The most refractory metal.

Metals - this is the most common material (along with plastics and glass), which is used by people since ancient times.Even then, the man was known characteristics of the metal, it is advantageously used all their properties to create beautiful works of art, glassware, household items, plants.

One of the main features in the consideration of these substances is their hardness and high melting point.These qualities make it possible to determine the scope of use of the metal.Therefore, we consider all of the physical properties and particular attention is paid to the melting.

physical properties of metals

characteristics of metals in their physical properties can be expressed in the form of four key points.

1. metallic sheen - all have about the same silvery-white beautiful characteristic shine, except for copper and gold.They have red and yellow tide, respectively.Calcium - silver blue.
2. Appearance - all solid under normal conditions, except for mercury, which is in liquid form.
3. electrical and thermal conductivity - is characteristic of all metals, but is expressed in varying degrees.
4. malleability and ductility - also common to all metal setting, which is able to vary according to the particular representative.
5. melting point and boiling point - determines whether a refractory metal and a low melting point.This parameter is different for all items.

All physical properties are explained by the special structure of the metal lattice.Its spatial location, shape and strength.

fusible and refractory metals

This parameter is very important when it comes to the applications of the substances.Refractory metals and alloys - is the basis of mechanical engineering and shipbuilding, smelting and casting of many important products to quality working tool.Therefore, knowledge of melting and boiling points is fundamental.

Characterizing metal strength can divide them into hard and brittle.If you talk about refractoriness, here distinguish two main groups:

1. Fusible - are those that are able to change the physical state at temperatures below 1000 ° C.Examples include tin, lead, mercury, sodium, cesium, manganese, zinc, aluminum, and others.
2. refractory are those whose melting point above the designated size.There are not many, but in practice is used even less.

Table metal having a melting point above 1000 ° C, is presented below.It is there and arranged the most refractory representatives.

This table metal comprisesan all representatives, whose melting point above 1000 ° C.However, in practice many of them are used for various reasons.For example, because of economic benefits due to radioactive or too high brittleness exposure corrosivity.

also evident from the Table that the most refractory metal in the world - is tungsten.The lowest figure for gold.When working with metals is important softness.Therefore, many of the mentioned above are not used for industrial purposes.

most refractory metal - tungsten

in the periodic system is under the ordinal number 74. The name is derived by the name of the famous physicist Stephen Wolfram.Under normal conditions is a solid refractory metal silver-white color.It has a pronounced metallic sheen.Substantially chemically inert in the reaction takes reluctantly.

In nature, found in the form of minerals:

• wolframite;
• scheelite;
• Gyubnera;
• ferberite.

Scientists have proved that the tungsten - the most refractory metal of all.However, there are suggestions that seaborgium theoretically able to break the record of this metal.But he is a radioactive element with a very short period of existence.Therefore, it is impossible to prove.

At a certain temperature (above 1500 ° C), tungsten becomes malleable and ductile.Therefore possible to produce a thin wire on its basis.This property is used for the production of filaments in ordinary household light bulbs.

As the most refractory metal, withstands temperatures over 3400 ° C, tungsten is used in the following fields of technology:

• as an electrode in the argon welding;
• for acid-resistant, wear-resistant and heat-resistant alloys;
• as a heating element;
• in vacuum tubes as the filament and so on.

addition to tungsten metal, widely used in engineering, science and electronics its compounds.As the refractory metal in the world and it forms a compound with a very high-quality features: durable, resistant to almost all types of chemical exposure is not subject to corrosion, can withstand low and high temperatures (win, tungsten sulphide, its single crystals and other substances).

niobium and its alloys

Nb, or niobium, - under normal conditions, a silvery-white lustrous metal.He is also refractory, as the transition temperature to a liquid state for him is 2477 ° C.It is this quality, as well as the combination of low reactivity and allows niobium superconductivity is becoming more popular in practical human activity every year.Today, this metal is used in industries such as:

• rocket science;
• aerospace industry;
• nuclear energy;
• chemical EQUIPMENT;
• radio technology.

The metal retains its physical properties even at very low temperatures.Based articles characterized by high corrosion resistance, heat resistance, strength and excellent conductivity.

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

Tantalum metal in free form, and under normal conditions covered by the oxide film.It has a set of physical properties that allow it to be widespread and very important for people.Its main characteristics are as follows:

1. At temperatures above 1000 ° C becomes a superconductor.
2. This is the most refractory metal after the tungsten and rhenium.The melting point is 3017 ° C.
3. perfectly absorbs gases.
4. easy to work with him as he rolled in layers, foil and wire easily.
5. has good hardness and brittle, retains ductility.
6. very resistant to chemical agents (insoluble even in aqua regia).

These characteristics managed to gain popularity as a basis for many high-temperature and acid, corrosion-resistant alloys.His numerous compounds are used in nuclear physics, electronics, computing devices plan.They are used as superconductors.Previously, tantalum used as an element in incandescent lamps.Now he was replaced by tungsten.

Chromium and its alloys

One of the hardest metal in the form of a natural bluish-white color.Its melting point is lower than that considered until now the elements and is 1907 ° C.However, it is still used in the art and industry throughout as well amenable to mechanical stress, and processed forms.

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

chromium alloys are very popular.Even a small amount of this metal in the alloy increases the hardness and resistance to the effects of the latter.

Zirconium

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

Under normal conditions, this is a beautiful silvery-white metal.It has a relatively high melting point - 1855 ° C.It has good hardness, corrosion resistance, since the chemical is not enabled.Also exhibits excellent biological compatibility with the human skin and the whole organism.This makes it a valuable metal for use in medicine (tools, prostheses, and so on).

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

• nuclear power;
• pyrotechnics;
• alloying of metals;
• medicine;
• manufacturing bioposudy;
• construction material;
• like a superconductor.

zirconium and its alloys are made even decorations that can influence the improvement of human health.

Molybdenum

If you find out what the most refractory metals, in addition to the designated tungsten and molybdenum can be called.Its melting point is 2623 ° C.At the same time it is quite hard, ductile and treatable.

used it basically not in pure form, but as an integral component of the alloy.They are due to the presence of molybdenum is much stronger in the durability, heat resistance and corrosion.

Some molybdenum compounds used as lubricant specifications.Also, the metal alloying material is simultaneously affects the strength, anticorrosion and that is very rare.

Vanadium

gray metal with a silvery sheen.It has a fairly high rate of melting (1920 ° C).It used mainly as a catalyst in many processes, due to its inertia.It is used in the power industry as a chemical current source in the production of inorganic acids.The main importance is not pure metal, namely some of its compounds.

Rhenium and its alloys

What is the most refractory metal tungsten after?It rhenium.Its melting rate is 3186 ° C.On the strength of superior and tungsten, and molybdenum.Plasticity it is not too high.The demand for rhenium is very large, but the production is the complexity.Because of this, it is the most expensive metal in existence today.

used for manufacturing:

• jet engines;
• thermocouples;
• filaments for spectrometers and other devices;
• as a catalyst in the refining sector.

all areas of expensive, so it is used only in case of emergency, when to replace something else can not.

Titanium alloys

Titan - it is very lightweight metal silver-white color, which is widely used in the metallurgical industry and metal.May explode when in a finely divided state, so is a fire hazard.

used in aircraft and rocket production, the production of ships.Widely used in medicine because of biocompatibility with the body (artificial limbs, piercings, implants, etc.).