ES2654858B1 - METHOD FOR PREPARING A METAL SUPPORT - FLEXIBLE CERAMIC THAT HAS A NANOCRISTALINE SURFACE LAYER - Google Patents

Abstract

Method for preparing a flexible metal-ceramic support having a nanocrystalline surface layer. # The invention relates to the field of the production of ceramic coatings, which have a developed surface, on metal objects having complex shapes, and can be use in applied chemistry to prepare catalyst elements, in mechanical engineering, shipbuilding, the aviation industry, and in the preparation of space technology objects when protective coatings are applied, including anti-corrosion coatings, thermal barrier coatings, resistant coatings the formation of ice, and other coatings. One method of preparing a flexible metal-ceramic support having a nanocrystalline surface layer includes plasma spraying of a special aluminum-based coating on a metal strip support, with subsequent hydrothermal processing of the flexible semi-finished product. The invention is novel since the hydrothermal processing, which provides for an optimal microstructure, nanostructure and porosity, is carried out in two phases, in which the first processing phase is carried out at a pressure of 20-26 atm. and temperatures of 200-230 degrees Celsius for 6-12 hours, and the second phase is carried out at a pressure of 4-8 atm and temperatures of 150-170 degrees for 120-160 hours.

Description

METHOD FOR PREPARING A METAL -CERAMIC SUPPORT

FLEXIBLE THAT HAS A NANOCRISTAL SURFACE LAYER

Technical Field 5 The invention relates to the field of coatings production of

ceramics, which have a developed superticia, on metal objects that

they have complex shapes, and can be used in applied chemistry to prepare catalyst elements, in mechanical engineering, shipbuilding, the

aviation industry, and in the preparation of space technology objects

10 when protective coatings, including anti-corrosion coatings, thermal barrier coatings, ice-resistant coatings, and other coatings are applied. Prior art The application of ceramic coatings on a metal support is

15 widely used in industry, allowing to provide reliable protection against various exposure factors to both a natural and artificial environment. For example: document CN101438439, 20 -05-2009, A multi-Iayer coating, Halvor Larsen Peter; EP2088225 (A1), 12-0-2009,

20 Erosion and corrosion-resistant coating system and process therelor, Pabla Surinder Singh; document CA2664929 (A1), 03 -04-2008, Method and device lar depositing a non-metal coatings by means 01 cold-gas spraying, Luethen Volkmar; document CA2668736, 15 -05 -2008, A method lor the production 01 thin layers 01 metal-ceramic composite materials, Ciasen Rolf,

25 However, ceramic coatings on a metal substrate

they have a number of disadvantages that arise from the specific details of their

nature. First, it concerns a significant difference in the

linear expansion coefficient (LEC) for ceramics and metals (see table 1),

30 Table 1, CoefIClente de d'l I ataclon "rIneaIl for material is metal and ceramics

Kind of

Material Coefficient of thermal expansion at 20 2C,

material

x 10 "/ K

Metal

Faith 11, 1

Steel

10.8

carbon

Type of material

Material Coefficient of thermal expansion at 20 oC, x 10 "/ K

Stainless steel

17.3

Neither

13

To the

2. 3

Ceramics

Glass 8.5

Therefore, when using a metal-ceramic composite material a

elevated or reduced temperatures, which is necessarily associated with the

heating and cooling process, thermal stresses appear

5 raised on the border between metal and ceramics, which can lead, in

in many cases, to structural distortions of both the metal substrate and the ceramic coating and, in some cases, the destruction of the ceramic layer, appearing as a serious delamination of the coating or

even exfoliation.

10 The situation becomes even more serious when the coating is used in conditions of thermal shock and thermal cycles with simultaneous exposure to factors such as corrosion or gas erosion.

To compensate for thermal stresses, intermediate layers that are located between the metal substrate and the ceramic lining are often used, thereby providing complete or partial relaxation of

the thermal stresses that arise in the intermediate layer.

Very extreme requirements are imposed on the intermediate layers, in particular, these must provide reliable adhesion to both the substrate metal and the ceramic coating, to provide rapid

20 stress relaxation at its minimum level due to plastic deformation, which is possible only with the maximum plasticity of the intermediate layer material. In addition, the intermediate layer material should see its fragility increased to a minimum during the application of temperature gradients (or the increase in fragility should be released by means of relaxation mechanisms

25 specific only during operation). In addition, based on general provisions, the intermediate layer should have a minimum thickness. All this imposes a range of serious restrictions on the material of

intermediate layer and dramatically limits the range of materials that can be used for these purposes.

As an intermediate layer, metals such as aluminum, nickel and copper are often used, which, together with high plasticity, have good adhesion to the metal and ceramic substrate, as well as high processability, thereby allowing the use of processes existing technologies such as thermal spraying (plasma spraying and flame spraying), magnetron and ion plasma spraying, as well as electrolytic coating methods.

When the efficiency of these layer application methods is estimated

intermediate from the point of view of adhesion to a metal (steel) substrate, preference may be given only to the magnetron and ion plasma spray methods, which are preferred over the methods of

thermal spraying, taking galvanic methods after all

others. The main advantage of physical deposition methods (magnetron and ion plasma spraying) is the gradual layer-to-layer deposition of

metal ions, in which the first layer adheres firmly to the substrate superlicial layer and then the subsequent layers adhere

pertectly to the first layer, the second layer, etc. A disadvantage

Significant of these methods is a very low rate of this growth of the intermediate layers.

Therefore, these methods can be applied only to create a layer

intermediate adhesive and cannot be used to obtain a layer of a support

of catalyst on a substrate of metal substrate. To obtain a catalytic support layer, other spray methods should be used or

deposition to provide a layer of sufficient thickness that ensures

a high degree of superticial development.

Therefore, for example, technical solutions are known in which a very thin layer of aluminum is used as the intermediate layer that is deposited by the ion plasma method on the surface of a steel strip. Next, a layer of an aluminum oxide-based catalyst support with alpha modification is applied to its surface by the plasma method.

When thermal and galvanic spray methods are used, it is possible to obtain sufficiently thick coatings that can be used as adhesive coatings, as well as forming a support layer of

catalyst on its surfaces.

A solution is suggested by a series of patents.

For example, US Pat. UU. with n '5,362,523 in the name of Garinin

1. V., Farmakovsky B. V., Khinsky A. P., et al. , 1994, describes a method for

produce a catalyst strip material that includes a steel substrate, which is first covered with an adhesive sublayer by the plasma spray method and then covered with a coating

of multiple catalyst layers by the same method in which the

The concentration of catatatically active elements gradually increases in the border between the adhesive sublayer and the catatatically active layer at

100% above the surface. The increased adhesion strength between the adhesive layer and the steel substrate is achieved due to the formation of an efficient diffusion layer in the contact zone between the adhesive layer and the substrate.

U.S. Patent UU. with n. ' 5,820,940 in the name of Garinin 1. V., Farmakovsky B. V., Khinsky A. P. et al., 1998, describes a method for

produce an adhesive coating (intermediate layer) on a strip support

of metal by plasma spraying of thermally reactive composite powders (such as nickel-aluminum). The method as it is

describe provides an intermediate adhesive layer that adheres very

closely to the steel strip support, which is demonstrated by the test results. However, the problem of reliable adhesion of the catalytic layer that is deposited on the surface of the intermediate layers remains unresolved and the

Adhesion strength between these layers, although not mentioned in the patent materials, will obviously be lower than the bond strength between the intermediate layer and the metal substrate. When using elements of

catalyst made of a catalyst strip material of this type, in

extreme conditions, including thermal cycles, intensive gas erosion,

etc. , a partial delamination of the catalyst layer together with

a corresponding decrease in its characteristics. Attempts to increase the bond strength between the intermediate layer and the catalyst layer through an intermediate thermal processing (the

US2001014648, Hums E., Khinsky A., 2001), through the use of

various places to introduce powdered materials into the stream of

plasma during the spraying process (document W02004079035, Khinsky A P., 2004), through the use of the HVOF (high velocity oxygen fuel) method of spraying composite powder (the document W02008063038, Khinsky A. P, Klemkaite K., 2008) lead to a certain increase in adhesion strength, if

well they don't provide a high level of bond strength between the layer

intermediate and metal substrate.

The use of coatings that are obtained by thermal spraying of metals and ductile alloys (aluminum, nickel, copper, etc.) provides a high adhesion to the pulverized surface due to the high kinetic energy of the particles being sprayed (often, spraying

it is carried out at speeds close to, or even higher than, the speed of sound) and the high dynamics of its cooling, which almost always leads to depreciation (or the transition to the state

microcrystalline) of the metal particles being sprayed.

However, the compounds that form during contact

instantaneous between the molten particles and the metal substrate during the

course of the thermal spray process, which are mainly

intermetalides of a different composition and stoichiometry that form in the contact zone as very thin films, differ

considerably in terms of its physical-mechanical characteristics with

with respect to the usual intermetalides, which are formed during the course of conventional metallurgical processes, including casting, thermal processing, etc., of special steels and alloys. It is known that conventional intermetalides that are formed under the same conditions are characterized by high hardness and fragility, while non-stoichiometric film intermetalides that are formed during the course of thermal spraying, as practice shows, do not exhibit such properties and, in addition, they provide very good adhesion of

the layer sprayed to the substrate.

The coatings obtained by the thermal spray method provide another important advantage over the galvanic method and the magnetron and ion plasma spray methods. This advantage lies in the ability to form a superstructure microstructure during the

thermal spray The typical thickness of such a coating is 10-20 m.

The structure of the pulverized layer surface can be significantly improved due to the formation of "protuberances"

Nanostructured in the form of nanocrystals of different configurations

(A. V. Lukashin, C03A8HVl8 CPYHKL \ V10HanbHblx H8HOKOMn03l-1TOB Ha DCHOBe OKC "AHbIX MaTp" ~ c ynopoA04eHHoi1 nOp "CToi1 CTpyKTypOi1, ABTopecj, ept.

The creation of nanostructures on the surface of this type increases

Catalyst activity, resistance to ice film formation to

temperatures below zero, the optical characteristics of the coatings etc. Therefore, the use of coatings that are obtained by thermal spraying (especially plasma spraying) as a layer

In addition, in addition to obtaining a high adhesion of the sprayed layer, it is possible to provide for the formation of its developed microstructure. The application of a catalyst support layer (with or without catalyst as such) on the intermediate layer can be carried out in various ways;

however, in any case, the applied layer must provide the following characteristics:

-

A free surface high enough with an optimal porosity structure; -High adhesion strength between the catalyst support layer and the layer

intermediate;

-

A sufficiently high level of catalytic properties when interacting with the catalyst as such.

Unfortunately, virtually all existing methods of applying a catalytic support cannot provide a high level of catalytic properties and high adhesion to the coating.

intermediate at the same time. Therefore, the choice of the optimal method to form a catalyst support layer on metal substrates is to

often very difficult.

Furthermore, the manufacturing process comprising said intermediate phases, that is, the application phase of the intermediate adhesive layer and the subsequent application phase of the catalyst support and possibly also the catalyst application phase, is very complicated and expensive.

Therefore, for example, when a catalyst support that is

comprised in an aqueous suspension is applied on a cellular structure

of metal by the method of successive immersion and drying, a very important factor

Annoying that limits the wide applicability of this method lies in the slow drainage of the suspension through the holes during the course of drying and the formation of specific icicles in the lower part of the cell structure, which can lead, in some cases , to the complete blocking of its holes.

From this point of view, it seems very advantageous to combine the processes

of the adhesive coating spray (intermediate layer) and the

subsequent transformation of its surface into a catalyst support r. In

the present case, on the other hand, ensures high adhesion of the

adhesive coating to the metal substrate which, as mentioned above, is characteristic for the coatings that are applied

by the method of plasma purification and, on the other hand, the organic transition of the coating metal to the oxide (or hydroxide) phase. In general, ductile metals and alloys are used, in particular aluminum, nickel, copper and their alloys as the adhesive coating material such

as mentioned above. In general, under certain conditions, all of these materials can be transformed from the surface into oxides and hydroxides, which is seen

accompanied in some cases by a concomitant development of a

porous structure The latter circumstance is very important for the purpose of forming catalytic coatings.

However, for the metals that have been listed above,

which are used to apply an adhesive coating, structure formation

Porous that is required for the catalyst support is observed only in the case of aluminum.

Under certain conditions, aluminum and a series of its alloys can be converted from the surface into aluminum hydroxide. Under ordinary conditions, a thin and very dense oxide film is formed on the aluminum metal surface, which is instantly restored after its destruction. This film prevents oxidation of additional aluminum. However, under certain conditions - at a high pressure and temperature in the atmosphere of superheated steam - a gradual transition from aluminum to aluminum hydroxide (boehmite) is observed. As shown in a series of studies, this process is carried out through the

successive hydration of the oxide film that forms on the aluminum metal surface.

In a series of articles (Tihov SF, Fenelonov BB, et al., K "HeT ~ Ka" KaTan ~ 3, 2000, Vol. 41, n. '6, p. 907-915. Tihov SF, Zaykovskiy V. 1 . et al., K "HeT" Ka "KaTan" 3, 2000, Vol. 41, n. '6, p. 916-924), it is shown that this

The process can be used to produce porous cellular ceramic supports based on aluminum oxide.

The articles describe a process for the preparation of a composition of aluminum oxide / metal aluminum metal-porous ceramic when processing aluminum powder briquettes with a sufficiently high porosity (enough for the free circulation of air inside). The processing was carried out in a special autoclave press, which

ensures the processing of the briquette in an atmosphere of water vapor at a temperature of 150 to 250 'C and a pressure of 5 to 50 atmospheres. A patent (RU2256499 (Cl) of Pakhomov N. A., Tikhov S. F. et al., 2004) is also known, based on the technology described in the

articles. The present patent suggests a ceramic catalyst for a process

of hydrocarbon dehydrogenation and a method for preparing it.

The catalyst composition contains chromium oxide and an alkali metal that is applied on a support, which represents a composite material that includes aluminum and aluminum oxide.

The mechanisms as described above in regard to the transformation of aluminum metal into aluminum hydroxide and its

subsequent decomposition to prepare a catalyst support suggest

an idea to develop a technology based on these principles to

the preparation of a catalyst support after the application of a lower adhesive layer of aluminum on the surface of a metal strip support.

In JP9217178, 19 -08 -1997, Kanbe Yumi, and JPl 0120499, 12 -05 -1998, Kanbe Yumi, a method for preparing a thin multilayer coating is described. The coating should provide a porous metal oxide structure on which the electrically insulating material that fills the pores of the metal oxide layer is deposited.

According to the patent, during the first phase of the process, it is formed

a thin and porous metal oxide film on the substrate substrate

during the course of its hydrothermal processing in corresponding salt solutions.

Document JP9156.627, 17 -06 -1997, Nakayama Naomi, discloses a

method for preparing a multilayer oxide coating on selected substrate areas, comprising the phases of: forming an oxide coating on the substrate surface, removing the mask material, then processing in an oxidizing environment to form an oxide coating etc. The final operation is the hydrothermal processing of the coating obtained in aqueous alkaline solutions.

JP3284356, 16-12-1991, Kameyama Hideo, describes a technique for preparing a flat low temperature catalyst element, which includes the following operations. A flat substrate made of an aluminum alloy is annealed at an elevated temperature, preferably in the range of 900-1000 'C, to form a film of

oxide based on aluminum oxide on its surface. Next, the substrate undergoes hydrothermal processing in the range of

temperatures of 50-350 'C., and the metal having a catalyst activity is applied on the alumina-based catalyst support that is formed on the substrate of the flat substrate as a result of hydrothermal processing. The catalyst support that is obtained as a result of the processing

hydrothermal must be aluminum oxide with gamma modification with a

free superstore developed. A metal that has a catalyst activity can also be applied in a hydrothermal processing phase. JP2000178792, 27 -06-2000, Ishizawa Hitoshi, describes

a method for forming a titanium oxide based coating with a

free superstructure raised on a metal substrate. The method includes a phase

of preparation of the metal substrate surface, an anodizing phase

of at least one substrate substrate to form an oxide film

anodic, and a phase of application of a suspension based on aqueous solutions of metal salts and alkoxides containing dispersed metal oxide particles. After the anodizing phase, hydrothermal processing is recommended.

Document 2004058066, 2004-058066, Wei Zhiqiang, describes a method for forming a thin film metal oxide coating.

The method includes the following phases: an application phase of a sol-gel coating comprising at least one metal component on the metal substrate surface, a drying phase of said sol-gel coating, an impregnation phase of the

coating obtained in aqueous alkaline solutions containing at least one metal component, a drying phase and a hydrothermal processing phase.

The patents, according to the foregoing, show that great importance, and in some cases a fundamental importance, is given to the method of applying an aluminum coating on the support surface of

strip. A patent (RU2295588, Hinskogo A. P., March 20, 2007) discloses a process for applying aluminum powder on a surface.

A distinctive feature of the coating as described in this process is its high adhesion to the steel strip that is used as a substrate. A steel strip with a spray coating as a resulting semi-finished product has such a bond strength

high that this allows to carry out practically any operation of

mechanization, such as cutting, corrugation, drilling, etc. no delamination

or exfoliation of the sprayed layer. Summary of the invention

Using this process to spray the aluminum layer will create a coating that would combine the functions of an intermediate adhesive layer.

(on the surface adjacent to the steel strip support) and a catalytic support (on the surface of the coating as such) if it could be converted into a porous support based on aluminum oxide according to the technology as described in the foregoing.

In addition, the sequence of the application processes of the aluminum coating and its transformation into the catalyst support should be changed.

Because it is assumed that the bond strength between the coating and the

Steel substrate is so high that it will allow the semi-finished product that is obtained after spraying to be machined, it seems reasonable to include this phase

immediately after spraying, and complete the phase of

hydrothermal processing In the present case, taking into account the previous patents, the

The process should include the following successive phases:

1. Apply an adhesive layer of aluminum on the substrate of metal strip substrate 5 by the thermal spray method.

2. Mechanize (including cutting, corrugation, pertoration, etc.) to form the

catalytic element in its final form.

3. Process the resulting catalyst element in a water vapor atmosphere - air at an elevated pressure and temperature for conversion

Partial part of the supertitial portion of adhesive layer in aluminum hydroxides.

4. Thermal decomposition of the hydroxide coating obtained with its transformation into aluminum oxide to form a superlicial structure

porous

5. Apply catalysts using the impregnation method.

15 To implement the method as suggested to prepare a catalyst support, work was carried out for phases 1, 2, 3 and 4 of the process, because phase 5 is very trivial and can be carried out without preparation

preliminary.

Phase 1. 20 Apply an adhesive layer of aluminum on the substrate of a substrate

of metal strip by thermal spraying.

To apply an aluminum layer on the surface of a metal strip substrate, the following materials were used: Cold rolled steel strip made of chrome stainless steel

25 ferritic with a thickness of 40 11m and a width of 100 and 90 mm from Sandvik (Sweden). Table 2 shows the chemical composition and applicability. Table 2 Characteristics of the Sandvik OS404 cold rolled steel strip

Material Cold rolled steel strip made of chrome stainless steel

OS404 quality Chemical composition C Cr Al <0.02 20, 5.0 5.0 20, 5.5 Applicability Catalytic units for converters, heat exchangers for high temperatures

-

Aluminum powder nA-l and aluminum powder nAn-2 (rOCT 5494-95) from Volgograd Aluminum Company (BaIlKOM-nM). Basic characteristics of these materials are given in tables 3 and 4. Table 3. Basic characteristics of nA-l aluminum powder

Quality

Density Chemical composition, %

apparent,

Aluminum Elements Humidity, Area

9 f cm ',

active, residuals, max. max. superstitious

My no

My no Faith Yes Cu specific,

m 'f g

nA-l

0.96 99 0.35 0.4 0.02 0.2 -

Table 4. Basic characteristics of nAn-2 aluminum powder

Parameters

Quality

Coating power in water, cm 2 / g, min.

n An - n An -

one

2

Coating power in water, cm '/ g, min.

7000 10000

008

1.0 -

0056

- 0.3

0045

- 0.5

Flotation,%, min or

80 80

Content in residual elements,% in

Faith 0.5 0.5

weight, max.

Yes 0.4 0.4

Cu

0.05 0.05

Mn

0.01 0.01

Humidity, max.

0.2 0.2

To apply the aluminum adhesive layer, the method of

plasma spraying, which is carried out by means of a specially designed apparatus 10 in the air atmosphere using a torch of

Plasma and an original design dispenser (the description of the device and the plasma torch is given in patents RU2295588, W02008063038, W02004079035, US2001014648).

The plasma spray modes for aluminum powder and fine powder 15 as well as other process parameters are given in Table 5. Table 5. Basic parameters of the plasma spray process

Operating voltage, V

Operating current, A Device capacity, kVA Coo distance from the plasma torch nozzle, mm Plasma generation gas Powder that is being sprayed Fractional content of the mixture being sprayed

21 4

150 32.1 98 air Mixture of aluminum powder and I fine powder Max. 63) .1m

As a result of the tests, an aluminum coating was obtained

continuous of a thickness of 18 -24 11m. The chemical composition of the sprayed coating is represented by

5 means of the data of an investigation by radiography (Figure 1), which is carried out using the conventional Bragg-Brentane technique by means of

a DRON-6 radiography system that is equipped with a secondary graphite monochromator. As a source of radiation, Cu radiation was used

Ka (A = 1.541838 A). 10 Figure 1 shows an X-ray diffraction pattern of the layer of

pulverized aluminum

The bond strength between the aluminum cladding and the metal substrate was evaluated by the mechanization results of the semi product

resulting finish by visual inspection for presence

15 discontinuities in the sprayed coating (delamination,

exfoliation, etc.) Corrugation and perioration were chosen as two typical mechanization operations and aggressive enough for evaluation

of continuity Phase 2.

20 Mechanization (including cutting, corrugation, perioration, etc.) to form the catalytic element in its final form.

This phase has already been partially described in phase 1 (see above), so that an additional description of this phase seems to be superfluous. Phase 3.

5 Process the resulting catalyst element (semi-finished product)

in an atmosphere of water vapor - air at an elevated pressure and temperature for the partial conversion of the upper portion of the adhesive layer into aluminum hydroxides.

Hydrothermal processing of semi-finished support products resulting from plasma spraying and the catalyst elements (cellular structures) prepared from said support was carried out.

by means of a special device designed and manufactured to solve this

trouble. The apparatus is an autoclave press (Figure 2), which is designed to operate in the temperature and pressure range (shown in Table 6) and which includes a reaction chamber that provides a reaction space for receive semi-finished products and

catalyst elements (cellular structures) during hydrothermal processing, a gate chamber that provides a pre-placement of catalytic elements for subsequent transport to the chamber of

20 reaction, and a discharge chamber from which the processed catalyst elements are discharged. Table 6. Temperature and operating pressure ranges of the autoclave press

Parameters of

Interval Interval Duration of

operation of

temperatures, 2C pressures, atm tests,

I autoclave press

h

50 -250

10 -40 Unlimited

25 Additional device equipment includes a device (3) that provides

automatic adjustment and maintenance of process parameters

main (temperature, pressure, humidity, flow, etc.). Also, in figure 2

other elements of the autoclave press are represented, such as: valve

surplus (1), fixing bolts (2) of the cover, pressure gauge (4), 30 water vapor escape valve (5) and heating element (6). He

Processing in an autoclave press was carried out in accordance with the

modes given in table 7. Table 7. Basic modes of processing semi-finished media per m d · e 10 of an Iave autoclass press

Operating mode

T emoeratura, 'C Pressure, atm Duration, h

Mode 1

150 4 6

Mode 2

210 24 6

Mode 3

210 + 150 24 + 2 6 + 120

5 Some studies have shown that hydrothermal processing in the

all modes (1, 2 and 3) are accompanied by the transition of the layer

surface coating aluminum to aluminum oxide with modification

gamma and by the development of the coating-free surface and the formation of an optimal porosity structure.

10 The value of the relative free superstition that characterizes the development of porosity after hydrothermal processing by means of modes 2 and 3, is in the range of 60 -100 m2¡ g, which is a quite acceptable result. However, if the surface, in general, retains the microstructure

15 logical marten of the pulverized layer and, in the super-initial layer, the

presence of spherical particles of various sizes (from several microns to

tens of microns) partially deformed (flattened) and firmly joined

each other, which is a typical structure of the sprayed layer, a

completely different image when processed by mode 3. 20 In the present case, it was experimentally established that, on the pulverized layer surface, an orderly "forest" of

needle-shaped nanocrystals with a fairly uniform orientation in

relationship with the substrate. Figure 3 shows, with different magnifications, the superstitial structure of the sprayed aluminum layer after processing by means of an autoclave press according to mode 3 (see table 7).

A similar structure is formed continuously on the surface of the sprayed aluminum layer at the following temperature ranges and

of pressures (see table 8). 30 Table 8. Parametric intervals to form the coating nanostructure

during the processing of a semi-finished product sprayed from a

stage form (mode 3).

parametric fntervals to form Temperature, the coating nanostructure 'C Processing phase 1 200 -230 Processing phase 2 150 -170

Pressure, atm 22 -26 4-8 Duration, h 6-8 120 -140

Regarding the above values, indicate that the procedure phase

5 1 could also be carried out with a duration of between 6-12 hours. In the same way, the procedure phase 2 could also be carried out with a duration of between 120-160 hours. Similarly, the procedure phase 1 could also be carried out with a pressure of 20-26 atmospheres.

10 Figure 3 shows the structure of the pulverized layer surface of

aluminum after autoclave press processing one way by

stages with the decrease in processing temperature.

As the investigations of the superficial fine structure have shown

after hydrothermal processing, the increase in temperature and pressure leads to an increase in the intensity of transformation of the aluminum coating and the process progresses gradually from the

coating surface to its depth. In the present case, in the pulverized layer of pure aluminum a gradual layered transformation of metallic aluminum into a corresponding oxide and a formation of

20 specific microstructure.

Regarding the specific effect of the nanostructured "forest" of

crystals that are formed under conditions in a phased manner with the

decrease in temperature and pressure in the second phase, this is probably caused by the increase in the selectivity of the growth points

25 during the crystallization process of nanocrystals.

Claims (3)

1. A method to prepare a flexible metal-ceramic support that it has a nanocrystalline surface layer, which comprises the plasma spraying of a special aluminum-based coating on a support of metal strip with subsequent hydrothermal processing of the flexible semi-finished product, characterized in that Hydrothermal processing, which provides for optimal microstructure, nanostructure and porosity, is carried out in two phases, in the that the first phase of the processing is carried out at a pressure of 20-26 atm and temperatures of 200-230 degrees Celsius for 6-12 hours, and the second phase is carried out at a pressure of 4-8 atm and temperatures of t 50 -t 70 degrees for t20 -160 hours. 2. A method to prepare a flexible metal-ceramic support that it has a nanocrystalline surface layer according to claim 1 characterized because the first phase is carried out at a pressure of 22-26 atm and temperatures of 200-230 degrees Celsius for 6-8 hours 3. A method to prepare a flexible metal-ceramic support that it has a nanocrystalline surface layer according to claim 1 or 2 referring to a method for preparing a support characterized in that the second phase is carried out at a pressure of 4-8 atm and temperatures of 150-170 degrees for 120-140 hours.