A huge part of the extracted metals is used in industry in the form of alloys. They learned how to make even before our era. What are alloys? What is the name of the alloy, the basis of which is copper and zinc? Where is it applied? The answers to these questions are in the article.
What are alloys?
Alloys are materials made from a mixture of several metals and other elements. They may contain random impurities of natural components. One of the first known alloys was bronze. People created products from it as early as the 4th millennium BC.
Alloys are made to improve the quality of metals. For example, to make gold jewelry last longer, be stronger or have a certain shade, a small amount of nickel, platinum, zinc or silver is added to it.
By mixing several components, you can change the properties of the metal, increase the melting point and ductility, give strength and hardness, and increase wear resistance. The most common alloys are bronze, brass (an alloy of copper and zinc), cast iron, steel, babbit, win, duralumin.
They are used in mechanical engineering, construction, industry, aircraft engineering, etc. Magnets are made from a mixture of nickel, magnesium and cobalt. Tin and lead were previously used to make cutlery, while cast iron was widely used to make household items such as pans or irons.
Copper zinc alloy
A mixture of copper and zinc is called brass. Like bronze, it appeared before our era. Since then, the technology of its manufacture has changed somewhat. Previously, to make brass, copper was mixed with charcoal and zinc ore. In the 18th century, the Englishman James Emerson proposed mixing the metals themselves without the use of ore.
The basis of brass is copper. The zinc content varies from 5 to 45 percent. Because of the yellowish color, reminiscent of gold, in ancient Rome brass was called orichalcum, which literally means "golden copper".
An alloy of copper and zinc is not always limited to these metals. It may contain some tin, lead, iron, manganese, nickel and other components. If you add more tin than zinc, you get a completely different material - tin bronze.
brass properties
Depending on the amount of zinc, the color and quality of brass vary. The smaller it is, the more red and saturated the color of the material. If an alloy of copper and zinc does not contain other elements, it is called simple brass, which is divided into two types: tompak (zinc up to 20%) and yellow brass (zinc from 20%).
The material brass is very ductile and exhibits greater resistance to corrosion than copper. The melting point ranges from 880 o C to 950 o C, with large proportions of zinc it decreases. The metal lends itself perfectly to welding, rolling and pressure treatment.
In humid air, yellow brass cracks. This can be corrected by annealing at a temperature of 250 ° C. Multi-component brass resists corrosion better and is stronger. The addition of tin contributes to the resistance to sea water.
The content of impurities in the alloy can be found on the product label. Capital letters indicate the name of the components. First comes the letters "L", then the remaining additional ones. After them, in accordance with the letter order, the percentage of substances is indicated, with the first two digits indicating the amount of copper in the alloy. So, marking LAZH60-1-1 means that brass consists of 60% copper, 1% aluminum and 1% iron, the rest is zinc.
Where is brass used?
Brass has good heat capacity. It is no coincidence that in Ancient Russia samovars were made from it. In Rome, under Octavian Augustus, sestertia and dupondia coins were minted from brass. In the Middle Ages, it was used for making jewelry, framing compasses, decorating art objects.
And now the material is used everywhere. Brass is used to make jewelry and small interior items. A special technique of artificial aging gives a special charm. Figurines, door handles, mirror frames are cast from it.
The high technological properties of brass make it possible to use the material for the production of small building parts, tubes, plates, strips and wires. An alloy with lead is used for cars and watches, tompak is used for steel cladding and the manufacture of radiator pipes. Insignias are made from a composition with an aluminum content of 0.5%, since it has a golden hue.
Copper alloys with a zinc content up to which are called brass have practical applications.
Rice. 417. Inclusions in rolled copper
The state diagram is shown in fig. 418. Complicated at first glance, the diagram is actually composed of five simple peritectic diagrams.
In alloys of copper and zinc in the solid state, the formation of six phases is possible. Let's consider them. a-solid solution of zinc in copper: the solubility of zinc in copper at room temperature is equal, it does not practically change to and decreases to
A solid solution based on a compound with an electronic bond type has a simple cubic body-centered lattice. The ordered arrangement of atoms is preserved only at temperatures no higher. At higher temperatures, the atoms of copper and zinc in a body-centered lattice are arranged statistically. An ordered solid solution is denoted by a solution based on an electronic type compound and has a complex cubic lattice. The ordering temperature of this phase is
A solid solution based on an electronic type compound with a hexagonal close-packed lattice.
Solid solution; the nature of the chemical compound underlying this solid solution has not been established.
Solid solution of copper in zinc.
At room temperature, brasses that are practically used either consist of only -crystals (Fig. 419), or are a mixture of a- and -crystals (Fig. 419, b).
The mechanical properties of the alloys depending on the zinc content are shown in fig. 420. Zinc increases the strength and ductility of the alloy. The alloy with the highest ductility
The transition through the boundary of a single-phase region ( sharply reduces plasticity; -brass has maximum strength at a relatively low plasticity for brass -brass is very brittle. Due to
(click to view scan)
noted circumstances (small ductility) not only for and but also -brass have no practical application. Brasses are used having the structure a or
The casting properties of brasses are determined by the mutual arrangement of the liquidus and solidus lines. Since the liquidus and solidus lines for crystallization of the a- and -phases lie close to one another, the casting properties of brasses are characterized by a low tendency to segregation, good fluidity, a tendency to form a concentrated shrinkage cavity and, consequently, high shrinkage.
Brass is easily plastically deformable (especially a-brass) and therefore brass is made into rolled semi-finished products (sheets, strips, profiles, etc.).
Rice. 420. Mechanical properties of alloys
The behavior of various brasses during hot working is peculiar. A-brasses that are ductile at room temperature turn out to be in the range less plastic than -brass. Although the strength of a-brass at room temperature is lower than that of -brass; at temperatures above P-brass are less strong and more ductile. For this reason, brasses with such a zinc content (more than 32-39%) are most suitable for hot rolling, so that at high temperature the structure would consist of or P-crystals (see Fig. 418). On the contrary, for the production of thin sheets and wire (i.e., for cold deformation), it is advisable to use brasses that have maximum ductility at room temperature (i.e., single-phase a-brasses with a zinc content of about
Brass contamination with bismuth and lead has a harmful effect on the ability to deformation in a hot state. The reason should be sought in the formation of low-melting inclusions of these metals along the grain boundaries. However, lead has a harmful effect only on a-brass, which does not experience phase transformations. When the zinc content is more than lead, located along the grain boundaries, as a result of recrystallization, a 0 is inside the grains and does not interfere with pressure treatment. Therefore, lead contamination in brasses with a content of lead can be tolerated to a much greater extent, and when the content is higher, lead is introduced deliberately until such brasses are processed by pressure in a single-phase P state and lead does not prevent the brass from plastically deforming. At the same time, separate inclusions of lead increase the machinability of the cutting tool, which facilitates chip breaking.
Brass is marked with the letter L, followed by a number indicating the average copper content in the alloy. Since zinc is cheaper than copper, the more zinc in brass, the cheaper it is.
Practically used brasses, depending on the structure at room temperature, are divided into two categories: a-brass and a-brass; a-brasses contain copper not less than the brand of these brasses, etc. They are made in the form of thin sheets, strips and other semi-finished products, from which they are stamped
various details. a-Brass with a higher copper content have a gold color and are used for jewelry and decorative items. Such brasses containing a high percentage of copper are called tombac.
Brass contain ; the most common brand of brass of this brand is made of bars, and various parts are made from them using cutting.
The mechanical strength of brass is low. For -brasses are characteristic the following values mechanical properties: -brasses have somewhat greater strength but less ductility
A multicomponent or double alloy of copper and zinc, as many people know, is called brass. Zinc plays a key role in this alloy. In addition, it contains additives of iron, lead, nickel, manganese and other elements.
1 What is an alloy of zinc and copper, what is it called?
Brass, which will be discussed in this article, is characterized by excellent resistance to corrosion and a high strength index. This distinguishes it from many other metals, as well as directly from copper. Under atmospheric conditions, brass has an average corrosion resistance value between copper and zinc.
The described alloys are famous for their unique technological characteristics, which allows them to be used for the manufacture of all kinds of easily molded and machined products with relatively small geometric dimensions.
Any brass is ideal for the production of castings (this is due to the slight tendency of the alloy to segregation and its excellent fluidity). Also, from brass of different grades, wonderful semi-finished products of a rolled type are obtained - wire, strips, sheets, various profile products, tapes. The production process of such semi-finished products is very simple, since alloys based on zinc and copper can easily be deformed, which is called plastic.
Brass can contain zinc from 5 to 45 percent (there are alloys with a high content of this chemical element, but they are used extremely rarely in human practice). In those cases where the concentration of zinc in the alloy is from 20 to 36 percent, brass is called yellow, 5-20 percent - red (otherwise - tompak).
Its value is higher than that of brass (the situation is similar with the electrical conductivity index). In addition, copper is more expensive than brass. It is clear that it is more economically feasible to use alloys rather than pure copper materials, since they practically do not differ from each other in a number of technological, mechanical and antifriction characteristics.
2 Two-component and multi-component brass
The division of the alloys of interest to us into red (tompac) and yellow is not the only way to classify them. Brass, in addition, is divided into two- and multi-component. Two-component ones include copper (there is always more of it) and zinc, as well as very few other inclusions. Tompak is a bright representative of such compositions. In it, zinc is always no more than 10 percent, and the concentration of copper can reach 97 percent (minimum - 88).
Brass with two components changes its properties depending on what phase composition it has. There are single- and two-phase alloys. The former have a structure when a solution of (solid) zinc is present in copper. AT this case brass exhibit a high degree of ductility. But two-phase combinations, in which zinc contains more than 39 percent, are described by insufficient plasticity, but at the same time they are much more durable.
Single-phase alloys are easily processed by pressure. Due to the plasticity of brass, their shape can be changed not only at high, but also at low temperatures. At the same time, there is one nuance. It lies in the fact that at temperatures from 300 to 700 degrees tompak or other brass (one- or two-phase) it is forbidden to deform, since in this interval there is a zone of brittleness in the alloy.
Multicomponent compositions (as a rule, they are called special) include a number of other alloying components in addition to zinc and copper. Usually multi-component brass contains the following elements:
- nickel - it is introduced to increase the corrosion resistance of alloys and their strength characteristics;
- tin - an alloying component that increases the resistance of brass products to rusting in salt water (for example, in the sea) and their strength;
- silicon - an element that increases the antifriction capabilities of a zinc-copper alloy, but at the same time worsens their strength and hardness;
- lead - its addition to brass makes it easy to process with cutting tools, but, unfortunately, there is a decrease in the mechanical capabilities of the alloy;
- manganese - alloying brass with manganese provides high corrosion resistance of the composition and excellent strength (the effect of introducing this element becomes more noticeable if tin, aluminum and iron are introduced into the alloy together with manganese).
As you can see, different components affect the properties of the composition of copper and zinc differently, whether it be tompac or another alloy, due to which it is possible to create alloys with special characteristics.
3 How is brass marked?
It is not difficult to understand the marking of the described alloys. In simple (two-component) brasses, the letter "L" is in the first place of their brand, and then comes a two-digit number. This number indicates how much copper is contained in the alloy (data are given as a percentage). Thus, if we see the marking L70 in front of us, it immediately becomes clear that this composition contains 70% copper and 30% zinc.
Multicomponent alloys have slightly more complex markings. After the letter "L", which tells the consumer that it is brass, and not any other composition, other letters are placed in front of him. Under them are encrypted alloying additives introduced into the alloy. And after these "letter ciphers" there are numbers (they are separated from each other by hyphens):
- the first (two-digit) determines the content of copper in the alloy;
- the rest talk about the amount of alloying components.
For example, let's look at the brass LAZhMts66-6-3-2. It contains 66% copper (the first number after the letters), 6% aluminum (the second number), 3% iron (the third number) and 2% manganese (the fourth number). Adding these numbers together, we get the sum 77. This means that the second main component in this alloy (zinc) contains 23% (subtract 77 from 100).
We add that casting brass, which we will discuss below, are marked differently. In them, after the letter indicating the alloying component, they immediately put a number that determines the percentage of this very component in the alloy. That is, the composition of the alloy, for example, LTS40Mts1.5, is deciphered as follows:
- zinc - 40%;
- manganese - 1.5%;
- the rest is copper.
4 Wrought and casting brasses
Wrought alloys (tompac and others) are characterized by high anti-friction characteristics, high anti-corrosion resistance and ductility. In addition, they are very easily and reliably connected to steel by welding. For this reason, they are used to produce various bimetallic structures and products. And directly tompak, which has a noble golden hue, is used for the production of all kinds of fittings and artistic elements (its soldering, as well as other copper products, is quite simple).
Deformable brass grades are used for manufacturing:
- condenser pipes (LMsh68-0.05, LO60-1, LO62-1, LO70-1, LO90-1, LA77-2);
- rustproof elements of machines (LK80-3), river and sea vessels(LMtsA57-3-1, LAZH60-1-1);
- products made by cutting (LZhS58-1-1);
- bushings, bolts, nuts (LS59-1, LMts58-2, LS60-1);
- matrices for printing plants (LS64-2).
Double brass (not tompak) is used for the production of machine parts and nozzles with large wall thicknesses (L60), forged parts (L68), components of chemical and heat engineering units (L80, L90) and other products.
Cast grade brass due to its properties (high fluidity, excellent technological and mechanical performance, corrosion resistance, lack of tendency to segregation) is recommended to be used for the manufacture of the following parts:
- fittings of automobile hydraulic mechanisms (LTs25S2);
- bearings, separators (LC40S);
- worm screws with a large mass (LTs23A6ZhZMts2);
- critical products operating at temperatures in the region of +300 degrees (LC40MtsZZH);
- rust-resistant products (LCZOAZ).
A word of 6 letters, the first letter is "T", the second letter is "O", the third letter is "M", the fourth letter is "P", the fifth letter is "A", the sixth letter is "K", the word for the letter "T", the last "K". If you do not know a word from a crossword puzzle or a crossword puzzle, then our site will help you find the most difficult and unfamiliar words.
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- cheap copper-zinc alloy, mainly for watches, watch chains, jewelry characteristic of poor dapper people
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- Copper-zinc alloy, brass grade
- an alloy called yellow copper
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Alloy of zinc and copper, 6 letters, 6 letter "b", crossword puzzle
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Alloy of copper and zinc, 6 letters, crossword puzzle
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