What is composite material. Composite material Composite products

Today, builders are attracting great attention to composite panels. These advanced modern materials make it possible to create rare architectural style new building. Use composite panels for facades that have served long time. As a result of their use, the appearance buildings

They can be used in hot and cold regions due to their resistance to different temperatures. Cladding facades with such material leads to the creation of a favorable microclimate inside buildings and will also reduce air conditioning costs in summer time year and heating in winter.

What are the panels made of?

Aluminum composite panels are products that consist of two painted sheets of aluminum. The structure of this material is as follows:

• protective coating with anti-corrosion properties;
• a layer based on a primer;
• high strength aluminum sheet;
• fireproof mineral or polymer filler, it can be polyethylene, polyurethane, polypropylene, polystyrene;
• another layer of high-strength aluminum;
• primer;
• layer of varnish;
• protective film.

Each panel is coated with a special compound to provide greater strength. All layers are connected to each other using a special technology, thanks to which the product acquires high resistance to delamination. Depending on the purpose, in addition to paint, the product can be coated with an anti-rust varnish coating on both or one side, as a result of which the aluminum composite plate increases its wear resistance. Available finished products continuous tape. Having a lot of variety overall dimensions very convenient for consumers.

The composite panel is made by bending aluminum sheets.

It is desirable that the radius of curvature be as small as possible; if it is the same as the thickness of the plate, then the product meets all regulatory standards. During the production process, the material acquires precise planar characteristics, while the protective and surface paint layers are applied uniformly.

The surface of aluminum composite panels for facade can copy:

• wood;
• plaster;
• brick;
• natural stone.

On construction market There are aluminum composite panels with a noble metal effect, which becomes possible thanks to the electroplating method.

Properties of mounting profiles

All mounting profiles are divided into 3 types:

• open docking;
• joint with seal;
• using a moisture barrier.

To make a façade made of composite panels more rigid, they often use additional elements. The properties of this product are influenced by the filler that underlies the central layer. At the beginning of the production of such a product, manufacturers used polymer material as a filler - foamed polyethylene.

Aluminum composite has:

• light weight;
• good ductility;
• good noise insulation properties.

But this type has a main disadvantage, which is that polyethylene burns, supports the combustion process, melts and emits harmful smoke. Aluminum sheets with mineral filler. This foamed polyethylene contains a significant amount of fire retardants. Thanks to these mineral supplements, his physical properties. In this case, the filler ignites from an open flame, but if there is no source of fire, it goes out immediately, and it also:

• does not emit toxic smoke;
• doesn't flow.

Manufacturers from China and Europe produce technological innovations - fillers of A and A2 classes. Aluminum hydroxide is their basic component. These composite façade panels are classified as non-flammable. They can withstand 2-4 hours of open fire. However, this positive property makes it difficult to make finished products round or otherwise irregular shape. The thing is that they lack plasticity. Aluminum composite panels are expensive.

They are used on structures and buildings with the most stringent fire safety requirements.

Composite aluminum with a honeycomb structure is a separate class of products. In them between two metal sheets there is a network of thin aluminum jumpers of the drawings:

• cell phone;
• mesh;
• linear.

They differ:

• bending strength;
• light weight;
• expensive.

This type does not have sufficient ability to absorb noise and vibration. They are pressed through due to mechanical stress.

Main advantages

The composite material is available in various colors. Products come solid colors, as well as copying the texture of natural materials:

• wood;
• marble;
• granite

The front side lasts for a long time thanks to the applied paint coating. Other positive properties include simplicity different processes processing. For example, thanks to milling, technical holes can be made on the surface of aluminum façade panels. Ease of processing increases the scope of its use several times. The design of the material allows it to be converted into any shape, bent and cut.

The result is the ability to use for finishing non-standard buildings, which include domes, arches, and pyramids.

Ventilated façade made of composite aluminum panels has the ability to attenuate electromagnetic radiation. Other positive properties include the ability to protect walls from wind and dampness. A small weight cannot weigh down a building. When facing with a composite, the appearance of the walls will remain in their original state for a long time, because such a coating is resistant to weather and chemical influences. Due to the fact that the surface is smooth, dust and dirt do not accumulate on it. Curtain facade made of composite put on high rise buildings very beneficial because in this case the surface has the ability to self-clean.

Cladding with composite panels is carried out in short term. They will give the building a stylish, modern appearance and provide it with significant aesthetic properties.

Composite materials reduce heat loss, are safe from an environmental point of view and are not capable of storing electricity. They can withstand external influence for a long time. This material is very resistant to impact ultraviolet rays. The composite almost does not react in any way to aggressive environments.

Facade cladding of buildings harmful production This type of composite is recommended.

However, it must be borne in mind that the material also has disadvantages. So the product is not thermally insulating. It is necessary to take into account its low suitability for repair. If the cladding made of composite panels is damaged, it is quite difficult to repair. If it is necessary to replace the cassettes, those nearby will also need to be changed. With a low-quality composite material, the slab may delaminate, and then bubbles will form on the façade.

Areas of use of aluminum panels

Nowadays, ventilated facades made of composite panels are very popular. Exteriors of all kinds of structures are the most common area of ​​application. Composite facade consists of multilayer aluminum panels that are used for the external cladding of buildings.

A ventilated façade finished with a composite takes on a unique modern appearance. If you also have insulation, you can achieve significant savings electrical energy without incurring any additional costs to strengthen the foundation and load-bearing walls.

Installation of ventilated facades is simple due to the fact that it is possible to install panels on walls made of different material. At the same time, you do not need to prepare them in advance, which means you can save a lot cash. A lightweight, lightweight ventilated façade made of composite materials allows you to turn any designer’s idea into reality.

This material is often found in the interior space public institutions V:

• shopping centers;
• hospitals;
• clinics;
• airports;
• train stations;
• car showrooms;
• schools.

These are the places where you need durable material, capable of withstanding prolonged use in unchanged condition. In addition to ventilated facades, the composite is used in other places. It is often used in the restoration of buildings, the construction of unusual structures for outdoor advertising, and the construction of light temporary buildings. Often aluminum composite panels are involved in the construction of various decorative cornices, belts, external suspended ceilings, in column cladding.

Composite facades allow you to create a modern architectural style. And all this became possible thanks to low weight, ease of processing, increased flexibility and a variety of colors.

A composite site is special technology, presented by 1C-Bitrix. The purpose of using this technology is to speed up the website. A composite site loads several times faster than a regular site on 1C-Bitrix.

What is a composite site?

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Composite website: what is it and why is it needed?

A composite site is a special technology presented by 1C-Bitrix. The purpose of using this technology is to speed up the website. A composite site loads several times faster than a regular site on 1C-Bitrix.

What is a composite site?

How does a composite site work?

How to launch composite site technology?

Composite materials are materials consisting of two or more components that differ in nature or chemical composition, where the components are combined into a single monolithic structure with an interface between the components, the optimal combination of which allows to obtain a complex of physicochemical and mechanical properties, differing from the complex of properties of the components.

In a broad sense, the concept of “composite material” includes any material with a heterogeneous structure, i.e. structure consisting of two or more phases.

The first creator of composite materials was nature itself. Many natural structures (tree trunks, animal bones, human teeth, etc.) have a characteristic fibrous structure. It consists of a relatively plastic matrix substance and harder and more durable substances in the form of fibers. For example: wood is a composition consisting of bundles of high-strength cellulose fibers of a tubular structure, interconnected by a matrix of organic matter (lignin), which gives the wood lateral rigidity.

Examples of composite materials can be natural formations such as minerals. Jade – consists of closely packed needle-shaped crystals bound together at interfaces. This structure ensures the high viscosity of jade and therefore various tribes used it as a material for making axes.

general characteristics composite materials

And their classification

Attention to composite materials in Lately is continuously increasing. This is explained by the fact that the possibilities for increasing the mechanical properties of traditional structural materials have been largely exhausted.

Composite materials are significantly superior to all known structural alloys in terms of specific strength and rigidity, strength at high temperatures, resistance to fatigue failure and other properties. The level of a given set of properties is designed in advance and implemented during the manufacturing process of the material.

Rice. 20.1. Specific strength and rigidity of steel, titanium, aluminum alloys and composites (KAS-1, VKA-1B).

The properties of composite materials mainly depend on physical and mechanical properties components and the strength of the connection between them. Distinctive feature of these materials is that they demonstrate the advantages of the components, and not their disadvantages. At the same time, composite materials have properties that are not possessed by the individual components that make up them. To optimize the properties of the composition, components with sharply different but complementary properties are selected.

In terms of their composition, composite materials consist of a base (matrix) and a filler (strengthener, reinforcing component).

The basis (matrix) of composite materials are metals or alloys, polymers, carbon and ceramic materials.

The matrix binds the composition and gives it shape. The properties of the matrix largely depend technological modes obtaining composite materials and such important performance characteristics such as: operating temperature, fatigue resistance, density and specific strength.

Composite materials with combined matrices have been created, consisting of alternating layers (two or more) of different chemical composition. Such materials are called polymatrix. Polymatrix materials are characterized by a more extensive list beneficial properties. For example, using titanium as a matrix along with aluminum increases the strength of composite materials in the direction perpendicular to the axis of the fibers. Aluminum layers in the matrix help reduce the density of the material.

Another component called reinforcement or reinforcing component, or sometimes filler, is evenly distributed within the matrix. The concept of “reinforcing” means “introduced into a material in order to change properties,” but does not carry the unambiguous concept of “strengthening.”

Reinforcing components must have high strength, hardness, and elastic modulus. In these properties they are significantly superior to the matrix.

The properties of composite materials also depend on the shape or geometry, size, quantity and nature of the distribution of the filler (reinforcement pattern).

Based on their shape, fillers are divided into three main groups:

1. Zero-dimensional fillers, having very small sizes of the same order in three dimensions (particles);

2. One-dimensional fillers are small in two dimensions and significantly larger in size in the third dimension (fibers);

3. Two-dimensional fillers have two sizes commensurate with the size of the composite material and significantly exceed the third (plates, fabric).

The thread-like form of reinforcing elements has both positive and negative sides. Their advantage is high strength and the ability to create strengthening only in the direction in which it is structurally required. The disadvantage of this form is that the fibers are able to transfer load only in the direction of their axis, while there is no strengthening in the perpendicular direction, and in some cases even softening may occur.

Fillers used as reinforcement must have the following properties: high temperature melting, low density, high strength over the entire operating temperature range, processability, minimal solubility in the matrix, high chemical resistance, lack of toxicity during production and operation.

Composite materials that contain two or more different fillers are called polyreinforced.

If composite materials consist of three or more components, they are called hybrid.

Composite materials are classified according to several main characteristics:

a) material of the matrix and reinforcing components;

b) structure: geometry and arrangement of components;

c) method of obtaining;

d) areas of application.

Let's consider some classification characteristics of composite materials.

In the history of technology development, two important directions can be distinguished:

• development of tools, structures, mechanisms and machines,
• materials development.

It is difficult to say which of them is more important, because... they are quite closely interrelated, but without the development of materials, technical progress is impossible in principle. It is no coincidence that historians divide early civilization eras into the Stone Age, Bronze Age and Iron Age.

The current 21st century can already be attributed to the century of composite materials (composites).

The concept of composite materials was formed in the middle of the last, 20th century. However, composites are not a new phenomenon at all, but only a new term formulated by materials scientists for better understanding the genesis of modern structural materials.

Composite materials have been known for centuries. For example, in Babylon they used reeds to reinforce clay when building houses, and the ancient Egyptians added chopped straw to clay bricks. IN Ancient Greece Marble columns were strengthened with iron rods during the construction of palaces and temples. In 1555-1560, during the construction of St. Basil's Cathedral in Moscow, Russian architects Barma and Postnik used stone slabs reinforced with iron strips. The direct predecessors of modern composite materials can be called reinforced concrete and damask steel.

There are natural analogues of composite materials - wood, bones, shells, etc. Many types natural minerals are actually composites. They are not only durable, but also have excellent decorative properties.

Composite materials- multicomponent materials consisting of a plastic base - a matrix, and fillers that play strengthening and some other roles. There is a phase boundary between the phases (components) of the composite.

The combination of dissimilar substances leads to the creation of a new material, the properties of which differ significantly from the properties of each of its components. Those. a sign of a composite material is a noticeable mutual influence of the constituent elements of the composite, i.e. their new quality, effect.

By varying the composition of the matrix and filler, their ratio, using special additional reagents, etc., a wide range of materials with the required set of properties is obtained.

Great importance arrangement of composite material elements, both in directions effective loads, and in relation to each other, i.e. orderliness. High-strength composites, as a rule, have a highly ordered structure.

A simple example. A handful of sawdust thrown into a bucket cement mortar will not affect its properties in any way. If half of the solution is replaced with sawdust, the density of the material, its thermophysical constants, production costs and other indicators will change significantly. But a handful of polypropylene fibers will make concrete impact-resistant and wear-resistant, and half a bucket of fiber will provide it with elasticity, which is not at all characteristic of mineral materials.

Currently, in the field of composite materials (composites), it is customary to include a variety of artificial materials, developed and implemented in various branches of technology and industry, meeting general principles creation of composite materials

Why is interest in composite materials emerging right now? Because traditional materials no longer always or do not fully meet the needs of modern engineering practice.

Matrices in composite materials are metals, polymers, cements and ceramics. A wide variety of artificial and natural substances are used as fillers. various forms(large-sized, sheet, fibrous, dispersed, finely dispersed, microdispersed, nanoparticles).

Multicomponent composite materials are also known, including:

• polymatrix, when several matrices are combined in one composite material,
• hybrid, including several different fillers, each of which has its own role.

The filler, as a rule, determines the strength, rigidity and deformability of the composite, and the matrix ensures its solidity, stress transfer and resistance to various external influences.

A special place is occupied by decorative composite materials that have pronounced decorative properties.

Composite materials with special properties are being developed, for example, radio-transparent materials and radio-absorbing materials, materials for thermal protection of orbital spacecraft, materials with a low coefficient of linear thermal expansion and a high specific modulus of elasticity, and others.

Composite materials are used in all areas of science, technology, industry, incl. in residential, industrial and special construction, general and special mechanical engineering, metallurgy, chemical industry, energy, electronics, household appliances, clothing and footwear production, medicine, sports, arts, etc.

Structure of composite materials.

Based on their mechanical structure, composites are divided into several main classes: fibrous, layered, dispersion-strengthened, particle-strengthened and nanocomposites.

Fiber composites are reinforced with fibers or whiskers. Even a small filler content in composites of this type leads to a significant improvement in the mechanical properties of the material. The properties of the material can also be varied widely by changing the orientation of the size and concentration of the fibers.

In laminated composite materials, the matrix and filler are arranged in layers, such as in triplex, plywood, laminated wood structures and laminated plastics.

The microstructure of other classes of composite materials is characterized by the fact that the matrix is ​​filled with particles of a reinforcing substance, and they differ in particle sizes. In particle-strengthened composites, their size is greater than 1 micron, and the content is 20-25% (by volume), while dispersion-strengthened composites include from 1 to 15% (by volume) of particles ranging in size from 0.01 to 0.1 µm. The sizes of particles included in nanocomposites are even smaller and amount to 10-100 nm.

Some common composites

Concrete- the most common composite materials. Currently, a large range of concretes are produced, differing in composition and properties. Modern concretes are produced both on traditional cement matrices and on polymer ones (epoxy, polyester, phenol-formaldehyde, acrylic, etc.). Modern high-performance concretes are close to metals in strength. Decorative concrete is becoming popular.

Organoplasty- composites in which the fillers are organic, synthetic, and, less commonly, natural and artificial fibers in the form of tows, threads, fabrics, paper, etc. In thermosetting organoplastics, the matrix is ​​usually epoxy, polyester and phenolic resins, as well as polyimides. Organoplastics have a low density, they are lighter than glass and carbon plastics, and have relatively high tensile strength; high resistance to impact and dynamic loads, but at the same time, low compressive and bending strength. The most common organoplastics include wood composite materials. In terms of production volumes, organoplastics exceed steel, aluminum and plastics.

In foreign literature, new terms have recently become popular - biopolymers, bioplastics and, accordingly, biocomposites.

Wood composite materials. The most common wood composites include arbolites, xylolites, cement particle boards, laminated wooden structures, plywood and bent-glued parts, wood plastics, particle boards and fiberboards and beams, wood presses and press powders, thermoplastic wood-polymer composites.

Fiberglass- polymer composite materials reinforced with glass fibers, which are molded from molten inorganic glass. Both thermosetting synthetic resins (phenolic, epoxy, polyester, etc.) and thermoplastic polymers (polyamides, polyethylene, polystyrene, etc.) are most often used as a matrix. Fiberglass plastics have high strength, low thermal conductivity, high electrical insulating properties, and in addition, they are transparent to radio waves. Laminated material, in which fabric woven from glass fibers is used as a filler, is called fiberglass.

Carbon fiber reinforced plastics- carbon fibers serve as filler in these polymer composites. Carbon fibers are obtained from synthetic and natural fibers based on cellulose, acrylonitrile copolymers, petroleum and coal tar pitches, etc. The matrices in carbon plastics can be either thermosetting or thermoplastic polymers. The main advantages of carbon fiber reinforced plastics compared to fiberglass plastics are their low density and higher elastic modulus; carbon fiber reinforced plastics are very light and, at the same time, durable materials.

Based on carbon fibers and a carbon matrix, composite carbon-graphite materials are created - the most heat-resistant composite materials (carbon fiber plastics), capable of withstanding temperatures up to 3000 ° C for a long time in inert or reducing environments.

Boroplasty- composite materials containing boron fibers as a filler, embedded in a thermosetting polymer matrix, and the fibers can be either in the form of monofilaments or in the form of bundles braided with an auxiliary glass thread or tapes in which boron threads are intertwined with other threads. The use of boroplastics is limited high cost production of boron fibers, therefore they are used mainly in aviation and space technology in parts subjected to long-term loads in aggressive environments.

Press powders (press mixtures). More than 10,000 brands of filled polymers are known. Fillers are used both to reduce the cost of the material and to give it special properties. Filled polymer was first produced by Dr. Baekeland (Leo H. Baekeland, USA), who discovered it at the beginning of the 20th century. method for the synthesis of phenolformdehyde (bakelite) resin. This resin itself is a fragile substance with low strength. Baekeland discovered that adding fibers, particularly wood flour, to the resin before it hardened increased its strength. The material he created - bakelite - gained great popularity. The technology for its preparation is simple: a mixture of partially cured polymer and filler - press powder - under pressure irreversibly hardens in a mold. The first mass-produced product was produced using this technology in 1916, this was the gear shift knob of a Rolls-Royce car. Filled thermoset polymers are widely used in most different areas technology. A variety of fillers are used to fill thermosetting and thermoplastic polymers - wood flour, kaolin, chalk, talc, mica, carbon black, fiberglass, basalt fiber, etc.

Textolites- laminated plastics, fabric reinforced from various fibers. The technology for producing textolites was developed in the 1920s. based on phenol-formaldehyde resin. Fabric sheets are impregnated with resin, then pressed at elevated temperatures to produce textolite plates or shaped products. The binders in textolites are a wide range of thermosetting and thermoplastic polymers, and sometimes inorganic binders based on silicates and phosphates. Fabrics made from a wide variety of fibers are used as filler - cotton, synthetic, glass, carbon, asbestos, basalt, etc. Accordingly, the properties and applications of textolites are varied.

Composite materials with a metal matrix. When creating metal-based composites, aluminum, magnesium, nickel, copper, etc. are used as a matrix. The filler is high-strength fibers, refractory particles of various dispersion, thread-like single crystals of aluminum oxide, beryllium oxide, boron and silicon carbides, aluminum and silicon nitrides, etc. 0.3-15 mm long and 1-30 microns in diameter.

The main advantages of metal matrix composite materials compared to conventional (non-reinforced) metal are: increased strength, increased rigidity, increased wear resistance, increased creep resistance.

Composite materials based on ceramics. Reinforcement ceramic materials fibers, as well as metal and ceramic dispersed particles, makes it possible to obtain high-strength composites; however, the range of fibers suitable for reinforcing ceramics is limited by the properties source material. Metal fibers are often used. Tensile resistance increases slightly, but resistance to thermal shock increases - the material cracks less when heated, but there may be cases when the strength of the material decreases. This depends on the ratio of the thermal expansion coefficients of the matrix and filler.

Reinforcement of ceramics with dispersed metal particles leads to new materials (cermets) with increased durability, resistance to thermal shocks, and increased thermal conductivity. High-temperature cermets are used to make parts for gas turbines, fittings for electric furnaces, and parts for rocket and jet technology. Hard wear-resistant cermets are used to make cutting tools and details. In addition, cermets are used in special areas technologies are fuel elements nuclear reactors based on uranium oxide, friction materials for brake devices, etc.

A composite is a continuous inhomogeneous material that has been artificially created from several components with different physical and chemical properties. The mechanical characteristics of a composite material are determined by the ratio of the properties of the matrix and reinforcing elements, as well as the strength of their connection, which is ensured when making the right choice initial components and the method of their combination.

The most primitive composite material is bricks made of straw and clay, which were used by the ancient Egyptians.

Most often, a composite refers to materials based on resin or polymer matrices. Phenolic, epoxy, vinyl ester, polyester and polypropylene polymers are used to make composite materials. Reinforcing substances in the manufacture of composites are bulk substances and fibers. The strength of the material depends on the amount of resin - the less it is, the stronger it is. Today, to achieve ideal proportions of all components in a composite material, molding technology is constantly being improved.

Methods for molding composite materials

During the molding process, the matrix of the composite material is combined with its reinforcing substance, as a result of which a particular product can be manufactured. Thermosetting polymer matrices during the molding process pass through chemical reaction curing. Thermoplastic polymer matrices are melted and solidified in a given shape during the molding process. This process usually takes place in room temperature and normal pressure.

The most common composite today is cement with metal reinforcement or asphalt concrete.

There is also contact (manual) molding, which has a number of serious disadvantages. The product formed by this method contains an increased amount of resin, which makes it more fragile. In addition, it is difficult to achieve ideal proportions of the matrix and reinforcing substance, as well as maintain the thickness of the product, while avoiding internal air passages.

The vacuum molding process involves the use of an open tooling into which the composite components are placed and covered with a silicone membrane or polymer film. Then on equipment in conditions atmospheric pressure and elevated temperature, a vacuum is applied.