Smart metal. This term appeared in the business world in the middle of the 20th century. Smart metals were used as materials for high technology used in electronics and robotics. One of such high-tech metals was tantalum. Today it is inextricably linked with concepts such as satellite communications, airborne systems, telecommunications equipment.
What is tantalum? Historical facts
Tantalum was first discovered in 1802 by the Swedish scientist A.G. Ekeberg composed of two minerals found in Sweden and Finland. The oxide of this element was very stable, and even a large amount of acid could not destroy its structure. The scientist had the impression that the metal cannot be saturated with acid. Ekeberg recalled the legend of King Tantalus, who was the son of Zeus and as a result of punishment could not satisfy his hunger and thirst. His suffering was called tantalum flour.
So the scientist, as he did not try, could not isolate pure metal from oxide, so he compared his work with tantalum flour. He gave the chemical element tantalum, and the mineral that contained this metal, called tantalite. Only in 1903, the German scientist chemist Bolton V. received in its pure form the ductile metal tantalum. Its industrial production began only in 1922. The first example of industrial production of tantalum was just a match head. The United States was the first to produce it, and in 1942 a plant was launched to produce this metal.
Physical properties of tantalum
What is tantalum? This is a silver-white metal. The strong oxide film on it gives a similar appearance to lead. The metal has high strength and hardness and at the same time ductility. Its plasticity is compared with gold.
In its pure form, it perfectly submits to machining. It is easy to stamp, rolls into a very thin layer up to 0.04 mm. From it get high-quality wire. Tantalum, what is it? This is a refractory metal with a melting point of approximately 3,000 degrees. Only tungsten and rhenium surpass it in this property. One of its specific qualities is its high thermal conductivity. Even the oxide film that forms on it does not reduce this property.
Chemical properties
Many organic and inorganic acids - perchloric, sulfuric, hydrochloric, nitric and other aggressive environments - do not cause tantalum corrosion. The metal oxidizes when heated from 200 to 300 degrees, and a gas-saturated layer is formed on it under the oxide film. The weak chemical properties of tantalum prevent it from dissolving even in aqua regia, which melts platinum and gold.
In practice, it has been proven that stainless steels are less resistant during operation, and their parts serve a much shorter period than tantalum products. Of all the existing acids, only hydrofluoric acid can dissolve this metal.
Alloys
The strong resistance of tantalum to the effects of acids allows it to be used for additives to various alloys that are used in the manufacture of metal structures. For the manufacture of rolled products - wire, strips, sheets, tubes - use an alloy of tantalum with hafnium. An alloy of titanium, tungsten and tantalum is used for the manufacture of cutting inserts for various purposes. Such alloys are characterized by:
- high strength
- increased hardness;
- not oxidized;
- have high abrasion resistance;
- are wear resistant;
- have significant viscosity;
- provide excellent strength to the cutting edge of the tool.
Tantalum-tungsten alloy, which includes 7% tungsten, is able to withstand temperatures up to 1900 degrees. It causes considerable interest among specialists. And from a tantalum alloy with 10% tungsten, nozzles for rocket engines are made. In space technology, materials are used that have good heat capacity or refractoriness; therefore, tantalum alloys are widely used for its manufacture.
The role of scrap
Tantalum scrap accounts for a significant share, up to 30% of supplies to the market, of the total. Most metal is released from scrap scrap capacitors. Therefore, its supplies are directly dependent on the activity in the electronic industry.
And this, in turn, is determined by global economic conditions. Other sources of scrap are spent carbides. The scrap alloy, the main element of which is nickel, also contains tantalum. In the future, consumer waste will be an important source of this metal.
Use of tantalum
The metal itself and its alloys are widely used in industry. It is used for the manufacture of:
- dry electrolytic capacitors;
- heaters for vacuum furnaces;
- cathodes of indirect heating;
- anticorrosion equipment;
- nuclear reactors;
- superconductors;
- ammunition with increased penetration;
- mass standards that have high accuracy;
- cutting tools of high durability.
The high corrosion resistance of the metal extends the life of tantalum capacitors in electronic systems up to 12 years.
The jewelry industry uses this metal to make watch cases and bracelets instead of platinum. Tantalum products are also used in the medical industry. It is not rejected by the human body, therefore it is produced from it:
- plates for the skulls and abdomen;
- paper clips that are used to connect vessels;
- eye prostheses ;
- thick threads that replace tendons;
- thin threads for stitching nerve fibers.
GOST metal
There are several methods for establishing GOST of tantalum and its oxide, for example, photometric and spectral.
The spectral method (GOST 18904.8) determines the content of calcium, tungsten, copper, cobalt, sodium, molybdenum impurities in tantalum and its oxide. The result of the analysis is the arithmetic mean obtained from 2 definitions of various weights.
The photometric method (GOST 18904.1) determines the content of the mass fraction of tungsten and molybdenum in tantalum and oxide. In this case, the result of the analysis is calculated as the arithmetic average of 3 determinations, which are performed from separate weights.
Tantalum deposits and mining
What is tantalum? This is a very rare metal. In its pure form, it is practically not observed. You can meet it in the composition of minerals and in the form of its own compounds. In minerals, it is always found together with niobium, which is very similar in properties to tantalum. Deposits with tantalum compounds and minerals are found in many countries of the world.
The largest is located in France. High reserves of this metal in China and Thailand. In the CIS countries, deposits are much smaller. About 420 tons of tantalum is annual production in the world. The main metal processing plants are located in Germany and the USA. Due to the rapid development of electronics, in which the use of tantalum is not the last, there is a shortage of this rare metal, which leads to the search for new deposits.
Tantalum prices
Most of the tantalum, up to 60%, is consumed by the electronics industry. Its use on heat-resistant alloys is about 20%. Prices for this rare metal can change rapidly. Demand for it is restored, then falls again. Analysts predict that in the coming years, supply and demand will fluctuate, this mainly depends on economic factors.
The estimated price of tantalum per 1 kg in rubles on the Russian market is:
- sheet - 65 660;
- in bars - 73 030;
- wire - 73,700.
Prospects
More and more are starting to use this smart metal in the medical industry for the needs of reconstructive surgery. It is used for the manufacture of implants. Muscle tissue is replaced with tantalum yarn, the wire is used to bond the bones, and the threads are used for suturing. In connection with the major re-equipment of world airlines, the use of tantalum for aircraft construction needs will continue to grow. Alloys in the aircraft industry are used for aircraft engines. In addition, tantalum continues to be actively used for the production of computer equipment: processors, printers.
Demand for this metal in the chemical industry does not decrease. It is widely used for the production of chlorine, hydrogen peroxide, many acids. Chemical engineering makes extensive use of it in the manufacture of equipment in contact with aggressive media. The most serious consumer of tantalum alloys remains the metallurgical industry. Demand for it is also growing in nuclear energy, where heat conduction is mainly used in combination with the ductility and hardness of tantalum.