titanium alloys. Main characteristics

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The thermal conductivity of titanium is - 14 0 W / m deg, which is somewhat lower than the thermal conductivity of alloy steel. The material is well forged, stamped, machined. Titanium products are welded with a tungsten electrode in a protective argon atmosphere. Recently, titanium has been used for the manufacture of a wide range of pipes, sheets, rolled products.

The thermal conductivity of titanium is low - about 13 times lower than aluminum and 4-4 times lower than iron.

The thermal conductivity of titanium is close to that of stainless steel and is 14 kcal/m C hour. Titanium is well forged, stamped and machined satisfactorily. At temperatures above 200 C, it tends to absorb gases. Titanium is welded with a tungsten electrode in a protective argon atmosphere.

The thermal conductivity of titanium and its alloys is approximately 15 times lower than that of aluminum, and 35-5 times lower than that of steel. The coefficient of linear thermal expansion of titanium is also significantly lower than that of aluminum and stainless steel.

The thermal conductivity of titanium is - 14 0 W / (m - K), which is somewhat lower than the thermal conductivity of alloy steel. The material is well forged, stamped, machined. Titanium products are welded with a tungsten electrode in a protective argon atmosphere. Recently, titanium has been used for the manufacture of a wide range of pipes, sheets, rolled products.

The thermal conductivity coefficient of titanium in the operating temperature range (20 - 400 C) is 0 057 - 0 055 cal / (cm-s - C), which is about 3 times less than the thermal conductivity of iron, 16 times less than the thermal conductivity of copper and close to the thermal conductivity of stainless steels austenitic grade.

Therefore, for example, the thermal conductivity of titanium is 8 - 10 times less than the thermal conductivity of aluminum.

The obtained calculated values ​​of the phonon thermal conductivity of titanium coincide with the estimate of this value made in the work, where it is taken equal to 3 -: - 5 W / m-deg.

With alloying, as well as with an increase in the content of impurities, the thermal conductivity of titanium, as a rule, decreases. When heated, the thermal conductivity of alloys, like pure titanium, increases; already at 500 - 600 C, it approaches the thermal conductivity of unalloyed titanium.

The modulus of elasticity of titanium is almost half that of iron, is on the same level with the modulus of copper alloys and is much higher than that of aluminum. The thermal conductivity of titanium is low: it is about 7% of the thermal conductivity of aluminum and 165% of the thermal conductivity of iron. This must be taken into account when heating metal for forming and welding. The electrical resistance of titanium is about 6 times greater than that of iron and 20 times greater than that of aluminum.

First of all, it must be taken into account that the thermal conductivity of titanium and its alloys at low temperatures is very low. At room temperature, the thermal conductivity of titanium is approximately 3% of the thermal conductivity of copper and is several times lower than, for example, that of steels (the thermal conductivity of titanium is 0 0367 cal / cm sec C, and the thermal conductivity of steel 40 is 0 142 cal. With increasing temperature, the thermal conductivity of titanium alloys increases and approaches the thermal conductivity of steels.This affects the heating rates of titanium alloys depending on the temperature to which they are heated, as can be seen from the heating and cooling rates of commercially pure titanium (VT1 alloy) with a cross section of 150 mm (Fig.

Titanium has a low thermal conductivity, which is 13 times less than the thermal conductivity of aluminum and 4 times less than the thermal conductivity of iron. With an increase in temperature, the thermal conductivity of titanium decreases somewhat and at 700 C it is 0 0309 cal/cm sec SS.

Titanium has a low thermal conductivity, which is 13 times less than the thermal conductivity of aluminum and 4 times less than the thermal conductivity of iron. With an increase in temperature, the thermal conductivity of titanium decreases somewhat and at 700 C it is 0 0309 cal / cm sec C.

In fusion welding, to obtain a good quality joint, reliable protection from atmospheric gases (O2, Nj, H2) of the metal of the welded joint heated to a temperature above 400 C on both sides of the weld is necessary. Grain growth is exacerbated by the low thermal conductivity of titanium, which increases the residence time of the weld metal at high temperatures. To overcome these difficulties, welding is performed at the lowest possible heat input.

Many are interested in a slightly mysterious and not fully understood titanium - a metal whose properties are somewhat ambiguous. Metal is both the strongest and the most brittle.

The strongest and most brittle metal

It was discovered by two scientists with a difference of 6 years - the Englishman W. Gregor and the German M. Klaproth. The name of the titan is associated, on the one hand, with the mythical titans, supernatural and fearless, on the other hand, with Titania, the queen of the fairies.
This is one of the most common materials in nature, but the process of obtaining a pure metal is particularly difficult.

22 chemical element of D. Mendeleev's table Titanium (Ti) belongs to the 4th group of the 4th period.

The color of titanium is silvery white with a pronounced luster. Its highlights shimmer with all the colors of the rainbow.

It is one of the refractory metals. It melts at +1660°C (±20°). Titanium is paramagnetic: it is not magnetized in a magnetic field and is not pushed out of it.
The metal is characterized by low density and high strength. But the peculiarity of this material lies in the fact that even minimal impurities of other chemical elements radically change its properties. In the presence of an insignificant fraction of other metals, titanium loses its heat resistance, and a minimum of non-metallic substances in its composition make the alloy brittle.
This feature determines the presence of 2 types of material: pure and technical.

1. Pure titanium is used where a very light substance is required that can withstand heavy loads and ultra-high temperature ranges.
2. Technical material is used where parameters such as lightness, strength and resistance to corrosion are valued.

The substance has the property of anisotropy. This means that the metal can change its physical characteristics based on the applied force. This feature should be taken into account when planning the use of the material.

Titanium loses its strength at the slightest presence of impurities of other metals in it.

Conducted studies of the properties of titanium under normal conditions confirm its inertness. The substance does not react to elements in the surrounding atmosphere.
The change in parameters begins when the temperature rises to +400°C and above. Titanium reacts with oxygen, can ignite in nitrogen, absorbs gases.
These properties make it difficult to obtain a pure substance and its alloys. Titanium production is based on the use of expensive vacuum equipment.

Titanium and competition with other metals

This metal is constantly compared with aluminum and iron alloys. Many of the chemical properties of titanium are significantly better than those of competitors:

1. In terms of mechanical strength, titanium surpasses iron by 2 times, and aluminum by 6 times. Its strength increases with decreasing temperature, which is not observed in competitors.
   Anticorrosive characteristics of titanium are significantly higher than those of other metals.
2. At ambient temperatures, the metal is absolutely inert. But when the temperature rises above +200°C, the substance begins to absorb hydrogen, changing its characteristics.
3. At higher temperatures, titanium reacts with other chemical elements. It has a high specific strength, which is 2 times higher than the properties of the best iron alloys.
4. The anti-corrosion properties of titanium significantly exceed those of aluminum and stainless steel.
5. The substance is a poor conductor of electricity. Titanium has a resistivity 5 times that of iron, 20 times that of aluminum, and 10 times that of magnesium.
6. Titanium is characterized by low thermal conductivity, this is due to the low coefficient of thermal expansion. It is 3 times less than that of iron, and 12 times less than that of aluminum.
   

How is titanium obtained?

The material takes 10th place in terms of distribution in nature. There are about 70 minerals containing titanium in the form of titanic acid or its dioxide. The most common of them and containing a high percentage of metal derivatives:

• ilmenite;
• rutile;
• anatase;
• perovskite;
• brookite.

The main deposits of titanium ores are located in the USA, Great Britain, Japan, large deposits of them are discovered in Russia, Ukraine, Canada, France, Spain, Belgium.

Titanium mining is an expensive and labor-intensive process

Getting metal from them is very expensive. Scientists have developed 4 ways to produce titanium, each of which is working and effectively used in industry:

1. Magnesium method. The extracted raw materials containing titanium impurities are processed and titanium dioxide is obtained. This substance is subjected to chlorination in mine or salt chlorinators at elevated temperatures. The process is very slow and is carried out in the presence of a carbon catalyst. In this case, solid dioxide is converted into a gaseous substance - titanium tetrachloride. The resulting material is reduced by magnesium or sodium. The alloy formed during the reaction is subjected to heating in a vacuum unit to ultrahigh temperatures. As a result of the reaction, evaporation of magnesium and its compounds with chlorine occurs. At the end of the process, a sponge-like material is obtained. It is melted and high quality titanium is obtained.
2. Hydride-calcium method. The ore is subjected to a chemical reaction and titanium hydride is obtained. The next stage is the separation of the substance into components. Titanium and hydrogen are released during heating in vacuum plants. At the end of the process, calcium oxide is obtained, which is washed with weak acids. The first two methods relate to industrial production. They make it possible to obtain pure titanium in the shortest possible time at relatively low costs.
3. electrolysis method. Titanium compounds are subjected to high current. Depending on the feedstock, the compounds are divided into components: chlorine, oxygen and titanium.
4. Iodide method or refining. Titanium dioxide obtained from minerals is doused with iodine vapor. As a result of the reaction, titanium iodide is formed, which is heated to a high temperature - + 1300 ... + 1400 ° C and act on it with an electric current. At the same time, components are isolated from the source material: iodine and titanium. The metal obtained by this method has no impurities and additives.

Areas of use

The use of titanium depends on the degree of its purification from impurities. The presence of even a small amount of other chemical elements in the titanium alloy radically changes its physical and mechanical characteristics.

Titanium with a certain amount of impurities is called technical. It has high rates of corrosion resistance, it is light and very durable material. Its application depends on these and other indicators.

• In the chemical industry titanium and its alloys are used to manufacture heat exchangers, pipes of various diameters, fittings, housings and parts for pumps for various purposes. The substance is indispensable in places where high strength and resistance to acids are required.
• On transport titanium is used for the manufacture of parts and assemblies of bicycles, cars, railway cars and trains. The use of the material reduces the weight of rolling stock and cars, makes bicycle parts lighter and stronger.
• Titanium is important in the naval department. Parts and elements of hulls for submarines, propellers for boats and helicopters are made from it.
• In the construction industry zinc-titanium alloy is used. It is used as a finishing material for facades and roofs. This very strong alloy has an important property: it can be used to make architectural details of the most fantastic configuration. It can take any form.
• In the last decade, titanium has been widely used in the oil industry. Its alloys are used in the manufacture of equipment for ultra-deep drilling. The material is used for the manufacture of equipment for oil and gas production on the offshore shelves.

Titanium has a very wide range of applications.

Pure titanium has its uses. It is needed where resistance to high temperatures is required and at the same time the strength of the metal must be maintained.

It is applied in :

• aircraft and space industry for the manufacture of skin parts, hulls, fasteners, chassis;
• medicine for prosthetics and the manufacture of heart valves and other devices;
• technique for working in the cryogenic area (here they use the property of titanium - with a decrease in temperature, the strength of the metal increases and its plasticity is not lost).

In percentage terms, the use of titanium for the production of various materials looks like this:

• 60% is used for the manufacture of paint;
• plastic consumes 20%;
• 13% is used in paper production;
• mechanical engineering consumes 7% of the resulting titanium and its alloys.

Raw materials and the process of obtaining titanium are expensive, the costs of its production are compensated and paid off by the service life of products from this substance, its ability not to change its appearance over the entire period of operation.

Everything you need to know about titanium as well as chromium and tungsten

Many are interested in the question: what is the hardest metal in the world? This is a titan. This solid substance will be the subject of most of the article. We will also get a little acquainted with such hard metals as chromium and tungsten.

9 interesting facts about titanium

1. There are several versions of why the metal got its name. According to one theory, he was named after the Titans, fearless supernatural beings. According to another version, the name comes from Titania, the queen of the fairies.
2. Titanium was discovered at the end of the 18th century by a German and English chemist.
3. Titanium has not been used in industry for a long time due to its natural brittleness.
4. At the beginning of 1925, after a series of experiments, chemists obtained pure titanium.
5. Titanium shavings are flammable.
6. It is one of the lightest metals.
7. Titanium can only melt at temperatures above 3200 degrees.
8. Boils at a temperature of 3300 degrees.
9. Titanium has a silver color.

The history of the discovery of titanium

The metal, which was later called titanium, was discovered by two scientists - the Englishman William Gregor and the German Martin Gregor Klaproth. Scientists worked in parallel, and did not intersect with each other. The difference between the discoveries is 6 years.

William Gregor named his discovery menakin.

More than 30 years later, the first titanium alloy was obtained, which turned out to be extremely brittle and could not be used anywhere. It is believed that only in 1925 titanium was isolated in its pure form, which became one of the most demanded metals in industry.

It is proved that the Russian scientist Kirillov in 1875 managed to extract pure titanium. He published a pamphlet detailing his work. However, the research of a little-known Russian went unnoticed.

General information about titanium

Titanium alloys are a lifesaver for mechanics and engineers. For example, the body of an aircraft is made of titanium. During the flight, it reaches speeds several times greater than the speed of sound. The titanium case heats up to temperatures above 300 degrees, and does not melt.

Metal closes the top ten "Most common metals in nature." Large deposits have been discovered in South Africa, China, and a lot of titanium in Japan, India, and Ukraine.

The total amount of the world's titanium reserves is more than 700 million tons. If the rate of production remains the same, titanium will last another 150-160 years.

The largest producer of the hardest metal in the world is the Russian enterprise VSMPO-Avisma, which satisfies a third of the world's needs.

Titanium properties

1. Corrosion resistance.
2. High mechanical strength.
3. Low density.

The atomic weight of titanium is 47.88 amu, the serial number in the chemical periodic table is 22. Outwardly, it is very similar to steel.

The mechanical density of the metal is 6 times higher than that of aluminum, 2 times higher than that of iron. It can combine with oxygen, hydrogen, nitrogen. When paired with carbon, the metal forms incredibly hard carbides.

The thermal conductivity of titanium is 4 times less than that of iron, and 13 times less than that of aluminum.

Titanium mining process

There is a large amount of titanium in the earth, however, it costs a lot of money to extract it from the bowels. For development, the iodide method is used, the author of which is Van Arkel de Boer.

The method is based on the ability of the metal to combine with iodine; after the decomposition of this compound, pure titanium, free from impurities, can be obtained.

The most interesting things from titanium:

• prostheses in medicine;
• mobile device boards;
• rocket systems for space exploration;
• pipelines, pumps;
• canopies, cornices, exterior cladding of buildings;
• most parts (chassis, skin).

Applications of titanium

Titanium is actively used in the military, medicine, and jewelry. He was given the unofficial name "metal of the future". Many say that it helps to turn a dream into reality.

The hardest metal in the world was originally used in the military and defense sphere. Today, the main consumer of titanium products is the aircraft industry.

Titanium is a versatile structural material. For many years it has been used to create aircraft turbines. In aircraft engines, titanium is used to make fan elements, compressors, and disks.

The design of a modern aircraft can contain up to 20 tons of titanium alloy.

The main areas of application of titanium in the aircraft industry:

• products of a spatial form (edging of doors, hatches, sheathing, flooring);
• units and components that are subject to heavy loads (wing brackets, landing gear, hydraulic cylinders);
• engine parts (body, blades for compressors).

Thanks to titanium, man was able to pass through the sound barrier and break into space. It was used to create manned missile systems. Titanium can withstand cosmic radiation, temperature changes, speed of movement.

This metal has a low density, which is important in the shipbuilding industry. Products made of titanium are light, which means that weight is reduced, its maneuverability, speed, and range are increased. If the ship's hull is sheathed with titanium, it will not need to be painted for many years - titanium does not rust in sea water (corrosion resistance).

Most often, this metal is used in shipbuilding for the manufacture of turbine engines, steam boilers, and condenser tubes.

Oil industry and titanium

Ultra-deep drilling is considered to be a promising area for the use of titanium alloys. To study and extract underground riches, there is a need to penetrate deep underground - over 15 thousand meters. Drill pipes made of aluminum, for example, will break due to their own gravity, and only titanium alloys can reach really great depths.

Not so long ago, titanium began to be actively used to create wells on the sea shelves. Specialists use titanium alloys as equipment:

• oil production installations;
• pressure vessels;
• deep water pumps, pipelines.

Titanium in sports, medicine

Titanium is extremely popular in the sports field because of its strength and lightness. A few decades ago, a bicycle was made from titanium alloys, the first sports equipment made from the hardest material in the world. A modern bicycle consists of a titanium body, the same brake and seat springs.

Japan has created titanium golf clubs. These devices are light and durable, but extremely expensive in price.

Titanium is used to make most of the items that are in the backpack of climbers and travelers - tableware, cooking kits, racks for strengthening tents. Titanium ice axes are a very popular sports equipment.

This metal is in high demand in the medical industry. Most surgical instruments are made of titanium - lightweight and comfortable.

Another area of ​​application of the metal of the future is the creation of prostheses. Titanium perfectly "combines" with the human body. Doctors called this process "true relationship." Titanium structures are safe for muscles and bones, rarely cause an allergic reaction, and do not break down under the influence of liquid in the body. Prostheses made of titanium are resistant and withstand enormous physical loads.

Titanium is an amazing metal. It helps a person to achieve unprecedented heights in various areas of life. It is loved and revered for its strength, lightness and long years of service.

Chromium is one of the hardest metals.

Interesting Chromium Facts

1. The name of the metal comes from the Greek word "chroma", which means paint.
2. In the natural environment, chromium does not occur in its pure form, but only in the form of chromium iron ore, a double oxide.
3. The largest metal deposits are located in South Africa, Russia, Kazakhstan and Zimbabwe.
4. Density of metal - 7200kg/m3.
5. Chromium melts at 1907 degrees.
6. Boils at a temperature of 2671 degrees.
7. Completely pure without impurities, chromium is characterized by malleability and toughness. In combination with oxygen, nitrogen or hydrogen, the metal becomes brittle and very hard.
8. This silver-white metal was discovered by the Frenchman Louis Nicolas Vauquelin at the end of the 18th century.

Chromium metal properties

Chrome has a very high hardness, it can cut glass. It is not oxidized by air, moisture. If the metal is heated, oxidation will occur only on the surface.

More than 15,000 tons of pure chromium are consumed per year. The British company Bell Metals is considered the leader in the production of the purest chromium.

Most chromium is consumed in the United States, Western Europe and Japan. The chromium market is volatile and prices span a wide range.

Areas of use of chromium

It is most often used to create alloys and electroplated coatings (chromium plating for transport).

Chromium is added to steel, which improves the physical properties of the metal. These alloys are most in demand in ferrous metallurgy.

The most popular steel grade consists of chromium (18%) and nickel (8%). Such alloys perfectly resist oxidation, corrosion, and are strong even at high temperatures.

Heating furnaces are made from steel, which contains a third of chromium.

What else is made of chrome?

1. Barrels of firearms.
2. Hull of submarines.
3. Bricks, which are used in metallurgy.

Another extremely hard metal is tungsten.

Interesting facts about tungsten

1. The name of the metal in German (“Wolf Rahm”) means “wolf foam”.
2. It is the most refractory metal in the world.
3. Tungsten has a light gray tint.
4. The metal was discovered at the end of the 18th century (1781) by the Swede Karl Scheele.
5. Tungsten melts at 3422 degrees, boils at 5900.
6. The metal has a density of 19.3 g/cm³.
7. Atomic mass - 183.85, element of group VI in the periodic system of Mendeleev (serial number - 74).

Tungsten mining process

Tungsten belongs to a large group of rare metals. It also includes rubidium, molybdenum. This group is characterized by a low prevalence of metals in nature and a small scale of consumption.

Getting tungsten consists of 3 stages:

• separation of metal from ore, its accumulation in solution;
• isolation of the compound, its purification;
• extraction of pure metal from the finished chemical compound.
• The starting material for obtaining tungsten is scheelite and wolframite.

Applications of tungsten

Tungsten is the basis of most durable alloys. Aircraft engines, parts of electrovacuum devices, incandescent filaments are made from it.
The high density of the metal makes it possible to use tungsten to create ballistic missiles, bullets, counterweights, artillery shells.

Tungsten-based compounds are used for the processing of other metals, in the mining industry (well drilling), paintwork, and textiles (as a catalyst for organic synthesis).

From complex tungsten compounds make:

• wires - used in heating furnaces;
• tapes, foil, plates, sheets - for rolling and flat forging.

Titanium, chromium and tungsten top the list of "The Hardest Metals in the World". They are used in many areas of human activity - aircraft and rocket science, the military field, construction, and at the same time, this is far from a complete range of metal applications.

DEFINITION

Titanium in the form of an ingot - a solid silver-white metal (Fig. 1), malleable and ductile, well machinable. However, even a small proportion of impurities dramatically changes its mechanical properties, making it harder and more brittle.

Rice. 1. Titanium. Appearance.

The main titanium constants are given in the table below.

Table 1. Physical properties and density of titanium.

Titanium has a hexagonal close-packed structure, which transforms into a body-centered cubic structure at high temperatures.

The prevalence of titanium in nature

In terms of prevalence in the earth's crust, titanium ranks ninth among all chemical elements. Its content in it is 0.63% (wt.). Titanium occurs in nature exclusively in the form of compounds. Of the titanium minerals, rutile TiO 2, ilmenite FeTiO 3, perovskite CaTiO 3 are of the greatest importance.

Brief description of the chemical properties and density of titanium

At ordinary temperatures, titanium in a compact form (i.e. in the form of ingots, thick wire, etc.) is corrosion resistant in air. For example, unlike iron-based alloys, it does not rust even in sea water. This is due to the formation of a thin but continuous and dense protective oxide film on the surface. When heated, the film is destroyed, and the activity of titanium noticeably increases. So, in an oxygen atmosphere, compact titanium ignites only at a white heat temperature (1000 o C), turning into TiO 2 oxide powder. Reactions with nitrogen and hydrogen proceed at approximately the same temperatures, but much more slowly, with the formation of TiN nitride and TiH 4 titanium hydride.

Ti + O 2 \u003d TiO 2;

2Ti + N 2 = 2TiN;

Ti + 2H 2 = TiH 4 .

The surface area of ​​titanium significantly affects the rate of oxidation reactions: thin titanium chips flare up when introduced into a flame, and very fine powders are pyrophoric - self-ignite in air.

The reaction with halogens begins at low heating and, as a rule, is accompanied by the release of a significant amount of heat, and titanium tetrahalides are always formed. Only in interaction with iodine requires higher (200 o C) temperatures.

Ti + 2Cl 2 \u003d TiCl 4;

Ti + 2Br 2 = TiBr 4 .

Examples of problem solving

EXAMPLE 1

EXAMPLE 2