CN113981369A - Multilayer coating system and method for producing same - Google Patents

Abstract

The invention discloses a multilayer coating system deposited on the surface of a substrate and a preparation method thereof, comprising a first nano layer and a second nano layer which are alternately deposited; the first nano-layer comprises aluminum chromium boron nitride, and the second nano-layer comprises titanium diboride with a hexagonal structure with preferred orientation growth of (001) crystal planes; the texture coefficient TC of the (001) crystal face is more than or equal to 2.0, the first nano layer is provided with a region with higher boron content and a region with lower boron content, and the region with higher boron content is close to the second nano layer. The present invention is directed to a multilayer coating system to reduce the adhesive and oxidative wear of materials such as titanium alloys and nickel-base superalloys during processing.

Description

Multilayer coating system and method for producing same

Technical Field

The invention belongs to the field of surface protective coatings, and particularly relates to a multilayer coating system and a preparation method thereof.

Background

Superalloys are generally classified into nickel-based superalloys, cobalt-based superalloys, iron-based superalloys, and the like. Among them, the nickel-based superalloy has excellent high-temperature strength, good oxidation resistance, thermal corrosion resistance, good fatigue property, fracture toughness and other comprehensive properties, and is widely applied to the fields of aviation, aerospace, steamships, energy sources and the like. The difficult processing characteristics of the nickel-based high-temperature alloy are mainly represented by the problems of large cutting force, high cutting temperature, poor thermal conductivity, high-temperature hardness of the material, more metal compounds and hard points in the material and the like. When the nickel-based high-temperature alloy is processed, the cutting force is generally 1.5-2.0 times of that of steel, the cutting temperature is about twice of that of the steel, meanwhile, the material has low heat conductivity coefficient and poor heat conductivity, the cutting heat is concentrated on a tool nose and is not easy to dissipate heat, and the cutter is seriously subjected to diffusion wear, oxidation wear and bonding wear due to high temperature generated by cutting. The titanium alloy has small deformation coefficient during cutting, so that the sliding friction path of chips on the front tool surface is increased, and the abrasion of the tool is accelerated. The titanium alloy has small heat conductivity coefficient, and heat generated during cutting is not easy to be transferred and is concentrated in a small range near the cutting edge. The titanium alloy has small elastic modulus, and is easy to generate bending deformation under the action of radial force during processing, so that vibration is caused, the abrasion of a cutter is increased, and the precision of parts is influenced. Since titanium alloys have a strong chemical affinity for the material of the cutting tool, the cutting tool is prone to adhesive wear under conditions of high cutting temperature and large cutting force per unit area.

Transition metal boride TiB₂The coating has high hardness, high wear resistance, good self-lubricating property and excellent chemical stability, and is suitable for cutting processing of titanium alloy and aluminum alloy. TiB produced by Physical Vapor Deposition (PVD) process₂The coating has high hardness, brittleness and higher stress, so that TiB₂The bonding strength between the coating and the substrate is poor, and the coating is easy to peel off in a large area in the cutting process. TiB₂The high-temperature oxidation resistance of the coating is poor, and rutile-structured TiO can be generated by oxidation in air at 500 DEG C₂And B₂O₃. Compared with TiB, the nano composite Al-Cr-B-N coating formed by wrapping nano-crystalline Al-Cr-N grains with amorphous BNx phase₂High coating heightBetter thermal oxidation resistance and lower compressive stress, but the hardness and self-lubricating property of Al-Cr-B-N are inferior to those of TiB₂And (4) coating. The crystal plane (Faces), i.e. the plane passing through the centre of an atom in the crystal in crystallography. The orientation of the crystal plane is expressed by a crystal plane index, and the general formula of the crystal plane can be (hkl), such as (001).

Disclosure of Invention

In view of the above-mentioned drawbacks of the prior art, it is an object of the present invention to provide a multilayer coating system to reduce the adhesive and oxidative wear during the processing of titanium alloys, nickel-base superalloys and the like.

Due to TiB in the prior art₂The coating and the Al-Cr-B-N coating have different advantages and disadvantages respectively, and the advantages and the disadvantages of the two coatings have strong complementarity. Thus, the present application combines the two coatings to form Al-Cr-B-N/TiB₂The multi-layer coating can better mutually cooperate to play the Al-Cr-B-N coating and the TiB₂The coating has high bonding strength, high hardness and wear resistance, good self-lubricating property and high oxidation resistance due to the synergistic effect of the coating, and meets the cutting processing requirements of materials such as titanium alloy, nickel-based high-temperature alloy and the like.

The present disclosure provides a multilayer coating system deposited on a substrate surface, comprising: first and second nanolayers that are alternately deposited; the first nano-layer comprises aluminum chromium boron nitride, and the second nano-layer comprises titanium diboride with a hexagonal structure with preferred orientation growth of (001) crystal planes; the texture coefficient TC of the (001) crystal face is more than or equal to 2.0, the first nano layer is provided with a region with higher boron content and a region with lower boron content, and the region with higher boron content is close to the second nano layer.

Further, the texture coefficient TC is defined as follows:

in the formula: i (hkl) is the reflection intensity of the (hkl) crystal plane measured by X-ray diffraction, I₀N is the standard intensity of the diffraction reflection according to the PDF card number 35-0741The number of reflection crystal planes used in the calculation was (001), (100), (101), (002), (110), (200), (201), (112).

Further, the region with higher boron content is represented by the formula Al_aCr_bB_cN is limited; wherein, if the sum of the atomic numbers of three elements of Al, Cr and B is 1, a, B and c are the atomic number percentage of the elements Al, Cr and B respectively, a + B + c is 1, a is 1.5B-2.0B, 0.01. ltoreq. c is less than or equal to 0.40, and 0.40. ltoreq. a is less than or equal to 0.66.

Furthermore, the texture coefficient TC of the (001) crystal face is more than or equal to 5.0, and the titanium diboride grows in a columnar crystal form.

Further, the sum of the thicknesses of the first nanolayer and the second nanolayer is no greater than 500 nm.

Furthermore, the thickness ratio of the first nano layer to the second nano layer is R, and R is more than or equal to 1 and less than or equal to 3.

Further, a bonding layer is also included, the bonding layer is positioned between the substrate and the multi-layer coating, and the multi-layer coating comprises the first nano layer and the second nano layer which are alternately deposited; the bonding layer is Al_xCr_1-xN、Al_xTi_1-xOne or more of N, CrN, TiN, AlN, Cr and Ti coatings.

A method of making a multilayer coating system comprising the steps of:

s2: depositing a first nanolayer in a nitrogen-containing atmosphere by cathodic arc ion plating or magnetron sputtering techniques using at least one aluminum chromium boron target; the first nanolayer comprising aluminum chromium boron nitride having a region of higher boron content and a region of lower boron content, the region of higher boron content being adjacent to the second nanolayer;

s3: forming the second nanolayer by deposition in an argon atmosphere by a magnetron sputtering technique using at least one titanium-containing target material, the deposition process applying a first negative bias on the substrate; the second nano layer contains titanium diboride with a hexagonal structure with a (001) crystal face growing in a preferred orientation mode, and the texture coefficient TC of the (001) crystal face is more than or equal to 2.0;

s4: alternately performing steps S2 and S3 a plurality of times to form a multi-layered coating layer coated on the substrate; the multilayer coating includes the first and second nanolayers alternately deposited.

Further, the step S2 is preceded by the following steps:

s1: depositing a bonding layer on the substrate by a reactive cathodic arc ion plating technique and applying a second negative bias on the substrate during a portion of the deposition time; the bonding layer is located between the substrate and the multilayer coating.

Further, the aluminum-chromium-boron target material and the titanium-containing target material are both prepared by powder metallurgy; the absolute values of the first negative bias voltage and the second negative bias voltage are not lower than 40V.

The improvement of this application brings the following advantage:

(1) the embodiments of the present application provide a multi-layer coating system deposited on a substrate surface having a coating of Al-Cr-B-N (first nanolayer) and TiB₂A multi-layer coating composite system consisting of a coating (second nano-layer). Wherein the first nano layer mainly comprises aluminum chromium boron nitride, the second nano layer comprises titanium diboride with a (001) preferred orientation hexagonal structure, the boron content of the first nano layer is changed from low to high in a gradient manner, and a region with higher boron content of the first nano layer is adjacent to the second nano layer. Therefore, on one hand, a coherent interface is easier to form at the interface of the first nano layer and the second nano layer, and on the other hand, the stress of the coating is favorably reduced, so that the coating has higher bonding strength.

(2) Compared with the prior art, the composite multilayer coating forms Al-Cr-B-N/TiB₂The multi-layer coating can better mutually cooperate to play Al-Cr-B-N and TiB₂The synergistic effect of the coating not only has higher hardness and wear resistance, good self-lubricating property and excellent chemical stability, but also has higher high-temperature oxidation resistance and bonding strength, and the multi-layer coating composite system can obviously reduce the adhesive wear and the oxidation wear in the processing of materials such as titanium alloy, nickel-based high-temperature alloy and the like, thereby obviously improving the bonding wear and the oxidation wear in the processing of the materials such as titanium alloy, nickel-based high-temperature alloy and the likeCutting performance and service life, and meets the cutting processing requirements of materials such as titanium alloy, nickel-based high-temperature alloy and the like.

Drawings

FIG. 1 is a schematic cross-sectional view of a multilayer coating system deposited on a substrate surface according to an embodiment of the present application;

FIG. 2 is an electron micrograph of a physical fracture of a multilayer coating system deposited on a surface of a substrate according to an embodiment of the present application;

FIG. 3 is a top view of the relative positions of the target and substrate in the coating chamber during the process of making a multilayer coating system according to another embodiment of the present application;

FIG. 4 is an electron micrograph of a fracture of the Al-Cr-B-N single layer coating;

FIG. 5 is TiB₂Fracture electron micrographs of the single-layer coating;

wherein 1 is a multilayer coating, 11 is a first nano-layer, 12 is a second nano-layer, 2 is a bonding layer, 3 is a substrate, 4 is a top coating, 51 is a first target, 52 is a second target, 53 is a third target, 54 is a fourth target, 55 is a fifth target, and 56 is a sixth target.

Detailed Description

The embodiments of the present invention are described below with reference to specific embodiments, and other advantages and effects of the present invention will be easily understood by those skilled in the art from the disclosure of the present specification. The invention is capable of other and different embodiments and of being practiced or of being carried out in various ways, and its several details are capable of modification in various respects, all without departing from the spirit and scope of the present invention.

A multilayer coating system deposited on the surface of the substrate, as shown in fig. 1 and 2, comprising first and second nanolayers alternately deposited; the first nano-layer comprises aluminum chromium boron nitride, and the second nano-layer comprises titanium diboride with a hexagonal structure with preferred orientation growth of (001) crystal planes; the texture coefficient TC of the (001) crystal face is more than or equal to 2.0, the first nano layer is provided with a region with higher boron content and a region with lower boron content, and the region with higher boron content is close to the second nano layer.

EXAMPLE 1 Multi-layer coating System deposited on the surface of a substrate

The substrate is made of one or more of hard alloy, high-speed steel, metal ceramic and the like. The substrate may be a cutting or forming or stamping tool, or a part or part of a vehicle, or a part or part for the automotive industry or aerospace industry.

The first nanolayers and the second nanolayers that are alternately deposited comprise a multilayer coating.

The multilayer coating system also includes a bonding layer located between the substrate and the multilayer coating. The bonding layer is made of Al_xCr_1-xN、Al_xTi_1-xOne or more of N, CrN, TiN, AlN, Cr and Ti.

The first nanolayer is an Al-Cr-B-N nanolayer having regions with the highest boron content and regions with lower boron content. The region with the highest boron content is close to the second nano layer or combined with the second nano layer, a coherent interface is formed at the interface of the first nano layer and the second nano layer more easily, and the stress of the coating is reduced, so that the first nano layer and the second nano layer have high bonding strength. The region with the highest boron content is represented by the formula Al_aCr_bB_cN is limited; wherein, the sum of the number of the three elements Al, Cr and B is preset to be 1, then a, B and c in the formula are respectively the atomic number percentage of the elements Al, Cr and B, and a, B and c meet the following conditions: a + b + c is 1, a is 1.5 b-2.0 b, c is more than or equal to 0.01 and less than or equal to 0.40, and a is more than or equal to 0.40 and less than or equal to 0.66. For example, a, b, c are 0.5, 0.3, 0.2, respectively, or 0.45, 0.25, 0.3, respectively.

The second nano layer is TiB₂The texture coefficient TC of the (001) crystal face of the nano layer is more than or equal to 3.0 and is defined as follows:

in the formula: i (hkl) is the reflection intensity of the (hkl) crystal plane measured by X-ray diffraction, I₀The standard intensity of diffraction reflection according to the PDF card number 35-0741, and n is the reflection crystal face used in calculationThe (hkl) reflection planes used are (001), (100), (101), (002), (110), (200), (201), (112).

The ratio of the thicknesses of the first nanolayer and the second nanolayer is R, and R is 1.

The sum of the thicknesses of the first nanolayer and the second nanolayer is 500 nm.

The multilayer coating system further includes a top coat applied to the outside of the multilayer coating, the top coat being free of TiB₂And one or more of TiN, CrN, TiAlN, AlCrN, Al-Cr-B-N and the like is/are deposited on the multilayer coating.

Example 2 Multi-layer coating System deposited on the surface of a substrate

The texture coefficient TC of the (001) crystal face of the second nanometer layer is more than or equal to 5.0, and the titanium diboride forming the coating grows in a columnar crystal form. The ratio R of the thicknesses of the first and second nanolayers is equal to 3 or equal to 2, and the sum of the thicknesses of the first and second nanolayers is 300nm or 200nm or 100 nm.

Example 3, a method of making a multilayer coating system comprising the steps of:

s101, preparing a bonding layer: depositing a bonding layer on the substrate by a reactive cathodic arc ion plating technique, and applying a negative bias on the substrate for a portion of the deposition time; the bonding layer is positioned between the substrate and the multilayer coating and is made of TiN; the negative bias voltage is-40V or-60V or-80V or-100V; the matrix is WC-Co based hard alloy; negative bias: the negative electrode of a power supply is connected on the substrate and is used for attracting metal cations evaporated from a target material to deposit on the surface of the substrate, and the higher the negative bias is, the higher the movement speed of the metal cations is, the more obvious the bombardment effect on the surface of the substrate is, so that the surface of the coating has higher compressive stress and the hardness of the coating can be improved;

s102, preparing a first nano layer: the first nanolayer is deposited in a nitrogen-containing atmosphere using cathodic arc ion plating using three targets, respectively a first target Al₅₀Cr₂₅B₂₅A second target Al₆₀Cr₃₀B₁₀A third target material Al₅₀Cr₂₅B₂₅(ii) a The first nanolayer includes aluminum chromium boron nitride having a region with a higher boron content and a region with a lower boron content, the region with a higher boron content being adjacent to the second nanolayer;

s103, preparing a second nano layer: depositing a second nano layer by using a high-power pulse magnetron sputtering technology in an argon atmosphere, and applying negative bias on the substrate in the deposition process; the high-power pulse magnetron sputtering technology uses three target materials which are respectively a fourth target material TiB₂The fifth target material TiB₂A sixth target material Ti; the second nano layer contains titanium diboride with a hexagonal structure with a (001) crystal face growing in a preferred orientation mode, and the texture coefficient TC of the (001) crystal face is more than or equal to 2.0; the negative bias voltage is-40V or-60V or-80V or-100V;

s104, preparing a multilayer coating: alternately depositing a first nano-layer and a second nano-layer on the surface of the substrate by rotating the substrate and simultaneously implementing step S102 and step S103; in the coating chamber, the targets are arranged around the substrate in the following sequence according to the rotation direction of the substrate: a sixth target material Ti and a fifth target material TiB₂The fourth target material TiB₂A third target material Al₅₀Cr₂₅B₂₅A second target Al₆₀Cr₃₀B₁₀First target material Al₅₀Cr₂₅B₂₅(ii) a A top view of the relative positions of the target and substrate in the coating chamber is shown in fig. 3;

s105, preparing a top coating: the top coating is formed by deposition in nitrogen-containing atmosphere by high-power pulse magnetron sputtering technology, and the used target material is Ti or AlCr. When the target material is a Ti target, the top coating is TiN; when the target material is an AlCr target, the top coating is AlCrN.

Example 4, method of preparation of multilayer coating system, a first nanolayer was deposited using magnetron sputtering technique in step S102; depositing to form a second nano layer by using a direct current magnetron sputtering technology in the step S103; the target materials used in step S102 and step S103 are both prepared by a powder metallurgy technique.

Comparative example 1, FIG. 4 shows Al-Cr-B-N single-layer coating (target material is Al) prepared by cathodic arc ion plating technology₅₀Cr₂₅B₂₅)。

Comparative example 2, FIG. 5 is a TiB prepared by high power pulse magnetron sputtering technique₂And (4) single-layer coating.

Comparative experiment

(1) Table 1 compares the mechanical properties of example 1, comparative example 1 and comparative example 2.

TABLE 1 comparison of mechanical properties

Coating layer	Hardness (GPa)	Bonding Strength (N)	Oxidizing at 700 deg.C for 1h to gain weight (mg)
				Example 1	38.0	75	6
Comparative example 1	35.4	82	5
				Comparative example 2	42.0	60	10

As can be seen from Table 1, substrates coated with the multi-layer coating system of example 1 were eitherThe hardness, strength and oxidation resistance of the coating are in the aspects of Al-Cr-B-N coating and TiB₂The coating is balanced, and has the advantages of two coatings, so that the coating has high bonding strength, high hardness and high oxidation resistance, and meets the cutting processing requirements of materials such as titanium alloy, nickel-based high-temperature alloy and the like.

The hardness was measured as follows

Polishing the surface of the substrate into a mirror surface, performing opposite grinding on the surface of the coating for 20 seconds by using a bearing steel ball with the diameter of 20mm after the coating is deposited, and adding a diamond grinding agent during grinding. The hardness of the coating at the grinding mark was then tested (amplified by 100 times) using a nano indenter model TTX-NHT2 (austria anappe), the indenter was a diamond Berkovich indenter (Berkovich), the maximum load was 20mN, the loading rate was 40mN/min, the unloading rate was 40mN/min, the dwell time was 5 seconds, and in order to eliminate the influence of the matrix on the hardness, the penetration depth was 1/10 which was less than the total thickness of the coating. The hardness was measured at 20 different points in total and the average was taken as the hardness of the coating.

The binding strength was measured as follows

The bond strength of the coating to the substrate was measured using a REVETEST scratch tester manufactured by CSM of Switzerland. The scratch test method is to slide a hemispherical diamond indenter with a diameter of about 200 microns on the surface of the coating, continuously increasing the vertical load L through an automatic loading mechanism in the process, when L reaches its critical load Lc, the coating and the substrate begin to peel off, the critical load Lc of the interface between the coating and the substrate, i.e. the minimum load required for the indenter to completely scratch through the coating and continuously peel it off from the substrate; meanwhile, the friction force F between the pressure head and the coating and the substrate correspondingly changes. At the moment, the coating can generate acoustic emission, an acoustic emission signal, the load variation and the tangential force variation during scratching are obtained through a sensor, the acoustic emission signal, the load variation and the tangential force variation are amplified and input into a computer, a measurement result is drawn into a graph through A/D conversion, an acoustic emission peak is correspondingly obtained at a critical load value Lc on an acoustic emission signal-load curve, and the critical load Lc is a criterion of the bonding strength of the coating and the matrix. The test parameters are: linear loading, loading load 200N, loading rate 99N/min, scratch speed 5mm/min, scratch length 5 mm.

The oxidative weight gain was tested as follows

The sample is placed in a muffle furnace and heated to 700 ℃ under the air atmosphere, the temperature is kept for 1h, and then the sample is taken out and cooled to the room temperature in the air. And weighing the weight of the sample before and after oxidation by adopting a high-precision electronic balance with the precision of 0.1mg, and calculating the oxidation weight gain of the sample.

(2) Comparison of milled titanium alloys

The name of the workpiece: blade

Workpiece material: ti6Al4V

The model of the blade: RPHT1204M8E-MM3

Cutting conditions are as follows: cutting speed of 30m/min, cutting depth of 1.5mm, feeding of 0.15mm, and wet cutting.

The cutting life and flank wear are shown in table 2, and the flank wear of the blade is measured by an OLYMPUSSZ61 optical super depth of field microscope with a graduated scale.

TABLE 2 milling titanium alloy Ti6Al4V comparison

Coating layer	Cutting life (min)	Flank wear (mm)
			Example 1	10	0.25
Comparative example 1	6	0.32
			Comparative example 2	5	0.28

(3) Milling superalloy comparison

The name of the workpiece: flame device

Workpiece material: GH7192

The model of the blade: RPHT1204M8E-MM3

Cutting conditions are as follows: cutting speed 35m/min, cutting depth 1.5mm, feeding 0.15mm, wet cutting.

The cutting life and flank wear are shown in Table 3.

TABLE 3 milling superalloy GH7192 comparison

Coating layer	Cutting life (min)	Flank wear (mm)
			Example 1	30	0.31
Comparative example 1	22	0.32
			Comparative example 2	20	0.29

As can be seen from tables 2 and 3, compared to coating only Al-Cr-B-N coating or TiB₂Coated cutting toolThe tool coated with the multi-layer coating system of example 1, whether cutting titanium alloy or cutting high-temperature alloy, has less flank wear after cutting and longer service life.

The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are included in the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

Claims (9)

1. A multilayer coating system deposited on a surface of a substrate, comprising first and second nanolayers alternately deposited; the first nano-layer comprises aluminum chromium boron nitride, and the second nano-layer comprises titanium diboride with a hexagonal structure with preferred orientation growth of (001) crystal planes; the texture coefficient TC of the (001) crystal face is more than or equal to 2.0, the first nano layer is provided with a region with higher boron content and a region with lower boron content, and the region with higher boron content is close to the second nano layer.

2. The multilayer coating system deposited on the surface of the substrate according to claim 1, wherein the texture coefficient TC is defined as follows:

in the formula: i (hkl) is the reflection intensity of the (hkl) crystal plane measured by X-ray diffraction, I₀For the standard intensity of diffraction reflection according to the PDF card number 35-0741, n is the number of reflection crystal planes used in the calculation, and the (hkl) reflection crystal planes used are (001), (100), (101), (002), (110), (200), (201), (112).

3. The multilayer coating system deposited on the substrate surface according to claim 1 or 2, wherein the texture coefficient TC of the (001) crystal plane is not less than 5.0 and the titanium diboride grows in a columnar crystal form.

4. The multi-layer coating system deposited on a substrate surface of claim 1, wherein a sum of the thicknesses of the first and second nanolayers is no greater than 500 nm.

5. The multi-layer coating system deposited on the surface of the substrate of claim 4, wherein the ratio of the thickness of the first nanolayer and the second nanolayer is R, 1 ≦ R ≦ 3.

6. The multi-layer coating system deposited on the surface of the substrate of claim 1, further comprising a bonding layer between the substrate and the multi-layer coating, the multi-layer coating comprising the first and second nanolayers alternately deposited; the bonding layer is Al_xCr_1-xN、Al_xTi_1-xOne or more of N, CrN, TiN, AlN, Cr and Ti coatings.

7. A method for producing a multilayer coating system, comprising the steps of:

s2: depositing a first nanolayer in a nitrogen-containing atmosphere by cathodic arc ion plating or magnetron sputtering techniques using at least one aluminum chromium boron target; the first nanolayer comprising aluminum chromium boron nitride having a region of higher boron content and a region of lower boron content, the region of higher boron content being adjacent to the second nanolayer;

s3: forming the second nanolayer by deposition in an argon atmosphere by a magnetron sputtering technique using at least one titanium-containing target material, the deposition process applying a first negative bias on the substrate; the second nano layer contains titanium diboride with a hexagonal structure with a (001) crystal face growing in a preferred orientation mode, and the texture coefficient TC of the (001) crystal face is more than or equal to 2.0;

s4: alternately performing steps S2 and S3 a plurality of times to form a multi-layered coating layer coated on the substrate; the multilayer coating includes the first and second nanolayers alternately deposited.

8. The method of claim 7, wherein the step S2 is preceded by the steps of:

s1: depositing a bonding layer on the substrate by a reactive cathodic arc ion plating technique and applying a second negative bias on the substrate during a portion of the deposition time; the bonding layer is located between the substrate and the multilayer coating.

9. The method of claim 7 or 8, wherein the aluminum-chromium-boron target and the titanium-containing target are both powder metallurgically prepared targets; the absolute values of the first negative bias voltage and the second negative bias voltage are not lower than 40V.

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