The most refractory metal. Characteristics of metals

Metals are the most common material (along with plastics and glass), which has been used by people since ancient times. Even then, a person knew the characteristics of metals, he profitably used all their properties to create beautiful works of art, dishes, household items, 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 scope of use of a particular metal. Therefore, we 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.

1. Metallic shine - all have about the same silvery white beautiful characteristic shine, except for copper and gold. They have a reddish and yellow tint, respectively. Calcium is a silver-blue.
2. Aggregate state - all solid under normal conditions, except mercury, which is in the form of a liquid.
3. Electrical and thermal conductivity - is typical for all metals, but is expressed in different degrees.
4. Kovkost and plasticity is also a common parameter for all metals, which can vary depending on the particular representative.
5. The melting point and the boiling point - determines 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 metallic crystal lattice. Its spatial arrangement, shape and strength.

Low-melting and refractory metals

This parameter is very important when it comes to the application of the substances in question. Refractory metals and alloys are the basis of machine and shipbuilding, smelting and casting of many important products, obtaining a quality working tool. Therefore, the knowledge of the melting and boiling points plays a fundamental role.

Characterizing the metals in strength, they can be divided into hard and brittle. If we talk about refractory, then there are two main groups:

1. The fusible ones are those that are capable of changing the aggregate state at temperatures below 1000 ° C. Examples are: tin, lead, mercury, sodium, cesium, manganese, zinc, aluminum and others.
2. Refractory are those whose melting point is above the indicated value. There are not so many, but in practice, even less.

Table of metals having a melting point above 1000 ° C is presented below. It is in it that the most refractory representatives are located.

This table of metals includes all representatives whose melting point is above 1000 ^o C. However, in practice, many of them are not used for various reasons. For example, due to economic benefits or due to radioactivity, too high a degree of brittleness, exposure to corrosive effects.

It is also clear from the table that the most refractory metal in the world is tungsten. The lowest indicator for gold. When working with metals, softness is important. Therefore, many of the above are also not used for technical purposes.

The most refractory metal is tungsten

In the periodic system it is located under the serial number 74. The name was given by the name of the famous physicist Stephen Wolfram. Under normal conditions, a solid refractory metal is silvery white. Has a pronounced metallic luster. It is chemically practically inert, reacting reluctantly.

In nature it is contained in the form of minerals:

• wolframite;
• Scheelite;
• Gyubnerite;
• Ferberite.

Scientists have proved that tungsten is the most refractory metal of all existing. However, there are suggestions that the siborgy can theoretically break the record of this metal. But it is a radioactive element with a very short period of existence. Therefore, it is not yet possible to prove this.

At a certain temperature (above 1500 ° C) tungsten becomes ductile and ductile. Therefore, it is possible to produce a thin wire based on it. This property is used for making filaments in ordinary household light bulbs.

As the most refractory metal withstanding temperatures above 3400 ° C, tungsten is used in the following technical fields:

• As electrode with argon welding;
• For the production of acid-resistant, wear-resistant and heat-resistant alloys;
• As a heating element;
• In vacuum tubes like filament and so on.

In addition to metallic tungsten, it is widely used in engineering, science and electronics of its connection. As the most refractory metal in the world, it forms compounds with very high quality characteristics: durable, resistant to virtually all types of chemical attack, not corroded, withstand low and high temperatures (wins, tungsten sulfide, its single crystals and other substances).

Niobium and its alloys

Nb, or niobium, under normal conditions, a silvery-white shiny metal. It is also refractory, since the temperature of transition to a liquid state for it is 2477 ° C. It is this quality, as well as a combination of low chemical activity and superconductivity that allows niobium to become increasingly popular in a person's practical activity every year. Today this metal is used in such industries as:

• Rocket engineering;
• Aviation and space industry;
• nuclear power;
• Chemical apparatus engineering;
• radio engineering.

This metal retains its physical properties even at very low temperatures. Products based on it are distinguished by corrosion resistance, heat resistance, strength, excellent conductivity.

This metal is added to the aluminum materials to improve chemical resistance. From it, cathodes and anodes are made, they are alloyed with non-ferrous alloys. Even coins in some countries do with the content of niobium.

Tantalum

Metal, in free form and under ordinary conditions covered with oxide film. Has a set of physical properties that allow it to be widespread and very important for humans. Its main characteristics are as follows:

1. At temperatures above 1000 ^o C becomes a superconductor.
2. This is the most refractory metal after tungsten and rhenium. The melting point is 3017 ° C.
3. Perfectly absorbs gases.
4. It is easy to work with, since it is rolled into layers, foil and wire without much difficulty.
5. Has good hardness and is not brittle, retains ductility.
6. It is very resistant to chemical agents (it does not dissolve even in royal vodka).

Due to such characteristics it managed to gain popularity as a basis for many heat-resistant and acid-resistant, anticorrosive alloys. Its numerous compounds find application in nuclear physics, electronics, computational plan devices. Used as superconductors. Previously, tantalum was used as an element in incandescent lamps. Now his place was taken by tungsten.

Chrome and its alloys

One of the hardest metals in the natural form of a bluish-white color. Its melting point is lower than that of the elements considered so far, and is 1907 ° C. However, it is still used in engineering and industry everywhere, as it is well amenable to mechanical influences, processed and molded.

Especially valuable is chrome as a spray. It is applied to products to give them a beautiful shine, protection against corrosion and increase wear resistance. The process is called chrome plating.

The chromium alloys are very popular. After all, even a small amount of this metal in the alloy significantly increases the hardness and stability of the latter to impacts.

Zirconium

One of the most expensive metals, so its use for technical purposes is difficult. However, physical characteristics make it simply irreplaceable in many other industries.

Under normal conditions, this is a beautiful silvery-white metal. It has a sufficiently high melting point - 1855 ° C. It has good hardness, resistance to corrosion, since it is not chemically active. It also has excellent biological compatibility with human skin and the body as a whole. This makes it a valuable metal for use in medicine (tools, dentures and so on).

The main applications of zirconium and its compounds, including alloys, are as follows:

• nuclear energy;
• pyrotechnics;
• Alloying of metals;
• medicine;
• The manufacture of biovacuum;
• Structural material ;
• As a superconductor.

Of zirconium and alloys based on it, even decorations are made that can influence the improvement of human health.

Molybdenum

If we find out which metal is the most refractory, then, in addition to the tungsten, it is possible to name molybdenum. Its melting point is 2623 ° C. At the same time, it is sufficiently hard, plastic and can be processed.

It is used mainly not in pure form, but as a component component of alloys. They, thanks to the presence of molybdenum, are significantly strengthened in wear resistance, heat resistance and anti-corrosion.

Some molybdenum compounds are used as technical lubricants. Also, this metal is a doping material, which simultaneously affects both strength and anticorrosion, which is very rare.

Vanadium

Gray metal with silvery sheen. It has a sufficiently high melting index (1920 ^о С). It is used mainly as a catalyst in many processes, due to its inertness. It is used in power engineering as a chemical source of current, in the production of inorganic acids. The main importance is not pure metal, but some of its compounds.

Rhenium and alloys based on it

Which metal is the most refractory after tungsten? This is rhenium. Its fusibility rate is 3186 ^o C. It is stronger than tungsten and molybdenum in strength. Its plasticity is not too high. Demand for rhenium is very high, but production is difficult. As a consequence, it is the most expensive metal available today.

It is used for manufacturing:

• Jet engines;
• Thermocouples;
• Filament for spectrometers and other devices;
• As a catalyst in oil refining.

All areas of use are expensive, so it is only used in case of emergency, when there is no other option to replace it.

Titanium alloys

Titanium is a very light silver-white metal, which is widely used in the metallurgical industry and metalworking. May explode when in a finely dispersed state, therefore it is a fire hazard.

It is used in aircraft and rocket construction, in the production of ships. It is widely used in medicine due to its biological compatibility with the body (prostheses, piercings, implants, etc.).