The rebellion effect by friction. External and internal Rebinder Effects

Rebinder effect

Let us continue the story of cracks living in a crystal. The first thorough report on his opening Peter Alexandrovich Rebelder made late in the summer of 1928 on a steamer, descending down the Volga - from Nizhny Novgorod to Saratov. Delegates sailed on the ship

VI All-Russian Congress of Physicists and guests of the Congress. Among the guests were the largest physics of the time: Max Born, Peter Deba, Charles Darwin, Paul Dirac and many others. For the history of Soviet physics, it was a significant congress, because it was during this congress that the three largest achievements of young Soviet physics were reported and discussed: the effect of a rummary of light (L. I. Mandelstam reported), the first results obtained in the study of chain reactions (N. N. Semenov reported about them), and the effect of adsorption reduction of strength (it was reported by P. A. Rebelder).

P. A. Rebider report called a skeptical attitude. The speaker argued that the mechanical properties of the crystalline body can be substantially changed if there is specially selected substances on its surface. The speaker told about the experiments confirming his point of view. All this looked more than strange, because whatever the substance was located on the surface, only the "surface" crystal atoms are aware of its existence, and their disappearing little is aware. The relative proportion of surface atoms from the number of wire-forming radius turns out to be equal

? = 2?RA/?R. 2 \u003d 2A / R. ,

where but - interatomic distance. If a R \u003d. 10 -1 cm, but = 3 . 10 -8 cm,

that ? ? 10 -7, i.e. on the surface of such a wire there is one ten millionth share of all atoms, of which it consists. They cannot determine the strength of a massive sample, for it because atoms in volume are obviously responsible. Remember: such considerations arose and due to the effect of Ioffe.

Years passed, new facts, guesses, theoretical assessments appeared. It turned out that the speaker was right. Extensive experience of conferences and seminars indicate that the speakers are usually right. Not always, but most often. They about the subject of the report thought more and more interested than their opponent listeners.

So - the effect of the Rebinder: Crystal, the surface of which is coated with the so-called surfactant, detects mechanical properties that significantly differ from the properties of the same crystal, the surface of which is clean. For example, a significantly reduced tensile strength can be significantly reduced, the crystal can detect increased fragility.

Very impressive classic experience, which P. A. Rebelder loved to demonstrate during lectures. Experience simple. Initially, you should make sure that the thin zinc plate under the influence of small efforts is easily bent, it turns out to be plastic. Then it is necessary to clean the surface of the surface of the crystal and apply a drop of mercury. After this procedure, the crystal bending is accompanied by the appearance of a crack. It actively penetrates mercury, and the crack is rapidly developing. Mercury, located on the surface of a plastic zinc, made it fragile. I have repeatedly seen this lecture demonstration performed by Peter Alexandrovich. Demonstrating, he was always happily excited, and in his hawk there was something from a schoolboy's habits, surprising friends with a spectacular focus.

This large, rooted gray people were characterized by childhood. When there were parts of the fragile destroyed plate of zinc in his hands, he looked victorious of the listeners and said: "No hand agility!"

The processes associated with the manifestation of the rebatera effect in the form, which was observed in the experiment described, are not very simple. They depend on physical properties and crystal, and substances listed on its surface.

We will try to understand the physics of the effect, meaning crystal BUT , on the surface of which there is some surfactant IN. May turn out (and this turns out to be in a huge amount of combinations BUT and IN ) that atoms are variety IN profitably accommodate between the atoms of the variety A. split between them. This process can be helped by attaching stretching efforts to crystal, and thus weaken the connection BUT -BUT . If the introduction of atoms of the variety IN in crystal BUT it happened, in it appear links BUT -IN . But the connection A-B. may be significantly weaker than connections A-A. , And it can determine the reduced strength of the crystal.

To the told you need to add the following. The main events associated with destruction, as a rule, occur at the mouth of a developing crack, to which atoms of the coating should have time from the coating layer. IN . They can be supplied either the diffusion process along the surface, or the process of spreading the substance IN On the surface of the crack, developing in a crystal BUT .

With any mechanism, these deliveries should occur fairly quickly so that the mouth of the cracks in the atoms of the varieties in, seeking to be implemented in the crystal L. It appropriately to pay attention to the fact that the effect of the rebinder is characterized by many features and effects of fun, and the effect of Griffiths. They are related to the features of the crack development process under the action of stresses.

And here is another experience illustrating other manifestation of the rebellion effect. A slightly molten gallium is poured into a high glass glass and a thin polycrystalline zinc plate is placed on its bottom. Then the glass is filled with a special solution that cleans the zinc surface. Next happens next. Gallium begins to crawl over zinc surface. This can be clearly clearly, since a moving matte track is formed on the zinc. The zinc plate covered with gallium, begins to settle on the bottom of the glass, folding in the harmonica or twisting into the roll. Spontaneously, only under the action of its own weight!

Gallium, penetrating into the boundaries between the grains of the zinc polycrystalline plate, weakens them, and the grains get the opportunity to easily move away. This is what we see, watching how soft zinc plate is settled in a glass with gallium.

In the first experiment, anomalous fragility, in second-abnormal plasticity. An examples of a sharp decrease in the hardness of crystals of rocks and metals could be given, the acquisition of the ability to easily turn into powder and many other examples of changes in the mechanical properties of crystalline bodies under the influence of surfactants.

The reader, not even very prone to fantasy, will easily imagine the enormous role that the rebellion effect plays in nature and in many technological processes. I will help the reader: in the presence of surfactants it is easier to handle the cutter, it is easier to stamp, make it easier to drill rocks, it is easier to escape crystal in powder ...

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Rebinder Effect

The effect of adsorption decrease in the strength of solid bodies, facilitating the deformation and destruction of solid bodies due to the reversible physicochemical effects of the medium. P. A. Reobener OM (1928) is open when studying the mechanical properties of calcite crystals and stone salt. It is possible when the solid body is inhibited, which is in a strained state, with a liquid (or gas) adsorption-active medium. P, E. It is very universal - observed in solid metals, ionic, covalent and molecular mono- and polycrystalline bodies, glasses and polymers, partly crystallized and amorphous, porous and solid. The main condition for the manifestation of R. E. - related nature of contacting phases (solid body and medium) for chemical composition and structure. Form and degree of manifestation of R. e. depend on the intensity of interatomic (intermolecular) interactions of contacting phases, the values \u200b\u200band type of stresses (tensile voltages are necessary), the rate of deformation, temperature. A significant role is played by the real body structure - the presence of dislocations, cracks, extraneous inclusions, and others. The characteristic form of manifestation of R. e. - multiple drop in strength, increasing the fragility of a solid body, a decrease in its durability. So, the zinc plate moistened with mercury under load will not be twisted, but the fragile is destroyed. Another form of manifestation of R. E. - plasticizing environment for solid materials, such as water on plaster, organic surfactants (see surfactants) to metals, etc. Thermodynamic R. E. Determined by a decrease in the formation of a new surface during deformation as a result of a decrease in free surface energy (see surface energy) of a solid body under the influence of the environment. Molecular nature R. E. It consists in facilitating the break and restructuring of intermolecular (interatomic, ionic) bonds in a solid body in the presence of adsorption-active and at the same time, sufficiently movable foreign molecules (atoms, ions). The most important areas of Technical Annex R. E. - relief and improving the mechanical processing of various (especially high-sided and hard-working) materials, regulation of friction and wear processes using lubricants (see Lubricant), efficient preparation of crushed (powdered) materials, obtaining solid bodies and materials with a given dispersed structure (see. Dispersed structure) and the required combination of mechanical and other properties by disagrement and subsequent seal without internal stresses (see also physico-chemical mechanics). The adsorption and active medium can also apply significant harm, for example, reducing the strength and durability of machine parts and materials under operating conditions. Elimination of factors contributing to the manifestation of R. e. In these cases, it allows to protect materials from unwanted effects of the medium.

LIT: Goryunov Yu. V., Pertsov N. V., Sums B. D., Rebinder Effect, M., 1966; Reobener P. A., Schukin E. D., Surface phenomena in solids in the processes of their deformation and destruction, "the successes of physical sciences", 1972, t. 108, in. 1, p. 3.

L. A. Shits.

Great Soviet Encyclopedia. - M.: Soviet Encyclopedia. 1969-1978 .

Watch what is "Rebinder Effect" in other dictionaries:

Lowering the strength of solid bodies in adsorption active media (solutions of surface active substance, electrolytes, salting melts, etc.). Opened P. A. Rebelder in 1928. Used to improve dispersion efficiency, grinding, ... ... Big Encyclopedic Dictionary

- (adsorption reduction of strength) Reduction of surface (interfacial) energy due to physical. or chemical. processes on the surface of solid bodies, leading to a change in its mechanism. properties (reduction of strength, fragility, decrease ... ... Physical encyclopedia

Lowering the strength of solid bodies in adsorption-active media (solutions of surfactants, electrolytes, salting melts, etc.). Opened P. A. Rebelder in 1928. Used to improve the efficiency of dispersing, grinding, material processing with cutting and ... encyclopedic Dictionary

Restoretra effect (adsorption reduction of strength), changing the mechanical properties of solid bodies due to physicochemical processes, causing a decrease in surface (interfacial) body energy. Manifests itself in reducing the strength and ... ... Wikipedia

See Physico Chemical Mechanics ... Chemical encyclopedia

Lowering TV strength. bodies in adsorption-active media (PAH surfactants, electrolytes, salting melts, etc.). Open P. A. Rebelder in 1928. Used to improve the efficiency of dispersion, grinding, material processing with cutting and ... ... Natural science. encyclopedic Dictionary

hall Effect - The occurrence of the transverse electric field and the potential difference in the metal or semiconductor, through which the electric current passes, when placing it in a magnetic field, perpendicular to the current direction. Opened American ... ...

effect of Mesbauer - resonant absorption of γ quanta atomic nuclei, observed when the source and absorber γ radiation solid, and the energy of quanta is small (150 keV). Sometimes the effect of M. is called resonance, absorption without recoil or nuclear ... Encyclopedic dictionary for metallurgy

seebecki effect - the phenomenon of the occurrence of the electromotive force in the electrical circuit, consisting of different conductors, the contacts between which have different temperatures; Opened in 1821 by German physicist T. Seebek. Electrical power, ... ... Encyclopedic dictionary for metallurgy

effect Bausinger - reduction of metal resistance or alloy with small plastic deformations (for example, with compression) after preliminary deformation of the opposite sign (with tension). Monocrystals of pure metals The effect of Baushinger ... ... Encyclopedic dictionary for metallurgy

Books

The role of surface phenomena in the structural and mechanical behavior of solid polymers, A. L. Volynsky, N. F. Bakeev. The book outlines modern ideas about the role of surface phenomena in the structural and mechanical behavior of amorphous and crystalline polymers. The processes of development and healing are considered ...

In addition to the action of chemical processes that affect the properties of the surface and friction interaction between solid bodies, there is an open and studied P.A. The rebel is a similar lubricant, due to purely molecular interaction of lubricant with solid surfaces, obtained the name "Rebinder Effect".

Real solids have both superficial and internal structure defects. As a rule, such defects have redundant free energy. Due to the physical adsorption of surface-active substances (surfactant) molecules (surfactant) there is a decrease in the level of free surface energy of the solid in the places of landing. This reduces the operation of the output of dislocations to the surface. Surfactants penetrate the cracks and in the intercrystalline space, having a mechanical impact on their walls and, spreading them, lead to a fragile cracking of the material and reduce the strength of contacting tel. And if such processes are developing only on the protractions of contacting bodies, reducing the resistance to the shift of the irregularities of this material, in general, this process leads to the surface to smooth the surface, reduce the specific pressure in the contact zone and in general

reducing friction and wear of rubbing tel. But if normal loading under friction increases significantly, high specific pressure apply to the entire contour area, the softering of the material is carried out on a large section of the surface and leads to a very rapid destruction.

The Rebinder Effect is widely used as in the development of lubricants (for this, special surfactants are introduced into the lubricant) and to facilitate the deformation and processing of the material in the manufacture of machine parts (for this, special lubricants and emulsions are used in the form of coolant lubricants).

The manifestation of the rebellion effect occurs on a wide variety of materials. These are metals, rocks, glass, machine elements and equipment. The medium causing a decrease in strength can be gaseous and liquid. Often molten metals can act as a surfactant. For example, copper released when moltening the sliding bearing becomes surfactant for steel. Penetrating into the cracks and the intercrystalline space of the carriage axes, this process causes fragile destruction of the axes and the cause of traffic accidents.

Without paying due attention to the nature of the process, we often began to face examples when ammonia causes cracking of brass parts, gaseous combustion products sharply accelerate the process of destruction of turbine blades, melted magnesium chloride acts destroyably on high-strength stainless steel and a number of others. The knowledge of the nature of these phenomena opens up opportunities to escape the issues of increasing the wear resistance and the destruction of responsible parts and assemblies of machinery and equipment, and with the proper use of the rebinder effect, improve the productivity of the processing equipment and the efficiency of the use of friction pairs, i.e. to save energy.

Effect of sliding speed and roughness surfaces on boundary friction

Effect of temperature and normal burden on boundary friction

In the adsorption of superficial substances, the free energy of the solid is reduced. At the same time, the resistance of the surface layer of the solid is decreased by plastic deformation, the plastic flow rate is facilitated and the output of the dislocations to the surface. The top layer of the metal can have a smaller microhardness than the underlying, saturated layers, as well as lower yield strength and hardening coefficient. The surface layer of metal deforming in the presence of surfactant has a smaller grain structure. This phenomenon of adsorption plasticization of solids is called external Rebinder Effect. The effect is implemented, for example, when stretching the wire through a smaller diameter, in the presence of surfactants. Under these conditions, a thinner surface layer is involved in the deformation and the pull force is significantly lower. The thickness of the plasticized layer is approximately 0.1 μm. Unlike chemical modification, the peculiarity of the rebinder effect is that it is manifested with the joint action of the medium (surfactant) and mechanical stresses, and also in the removal of the surfactant, the phenomenon of plasticizing the surface layer disappears.

The internal effect of the Rebinder (adsorption-defined) It is realized in the adsorption of molecules on the surfaces of cracks, which occur in the surface layer of the friction body. When the active centers of molecules reach a region, the size of which is less than two sizes of molecules, the last, pulling the walls of the crack and experiencing the pressure of neighboring molecules, strive to separate it. At the same time, the pressure on the walls at the vertex of the crack can reach 10 MPa and initiate its development. This phenomenon contributes to the destruction of the surface layer. It is manifested in the process of cutting metals in the presence of Pav contained in the composition of the coolant. The precipulating effect of adsorbed molecules prevents the crack closure after removing the load under the condition, if the interaction forces in its vertex is insufficient to displace the molecules of the adsorption and boundary layers. In this case, the resistance of the material is reduced fatigue destruction.

Rebember Peter Aleksandrovich (03.x.1898-12.vii.1972), Soviet Physico-Chemist, Academician of the USSR Academy of Sciences since 1946 (Corresponding Member since 1933), was born in St. Petersburg. He graduated from the Physics and Mathematics Faculty of Moscow University (1924). In 1922-1932 He worked at the Institute of Physics and Biophysics of the Academy of Sciences of the USSR and at the same time (in 1923-1941) - in the Moscow State Pedagogical Institute. K.Libknecht (from 1923 - Professor), from 1935 - Head of the Department of Dispersed Systems in the Colloid-Electrochemical Institute (from 1945 - Institute of Physical Chemistry) of the USSR Academy of Sciences, since 1942 - Head of the Department of Colloid Chemistry in Moscow University.

The work of the Rebinder is devoted to physicochemia dispersed systems and surface phenomena. In 1928, the scientist discovered the phenomenon of lowering the strength of solid bodies due to the reversible physicochemical effect on them the medium (rebeider effect) and in the 1930-1940s. He developed ways to facilitate the processing of very solid and difficult materials.

He discovered the electrocapillary effect of plasticizing metal single crystals during creep during the polarization of their surface in electrolyte solutions, investigated the features of aqueous solutions of surfactants, the effect of adsorption layers on the properties of dispersed systems, revealed (1935-1940) the main patterns of education and stabilization of foam and emulsions, as well as the phase treatment process in emulsions.

The scientist found that the detergent action includes a complex complex of colloid-chemical processes. Rebelder studied the processes of education and the structure of micelles of surfactants, developed the ideas about the thermodynamic stable micelle soap with a lyophobic inner core in a lyophilic medium. The scientist chose and substantiated the optimal parameters for the characteristics of the rheological properties of dispersed systems and proposed the methods of their definition.

In 1956, the scientist discovered the phenomenon of adsorption decrease in the strength of metals under the action of metal melts. In the 1950s. The scientist has created a new area of \u200b\u200bscience - physico-chemical mechanics. As Reobener himself wrote: "The final problem of physicochemical mechanics is to develop a scientific basis for obtaining solids and systems with specified structure and mechanical properties. Consequently, the task of this area includes the creation of an optimally directed technology of production and processing on the merits of all building and structural materials of modern equipment - concrete, metals and alloys, especially heat-resistant, ceramics and metal ceramics, rubber, plastics, lubricants. "

Since 1958, Rebelder - Chairman of the Scientific Council of the USSR Academy of Sciences on the problems of physicochemical mechanics and colloidal chemistry, then (since 1967), Chairman of the USSR National Committee at the International Committee for Surfactants. From 1968 to 1972, he was the editor-in-chief of the "colloid magazine." The scientist was awarded by two orders of Lenin, had the title Hero of Socialist Labor (1968), the Winner of the USSR State Prize (1942).

Restoretra effect, the effect of adsorption reduction of solid bodies, facilitating the deformation and destruction of solid bodies due to the reversible physicochemical effects of the medium. P. A. Rebinder (1928) is open when studying the mechanical properties of calcite crystals and a stone salt. It is possible when the solid body is inhibited, which is in a strained state, with a liquid (or gas) adsorption-active medium. The rebellion effect is very universal - observed in solid metals, ionic, covalent and molecular mono- and polycrystalline bodies, glasses and polymers, partially crystallized and amorphous, porous and solid. The main condition for manifestation of the rebellion effect is the related nature of the contacting phases (solid body and medium) for the chemical composition and structure. The form and degree of manifestation of the effect depends on the intensity of interatomic (intermolecular) interactions of contacting phases, the values \u200b\u200band type of stresses (tensile voltages are necessary), the rate of deformation, temperature. A significant role is played by the real structure of the body - the presence of dislocations, cracks, extraneous inclusions, etc. The characteristic form of manifestation of the rebellion effect is a multiple drop in strength, increasing the fragility of a solid body, a decrease in its durability. So, the zinc plate moistened with mercury under load will not be twisted, but the fragile is destroyed. Another form of manifestation is the plasticizing effect of the environment on solid materials, such as water on plaster, organic surfactants for metals, etc. The thermodynamic effect of the Rebinder is due to a decrease in the formation of a new surface during deformation as a result of a decrease in the free surface energy of the solid body under the influence of the environment . The molecular nature of the effect consists in facilitating the gap and restructuring of intermolecular (interatomic, ionic) bonds in a solid body in the presence of adsorption-active and at the same time there are enough movable foreign molecules (atoms, ions).

The most important areas of technical applications are to relieve and improve the mechanical processing of various (especially high-end and hard and hard) materials, regulation of friction and wear processes using lubricants, effective production of crushed (powdered) materials, obtaining solid bodies and materials with a given dispersed structure and a desired combination of mechanical mechanical and other properties by deaging and subsequent seal without internal stresses. The adsorption and active medium can also apply significant harm, for example, reducing the strength and durability of machine parts and materials under operating conditions. Elimination of factors that contribute to the manifestation of the rebellion effect in these cases allows us to protect materials from unwanted environmental impact.

Even the most durable bodies have a huge number of defects, which weaken their load resistance make less durable compared to what predicts the theory. In the mechanical destruction of the solid body, the process begins with the place where microdefects are located. The increase in the load leads to development at the site of the defect of the microcrack. However, the removal of the load leads to the restoration of the initial structure: the width of the microcrack is often insufficient to complete overcoming the forces of intermolecular (interatomic) interaction. Reducing the load leads to "tightening" of microcracks, the forces of intermolecular interaction are restored almost completely, the crack disappears. The fact is that the formation of crack is the formation of a new solid surface, and such a process requires energy costs equal to the energy of the surface tension, multiplied to the area of \u200b\u200bthis surface. Reducing the load leads to "tightening" cracks, since the system is committed to reducing the energy in it stored. Therefore, for the successful destruction of the solid body, it is necessary to cover the resulting surface with a special substance called superficially active, which will reduce work to overcome molecular forces in the formation of a new surface. Surfactants penetrate into microcracks, cover their surface with a layer of thickness in just one molecule (which determines the possibility of using very small amounts of additives of these substances), preventing the process of "collapses", preventing the resumption of molecular interaction.

Surfactants in certain conditions facilitate the grinding of solids. Very thin (up to the size of colloidal particles) Grinding solids is generally impossible to be carried out without adding surfactants.

Now it remains to remember that the destruction of the solid (i.e., the formation of new microcracks) begins precisely from the place where the defect of the structure of this body is located. In addition, the added surface-active substance is adsorbed mainly also in the locations of defects - thus facilitates its adsorption on the walls of future microcracks. We give the words of Academician of the Rebinder: "The separation of the part occurs precisely on these weak points [location of defects], and, therefore, the small particles formed during grinding can no longer contain these most dangerous defects. Expressing more precisely, the probability of meeting a dangerous weak place becomes the smaller than its size.

If, shredding the real solid body of any nature, we reach the particles, the dimensions of which are approximately the same as the distances between the most dangerous defects, then such particles are almost certainly not to contain hazardous defects of the structure, they will become much stronger than large samples of the same Body itself. Consequently, it is necessary only to crush the solid body to sufficiently small pieces, and these pieces of the same nature, the same composition will be the most durable, almost perfectly durable.

Then these homogeneous, doctorate particles must be connected, make a solid (high-strength) body of the desired size and shape, make the particles are tightly packed and very firmly merge with each other. The detail of the machine or the construction item thus obtained should be much stronger than the starting material before grinding. Naturally, not so durable as a separate particle, since new defects will arise in the commodity places. However, when used by the process of combining particles, the strength of the starting material will be exceeded. This requires particularly tightly packing fine particles so that the forces of intermolecular interaction occurred between them. Usually for this use compression of particles with pressing and heating. Heated by pressing a fine-grained unit, without bringing it to melting. With increasing temperature, the amplitude of thermal oscillations of molecules (atoms) in the crystal lattice increases. At the points of contact, the oscillating molecules of two adjacent particles come closer and even mixed. The clutch forces increase, the particles are tightened, practically not leaving emptiness and pores, the defects of the contacts of contact disappear.

In some cases, the particles can be glued or soldered with each other. In this case, the process must be kept in this mode so that the layers of glue or solder do not contain defects.

The indigenous improvement of the chopping process, based on the practical application of the rebellion effect, turned out to be very useful for many industries. Technological processes of grinding significantly accelerated, while energy consumption significantly decreased. A subtle grinding made it possible to carry out many technological processes at less high temperatures and pressures. As a result, more high-quality materials were obtained: concrete, ceramic and metal-ceramic products, dyes, pencil masses, pigments, fillers, and much more. It is facilitated by the mechanical processing of refractory and heat-resistant steels.

Here's how it describes how it describes the method of applying the rebender effect. adding a surfactant. The mixture is diluted with limit vibration in the process of applying to glued surfaces as a fine layer. After rapid solidification, the glue layer becomes the most durable place in the design. "

The use of the ideas of the Rebinder Academician relative to the facilitation of the chopping process of solid bodies is of great practical importance, for example, to develop a method for reducing the strength of minerals in order to increase the efficiency of drilling in solid rocks.

Lowering the strength of metals under the action of metal melts.In 1956, the Reobener discovered the phenomenon of lowering the strength of metals under the action of metal melts. It was shown that the greatest decrease in the surface energy of the solid (metal) almost to zero can be caused by molten media, which are close to a solid body in molecular nature. Thus, the tensile strength of zinc single crystals was reduced to dozen times when applied to the surface of a layer of liquid metal tin thickness in 1 micron and less. Such effects for refractory and heat-resistant alloys are observed under the action of liquid low-melting metals.

The open phenomenon was very important for improving the methods of processing metals by pressure. This process is not possible without the use of lubrication. For materials of new techniques - refractory and heat-resistant alloys - the treatment is especially facilitated by the use of active lubricants, which soften the thin surface layers of the metal (which, in fact, occurs under the action of small amounts of metallic melts). At the same time, the metal seems to lubricate itself - the harmful excess deformation arising during processing, which causes the so-called slope - preventing the processing processing increased strength. New possibilities of processing metals with pressure at normal and elevated temperatures are open: the quality of the products increases, the depreciation of the processing tool decreases, the energy consumption for processing.

Instead of the transfer of expensive metal into the chips in the process of manufacturing a product with cutting, a plastic change in shape can be applied: pressure treatment without metal loss. In this case, the quality of products is also rising.

A sharp decrease in the strength of the surface layer of metals plays a significant role in improving the operation of friction assemblies. There is an automatically operating mechanism of wear management: if there are random irregularities on rubbing surfaces (burstages, scratches, etc.), in places of their dislocation develop high local pressure, causing surface flow of metals, significantly lightweight under the action of adsorbed melts (moistened with melted surface layer Metal loses strength). Drinking surfaces are easily sent or highlighted. The introduced "lubricant" causes an accelerated "wear" of irregularities, the speed of work (running) of machines increases.

Active impurity melters can be used as crystallization process modifiers. Adsorbing on crystalline-embryos of the allocated metal, they reduce the speed of their growth. Thus, a fine-grained metal structure with higher strength is formed.

The process of "training" of metal in the surfactant medium has been developed. Metal is subjected to periodic surface effects that do not lead to destruction. Due to facilitating plastic deformations in the surface layers, the metal in the internal volume is "warm up", the crystal grain grille is dispected. If such a process is carried out at a temperature close to the temperature of the start of recrystallization of the metal, the formation of a small-crystalline structure with a much higher hardness occurs in the surfactant medium. And the grinding of metals in the preparation of a thin powder does not cost without the use of surfactant melts. In the future, from this powder receives products with hot pressing (in full accordance with the hardening process described above).

Restorera effect in polymers. Outstanding Soviet Physico-Chemist Academician Peter Alexandrovich Rebinder was the first to try to affect the work of the destruction of the solid. It was the rebelder that it was possible to understand how this could be done. Back in the 20s of the last century, it used for this purpose so-called surfactant, or adsorption-active, substances that are able to effectively adsorb on the surface even at low concentration in the environment and sharply reduce the surface tension of solids. Molecules of these substances attack intermolecular bonds at the top of the growing crack crack and, adsorbing on freshly educated surfaces, weaken them. Picking up special fluids and entering them on the surface of the destroyed solid body, the rebinder achieved a striking decrease in the work of tensile destruction (Fig. 1). The figure shows the deformation and strength curves of zinc monocrystal (piling of the thickness of order of a millimeter) in the absence and in the presence of surfactant fluid. The moment of destruction in both cases is marked by arrows. It is clearly seen that if just stretching the sample, it is destroyed with more than 600% elongation. But if the same procedure is done by applying liquid tin on its surface, the destruction occurs in just a ~ 10% elongation. Since the work of destruction is the area under the dependence curve of the voltage of deformation, it is not difficult to note that the presence of fluid reduces the work not even at times, but to orders. It was this effect that was called the effect of a refisrer, or an ad-sorption decrease in solid strength.

Fig.1. The dependence of the voltage from the deformation of zinc single crystals at 400 ° C: 1 - in air; 2 - in the melt of tin

The effect of the Rebinder is a universal phenomenon, it is observed in the destruction of any solid bodies, including polymers. Nevertheless, the nature of the object contributes to the process of destruction, and the polymers in this sense are no exception. Polymer films consist of large whole molecules held together by Van der Wales or hydrogen bonds, which are noticeably weaker than covalent ties within the molecules themselves. Therefore, the molecule, even being a member of the team, retains some isolated and individual qualities. The main feature of polymers is the chain structure of their macromolecules, which ensures their flexibility. Flexibility of molecules, i.e. Their ability to change its form (due to the deformation of valence angles and turns of the links) under the action of external mechanical stress and a number of other factors underlies all the characteristic properties of polymers. First of all, the abilities of macromolecules to mutual orientation. True, it is necessary to make a reservation that the latter applies only to linear polymers. There is a huge amount of substances having a large molecular weight (for example, proteins and other biological objects), but not possessing the specific qualities of polymers, since strong intramolecular interactions interfere with their macromolecules bend. Moreover, a typical representative of polymers - natural rubber, - being "sewn" with the help of special substances (the process of vulcanization), can turn into a solid - an ebony that does not supply any signs of polymeric properties at all.

In the polymers, the rebellion effect manifests itself very peculiar. In the adsorption-active fluid, the emergence and development of the new surface is observed not only during destruction, but significantly earlier in the process of deformation of the polymer, which is accompanied by the orientation of the macromolecule.

Fig.2. The appearance of polyethylene terephthalate samples, stretched in air (a) and in the ad-sorption-active medium (n-propanole) (b).

rebinder Polymer Metal Strength

Figure 2 shows the images of two Lavsan samples, one of which was stretched in air, and the other in the adsorption-active fluid. It is clearly seen that in the first case the neck appears in the sample. In the second case, the film is not narrowed, but it becomes milky white and not transparent. The causes of the observing whims are becoming understandable in microscopic examination.

Fig.3. Electronic micrograph of a polyethylene terephthalate sample deformed in n-propanole. (Led. 1000)

Instead of a monolithic transparent neck in the polymer, a unique fibrillary-porous structure is formed, consisting of tumor aggregates of macromolecules (fibrils) separated by microfestoms (pores). In this case, the mutual orientation of the macromolecule is achieved not in the monolithic neck, but inside the fibril. Since the fibrils are separated in space, such a structure contains a huge amount of microfest, which intensively dispel the light and give the polymer milk-white color. Pores are filled with liquid, so the heterogeneous structure is preserved and after removing the deforming voltage. The fibrillar-porous structure occurs in special zones and as the polymer deforms the increasing volume is captured. Analysis of microscopic images made it possible to establish the features of the structural rebuilding in the polymer subjected to Crazing (Fig. 4).

Fig.4. Schematic representation of individual stages of polymer cruise: I --inition Crazov, II - Craise growth, III - Crazov broadening.

Binding on any defect (inhomogeneity of the structure), which are abundant on the surface of any real solid body, the cruise grow through the entire cross section of the stretched polymer in the direction, the normal axis of the tensile voltage, while maintaining a constant and very small (~ 1 μm) width. In this sense, they are similar to the true cracks of destruction. But when the cruise "cuts" the entire cross section of the polymer, the sample does not fall into separate parts, but remains one. This is due to the fact that the opposite edges of such a peculiar crack are connected by the finest threads of the oriented polymer (Fig. 3). The dimensions (diameters) of fibrillary formations, as well as separating their microfucts, is 1--10 nm.

When fibrils connecting the opposite walls of cruises become sufficiently long, the process of their merger begins (at the same time, the surface area decreases, Fig.5). In other words, the polymer undergoes a kind of structural transition from the loose structure to a more compact, consisting of tightly packaged fibril units, which are oriented towards the stretch axis.

Fig.5. A diagram illustrating a collapse of a polymer structure occurring at large deformation signs in adsorption-active fluid, at various stages of stretching

There is a method of separating molecules by adsorption from the solution of those of them, which can penetrate into the pores of this size (molecular-sieve effect). Since the pore size can be easily adjusted by changing the degree of polymer exhaust in the adsorption and active medium (using the rebinder effect), it is easy to achieve electoral adsorption. It is important to note that the adsorbents used in practice are usually a certain powder or granulate, which fill in different types of capacity (for example, a sorbent in the same gas mask). Using the rebatera effect, it is easy to obtain a film or fiber with through nanometric porosity. In other words, the prospect of creating a structural material with optimal mechanical properties and is simultaneously an effective sorbent.

Using the rebinder effect, an elementary path (simple stretching of the polymer film in the adsorption-active medium) can do porous polymer films based on almost any synthetic polymers. The sizes of pores in such films are easy to adjust, changing the degree of polymer deformation, which allows you to make separation membranes to solve various practical tasks.

The effect of the refiner in polymers carries a large applied potential. First, a simple extractor polymer in the adsorption-active liquid can be obtained a variety of polymeric sorbents, separation membranes and polymeric products having a transverse relief, and, secondly, the rebellion effect gives a technological chemist universal continuous method for introducing modifying additives into polymers.

List of materials used

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