Ytterbium-doped high-temperature abradable sealing coating and preparation method thereof

Abstract

The invention discloses an ytterbium-doped high-temperature abradable sealing coating and a preparation method thereof.The coating comprises a nickel-based high-temperature alloy substrate layer, a NiCrAlY alloy transition layer and a YSZ / Yb2O3 ceramic layer which are sequentially arranged in a stacked mode, the YSZ / Yb2O3 ceramic layer comprises YSZ ceramic powder and a Yb2O3 lubricating phase, and the mass ratio of the YSZ ceramic powder to the Yb2O3 lubricating phase is (90-98): (2-10); ySZ / Yb2O3 ceramic powder is prepared through a high-temperature solid-phase reaction, then NiCrAlY alloy powder is sequentially sprayed on a nickel-based high-temperature alloy substrate to form a NiCrAlY alloy transition layer through a supersonic atmospheric plasma spraying technology, the YSZ / Yb2O3 ceramic powder is sequentially sprayed on the NiCrAlY alloy transition layer to form a YSZ / Yb2O3 ceramic layer, and the ytterbium-doped high-temperature abradable sealing coating is obtained. The coating has the characteristics of high service temperature, difficult cracking and peeling of the coating, high porosity, simple preparation process, excellent abradability and good thermal shock resistance.

Description

Technical Field

[0001] The invention belongs to the technical field of high-temperature thermal coatings, and in particular relates to an ytterbium-doped high-temperature abradable sealing coating and a preparation method thereof. Background Art

[0002] Yttrium-stabilized zirconia (YSZ) is commonly used as a thermal barrier coating and is widely used in gas turbines and aircraft engines to protect the metal substrate from direct erosion by high-temperature gases and extend the service life of the equipment. The main function of the YSZ coating is to insulate heat through its low thermal conductivity, thereby reducing the operating temperature of the metal substrate and significantly improving the thermal efficiency and reliability of turbines and engines.

[0003] In the 1980s, YSZ was gradually applied to coatings. It was also used as a wearable sealing coating to minimize the gap between the coating and the rotating blades, thereby further improving compressor efficiency and reducing fuel consumption. YSZ coatings not only insulate heat through their low thermal conductivity and reduce the operating temperature of the metal substrate, but also their wearable properties enable them to fine-tune the gap during operation to achieve the best sealing effect. It is worth noting that wearable sealing coatings are usually designed and prepared to be soft enough to protect the blades from damage in certain complex environments. However, with the increasingly harsh operating conditions of modern high thrust-to-weight ratio aircraft engines and gas turbines, traditional YSZ coatings can no longer fully meet the increasing performance requirements, such as high temperature stability, wear resistance, good thermal shock resistance and excellent corrosion resistance. Among these performance indicators, the thermal shock resistance of the coating is an important parameter for evaluating the feasibility of the application of wearable sealing coatings.

[0004] It is reported that the service life of abradable sealing coatings during thermal shock cycles is mainly affected by the coating, transition layer and base alloy structure. Studies have shown that optimizing these structures can significantly improve the thermal shock resistance and overall performance of the coating. For example, by doping other oxides in YSZ, its thermal conductivity and mechanical properties can be improved. In addition, the use of advanced spraying techniques, such as supersonic plasma spraying, can enhance the density and adhesion of the coating, thereby improving its stability and durability in high temperature environments.

[0005] Li Shu et al. (Li Shu; Wang Senyuan; Tan Haibing; Wang Jing; Zhong Yan; Zhu Changhong; Fang Yongchao; Tian Haoliang; Research on the abradability of nickel-copper / boron nitride coating in acidic salt spray corrosion environment [J]; Thermal Spraying Technology; Issue 01, 2024) used plasma spraying to prepare the coating. The bottom spray powder was nickel-aluminum and the bottom thickness was 500um; the nickel-copper / boron nitride coating was sprayed with a thickness of about 900um. Nickel copper was used as the main component of the coating, and the corrosion dense area was added. The anti-corrosion effect was obvious, but due to the densification of the structure, its abradability decreased.

[0006] Li Junchen et al. (Li Junchen, Luo Kuilin, Chen Mingxu, et al. Study on high-temperature abradability of copper-aluminum / nickel-graphite sealing coatings [J]. Thermal Spraying Technology, 2023, 15(1): 52-60.) used Metco 6C-6P flame powder spraying equipment to spray a 300um thick copper-aluminum / nickel-graphite coating. Because it uses nickel graphite as a lubricating phase, the coating scraped by the blades adheres to the blades during the wear process, further aggravating the wear of the coating. In addition, flame spraying may cause partial oxidation of the coating surface, affecting its thermal shock resistance and abrasion resistance, making the coating life relatively short. Summary of the invention

[0007] In order to solve the shortcomings of the above-mentioned prior art, the purpose of the present invention is to provide an ytterbium-doped high-temperature abradable sealing coating and a preparation method thereof, wherein YSZ / Yb2O3 ceramic powder is prepared by high-temperature solid phase reaction, and then NiCrAlY alloy powder is sprayed on a nickel-based high-temperature alloy substrate in sequence by supersonic atmospheric plasma spraying technology to form a NiCrAlY alloy transition layer, and YSZ / Yb2O3 ceramic powder is sprayed on the NiCrAlY alloy transition layer to form a YSZ / Yb2O3 ceramic layer, thereby obtaining an ytterbium-doped high-temperature abradable sealing coating, which has the characteristics of high service temperature, coating not easy to crack and peel off, high porosity, simple preparation process, excellent abradability and good thermal shock resistance.

[0008] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0009] A ytterbium-doped high-temperature abradable sealing coating comprises a nickel-based high-temperature alloy substrate layer, a NiCrAlY alloy transition layer and a YSZ / Yb2O3 ceramic layer which are stacked in sequence. The raw materials of the YSZ / Yb2O3 ceramic layer include YSZ ceramic powder and Yb2O3 lubricating phase. The mass ratio of YSZ ceramic powder:Yb2O3 lubricating phase is (90-98):(2-10).

[0010] The raw material of the NiCrAlY alloy transition layer is NiCrAlY alloy powder.

[0011] The thickness of the NiCrAlY alloy transition layer is 70-100 μm.

[0012] The thickness of the YSZ / Yb2O3 ceramic layer is not less than 300 μm.

[0013] A method for preparing an ytterbium-doped high-temperature abradable sealing coating comprises the following steps:

[0014] Step 1: Mix YSZ ceramic powder and Yb2O3 powder, ball mill and stir until the powder mixture becomes gel; dry and sinter the gel powder in sequence to obtain YSZ / Yb2O3 ceramic powder; by mass ratio, YSZ ceramic powder: Yb2O3 powder = (90-98): (2-10);

[0015] Step 2: ball-milling the YSZ / Yb2O3 ceramic powder, binder, deionized water and anhydrous ethanol obtained in step 1 to obtain a YSZ / Yb2O3 ceramic-based multiphase mixed solution; by mass ratio, YSZ / Yb2O3 ceramic powder: binder: deionized water: anhydrous ethanol = (96-106): (94-104): (15-25): (15-25); the binder is polyacrylate or polymethyl methacrylate;

[0016] Step 3: Granulate and dry the YSZ / Yb2O3 ceramic multiphase mixed solution obtained in step 2 to obtain granulated YSZ / Yb2O3 sprayable ceramic powder;

[0017] Step 4: spraying NiCrAlY alloy powder on the surface of the pretreated nickel-based high-temperature alloy substrate to form a NiCrAlY alloy transition layer;

[0018] Step 5: Spray the YSZ / Yb2O3 sprayable ceramic powder obtained in step 3 onto the NiCrAlY alloy transition layer formed in step 4 to form a YSZ / Yb2O3 ceramic layer, that is, to obtain an ytterbium-doped high-temperature abradable sealing coating.

[0019] The ball milling speed in the step 1 is 200-300r / min, and the ball milling time is 8-10h; the stirring speed is 700-1200r / min, and the stirring temperature is 180-220°C; the drying temperature is 90-105°C, and the drying time is 8-10h; the sintering conditions are to increase the temperature from room temperature to 300°C at a heating rate of 8-10°C / min, continue to increase the temperature from 300 to 950°C at a heating rate of 6-8°C / min, keep warm at 950°C for 1-1.5h, then increase the temperature to 1250°C at a heating rate of 4-6°C / min, and keep warm at 1250°C for 8-10h.

[0020] The ball milling speed in step 2 is 60-90 r / min, and the ball milling time is 4-6 h.

[0021] In step 3, a spray granulator is used for granulation and drying. The inlet temperature of the spray granulator is 300-350° C., the outlet temperature is 100-120° C., the nozzle speed is 32-36 r / min, and the speed of the peristaltic pump is 13-15 r / min.

[0022] The pretreatment process of the nickel-based high-temperature alloy substrate layer in step 4 is: grinding and cleaning the nickel-based high-temperature alloy substrate using 80 and 240 mesh sandpapers in turn, and then sandblasting aluminum oxide to obtain a nickel-based high-temperature alloy substrate with a certain roughness.

[0023] Both step 4 and step 5 are sprayed by supersonic atmospheric plasma spraying process. The spraying power used in the spraying process of step 4 and step 5 is 45-50kW, the argon flow rate is 65-70slpm, and the hydrogen flow rate is 4-7slpm. The spraying current in step 4 is 830-850A, and the voltage is 44-45V; the spraying current in step 5 is 820-840A, and the voltage is 43-44V.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] 1. Compared with pure YSZ ceramic-based abradable sealing coatings, the present invention adopts the method of adding Yb2O3 crystals to make the thermal expansion coefficients of the ceramic layer, transition layer and substrate more matched, thereby increasing the porosity, so that the ytterbium-doped high-temperature abradable sealing coating has obvious advantages in a service environment of 1200°C, and exhibits good thermal shock resistance in the same thermal shock cycle process.

[0026] 2. The present invention prepares an ytterbium-doped high-temperature abradable sealing coating by introducing Yb2O3 as a lubricating phase, thereby reducing the hardness of the coating surface, improving the abradability, and extending the service life.

[0027] 3. The present invention only needs polyacrylate or polymethyl methacrylate as a binder to complete granulation, prepares YSZ / Yb2O3 ceramic powder by high-temperature solid-phase reaction, adds deionized water and anhydrous ethanol as dispersants, and uses a spray granulator to make YSZ / Yb2O3 ceramic granulated powder, which is then sprayed to obtain an ytterbium-doped high-temperature abradable sealing coating. The entire preparation process is simple.

[0028] 4. Compared with pure YSZ ceramic-based abradable sealing coatings, the present invention adds Yb2O3 crystals during the preparation of YSZ / Yb2O3 ceramic powders, so that it serves as a lubricating phase structure in the coating after spraying. The addition of Yb2O3 during atmospheric plasma spraying affects the growth of YSZ grains and the diffusion process of grain boundaries, resulting in uneven distribution of particle size after doping, thereby increasing the porosity of the ytterbium-doped high-temperature abradable sealing coating and improving the hardness value. During the thermal shock process, the stress is relatively dispersed, and it is not easy to produce stress concentration and cause local shedding. Therefore, it has good thermal shock resistance and service life.

[0029] In summary, the present invention forms a NiCrAlY alloy transition layer and a YSZ / Yb2O3 ceramic layer in sequence on a nickel-based high-temperature alloy substrate through atmospheric plasma spraying equipment to obtain an ytterbium-doped high-temperature abradable sealing coating, which has the characteristics of excellent friction and wear performance, the coating is not easy to crack and peel off, has good thermal shock resistance, low hardness, excellent abradability and simple preparation process. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a schematic structural diagram of the ytterbium-doped high-temperature abradable sealing coating prepared by the present invention.

[0031] Figure 2 It is the SEM spectrum of the YSZ / Yb2O3 ceramic powder prepared by the present invention.

[0032] Figure 3 The YSZ / Yb2O3 sprayable ceramic powder prepared by the present invention comprises: Figure 3 (a) is at low magnification. Figure 3 (b) is at high magnification.

[0033] Figure 4 : is a SEM comparison diagram of the ytterbium-doped high-temperature abradable sealing coating prepared by the present invention and the YSZ abradable sealing coating, wherein: Figure 4 (a) is the YSZ abradable sealing coating, Figure 4 (b) Ytterbium-doped high-temperature abradable sealing coating.

[0034] Figure 5 : is a hardness comparison chart of the ytterbium-doped high-temperature abradable sealing coating prepared by the present invention and the YSZ abradable sealing coating, wherein: Figure 5 (1) Figure 5 (2) and Figure 5 (3) are at three different positions on the surface of the YSZ sample, Figure 5 (4) Figure 5 (5) and Figure 5 (6) are three different locations on the surface of the YS Z / Yb2O3 sample.

[0035] Figure 6 The three-dimensional wear scar comparison diagram of the ytterbium-doped high-temperature abradable sealing coating and the YSZ coating prepared by the present invention, wherein: Figure 6 (a) is a Ytterbium-doped high-temperature abradable sealing coating. Figure 6 (b) is the YSZ abradable sealing coating.

[0036] Figure 7 It is a two-dimensional wear scar depth curve of the ytterbium-doped high-temperature abradable sealing coating and the YSZ coating prepared by the present invention, wherein: Figure 7 (a) and Figure 7(b) The original data of the YSZ abradable sealing coating and the fitted approximate curve area diagram; Figure 7 (c) and Figure 7 (d) are the original data of the ytterbium-doped high-temperature abradable sealing coating and the fitted approximate curve area diagram.

[0037] Figure 8 : is a thermal shock comparison diagram of the ytterbium-doped high-temperature abradable sealing coating and the YSZ abradable sealing coating prepared by the present invention, wherein: Figure 8 (a) is the YSZ abradable sealing coating, Figure 8 (b) Ytterbium-doped high-temperature abradable sealing coating.

[0038] Fig. 9 This is a diagram of the thermal shock test device of the ytterbium-doped high-temperature abradable sealing coating prepared in the present invention. DETAILED DESCRIPTION

[0039] The technical solution of the present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0040] A ytterbium-doped high-temperature abradable sealing coating comprises a nickel-based high-temperature alloy substrate layer, a NiCrAlY alloy transition layer and a YSZ / Yb2O3 ceramic layer which are stacked in sequence. The raw materials of the YSZ / Yb2O3 ceramic layer include YSZ ceramic powder and Yb2O3 lubricating phase; in terms of mass ratio, YSZ ceramic powder:Yb2O3 lubricating phase=(90-98):(2-10); the raw material of the NiCrAlY alloy transition layer is NiCrAlY alloy powder.

[0041] A method for preparing an ytterbium-doped high-temperature abradable sealing coating comprises the following steps:

[0042] Step 1: Mix YSZ ceramic powder and Yb2O3 powder and ball mill them; the speed of the ball mill is in the range of 200-300r / min, and the ball milling time is 8-10h to obtain a uniform powder mixture; under the stirring condition of 700-1200r / min and the temperature is controlled at 180-220℃, continue to stir until the powder mixture becomes a gel; then put the gel mixture into an oven and dry it at a temperature of 90-105 ℃, drying time is 8-10h, to obtain a uniformly mixed powder to be sintered; the powder to be sintered is sintered in stages, wherein the temperature is raised from room temperature to 300℃ at a heating rate of 8-10℃ / min, and the temperature is further raised from 300 to 950℃ at a heating rate of 6-8℃ / min, and the temperature is kept at 950℃ for 1-1.5h, and then the temperature is raised to 1250℃ at a heating rate of 4-6℃ / min, and the temperature is kept at 1250℃ for 8-10h to obtain YSZ / Yb2O3 ceramic powder; by mass ratio, YSZ ceramic powder: Yb2O3 powder = (90-98): (2-10);

[0043] Step 2: Mix the YSZ / Yb2O3 ceramic powder prepared in step 1 with a binder, deionized water and anhydrous ethanol and perform ball milling; the ball milling speed is 60-90r / min, and the ball milling time is 4-6h; by mass ratio, YSZ / Yb2O3 ceramic powder: binder: deionized water: anhydrous ethanol = (96-106): (94-104): (15-25): (15-25), to obtain a YSZ / Yb2O3 ceramic-based multiphase mixed liquid; the binder is polyacrylate or polymethyl methacrylate;

[0044] Step 3: Granulate and dry the YSZ / Yb2O3 ceramic-based multiphase mixed liquid prepared in step 2; the inlet temperature of the spray granulator is 300-350°C, the outlet temperature is 100-120°C, the nozzle speed is 32-36r / min, and the peristaltic pump speed is 13-15r / min to obtain the granulated YSZ / Yb2O3 sprayable ceramic powder;

[0045] Step 4: Use 80 and 240 grit sandpaper to grind and clean the nickel-based high-temperature alloy substrate in turn, and then sandblast aluminum oxide to obtain a nickel-based high-temperature alloy substrate with a certain roughness;

[0046] A NiCrAlY alloy powder is sprayed on the surface of the roughened nickel-based high-temperature alloy substrate using a supersonic atmospheric plasma spraying process to form a NiCrAlY alloy transition layer; the thickness of the NiCrAlY alloy transition layer is 70-100 μm, the spraying power is 45-50 kW, the argon flow rate used in the spraying process is 65-70 slpm, the hydrogen flow rate is 4-7 slpm, the spraying current is 830-850 A, and the voltage is 44-45 V;

[0047] Step 5: Use supersonic atmospheric plasma spraying technology to spray the YSZ / Yb2O3 sprayable ceramic powder obtained in step 3 on the NiCrAlY alloy transition layer formed in step 4 to form a YSZ / Yb2O3 ceramic layer, and finally obtain an ytterbium-doped high-temperature abradable sealing coating; the spraying power is 45-50kW, the argon flow rate during spraying is 65-70slpm, the hydrogen flow rate is 4-7slpm, the spraying current is 820-840A, and the voltage is 43-44V; the thickness of the YSZ / Yb2O3 ceramic layer is not less than 300μm.

[0048] Example 1

[0049] A ytterbium-doped high-temperature abradable sealing coating comprises a nickel-based high-temperature alloy substrate layer, a NiCrAlY alloy transition layer and a YSZ / Yb2O3 ceramic layer which are stacked in sequence; the raw materials of the YSZ / Yb2O3 ceramic layer include 90g of YSZ ceramic powder and 10g of ytterbium oxide powder.

[0050] A method for preparing an ytterbium-doped high-temperature abradable sealing coating comprises the following steps:

[0051] Step 1: Mix 90g of YSZ ceramic powder and 10g of ytterbium oxide powder and ball mill them at 200r / min for 8h to obtain a uniformly mixed powder mixture; continue to stir at 700r / min and 180°C until the powder mixture becomes a gel; then dry the gel mixture at 105°C for 8h to obtain a uniformly mixed powder to be sintered; sinter the powder to be sintered in stages, wherein the temperature is increased from room temperature to 300°C at 8°C / min, and then increased to 950°C at 6°C / min, and kept at 950°C for 1h, and then increased to 1250°C at 4°C / min, and kept at 1250°C for 8h to obtain YSZ / Yb2O3 ceramic powder;

[0052] Step 2: The YSZ / Yb2O3 ceramic powder prepared in step 1 is mixed with polyacrylate, deionized water and anhydrous ethanol and ball-milled at 60 r / min for 4 h; by mass ratio, YSZ / Yb2O3 ceramic powder: polyacrylate: deionized water: anhydrous ethanol = 96:94:15:15, to obtain a YSZ / Yb2O3 ceramic-based multiphase mixed liquid;

[0053] Step 3: Granulate and dry the YSZ / Yb2O3 ceramic-based multiphase mixed liquid prepared in step 2; the inlet temperature of the spray granulator is 300°C, the outlet temperature is 100°C, the nozzle speed is 32r / min, and the peristaltic pump speed is 13r / min, to obtain the granulated YSZ / Yb2O3 sprayable ceramic powder;

[0054] Step 4: Use 80 and 240 grit sandpaper to grind and clean the nickel-based high-temperature alloy substrate in turn, and then sandblast aluminum oxide to obtain a nickel-based high-temperature alloy substrate with a certain roughness;

[0055] Using supersonic atmospheric plasma spraying technology to spray NiCrAlY alloy powder on the surface of the roughened nickel-based high-temperature alloy substrate to form a NiCrAlY alloy transition layer; the thickness of the NiCrAlY alloy transition layer is 70 μm, the spraying power is 45 kW, the argon flow rate used in the spraying process is 65 slpm, the hydrogen flow rate is 4 slpm, the spraying current is 830 A, and the voltage is 44 V;

[0056] Step 5: Use supersonic atmospheric plasma spraying technology to spray the YSZ / Yb2O3 sprayable ceramic powder obtained in step 3 on the NiCrAlY alloy transition layer formed in step 4 to form a YSZ / Yb2O3 ceramic layer, and finally obtain an ytterbium-doped high-temperature abradable sealing coating; the spraying power is 45kW, the argon flow rate during spraying is 65slpm, the hydrogen flow rate is 4slpm, the spraying current is 820A, and the voltage is 43V; the thickness of the YSZ / Yb2O3 ceramic layer is 310μm.

[0057] Example 2

[0058] A ytterbium-doped high-temperature abradable sealing coating comprises a nickel-based high-temperature alloy substrate layer, a NiCrAlY alloy transition layer and a YSZ / Yb2O3 ceramic layer which are stacked in sequence; the raw materials of the YSZ / Yb2O3 ceramic layer include 92g of YSZ ceramic powder and 8g of ytterbium oxide powder.

[0059] A method for preparing an ytterbium-doped high-temperature abradable sealing coating comprises the following steps:

[0060] Step 1: Mix 92g YSZ ceramic powder and 8g ytterbium oxide powder and ball mill them at 300r / min for 10h to obtain a uniformly mixed powder mixture; continue to stir at 1200r / min and 220°C until the powder mixture becomes a gel; then dry the gel mixture at 90°C for 10h to obtain a uniformly mixed powder to be sintered; sinter the powder to be sintered in stages, wherein the temperature is increased from room temperature to 300°C at 10°C / min, and then increased to 950°C at 8°C / min, and kept at 950°C for 1.5h, and then increased to 1250°C at 6°C / min, and kept at 1250°C for 10h to obtain YSZ / Yb2O3 ceramic powder;

[0061] Step 2: The YSZ / Yb2O3 ceramic powder prepared in step 1 is mixed with polymethyl methacrylate, deionized water and anhydrous ethanol and ball-milled at 60 r / min for 4 h; by mass ratio, YSZ / Yb2O3 ceramic powder: polymethyl methacrylate: deionized water: anhydrous ethanol = 106:104:25:25, to obtain a YSZ / Yb2O3 ceramic-based multiphase mixed liquid;

[0062] Step 3: Granulate and dry the YSZ / Yb2O3 ceramic-based multiphase mixed liquid prepared in step 2; the inlet temperature of the spray granulator is 350°C, the outlet temperature is 120°C, the nozzle speed is 36r / min, and the peristaltic pump speed is 15r / min, to obtain the granulated YSZ / Yb2O3 sprayable ceramic powder;

[0063] Step 4: Use 80 and 240 grit sandpaper to grind and clean the nickel-based high-temperature alloy substrate in turn, and then sandblast aluminum oxide to obtain a nickel-based high-temperature alloy substrate with a certain roughness;

[0064] Using supersonic atmospheric plasma spraying technology to spray NiCrAlY alloy powder on the surface of the roughened nickel-based high-temperature alloy substrate to form a NiCrAlY alloy transition layer; the thickness of the NiCrAlY alloy transition layer is 100 μm, the spraying power is 50 kW, the argon flow rate used in the spraying process is 70 slpm, the hydrogen flow rate is 7 slpm, the spraying current is 850 A, and the voltage is 45 V;

[0065] Step 5: Use supersonic atmospheric plasma spraying technology to spray the YSZ / Yb2O3 sprayable ceramic powder obtained in step 3 on the NiCrAlY alloy transition layer formed in step 4 to form a YSZ / Yb2O3 ceramic layer, and finally obtain an ytterbium-doped high-temperature abradable sealing coating; the spraying power is 50kW, the argon flow rate during spraying is 70slpm, the hydrogen flow rate is 7slpm, the spraying current is 840A, and the voltage is 44V; the thickness of the YSZ / Yb2O3 ceramic layer is 350μm.

[0066] Example 3

[0067] A ytterbium-doped high-temperature abradable sealing coating comprises a nickel-based high-temperature alloy substrate layer, a NiCrAlY alloy transition layer and a YSZ / Yb2O3 ceramic layer which are stacked in sequence; the raw materials of the YSZ / Yb2O3 ceramic layer include 94g YSZ ceramic powder and 6g ytterbium oxide powder.

[0068] A method for preparing an ytterbium-doped high-temperature abradable sealing coating comprises the following steps:

[0069] Step 1: Mix 94g YSZ ceramic powder and 6g ytterbium oxide powder and ball mill them at 250r / min for 9h to obtain a uniformly mixed powder mixture; continue stirring at 1000r / min and 200°C until the powder mixture becomes a gel; then dry the gel mixture at 95°C for 9h to obtain a uniformly mixed powder to be sintered; sinter the powder to be sintered in stages, wherein the temperature is increased from room temperature to 300°C at 9°C / min, and then increased to 950°C at 7°C / min, and kept at 950°C for 1h, and then increased to 1250°C at 5°C / min, and kept at 1250°C for 10h to obtain YSZ / Yb2O3 ceramic powder;

[0070] Step 2: The YSZ / Yb2O3 ceramic powder prepared in step 1 is mixed with polyacrylate, deionized water and anhydrous ethanol and ball-milled at 75 r / min for 5 h; by mass ratio, YSZ / Yb2O3 ceramic powder: polyacrylate: deionized water: anhydrous ethanol = 104:100:20:20, to obtain a YSZ / Yb2O3 ceramic-based multiphase mixed liquid;

[0071] Step 3: Granulate and dry the YSZ / Yb2O3 ceramic-based multiphase mixed liquid prepared in step 2; the inlet temperature of the spray granulator is 325°C, the outlet temperature is 110°C, the nozzle speed is 35r / min, and the peristaltic pump speed is 14r / min, to obtain the granulated YSZ / Yb2O3 sprayable ceramic powder;

[0072] Step 4: Use 80 and 240 grit sandpaper to grind and clean the nickel-based high-temperature alloy substrate in turn, and then sandblast aluminum oxide to obtain a nickel-based high-temperature alloy substrate with a certain roughness;

[0073] Using supersonic atmospheric plasma spraying technology to spray NiCrAlY alloy powder on the surface of the roughened nickel-based high-temperature alloy substrate to form a NiCrAlY alloy transition layer; the thickness of the NiCrAlY alloy transition layer is 85 μm, the spraying power is 50 kW, the argon flow rate used in the spraying process is 67 slpm, the hydrogen flow rate is 5 slpm, the spraying current is 840 A, and the voltage is 44 V;

[0074] Step 5: Use supersonic atmospheric plasma spraying technology to spray the YSZ / Yb2O3 sprayable ceramic powder obtained in step 3 on the NiCrAlY alloy transition layer formed in step 4 to form a YSZ / Yb2O3 ceramic layer, and finally obtain an ytterbium-doped high-temperature abradable sealing coating; the spraying power is 47kW, the argon flow rate during spraying is 67slpm, the hydrogen flow rate is 5slpm, the spraying current is 825A, and the voltage is 43V; the thickness of the YSZ / Yb2O3 ceramic layer is 320μm.

[0075] Example 4

[0076] A ytterbium-doped high-temperature abradable sealing coating comprises a nickel-based high-temperature alloy substrate layer, a NiCrAlY alloy transition layer and a YSZ / Yb2O3 ceramic layer which are stacked in sequence; the raw materials of the YSZ / Yb2O3 ceramic layer include 95g YSZ ceramic powder and 5g ytterbium oxide powder.

[0077] A method for preparing an ytterbium-doped high-temperature abradable sealing coating comprises the following steps:

[0078] Step 1: Mix 95g of YSZ ceramic powder and 5g of ytterbium oxide powder and ball mill them at 270r / min for 10h to obtain a uniformly mixed powder mixture; continue to stir at 1100r / min and 210°C until the powder mixture becomes a gel; then dry the gel mixture at 100°C for 10h to obtain a uniformly mixed powder to be sintered; sinter the powder to be sintered in stages, wherein the temperature is increased from room temperature to 300°C at 10°C / min, and then increased to 950°C at 7°C / min, and kept at 950°C for 1.5h, and then increased to 1250°C at 4°C / min, and kept at 1250°C for 10h to obtain YSZ / Yb2O3 ceramic powder;

[0079] Step 2: The YSZ / Yb2O3 ceramic powder prepared in step 1 is mixed with polyacrylate, deionized water and anhydrous ethanol and ball-milled at 80 r / min for 6 hours; by mass ratio, YSZ / Yb2O3 ceramic powder: polyacrylate: deionized water: anhydrous ethanol = 100:102:23:23, to obtain a YSZ / Yb2O3 ceramic-based multiphase mixed liquid;

[0080] Step 3: Granulate and dry the YSZ / Yb2O3 ceramic-based multiphase mixed liquid prepared in step 2; the inlet temperature of the spray granulator is 340°C, the outlet temperature is 115°C, the nozzle speed is 34r / min, and the peristaltic pump speed is 15r / min, to obtain the granulated YSZ / Yb2O3 sprayable ceramic powder;

[0081] Step 4: Use 80 and 240 grit sandpaper to grind and clean the nickel-based high-temperature alloy substrate in turn, and then sandblast aluminum oxide to obtain a nickel-based high-temperature alloy substrate with a certain roughness;

[0082] Using supersonic atmospheric plasma spraying technology to spray NiCrAlY alloy powder on the surface of the roughened nickel-based high-temperature alloy substrate to form a NiCrAlY alloy transition layer; the thickness of the NiCrAlY alloy transition layer is 90 μm, the spraying power is 49 kW, the argon flow rate used in the spraying process is 68 slpm, the hydrogen flow rate is 7 slpm, the spraying current is 845 A, and the voltage is 45 V;

[0083] Step 5: Use supersonic atmospheric plasma spraying technology to spray the YSZ / Yb2O3 sprayable ceramic powder obtained in step 3 on the NiCrAlY alloy transition layer formed in step 4 to form a YSZ / Yb2O3 ceramic layer, and finally obtain an ytterbium-doped high-temperature abradable sealing coating; the spraying power is 49kW, the argon flow rate during spraying is 68slpm, the hydrogen flow rate is 7slpm, the spraying current is 830A, and the voltage is 44V; the thickness of the YSZ / Yb2O3 ceramic layer is 330μm.

[0084] Example 5

[0085] A ytterbium-doped high-temperature abradable sealing coating comprises a nickel-based high-temperature alloy substrate layer, a NiCrAlY alloy transition layer and a YSZ / Yb2O3 ceramic layer which are stacked in sequence; the raw materials of the YSZ / Yb2O3 ceramic layer include 96g YSZ ceramic powder and 4g ytterbium oxide powder.

[0086] A method for preparing an ytterbium-doped high-temperature abradable sealing coating comprises the following steps:

[0087] Step 1: Mix 96g of YSZ ceramic powder and 4g of ytterbium oxide powder and ball mill them at 230r / min for 8h to obtain a uniformly mixed powder mixture; continue to stir at 800r / min and 190°C until the powder mixture becomes a gel; then dry the gel mixture at 103°C for 8h to obtain a uniformly mixed powder to be sintered; sinter the powder to be sintered in stages, wherein the temperature is increased from room temperature to 300°C at 8°C / min, and then increased to 950°C at 6°C / min, and kept at 950°C for 1h, and then increased to 1250°C at 4°C / min, and kept at 1250°C for 8h to obtain YSZ / Yb2O3 ceramic powder;

[0088] Step 2: The YSZ / Yb2O3 ceramic powder prepared in step 1 is mixed with polyacrylate, deionized water and anhydrous ethanol and ball-milled at 70 r / min for 6 h; by mass ratio, YSZ / Yb2O3 ceramic powder: polyacrylate: deionized water: anhydrous ethanol = 98:95:17:17, to obtain a YSZ / Yb2O3 ceramic-based multiphase mixed liquid;

[0089] Step 3: Granulate and dry the YSZ / Yb2O3 ceramic-based multiphase mixed liquid prepared in step 2; the inlet temperature of the spray granulator is 310°C, the outlet temperature is 105°C, the nozzle speed is 33r / min, and the peristaltic pump speed is 13r / min, to obtain the granulated YSZ / Yb2O3 sprayable ceramic powder;

[0090] Step 4: Use 80 and 240 grit sandpaper to grind and clean the nickel-based high-temperature alloy substrate in turn, and then sandblast aluminum oxide to obtain a nickel-based high-temperature alloy substrate with a certain roughness;

[0091] Using supersonic atmospheric plasma spraying technology to spray NiCrAlY alloy powder on the surface of the roughened nickel-based high-temperature alloy substrate to form a NiCrAlY alloy transition layer; the thickness of the NiCrAlY alloy transition layer is 75 μm, the spraying power is 46 kW, the argon flow rate used in the spraying process is 66 slpm, the hydrogen flow rate is 4 slpm, the spraying current is 850 A, and the voltage is 44 V;

[0092] Step 5: Use supersonic atmospheric plasma spraying technology to spray the YSZ / Yb2O3 sprayable ceramic powder obtained in step 3 on the NiCrAlY alloy transition layer formed in step 4 to form a YSZ / Yb2O3 ceramic layer, and finally obtain an ytterbium-doped high-temperature abradable sealing coating; the spraying power is 45kW, the argon flow rate during spraying is 65slpm, the hydrogen flow rate is 4slpm, the spraying current is 820A, and the voltage is 44V; the thickness of the YSZ / Yb2O3 ceramic layer is 340μm.

[0093] Example 6

[0094] A ytterbium-doped high-temperature abradable sealing coating comprises a nickel-based high-temperature alloy substrate layer, a NiCrAlY alloy transition layer and a YSZ / Yb2O3 ceramic layer which are stacked in sequence; the raw materials of the YSZ / Yb2O3 ceramic layer include 98g YSZ ceramic powder and 2g ytterbium oxide powder.

[0095] A method for preparing an ytterbium-doped high-temperature abradable sealing coating comprises the following steps:

[0096] Step 1: Mix 98g of YSZ ceramic powder and 2g of ytterbium oxide powder and ball mill them at 220r / min for 8h to obtain a uniformly mixed powder mixture; continue to stir at 750r / min and 185°C until the powder mixture becomes a gel; then dry the gel mixture at 105°C for 8h to obtain a uniformly mixed powder to be sintered; sinter the powder to be sintered in stages, wherein the temperature is increased from room temperature to 300°C at 10°C / min, and then increased to 950°C at 8°C / min, and kept at 950°C for 1h, and then increased to 1250°C at 4°C / min, and kept at 1250°C for 8h to obtain YSZ / Yb2O3 ceramic powder;

[0097] Step 2: The YSZ / Yb2O3 ceramic powder prepared in step 1 is mixed with polyacrylate, deionized water and anhydrous ethanol and ball-milled at 65 r / min for 4 h; by mass ratio, YSZ / Yb2O3 ceramic powder: polyacrylate: deionized water: anhydrous ethanol = 96:98:18:18, to obtain a YSZ / Yb2O3 ceramic-based multiphase mixed liquid;

[0098] Step 3: Granulate and dry the YSZ / Yb2O3 ceramic-based multiphase mixed liquid prepared in step 2; the inlet temperature of the spray granulator is 320°C, the outlet temperature is 100°C, the nozzle speed is 36r / min, and the peristaltic pump speed is 13r / min, to obtain the granulated YSZ / Yb2O3 sprayable ceramic powder;

[0099] Step 4: Use 80 and 240 grit sandpaper to grind and clean the nickel-based high-temperature alloy substrate in turn, and then sandblast aluminum oxide to obtain a nickel-based high-temperature alloy substrate with a certain roughness;

[0100] Using supersonic atmospheric plasma spraying technology to spray NiCrAlY alloy powder on the surface of the roughened nickel-based high-temperature alloy substrate to form a NiCrAlY alloy transition layer; the thickness of the NiCrAlY alloy transition layer is 80 μm, the spraying power is 45 kW, the argon flow rate used in the spraying process is 70 slpm, the hydrogen flow rate is 4 slpm, the spraying current is 840 A, and the voltage is 44 V;

[0101] Step 5: Use supersonic atmospheric plasma spraying technology to spray the YSZ / Yb2O3 sprayable ceramic powder obtained in step 3 on the NiCrAlY alloy transition layer formed in step 4 to form a YSZ / Yb2O3 ceramic layer, and finally obtain an ytterbium-doped high-temperature abradable sealing coating; the spraying power is 45kW, the argon flow rate is 70slpm, the hydrogen flow rate is 7slpm, the spraying current is 840A, and the voltage is 44V during the spraying process; the thickness of the YSZ / Yb2O3 ceramic layer is 335μm.

[0102] Reference Figure 1 The ytterbium-doped high-temperature abradable sealing coating prepared by the present invention has a three-layer structure, namely, a nickel-based high-temperature alloy base layer-a NiCrAlY alloy transition layer-a YSZ / Yb2O3 ceramic layer.

[0103] Reference Figure 2 The YSZ / Yb2O3 ceramic powder prepared by the high temperature solid phase synthesis method of the present invention has a large number of obvious irregular geometric flake structures, and the irregular geometric flake structures are Yb2O3 crystals.

[0104] Reference Figure 3The YSZ / Yb2O3 sprayable ceramic powder prepared by the present invention has a spherical structure and can be used as a good spray powder; during the spray granulation process, the precursor solution is atomized into small droplets, and these droplets tend to form a shape with the smallest surface area due to the effect of surface tension during the flight in the air, showing a spherical structure; Figure 3 (b) Figure 3 (a) is a partial enlarged view of Figure 3 (b) It can be seen that the YSZ / Yb2O3 sprayable ceramic powder has an obvious irregular strip crystal structure. This irregular strip crystal structure is Yb2O3 crystals, which are scattered and filled between YSZ agglomerates.

[0105] Reference Figure 4 (b), compared with YSZ abradable sealing coating ( Figure 4 (a)), the ytterbium-doped high-temperature abradable sealing coating prepared by the present invention has an obvious porous structure. After adding Yb2O3, the porosity of the high-temperature abradable sealing coating prepared by the present invention is improved, which can improve the thermal stress distribution, enhance the thermal shock resistance, and improve the hardness of the coating, thereby improving the abradability of the coating.

[0106] Reference Figure 5 , Figure 5 (1)-(6) in the figure are hardness dot diagrams. Figure 5 (1)- Figure 5 (3) is the hardness dot diagram of the YSZ abradable sealing coating, and its hardness values ​​are 630.8HV, 607.3HV, and 610.1HV respectively; Figure 5 (4)- Figure 5 (6) is a dot diagram of the hardness of the ytterbium-doped high-temperature abradable sealing coating, and its hardness values ​​are 535.3HV, 497.6HV, and 521.6HV, respectively. Compared with the YSZ abradable sealing coating, the ytterbium-doped high-temperature abradable sealing coating prepared by the present invention has a lower hardness value and improved abradability. This is because the ytterbium-doped high-temperature abradable sealing coating introduces Yb2O3 crystals to increase its porosity, and the Yb2O3 layer also appears as a lubricating phase structure, which improves the hardness value and protects the blades during operation.

[0107] Reference Figure 6 (b), compared with YSZ abradable sealing coating ( Figure 6(a)), the wear volume of the ytterbium-doped high-temperature abradable sealing coating prepared by the present invention increased, and the friction depth increased by 12.92%; the increase in porosity and solid solution caused the hardness, Young's modulus, fracture toughness and other parameters of the material to change. The polycrystalline ceramic has fewer slip systems, and cracks will directly expand under the condition of no plastic deformation under the action of external force, resulting in ceramic spalling failure. Crack closure will occur when the porous material is compressed, and the tensile strength is about one order of magnitude lower than the compressive strength. During the friction and wear process, the coating with lower hardness rubs against the grinding ball, and the coating is subjected to the combined action of positive pressure and tangential force. The ytterbium-doped high-temperature abradable sealing coating with a high friction coefficient is subjected to a larger friction force, thereby increasing the wear volume of the coating; compared with the YSZ abradable sealing coating, the ytterbium-doped high-temperature abradable sealing coating has stronger abradability, and due to the improvement of porosity and hardness value, the concentration of thermal stress is avoided, so that the coating life is longer, which is more conducive to protecting the blades.

[0108] Figure 7 It is a two-dimensional wear scar depth curve of the ytterbium-doped high-temperature abradable sealing coating and the YSZ abradable sealing coating prepared by the present invention, wherein: Figure 7 (a) and Figure 7 (b) The original data of the YSZ abradable sealing coating and the fitted approximate curve area diagram; Figure 7 (c) and Figure 7 (d) The original data of the Yb-doped high-temperature abradable sealing coating and the approximate curve area diagram after fitting, respectively; compared with the YSZ abradable sealing coating (1.37×10 4 μm 2 ), the wear area of ​​the Yb-doped high-temperature abradable sealing coating after fitting is 3.65×10 4 μm 2 , with a larger friction depth and width, indicating that the abradability of the ytterbium-doped high-temperature abradable sealing coating has increased.

[0109] Reference Figure 8 (b), compared with YSZ abradable sealing coating ( Figure 8 (a)), the sample was subjected to thirty shocks by a thermal shock device built in the laboratory ( Fig. 9), the edges of the ytterbium-doped high-temperature abradable sealing coating prepared by the present invention are intact, and the coating cracks and peels off, while the YSZ abradable sealing coating cracks and the coating surface peels off on a large scale. Because Yb2O3 is added to the high-temperature abradable sealing coating of the present invention, when the coating is subjected to high-temperature thermal shock, the thermal expansion coefficient of the ceramic layer is close to that of the transition layer and the substrate, making it not easy to crack and peel off on a large scale, and the porosity is improved compared with the YSZ abradable sealing coating, which prevents the thermal stress from being too concentrated during the high-temperature shock process so that the coating cracks locally, which further improves the thermal shock resistance of the coating, indicating that the thermal shock resistance of the ytterbium-doped high-temperature abradable sealing coating prepared by the present invention is more excellent.

[0110] Fig. 9 This is a thermal shock test diagram of the ytterbium-doped high-temperature abradable sealing coating prepared by the present invention. Aviation kerosene and oxygen are input into the pipeline at the rear end of the flame jet device. An ignition plug is arranged inside the jet device, and the surface temperature of the coating is detected by an infrared emission device. The temperature of the flame jet is controlled by controlling the pressure and flow of the aviation kerosene and the pressure and flow of the oxygen.

Claims

1. An ytterbium-doped high-temperature abradable sealing coating, characterized in that: It includes a nickel-based high-temperature alloy substrate layer, a NiCrAlY alloy transition layer and a YSZ / Yb2O3 ceramic layer which are stacked in sequence. The raw materials of the YSZ / Yb2O3 ceramic layer include YSZ ceramic powder and Yb2O3 lubricating phase. The mass ratio of YSZ ceramic powder: Yb2O3 lubricating phase is (90-98): (2-10).

2. The ytterbium-doped high-temperature abradable sealing coating according to claim 1, characterized in that: The raw material of the NiCrAlY alloy transition layer is NiCrAlY alloy powder.

3. The ytterbium-doped high-temperature abradable sealing coating according to claim 1 or 2, characterized in that: The thickness of the NiCrAlY alloy transition layer is 70-100 μm.

4. The ytterbium-doped high-temperature abradable sealing coating according to claim 1, characterized in that: The thickness of the YSZ / Yb2O3 ceramic layer is not less than 300 μm.

5. A method for preparing an ytterbium-doped high-temperature abradable sealing coating according to any one of claims 1 to 4, characterized in that: The following steps are involved: Step 1: Mix YSZ ceramic powder and Yb2O3 powder, ball mill and stir until the powder mixture becomes gel; dry and sinter the gel powder in sequence to obtain YSZ / Yb2O3 ceramic powder; by mass ratio, YSZ ceramic powder: Yb2O3 powder = (90-98): (2-10); Step 2: ball-milling the YSZ / Yb2O3 ceramic powder, binder, deionized water and anhydrous ethanol obtained in step 1 to obtain a YSZ / Yb2O3 ceramic-based multiphase mixed solution; by mass ratio, YSZ / Yb2O3 ceramic powder: binder: deionized water: anhydrous ethanol = (96-106): (94-104): (15-25): (15-25); the binder is polyacrylate or polymethyl methacrylate; Step 3: Granulate and dry the YSZ / Yb2O3 ceramic multiphase mixed solution obtained in step 2 to obtain granulated YSZ / Yb2O3 sprayable ceramic powder; Step 4: spraying NiCrAlY alloy powder on the surface of the pretreated nickel-based high-temperature alloy substrate to form a NiCrAlY alloy transition layer; Step 5: Spray the YSZ / Yb2O3 sprayable ceramic powder obtained in step 3 onto the NiCrAlY alloy transition layer formed in step 4 to form a YSZ / Yb2O3 ceramic layer, that is, to obtain an ytterbium-doped high-temperature abradable sealing coating.

6. The method for preparing an ytterbium-doped high-temperature abradable sealing coating according to claim 5, characterized in that: The ball milling speed in the step 1 is 200-300r / min, and the ball milling time is 8-10h; the stirring speed is 700-1200r / min, and the stirring temperature is 180-220°C; the drying temperature is 90-105°C, and the drying time is 8-10h; the sintering conditions are to increase the temperature from room temperature to 300°C at a heating rate of 8-10°C / min, continue to increase the temperature from 300 to 950°C at a heating rate of 6-8°C / min, keep warm at 950°C for 1-1.5h, then increase the temperature to 1250°C at a heating rate of 4-6°C / min, and keep warm at 1250°C for 8-10h.

7. The method for preparing an ytterbium-doped high-temperature abradable sealing coating according to claim 5, characterized in that: The ball milling speed in step 2 is 60-90 r / min, and the ball milling time is 4-6 h.

8. The method for preparing an ytterbium-doped high-temperature abradable sealing coating according to claim 5, characterized in that: In step 3, a spray granulator is used for granulation and drying. The inlet temperature of the spray granulator is 300-350° C., the outlet temperature is 100-120° C., the nozzle speed is 32-36 r / min, and the speed of the peristaltic pump is 13-15 r / min.

9. The method for preparing an ytterbium-doped high-temperature abradable sealing coating according to claim 5, characterized in that: The pretreatment process of the nickel-based high-temperature alloy substrate layer in step 4 is: grinding and cleaning the nickel-based high-temperature alloy substrate using 80 and 240 mesh sandpapers in turn, and then sandblasting aluminum oxide to obtain a nickel-based high-temperature alloy substrate with a certain roughness.

10. The method for preparing an ytterbium-doped high-temperature abradable sealing coating according to claim 5, characterized in that: Both step 4 and step 5 are sprayed by supersonic atmospheric plasma spraying process. The spraying power used in the spraying process of step 4 and step 5 is 45-50kW, the argon flow rate is 65-70slpm, and the hydrogen flow rate is 4-7slpm; the spraying current in step 4 is 830-850A, and the voltage is 44-45V; the spraying current in step 5 is 820-840A, and the voltage is 43-44V.

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