Aluminum-titanium boron nitride coating and preparation method thereof

Abstract

The invention discloses an aluminum-titanium boron nitride coating and a preparation method thereof. The preparation method comprises the following steps: surface pretreatment; spraying to prepare a bottom layer comprising an alloy coating; and spraying and preparing a surface layer comprising boride on the bottom layer. According to the method, the surface layer is prepared through plasma spraying, the situation that in the prior art, the quality of a coating is unstable due to the fact that suspension liquid is used is avoided, the quality of the coating is improved, the bonding strength is improved, and the phenomenon that the coating locally falls off is not prone to occurring in subsequent turning machining. Automatic spraying of the coating is achieved, the efficiency is improved, the labor cost is saved, and the safety of operators is better facilitated; the coating process flow is simple, the production efficiency is high, the operation is simple, and the application prospect is wide.

Description

Technical Field

[0001] The invention belongs to the technical field of coating materials, and in particular relates to an aluminum-titanium-boron-nitride coating and a preparation method thereof. Background Art

[0002] The abradable sealing coating is an important functional coating in aircraft engines. It is used for gas path sealing and can improve the efficiency of aircraft engines and reduce fuel consumption. The aluminum-titanium-boron-nitride abradable sealing coating currently used in the inner ring of aircraft engine rectifiers is a plasma-sprayed nickel-chromium alloy base layer and a manual spray gun spraying aluminum-titanium-boron-nitride suspension to prepare the surface layer. The surface layer is an aluminum-titanium-boron-nitride suspension after the solution and powder are mixed and matured. The suspension composition fluctuates greatly, the process stability is insufficient, and the shelf life of the suspension is short, only 15 days; the manual spray gun spraying suspension preparation process requires multiple spraying and drying, and cannot be automated; secondly, the surface layer needs to be dried at room temperature for at least 12 hours, and then stepped high-temperature curing for at least 7 hours, the spraying efficiency is low, and the preparation time is long; in addition, it is difficult to control the spraying continuity when spraying with a manual spray gun, the coating structure is uneven, the coating quality is unstable, and the coating bonding strength is affected; in the subsequent turning process, the coating is prone to partial shedding, and secondary repair treatment is required, which affects the coating quality and part processing progress. During the coating preparation process, the workpiece needs to be manually sprayed, and there is a large amount of dust in the preparation environment, which has a certain impact on human health.

[0003] The patent document with the announcement number CN111250368A discloses a preparation process of polyphenyl ester sealing coating for aircraft engine casing parts, which mainly includes: preparation before spraying, cleaning and degreasing, drying, sandblasting protection with high temperature resistant tape, corundum sandblasting, plasma spraying bottom layer, plasma spraying surface layer, parts cleaning, etc. The process is used to spray polyphenyl ester coating on the inner surface area of ​​a certain engine casing part. The coating has a dense structure without oxides and cracks, and the bonding strength between the coating and the substrate is high.

[0004] The patent document with announcement number CN105441852A discloses a plasma spraying method for AlSi / BN sealing coating, and the process flow includes parts degreasing, protection before sand blasting, parts sand blasting, plasma spraying, and cleaning. The use of this process to spray AlSi / BN sealing coating on the casing of a turbomachinery compressor can reduce the gap between the tip of the rotor blade and the compressor casing, thereby improving the working efficiency of the turbomachinery compressor, thereby improving fuel utilization and reducing exhaust gas and pollutant emissions.

[0005] The process of the above patent is mainly used for polyphenylene ester sealing coating and aluminum silicon boron nitride coating, and is not suitable for solving the technical problems of low tensile bonding strength and poor coating quality stability of aluminum titanium boron nitride coating. Summary of the invention

[0006] In order to solve the above technical problems, the present invention provides an aluminum-titanium-boron-nitride coating and a preparation method thereof.

[0007] The present invention is achieved through the following technical solutions.

[0008] The invention provides an aluminum-titanium-boron-nitride coating, which comprises a bottom layer of an alloy coating and a surface layer structure comprising a boride.

[0009] A method for preparing an aluminum titanium boron nitride coating as claimed in claim 1, comprising the following steps:

[0010] S1: surface pretreatment;

[0011] S2: spraying preparation of the base layer including the alloy coating;

[0012] S3: Spraying a surface layer including a boride on the base layer.

[0013] Preferably, the surface pretreatment includes the following steps: using solution A to clean the surface of the part to be sprayed with aluminum titanium boron nitride coating, and blowing or drying it with clean compressed air after cleaning; protecting the non-sprayed surface area of ​​the part with spray protection tape; and sandblasting the surface of the part to be sprayed.

[0014] Preferably, the solution A comprises acetone and ethanol, the sand blasting pressure is 0.2-0.5 MPa, the distance between the sand blasting gun and the part is 100-150 mm, and the sand blasting angle is 45-80°.

[0015] Preferably, the bottom layer preparation includes the following steps: preparing the bottom layer by plasma spraying, preheating the parts before spraying, the preheating temperature is 80-100°C, the current is 460-500A, the hydrogen flow rate is 4-7NLPM, the argon flow rate is 30-40NLPM, and the spraying distance is 100-140mm.

[0016] Preferably, the surface layer preparation comprises the following steps: preparing the surface layer by plasma spraying, wherein the current is 400-440A, the hydrogen flow rate is 5-8NLPM, the argon flow rate is 40-50NLPM, and the spraying distance is 100-140mm.

[0017] Preferably, the bottom layer is prepared from nickel-chromium alloy powder, and the surface layer is prepared from aluminum-titanium-boron nitride composite powder.

[0018] Preferably, the powders for preparing the bottom layer and the surface layer are dried at 100-120° C. for more than 2 hours before use.

[0019] Preferably, in the steps S1-S3, the operation time interval between adjacent steps is no more than 2 hours.

[0020] Preferably, the thickness of the bottom layer is smaller than the thickness of the surface layer.

[0021] The beneficial effects of the present invention are:

[0022] The present invention adopts plasma spraying to prepare the surface layer, thereby avoiding the situation in the prior art where the suspension is used and the coating quality is unstable. The coating quality is improved, the bonding strength is improved, and the coating is not prone to local shedding during subsequent turning processing, thereby ensuring the integrity of the coating. The coating is automatically sprayed and the efficiency is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a microstructure morphology diagram of the coating prepared in Example 3 of the present invention.

[0024] Figure 2 This is a microscopic morphology of the powder of the surface layer prepared by the present invention; DETAILED DESCRIPTION

[0025] The technical solution of the present invention is further described below, but the scope of protection claimed is not limited to the description.

[0026] Embodiment 1:

[0027] A wearable and sealed aluminum-titanium-boron nitride coating comprises a bottom layer of an alloy coating and a surface layer structure comprising borides.

[0028] A method for preparing an aluminum-titanium-boron-nitride coating comprises the following steps:

[0029] S1: surface pretreatment;

[0030] S2: spraying preparation of the base layer including the alloy coating;

[0031] S3: Spraying a surface layer including a boride on the base layer.

[0032] The surface pretreatment comprises the following steps: using a brush dipped in solution A to clean the surface of the part to be sprayed with aluminum titanium boron nitride coating to remove oil stains and other dirt on the surface of the part, and blowing or air-drying with clean compressed air after cleaning; using spray protection tape to protect the non-sprayed surface area of ​​the part; and blowing sand on the surface of the part to be sprayed.

[0033] The solution A is acetone, the sand blasting pressure is 0.2 MPa, the distance between the sand blasting gun and the part is 100 mm, and the sand blasting angle is 45°, so as to ensure the surface treatment effect of the sand blasting.

[0034] When sandblasting, avoid fixing the spray gun on one part to prevent deformation or over-blowing of the part. After sandblasting, use clean compressed air to remove sand and dust on the surface of the part. Visually inspect the sandblasted surface to see if it is uniform, matte and rough, and avoid missing sandblasting. The sandblasted surface should not be touched with bare hands to prevent sweat from contacting the surface of the part and affecting the spraying effect.

[0035] The bottom layer preparation includes the following steps: using MultiCoat plasma spraying equipment to spray and prepare the bottom layer, using a spray gun to preheat the parts before spraying, the preheating temperature is 80°C, the current is 460A, the hydrogen flow rate is 4NLPM, the argon flow rate is 30NLPM, and the spraying distance is 100mm to ensure the coating thickness and material uniformity.

[0036] The surface layer preparation includes the following steps: the surface layer is prepared by spraying using MultiCoat plasma spraying equipment, wherein the current is 400A, the hydrogen flow rate is 5NLPM, the argon flow rate is 40NLPM, and the spraying distance is 100mm to ensure the coating thickness and the uniformity of the material.

[0037] like Figure 2 As shown, the bottom layer is prepared by nickel-chromium alloy powder, and the surface layer is prepared by aluminum-titanium-boron nitride composite powder.

[0038] The powders for preparing the bottom layer and the surface layer must be dried at 100°C for 3 hours before use. The powders for preparing the bottom layer and the surface layer are spread flat on a tray with a lid, placed in an oven for drying, and the dried powders are stored in the oven before use.

[0039] In the steps S1-S3, the operation time interval between adjacent steps is no more than 2 hours to avoid the adhesion of pollutants on the spraying surface, thereby affecting the coating quality.

[0040] The thickness of the bottom layer is 0.10 mm, which serves to bond the surface layer and the substrate; the thickness of the surface layer is 1.0 mm, which serves to act as an abradable seal.

[0041] Embodiment 2:

[0042] A wearable and sealed aluminum-titanium-boron nitride coating comprises a bottom layer of an alloy coating and a surface layer structure comprising borides.

[0043] A method for preparing an aluminum-titanium-boron-nitride coating comprises the following steps:

[0044] S1: surface pretreatment;

[0045] S2: spraying preparation of the base layer including the alloy coating;

[0046] S3: Spraying a surface layer including a boride on the base layer.

[0047] The surface pretreatment comprises the following steps: using absorbent cotton dipped in solution A to clean the surface of the part to be sprayed with aluminum titanium boron nitride coating to remove oil stains and other dirt on the surface of the part, and blowing or air-drying with clean compressed air after cleaning; using spray protection tape to protect the non-sprayed surface area of ​​the part; and blowing sand on the surface of the part to be sprayed.

[0048] The solution A includes acetone and ethanol, the sand blasting pressure is 0.5 MPa, the distance between the sand blasting gun and the part is 150 mm, and the sand blasting angle is 80°, so as to ensure the surface treatment effect of the sand blasting.

[0049] When sandblasting, avoid fixing the spray gun on one part to prevent deformation or over-blowing of the part. After sandblasting, use clean compressed air to remove sand and dust on the surface of the part. Visually inspect the sandblasted surface to see if it is uniform, matte and rough, and avoid missing sandblasting. The sandblasted surface should not be touched with bare hands to prevent sweat from contacting the surface of the part and affecting the spraying effect.

[0050] The bottom layer preparation includes the following steps: using MultiCoat plasma spraying equipment to spray and prepare the bottom layer, using a spray gun to preheat the parts before spraying, the preheating temperature is 100°C, the current is 500A, the hydrogen flow rate is 7NLPM, the argon flow rate is 40NLPM, and the spraying distance is 140mm to ensure the coating thickness and material uniformity.

[0051] The surface layer preparation includes the following steps: using MultiCoat plasma spraying equipment to spray the surface layer, wherein the current is 440A, the hydrogen flow rate is 8NLPM, the argon flow rate is 50NLPM, and the spraying distance is 140mm to ensure the coating thickness and material uniformity.

[0052] like Figure 2 As shown, the bottom layer is prepared by nickel-chromium alloy powder, and the surface layer is prepared by aluminum-titanium-boron nitride composite powder.

[0053] The powders for preparing the bottom layer and the surface layer must be dried at 120°C for 4 hours before use. The powders for preparing the bottom layer and the surface layer are spread flat on a tray with a lid, placed in an oven for drying, and the dried powders are stored in the oven before use.

[0054] In the steps S1-S3, the operation time interval between adjacent steps is no more than 2 hours to avoid the adhesion of pollutants on the spraying surface, thereby affecting the coating quality.

[0055] The thickness of the bottom layer is 0.20 mm, which serves to bond the surface layer and the substrate; the thickness of the surface layer is 1.2 mm, which serves to act as an abradable seal.

[0056] Embodiment 3:

[0057] A wearable and sealed aluminum-titanium-boron nitride coating comprises a bottom layer of an alloy coating and a surface layer structure comprising borides.

[0058] A method for preparing an aluminum-titanium-boron-nitride coating comprises the following steps:

[0059] S1: surface pretreatment;

[0060] S2: spraying preparation of the base layer including the alloy coating;

[0061] S3: Spraying a surface layer including a boride on the base layer.

[0062] The surface pretreatment comprises the following steps: using a brush or cotton wool dipped in solution A to clean the surface of the part to be sprayed with aluminum titanium boron nitride coating to remove oil stains and other dirt on the surface of the part, and blowing or air-drying with clean compressed air after cleaning; using spray protection tape to protect the non-sprayed surface area of ​​the part; and blowing sand on the surface of the part to be sprayed.

[0063] The solution A includes acetone and ethanol, the sand blasting pressure is 0.3 MPa, the distance between the sand blasting gun and the part is 120 mm, and the sand blasting angle is 60°, so as to ensure the surface treatment effect of the sand blasting.

[0064] When sandblasting, avoid fixing the spray gun on one part to prevent deformation or over-blowing of the part. After sandblasting, use clean compressed air to remove sand and dust on the surface of the part. Visually inspect the sandblasted surface to see if it is uniform, matte and rough, and avoid missing sandblasting. The sandblasted surface should not be touched with bare hands to prevent sweat from contacting the surface of the part and affecting the spraying effect.

[0065] The bottom layer preparation includes the following steps: using MultiCoat plasma spraying equipment to spray and prepare the bottom layer, using a spray gun to preheat the parts before spraying, the preheating temperature is 80-100°C, the current is 480A, the hydrogen flow rate is 6NLPM, the argon flow rate is 35NLPM, and the spraying distance is 120mm to ensure the coating thickness and material uniformity.

[0066] The surface layer preparation includes the following steps: the surface layer is prepared by spraying using MultiCoat plasma spraying equipment, wherein the current is 420A, the hydrogen flow rate is 6NLPM, the argon flow rate is 45NLPM, and the spraying distance is 130mm to ensure the coating thickness and material uniformity.

[0067] like Figure 2 As shown, the bottom layer is prepared by nickel-chromium alloy powder, and the surface layer is prepared by aluminum-titanium-boron nitride composite powder.

[0068] The powders for preparing the bottom layer and the surface layer must be dried at 100°C for 2.5 hours before use. The powders for preparing the bottom layer and the surface layer are spread flat on a tray with a lid, placed in an oven for drying, and the dried powders are stored in the oven before use.

[0069] In the steps S1-S3, the operation time interval between adjacent steps is no more than 2 hours to avoid the adhesion of pollutants on the spraying surface, thereby affecting the coating quality.

[0070] The bottom layer has a thickness of 0.12 mm and serves to bond the surface layer and the substrate; the surface layer has a thickness of 1.2 mm and serves to abradably seal.

[0071] The coating was sprayed on stainless steel using the method of Examples 1-3 for testing:

[0072] 1. After being kept at 300°C ± 10°C for 5 minutes, the coatings were placed in water at room temperature. After 10 cycles of testing, the coatings prepared in Examples 1-3 showed no signs of falling off or cracking.

[0073] 2. The coating was tested for performance and the results are shown in the following table.

[0074] HR15Y Tensile bond strength (MPa) Example 1 55 9 Example 2 52 9 Example 3 59 11

[0075] It can be seen from the above table that the coating prepared using the method of the present application has good abradability and mechanical properties, and the coating has high stability.

[0076] The coating preparation method provided in the present application adopts aluminum titanium boron nitride powder as the surface layer to replace the aluminum titanium boron nitride suspension in the existing process, and uses automated plasma spraying instead of manual spray gun spraying. The process is reduced from the existing "surface pretreatment → plasma spraying base layer → manual spray gun spraying surface layer → room temperature drying for at least 12 hours → step-by-step high-temperature curing for at least 7 hours" to "surface pretreatment → plasma spraying base layer → plasma spraying surface layer", which greatly improves production efficiency and reduces production costs and manual labor; secondly, by spraying powder instead of suspension, the problem of unstable coating component quality caused by large fluctuations in the suspension composition is solved. The tensile bonding strength of the coating prepared by the existing process is about 3MPa, which is easy to fall off. Figure 1 As shown, the distribution of aluminum titanium boron nitride in the coating of the present application is more uniform, and the coating has a higher tensile bonding strength.

Claims

1. An aluminum titanium boron nitride coating, characterized in that: A base layer structure comprising an alloy coating and a surface layer comprising a boride.

2. A method for preparing an aluminum titanium boron nitride coating as claimed in claim 1, characterized in that: The following steps are involved: S1: surface pretreatment; S2: spraying preparation of the base layer including the alloy coating; S3: Spraying a surface layer including a boride on the base layer.

3. The method for preparing an aluminum titanium boron nitride coating according to claim 2, characterized in that: The surface pretreatment comprises the following steps: using solution A to clean the surface of the part to be sprayed with aluminum titanium boron nitride coating, and blowing or air-drying it with clean compressed air after cleaning; using spray protection tape to protect the non-sprayed surface area of ​​the part; and blowing sand on the surface of the part to be sprayed.

4. The method for preparing an aluminum titanium boron nitride coating according to claim 3, characterized in that: The solution A includes acetone and ethanol, the sand blasting pressure is 0.2-0.5 MPa, the distance between the sand blasting gun and the part is 100-150 mm, and the sand blasting angle is 45-80°.

5. The method for preparing an aluminum titanium boron nitride coating according to claim 2, characterized in that: The bottom layer preparation comprises the following steps: preparing the bottom layer by plasma spraying, preheating the parts before spraying, the preheating temperature is 80-100°C, the current is 460-500A, the hydrogen flow rate is 4-7NLPM, the argon flow rate is 30-40NLPM, and the spraying distance is 100-140mm.

6. The method for preparing an aluminum titanium boron nitride coating according to claim 2, characterized in that: The surface layer preparation comprises the following steps: the surface layer is prepared by plasma spraying, wherein the current is 400-440A, the hydrogen flow rate is 5-8NLPM, the argon flow rate is 40-50NLPM, and the spraying distance is 100-140mm.

7. The method for preparing an aluminum titanium boron nitride coating according to claim 2, characterized in that: The bottom layer is prepared from nickel-chromium alloy powder, and the surface layer is prepared from aluminum-titanium-boron nitride composite powder.

8. The method for preparing an aluminum titanium boron nitride coating according to claim 7, characterized in that: The powders for preparing the bottom layer and the surface layer must be dried at 100-120°C for more than 2 hours before use.

9. The method for preparing an aluminum titanium boron nitride coating according to claim 2, characterized in that: In the steps S1-S3, the operation time interval between adjacent steps is no more than 2 hours.

10. The method for preparing an aluminum titanium boron nitride coating according to claim 2, characterized in that: The thickness of the bottom layer is smaller than that of the surface layer.

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