High-temperature abradable sealing coating and preparation method thereof

Abstract

The invention discloses a 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 / CaCO3 ceramic layer which are sequentially arranged in a stacked mode, the YSZ / CaCO3 ceramic layer is prepared from YSZ ceramic powder and calcium carbonate powder, and the mass ratio of the YSZ ceramic powder to the calcium carbonate powder is (92-97): (3-8); ySZ / CaCO3 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 process, the YSZ / CaCO3 ceramic powder is sprayed on the NiCrAlY alloy transition layer to form a YSZ / CaCO3 ceramic layer, and the 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 and good thermal shock resistance.

Description

Technical Field

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

[0002] Yttria-stabilized zirconia (YSZ), commonly used as abradable sealing coatings, has been widely used in aero-engines to minimize the gap between the coating and the rotating blades, thereby further improving compressor efficiency and reducing fuel consumption. It is worth noting that the abradable sealing coating needs to be soft enough to protect the blades from damage in certain complex environments. As the complex operating conditions of high thrust-to-weight ratio aero-engines become more and more demanding, traditional YSZ coatings can no longer meet the growing performance requirements such as high temperature stability, wear resistance, good thermal shock resistance, and excellent corrosion resistance. Among these physical and chemical properties, the thermal shock resistance of the coating is an important indicator for evaluating the application availability of abradable sealing coatings. It is reported that the service life of abradable sealing coatings during thermal shock cycles is mainly affected by the coating, bonding layer, and matrix alloy structure. Further improving the service life of abradable sealing coatings has always been a key research direction for thermal spraying.

[0003] In recent years, research on improving the performance of YSZ coatings has attracted considerable attention. However, most of the detailed studies on the thermal shock resistance of YSZ have focused on the field of thermal barrier coatings. Dedicated and detailed studies on the thermal shock behavior of YSZ wear-resistant sealing coatings have rarely been reported. It is well known that YSZ coatings cannot be used for a long time at relatively high temperatures (above 1150°C) due to the phase transition behavior from tetragonal phase to monoclinic phase or cubic phase, which may further lead to large destructive volume changes and ultimately cause coating spalling. In addition, the poor sintering resistance of YSZ can reduce strain compliance and cause further severe residual stresses in the coating during thermal shock cycles. It has been reported that the pores in the coating can balance the mismatch in thermal expansion coefficients.

[0004] The service life of existing YSZ ceramic materials will drop sharply when the service temperature exceeds 1150℃. As the thrust ratio of aircraft engines continues to increase, the service temperature of high-temperature abradable sealing coatings is also rising. Under higher service temperature conditions, the YSZ coating will peel off as a whole, which seriously restricts the increase in the temperature of aircraft engines.

[0005] XM Sun, LZ Du, et al. (Sun, XM Du, LZ Lan, H. Zhang, HF Liu, RY Wang, ZG Fang, SG Huang, CB Liu, ZAZ Hang, WG Study on thermal shock behavior of YSZ abradable sealing coating prepared by mixed solution precursor plasma spraying [J]. Surface & Coatings Technology, 2020, 397 (1).) from the Chinese Academy of Sciences used plasma spraying of a mixed solution of YSZ solution precursor and YSZ nanoparticles to obtain a YSZ wear-resistant sealing coating, but the service temperature of the coating was low (service temperature: 1150°C), and the preparation process of the solution precursor was relatively complicated. Summary of the invention

[0006] In order to overcome the shortcomings of the above-mentioned prior art, the purpose of the present invention is to provide a high-temperature abradable sealing coating and a preparation method thereof, wherein YSZ / CaCO3 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 using a supersonic atmospheric plasma spraying process to form a NiCrAlY alloy transition layer, and YSZ / CaCO3 ceramic powder is sprayed on the NiCrAlY alloy transition layer to form a YSZ / CaCO3 ceramic layer, thereby obtaining a high-temperature abradable sealing coating having the characteristics of high service temperature, coating not easy to crack and peel off, high porosity, simple preparation process and good thermal shock resistance.

[0007] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0008] A high-temperature abradable sealing coating comprises a nickel-based high-temperature alloy substrate layer, a NiCrAlY alloy transition layer and a YSZ / CaCO3 ceramic layer which are stacked in sequence. The raw materials of the YSZ / CaCO3 ceramic layer include YSZ ceramic powder and calcium carbonate powder. The mass ratio of YSZ ceramic powder to calcium carbonate powder is (92-97): (3-8).

[0009] The material of the NiCrAlY alloy transition layer is NiCrAlY alloy powder.

[0010] The thickness of the NiCrAlY alloy transition layer is 90-150 μm.

[0011] The thickness of the YSZ / CaCO3 ceramic layer is not less than 350 μm.

[0012] A method for preparing a high-temperature abradable sealing coating comprises the following steps:

[0013] Step 1: Mix YSZ ceramic powder and pore-forming agent, ball-mill and stir until the powder mixture becomes gel-like; dry and sinter the gel-like powder in sequence to obtain YSZ / CaCO3 ceramic powder; by mass ratio, YSZ ceramic powder: pore-forming agent = (92-97): (3-8); the pore-forming agent is calcium carbonate;

[0014] Step 2: ball-milling the YSZ / CaCO3 ceramic powder, binder, deionized water and anhydrous ethanol obtained in step 1 to obtain a YSZ / CaCO3 ceramic-based multiphase mixed solution; by mass ratio, YSZ / CaCO3 ceramic powder: binder: deionized water: anhydrous ethanol = (98-102): (94-104): (15-25): (15-25); the binder is polyvinyl alcohol or polyacrylic acid;

[0015] Step 3: Granulate and dry the YSZ / CaCO3 ceramic multiphase mixed solution obtained in step 2 to obtain YSZ / CaCO3 multiphase granulated powder;

[0016] 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;

[0017] Step 5: Spray the YSZ / CaCO3 multiphase granulated powder obtained in step 3 onto the NiCrAlY alloy transition layer formed in step 4 to form a YSZ / CaCO3 ceramic layer, that is, a high-temperature abradable sealing coating.

[0018] The ball milling speed in the step 1 is 300-400r / min, and the ball milling time is 9-11h; the drying temperature is 80-110°C, and the drying time is 9-11h; the sintering conditions are heating to 500°C at a heating rate of 8-10°C / min, then heating to 900°C at 6-8°C / min, keeping at 900°C for 1-1.5h, then heating to 1300°C at 5-8°C / min, keeping at 1300°C for 1-1.5h, then heating to 1600°C at 4-6°C / min, and keeping at 1600°C for 8-10h.

[0019] The ball milling speed in step 2 is 70-100 r / min, and the ball milling time is 4-6 h.

[0020] In step 3, a spray granulator is used for granulation and drying. The inlet temperature of the spray granulator is 270-360° C., the outlet temperature is 90-130° C., the nozzle speed is 30-35 r / min, and the peristaltic pump speed is 12-16 r / min.

[0021] The pretreatment process of the nickel-based high-temperature alloy substrate layer in step 4 is: the alloy substrate is polished with 80, 240, and 600 grit sandpaper in sequence, and then ultrasonically cleaned, and then the surface is roughened by sandblasting to form a nickel-based high-temperature alloy substrate layer with a roughness RA of 0.4-0.5.

[0022] Both step 4 and step 5 are sprayed by supersonic atmospheric plasma spraying process, the spraying power in step 4 is 35-45kW, and the spraying power in step 5 is 40-55kW; the argon flow rate used in the spraying process of step 4 and step 5 is 75-80slpm, the hydrogen flow rate is 3-6slpm, the spraying current is 830-850A, and the voltage is 44-45V.

[0023] Compared with the prior art, the beneficial effects of the present invention are:

[0024] 1. The porosity of the YSZ / CaCO3 ceramic layer in the high-temperature abradable sealing coating prepared by adding CaCO3 in the present invention is high. The presence of pores reduces the overall hardness of the sealing coating surface, ensures the abradability of the sealing coating, and can be applied to the rotating blades of aircraft engines, with low damage to the rotating blades and excellent friction and wear performance.

[0025] 2. Compared with the existing YSZ ceramic-based abradable sealing coating, the present invention adopts the method of adding CaCO3 powder to YSZ and using atmospheric plasma spraying to increase the porosity between coatings to obtain a high-temperature abradable sealing coating, and the CaCO3 part contained in the granulation ball will be decomposed into CaO and CO2 under the action of high temperature for a very short time during the spraying process. CaO has a high thermal expansion coefficient. Therefore, CaCO3 is doped into YSZ to effectively adjust the thermal expansion coefficient of the overall coating, making it closer to the thermal expansion coefficient of the NiCrAlY alloy transition layer. It is not easy to crack and peel off during thermal shock. It has obvious advantages in a service environment of 1150°C, and no obvious peeling occurs at 1200°C. It has excellent thermal shock resistance.

[0026] 3. The present invention can prepare YSZ / CaCO3 ceramic powder by high-temperature solid-phase reaction with only two raw materials, and its preparation process is simple and can be mass-produced.

[0027] In summary, the present invention forms a NiCrAlY alloy transition layer and a YSZ / CaCO3 ceramic layer in sequence on a nickel-based high-temperature alloy substrate through an atmospheric plasma spraying process, thereby obtaining a high-temperature abradable sealing coating with a high service temperature, a coating that is not prone to cracking and peeling, a simple preparation process, and good thermal shock resistance. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1It is a schematic structural diagram of the high-temperature abradable sealing coating prepared by the present invention.

[0029] Figure 2 The XRD spectrum of the YSZ / CaCO3 ceramic powder prepared by the present invention.

[0030] Figure 3 This is the SEM morphology of YSZ / CaCO3 multiphase granulated powder, where: Figure 3 (a) is at low magnification. Figure 3 (b) is at high magnification.

[0031] Figure 4 It is a SEM picture of the high temperature abradable sealing coating prepared by the present invention.

[0032] Figure 5 It is an optical micrograph of the high temperature abradable sealing coating prepared by the present invention.

[0033] Figure 6 : is a SEM comparison diagram of the high temperature abradable sealing coating prepared by the present invention and the YSZ coating, wherein: Figure 6 (a) is YSZ coating, Figure 6 (b) High temperature abradable sealing coating.

[0034] Figure 7 : is a thermal shock comparison diagram of the high-temperature abradable sealing coating and the YSZ coating prepared by the present invention, wherein: Figure 7 (a) is YSZ coating, Figure 7 (b) High temperature abradable sealing coating.

[0035] Figure 8 It is a thermal shock test parameter diagram of the high-temperature abradable sealing coating prepared by the present invention. DETAILED DESCRIPTION

[0036] The present invention will be described in detail below in conjunction with the accompanying drawings.

[0037] like Figure 1 As shown, a high-temperature abradable sealing coating comprises a nickel-based high-temperature alloy base layer, a NiCrAlY alloy transition layer and a YSZ / CaCO3 ceramic layer which are stacked in sequence, wherein the raw materials of the YSZ / CaCO3 ceramic layer comprise YSZ ceramic powder and calcium carbonate powder, and the mass ratio of YSZ ceramic powder: calcium carbonate powder is (92-97): (3-8); the material of the NiCrAlY alloy transition layer is NiCrAlY alloy powder; the thickness of the NiCrAlY alloy transition layer is 90-150 μm, and the thickness of the YSZ / CaCO3 ceramic layer is not less than 350 μm.

[0038] A method for preparing a high-temperature abradable sealing coating comprises the following steps:

[0039] Step 1: Add ball milling media to the mixed powder of YSZ ceramic powder and pore-forming agent, the ball milling speed is 300-400r / min, the ball milling time is 9-11h, and a uniformly mixed powder mixture is obtained; then dry at 80-110°C for 9-11h to obtain a sintered powder; sinter the sintered powder to obtain YSZ / CaCO3 ceramic powder; the sintering conditions are: heating to 500°C at a heating rate of 8-10°C / min, Then, the temperature is raised to 900°C at 6-8°C / min, kept at 900°C for 1-1.5h, then raised to 1300°C at 5-8°C / min, kept at 1300°C for 1-1.5h, then raised to 1600°C at 4-6°C / min, kept at 1600°C for 8-10h; the ball milling medium is anhydrous ethanol; by mass ratio, YSZ ceramic powder: pore former = (92-97): (3-8), and the pore former is calcium carbonate;

[0040] Step 2: ball-mill the YSZ / CaCO3 ceramic powder, binder, deionized water and anhydrous ethanol obtained in step 1 at a rotation speed of 70-100 r / min for 4-6 hours to obtain a YSZ / CaCO3 ceramic-based multiphase mixed liquid; by mass ratio, YSZ / CaCO3 ceramic powder: binder: deionized water: anhydrous ethanol = (98-102): (94-104): (15-25): (15-25); the binder is polyvinyl alcohol or polyacrylic acid;

[0041] Step 3: Granulate and dry the YSZ / CaCO3 ceramic multiphase mixed liquid obtained in step 2, the inlet temperature of the spray granulator is 270-360°C, the outlet temperature is 90-130°C, the nozzle speed is 30-35r / min, and the speed of the peristaltic pump is 12-16r / min, to obtain YSZ / CaCO3 multiphase granulated powder;

[0042] Step 4: grinding and cleaning the nickel-based high-temperature alloy substrate using 80, 240, and 600 grit sandpaper in sequence, and then sandblasting the surface to form a nickel-based high-temperature alloy substrate layer with a roughness RA of 0.4-0.5; the sandblasting material is aluminum oxide;

[0043] A supersonic atmospheric plasma spraying process is adopted 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 90-150 μm, the spraying power is 35-45 kW, the argon flow rate used in the spraying process is 75-80 slpm, and the hydrogen flow rate is 3-6 slpm; the spraying current is 830-850 A, and the voltage is 44-45 V;

[0044] Step 5: Spray the YSZ / CaCO3 multiphase granulated powder obtained in step 3 onto the NiCrAlY alloy transition layer formed in step 4 using a supersonic atmospheric plasma spraying process to form a YSZ / CaCO3 ceramic layer to obtain a high-temperature abradable sealing coating; the spraying power is 40-55kW, the argon flow rate is 75-80slpm, the hydrogen flow rate is 3-6slpm, the spraying current is 830-850A, and the voltage is 44-45V during the spraying process; the thickness of the YSZ / CaCO3 ceramic layer is not less than 350μm.

[0045] Example 1

[0046] A high-temperature abradable sealing coating comprises a nickel-based high-temperature alloy substrate, a NiCrAlY alloy transition layer and a YSZ / CaCO3 ceramic layer which are stacked in sequence; the raw materials of the YSZ / CaCO3 ceramic layer include 92g YSZ ceramic powder and 8g calcium carbonate powder.

[0047] A method for preparing a high-temperature abradable sealing coating comprises the following steps:

[0048] Step 1: ball-mill 92g YSZ ceramic powder, 8g calcium carbonate powder and a certain amount of anhydrous ethanol at 300r / min for 9h to obtain a uniformly mixed powder mixture; then dry at 80°C for 9h to obtain a powder to be sintered; sinter the powder to be sintered to obtain YSZ / CaCO3 ceramic powder; the sintering conditions are: heating to 500°C at 8°C / min, then heating to 900°C at 6°C / min, keeping at 900°C for 1h, then heating to 1300°C at 5°C / min, keeping at 1300°C for 1h, then heating to 1600°C at 4°C / min, and keeping at 1600°C for 8h;

[0049] Step 2: 100 g of YSZ / CaCO3 ceramic powder, 95 g of polyvinyl alcohol, 23.75 g of deionized water and 23.75 g of anhydrous ethanol were ball milled at 70 r / min for 6 h in a roller ball mill to obtain a YSZ / CaCO3 ceramic-based multiphase mixed liquid;

[0050] Step 3: using a spray granulator to granulate and dry the YSZ / CaCO3 ceramic-based multiphase mixed liquid obtained in step 2 to obtain a YSZ / CaCO3 multiphase granulated powder; the inlet temperature of the spray granulator is 270°C, the outlet temperature is 90°C, the nozzle speed is 30r / min, and the peristaltic pump speed is 12r / min;

[0051] Step 4: The nickel-based high-temperature alloy substrate is polished using 80, 240, and 600 grit sandpapers in sequence, and then the surface is roughened using aluminum oxide sandblasting to form a nickel-based high-temperature alloy substrate layer with a roughness RA of 0.4;

[0052] A supersonic atmospheric plasma spraying process is adopted 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 35 kW, the argon flow rate used in the spraying process is 75 slpm, the hydrogen flow rate is 3 slpm, the spraying current is 830 A, and the voltage is 44 V;

[0053] Step 5: Use supersonic atmospheric plasma spraying technology to spray the YSZ / CaCO3 multiphase granulated powder obtained in step 3 on the NiCrAlY alloy transition layer formed in step 4 to form a YSZ / CaCO3 ceramic layer to obtain a high-temperature abradable sealing coating; the spraying power is 40kW, the argon flow rate is 75slpm, the hydrogen flow rate is 3slpm, the spraying current is 830A, and the voltage is 44V during the spraying process; the thickness of the YSZ / CaCO3 ceramic layer is 350μm.

[0054] Example 2

[0055] A high-temperature abradable sealing coating comprises a nickel-based high-temperature alloy substrate, a NiCrAlY alloy transition layer and a YSZ / CaCO3 ceramic layer which are stacked in sequence; the raw materials of the YSZ / CaCO3 ceramic layer include 93g YSZ ceramic powder and 7g calcium carbonate powder.

[0056] A method for preparing a high-temperature abradable sealing coating comprises the following steps:

[0057] Step 1: ball-mill 93g YSZ ceramic powder, 7g calcium carbonate powder and a certain amount of anhydrous ethanol at 400r / min for 11h to obtain a uniformly mixed powder mixture; then dry at 110°C for 11h to obtain a powder to be sintered; sinter the powder to be sintered to obtain YSZ / CaCO3 ceramic powder; the sintering conditions are: heating to 500°C at 10°C / min, then heating to 900°C at 8°C / min, keeping at 900°C for 1.5h, then heating to 1300°C at 8°C / min, keeping at 1300°C for 1.5h, then heating to 1600°C at 6°C / min, and keeping at 1600°C for 10h;

[0058] Step 2: 98 g of YSZ / CaCO3 ceramic powder, 94 g of polyvinyl alcohol, 25 g of deionized water and 15 g of anhydrous ethanol were ball milled at 80 r / min for 6 h in a roller ball mill to obtain a YSZ / CaCO3 ceramic-based multiphase mixed liquid;

[0059] Step 3: using a spray granulator to granulate and dry the YSZ / CaCO3 ceramic-based multiphase mixed liquid obtained in step 2 to obtain a YSZ / CaCO3 multiphase granulated powder; the inlet temperature of the spray granulator is 360°C, the outlet temperature is 130°C, the nozzle speed is 35r / min, and the peristaltic pump speed is 16r / min;

[0060] Step 4: Grind the nickel-based high-temperature alloy substrate using 80, 240, and 600 grit sandpaper in sequence, and then roughen the surface using aluminum oxide sandblasting to form a nickel-based high-temperature alloy substrate layer with a roughness RA of 0.5;

[0061] A supersonic atmospheric plasma spraying process is adopted 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 150 μm, the spraying power is 38 kW, the argon flow rate used in the spraying process is 80 slpm, the hydrogen flow rate is 6 slpm, the spraying current is 850 A, and the voltage is 45 V;

[0062] Step 5: Use supersonic atmospheric plasma spraying technology to spray the YSZ / CaCO3 multiphase granulated powder obtained in step 3 on the NiCrAlY alloy transition layer formed in step 4 to form a YSZ / CaCO3 ceramic layer to obtain a high-temperature abradable sealing coating; the spraying power is 55kW, the argon flow rate is 80slpm, the hydrogen flow rate is 6slpm, the spraying current is 850A, and the voltage is 45V during the spraying process; the thickness of the YSZ / CaCO3 ceramic layer is 450μm.

[0063] Example 3

[0064] A high-temperature abradable sealing coating comprises a nickel-based high-temperature alloy substrate, a NiCrAlY alloy transition layer and a YSZ / CaCO3 ceramic layer which are stacked in sequence; the raw materials of the YSZ / CaCO3 ceramic layer include 94g YSZ ceramic powder and 6g calcium carbonate powder.

[0065] A method for preparing a high-temperature abradable sealing coating comprises the following steps:

[0066] Step 1: ball mill 94g YSZ ceramic powder, 6g calcium carbonate powder and a certain amount of anhydrous ethanol at 350r / min for 10h to obtain a uniformly mixed powder mixture; then dry at 100℃ for 10h to obtain a powder to be sintered; sinter the powder to be sintered to obtain YSZ / CaCO3 ceramic powder; the sintering conditions are: heating to 500℃ at 9℃ / min, then heating to 900℃ at 7℃ / min, keeping at 900℃ for 1.5h, then heating to 1300℃ at 5℃ / min, keeping at 1300℃ for 1h, then heating to 1600℃ at 5℃ / min, and keeping at 1600℃ for 9h;

[0067] Step 2: 102 g of YSZ / CaCO3 ceramic powder, 104 g of polyvinyl alcohol, 15 g of deionized water and 15 g of anhydrous ethanol were ball milled at 85 r / min for 5 h in a roller ball mill to obtain a YSZ / CaCO3 ceramic-based multiphase mixed liquid;

[0068] Step 3: using a spray granulator to granulate and dry the YSZ / CaCO3 ceramic-based multiphase mixed liquid obtained in step 2 to obtain a YSZ / CaCO3 multiphase granulated powder; the inlet temperature of the spray granulator is 320°C, the outlet temperature is 100°C, the nozzle speed is 33r / min, and the peristaltic pump speed is 15r / min;

[0069] Step 4: The nickel-based high-temperature alloy substrate is polished using 80, 240, and 600 grit sandpapers in sequence, and then the surface is roughened using aluminum oxide sandblasting to form a nickel-based high-temperature alloy substrate layer with a roughness RA of 0.4;

[0070] A supersonic atmospheric plasma spraying process is adopted 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 120 μm, the spraying power is 40 kW, the argon flow rate used in the spraying process is 77 slpm, the hydrogen flow rate is 4 slpm, the spraying current is 840 A, and the voltage is 44.5 V;

[0071] Step 5: Use supersonic atmospheric plasma spraying technology to spray the YSZ / CaCO3 multiphase granulated powder obtained in step 3 on the NiCrAlY alloy transition layer formed in step 4 to form a YSZ / CaCO3 ceramic layer to obtain a high-temperature abradable sealing coating; the spraying power is 45kW, the argon flow rate is 77slpm, the hydrogen flow rate is 4slpm, the spraying current is 840A, and the voltage is 44.5V during the spraying process; the thickness of the YSZ / CaCO3 ceramic layer is 420μm.

[0072] Example 4

[0073] A high-temperature abradable sealing coating comprises a nickel-based high-temperature alloy substrate, a NiCrAlY alloy transition layer and a YSZ / CaCO3 ceramic layer which are stacked in sequence; the raw materials of the YSZ / CaCO3 ceramic layer include 95g YSZ ceramic powder and 5g calcium carbonate powder.

[0074] A method for preparing a high-temperature abradable sealing coating comprises the following steps:

[0075] Step 1: ball mill 95g YSZ ceramic powder, 5g calcium carbonate powder and a certain amount of anhydrous ethanol at 370r / min for 11h to obtain a uniformly mixed powder mixture; then dry at 110°C for 9h to obtain a powder to be sintered; sinter the powder to be sintered to obtain YSZ / CaCO3 ceramic powder; the sintering conditions are: heating to 500°C at 8°C / min, then heating to 900°C at 7°C / min, keeping at 900°C for 1h, then heating to 1300°C at 5°C / min, keeping at 1300°C for 1.5h, then heating to 1600°C at 5°C / min, and keeping at 1600°C for 9h;

[0076] Step 2: 101 g of YSZ / CaCO3 ceramic powder, 98 g of polyvinyl alcohol, 20 g of deionized water and 20 g of anhydrous ethanol were ball milled at 90 r / min for 4 h in a roller ball mill to obtain a YSZ / CaCO3 ceramic-based multiphase mixed liquid;

[0077] Step 3: using a spray granulator to granulate and dry the YSZ / CaCO3 ceramic-based multiphase mixed liquid obtained in step 2 to obtain a YSZ / CaCO3 multiphase granulated powder; the inlet temperature of the spray granulator is 350°C, the outlet temperature is 100°C, the nozzle speed is 34r / min, and the peristaltic pump speed is 14r / min;

[0078] Step 4: Grind the nickel-based high-temperature alloy substrate using 80, 240, and 600 grit sandpaper in sequence, and then roughen the surface using aluminum oxide sandblasting to form a nickel-based high-temperature alloy substrate layer with a roughness RA of 0.5;

[0079] A supersonic atmospheric plasma spraying process is adopted 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 130 μm, the spraying power is 40 kW, the argon flow rate used in the spraying process is 80 slpm, the hydrogen flow rate is 3 slpm, the spraying current is 835 A, and the voltage is 44.7 V;

[0080] Step 5: Use supersonic atmospheric plasma spraying technology to spray the YSZ / CaCO3 multiphase granulated powder obtained in step 3 on the NiCrAlY alloy transition layer formed in step 4 to form a YSZ / CaCO3 ceramic layer to obtain a high-temperature abradable sealing coating; the spraying power is 40kW, the argon flow rate is 80slpm, the hydrogen flow rate is 3slpm, the spraying current is 835A, and the voltage is 44.7V during the spraying process; the thickness of the YSZ / CaCO3 ceramic layer is 410μm.

[0081] Example 5

[0082] A high-temperature abradable sealing coating comprises a nickel-based high-temperature alloy substrate, a NiCrAlY alloy transition layer and a YSZ / CaCO3 ceramic layer which are stacked in sequence; the raw materials of the YSZ / CaCO3 ceramic layer include 96g YSZ ceramic powder and 4g calcium carbonate powder.

[0083] A method for preparing a high-temperature abradable sealing coating comprises the following steps:

[0084] Step 1: ball mill 96g YSZ ceramic powder, 4g calcium carbonate powder and a certain amount of anhydrous ethanol at 370r / min for 11h to obtain a uniformly mixed powder mixture; then dry at 100℃ for 11h to obtain a powder to be sintered; sinter the powder to be sintered to obtain YSZ / CaCO3 ceramic powder; the sintering conditions are: heating to 500℃ at 8℃ / min, then heating to 900℃ at 7℃ / min, keeping at 900℃ for 1.5h, then heating to 1300℃ at 6℃ / min, keeping at 1300℃ for 1.5h, then heating to 1600℃ at 4℃ / min, and keeping at 1600℃ for 8h;

[0085] Step 2: 99 g of YSZ / CaCO3 ceramic powder, 103 g of polyvinyl alcohol, 18 g of deionized water and 18 g of anhydrous ethanol were ball milled at 90 r / min for 4 h in a roller ball mill to obtain a YSZ / CaCO3 ceramic-based multiphase mixed liquid;

[0086] Step 3: using a spray granulator to granulate and dry the YSZ / CaCO3 ceramic-based multiphase mixed liquid obtained in step 2 to obtain a YSZ / CaCO3 multiphase granulated powder; the inlet temperature of the spray granulator is 310°C, the outlet temperature is 105°C, the nozzle speed is 32r / min, and the peristaltic pump speed is 13r / min;

[0087] Step 4: The nickel-based high-temperature alloy substrate is polished using 80, 240, and 600 grit sandpapers in sequence, and then the surface is roughened using aluminum oxide sandblasting to form a nickel-based high-temperature alloy substrate layer with a roughness RA of 0.4;

[0088] A supersonic atmospheric plasma spraying process is adopted 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 140 μm, the spraying power is 45 kW, the argon flow rate used in the spraying process is 78 slpm, the hydrogen flow rate is 5 slpm, the spraying current is 845 A, and the voltage is 44.3 V;

[0089] Step 5: Use supersonic atmospheric plasma spraying technology to spray the YSZ / CaCO3 multiphase granulated powder obtained in step 3 on the NiCrAlY alloy transition layer formed in step 4 to form a YSZ / CaCO3 ceramic layer to obtain a high-temperature abradable sealing coating; the spraying power is 40kW, the argon flow rate is 78slpm, the hydrogen flow rate is 5slpm, the spraying current is 845A, and the voltage is 44.3V during the spraying process; the thickness of the YSZ / CaCO3 ceramic layer is 400μm.

[0090] Example 6

[0091] A high-temperature abradable sealing coating comprises a nickel-based high-temperature alloy substrate, a NiCrAlY alloy transition layer and a YSZ / CaCO3 ceramic layer which are stacked in sequence; the raw materials of the YSZ / CaCO3 ceramic layer include 97g YSZ ceramic powder and 3g calcium carbonate powder.

[0092] A method for preparing a high-temperature abradable sealing coating comprises the following steps:

[0093] Step 1: ball-mill 97g YSZ ceramic powder, 3g calcium carbonate powder and a certain amount of anhydrous ethanol at 315r / min for 9h to obtain a uniformly mixed powder mixture; then dry at 110°C for 11h to obtain a powder to be sintered; sinter the powder to be sintered to obtain YSZ / CaCO3 ceramic powder; the sintering conditions are: heating to 500°C at 10°C / min, then heating to 900°C at 6°C / min, keeping at 900°C for 1h, then heating to 1300°C at 5°C / min, keeping at 1300°C for 1h, then heating to 1600°C at 5°C / min, and keeping at 1600°C for 10h;

[0094] Step 2: 99 g of YSZ / CaCO3 ceramic powder, 103 g of polyvinyl alcohol, 19 g of deionized water and 23 g of anhydrous ethanol were ball milled at 70 r / min for 4 h in a roller ball mill to obtain a YSZ / CaCO3 ceramic-based multiphase mixed liquid;

[0095] Step 3: using a spray granulator to granulate and dry the YSZ / CaCO3 ceramic-based multiphase mixed liquid obtained in step 2 to obtain a YSZ / CaCO3 multiphase granulated powder; the inlet temperature of the spray granulator is 310°C, the outlet temperature is 100°C, the nozzle speed is 35r / min, and the peristaltic pump speed is 16r / min;

[0096] Step 4: Grind the nickel-based high-temperature alloy substrate using 80, 240, and 600 grit sandpaper in sequence, and then roughen the surface using aluminum oxide sandblasting to form a nickel-based high-temperature alloy substrate layer with a roughness RA of 0.5;

[0097] A supersonic atmospheric plasma spraying process is adopted 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 40 kW, the argon flow rate used in the spraying process is 75 slpm, the hydrogen flow rate is 3 slpm, the spraying current is 830 A, and the voltage is 44.4 V;

[0098] Step 5: Use supersonic atmospheric plasma spraying technology to spray the YSZ / CaCO3 multiphase granulated powder obtained in step 3 on the NiCrAlY alloy transition layer formed in step 4 to form a YSZ / CaCO3 ceramic layer to obtain a high-temperature abradable sealing coating; the spraying power is 45kW, the argon flow rate is 75slpm, the hydrogen flow rate is 3slpm, the spraying current is 830A, and the voltage is 44.4V during the spraying process; the thickness of the YSZ / CaCO3 ceramic layer is 450μm.

[0099] Figure 1 The schematic diagram of the structure of the high temperature abradable sealing coating prepared by the present invention is composed of Figure 1 It can be seen that the high-temperature abradable sealing coating prepared by the present invention is a three-layer structure, namely, a nickel-based high-temperature alloy base layer-a NiCrAlY alloy transition layer-a YSZ / CaCO3 ceramic layer.

[0100] Figure 2 The XRD pattern of the YSZ / CaCO3 ceramic powder prepared in the present invention is shown in FIG. Figure 2 It can be seen that the diffraction peaks of the YSZ / CaCO3 ceramic powder correspond one to one with the standard PDF cards of YSZ and CaCO3, indicating that the YSZ / CaCO3 ceramic powder prepared by the present invention contains YSZ and CaCO3 phases.

[0101] See also Figure 3 (a) The YSZ / CaCO3 multiphase granulated powder prepared by the present invention has a spherical structure and can be used as a good spray powder; Figure 3 (b) Figure 3 (a) Enlarged view of the red box, Figure 3 (b) An obvious wedge-shaped structure can be seen, which is CaCO3 crystal.

[0102] See also Figure 4 The high-temperature abradable sealing coating prepared by the present invention is composed of a large amount of molten granulated powder, is flat, has partially molten particles and good porosity, has the characteristics of high deposition efficiency and can be mass-produced.

[0103] See also Figure 5 The transition layer thickness of the high-temperature abradable sealing coating prepared by the present invention is 90 μm, and the ceramic layer thickness is about 350 μm. It can be seen that it has a controllable thickness and a simple preparation process.

[0104] See also Figure 6 (b), compared with YSZ abradable sealing coating ( Figure 6 (a)), the high-temperature abradable sealing coating prepared by the present invention has an obvious pore structure. After adding CaCO3, the porosity of the high-temperature abradable sealing coating prepared by the present invention is improved, which can improve the thermal stress distribution and enhance the thermal shock resistance.

[0105] See also Figure 7 (b), with YSZ abradable sealing coating ( Figure 7 (a)) compared with the high temperature abradable sealing coating prepared by the present invention at 1200℃( Figure 8 ) The edges of the YSZ abradable sealing coating were intact under thermal shock, and no cracking or peeling of the coating occurred, while cracks occurred at the edges of the YSZ abradable sealing coating, and part of the coating fell off, indicating that the high-temperature abradable sealing coating prepared by the present invention has the characteristics of good thermal shock resistance and the coating is not easy to crack or peel off.

Claims

1. A high temperature abradable sealing coating, characterized in that: It includes a nickel-based high-temperature alloy base layer, a NiCrAlY alloy transition layer and a YSZ / CaCO3 ceramic layer which are stacked in sequence. The raw materials of the YSZ / CaCO3 ceramic layer include YSZ ceramic powder and calcium carbonate powder. The mass ratio of YSZ ceramic powder: calcium carbonate powder is (92-97): (3-8).

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

3. A high temperature abradable sealing coating according to claim 1 or 2, characterized in that: The thickness of the NiCrAlY alloy transition layer is 90-150 μm.

4. A high temperature abradable sealing coating according to claim 1, characterized in that: The thickness of the YSZ / CaCO3 ceramic layer is not less than 350 μm.

5. A method for preparing a 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 pore-forming agent, ball-mill and stir until the powder mixture becomes gel-like; dry and sinter the gel-like powder in sequence to obtain YSZ / CaCO3 ceramic powder; by mass ratio, YSZ ceramic powder: pore-forming agent = (92-97): (3-8); the pore-forming agent is calcium carbonate; Step 2: ball-milling the YSZ / CaCO3 ceramic powder, binder, deionized water and anhydrous ethanol obtained in step 1 to obtain a YSZ / CaCO3 ceramic-based multiphase mixed solution; by mass ratio, YSZ / CaCO3 ceramic powder: binder: deionized water: anhydrous ethanol = (98-102): (94-104): (15-25): (15-25); the binder is polyvinyl alcohol or polyacrylic acid; Step 3: Granulate and dry the YSZ / CaCO3 ceramic multiphase mixed solution obtained in step 2 to obtain YSZ / CaCO3 multiphase granulated 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 / CaCO3 multiphase granulated powder obtained in step 3 onto the NiCrAlY alloy transition layer formed in step 4 to form a YSZ / CaCO3 ceramic layer, that is, a high-temperature abradable sealing coating.

6. The method for preparing a high temperature abradable sealing coating according to claim 5, characterized in that: The ball milling speed in the step 1 is 300-400r / min, and the ball milling time is 9-11h; the drying temperature is 80-110°C, and the drying time is 9-11h; the sintering conditions are heating to 500°C at a heating rate of 8-10°C / min, then heating to 900°C at 6-8°C / min, keeping at 900°C for 1-1.5h, then heating to 1300°C at 5-8°C / min, keeping at 1300°C for 1-1.5h, then heating to 1600°C at 4-6°C / min, and keeping at 1600°C for 8-10h.

7. The method for preparing a high-temperature abradable sealing coating according to claim 5, characterized in that: The ball milling speed in step 2 is 70-100 r / min, and the ball milling time is 4-6 h.

8. The method for preparing a 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 270-360° C., the outlet temperature is 90-130° C., the nozzle speed is 30-35 r / min, and the peristaltic pump speed is 12-16 r / min.

9. The method for preparing a 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: the alloy substrate is polished with 80, 240, and 600 grit sandpaper in sequence, and then ultrasonically cleaned, and then the surface is roughened by sandblasting to form a nickel-based high-temperature alloy substrate layer with a roughness RA of 0.4-0.

5.

10. The method for preparing a 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 in step 4 is 35-45kW, and the spraying power in step 5 is 40-55kW; the argon flow rate used in the spraying process of step 4 and step 5 is 75-80slpm, and the hydrogen flow rate is 3-6slpm; the spraying current is 830-850A, and the voltage is 44-45V.

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