A single-layer short-process wear-resistant coating material and its preparation method and application

Abstract

The present invention provides a single-layer short-process wear-resistant coating material and its preparation method and application, belonging to the field of thermal spraying technology. The wear-resistant coating is a single-layer structure, and the coating material is mainly composed of 20-40wt% NiAl and the balance Al2O3-TiO2, and the NiAl is nickel-coated aluminum powder. The coating material of the present invention prepares the NiAl component by a chemical coating process, and the particles are nearly spherical and have a core-shell coated structure, and the particle size is controlled at 53-106μm; the Al2O3-TiO2 component is prepared by a melting and crushing process, and the particles are irregular and sharp, and the particle size is controlled at 15-53μm; the NiAl / Al2O3-TiO2 composite powder is prepared by double motion mixing, and the powder is evenly dispersed. The wear-resistant coating is directly prepared on a high-temperature alloy sample by an atmospheric plasma spraying process. The bonding phase in the coating is evenly distributed, the coating has high hardness, good wear resistance, and the working temperature can reach 700°C. It can be used for the wear-resistant coating on the rotor grate of an aeroengine to achieve air path sealing. The preparation method is simple, has a short process flow, controllable precision, and high production efficiency, and is suitable for industrial spraying production.

Description

Technical Field

[0001] The invention relates to the technical field of thermal spraying wear-resistant coatings, and in particular to a single-layer short-process wear-resistant coating material and a preparation method and application thereof. Background Art

[0002] The comb seal is an important air path dynamic sealing structure in aircraft engines. It has a simple structure and good sealing effect. The core is to control the operating clearance between the comb teeth and the honeycomb to a minimum, reduce fluid leakage and thus improve engine efficiency.

[0003] Wear-resistant sealing coating, applied on the comb rotor, is a functional protective coating used to control the dynamic clearance of the comb sealing structure of aircraft engines. As a large curvature part, the comb disc is designed to minimize the running clearance with the honeycomb. During engine operation, it is subjected to temperatures of 650°C and linear speeds of 240m / s. Mechanical surge, thermal expansion and rotational centrifugal force will cause the comb teeth and the honeycomb to collide, impact and scrape. As a thin-walled part, the tip of the comb teeth is easily deformed by wear, resulting in increased gaps, increased airflow leakage, and reduced sealing effect. High-temperature wear will also cause the generation and expansion of fatigue cracks in the comb teeth, which may cause the comb disc to break and affect the safety of the entire machine in severe cases.

[0004] In order to solve this problem, one of the main measures taken is to apply a wear-resistant sealing coating on the comb ring. When the rotor-stator gap narrows and rotational friction occurs during engine operation, it can protect the comb teeth from damage and provide a good gas path seal. The coating is required to have high hardness, high bonding strength, high temperature resistance and oxidation resistance. The coating hardness is significantly higher than that of the stator honeycomb bushing. The tooth tips coated with the coating rotate at high speed to cut grooves on the metal honeycomb without wearing the tooth tips. The strong damping formed can prevent gas leakage and achieve gas path sealing to ensure the overall efficiency of the engine.

[0005] At present, there are more than 15 kinds of sealing grate parts in a single engine, and most of the sealing grate parts are made of Al 2 O 3 -3TiO 2 As a wear-resistant sealing coating, the coating has high hardness and stable chemical properties; however, the ceramic coating is highly brittle, has poor thermal expansion matching with the metal substrate, and has insufficient coating bonding strength. 2 O 3 -3TiO 2 Spraying a Ni5Al bonding layer between the coating and the substrate increases the number of coating spraying processes, increases the difficulty of thickness control, and reduces the coating production efficiency. At the same time, the coating will crack and fall off under the alternating high temperature stress, causing uneven wear and damage to the grate teeth. The sealing grate teeth must be non-destructively tested and repaired and maintained irregularly, affecting the efficiency and safety of the engine. Summary of the invention

[0006] In order to solve the above problems, the present invention provides a single-layer short-process wear-resistant coating material, which is composed of Ni-Al components and Al 2 O 3 -TiO 2 Component composition.

[0007] Furthermore, the Ni-Al component and Al 2 O 3 -TiO 2 The mass percentage of the components is: Ni-Al component 20% to 40%, the balance is Al 2 O 3 -TiO 2 .

[0008] Furthermore, the ratio of Ni to Al in the Ni-Al component is 80%:20% based on the mass percentage of the powder.

[0009] Furthermore, the Ni-Al component powder is prepared by a chemical coating process, the sphericity of the core aluminum powder is higher than 80%, and the particle size of the core aluminum powder is 37-83 μm.

[0010] Furthermore, the Ni-Al component particles are nearly spherical in shape and have a core-shell structure, with a particle size of 53 to 106 μm.

[0011] Furthermore, the Al 2 O 3 -TiO 2 The components are calculated by weight percentage of powder, consisting of TiO 2 :2.0%~4.0%;SiO 2 :0~1.5%;Fe 2 O 3 :0~1.0%; the balance is Al 2 O 3 composition.

[0012] Furthermore, the Al 2 O 3 -TiO 2 The component powders are prepared by a melting and crushing process, and the particles are irregular and sharp-edged, with a particle size of 15 to 53 μm.

[0013] The present invention also provides a method for preparing the above-mentioned single-layer short-process wear-resistant coating material, which is prepared by a double-motion mixing process, controlling the charging volume ratio to 35% to 75%, the barrel speed to 10 to 30 r / min, the spiral blade speed to 20 to 60 r / min, and the mixing time to 2 to 6 hours.

[0014] The present invention also provides a method for preparing a single-layer short-process wear-resistant coating, comprising the following steps:

[0015] (1) Sample surface cleaning: The sample is ultrasonically cleaned in acetone for 2 to 6 minutes, then cleaned in ethanol for 1 to 3 minutes, and then taken out and dried;

[0016] (2) Sample edge protection: Wrap the non-sprayed area of ​​the sample surface with high-temperature tape and make it fit tightly;

[0017] (3) Sandblasting roughening of samples: The samples are sandblasted roughened using a sandblasting machine. The sandblasting material is white corundum with a mesh size of about 150 and the sandblasting pressure is 0.5-1.0 MPa.

[0018] (4) Sample installation: The sample is fixed on the fixture to ensure that it will not fall off during rotation;

[0019] (5) Plasma spraying: control the argon flow rate to 50-75 SCFH, the hydrogen flow rate to 12-20 SCFH, the powder feeding nitrogen flow rate to 3-7 SCFH, the current to 450-550 A, the powder feeding rate to 40-70 g / min, the spray distance to 100-150 mm, the gun travel rate to 6-15 mm / s, and the overall spraying thickness to be controlled to be about 300 μm;

[0020] (6) Post-processing: remove burrs and other defects on the surface and edges of the sample, and check the appearance quality of the coating.

[0021] The present invention has the following beneficial effects:

[0022] The wear-resistant coating provided by the present invention partially replaces Al by adding NiAl components. 2 O 3 -TiO 2 Component, Al 2 O 3 -TiO 2 The components can maintain the high hardness of the coating and have excellent high temperature oxidation resistance and wear resistance; the NiAl component undergoes a self-bonding exothermic reaction during spraying and is evenly distributed to bond and support Al 2 O 3 -TiO 2 The components improve the bonding strength, toughness and density of the coating, and prevent the peeling of the aluminum oxide abrasive in the coating and the peeling of the coating. The hardness of the wear-resistant coating is in the range of HR15N80-95, which is much higher than the hardness of the grinding honeycomb; after process optimization, the bonding strength is in the range of 45-60MPa, which is much higher than that of "Ni5Al+Al 2 O 3 -3TiO 2The double-layer structure has a bonding performance increase of more than 70%. After optimization, the number of 650°C water-cooled thermal shock cycles is greater than 30 times. The coating is ground against the metal honeycomb under the simulated working conditions of 650°C, 240m / s line speed and 50μm / s feed rate, and the coating does not fall off.

[0023] The wear-resistant coating provided by the present invention adopts a single-layer structure, the coating structure is simpler and optimized, and good compatibility with the substrate is maintained, the use of an adhesive layer is avoided, and the powder replacement production process is reduced during the spraying process; the coating thickness is easier to control, and the thickness of a single spraying pass can be controlled within 0.015-0.025mm, which can effectively avoid the problem of out-of-tolerance size of special-shaped parts, save costs and improve work efficiency, and is suitable for industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0025] Figure 1 NiAl / Al 2 O 3 -TiO 2 Electron microscope image of sprayed powder, where the large white particles are NiAl and the small particles are Al 2 O 3 -3TiO 2 ;

[0026] Figure 2 NiAl / Al 2 O 3 -TiO 2 Electron micrograph of coating;

[0027] Figure 3 Electron microscope image of the coating on the surface of the grate teeth before scraping;

[0028] Figure 4 SEM image of the coating on the comb teeth surface after scraping. DETAILED DESCRIPTION

[0029] Now, various exemplary embodiments of the present invention are described in detail. The methods in the examples are conventional methods unless otherwise specified, and the reagents used are conventional commercially available reagents or reagents prepared by conventional methods unless otherwise specified. This detailed description should not be considered as a limitation of the present invention, but should be understood as a more detailed description of certain aspects, features and embodiments of the present invention.

[0030] It should be understood that the terms described in the present invention are only for describing a particular embodiment and are not intended to limit the present invention. In addition, for the numerical range in the present invention, it should be understood that each intermediate value between the upper and lower limits of the scope is also specifically disclosed. The intermediate value in any stated value or stated range, and each smaller range between any other stated value or intermediate value in the described range is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded in the scope.

[0031] Unless otherwise indicated, all technical and scientific terms used herein have the same meanings as those generally understood by those skilled in the art. Although the present invention describes only preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of a conflict with any incorporated document, the content of this specification shall prevail.

[0032] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments of the present invention description without departing from the scope or spirit of the present invention. Other embodiments derived from the present invention description will be apparent to those skilled in the art. The present invention description and examples are exemplary only.

[0033] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0034] Example 1

[0035] A single-layer short-process wear-resistant coating is provided, and the preparation steps are as follows:

[0036] (1) Preparation of NiAl component: The core aluminum powder has a sphericity of 83% and a particle size of 37 to 83 μm. A NiAl component powder with a particle size of 53 to 106 μm and a nearly spherical core-shell coating structure is prepared by chemical coating method, with a mass ratio of Ni / Al=80.2 / 19.6.

[0037] (2)Al 2 O 3 -TiO 2 Component preparation: The molten crushing process is adopted, the particles are irregular and sharp, and the particle size after air flow classification is between 15 and 53 μm.

[0038] (3)NiAl / Al 2 O 3 -TiO 2Composite powder preparation: Al2O3-TiO2 and NiAl components were loaded into the barrel of a double motion mixer at a mass ratio of 70:30, with a loading volume ratio of 65%, a barrel speed of 15r / min, a spiral blade speed of 32r / min, and a mixing time of 3h. The "gravity diffusion + shear stirring" superposition mixing was used to obtain an efficient, fine and uniformly mixed NiAl / Al 2 O 3 -TiO 2 Spray powder, such as Figure 1 shown.

[0039] (4) Preparation of wear-resistant coating

[0040] 1) Sample surface cleaning: The sample was ultrasonically cleaned in acetone for 4 minutes, then cleaned in ethanol for 3 minutes, and then taken out and dried.

[0041] 2) Sample edge protection: Wrap the non-sprayed area of ​​the sample surface with high-temperature tape and fit it tightly.

[0042] 3) Sandblasting roughening of samples: The samples were sandblasted roughened using a sandblasting machine. The sandblasting material was 150 mesh white corundum and the sandblasting pressure was 1.0 MPa.

[0043] 4) Sample installation: Fix the sample on the fixture to ensure that it will not fall off during rotation.

[0044] 5) Plasma spraying: using the NiAl / Al prepared in step (3) 2 O 3 -TiO 2 Composite powder; specific process parameters are: argon flow rate 68.0SCFH, hydrogen flow rate 16.0SCFH, powder feeding nitrogen flow rate 4.0SCFH, current 515A, powder feeding rate 65.0g / min, spray distance 150mm, gun travel rate 7mm / s, and the overall spraying thickness is controlled to be about 240μm.

[0045] 6) Post-processing: remove burrs and other defects on the surface and edges of the sample, and check the appearance quality of the coating.

[0046] (5) Coating performance test: The coating microstructure, hardness, bonding strength, thermal shock resistance and high-temperature and high-speed grinding and scraping performance are tested; the coating microstructure is as follows: Figure 2 As shown in the figure, the microscopic morphology of the coating surface before and after comb scraping under the simulated working conditions of 650℃ and line speed of 240m / s is as follows Figure 3 and Figure 4 As shown in the figure, after scraping, the coating surface adheres to honeycomb grinding debris, and the coating does not peel off. The component design of the coating material and the partial properties of the coating are shown in Table 1.

[0047] Table 1 Component design of coating materials and partial properties of coatings

[0048]

[0049] Example 2

[0050] A single-layer short-process wear-resistant coating is provided, and the preparation steps are as follows:

[0051] (1) Preparation of NiAl component: The core aluminum powder has a sphericity of 86% and a particle size of 37 to 83 μm. A NiAl component powder with a particle size of 53 to 106 μm and a nearly spherical core-shell coating structure is prepared by chemical coating method, and the mass ratio Ni / Al is 79.5 / 20.1.

[0052] (2)Al 2 O 3 -TiO 2 Component preparation: The molten crushing process is adopted, the particles are irregular and sharp, and the particle size after air flow classification is between 15 and 53 μm.

[0053] (3)NiAl / Al 2 O 3 -TiO 2 Composite powder preparation: Al 2 O 3 -TiO 2 The NiAl and NiAl components were loaded into the barrel of the double motion mixer, with a loading volume ratio of 60%, a barrel speed of 16r / min, a spiral blade speed of 30r / min, and a mixing time of 3h. The "gravity diffusion + shear stirring" superposition mixing was used to obtain an efficient, fine and uniformly mixed NiAl / Al 2 O 3 -TiO 2 Spray powder.

[0054] (4) Preparation of wear-resistant coating

[0055] 1) Sample surface cleaning: The sample was ultrasonically cleaned in acetone for 4 minutes, then cleaned in ethanol for 3 minutes, and then taken out and dried.

[0056] 2) Sample edge protection: Wrap the non-sprayed area of ​​the sample surface with high-temperature tape and fit it tightly.

[0057] 3) Sandblasting roughening of samples: The samples were sandblasted roughened using a sandblasting machine. The sandblasting material was 150 mesh white corundum and the sandblasting pressure was 1.0 MPa.

[0058] 4) Sample installation: Fix the sample on the fixture to ensure that it will not fall off during rotation.

[0059] 5) Plasma spraying: using the NiAl / Al prepared in step (3)2 O 3 -TiO 2 Composite powder; the specific process parameters are: argon flow rate 68.0SCFH, hydrogen flow rate 16.0SCFH, powder feeding nitrogen flow rate 4.0SCFH, current 510A, powder feeding rate 67.0g / min, spray distance 130mm, gun travel rate 7mm / s, and the overall spraying thickness is controlled to be about 240μm.

[0060] 6) Post-processing: remove burrs and other defects on the surface and edges of the sample, and check the appearance quality of the coating.

[0061] (5) Coating performance test: The hardness, bonding strength, thermal shock resistance and high-temperature and high-speed grinding and scraping performance of the coating were tested; the component design of the coating material and the coating performance are shown in Table 2.

[0062] Table 2 Component design and coating properties of coating materials

[0063]

[0064] The embodiments described above are only descriptions of the preferred modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A single-layer short-process wear-resistant coating material, characterized in that: It is composed of Ni-Al component and Al2O3-TiO2 component; the Ni-Al component accounts for 20% to 40% of the total weight by weight, and the balance is Al2O3-TiO2; the components in the Al2O3-TiO2 component are calculated by powder weight percentage, including TiO2: 2.0% to 4.0%; SiO2: 0 to 1.5%; Fe2O3: 0 to 1.0%; and the balance is Al2O3.

2. The single-layer short-process wear-resistant coating material according to claim 1, characterized in that: The ratio of Ni to Al in the Ni-Al component is 80%:20% based on the mass percentage of the powder.

3. The single-layer short-process wear-resistant coating material according to claim 1, characterized in that: The Ni-Al component powder is prepared by a chemical coating process, the sphericity of the core aluminum powder is higher than 80%, and the particle size of the core aluminum powder is 37-83 μm.

4. The single-layer short-process wear-resistant coating material according to claim 1, characterized in that: The Ni-Al component particles are nearly spherical in shape and have a core-shell structure, with a particle size of 53 to 106 μm.

5. The single-layer short-process wear-resistant coating material according to claim 1, characterized in that: The Al2O3-TiO2 component powder is prepared by a melting and crushing process, and the particles are irregular and sharp-edged, with a particle size of 15 to 53 μm.

6. A method for preparing a single-layer short-process wear-resistant coating material according to any one of claims 1 to 5, characterized in that: The double motion mixing process is adopted for preparation, and the volume ratio of the charge is controlled at 35% to 75%, the barrel speed is 10 to 30 r / min, the spiral blade speed is 20 to 60 r / min, and the mixing time is 2 to 6 hours.

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