Despite the fact that more and more industrial and domestic use artificial materials, to renounce the use of metals is not yet possible.They possess a unique combination of properties and alloys allow maximum use of their potential.In what areas is received and the use of metal?
features a group of elements under the metal
understand the totality of inorganic chemicals with characteristic properties.They usually include the following:
- high thermal conductivity;
- flexibility, relative ease of machining;
- a relatively high melting point;
- good electrical conductivity;
- typical "metallic" luster;
- role in the reactions of the reducing agent;
- high density.
course, not all elements of this group have all these properties, for example, mercury, a liquid at room temperature, gallium melts from the heat of human hands, and bismuth is hardly plastic.But in general, all these features can be traced in aggregate metals.
internal classification
metals conventionally divided into several categories, each of which brings together elements that are closest to each other by different parameters.There are the following groups:
- alkaline - 6;
- alkaline - 4;
- transition - 38;
- light - 7;
- semimetals - 7;
- lanthanides - 14 + 1;
- actinides - 14 + 1
outside the group is still two: the beryllium and magnesium.Thus, at the moment of all the open elements 94 scientists refer to metals.
In addition, it is worth mentioning that there are other classification.According to them, separately considered precious, platinum group metals, post-transition, refractory metals, ferrous and non-ferrous, and so on. D. Such an approach makes sense only under certain order, so that it is more convenient to use a standard classification.
history of producing
mankind throughout its development was closely linked to the processing and use of metals.Besides the fact that they were the most abundant elements, one could produce a variety of articles by machining.As the skills of ore was not yet, at first it was only the use of nuggets.At first it was a soft metal, which gave the name of the Copper Age, who replaced the stone.During this period, it developed a method for cold forging.Some civilizations made possible smelting.Gradually, people have mastered the receipt of non-ferrous metals such as gold, silver, tin.
later replaced by copper came the Bronze Age.It lasted about 20 thousand years and was a turning point for humanity, because in this period it became possible to produce alloys.There is a gradual development of the industry, improved methods of producing metals.However, in the 13-12 centuries.BC.e.there was the so-called Bronze collapse that marked the beginning of the Iron Age.It allegedly happened because of depletion of tin.A lead and mercury, open at this time, could not be a substitute for bronze.So people had to develop the production of metals from ores.
next period lasted a relatively short time - less than the Millennium, but left a bright trace in the history.While iron has been known much earlier, it is hardly used because of their disadvantages compared with bronze.In addition, the last was much easier to get, while the smelting of the ore was more time-consuming task.The fact is that the native iron is quite rare, so it is not surprising that the rejection of bronze is so slow.
skill in metal recovery
By analogy with how the human ancestor made the first tool, a sharp rock tied to a stick, the transition to the new material turned out to be equally grandiose.The main advantages of metal products consisted in the fact that they are easier to make, and it was possible to repair.Stone does not have the same ductility and malleability, so any instrument from it can only be done over again, it was impossible to repair them.
Thus, it is the transition to the use of metals has led to a further improvement of the instruments of labor, the emergence of new household items, jewelry, produce that was previously impossible.All this has given a boost to technical progress, and laid the foundation for the development of metallurgy.
Modern methods
If in ancient times people were familiar only to obtain metals from ores, or they could settle for nuggets, at the present time there are other ways.They were made possible by the development of chemistry.Thus, there are two main areas:
- Pyrometallurgy.She began her early development and is associated with the high temperatures necessary for the processing of the material.Modern technology in this area allow the use of plasma.
- Hydrometallurgy.This direction is engaged removing elements from the ore, waste concentrates and m. G. With water and chemicals.For example, a very common method involves obtaining metals by electrolysis, it is also quite popular method of cementation.
There is another interesting technology.Production of precious metals of high purity and with minimal losses was made possible thanks to her.We are talking about refining of.This process - a type of refinement, that is a gradual separation of impurities.For example, if gold is used melt saturation chlorine and platinum dissolved in mineral acids, followed by separation reagents.
way, the production of metals by electrolysis is most often used when smelting or recovery uneconomical.This is the case with aluminum and sodium.There are also more innovative technology enables the production of non-ferrous metals even from a fairly low-grade ores without significant cost, but we will go about it a little later.
About alloys
Most of the metals known in antiquity did not always meet some needs.Corrosion insufficient hardness, brittleness, fragility, impermanence - every element in its pure form has its drawbacks.Therefore, it became necessary to find new materials that combine the advantages of a well-known, that is to find ways to produce metal alloys.Today, there are two basic methods:
- casting.Mixed components melt cools and crystallizes.It is this method yielded the first examples of alloys bronze and brass.
- pressing.The powder mixture was subjected to high pressure, and then sintered.
Further improvement
In recent decades, the most promising seems to be getting metal biotechnology, primarily by bacteria.It has become possible to extract from sulphidic raw material of copper, nickel, zinc, gold, and uranium.Researchers hoped connect microorganisms to processes such as leaching, oxidation, adsorption and precipitation.In addition, it is extremely urgent is the problem of deep cleaning of wastewater, for her, too, trying to find a solution that involves the participation of bacteria.
Application
Without metals and alloys would be impossible life in the form in which it is now known to mankind.High-rise buildings, aircraft, dishes, mirrors, electrical appliances, automobiles, and many other creatures only because of the long journey of people from stone to copper, bronze and iron.
Due to their exceptional electrical and thermal conductivity metal used in wires and cables for various applications.Gold is used to make a non-oxidizing contacts.Due to its strength and hardness metals commonly used in construction and for the most different constructions.Another area of application - tool.To manufacture a working example of the cutting part frequently used hard alloys and special steels.Finally, the precious metals are highly prized as a material for jewelry.So applications abound.
Interesting about metals and alloys
use of these elements is so wide and has a long history, which is not surprising emergence of various funny situations.They are simply a couple of interesting facts and should lead finally:
- Prior to widespread aluminum greatly appreciated.Cutlery, upon receipt of the guests enjoyed the Napoleon III, had made it out of this material and were the pride of the monarch.
- name platinum in Spanish means "serebrishko."Such an unflattering name of the item is received due to the relatively high melting point and, therefore, it is impossible for a long time to use it.
- Pure gold is soft and it can be easily scratched with a fingernail.That is why for the manufacture of jewelry it is alloyed with silver or copper.
- There alloys with a curious property of thermoelasticity, that is the effect of "memory" shape.When deformation and subsequent heating they are returned to the original state.
