The most refractory metal on the periodic table
Metals are the most common material (along with plastics and glass) that has been used by people since ancient times. Even then, man knew the characteristics of metals; he profitably used all their properties to create beautiful works of art, dishes, household items, and structures.
One of the main features when considering these substances is their hardness and refractoriness. It is these qualities that make it possible to determine the area of use of a particular metal. Therefore, we will consider all the physical properties and pay special attention to the issues of fusibility.
Physical properties of metals
The characteristics of metals by physical properties can be expressed in the form of four main points.
- Metallic luster - all have approximately the same silvery-white beautiful characteristic luster, except for copper and gold. They have a reddish and yellow tint, respectively. Calcium is silvery blue.
- Physical state - all solids under ordinary conditions, except mercury, which is in the form of a liquid.
- Electrical and thermal conductivity is characteristic of all metals, but is expressed to varying degrees.
- Malleability and ductility are also parameters common to all metals, which can vary depending on the specific representative.
- Melting and boiling points determine which metal is refractory and which is fusible. This parameter is different for all elements.
All physical properties are explained by the special structure of the metal crystal lattice. Its spatial arrangement, shape and strength.
Low-melting and refractory metals
This parameter is very important when it comes to the areas of application of the substances in question. Refractory metals and alloys are the basis of machine and shipbuilding, smelting and casting of many important products, and obtaining high-quality working tools. Therefore, knowledge of melting and boiling points plays a fundamental role.
Characterizing metals by strength, we can divide them into hard and brittle. If we talk about refractoriness, then there are two main groups:
- Low-melting materials are those that are capable of changing their state of aggregation at temperatures below 1000 o C. Examples include: tin, lead, mercury, sodium, cesium, manganese, zinc, aluminum and others.
- Refractory are those whose melting point is higher than the indicated value. There are not many of them, and even fewer are used in practice.
A table of metals with a melting point above 1000 o C is presented below. This is where the most refractory representatives are located.
| Metal name | Melting point, o C | Boiling point, o C |
| Gold, Au | 1064.18 | 2856 |
| Beryllium, Be | 1287 | 2471 |
| Cobalt, Co |
Source: https://ostwest.su/instrumenty/samyj-tugoplavkij-metall-v-tablice-mendeleeva.php/
Refractory metals
Refractory metals, according to technical classification - metals that melt at temperatures above 1650-1700 ° C; in the number of T. m.
(table) includes titanium Ti, zirconium Zr, hafnium Hf (IV several periodic aggregates), vanadium V, niobium Nb, tantalum Ta (V several), chromium Cr, molybdenum Mo, tungsten W (VI several), rhenium Re (VII several ).
All these elements (not counting Cr) are classified as rare metals, and Re are classified as trace metals. (Platinum group metals and thorium are also characterized by a high melting point, but according to the technical classification they do not belong to metals.) Refractory metals
Name
Chem.
symbol
Atom-
ny
number
External electronic
shell
Melting temperature
nia
Titanium
Vanadium
Chromium
Zirconium
Niobium
Molybdenum
Hafnium
Tantalum
Tungsten
Rhenium
Ti
V
Cr
Zr
Nb
Mo
Gf
Ta
W
Re
22
23
24
40
41
42
72
73
74
75
3d2 4s2
3d3 4s2
3d5 4s1
4d2 5s1
4d4 5s1
4d5 5s1
5d2 6s2
5d3 6s2
5d4 6s2
5d5 6s2
1688
1900
1903
1852
2500
2620
2222
2996
3410
3180
T. metals have a similar electronic structure of atoms and are transition elements with d-shells that can be completed (see table). Not only external s-electrons, but also d-electrons participate in interatomic bonds of metal, which determines the enormous strength of interatomic bonds and, as a consequence, a high melting point, increased mechanical strength, hardness, and electrical resistance. T. m. have native chemical characteristics.
The variable valence of metals determines the diversity of their chemical compounds; they form metal-like refractory rigid compounds.
In nature, metals are not found in free form; in minerals they quite often replace each other isomorphically: Hf is isomorphically associated with Zr, Ta with Nb, W with Mo; The separation of these pairs is one of the very difficult problems in chemical development, which is solved in most cases by methods of extraction or sorption from solutions or rectification of chlorides.
Physical and chemical features. The crystal lattices of Tm of group IV and Re are hexagonal, the rest, and Ti above 882 °C, Zr above 862 °C and Hf above 1310 °C are body-centered cubic. Ti, V and Zr are fairly light metals, and the most refractory of all metals - Re and W - are second only to Os, lr and Pt in density. Pure annealed metals are ductile metals that can be worked by both hot and cold pressure, especially those of groups IV and V.
For the use of thermometals, it is fundamentally important that the favorable mechanical properties of them and alloys based on them are preserved up to high temperatures; this allows us to consider them, for example, as heat-resistant structural materials. But the mechanical characteristics of steel materials largely depend on their purity, heat treatment conditions, and the degree of deformation.
Thus, Cr and its alloys, in addition, with a low content of certain impurities become non-plastic, and Re, which has a large elastic modulus, is subject to strong hardening, due to which, in addition, at a small degree of deformation it must be annealed. The properties of metals are especially strongly affected by impurities of carbon (except Re), hydrogen (for metals of groups IV and V), nitrogen, and oxygen, the presence of which makes metals brittle.
The characteristic features of all T. m. are resistance to the action of air and many aggressive environments at room temperature and low heating, and high reactivity at high temperatures, at which they are heated in a vacuum or in the air of gases inert to them. T. m. are especially active when heated.
Groups IV and V, which are also affected by hydrogen, and at 400–900 °C it is absorbed to form brittle hydrides, and when heated in a vacuum at 700–1000 °C it is released again; This is used to turn compact metals into powders by hydrogenating (and embrittling) the metals, dehydrogenating and grinding.
T. m. Group VI and Re are chemically less active (their activity decreases from Cr to W), they do not interact with hydrogen, and Re does not interact with nitrogen; cooperation of Mo with nitrogen begins only above 1500 °C, and W - above 2000 °C. T. m. are capable of forming alloys with many metals.
Receipt. Approximately 80–85% of V, Nb, Mo (USA, 1973) and large quantities of second heavy metals, not counting Hf, Ta and Re, are acquired from ore concentrates or technical oxides using alumino- or silicothermic methods in the form of ferroalloys for introduction into steel for alloying purposes; Molybdenum concentrates are also pre-fired.
Pure metals are acquired from ore concentrates through complex mining in 3 stages: opening of the concentrate, purification and isolation of chemical compounds, refining and recovery of the metal. The basis for the production of compact Nb, Ta, Mo, and W and their alloys is powder metallurgy, which is partially used in the production of other metals. In the metallurgy of all metals, arc, electron beam, and plasma melting are increasingly used.
T. metals and alloys of very high purity are created in the form of single crystals by crucibleless electron beam or plasma zone melting. Semi-finished products from T. m. - pages, foil, wire, pipes, etc. are produced by simple methods of metal forming with intermediate heat treatment.
Usage. The enormous importance of thermometers, compounds, and alloys is associated with their combinations of properties and the favorable properties characteristic of individual thermometers. The most significant area of application of most thermometers is.
- their use in the form of alloys as heat-resistant materials, primarily in aircraft construction, rocket and space technology, nuclear energy, and high-temperature technology. Details from alloys T. m.
Along with this, in most cases they are protected with heat-resistant coatings.
Metals and their alloys are also used as structural materials in mechanical engineering, marine shipbuilding, electronics, electrical engineering, chemical, nuclear industries, and other branches of technology. Oxides and many other chemical compounds of metals are widely used. For more details on the features, practical use, and methods of obtaining metals, see the articles on their individual alloys and elements.
Lit.: Refractory materials in mechanical engineering. Directory, M., 1967; Bases of metallurgy, vol. 4, M., 1967; Savitsky E. M., Burkhanov G. S., Metallurgy of refractory and rare metal alloys, 2nd ed., M., 1971; Krupin A.V., Soloviev V.Ya.
, Plastic deformation of refractory metals, M., 1971; 3elikman A. N., Meerson G. A., Metallurgy of rare metals, M., 1973; Savitsky E. M., Klyachko V. S., Metals of the Space Era, M., 1972; technology and Chemistry of rare and trace elements, vol. 1-2, M.
, 1965-69; Engineering and Mining Journal, 1974, v. 175, March.
O. P. Kolchin.
Related articles:
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Source: http://australianembassy.ru/tugoplavkie-metally/
Which metal is the most fusible and refractory?
Refractory metals have been known since the end of the 19th century. There was no use for them then. The only industry where they were used was electrical engineering, and then in very limited quantities. But everything changed dramatically with the development of supersonic aviation and rocket technology in the 50s of the last century. The production required new materials that could withstand significant loads at temperatures above 1000 ºC.
List and characteristics of refractory metals
Refractoriness is characterized by an increased value of the transition temperature from the solid state to the liquid phase. Metals that melt at 1875 ºC and above are classified as refractory metals. In order of increasing melting temperature, these include the following types:
Modern production in terms of the number of deposits and the level of production is satisfied only by tungsten, molybdenum, vanadium and chromium. Ruthenium, iridium, rhodium and osmium are quite rare in natural conditions. Their annual production does not exceed 1.6 tons.
Heat-resistant metals have the following main disadvantages:
- Increased cold brittleness. It is especially pronounced in tungsten, molybdenum and chromium. The transition temperature of a metal from a ductile to a brittle state is slightly above 100 ºC, which creates inconvenience when processing them under pressure.
- Instability to oxidation. Because of this, at temperatures above 1000 ºC, refractory metals are used only with preliminary application of galvanic coatings to their surface. Chromium is the most resistant to oxidation processes, but as a refractory metal it has the lowest melting point.
The most promising refractory metals include niobium and molybdenum. This is due to their prevalence in nature, and, consequently, low cost in comparison with other elements of this group.
In addition, niobium has established itself as a metal with a relatively low density, increased manufacturability and fairly high refractoriness. Molybdenum is valuable, first of all, for its specific strength and heat resistance.
The most refractory metal found in nature is tungsten. Its mechanical characteristics do not decrease at ambient temperatures above 1800 ºC. But the disadvantages listed above plus increased density limit its scope of use in production. As a pure metal, it is used less and less. But the value of tungsten as an alloying component increases.
Physical and mechanical properties
Metals with a high melting point (refractory) are transition elements. According to the periodic table, there are 2 types of them:
- Subgroup 5A – tantalum, vanadium and niobium.
- Subgroup 6A – tungsten, chromium and molybdenum.
Vanadium has the lowest density - 6100 kgm3, tungsten has the highest density - 19300 kgm3. The specific gravity of the remaining metals is within these values. These metals are characterized by a low coefficient of linear expansion, reduced elasticity and thermal conductivity.
These metals do not conduct electricity well, but have the quality of superconductivity. The temperature of the superconducting regime is 0.05-9 K based on the type of metal.
Absolutely all refractory metals are characterized by increased ductility under room conditions. Tungsten and molybdenum also stand out from other metals due to their higher heat resistance.
Corrosion resistance
Heat-resistant metals are characterized by high resistance to most types of aggressive environments. The corrosion resistance of elements of subgroups 5A increases from vanadium to tantalum. As an example, at 25 ºC vanadium dissolves in aqua regia, while niobium is completely inert towards this acid.
Tantalum, vanadium and niobium are resistant to molten alkali metals. Provided there is no oxygen in their composition, which significantly increases the intensity of the chemical reaction.
Molybdenum, chromium and tungsten have greater resistance to corrosion. Thus, nitric acid, which actively dissolves vanadium, has a much less effect on molybdenum. At a temperature of 20 ºC this reaction completely stops.
All refractory metals readily enter into chemical bonds with gases. The absorption of hydrogen from the environment by niobium occurs at 250 ºC. Tantalum at 500 ºC. The only way to stop these processes is to carry out vacuum annealing at 1000 ºC. It is worth noting that tungsten, chromium and molybdenum are much less prone to interact with gases.
Source: https://master-kleit.ru/origami/kakoj-metall-samyj-legkoplavkij-i-tugoplavkij/
The most refractory metal. Characteristics of metals
Metals are the most common material (along with plastics and glass) that has been used by people since ancient times. Even then, man knew the characteristics of metals; he profitably used all their properties to create beautiful works of art, dishes, household items, and structures.
One of the main features when considering these substances is their hardness and refractoriness. It is these qualities that make it possible to determine the area of use of a particular metal. Therefore, we will consider all the physical properties and pay special attention to the issues of fusibility.
Refractory metals - characteristics, properties and applications
Refractory metals have been known since the end of the 19th century. There was no use for them then. The only industry where they were used was electrical engineering, and then in very limited quantities. But everything changed dramatically with the development of supersonic aviation and rocket technology in the 50s of the last century. The production required new materials that could withstand significant loads at temperatures above 1000 ºC.
Cold brittleness
The spread of the use of heat-resistant metals in production is hampered by their increased tendency to cold brittleness. This means that when the temperature drops below a certain level, the brittleness of the metal sharply increases. For vanadium this temperature is -195 ºC, for niobium -120 ºC, and tungsten +330 ºC.
The presence of cold brittleness in heat-resistant metals is due to the content of impurities in their composition. Molybdenum of special purity (99.995%) retains increased plastic properties up to the temperature of liquid nitrogen. But the introduction of only 0.1% oxygen shifts the cold brittleness point to -20 C.
Areas of use
Until the mid-40s, refractory metals were used only as alloying elements to improve the mechanical characteristics of non-ferrous steel alloys based on copper and nickel in the electrical industry. Compounds of molybdenum and tungsten were also used in the production of hard alloys.
The technical revolution associated with the active development of aviation, the nuclear industry and rocket science has found new ways to use refractory metals. Here is a partial list of new applications:
- Production of heat shields for the head unit and rocket frames.
- Structural material for supersonic aircraft.
- Niobium serves as a material for the honeycomb panel of spacecraft. And in rocket science it is used as heat exchangers.
- Thermojet and rocket engine components: nozzles, tail skirts, turbine blades, nozzle flaps.
- Vanadium is the basis for the manufacture of thin-walled tubes of fusion reactor fuel elements in the nuclear industry.
- Tungsten is used as the filament of electric lamps.
- Molybdenum is increasingly used in the production of electrodes used for melting glass. In addition, molybdenum is a metal used to produce injection molds.
- Production of tools for hot processing of parts.
Source: https://prompriem.ru/metally/tugoplavkie-metally.html
Amazing properties of the most refractory metal on Earth
Chemistry
328
1 month ago
Camila
Tungsten is one of the strongest and most abrasion-resistant metals on our planet. Its compounds are used to make shells for shells, armor, parts for aircraft, and radioactive substances are stored in tungsten containers, because they absorb harmful gamma radiation. How was the substance discovered, and what properties make it indispensable for humans? We tell you all the most interesting things.
A little history
The metal was discovered by the famous Swedish chemist K. W. Scheele in 1781.
The crust of our planet contains 0.00013% tungsten, which is very little. In nature, it is found in various rocks and oxidized compounds.
Easily turns into thread
Tungsten melts at a huge temperature, it is no less than +3,422 °C. With a density of about 19.3 g/cu. cm, it lends itself perfectly to forging, stretching into the thinnest thread at a temperature of +1,600 °C. The density is close to gold, for which it is 19.32 g/cubic meter. cm. In the recent past, there were cases when fraudsters inserted tungsten rods into gold alloys, thereby preventing the determination of the true weight of the noble metal.
Externally, tungsten is similar to platinum. The sparkling gray metal is produced by separating WO3 (tungsten trioxide) from tungsten ores. Then a current is passed through the resulting metal powder and heated to +3,000 °C. This creates a pure alloy.
The largest reserves of tungsten are located in Kazakhstan, America, China, and Canada. Deposits have also been discovered in countries such as Russia, South Korea, Armenia, Bolivia, Uzbekistan, and Portugal.
Tungsten filament lamp
In addition to its high strength, tungsten is ductile, which is why it is often used in the production of incandescent filaments for light bulbs and picture tubes.
Ultra-high-speed gyroscope rotors, used in the construction of ballistic missiles and stabilizing their flight, are made from this most reliable metal.
In resistance furnaces, tungsten allows temperatures to reach +2,500 °C. These electric ovens are used for heating, drying and melting materials, so the maximum temperature plays an important role in their operation.
At a temperature of +13,610 °C, the strongest and most refractory metal turns into gas!
Armor-piercing bullet cores are made of tungsten.
The progenitor of life on Earth
The Germans called tungsten “wolf rahm”, which translates as “wolf foam”. The origin of this phrase is quite simple: tungsten interfered with the smelting of Sn (tin), turning it into useless foam. “It devours a lamb like a wolf,” this is what the Germans said about the interaction of tin and tungsten. However, if in our country and Germany the name of the metal is consonant, then in the UK and the USA, for example, it sounds like “tungsten” - “heavy stone” translated from Swedish.
With an atomic mass lower than that of lead, tungsten has a density 1.7 times greater.
There are bacteria and archaebacteria on Earth that use this metal in metabolic processes! This leads scientists to believe that 4 billion years ago, tungsten played a vital role in the origin of life on our planet.
Source: https://vashurok.ru/articles/2019-12-20-volfram-udivitelny
The most refractory metal in the world: properties, production, application - Website about
Metals are among the most common materials, along with glass and plastics. They have been used by people since ancient times.
In practice, people learned the properties of metals and used them profitably to make dishes, household items, various structures and works of art.
The main characteristics of these materials are their refractoriness and hardness. Actually, their application in a particular area depends on these qualities.
Refractoriness of metals
This parameter becomes important when the question arises about the practical use of metals. For such important sectors of the national economy as aircraft construction, shipbuilding, and mechanical engineering, the basis is refractory metals and their alloys.
In addition, they are used for the manufacture of high-strength working tools. Many important parts and products are produced by casting and smelting. Based on their strength, all metals are divided into brittle and hard, and based on their refractoriness they are divided into two groups.
Refractory and low-melting metals
- Refractory - their melting point exceeds the melting point of iron (1539 °C). These include platinum, zirconium, tungsten, tantalum. There are only a few types of such metals. In practice, even fewer are used.
Some are not used because they have high radioactivity, others are too fragile and do not have the necessary softness, others are susceptible to corrosion, and there are others that are not economically viable.
Which metal is the most refractory? This is exactly what will be discussed in this article.
- Low-melting metals are metals that, at a temperature less than or equal to the melting point of tin 231.9 °C, can change their state of aggregation. For example, sodium, manganese, tin, lead. Metals are used in radio and electrical engineering.
They are often used for anti-corrosion coatings and as conductors.
Tungsten is the most refractory metal
It is a hard and heavy material with a metallic luster, light gray in color, and has high refractoriness. It is difficult to machine. At room temperature it is a brittle metal and breaks easily.
This is caused by contamination with oxygen and carbon impurities. Technically pure tungsten becomes plastic at temperatures above 400 degrees Celsius. It exhibits chemical inertness and reacts poorly with other elements.
In nature, tungsten occurs in the form of complex minerals, such as:
- scheelitis;
- wolframite;
- ferberite;
- hübnerite.
Tungsten is obtained from ore using complex chemical processing in powder form. Using pressing and sintering methods, simple shaped parts and bars are produced. Tungsten is a very temperature-resistant element. Therefore, they could not soften the metal for a hundred years.
There were no furnaces that could heat up to several thousand degrees. Scientists have proven that tungsten is the most refractory metal.
Although there is an opinion that seaborgium, according to theoretical data, has greater refractoriness, this cannot be stated firmly, since it is a radioactive element and has a short lifespan.
Historical information
The famous Swedish chemist Karl Scheele, who had the profession of a pharmacist, discovered manganese, barium, chlorine and oxygen in a small laboratory, conducting numerous experiments.
And shortly before his death in 1781, he discovered that the mineral tungsten was a salt of an acid then unknown. After two years of work, his students, the two d'Eluyard brothers (Spanish chemists), isolated a new chemical element from the mineral and named it tungsten.
Only a century later, tungsten - the most refractory metal - made a real revolution in industry.
Cutting properties of tungsten
In 1864, English scientist Robert Muschet used tungsten as an alloying additive to steel, which could withstand red heat and further increase hardness. The cutters, which were made from the resulting steel, increased the metal cutting speed by 1.5 times, and it became 7.5 meters per minute.
Working in this direction, scientists received new technologies, increasing the speed of metal processing using tungsten.
In 1907, a new compound of tungsten with cobalt and chromium appeared, which became the founder of hard alloys capable of increasing cutting speed.
Currently, it has increased to 2000 meters per minute, and all this is thanks to tungsten - the most refractory metal.
Applications of tungsten
This metal has a relatively high price and is difficult to process mechanically, so it is used where it is impossible to replace it with other materials of similar properties.
Tungsten perfectly withstands high temperatures, has significant strength, is endowed with hardness, elasticity and refractoriness, therefore it is widely used in many areas of industry:
- Metallurgical. It is the main consumer of tungsten, which is used to produce high-quality alloy steels.
- Electrotechnical. The melting point of the most refractory metal is almost 3400 °C. The refractoriness of the metal allows it to be used for the production of incandescent filaments, hooks in lighting and electronic lamps, electrodes, X-ray tubes, and electrical contacts.
- Mechanical engineering. Due to the increased strength of steels containing tungsten, solid forged rotors, gears, crankshafts, and connecting rods are manufactured.
- Aviation. What is the most refractory metal used to produce hard and heat-resistant alloys, from which parts of aircraft engines, electric vacuum devices, and incandescent filaments are made? The answer is simple - it is tungsten.
- Space. Steel containing tungsten is used to produce jet nozzles and individual elements for jet engines.
- Military. The high density of the metal makes it possible to produce armor-piercing shells, bullets, armor protection for torpedoes, shells and tanks, and grenades.
- Chemical. Resistant tungsten wire against acids and alkalis is used for filter meshes. Tungsten is used to change the rate of chemical reactions.
- Textile. Tungstic acid is used as a dye for fabrics, and sodium tungstate is used to make leather, silk, water-resistant and fire-resistant fabrics.
The above list of uses of tungsten in various areas of industry indicates the high value of this metal.
Preparation of alloys with tungsten
Tungsten, the world's most refractory metal, is often used to make alloys with other elements to improve the properties of materials. Alloys that contain tungsten are usually produced using powder metallurgy technology, since the conventional method turns all metals into volatile liquids or gases at its melting point.
The fusion process takes place in a vacuum or argon atmosphere to avoid oxidation. A mixture of metal powders is pressed, sintered and melted. In some cases, only tungsten powder is pressed and sintered, and then the porous workpiece is saturated with a melt of another metal.
Alloys of tungsten with silver and copper are obtained in this way. Even small additions of the most refractory metal increase heat resistance, hardness and oxidation resistance in alloys with molybdenum, tantalum, chromium and niobium. The proportions in this case can be absolutely anything depending on the needs of the industry.
More complex alloys, depending on the ratio of components with iron, cobalt and nickel, have the following properties:
- do not fade in air;
- have good chemical resistance;
- have excellent mechanical properties: hardness and wear resistance.
Tungsten forms rather complex compounds with beryllium, titanium and aluminum. They are distinguished by their resistance to oxidation at high temperatures, as well as heat resistance.
Properties of alloys
In practice, tungsten is often combined with a group of other metals.
Tungsten compounds with chromium, cobalt and nickel, which have increased resistance to acids, are used for the manufacture of surgical instruments.
And special heat-resistant alloys, in addition to tungsten - the most refractory metal, contain chromium, nickel, aluminum, and nickel. Tungsten, cobalt and iron are among the best grades of magnetic steel.
Tungsten-containing steels are resistant to abrasion, do not crack, and always remain hard. Cutting tools not only increase the speed of metal processing, but also have a long service life.
The most fusible and refractory metals
Low-melting metals include all metals whose melting point is lower than that of tin (231.9 °C). Elements of this group are used as anti-corrosion coatings, in electrical and radio engineering, and are part of anti-friction alloys.
Mercury, whose melting point is -38.89 °C, is a liquid at room temperature and is widely used in scientific instruments, mercury lamps, rectifiers, switches, and chlorine production. Mercury has the lowest melting point compared to other metals included in the fusible group.
Refractory metals include all metals whose melting point is higher than that of iron (1539 °C). They are most often used as additives in the manufacture of alloy steels, and they can also serve as the basis for some special alloys.
Tungsten, which has a maximum melting point of 3420 °C, is used in its pure form mainly for filaments in electric lamps.
Quite often in crossword puzzles questions are asked: which metal is the most fusible or the most refractory? Now, without hesitation, you can answer: the most fusible is mercury, and the most refractory is tungsten.
Briefly about hardware
This metal is called the main structural material. Iron parts are found both on a spaceship or submarine, and at home in the kitchen in the form of cutlery and various decorations.
This metal has a silver-gray color, has softness, ductility and magnetic properties. Iron is a very active element; an oxide film forms in air, which prevents the continuation of the reaction.
Rust appears in a humid environment.
Melting point of iron
Iron has ductility, is easily forged and is difficult to cast. This durable metal is easily processed mechanically and is used for the manufacture of magnetic drives.
Good malleability allows it to be used for decorative decorations. Is iron the most refractory metal? It should be noted that its melting point is 1539 °C.
And by definition, refractory metals include metals whose melting point is higher than that of iron.
We can definitely say that iron is not the most refractory metal, and does not even belong to this group of elements. It belongs to medium-melting materials. What is the most refractory metal? Such a question will not take you by surprise now. You can safely answer – it’s tungsten.
Instead of a conclusion
Approximately thirty thousand tons per year of tungsten are produced worldwide. This metal is certainly included in the best grades of steel for making tools. Up to 95% of all tungsten produced is consumed for the needs of metallurgy.
To reduce the cost of the process, they mainly use a cheaper alloy consisting of 80% tungsten and 20% iron. Using the properties of tungsten, its alloy with copper and nickel is used to produce containers used for storing radioactive substances.
In radiotherapy, the same alloy is used to make screens, providing reliable protection.
Source: https://nzmetallspb.ru/benzoinstrument/samyj-tugoplavkij-metall-v-mire-svojstva-poluchenie-primenenie.html
Which metal is the most refractory?
The strongest stable oxidizing agent is a complex of krypton difluoride and antimony pentafluoride. Due to its strong oxidizing effect (oxidizes all elements to higher oxidation states, including oxygen and nitrogen in the air), it is very difficult for it to measure the electrode potential. The only solvent that reacts with it slowly enough is anhydrous hydrogen fluoride.
The densest substance is osmium. Its density is 22.5 g/cm3.
The lightest metal is lithium. Its density is 0.543 g/cm3.
The most expensive metal is Californian. Its current cost is $6,500,000 per gram.
The most abundant element in the earth's crust is oxygen. Its content is 49% of the mass of the earth's crust.
The rarest element in the earth's crust is astatine. Its content in the entire earth's crust, according to experts, is only 0.16 grams.
The most flammable substance is apparently fine zirconium powder. To prevent it from burning, it is necessary to place it in an inert gas atmosphere on a plate made of a material that does not contain non-metals.
The substance with the lowest boiling point is helium. Its boiling point is -269 degrees Celsius. Helium is the only substance that does not have a melting point at normal pressure. Even at absolute zero it remains liquid. Liquid helium is widely used in cryogenic technology.
The most refractory metal is tungsten. Its melting point is +3420 degrees Celsius. It is used to make filaments for light bulbs.
The most refractory material is an alloy of hafnium and tantalum carbides (1:1). It has a melting point of +4215 C.
The most fusible metal is mercury. Its melting point is -38.87 degrees Celsius. It is also the heaviest liquid , its density is 13.54 g/cm3.
Antimony trichloride has the highest solubility in water among solids Its solubility at +25 C is 9880 grams per liter.
The lightest gas is hydrogen. The mass of 1 liter is only 0.08988 grams.
The heaviest gas at room temperature is tungsten hexafluoride (bp +17 C). Its mass is 12.9 g/l, i.e. Some types of foam may float in it.
The most acid-resistant metal is iridium. Until now, not a single acid or mixture thereof is known in which it would dissolve.
the widest range of concentration explosive limits . All mixtures of carbon disulfide vapor with air containing from 1 to 50 volume percent carbon disulfide can explode.
The strongest stable acid is a solution of antimony pentafluoride in hydrogen fluoride. Depending on the concentration of antimony pentafluoride, this acid can have a Hammett index of up to -40.
The most unusual anion in salt is the electron. It is part of the 18-crown-6 sodium complex electride.
Records for organic matter
The most bitter substance is denatonium saccharinate. It was obtained by accident during research on denatonium benzoate. The combination of the latter with the sodium salt of saccharin produced a substance 5 times more bitter than the previous record holder (denatonia benzoate). Currently, both of these substances are used to denature alcohol and other non-food products.
The most powerful poison is botulinum toxin type A. Its lethal dose for mice (LD50, intraperitoneal) is 0.000026 μg/kg body weight. It is a protein with a molecular weight of 150,000 produced by the bacterium Clostridium botulinum.
The most non-toxic organic substance is methane. When its concentration increases, intoxication occurs due to a lack of oxygen, and not as a result of poisoning.
The strongest adsorbent was obtained in 1974 from a starch derivative, acrylamide and acrylic acid. This substance is capable of holding water, the mass of which is 1300 times greater than its own.
The most smelly compounds are ethyl selenol and butyl mercaptan. The concentration that a person can detect by smell is so small that there are still no methods to accurately determine it. It is estimated to be 2 nanograms per cubic meter of air.
The most powerful hallucinogenic substance is l-lysergic acid diethylamide. A dose of just 100 micrograms causes hallucinations that last for about a day.
The sweetest substance is N-(N-cyclononylamino(4-cyanophenylimino)methyl)-2-aminoacetic acid. This substance is 200,000 times sweeter than a 2% sucrose solution, but due to its toxicity, it apparently will not find use as a sweetener. Of the industrial substances, the sweetest is talin, which is 3,500 - 6,000 times sweeter than sucrose.
The slowest enzyme is nitrogenase, which catalyzes the absorption of atmospheric nitrogen by nodule bacteria. The complete cycle of converting one nitrogen molecule into 2 ammonium ions takes one and a half seconds.
The longest chemical name published in the literature contained 1,578 letters and symbols and described a synthetic analogue of a chain of nucleotides.
The most powerful narcotic analgesic is apparently a substance synthesized in Canada in the 80s. Its effective analgesic dose in mice (subcutaneous administration) is only 3.7 nanograms per kilogram of body weight, making it 500 times more potent than etorphine.
The organic compound with the highest nitrogen content is bis(diazotetrazolyl)hydrazine. It contains 87.5% nitrogen. This explosive is extremely sensitive to shock, friction and heat.
The substance with the largest molecular weight is snail hemocyanin (carries oxygen). Its molecular weight is 918,000,000 daltons, which is greater than the molecular weight of even DNA.
The most refractory metal
The most refractory metal, tungsten (wolframium), was obtained in 1783. Spanish chemists the d'Eluyar brothers isolated it from the mineral wolframite and reduced it with carbon. Currently, the raw materials for the production of tungsten are wolframite and scheelite concentrates - WO3.
Tungsten powder is produced in electric furnaces at a temperature of 700–850 °C. The metal itself is produced from powder by pressing in steel molds under pressure and further heat treatment of the workpieces.
The final point is that heating to approximately 3000 °C occurs by passing an electric current.
Tungsten did not find industrial application for a long time. Only in the 19th century did they begin to study the influence of tungsten on the properties of steel of a different nature. At the beginning of the twentieth century, tungsten began to be used in light bulbs: a filament made from it heats up to 2200 °C. In this capacity, tungsten is indispensable in our time.
Tungsten steels are also used in the defense industry - for the production of tank armor, torpedoes and shells, the thinnest parts of aircraft, etc. The tool, made of tungsten steel, can withstand the most intense metalworking processes.
Tungsten differs from all other metal brethren in its special refractoriness, heaviness and hardness. Pure tungsten melts at 3380 °C, but boils only at 5900 °C, which coincides with the temperature on the surface of the Sun.
From one kilogram of tungsten you can make a wire 3.5 km long. This length is enough to produce filaments for 23,000 60-watt light bulbs.
By the way, the most fusible metal is mercury.
Elena Ozerova, Samogo.Net
Which metal is the most refractory?
Source: https://superfb.site/other/obrazovanie/srednee-obrazovanie/kakoj-metall-samyj-tugoplavkij.html
10 interesting facts about metals and their amazing properties
Metals are a group of chemical elements in the form of simple substances. They all have their own properties, according to which they can be divided into different groups.
The word “metal” itself came into Russian from Germany. At first it meant the same thing as “mineral, ore.” They began to separate concepts only after Lomonosov’s works.
The word has entered the language remarkably well, now everyone knows it. The most famous metals are probably gold, silver, mercury, copper and iron. But knowledge even about them is very incomplete. Nature always finds something to surprise us with.
In this article we will look at 10 interesting facts about metals.
10. Titanium is used as an implant
Implantation is a way to restore lost teeth.
Now this method is very common due to its speed and accessibility. It consists of the following: a rod is implanted into the jaw, which becomes a support for the new tooth. This very rod is made of titanium.
As a metal, it has high strength, and its elasticity is similar to human bone, so implantation is easier. Titanium is the very basis of a dental implant, which reduces the risk of bone destruction .
9. Silver has bactericidal properties
Silver was known to people even before our era. For some time it was even valued higher than gold. However, people are still learning about its various properties.
For example, the direct effect of ionic silver on bacteria is still debated. It has been proven that when bacteria and ions come into contact, the former die as a result of exposure.
Many theories have already been put forward, but the exact reasons for the death of microorganisms under the influence of silver are still unknown.
The ions of this metal cope well with the pathogens of typhoid, protea, diphtheria and others . Where silver does not kill bacteria, it may slow the germination of new spores and the spread of microorganisms.
8. Tantalum is widely used in prosthetics
Tantalum is an unusual metal that is quite rarely found in its pure form. For this reason it became very expensive.
He is difficult to obtain, so he was named after the hero of Greek myths. There Tantalus constantly tried to get at least a little food and water, but he still failed.
A chemist trying to obtain this metal in its pure form compared his work to tantalum flour. Despite this, tantalum has now found application in many areas.
It is very widespread in medicine because the human body does not reject it . It is used to produce plates for skulls, paper clips for connecting blood vessels, threads for replacing tendons and stitching together fibers. Sometimes used to make eye prostheses.
7. Aluminum is part of the earth's crust
Immediately after its discovery, aluminum was highly valued due to its similarity to silver. And extracting it in its pure form was not easy.
Scientists have already proven that this metal is widespread everywhere. Almost 8% of the earth's crust consists of it .
If we compare metals by the amount of their content in the earth's crust, it is second only to oxygen and silicon. But here’s an interesting fact: despite its prevalence, aluminum cannot be found in nature in its free form.
6. Mercury evaporates into the air
When people first discovered mercury, it was given the name "living silver." This is a very accurate definition of what mercury looks like.
The rare metal is a liquid, but it is also very heavy. The most common item where you can see mercury is an old thermometer. All parents forbid their children to touch it. And all because of the properties of mercury, which can evaporate in the air .
The vapors generated during evaporation are very toxic and can harm the human body. They penetrate inside, disrupt the composition and structure of proteins, which is why some processes begin to flow in the opposite direction, which entails poisoning and death.
But only large amounts of this metal cause death, more than in a regular thermometer. However, measures to eliminate the problem must be taken immediately in any case.
5. Tin is the most fusible metal
One metal that has already revealed almost all its secrets to people is tin. It has been known to mankind for a long time.
Before the discovery of the properties of iron, almost everything was made from an alloy of tin and copper: from weapons to jewelry. And this is understandable.
Tin is one of the most fusible metals . Its temperature is 232 - 240 degrees Celsius. Thus, only one requirement must be met - for molds it should not melt at temperatures up to 250 degrees. That's all, this metal has no more restrictions for melting, casting, soldering and other uses.
4. Iridium is the densest metal
Iridium is an interesting metal. It is found in the earth's crust even less frequently than gold and platinum. There is an assumption that its quantity is much larger, but it is located closer to the Earth’s core, out of reach.
Relative to the earth's crust, iridium is often found in meteorites. It is the densest and most refractory metal .
Its melting point is 2466 degrees Celsius. In terms of density, it is comparable only to osmium. They are almost equal, and the difference in numbers can be attributed to an error.
3. The Valcambi company produces ingots from expensive metals in the form of chocolate bars
Valcambi is an organization in Switzerland that has taken a very creative approach to the concept of ingots.
When they say the phrase “gold bars,” people always imagine beautiful shiny bricks stacked on top of each other in a pyramid. But the company decided to destroy this idea.
They make gold, silver, platinum and palladium bars in the form of chocolate bars . This was a wonderful gift idea.
Such an ingot can be broken into several small pieces (about 1 gram) and given as a gift to loved ones. Another use case is to pay for purchases in stores that accept this type of payment, of course.
2. Olympic medals are not gold at all.
Olympic gold medals are silver . In fact, the International Olympic Committee has declared that gold sports awards must be plated with just 6 grams of gold.
The rest of the medals may be silver. So, for example, if you study a medal from the London 2012 Olympic Games, the research results will be quite surprising. gold in a gold medal is only 1%, although all conditions are met.
1. More than 50% of the world's gold is found in Africa
For as long as humanity has existed, people have been drawn to gold. Finding a vein meant untold riches. For his sake they lied, stole, killed. But using all the methods possible to us, about 161 thousand tons of it have been found throughout history.
Most of this expensive metal was discovered in South Africa . But in reality this is not as much as it might seem at the very beginning. It is easier to present this fact differently.
If you melt all the gold found in the world into one large cube, its side will be only 20 meters. Half of this cube was found in Africa. Approximately every hour people take out a cube of iron of the same size from the ground. And all the gold in the world is worth about 9 trillion dollars.
Source: https://top10a.ru/interesnye-fakty-o-metallax.html
The most refractory metal on earth
Curious people are probably interested in the question, which metal is the most refractory? Before answering it, it is worth understanding the concept of refractoriness itself. All metals known to science have different melting points due to varying degrees of stability of bonds between atoms in the crystal lattice. The weaker the bond, the lower the temperature required to break it.
The world's most refractory metals are used in their pure form or in alloys to produce parts that operate under extreme thermal conditions. They can effectively withstand high temperatures and significantly extend the operating life of the units. But the resistance of metals of this group to thermal effects forces metallurgists to resort to non-standard methods of their production.
Which metal is the most refractory?
The most refractory metal on Earth was discovered in 1781 by the Swedish scientist Carl Wilhelm Scheele. The new material is called tungsten. Scheele was able to synthesize tungsten trioxide by dissolving the ore in nitric acid.
The pure metal was isolated two years later by Spanish chemists Fausto Fermin and Juan José de Eluar. The new element did not immediately gain recognition and was adopted by industrialists.
The fact is that the technology of that time did not allow processing such a refractory substance, so most contemporaries did not attach much importance to the scientific discovery.
Tungsten was appreciated much later. Today, its alloys are used in the production of heat-resistant parts for various industries. The filament in gas-discharge household lamps is also made of tungsten.
It is also used in the aerospace industry for the production of rocket nozzles, and is used as reusable electrodes in gas arc welding.
In addition to being refractory, tungsten also has a high density, which makes it suitable for making high-quality golf clubs.
Tungsten compounds with non-metals are also widely used in industry. So sulfide is used as a heat-resistant lubricant that can withstand temperatures up to 500 degrees Celsius, carbide is used to make cutters, abrasive discs and drills that can handle the hardest substances and withstand high heating temperatures. Let us finally consider the industrial production of tungsten. The most refractory metal has a melting point of 3422 degrees Celsius.
How is tungsten obtained?
Pure tungsten does not occur in nature. It is part of rocks in the form of trioxide, as well as wolframites of iron, manganese and calcium, less often copper or lead. According to scientists, the tungsten content in the earth's crust averages 1.3 grams per ton.
This is a rather rare element compared to other types of metals. tungsten in ore after mining usually does not exceed 2%.
Therefore, the extracted raw materials are sent to processing plants, where the mass fraction of metal is brought to 55-60% using magnetic or electrostatic separation.
The process of its production is divided into technological stages. In the first stage, pure trioxide is isolated from the mined ore. For this purpose, the thermal decomposition method is used. At temperatures from 500 to 800 degrees Celsius, all excess elements melt, and refractory tungsten in the form of oxide can be easily collected from the melt. The output is raw material with a hexavalent tungsten oxide content of 99%.
The resulting compound is thoroughly crushed and a reduction reaction is carried out in the presence of hydrogen at a temperature of 700 degrees Celsius. This allows you to isolate pure metal in powder form.
Next, it is pressed under high pressure and sintered in a hydrogen environment at temperatures of 1200-1300 degrees Celsius.
After this, the resulting mass is sent to an electric melting furnace, where, under the influence of current, it is heated to a temperature of over 3000 degrees. This is how tungsten turns into a molten state.
For final purification from impurities and obtaining a single-crystal structural lattice, the zone melting method is used. It implies that at a certain point in time only a certain zone of the total area of the metal is molten. Gradually moving, this zone redistributes impurities, as a result of which they ultimately accumulate in one place and can be easily removed from the alloy structure.
Finished tungsten arrives at the warehouse in the form of bars or ingots, intended for the subsequent production of the desired products. To obtain tungsten alloys, all constituent elements are crushed and mixed in powder form in the required proportions. Next, sintering and melting are carried out in an electric furnace.
Source: https://promplace.ru/vidy-metallov-i-klassifikaciya-staty/samyi-tugoplavkii-metall-1551.htm
