Have you ever wondered what the mysterious amorphous substances are? In structure, they differ from both solid and liquid. The fact is that such bodies are in a special condensed state, which has only short-range order. Examples of amorphous substances are resin, glass, amber, rubber, polyethylene, polyvinyl chloride (our favorite plastic windows), various polymers, and others. These are solids that do not have a crystal lattice. They also include sealing wax, various adhesives, ebonite and plastics.
Unusual properties of amorphous substances
During splitting, faces are not formed in amorphous bodies. The particles are completely random and are at a close distance to each other. They can be both very thick and viscous. How are they affected by external influences? Under the influence of various temperatures, bodies become fluid, like liquids, and at the same time quite elastic. In the case when the external impact does not last long, substances of an amorphous structure can break into pieces with a powerful blow. longoutside influence causes them to simply flow.
Try a little resin experiment at home. Lay it on a hard surface and you will notice that it begins to flow smoothly. That's right, it's an amorphous substance! The speed depends on the temperature indicators. If it is very high, then the resin will begin to spread noticeably faster.
What else is typical for such bodies? They can take any form. If amorphous substances in the form of small particles are placed in a vessel, for example, in a jug, then they will also take the form of a vessel. They are also isotropic, that is, they exhibit the same physical properties in all directions.
Melting and transition to other states. Metal and glass
The amorphous state of matter does not imply the maintenance of any particular temperature. At low rates, the bodies freeze, at high rates, they melt. By the way, the degree of viscosity of such substances also depends on this. Low temperatures contribute to reduced viscosity, high temperatures, on the contrary, increase it.
For substances of the amorphous type, one more feature can be distinguished - the transition to the crystalline state, and spontaneous. Why is this happening? The internal energy in a crystalline body is much less than in an amorphous one. We can see this in the example of glass products - over time, glasses become cloudy.
Metal glass - what is it? Metal can be removed from the crystal lattice induring melting, that is, to make a substance of an amorphous structure glassy. During solidification under artificial cooling, the crystal lattice is formed again. Amorphous metal has simply amazing resistance to corrosion. For example, a car body made from it would not need various coatings, since it would not be subjected to spontaneous destruction. An amorphous substance is a body whose atomic structure has unprecedented strength, which means that an amorphous metal could be used in absolutely any industrial sector.
Crystal structure of substances
To be well versed in the characteristics of metals and be able to work with them, you need to have knowledge about the crystal structure of certain substances. The production of metal products and the field of metallurgy would not have been able to get such a development if people did not have certain knowledge about changes in the structure of alloys, technological methods and operational characteristics.
The four states of matter
It is well known that there are four states of aggregation: solid, liquid, gaseous, plasma. Solid amorphous substances can also be crystalline. With such a structure, spatial periodicity in the arrangement of particles can be observed. These particles in crystals can perform periodic motion. In all the bodies that we observe in a gaseous or liquid state, one can notice the movement of particles in the form of a chaotic disorder. Amorphous solids (such as metals incondensed state: ebonite, glass products, resins) can be called frozen-type liquids, because when they change shape, you can notice such a characteristic feature as viscosity.
The difference between amorphous bodies from gases and liquids
Manifestations of plasticity, elasticity, hardening during deformation are characteristic of many bodies. Crystalline and amorphous substances have these characteristics to a greater extent, while liquids and gases do not. But on the other hand, you can see that they contribute to an elastic change in volume.
Crystalline and amorphous substances. Mechanical and physical properties
What are crystalline and amorphous substances? As mentioned above, amorphous can be called those bodies that have a huge viscosity coefficient, and at ordinary temperature their fluidity is impossible. But the high temperature, on the contrary, allows them to be fluid, like a liquid.
Crystal-type substances seem to be completely different. These solids can have their own melting point depending on the external pressure. Getting crystals is possible if the liquid is cooled. If you do not take certain measures, then you can notice that various centers of crystallization begin to appear in the liquid state. In the area surrounding these centers, the formation of a solid occurs. Very small crystals begin to combine with each other in a random order, and a so-called polycrystal is obtained. Such a body isisotropic.
Characteristics of substances
What determines the physical and mechanical characteristics of bodies? Atomic bonds are important, as is the type of crystal structure. Ionic crystals are characterized by ionic bonds, which means a smooth transition from one atom to another. In this case, the formation of positively and negatively charged particles. We can observe the ionic bond in a simple example - such characteristics are characteristic of various oxides and s alts. Another feature of ionic crystals is the low conductivity of heat, but its performance can increase markedly when heated. At the nodes of the crystal lattice, you can see various molecules that are distinguished by strong atomic bonds.
Many minerals that we find everywhere in nature have a crystalline structure. And the amorphous state of matter is also nature in its purest form. Only in this case the body is something formless, but the crystals can take the form of the most beautiful polyhedra with flat faces, as well as form new solid bodies of amazing beauty and purity.
What are crystals? Amorphous-crystalline structure
The shape of such bodies is constant for a certain connection. For example, beryl always looks like a hexagonal prism. Do a little experiment. Take a small crystal of cubic s alt (ball) and put it in a special solution as saturated as possible with the same s alt. Over time, you will notice that this body has remained unchanged - it has again acquiredthe shape of a cube or a ball, which is inherent in s alt crystals.
Amorphous-crystalline substances are such bodies that can contain both amorphous and crystalline phases. What influences the properties of materials of such a structure? Mainly different ratio of volumes and different arrangement in relation to each other. Common examples of such substances are materials from ceramics, porcelain, glass-ceramic. From the table of properties of materials with an amorphous-crystalline structure, it becomes known that porcelain contains the maximum percentage of glass phase. The figures fluctuate between 40-60 percent. We will see the lowest content in the example of stone casting - less than 5 percent. At the same time, ceramic tiles will have higher water absorption.
As you know, such industrial materials as porcelain, ceramic tiles, stone casting and glass-ceramics are amorphous-crystalline substances, because they contain glassy phases and at the same time crystals in their composition. At the same time, it should be noted that the properties of materials do not depend on the content of glass phases in it.
Amorphous metals
The use of amorphous substances is most actively carried out in the field of medicine. For example, rapidly cooled metal is actively used in surgery. Thanks to the developments associated with it, many people have been able to move independently after severe injuries. The thing is that the substance of an amorphous structure is an excellent biomaterial for implantation in bones. Receivedspecial screws, plates, pins, pins are introduced in case of severe fractures. Previously, steel and titanium were used for such purposes in surgery. Only later it was noticed that amorphous substances decompose very slowly in the body, and this amazing property makes it possible for bone tissues to recover. Subsequently, the substance is replaced by bone.
Use of amorphous substances in metrology and precision mechanics
Exact mechanics is based precisely on accuracy, and therefore it is called so. A particularly important role in this industry, as well as in metrology, is played by ultra-precise indicators of measuring instruments; this can be achieved by using amorphous bodies in devices. Thanks to accurate measurements, laboratory and scientific research is carried out at institutes in the field of mechanics and physics, new drugs are obtained, and scientific knowledge is improved.
Polymers
Another example of the use of an amorphous substance is polymers. They can slowly change from a solid to a liquid, while crystalline polymers are characterized by a melting point, not a softening point. What is the physical state of amorphous polymers? If you give these substances a low temperature, you can see that they will be in a glassy state and exhibit the properties of solids. Gradual heating causes the polymers to begin to move into a state of increased elasticity.
Amorphous substances, examples of which we have just given, are intensively used inindustry. The superelastic state allows polymers to be deformed in any way, and this state is achieved due to the increased flexibility of links and molecules. A further increase in temperature leads to the fact that the polymer acquires even more elastic properties. It begins to pass into a special fluid and viscous state.
If you leave the situation uncontrolled and do not prevent a further increase in temperature, the polymer will undergo degradation, that is, destruction. The viscous state shows that all units of the macromolecule are very mobile. When a polymer molecule flows, the links not only straighten out, but also come very close to each other. Intermolecular action turns the polymer into a hard substance (rubber). This process is called mechanical glass transition. The resulting substance is used to produce films and fibers.
Polyamides, polyacrylonitriles can be obtained from polymers. To make a polymer film, you need to force the polymers through dies that have a slotted hole and apply them to the tape. In this way, packaging materials and bases for magnetic tapes are produced. Polymers also include various varnishes (forming foam in an organic solvent), adhesives and other bonding materials, composites (polymer base with filler), plastics.
Polymer applications
This kind of amorphous substances are firmly rooted in our lives. They are applied everywhere. These include:
1. Various bases formanufacture of varnishes, glues, plastic products (phenol-formaldehyde resins).
2. Elastomers or synthetic rubbers.
3. The electrical insulating material is polyvinyl chloride, or the well-known plastic PVC windows. It is resistant to fires, as it is considered slow-burning, has increased mechanical strength and electrical insulating properties.
4. Polyamide is a substance with very high strength and wear resistance. It has high dielectric characteristics.
5. Plexiglas, or polymethyl methacrylate. We can use it in the field of electrical engineering or use it as a material for structures.
6. Fluoroplast, or polytetrafluoroethylene, is a well-known dielectric that does not exhibit the properties of dissolution in solvents of organic origin. Its wide temperature range and good dielectric properties allow it to be used as a hydrophobic or anti-friction material.
7. Polystyrene. This material is not affected by acids. It, like fluoroplastic and polyamide, can be considered a dielectric. Very durable with regard to mechanical impact. Polystyrene is used everywhere. For example, it has proven itself well as a structural and electrical insulating material. It is used in electrical and radio engineering.
8. Probably the most famous polymer for us is polyethylene. The material exhibits resistance when exposed to aggressive environments, it absolutely does not allow moisture to pass through. If the packaging is made of polyethylene, you can not be afraid that the contents will deteriorate under the influence of strongrain. Polyethylene is also a dielectric. Its application is extensive. Pipe structures, various electrical products, insulating film, sheaths for cables of telephone and power lines, parts for radio and other equipment are made from it.
9. PVC is a high polymer material. It is synthetic and thermoplastic. It has a structure of molecules that are asymmetrical. Almost does not pass water and is made by pressing with stamping and by molding. Polyvinyl chloride is used most often in the electrical industry. On its basis, various heat-insulating hoses and hoses for chemical protection, battery banks, insulating sleeves and gaskets, wires and cables are created. PVC is also an excellent replacement for harmful lead. It cannot be used as a high-frequency circuit in the form of a dielectric. And all due to the fact that in this case the dielectric losses will be high. Highly conductive.
