Metals - a large group of simple elements with characteristics such as high thermal and electrical conductivity, a positive temperature coefficient and more.To properly classify and understand what's what, you need to understand all the nuances.Let's try with you to consider the following main types of metals such as ferrous, non-ferrous, precious and alloys.It is quite extensive and complex subject, but we'll try to break it down.
What everyone should know?
Before classifying metals in groups, you need to understand the basic features.To include primary negative factor conduction of electricity.This suggests that as the temperature decreases the conductivity increases, some conductors become superconductors.At the same time, an increase in temperature leads to partial or complete loss of capacity.The secondary features necessary to include a metallic luster and a high melting point.In addition, some metals form compounds act as a reducing agent in redox reactions.Notice that the nature of pure metals practically do not occur, so forget ore and nuggets is also not necessary.
About ferrous metals
This group includes iron and its alloys (cast iron, ferroalloys).In fact, ferrous metals - an alloy of iron with carbon, but apart from that in the composition there are also other chemical elements, such as sulfur, phosphorus, silicon and others. If necessary to give an alloy the specific properties required for specific purposes, are added dopants inAs it appears most frequently copper, chromium or nickel.Classifies all kinds of ferrous metals on the carbon content.So, the following alloys:
- Iron - the amount of carbon ranges from 2 to 4.3%, in some cases reaches the critical level of 5%.Various chemical elements directly affect the properties of the product.For example, sulfur and phosphorus increase the fragility and chrome and nickel additives make iron more resistant and resistant to corrosion.
- steel - carbon content of up to 2%.It differs from the iron high ductility and high technological performance (easier to process).
Features of iron and steel in detail
Currently, there are several types of cast iron, which are used in everyday life, as well as industry: Foundry (gray) and pig (white).The latter differ from the first type in that the carbon is bound in the form of cement in the first case - in the free state in the form of graphite.Lowering the strength of this material is due to the fact that the plate graphite violate metal structure, thereby weakening it.There is a modified cast iron.Its features are that the graphite is in a spherical shape, which improves the mechanical properties of the product.
you probably already understand, that have become more universal, that is due not so much carbon in the composition.Thus, structural steels contain 0.02 to 0.85% carbon, and used for construction.Their main advantage is good ductility.Low degree of brittleness.There are tools in which the carbon content is slightly higher - of 0.65 to 1.4%, therefore, it is more durable alloy, but fragile.It is used as the name implies, as a template for the creation of tools (cutting, sawing machines and working bodies of the units).Here we examined the kinds of ferrous metals, so let's go further.
Precious metals This group includes chemical resistant, does not oxidize in air, water and alloys.It is worth noting that the amount of these metals on the planet is relatively small, and the process of extraction and processing of extremely complex and time-consuming.If humanity knew long ago all of the 7 groups, today there are several more.Thus, most known types of precious metals as gold, silver, platinum, osmium, rhodium, palladium, iridium, and others. All of them occur in nature.There are also so-called isotopes.They are produced in laboratories by complex chemical reactions.The most expensive of such metal - californium-252 cost 500 thousand dollars per gram.The most popular include the osmium-187 produced in modern laboratories.
about silver and gold
Ever since the Stone Age people are familiar with a metal such as gold.It's safe to say that this is the most important precious metal in the world.In nature, most often it occurs as nuggets with a small amount of impurities in the alloy or silver.The exclusive features include thermal conductivity and is a very low resistance.Of course, it should be noted malleability of gold, which is why it is a very popular material for the manufacture of jewelry.An interesting fact: the largest gold nugget was found in Australia.It weighed about 90 kilograms.
If we consider the main types of precious metals, one can not say about the silver.The nature of the material found in the native form (silver ore).But it is worth noting that the bulk of the production is carried out complex ores where silver is relatively little, but deposits of minerals are more common.This is a very soft and ductile metal that has excellent electrical and thermal conductivity.
Rhodium and platinum
Rhodium - a metal that does not have its own minerals, is therefore one of the most expensive.For programs will have to pay more than 220 dollars.This precious metal is silver with a bluish tint.Distinguished by its resistance to chemical and thermal influences, but it is extremely vulnerable to mechanical damage due to its fragility.As is quite expensive, it is used only where you can not pick up analogue.
If we consider the types and kinds of metals, it can not be said of platinum, opened in 1952 by the Swedish chemist.This is a rare material and is found in nature only in combination with other metal alloys.The process of production is extremely time consuming and requires large investments, but it's worth it, because platinum does not act any one known to date acid.When heated, the color does not change and is not oxidized.
Types of non-ferrous metals
This group is the most popular, since most of the material is a raw material for production of rolled metal products.If we talk about the scope, it is quite extensive, it is mechanical engineering, metallurgy, electronics, high technology and so on. D. On the physical properties are the following types of non-ferrous metals:
- heavy (lead, zinc, tin, nickel, etc..);
- light (aluminum, titanium, magnesium, etc.).
According to this classification, there are light metals and heavy metals.It is no secret that from this group can be made completely any technique.Note that a color to include all types of metal alloys, except iron.And now let's move on.
The main types of heavy metals
Today, there are about 40 definitions of this group of materials.The distinctive features - impressive atomic weight, usually more than 50. From this it can be concluded that the list should include everything that comes after the vanadium (regardless of density).But if we use a different definition, the determining parameter may be a density which should be more than that of iron (8 g / cm3).In this case, the list will lead, mercury, copper, tin and here would be for a list.Today it is extremely acute problem of environmental pollution by the group.This is because many metals are used in heavy industry and fall into the ocean together with wastewater.The main problem - is the high toxicity of mercury, lead, cadmium.In addition, some types of heavy metals have feature bioaccumulate.So, because of mercury poisoning in 1977, there were more than 2,300 casualties.
Mercury, lead and cadmium
This is the most dangerous non-ferrous metals, related to severe.They are the main polluters.The mercury - a highly toxic metal to humans, the ocean falls through the atmosphere and with sewage.When coal is burned in power plants, the mercury compounds released into the atmosphere, and then fall into the ocean in the form of precipitation.In addition, many freshwater and marine species accumulate in its body a significant amount of mercury that is not once led to poisoning of humans and even death.
Cadmium - scattered and fairly rare element, which falls into the ocean together with sewage metallurgical and ore-dressing plants.It should be noted that cadmium is present in the human body, but it is very small.In chronic poisoning broken bones, and anemia starts.With regard to lead, the metal in the dispersed state is practically everywhere.These kinds of metal photo of which we quoted above, removed from the body, but rather slowly, so their excessive amount causes serious health problems.Along with continental dust into the ocean together with atmospheric precipitation falls of about 25 thousand tons of lead.
Note
As you can see, there are a variety of types and properties of metals.Something is not dangerous, and every day we wear a silver cross and a gold ring on his hand.Radioactive substances can kill a man, so environmentalists all over the world are trying to partly solve the problem of emission of dangerous metals in the ocean and atmosphere.Of course, to solve such problems is very difficult, especially given the fact that most entrepreneurs do not go to the contact.Nevertheless, we should not forget that without conductors, which consist of the same metal, possible wiring diagrams, and without iron will not machines and other usual things for us.
We have not been affected by a group of so-called radioactive metals of the periodic table.These include technetium, polonium, promethium, and others. The main purpose - to use in nuclear reactors and weapons, which makes them very dangerous.
Conclusion
You probably noticed that there are a variety of types of metals.In nature, most of them are present in a variety of ores and forms sulfides, carbonates and other chemical compounds.For pure metals and their further application using modern technological treatment and processing lines.I'm sure you will be interested to know that the human body also contains a small amount of metal compounds - about 3%.Thus, in the bones have a calcium, iron in the blood, muscle constantly accumulates magnesium and copper in the liver have.
Well, in principle, all that can be said about what are the different types of metal alloys.Despite the fact that it is quite a complex topic, it may be of interest to those interested in metallurgy.
