WO2002018673A2

WO2002018673A2 - Compound for metal modification and metal surface restoration

Info

Publication number: WO2002018673A2
Application number: PCT/RU2001/000355
Authority: WO
Inventors: Yuri Alexandrovich Chervonenko; Igor Vladimirovich Nikitin; Igor Filippovich Pustovoy
Original assignee: Rvs-Tec Oy
Priority date: 2000-08-31
Filing date: 2001-08-29
Publication date: 2002-03-07
Also published as: DE60129340D1; EP1315847A2; WO2002018673A3; EP1315847B8; AU2001290397A1; RU2169208C1; ATE366832T1; EP1315847B1

Abstract

The invention refers to mechanical engineering and metallurgy and can be predominantly used for the development of cermet alloys and surfaces based on ferrous and nonferrous metals that possessing high tribotechnical characteristics, wear resistance and corrosion stability, and also for restoration of worn-out metal surfaces by forming a cermet layer upon them. The compound represents a mixture with the dispersion of 0.1-10.0 νm that contains serpophite in the amount of 40-70 % of the compound mass; kaolinite, for example amesite, in the amount of 10-40 % of the compound mass; crystallizer, for example pyrolusite, in the amount of 5-10 % of the compound mass; and catalyst, for example metasilicate, in the amount of 5-10 % of the compound mass. The invention provides obtaining cermet layers that process high strength, homogeneity of structure and necessary thickness, the cermet having specified predictable parameters, both in the bulk and at the surface of ferrous and non-ferrous metals and alloys, a long storage time, and a variety of application areas.

Description

COMPOUND FOR METAL MODIFICATION AND METAL

SURFACE RESTORATION

Pertinent art

The invention refers to mechanical engineering and metall rgy and can be predominantly used for the development of ceramic metal alloys and surfaces based on ferrous and nonferrous metals mat possess high tribotechnical characteristics, wear resistance, and corrosion stability, and also for restoration of worn-out metal surfaces by forming ceramic metal (hereafter "cermet") layers upon them. Previous level

There is a known compound that is used in the method of lifetime extension of friction parts and lubricating oils in the process of machine operation (SU 152601, 1969), and represents lumps arranged in the oil case lower part and consisting of tin (stannum), antimony (stibium), or bismuth alloy in the amount of 75.0 - 96.5% of the mass of alloy, with sodium in the amount of 3.5 - 25% of the mass of alloy, or the alloy of tin, antimony or bismuth in the amount of 90,0 - 98.8% of the mass of alloy, with Hthium in the amount of 1.2 - 10.0% of the mass of alloy, and also halides, for example iodine, bromine, chlorine, or fluorine, added to lubricating oil in the amount of 0.02 - 0.08% of the mass of alloy. In the course of operation of a machine, halide reacts with anti-friction alloy components of the friction surface with formation of halogenides of these components on the surface possessing high anti-fiiction properties. Alkaline metals contained in the alloy react with water contained in lubricating oil, which results in the destruction of the alloy components - tin, antimony or bismuth, whose fine particles react with halide. Fine particles of tin, antimony or bismuth halogenides diffuse, under the high pressure effect of lubricating oil, into anti-fiiction alloy of the friction surface, which results in restoration of the surface by covering it with a thin, elastic, wearresistant layer of soft metal. Another known mixture is used in the method of roller bearing processing prior to operation (SU 1196552, 1985); it contains copper powder in the amount of 16 - 20 % of the mass of the mixture, lead powder in the amount of 4 - 6 % of the mass of the mixture, polytetrafluoroethylene powder in the amount of 1 - 2 % of the mass of the mixture, and soap lubricant grease in the amount of 72 - 79 % of the mass of the mixture. Introduction of designated mixture into roller bearing provides the finish upgrading and reduces the friction coefficient and wear intensity. Besides, there is a known lubricant that is used in the method of friction pair processing (SU 1668471, 1991), and contains lubrication oil, metal- containing additives, for example copper- or zinc-based, and abrasive particles, for example of aluminium oxide with dispersity up to 10 μm. After lubricant application, the friction pair performing the function of cathode, is treated under operating load, speed and temperature, with an anode insulated from friction pair and made of additive material introduced into lubrication zone. Particles of additive metal are deposited first of all within the surface microroughnesses, which improves the fineness of the friction surface treatment. Fine abrasive particles deposited along with metal particles improve the wear resistance of the deposited metal coating.

All said known compounds based on metal powders and organic binder improve the wear resistance only due to friction coefficient reduction, being a result of either surface smoothing, due to filling of the friction surface microroughnesses with particles of the compound, or formation at the surface of chemical compounds with high antifriction properties. In some cases it is accompanied by the formation at the friction surface of finest films that negligibly compensate their wear. However, the drawbacks of said compounds are the low strength and corrosion resistance of friction surfaces obtained with their aid. The following tribotechnical compounds are known to form a film on friction surfaces with a predominant content of iron based on fine-grained mixture of minerals and organic binder:

-compound for film formation on friction surfaces (SU 1601426, 1990), representing a mixture of abraded natural quartz in the amount of 0.1 — 5.0 % of the compound mass and organic binder in the amount of 95.0 - 99.9 % of the compound mass;

- process agent used in the method of friction joints restoration without dismantling (UA 24442 A, 1998) and consisting of the base oil in the amount of 80.00 - 99,85 % of the process medium mass and powdered rehabilitation compound with the dispersity of 10-30 μm in the amount of 0.15 - 20.00 % of the process medium mass, containing a natural mineral or mixture of natural minerals, comprising amorphous silicon dioxide in the amount of 40 - 50 % of the composition mass and catalysts on the basis of shungite and rare-earth metals in the amount of 0.02 - 2.00 % of the composition mass;

-mixture of abrasive-like powder with binder, such as dispersed stearin, which is used in the method of servovite film formation by tribotechnical compound (RU 2035636, 1995), said abrasive-like powder containing serpentine in the amount of 51 - 60 % of the powder mass, talcum in the amount of 20 - 40 % of the powder mass and taken in equal portions sulfur, pyrrhotine, enstatite and fayalite, all in all in the amount of 8 - 10 % of the powder mass;

- mixture of abrasive-like mineral powder with dispersity of 4-10 μm, for example in the amount of 2 % of the mixture mass, and binder for example in the amount of 98 % of the mixture mass, used in the method or rubbing surfaces modification (RU 2093719, 1997) and comprising the designated abrasive-like mineral powder of chrysotile in the amount of 20 - 40 % of the powder mass, kaolinite in the amount of 40 - 60 % of the powder mass, lanthanum oxide in the amount of 2 - 4 % of the powder mass, yttrium oxide in the amount of 2 - 4 % of the powder mass, aluminium oxide in the amount of 2 - 8 % of the powder mass and iron oxide in the amount of 6 - 7 % of the powder mass.

Said tribotechnical compounds, according to the above-mentioned methods, are subjected to mechanical activation differing in conditions and means of achievement, arranged between friction surfaces, and bedded in. The formed servovite films restore the worn friction surfaces and possess the cermet properties, due to which they favor the enhancement of corrosion and wear resistance and decrease of the friction coefficient.

However, said servovite films possess low durability due to fragility and possible lamination, and also non-uniformity of thickness and structure heterogeneity, which is the result of the nature of their formation process at the bedding-in stage, which is rather spontaneous than controllable. Such servovite films can only be formed on friction surfaces with a predominant iron content, and therefore the designated known tribotechnical compounds cannot be used for modification and restoration of friction surfaces made of other metals and alloys. Besides, the process of servovite film formation is connected with bedding-in process in the operating mode or similar modes, which restricts the area of tribotechnical compounds application, as it enables to apply them for the purposes of modification and restoration of friction surfaces only, and exclusively when a machine is repaired without dismantling.

As the closest to the proposed compound for metal modification and metal surface restoration in both its chemistry and the achieved technical result achieved, the rehabilitation compound may be considered that is used in the method of formation of protecting coating selectively compensating the wear of friction and contact surfaces and the machine parts (RU 2135638, 1999, C 23 C 26 / 00). The rehabilitation compound chosen to be the prototype is used for wear resistant coating deposition upon friction and contact surfaces of iron-based alloys, and contains fine- grained mixture with the dispersity of 5 - 10 μm of ophite in the amount of the compound mass, shungite in the amount of 1 - 10 % of the compound mass and catalyst in the amount up to 10 % of the compound mass.

According to the mentioned method, this rehabilitation compound is introduced into standard lubricant and delivered along with the lubricant to friction surfaces, after which the friction surfaces are bedded in for 0.5 - 1.5 hours, and cermet protective coating of f iction surfaces is formed in the course of machine operation.

In the process protective coating formation under machine operation, the temperature in f iction surface micro volumes rises, under the effect of friction, to 900 - 1200 °C. Under such conditions, reactions of replacement of magnesium atoms by iron atoms from crystal lattices of either steel or iron alloy, of which the friction surfaces are manufactured, occur in the sites of crystal lattices of ophite and nephrite, being the components of the rehabilitation compound. In this case, new heteroatomic crystals are formed, having more extended spatial structures, which contributes to the formation of a protective coating that compensates the preliminary wear of friction surfaces. The formed cermet protective coating has a higher thickness and higher wear and corrosion resistance. However, the process of the protective coating formation during machine operation is of a spontaneous, uncontrolled character, which results in the non-uniformity of its thickness and structure heterogeneity, and does not allow to obtain protective coatings with specified predictable parameters. This feature, and the non-identity of the spatial configuration of the crystal lattice of ophite and nephrite minerals used as basic components of the known rehabilitation compound, result in an insufficient strength of the formed cermet protective coating. The scope of use of the known rehabilitation compound is restricted by its application to restoration of friction surfaces made exclusively of iron-based metals and alloys, and in the process of machine operation only. Besides, the known rehabilitation compound has a limited storage time, which is related to the increase of the compound dispersity with time due to so-called cohesion, provided by coagulation of individual particles of the compound with each other under the effect of Van der Waals forces. Invention disclosure

The purpose of the invention is to provide a compound for modification of metals and metal surface restoration, forming a cermet that possesses high strength, structure homogeneity and thickness uniformity, with specified predictable parameters, both in the bulk and on the surface of ferrous and non-ferrous metals and alloys, having a long storage time, and also allowing for the application range extension of said compound.

This purpose is achieved, according to the invention, in such a way that compound for modifying metals and restoring metal surfaces containing fine-grained mixture of serpophite and catalyst in accordance with the prototype differs from the prototype by additionally containing kaolinite and crystallizer at the following component ratio: serpophite - 40 - 70 %, kaolinite - 10 - 40%, crystallizer - 5 - 10% and catalyst - 5 - 10% of the total compound mass. Here the mixture dispersity is 0.1 - 10.0 μm, amesite is used as the kaolinite, pyrolusite is used as the crystallizer and metasilicate is used as the catalyst.

The designated distinctive properties have not been discovered in the known analogues.

The combined use of the serpentine group as the mineral that has the very .kaolinite type crystal lattice of serpophite and kaolinite, for example amesite, in the proposed compound for modifying metals and restoring metal surfaces provides higher strength and homogeneity of modified metals, as well as larger thickness, homogeneity and durability of the restored metal surface with a simultaneous enhancement of the binding of the layer with the surface on which it is formed. This is explained by the following circumstances that are elucidated by the example of using the proposed compound for the purposes of metal surface restoration under the machine repair without dismantling, when the compound is mixed with organic binder, for example, standard lubricating oil and introduced at the friction surfaces, after which the bedding-in of the friction surfaces is carried out in the operation mode.

Under the effect of friction, the cleaning of the friction surface microrelief is carried out by fine particles of minerals, being the components of the proposed compound, and these particles are work hardened into the purified microrelief of the friction surfaces. The friction and grinding of the particles of the compound on the friction surfaces and the clean-out of the microroughness of these surfaces induce energy evolution, resulting in the surfaces being treated heating up to the temperature of 700-1200 °C in the microvolumes of the friction surfaces. Similar heating renders the surface layers of the friction body metal up to either fluidity or a state close to it. This results in intensive diffusion of particles of the proposed compound into the surface layer of the metal.

As noted above, the basis of the proposed compound are serpophite, corresponding to the formula of Mg₃[Si₂θ₅](OH) and kaolinite, for example amesite, having the formula of (Mg₂Al)[(SiAl)0₅](OH)_4. At the particle dispersity of the indicated minerals, comparable to dimensions of elementary crystals, under conditions of high temperatures, such reactions take place, in which the metal atoms of the friction surfaces substitute the magnesium atoms at the sites of the serpophite crystal lattice and magnesium and u ninium atoms at the sites of the amesite crystal lattice. In this connection the atoms of the friction surface metal replace, first of all, those magnesium and aluminium atoms that are located at the sites of the surface layers of serpophite and amesite crystal structures respectively.

As the activity of the aluminium atom ions contained in the amesite is essentially higher than that of magnesium atom ions, aluminium atoms at the sites of the amesite crystal lattice can be replaced not only by iron atoms of the friction surfaces, but also by atoms of basic nonferrous metals used in mechanical engineering, as for example those of copper and zinc. Therefore the proposed compound can be used for modifying and restoring surfaces of both ferrous and non-ferrous metals and alloys.

The use of metasilicate as a catalyst and a lower dispersity of the compound enable to reduce to 400 - 700 °C the temperatures in micro- volumes of the friction surfaces, on which the designated substitution reactions take place. As a result, the cermet layer is formed on the friction surfaces being restored.

The basis of the proposed compound are serpophite and one of kaolinites, for example, amesite, that possess an identical, so-called kaolinite-like structure of the crystal lattice. They represent fibrous-tubular and coiled (roll) conglomerate crystals composed of a complex composition of octahedral- and tetrahedral-type plane crystals. Owing to the identity of the crystal lattice structures, the designated minerals appear to be more compatible, and therefore the obtained cermet layer possesses higher strength, durability, and structural homogeneity, and it also has stronger bonding with the friction surface being restored. Besides, the use of serpophite and kaolinite, such as amesite, that possess more extended spatial structures of their crystals than minerals used in the known compounds, promotes the increase of the cermet layer thickness of the surface being restored. Pyrolusite used in the proposed compound as a crystallizer has the formula of Mn0₂ • H₂0, i.e. it contains constitution water in a bound state and provides the accomplishment of control function of the cermet layer formation process. The choice of the dispersity and the per--cent content of pyrolusite in the proposed compound enables to ensure the opportune liberation of a necessary amount of the bound constitution water with the account of both the current temperature values in the micro volumes of the surface being restored and the time of its effect, and thus to stimulate the opportune cooling and crystallization of the formed cermet layer, when its parameters achieve the specified predicted values. This provides the controllability of the process of ceramics metal formation with such specified predictable parameters as the thickness, microhardness and roughness of ihe layer, which depend on the number of bonds formed as a result of the substitution reactions, i.e. on the temperature and the time of its occurrence. Besides, the pyrolusite available in the proposed compound as a crystallizer prevents the coagulation of fine-grained particles of the compound and their sticking to each other due to the enveloping ability of the aqueous films resistance to destruction, which are formed from water evolved from the crystallizer. As a result, no essential dispersity increase occurs during the storage of the compound. Therefore, the admissible storage time of the proposed compound can be considerably extended.

The practice has shown that heating required for the reaction of substituting the metal atoms of the surface being treated by magnesium and aluminium atoms at the crystal lattice sites of serpophyte and amesite respectively, of which the latter represents the kaolinites, can be achieved not only due to the friction of the surfaces being treated under bedding-in and operation of the machine, but also by other forms of energetic effects. In these cases the process of the cermet formation is accompanied by physico-chemical processes similar to those described above, and an analogous technical result is achieved. The above-mentioned confirms the application area extension of the proposed compound, as it can be used both in combination with organic binder, for example standard lubricating oil, and without it, for modifying and restoring not only friction surfaces, but also other types of units and parts under different techniques of energetic effect production, examples of which will be given below. Variants of invention realization

The facts mentioned above are evidence of the importance of the designated distinctive properties of the proposed invention.

The proposed compound for modifying metals and restoring metal surfaces represents a mixture with the dispersity of 0.1 - 10.0 μm, which contains serpophite in the amount of 40 - 70 % of the compound mass, kaolinite, for example amesite, in the amount of 10 - 40% of the compound mass, crystallizer, for example pyrolusite,- in the amount of 5 - 10% of the compound mass, and catalyst, for example metasilicate, in the amount of 5 - 10% of the compound mass.

The designated qualitative and quantitative ratio of the compound components is the most acceptable, and when it falls beyond the scope of the claimed ratio ranges, the technical result declared above is not achieved. The necessary range of the compound dispersity is also the most acceptable, as UΪQ increase of the compound particle sizes above 10 μm results in essential productivity decrease of the cermet formation process, and the decrease of the cermet homogeneity, while the decrease of particle sizes to the values below 0.1 μm also results in productivity decrease, as the intercrystalline bonds in the minerals used in the compound are broken. The proposed compound may be manufactured in the following basic stages: separate crashing and grinding of the minerals to the required dispersity, using known milling devices; classification, providing for selection of the milled mineral by sizes, density and mass of particles by means of separation; fine purification from impurities and concomitant substances, and also the benefication; component mixing; drying - to decrease water content. Possible scopes of application and variants of the proposed compound for metal modification and metal surface restoration, as well as the attained technical results are illustrated by the following examples. Example 1. The proposed compound containing serpophite in the amount of 50 % of the compound mass, amesite in the amount of 40% of the compound mass, pyrolusite in the amount of 5 % of the compound mass, and metasilicate in the amount of 5 % of the compound mass, with industrial oil as an organic binder, was introduced via a filler into a standard lubricant of an of a GAZ-3110. "Volga" car internal combustion engine, with the parameters as follows: average pressure in the combustion chambers of the cylinders - 0.7 MPa; oil pressure in the engine lubrication system at the temperature of 70° C - 0.14 MPa; fuel consumption per 100 km of mileage - 12.5 liters. After the bedding-in of the engine in an operation mode during 5 hours, its parameters changed as follows: average pressure in the combustion chambers of the cylinders - 0.92 MPa; oil pressure in the system of engine lubrication at the temperature of 70° C - 0.22 MPa; fuel consumption per 100 km of mileage - 10.4 liters.

In 100 hours of the engine operation, after the car haulage of about 8000 - km the designated parameters have not practically been changed. Example 2. The proposed compound^ containing serpophite in the amount of 70 % of the compound mass, amesite in the amount of 20% of the compound mass, pyrolusite in the amount of 5 % of the compound mass and metasilicate in the amount of 5 % of the compound mass, along with standard lubricant, on the basis of 0.002 g of the compound per 100 g of standard lubricant, was placed into the f iction area of roller bearings of Type 204 produced by the Vologda State Bearing Factory (Russia) and by SKF, and of slider bearings manufactured in the laboratory of "Vserossiysky Nauchno-Issledovatelsky Institute podshipnikovoiy promyshlennosty" (All-Russia Research Institute of Bearing Industry), Moscow, Russian Federation. The bearings were subjected to bedding-in under operating conditions for 1-5 hours.

The functional surfaces of external and internal rings, and the rolling elements of the roller bearings had the roughness of 0.08-0.10 μm and the microhardness of - 58-59 HRC. After the bedding-in their roughness was 0.013-0.020 μm and microhardness - 60-62 HRC, the radial gap being decreased by 1.0 - 1.5 μ .

The sliding bearing manufactured from steel with subsequent quenching had the roughness of functional surfaces of 5.5-5.7 μm and the microhardness of - 38-40 HRC. After the bedding-in its roughness was 0.8-1.4 μm and the microhardness - 46-48 HRC. The tests and measurements were carried out according to standard methods used in the bearing industry of the Russian Federation, at the facilities of All-Russia Research Institute of Bearing Industry (JSC), Moscow, Russian Federation. Example 3. The proposed compound containing serpophite in the amount of 40

% of the compound mass, amesite in the amount of 40% of the compound mass, pyrolusite- in the amount of 10 % of the compound mass, and metasilicate in the amount of 10 % of the compound mass, was added to a mixture of industrial oil and kerosine, placed in industrial solvent tank with magnetostrictive unit (magnetostrictor). Samples of roller bearings of the type 302 and drills of different diameters were processed in the tank during 10-60 minutes by using ultrasonic radiation with the power of 0.4 - 4.0 k and the frequency of 22 - 24 kHzr

After treating of the roller bearings with the compound, their operation time,-without lubricating till seizure under the loads of 40-80 kg and rotation with angular velocity of 42 s^"1 , increased from 5-6 min up to 46- 50 min, and the time of cutting steel by drills till cutting edge fusion and cutting angle change under loads of 10-45 kg increased from 9-10 min up to 37-40 min. The tests were carried out at the testing laboratory base of

Gorelectrotrans municipal enterprise, Magnitogorsk, Russian Federation. Example 4.

Parts of steel after dry deposition upon them of the proposed compound containing serpophite in the amount of 45 % of the compound mass, amesite in the amount of 40% of the compound mass, pyrolusite- in the amount of 10 % of the compound mass, and metasilicate in the amount of 5 % of the compound mass, were placed into an industrial muffle furnace and processed at the temperature of 700-1100 °C during 1.0-1.5 hours. After such treatment the microhardness of the parts had increased by 8-10 HRC on the average, and the friction coefficient had lowered approximately to one third, and achieved the values of 0.007-0.009.

Example 5.

In the laboratory of experimental melting of OAO "SeverstaT",

Cherepovets, Russian Federation, an experimental melting was carried out by using the mixture of cast iron with the microhardness of 22 HRC in the amount of 80 % of the mixture mass, and the proposed compound in the amount of 20 % of the mixture mass, containing serpophite in the amount of 50 % of t e compound mass, amesite in the amount of 40% of the compound mass, pyrolusite in the amount of 5 % of the compound mass, and metasilicate in the amount of 5 % of the compound mass. The obtained cermet alloy possessed the microhardness of 42 HRC.

Example 6.

The proposed compound containing serpophite in the amount of

55 % of the compound mass, amesite in the amount of 35% of the compound mass, pyrolusite in the amount of 5 % of the compound mass, and metasilicate in the amount of 5 % of the compound mass, was introduced into the lubricating oil of a compressor, after which the compressor was bedded-in under operating conditions. The analysis of connecting rod pins of the low and high pressure cylinders of the compressor made of steel and carbon steel respectively was carried out in the physical metallurgy laboratory of the State Technological University in Chita, Russian Federation. The analysis showed that sufficiently homogeneous cermet layers were formed on said pins with the thickness of 25-40 μm and 20-50 μm respectively and the microhardness of 60-74 HRC, with the initial microhardness of the connecting rod pins of 30-40 HRC.

Example 7.

The proposed compound containing serpophite in the amount of 50 % of the compound mass, amesite in the amount of 40% of the compound mass, pyrolusite in the amount of 5 % of the compound mass, and metasilicate in the amount of 5 % of the compound mass, was introduced into the standard diesel engine lubricating oil of a diesel locomotive that was in operation for 6 months.

The tests showed that cermet layers were formed on friction surfaces made of both ferrous and nonferrous metals. For example, due to cermet layers formed on a cylinder bushing and ring made of copper and chromium respectively, their service life between repairs increased by approximately a factor of 2.7. The formed cermet layers noticeably decreased the friction coefficient between the shaft and the slider bearing made of steel and babbit respectively, which resulted in an increase of the impeller angular velocity by 13-28 %. The decrease of fuel consumption was noted to be 16 - 24 % with the diesel engine running idle, its power output simultaneously increasing.

The tests were carried out at the research facility of the Zabaiykalsky Railway Transport Institute, Chita, Russian Federation. Example 8.

The proposed compound was applied to restore of irregularly worn surfaces of Beumer automatic palletizer guides, and to increase their lifetime, at OAO Dry Mixtures Pilot Plant, Moscow, Russian Federation. The compound contained serpophite in the amount of 70 % of the compound mass, amesite in the amount of 18 - 20% of the compound mass, pyrolusite in the amount of 5 -7 % of the compound mass, and metasilicate in the amount of 5 % of the compound mass, and was deposited upon surfaces of guides along with the standard lubricating oil as an organic binder.

Due to irregularity of the wear rate, in order to restore the horizontal position of the automatic palletizer guide surfaces, the compound was deposited on their different sections with different contents of amesite and pyrolusite and with a different dispersity. For the sections of the guide surfaces with the highest wear rate, the compound was used with the dispersity of 5 - 7 μm and the amesite content of 20% of the compound mass, and pyrolusite, in the amount of 5 % of the compound mass, while for the sections with the lowest wear rate, the applied compound had the dispersity of 1 - 3 μm and the amesite content of 18 % of the compound mass, and pyrolusite, in the amount of 7 % of the compound mass.

After the bedding-in of the automatic palletizer under operating conditions, the guide surfaces were leveled due to cermet layer formation with the thickness from 0.1 to 1.1 μm at different sections, depending on the amesite and pyrolusite content and the dispersity, in accordance with the value of the preliminary wear. Besides, the gap between the guides and the carriages moving along them was decreased by 1.0-1.5 μm. This example confirms the controllability of the cermet layer formation process, and formability of a layer with specified predictable parameters, such as thickness, by varying the compound dispersity value and the content of pyrolusite as a crystallizer. Industrial applicability

The proposed compound for metal modification and metal surface restoration, due to serpophites and kaolinites contained therein, such as amesite, provides obtaining both the structure of modified metal, possessing high strength and homogeneity, and the restored metal surface with larger thickness, homogeneity and durability, with simultaneous bond strengthening of the restoring cermet layer with the surface of its formation.

The use of pyrolusite as a catalyst in the proposed compound, with the variable content of amesite and pyrolusite in the compound, and variable dispersity, makes the process of the cermet layer formation controllable, which enables to obtain cermet layers with specified predictable parameters such as the layer thickness, microhardness, and roughness. Besides, pyrolusite contained in the proposed compound prevents its dispersity from increasing during the storage of the compound, offering an essential increase of its storage time.

Due to kaolinite contained in the proposed compound of kaolinite, for example amesite, it can be applied in the industry for surface modification and restoration of both ferrous and nonferrous metals and alloys. Since heating necessary for the cermet layer formation can be obtained in the application of the proposed compound by several types of energetic effects, for example, by friction of the surfaces being processed, by thermal heating of completed parts, melting of a mixture of a metal and the proposed compound, treatment of part surfaces by ultrasonic radiation, or otherwise, the proposed compound may be applied not only to the modification and restoration of metal surfaces, but also for the modification of metals and alloys throughout their whole bulk. Such diversity of energetic treatment methods during metal modification and metal surface restoration greatly expands the scope of the industrial appticability of the proposed compound.

Claims

FORMULA OF INVENTION 1. Compound for metal modification and metal surface restoration containing a fine-grained mixture of serpophite and catalyst, different from others in that it additionally contains kaolinite and crystaUizer at the following component ratio of the compound total mass: serpophite - 40 - 70%, kaolinite - 10 - 40%, crystallizer - 5 - 10%, catalyst - 5 - 10%.

2. Compound as claimed in 1., different from others in that the mixture dispersity is 0.1 - 10.0 μm.

3. Compound as claimed in 1., different from others in that amesite is used as kaolinite.

4. Compound as claimed in 1., different from others in that pyrolusite is used as crystallizer.

5. Compound as claimed in 1., distinctive in that metasilicate is used as catalyst.