Have you ever wondered what 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, hard rubber and plastics.
Extraordinary properties of amorphous substances
During splitting, no faces are formed in amorphous bodies. Particles are completely random and are at a close distance to each other. They can be either very thick or viscous. How do external influences affect them? Under the influence of various temperatures, the bodies become fluid, like liquids, and at the same time quite elastic. In the case when the external action does not last long, the substances of the amorphous structure can crack into pieces with a powerful blow. Long-term influence from the outside leads to the fact that they simply flow.
Try a small resin experiment at home. Put it on a hard surface and you will notice that it begins to flow smoothly. That's right, it's an amorphous substance! Speed ββdepends on temperature. If it is very high, the resin will begin to spread much faster.
What else is characteristic of 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 a substance does not imply the maintenance of any particular temperature. At low rates, the bodies freeze; at high levels, they melt. By the way, the degree of viscosity of such substances also depends on this. Low temperature contributes to lower viscosity, high, on the contrary, increases it.
For substances of the amorphous type, one more feature can be distinguished - the transition to a crystalline state, moreover, spontaneous. Why is this happening? The internal energy in a crystalline body is much less than in an amorphous one. We can notice this on the example of glass products - over time, the glass becomes cloudy.
Metal glass - what is it? The metal can be removed from the crystal lattice during melting, that is, to make the substance of the amorphous structure glassy. During solidification by artificial cooling, the crystal lattice forms again. Amorphous metal has simply amazing resistance to corrosion. For example, a car body made of 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 industry.
The crystalline structure of substances
In order to well understand the characteristics of metals and be able to work with them, you need to have knowledge about the crystalline structure of certain substances. The production of metal products and the metallurgy industry would not have been able to receive such development if people did not have certain knowledge about changes in the structure of alloys, technological methods, and operational characteristics.
Four states of matter
It is well known that there are four states of aggregation: solid, liquid, gaseous, and plasma. Amorphous solids can also be crystalline. With this 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 (for example, metals in a condensed state: ebonite, glass products, resins) can be called frozen 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 to a greater extent possess these characteristics, while liquids and gases do not have such properties. But then 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 high temperature, on the contrary, allows them to be fluid, like a liquid.
Substances of a crystalline type seem to be completely different. These solids can have their melting point, depending on external pressure. Obtaining crystals is possible if the liquid is cooled. If you do not take certain measures, you can see that in the liquid state various crystallization centers begin to appear. In the area surrounding these centers, the formation of solids. Very small crystals begin to combine with each other in random order, and the so-called polycrystal is obtained. Such a body is isotropic.
Characteristics of substances
What determines the physical and mechanical characteristics of bodies? Atomic bonds are important, as well as the type of crystal structure. Ion type 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 with a simple example - such characteristics are inherent in various oxides and salts. Another feature of ionic crystals is their low heat conductivity, but its performance can noticeably increase with heating. At the nodes of the crystal lattice, one can notice various molecules that differ in strong atomic bonds.
Many minerals that we find everywhere in nature have a crystalline structure. And the amorphous state of matter is also pure nature. Only in this case, the body is something shapeless, but crystals can take the form of beautiful polyhedra with flat faces, and also form new bodies of amazing beauty and purity.
What are crystals? Amorphous-crystalline structure
The shape of such bodies is constant for a particular connection. For example, beryl always looks like a hexagonal prism. Do a little experiment. Take a small crystalline cubic table salt (bowl) and put it in a special solution as saturated as possible with the same table salt. Over time, you will notice that this body has remained unchanged - it again took the form of a cube or ball, which is inherent in the crystals of sodium chloride.
Amorphous-crystalline substances are bodies that can contain both amorphous and crystalline phases. What affects the properties of materials of such a structure? Mostly different volume ratios and different locations in relation to each other. Common examples of such substances are materials from ceramics, porcelain, 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. Indicators range from 40-60 percent. We will see the lowest content on the example of stone casting - less than 5 percent. At the same time, ceramic tiles will have a higher water absorption.
As you know, such industrial materials as porcelain, ceramic tiles, stone casting and ceramic are amorphous-crystalline substances, because they contain vitreous phases and at the same time crystals in their composition. 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 chilled metal is actively used in surgery. Thanks to the developments associated with it, many people were able to move independently after severe injuries. The thing is that the substance of the amorphous structure is an excellent biomaterial for implantation in the bone. The obtained special screws, plates, pins, pins are inserted in case of severe fractures. Earlier in surgery, steel and titanium were used for such purposes. Only later it was noticed that amorphous substances decompose very slowly in the body, and this amazing property makes it possible to restore bone tissue. Subsequently, the substance is replaced by bone.
The use of amorphous substances in metrology and precision mechanics
Precision mechanics is based precisely on accuracy, and therefore it is called that. A particularly important role in this industry, as well as in metrology, is played by ultra-precise indicators of measuring instruments, which can be achieved by using amorphous bodies in devices. Thanks to accurate measurements, laboratory and scientific studies are 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 amorphous substances is polymers. They can slowly transition from a solid state to a liquid, while crystalline polymers are characterized by a melting point rather than a softening point. What is the physical state of amorphous polymers? If you provide these substances with a low temperature, you will notice that they will be in a glassy state and exhibit the properties of solids. Gradual heating helps the polymers begin to transition into a state of increased elasticity.
Amorphous substances, examples of which we have just cited, are intensively used in industry. The superelastic state allows the polymers to deform as they like, but this state is achieved due to the increased flexibility of the units and molecules. A further increase in temperature leads to the fact that the polymer acquires even more elastic properties. He begins to transition into a special fluid and viscous state.
If you leave the situation unchecked and do not prevent a further increase in temperature, the polymer will undergo destruction, that is, destruction. A viscous state indicates that all macromolecule units are very mobile. When the polymer molecule flows, the units not only straighten out, but also come very close to each other. Intermolecular exposure turns the polymer into a hard substance (rubber). Such a process is called mechanical glass transition. The resulting substance is used for the production of films and fibers.
Based on polymers, polyamides, polyacrylonitriles can be obtained. To make a polymer film, you need to push the polymers through the dies, which have a slit-like hole, and apply to the tape. In this way, packaging materials and tape bases are made. Polymers also include various varnishes (forming foam in an organic solvent), adhesives and other bonding materials, composites (polymer base with filler), and plastics.
Polymer Applications
Amorphous substances of this kind have firmly taken root in our lives. They are used everywhere. These include:
1. Various bases for the manufacture of varnishes, adhesives, plastic products (phenol-formaldehyde resins).
2. Elastomers or synthetic rubbers.
3. Electrical insulation material - polyvinyl chloride, or well-known plastic PVC windows. It is resistant to fires, as it is considered to be slow-burning, has increased mechanical strength and electrical insulation properties.
4. Polyamide - a substance with a very high strength, resistance to wear. It is characterized by high dielectric characteristics.
5. Plexiglass, 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 known dielectric that does not exhibit dissolution properties in solvents of organic origin. A wide temperature range and good dielectric properties allow it to be used as a hydrophobic or antifriction material.
7. Polystyrene. This material is not affected by acids. He, like fluoroplastic and polyamide, can be considered an insulator. Very durable with regard to mechanical stress. Polystyrene is used everywhere. For example, he is well established 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 is stable when exposed to aggressive environments, it absolutely does not let moisture through. If the packaging is made of polyethylene, you can not be afraid that the contents will deteriorate under the influence of heavy rain. Polyethylene is also a dielectric. Its application is extensive. Pipe constructions, various electrical products, insulation film, sheaths for telephone and power line cables, parts for radio and other equipment are made from it.
9. Polyvinyl chloride is a highly polymer substance. It is synthetic and thermoplastic. It has the structure of molecules that are asymmetrical. Almost does not let water through and is made by pressing by 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. Polyvinyl chloride is also an excellent substitute for harmful lead. It cannot be used as high-frequency circuits in the form of a dielectric. And all due to the fact that in this case, the dielectric loss indicators will be high. It has high conductivity.