn, alloys of niobium with aluminum and germanium or with titanium and zirconium. All these alloys and compounds are already used to make superconducting solenoids, as well as some other important technical devices.

One of the actively used superconductors (superconducting transition temperature 9.25 K). Niobium compounds have a superconducting transition temperature of up to 23.2 K (Nb 3 Ge).
The most commonly used industrial superconductors are NbTi and Nb 3 Sn.
Niobium is also used in magnetic alloys.
Used as an alloying additive.
Niobium nitride is used to produce superconducting bolometers.

The exceptional resistance of niobium and its alloys with tantalum in superheated cesium-133 vapor makes it one of the most preferred and cheapest structural materials for high-power thermionic generators.

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