Colored, precious and black types of metals and their characteristics

Metals are a large group of simple elements with characteristics such as high thermal and electrical conductivity, a positive temperature coefficient, and so on. To properly classify and understand what's what, you need to deal with all the nuances. Let's try with you to consider such basic types of metals as black, color, precious, and also alloys. This is quite an extensive and complex topic, but we will try to put everything in order.

What should everyone know?

Before classifying metals into groups, it is necessary to understand the main features. The negative conductivity coefficient of electricity is considered to be of primary importance. This suggests that as the temperature is lowered, the conductivity rises, and some conductors become superconductors. At the same time, a rise in temperature leads to a partial or total loss of throughput. To minor attributes, it is necessary to include metal shine, as well as high melting point. In addition, some metals in the form of compounds play the role of a reducing agent in oxidation-reduction reactions. Pay attention to the fact that in nature, pure metals practically do not occur, so forget about ore and nuggets, too, do not need.

About ferrous metals

This group includes iron, as well as its alloys (cast iron, ferroalloys). In fact, ferrous metals are an alloy of iron with carbon, but in addition there are other chemical elements in the composition, for example sulfur, phosphorus, silicon, etc. If it is necessary to give the alloy the specific properties necessary to fulfill certain goals, alloying substances are added, in Which are most often copper, chrome or nickel. All types of ferrous metals are classified by the content of carbon. So, there are the following alloys:

• Cast iron - the amount of carbon varies from 2 to 4.3%, in some cases reaches a critical level of 5%. Different chemical elements directly affect the properties of the product. Thus, sulfur with phosphorus increases brittleness, and chromium and nickel additives make cast iron more heat resistant and resistant to corrosion.
• Steel - the carbon content is up to 2%. It differs from cast iron with high plasticity, as well as high technological parameters (easier to process).

Peculiarities of cast iron and steel in details

Currently, there are several types of cast iron, which are used in everyday life, as well as in the industry: foundry (gray) and redundant (white). The latter differs from the first type in that the carbon is in the bound state in the form of cement, in the first case in the free state in the form of graphite. The reduction in strength of this material is due to the fact that graphite plates break the metal structure, thereby weakening it. There is a modified gray cast iron. Its features are that graphite is in a spherical shape, which increases the mechanical properties of the product.

You probably already knew that you became more versatile, which is not due to a large amount of carbon in the composition. So, structural steels contain from 0,02 to 0,85% of carbon and are used for construction. Their main advantage lies in good plasticity. The degree of brittleness is low. There are also instrumental, in which the carbon content is somewhat higher - from 0.65 to 1.4%, therefore, it is a more durable alloy, but brittle. Used, as can be understood from the name, as a workpiece for the creation of tools (cutting, sawing the working bodies of machines and aggregates). Here we have considered the types of ferrous metals, so let's go further.

Noble metals

This group includes chemically stable, not oxidized in water and air alloys. It should be noted that the amount of such metals on the whole planet is relatively small, and the extraction and processing process is extremely complex and time-consuming. If long ago mankind knew only about 7 groups, today there are a few more. Thus, the most famous types of precious metals: gold, silver, platinum, osmium, rhodium, palladium, iridium, etc. All of them are found in nature. Also there are so-called isotopes. They are obtained in laboratories through complex chemical reactions. The most expensive such metal is California-252 with a cost of 500 thousand dollars per gram. The most popular is osmium-187, obtained in modern laboratories.

About silver and gold

Since the Stone Age, people are familiar with metals such as gold. It can be said with certainty that this is the most important precious metal in the whole world. In nature it is most often found as nuggets with a small amount of impurities or in an alloy with silver. The exceptional features include thermal conductivity and very low resistance. Of course, we can not fail to note the malleability of gold, because of what it is extremely popular material for the manufacture of jewelry. An interesting fact: the largest gold nugget found in Australia. He hung about 90 kilograms.

If we consider the main types of precious metals, we can not say about silver. In nature, this material is found in native form (silver ore). But it is worth noting that the main extraction is carried out from complex ores, where there is relatively little silver, but deposits of such minerals are more common. This is a very soft and ductile metal that has exceptional electrical and thermal conductivity.

Rhodium and platinum

Rhodium is a metal that does not have its own minerals, therefore it is one of the most expensive. For a gram will have to pay more than 220 dollars. This noble metal has a silvery color with a bluish tint. It is distinguished by its resistance to chemical and temperature influences, but is extremely vulnerable to mechanical damage due to its fragility. Since it is quite expensive, it is used only where it is impossible to choose an analogue.

If we consider the types and types of metals, we can not say about platinum, discovered in 1952 by a Swedish chemist. This is a fairly rare material and is found in nature only in the combination of alloys with other metals. The extraction process is extremely laborious and requires large investments, but it's worth it, because not a single known acid acts on platinum. When heated, does not change its color and does not oxidize.

Types of non-ferrous metals

This group is the most in demand, as most materials are raw materials for the production of rolled metal. If we talk about the sphere of application, then it is quite extensive, it is: machine building, metallurgy, radio electronics, the sphere of high technologies, etc. According to physical properties, there are the following types of non-ferrous metals:

• Heavy (lead, zinc, tin, nickel, etc.);
• Light (aluminum, titanium, magnesium, etc.).

According to this classification, there is metallurgy of light and heavy metals. It's no secret that from this group you can make absolutely any technique. Please note that all types of metal alloys except iron are classified as colored. And now let's go further.

The main types of heavy metals

To date, there are approximately 40 definitions of the concept of this group of materials. Among the distinguishing features - an impressive atomic weight, usually more than 50. From this we can conclude that the list should include everything that goes after vanadium (regardless of density). But if we use a different definition, then the determining parameter may be the density, which should be more than that of iron (8 g / cm ³ ). In this case, the list will include: lead, mercury, copper, but tin will be behind the list. Today, the issue of environmental pollution of this group is extremely acute. This is due to the fact that many metals are used in heavy industry and fall into the ocean along with wastewater. The main problem is the high toxicity of mercury, lead, cadmium. In addition, some types of heavy metals have the feature of accumulating in living organisms. So, because of mercury poisoning in 1977 there were more than 2300 victims.

Mercury, lead and cadmium

These are the most dangerous non-ferrous metals related to heavy metals . Are the main polluters of the environment. Mercury is a highly toxic metal for a person, enters the ocean through the atmosphere and with sewage. When coal is burned at power plants, mercury compounds enter the atmosphere and then fall into the ocean as precipitation. In addition, many freshwater and marine inhabitants accumulate in their bodies a significant amount of mercury, which more than once led to human poisoning, and even death.

Cadmium is a dispersed and rather rare element that enters the ocean together with sewage from metallurgical and ore-dressing industries. It should be noted that cadmium is present in the human body, but it is very small. With chronic poisoning, bones are destroyed, and anemia begins. As for lead, this metal in the dispersed state is almost everywhere. Such types of metals, the photos of which we have quoted above, are excreted from the body, but slowly enough, so their excessive number causes serious health problems. Along with the continental dust, about 25 thousand tons of lead is taken into the ocean along with atmospheric precipitation.

On a note

As you can see, there are very different types and properties of metals. Something is not at all dangerous, and every day we carry a silver cross and a gold ring on our hand. Radioactive substances can kill a person, so environmentalists around the world are trying to partially solve the issue of the release of hazardous metals into the ocean and atmosphere. Of course, it is very difficult to solve such problems, especially considering that most entrepreneurs do not go into contact at all. Nevertheless, do not forget that without the conductors, which are also made of metal, electric circuits are impossible, and without iron there will be no cars and other things that are usual for us.

We did not mention a group of so-called radioactive metals of the Periodic Table of Mendeleyev. These include: technetium, polonium, promethium, etc. The main purpose is the 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 the form of ores and form various sulphides, carbonates and other chemical compounds. For the production of pure metals and their further use modern technological treatment and processing lines are used. Surely you will be interested to know that the human body also contains a small amount of metal compounds - about 3%. So, in the bones, we have calcium, iron is in the blood, magnesium is constantly accumulating in the muscles, and there is copper in the liver.

Well, here, in principle, and all that can be said about what kinds of metal alloys exist. Despite the fact that this is a rather complicated topic, it can be of interest to those who are fond of metallurgy.