High-temperature easy-to-wear ceramic coating for outer ring of aircraft engine turbine and preparation method of high-temperature easy-to-wear ceramic coating

Abstract

The invention discloses a high-temperature easy-to-wear ceramic coating for an outer ring of a turbine of an aero-engine and a preparation method, the coating comprises a metal bonding layer and a ceramic surface layer which are formed on the surface of the outer ring of the turbine of the aero-engine from inside to outside, and the porosity of the ceramic surface layer is increased in a gradient mode from inside to outside. The method comprises the following steps: (1) spraying a metal bonding layer on the working surface of an outer ring block by adopting a low-pressure plasma spraying process; and (2) an atmosphere plasma spraying process is adopted, a ceramic surface layer continues to be sprayed on the metal bonding layer, the problems that the bonding strength of the coating and the outer ring block is enough, and the blade tip needs to be prevented from being abraded are solved, and the final design requirement is met.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of aerospace materials, in particular to an aero-engine wear-resistant coating and a preparation method thereof. BACKGROUND

[0002] The high-pressure turbine rotor blade and the turbine outer ring are core hot end parts of an aero-engine. The turbine outer ring block assembled on the inner wall of the turbine casing is opposite to the rotor blade tip, and jointly forms a turbine tip gap. For details, refer to the specification of the aero-engine high-pressure turbine part with a controllable tip gap and the aero-engine in CN116291762A. Figure 2 .

[0003] The size of the aero-engine high-pressure turbine rotor tip gap significantly affects the performance of the engine. The ratio of the tip gap to the blade height increases by 1%, and the turbine efficiency decreases by about 1.5% and the fuel consumption rate increases by about 3%. In order to pursue the smallest tip gap in a stable working state, it is difficult to avoid the intermittent scraping of the tip and the outer ring in the transition state of the engine. Since it is in a super-high temperature (more than 1200 DEG C) gas environment, high-speed (hundreds of meters / second) collision and grinding occur between the rotor blade and the outer ring. Not only is the temperature very high, but the impact force is also very large, which not only damages the turbine blade, but also causes significant whole machine vibration problems. The technical requirements of the engine for the turbine outer ring are: 1. Reduce the duration of collision and grinding as much as possible and the impact force generated by collision and grinding. The working surface of the outer ring should have easy abrasion; 2. When collision and grinding occur, only the collision and grinding area of the outer ring is scraped off, and the overall structure of the outer ring remains relatively complete; 3. The working surface of the outer ring is exposed to high-temperature gas, and it is required to have high temperature resistance.

[0004] In the prior art, there are two methods to meet the above requirements in engineering: One method is to spray a thick MCrAlY easy-to-abrasion coating on the outer ring block. During work, the coating is adjacent to the rotor blade tip, and the easy-to-abrasion coating is mainly abraded when collision and grinding occur. The blade tip remains intact, which can reduce the impact and wear on the rotor blade and significantly reduce the whole machine vibration caused thereby. At the same time, the collision and grinding form a new outer ring surface, which is equivalent to secondary assembly processing, which is beneficial to reducing the tip gap during work and thus improving the efficiency of the part.

[0005] The other method is to process the working surface of the metal outer ring into dense comb-shaped grooves. Through the comb-shaped outer ring structure, the contact area of the outer ring and the blade tip when colliding and grinding can be reduced. When collision and grinding occur, the outer ring is equivalent to a sawtooth, which instantaneously completes the grinding of the blade tip to reduce the vibration intensity of the whole machine caused by collision and grinding.

[0006] The above two technical solutions have the following defects: The first method is to spray MCrAlY easy-wear coating on the outer ring block. The coating thickness is required to be not less than 1.0 mm in engineering to ensure sufficient combined machining allowance and secondary removal amount during wear. Meanwhile, the coating is required to be firmly combined with the outer ring block in high-temperature environment, and the coating is easy to wear but not easy to fall off during wear. The main problem is that the process cannot make the coating meet the above requirements at the same time. Either the coating is firmly combined with the outer ring block in high-temperature environment, but the hardness is very high, which causes the abnormal wear of the blade tip, and the easy-wear property of the coating does not meet the use requirement; or the hardness of the coating is very low, the easy-wear property meets the use requirement, but the adhesion strength and service life of the coating do not meet the requirement, and the MCrAlY coating falls off in bulk during use, thereby losing the function of maintaining the tip clearance. Meanwhile, the temperature resistance of the MCrAlY coating is only 1100 DEG C, and the coating will be quickly oxidized and fail when the temperature exceeds the use temperature, which also limits the use of the MCrAlY coating in more advanced engines.

[0007] The second method is to use cast high-temperature alloy for the outer ring block to improve the temperature resistance of the outer ring block, and to process the working surface of the metal outer ring into dense comb-shaped grooves, so that the combs on the outer ring quickly cut and wear off the blade tip during wear, thereby shortening the wear duration and impact force and reducing the vibration intensity of the whole machine caused by wear. However, the problem that the rotor blade is worn short and the overall tip clearance is increased after wear is not solved. SUMMARY

[0008] In view of the problems in the prior art, the application provides a high-temperature easy-wear ceramic coating for a turbine outer ring of an aero-engine, which solves the problem that the coating needs to meet the sufficient adhesion strength with the outer ring block and avoid wear of the blade tip.

[0009] The application aims to achieve the following: a high-temperature easy-wear ceramic coating for a turbine outer ring of an aero-engine, which comprises a metal adhesive layer and a ceramic surface layer formed on the surface of the turbine outer ring of the aero-engine from inside to outside, and the porosity of the ceramic surface layer increases from inside to outside.

[0010] As a further limitation of the high-temperature easy-wear ceramic coating for a turbine outer ring of an aero-engine, the metal adhesive layer is made of MCrAlY, wherein M is Ni or Co, and the ceramic surface layer is made of yttrium-stabilized zirconium oxide.

[0011] A preparation method of a high-temperature easy-wear ceramic coating for a turbine outer ring of an aero-engine, comprising the following steps: Step 1) spraying a metal adhesive layer on the working surface of the outer ring block by using a low-pressure plasma spraying process; Step 2) continuing to spray a ceramic surface layer on the metal adhesive layer by using an atmospheric plasma spraying process.

[0012] As a further limitation of the preparation method of the high-temperature easy-to-abrade ceramic coating for the turbine outer ring of an aero-engine, step 1) is specifically: Step 1-1) first use a transfer arc to sputter clean the working surface of the outer ring block; Step 1-2) preheat the workpiece using plasma jet without powder feeding; Step 1-3) use low-pressure plasma spraying process to spray a metal bonding layer on the working surface of the outer ring block; Step 1-4) place the outer ring block with the sprayed metal bonding layer in a vacuum heat treatment furnace, heat to the set temperature, stress relief treatment, then heat to the set temperature, diffusion treatment, and then cool to room temperature in the furnace to obtain an outer ring block with a metal bonding layer.

[0013] As a further limitation of the preparation method of the high-temperature easy-to-abrade ceramic coating for the turbine outer ring of an aero-engine, step 1-3) is specifically: in the low-pressure plasma spraying process, use gas-atomized MCrAlY powder with a particle size of 5.5-38 μm, start spraying at 7 Kpa, plasma gun current is 1800 A, argon flow is 110 L / min, hydrogen flow is 6 L / min, powder feeding rate is 45 g / min, gun moving speed is 50 mm / s, and spraying distance is 450 mm.

[0014] As a further limitation of the preparation method of the high-temperature easy-to-abrade ceramic coating for the turbine outer ring of an aero-engine, step 1-4) is specifically: place the outer ring block with the sprayed metal bonding layer in a vacuum heat treatment furnace with a vacuum degree higher than 10-2 pa, heat to 650 ℃ at a rate of 6 ℃ / min, stress relief treatment for 4 h, then heat to 980 ℃ at a rate of 15 ℃ / min, diffusion treatment for 8 h, and then cool to room temperature in the furnace.

[0015] As a further limitation of the preparation method of the high-temperature easy-to-abrade ceramic coating for the turbine outer ring of an aero-engine, step 2) specifically includes: in the atmospheric plasma spraying process, hollow spherical ceramic powder is fed into the ion high-temperature flame of the gun, the ceramic powder impacts and deposits on the metal bonding layer of the outer ring block in a molten or semi-molten state, forming a ceramic face layer.

[0016] As a further limitation of the preparation method of the high-temperature easy-to-abrade ceramic coating for the turbine outer ring of an aero-engine, the ceramic face layer is formed by repeatedly spraying thin layers, by gradually mixing organic pore-forming agents into the ceramic powder, the porosity of the entire ceramic face layer increases from the inside to the outside along the thickness direction, and at the same time, by increasing the powder feeding rate or reducing the current / hydrogen, the bonding strength between thin layers is controlled to change from strong to weak.

[0017] As a further limitation of the preparation method of the high-temperature easy-to-abrade ceramic coating for the turbine outer ring of an aero-engine according to the present application, the specific parameters of the atmospheric plasma spraying process in step 2) are as follows: the zirconia hollow spherical powder with a particle size of 55-63 μm is used, the flow rate is 60 seconds / 50 grams, the plasma gun current is 500 A, the argon flow rate is 40 L / min, the hydrogen flow rate is 10 L / min, the powder feeding rate is 15 g / min, the spraying gun moving speed is 50 mm / s, the spraying distance is 100 mm, and a 0.1-0.05 mm ceramic surface layer is formed by one spraying.

[0018] As a further limitation of the preparation method of the high-temperature easy-to-abrade ceramic coating for the turbine outer ring of an aero-engine according to the present application, the preparation method further comprises: Step 3) The cooling film holes are processed on the outer ring, and the cooling film holes penetrate the outer ring block body and the coating.

[0019] Compared with the prior art, the present application has the following beneficial effects: 1. The ceramic surface layer is used as the easy-to-abrade coating, the high heat resistance of the ceramic material is utilized to improve the temperature resistance of the outer ring easy-to-abrade coating, the designed ceramic easy-to-abrade coating has a double-layer structure, the bottom layer uses MCrAlY as the adhesive layer, the process uses low-pressure plasma, the surface layer uses YSZ ceramic, the spraying process uses atmospheric plasma, the mature process of the plasma thermal barrier coating of the turbine blade is borrowed to ensure the structural integrity of the easy-to-abrade ceramic coating. 2. The ceramic hollow spherical powder and the added organic pore-forming agent are used to make the porosity of the sprayed ceramic surface layer gradually decrease from the outer surface of the coating to the outer ring block body, the internal space of the ceramic close to the block body is 15%, the porosity of the ceramic surface layer close to the outer surface is 50%, the high porosity of the outer surface is utilized to form the easy-to-abrade property of the ceramic surface layer. 3. The process parameters are adjusted to make the lamination bonding strength of the ceramic surface layer gradually decrease along the thickness direction, and the bonding strength between the ceramic surface layers gradually decreases from 25 MPa close to the wall end to 10 MPa far from the wall end; the low bonding strength between the ceramic surface layers of the outer surface is utilized to form the easy-to-abrade property of the ceramic surface layer. 4. The stress relief heat treatment and the coating heat diffusion process are used to remove the thermal stress generated in the spraying process. The heat diffusion of the bottom adhesive layer increases the bonding strength between the coating and the block body, and the general bonding strength is greater than 70 MPa. BRIEF DESCRIPTION OF DRAWINGS

[0020] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description are only embodiments of the present application, and other drawings can also be obtained by those skilled in the art without any creative effort on the basis of the provided drawings.

[0021] Figure 1 A schematic diagram of the cross section of the coating prepared in the present application.

[0022] Figure 2 A schematic diagram of the coating on the bottom of the outer ring block in the present application.

[0023] Wherein, 100 is the outer ring block, 200 is the metal adhesive layer, and 300 is the ceramic surface layer. DETAILED DESCRIPTION

[0024] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of protection of the present application.

[0025] The high-pressure turbine rotor blade and the turbine outer ring are core hot end parts of an aero-engine. The turbine outer ring block 100 assembled on the inner wall of the turbine casing is opposite to the rotor blade tip and jointly forms a turbine tip clearance. The increase of the clearance will significantly reduce the turbine performance and further reduce the overall performance. In order to pursue as small a tip clearance as possible for the steady-state long-time work of the engine, the tip and the outer ring inevitably collide and grind during the state transformation of the engine. In order to not cause a significant increase of the tip clearance and reduce the impact on the rotor and the vibration of the overall machine caused thereby, the turbine outer ring is required to have high temperature resistance, excellent easy grinding property, and good structural integrity.

[0026] The turbine outer ring is a ring block structure. The top is designed to have a connecting structure so as to be suspended and assembled on the inner wall of the casing. A plurality of outer ring blocks 100 form a complete ring surface, are opposite to the rotor blade tip, and form a tip clearance. For the sake of simplicity, the schematic diagram of the outer ring block 100 only retains the rectangular ring block feature and omits the mounting and sealing details.

[0027] Embodiment 1 A high-temperature easy-to-grind ceramic coating for a turbine outer ring of an aero-engine includes a metal adhesive layer 200 and a ceramic surface layer 300 formed on the surface of the turbine outer ring of the aero-engine from inside to outside. The porosity of the ceramic surface layer 300 increases from inside to outside. The metal adhesive layer 200 is made of MCrAlY, wherein M is Ni or Co. The ceramic surface layer 300 is made of yttrium-stabilized zirconia YSZ.

[0028] Specifically, in the embodiment, the metal adhesive layer 200 is made of gas atomized NiCrAlY powder with a particle size of 5.5-38 μm and is sprayed by a low-pressure plasma spraying process; and the ceramic surface layer 300 is made of zirconia hollow spherical powder with a particle size of 55-63 μm and is sprayed by a large atmospheric plasma spraying process.

[0029] Embodiment 2 As shown in the figure, a method for preparing a high-temperature easy-to-abrade ceramic coating for a turbine outer ring of an aero-engine comprises the following steps: Figures 1-2 Step 1) Spraying a metal adhesive layer 200 on the working surface of the outer ring block 100 by a low-pressure plasma spraying process. Step 1-1) First, using a transfer arc to sputter clean the working surface of the outer ring block 100.

[0030] Step 1-2) Preheating the workpiece by a plasma jet under the condition of no powder feeding.

[0031] Specifically, the turbine outer ring that has been subjected to ultrasonic oil removal and sandblasting treatment is installed on a clamp and placed in a low-pressure plasma spraying chamber, and the oxygen / nitrogen content in the chamber is repeatedly vacuumed and filled with argon to dilute the oxygen / nitrogen content, the transfer arc electric cleaning and preheating treatment are performed on the surface to be sprayed.

[0032] It should be noted that the sputter cleaning further removes the oxide film and other contaminants to produce a highly active surface, which facilitates the metallurgical bonding between the metal adhesive layer 200 prepared subsequently and the turbine outer ring body; the preheating treatment of the workpiece by the plasma jet under the condition of no powder feeding increases the temperature of the contact between the coating and the turbine outer ring surface, reduces the stress generated by the difference in thermal expansion coefficients between the turbine outer ring body and the coating, and enhances the bonding strength between the coating and the turbine outer ring body. In the preferred embodiment of the application, the bonding strength between the coating and the substrate prepared by the above surface treatment method is >70 mpa, and the 1050℃ oxidation resistance reaches the complete oxidation resistance level.

[0033] Step 1-3) Spraying a metal adhesive layer 200 on the working surface of the outer ring block 100 by a low-pressure plasma spraying process.

[0034] Specifically: gas atomized NiCrAlY powder (or CoCrAlY powder to adapt to different materials of the outer ring) with a particle size of 5.5-38 μm is used, the spraying starts at 7Kpa, the plasma torch current is 1800A, the argon flow rate is 110L / min, the hydrogen flow rate is 6L / min, the powder feeding rate is 45g / min, the torch moving speed is 50mm / s, and the spraying distance is 450mm.

[0035] ​Step 1-4) Put the outer ring block 100 with the sprayed metal adhesive layer 200 into a vacuum heat treatment furnace, heat to the set temperature, and after stress relief treatment, heat to the set temperature again, and after diffusion treatment, cool to room temperature in the furnace to obtain the outer ring block 100 with the metal adhesive layer 200.

[0036] Specifically, the outer ring block 100 with the sprayed metal adhesive layer 200 is placed in a vacuum heat treatment furnace with a vacuum degree higher than 10-2pa, heated to 650℃ at a rate of 6℃ / min, and after stress relief treatment for 4h, heated to 980℃ at a rate of 15℃ / min, and after diffusion treatment for 8h, cooled to room temperature in the furnace.

[0037] It should be noted that the split turbine outer ring with the sprayed metal adhesive layer and after heat treatment is installed on a clamp, and the surface to be sprayed is again subjected to arc cleaning and preheating treatment.

[0038] The prior art only sprays a metal layer on the working surface of the outer ring, and the metal adhesive needs to meet the requirements of easy abrasion, high bonding strength (structural stability), and high temperature resistance. The present application uses a double-layer coating of a metal adhesive bottom layer + a ceramic surface layer 300 to replace the existing single metal layer. In steps 1-3 and 1-4, only the bonding strength of the metal adhesive layer 200 is strengthened, and the ceramic surface layer 300 is used to achieve easy abrasion and high temperature resistance. The overall process feasibility and technical maturity of the scheme are greatly increased.

[0039] Step 2) Continue to spray the ceramic surface layer 300 on the metal adhesive layer 200 using atmospheric plasma spraying process.

[0040] Specifically, zirconia hollow spherical powder with a particle size of 55-63μm is used, the flow rate is 60 seconds / 50 grams, the plasma gun current is 500A, the argon flow rate is 40L / min, the hydrogen flow rate is 10L / min, the powder feeding rate is 15g / min, the spray gun moving speed is 50mm / s, the spraying distance is 100mm, and a ceramic surface layer 300 of 0.1-0.05mm is formed by one spraying.

[0041] Without changing the above spraying process parameters, the organic pore-forming agent is gradually increased (at a rate of about 10%) in the ceramic powder for each subsequent spraying to increase the porosity of the coating; at the same time, the powder feeding rate is gradually increased, or the current / hydrogen amount is reduced, to gradually reduce the bonding strength between the coatings of each spraying; if necessary, nano technology or the addition of rare earth materials can be used to adjust the coating properties.

[0042] Increasing the powder feeding rate or reducing the current / hydrogen amount is equivalent to reducing the spray gun spraying power, which will reduce the kinetic energy of the sprayed droplets and reduce the interlayer bonding strength of the coating.

[0043] The ceramic surface layer 300 is formed by repeatedly spraying thin layers, and the porosity of the ceramic surface layer 300 is gradually increased from the inside to the outside along the thickness direction by gradually mixing organic pore-forming agents into the ceramic powder, and the bonding strength between the thin layers is controlled to be gradually weakened by increasing the spraying distance and angle.

[0044] It should be noted that the hollow spherical ceramic powder is sent into the ion high-temperature flame of the spray gun, and the ceramic powder is impacted and deposited on the metal bonding layer 200 of the outer ring block 100 in a molten or semi-molten state to form the ceramic surface layer 300. The thick ceramic surface layer 300 required by the present application is formed by repeatedly spraying thin layers, and the porosity of the ceramic surface layer 300 is gradually increased from the inside to the outside along the thickness direction by gradually mixing organic pore-forming agents into the ceramic powder, and the bonding strength between the thin layers is controlled to be gradually weakened by increasing the powder feeding rate or reducing the current / hydrogen.

[0045] Step 3) The cooling gas film holes are processed on the outer ring block, and the gas film holes penetrate the body and the coating of the outer ring block 100.

[0046] Specifically, the split turbine outer ring workpiece is fixed on a special chuck, and the gas film holes penetrating the turbine outer ring body and the ceramic coating are prepared by using a laser drilling technology.

[0047] Step 4) The split turbine outer ring is installed on the ring groove of the turbine casing by interference fit to splice into a complete ring, and is finished to the final size.

[0048] It should be noted that the side of the turbine outer ring coating is in a high-temperature gas for a long time, and in order to further improve the temperature resistance of the part, a certain number of cooling gas film holes are added on the outer ring block, the gas film holes penetrate the body and the coating of the outer ring block 100, and the cooling gas is introduced through the gas film holes to form a gas film on the outer surface of the coating of the outer ring block 100, so as to block the heat exchange of the high-temperature gas on the surface of the turbine outer ring. Reduce the temperature of the ceramic coating and the outer ring block 100. In the preferred embodiment of the application, the preferred gas film hole processing technology is laser drilling, which can simultaneously penetrate the metal matrix and the ceramic surface layer 300 of the outer ring block 100.

[0049] The bonding strength between the metal bonding coating and the outer ring block 100 base prepared in this embodiment is greater than 70Mpa, the porosity is within 0.5%, and the 1050℃ constant temperature oxidation experiment can reach the complete oxidation resistance level. The bonding strength between the ceramic surface layer 300 and the metal bonding coating is greater than 30Mpa, the temperature resistance of the ceramic surface layer 300 reaches 1250℃, the porosity gradually transitions from 15% near the wall end to 50% far from the wall end, and the bonding strength between the ceramic surface layers 300 gradually reduces from 25Mpa near the wall end to 10Mpa far from the wall end. The easy abrasiveness of the ceramic surface layer 300 is ensured.

[0050] In summary, the advantages of the present application include: 1. The ceramic coating is used as the easy-wear coating, the high heat resistance of the ceramic material is used to improve the temperature bearing capacity of the easy-wear coating of the outer ring; the designed ceramic easy-wear layer has a double-layer structure, the bottom layer uses NiCrAl as the adhesive layer, the process uses low-pressure plasma, the coating thickness is 0.02-0.05, the surface layer uses YSZ ceramic, the spraying process uses atmospheric plasma, the ceramic surface layer 300 has a thickness of 1.0-2.0 millimeters, the mature process of the plasma thermal barrier coating of the turbine blade is used to ensure the structural integrity of the easy-wear ceramic coating; 2. The ceramic hollow spherical ceramic powder and the added organic pore-forming agent are used, the porosity of the sprayed ceramic surface layer 300 gradually decreases from the outer surface of the coating to the outer ring block 100 substrate, the ceramic internal gap close to the substrate is 15%, the ceramic surface layer 300 close to the outer surface has a porosity of 50%, the high porosity of the outer surface is used to form the easy-wear property of the ceramic surface layer 300; 3. The process parameters are adjusted to gradually reduce the lamination bonding strength of the ceramic surface layer 300 along the thickness direction, the bonding strength between the ceramic surface layer 300 gradually decreases from 25 Mpa close to the wall end to 10 Mpa far from the wall end. The low bonding strength between the ceramic surface layer 300 of the outer surface is used to form the easy-wear property of the ceramic surface layer 300 4. The stress relief heat treatment and the coating heat diffusion process are used to remove the thermal stress generated in the spraying process. The heat diffusion of the bottom adhesive layer increases the bonding strength between the coating and the substrate, and the general bonding strength is greater than 70 MPa; The comprehensive properties of the ceramic coating are adjusted by using nanomaterials or adding trace elements such as rare earth elements.

[0051] The above examples are only used to help understand the method of the present application and its core idea. It should be noted that for ordinary skilled in the art, without departing from the principles of the present application, the present application can be improved and modified, and these improvements and modifications also fall within the protection scope of the claims of the present application.

Claims

1. A high temperature abradable ceramic coating for an aeroengine turbine outer ring, characterized in that, The metal adhesive layer and the ceramic surface layer are formed on the surface of the turbine outer ring of the aero-engine.

2. The high-temperature abradable ceramic coating for a turbine outer ring of an aero-engine according to claim 1, characterized in that, The metal adhesive layer is MCrAlY, wherein M is Ni or Co, and the ceramic surface layer is yttrium stabilized zirconia.

3. A method for producing a high-temperature abradable ceramic coating for a turbine outer ring of an aeroengine, characterized in that, The method comprises the following steps: Step 1: spraying the metal adhesive layer on the working surface of the outer ring block by using a low-pressure plasma spraying process; Step 2: continuously spraying the ceramic surface layer on the metal adhesive layer by using an atmospheric plasma spraying process.

4. The method for preparing a high-temperature wear-prone ceramic coating for an aero-engine turbine outer ring according to claim 3, characterized in that, Step 1 specifically comprises: Step 1-1: first, sputtering cleaning the working surface of the outer ring block by using a transferred arc; Step 1-2: preheating the workpiece by using a plasma jet under the condition of no powder feeding; Step 1-3: spraying the metal adhesive layer on the working surface of the outer ring block by using a low-pressure plasma spraying process; Step 1-4: placing the outer ring block with the sprayed metal adhesive layer in a vacuum heat treatment furnace, heating to a set temperature, and then performing stress relief treatment; again heating to a set temperature, and then performing diffusion treatment, and then cooling to room temperature in the furnace to obtain the outer ring block with the metal adhesive layer.

5. The method of claim 4, wherein the high-temperature, easily abradable ceramic coating for a turbine outer ring of an aeroengine is prepared by the steps of: Step 1-3 specifically comprises: in the low-pressure plasma spraying process, using air-atomized MCrAlY powder with a particle size of 5.5-38 μm, starting spraying at 7 Kpa, the plasma gun current is 1800 A, the argon flow rate is 110 L / min, the hydrogen flow rate is 6 L / min, the powder feeding rate is 45 g / min, the gun moving speed is 50 mm / s, and the spraying distance is 450 mm.

6. The method of claim 4, wherein the high-temperature, easily abradable ceramic coating for a turbine outer ring of an aeroengine is prepared by the steps of: Step 1-4 specifically comprises: placing the outer ring block with the sprayed metal adhesive layer in a vacuum heat treatment furnace with a vacuum degree higher than 10-2 pa, heating to 650 ℃ at a rate of 6 ℃ / min, and then performing stress relief treatment for 4 h; again heating to 980 ℃ at a rate of 15 ℃ / min, and then performing diffusion treatment for 8 h, and then cooling to room temperature in the furnace.

7. The method for preparing a high-temperature wear-resistant ceramic coating for an aero-engine turbine outer ring according to claim 3, characterized in that, Step 2 specifically comprises: in the atmospheric plasma spraying process, feeding the hollow spherical ceramic powder into the ion high-temperature flame of the gun, and the ceramic powder impacts and deposits on the metal adhesive layer of the outer ring block in a molten or semi-molten state to form the ceramic surface layer.

8. The method of claim 7, wherein the high-temperature, easily abradable ceramic coating for a turbine outer ring of an aeroengine is prepared by the steps of: The ceramic surface layer is formed by repeatedly spraying thin layers, the porosity gradient of the entire ceramic surface layer increases from inside to outside along the thickness direction by gradually mixing organic pore-forming agents into the ceramic powder, and the bonding strength between the thin layers is controlled to change from strong to weak by increasing the powder feeding rate or reducing the current / hydrogen.

9. The method for preparing a high-temperature, easily worn ceramic coating for an aero-engine turbine outer ring according to claim 7, characterized in that, In step 2, the specific parameters of the atmospheric plasma spraying process are as follows: using zirconia hollow spherical powder with a particle size of 55-63 μm, the flow rate is 60 seconds / 50 grams, the plasma gun current is 500 A, the argon flow rate is 40 L / min, the hydrogen flow rate is 10 L / min, the powder feeding rate is 15 g / min, the gun moving speed is 50 mm / s, the spraying distance is 100 mm, and one spraying forms a ceramic surface layer with a thickness of 0.1-0.05 mm.

10. The method for preparing a high-temperature, easily worn ceramic coating for an aero-engine turbine outer ring according to claim 3, characterized in that, The method further comprises the following steps: Step 3: machining cooling air film holes on the outer ring block, and the air film holes penetrate the outer ring block body and the coating.

Images