Thermal barrier coatings and their composite processes for turbine guide vanes

Abstract

This invention relates to a thermal barrier coating for turbine guide vanes and its composite process, belonging to the field of protective coating technology. The invention first protects the blade body using tooling, then thermally sprays an MCrAlY / YSZ thermal barrier coating onto the rim plate. Next, using tooling to protect the rim plate area, a physical vapor deposition (PVD) process is used to prepare the MCrAlY / YSZ thermal barrier coating on the blade body. The thermal spraying method produces a thick thermal barrier coating with good insulation, effectively protecting the rim plate and preventing cracking. The PVD process effectively reduces coating peeling, prevents pore blockage, and avoids the adhesion of CMAS (Complex Motion Assay) deposits on the surface. This composite process for preparing thermal barrier coatings for high-pressure turbine guide vanes can significantly improve the service life of the blades.

Description

Technical Field

[0001] This invention belongs to the field of protective coating technology, and in particular relates to a thermal barrier coating for turbine guide vanes and its composite process. Background Technology

[0002] Turbine guide vanes operate in harsh environments, enduring long-term impact and erosion from high-temperature combustion gases. To improve their service life and reliability, a film cooling structure is employed internally, while a thermal barrier coating is applied to the outer surface. The thermal barrier coating on the outer surface of the turbine guide vane consists of a MCrAlY metal bond substrate with good oxidation resistance and a YSZ ceramic surface layer with low thermal conductivity. The MCrAlY metal bond substrate is primarily composed of the β-NiAl phase, while the YSZ ceramic surface layer is mainly ZrO2·Y2O3. Currently, the mainstream processes for preparing thermal barrier coatings are thermal spraying and physical vapor deposition (PVD). Each method has its advantages and disadvantages. Thermal spraying offers advantages such as simple process, high production efficiency, low cost, and good thermal insulation, but the resulting coating has a layered structure and poor resistance to thermal cycling. Physical vapor deposition (PVD) produces a columnar crystalline structure with good resistance to thermal cycling, but its disadvantages include low production efficiency, high cost, and poor thermal insulation.

[0003] In the preparation of thermal barrier coatings for high-pressure turbine guide vanes, both processes have entered mass production. However, during the use of the blade coatings, due to the characteristics of the coating preparation processes, the following problems exist:

[0004] The base layer of the thermal barrier coating for high-pressure turbine guide vanes prepared by thermal spraying is generally a supersonic flame-sprayed MCrAlY bonding layer, and the top layer is a plasma-sprayed YSZ ceramic surface layer. Due to its process characteristics, the coating can uniformly cover the blade body and edge plates. The coating is relatively thick and has a layered structure, which provides good thermal insulation. However, the surface roughness of the coating is relatively high. During use, CMAS (CaO-MgO-Al2O3-SiO2) environmental deposits are easily attached, which can block the air film pores. The layered structure has high internal stress and poor resistance to thermal cycling. After a certain period of use, the blade coating often peels off over a large area.

[0005] The base layer for thermal barrier coatings on high-pressure turbine guide vanes prepared by physical vapor deposition is typically a multi-arc ion-plated MCrAlY bonding layer, followed by a YSZ ceramic surface layer prepared by electron beam physical vapor deposition (EB-PVD). The MCrAlY bonding layer prepared by multi-arc ion plating exhibits superior oxidation and thermal corrosion resistance compared to bonding layers prepared by thermal spraying. However, this process suffers from a linear effect. Due to the structural characteristics of high-pressure turbine guide vanes, the rim coating is very thin during preparation, only about 1 / 10 to 1 / 8 the thickness of the blade body coating. The blade body coating has a moderate thickness and low surface roughness. Because of its columnar crystalline structure, the coating exhibits good strain tolerance and resistance to thermal cycling. However, after a certain period of use, the thin coating at the rim provides insufficient protection, frequently leading to cracking at the rim. Summary of the Invention

[0006] The purpose of this invention is to provide a thermal barrier coating for turbine guide vanes and its composite process. The technique employed involves first protecting the blade body with tooling, then thermally spraying an MCrAlY / YSZ thermal barrier coating onto the shroud. Next, using tooling to protect the shroud area, a physical vapor deposition (PVD) process is used to prepare the MCrAlY / YSZ thermal barrier coating on the blade body. The thermal spraying method produces a thick thermal barrier coating with excellent insulation, effectively protecting the shroud and preventing cracking. The PVD process effectively reduces coating shedding, prevents pore blockage, and avoids the adhesion of CMAS (Complex Environment Assay) deposits on the surface. This composite process for preparing thermal barrier coatings for high-pressure turbine guide vanes can significantly improve the service life of the blades.

[0007] The key point of this invention lies in the preparation of a thermal barrier coating and method for turbine guide vanes using a composite process; the composite process consists of thermal spraying and physical vapor deposition. First, the blade body is protected using tooling. After dry sandblasting pretreatment of the blade edge, an MCrAlY underlayer is coated using supersonic flame spraying, followed by plasma spraying to prepare a YSZ ceramic surface layer. Then, the blade edge is protected again, and after wet sandblasting pretreatment of the blade body, an MCrAlY underlayer is coated using multi-arc ion plating, followed by electron beam physical vapor deposition of the YSZ ceramic surface layer.

[0008] In summary, the protective coating of the turbine guide vane edge plate consists of a supersonic flame-sprayed MCrAlY underlayer and a plasma-sprayed YSZ top layer, while the protective coating of the blade body consists of a multi-arc ion-plated MCrAlY underlayer and an electron beam physical vapor deposition YSZ top layer.

[0009] To achieve the above objectives, the present invention adopts the following technical solution:

[0010] A thermal barrier coating for turbine guide vanes comprises an MCrAlY underlayer and a YSZ ceramic toplayer. The MCrAlY underlayer consists of 18%–23% Cr, 9%–13.5% Al, 0.6%–1.2% Y, and the remainder Ni by mass percentage. The YSZ ceramic toplayer consists of Zr2O3 doped with 6%–9% Y2O3 by mass percentage.

[0011] The thermal barrier coating on the edge plate of the turbine guide vane is applied by supersonic flame spraying of the MCrAlY underlayer and plasma spraying of the YSZ ceramic surface layer; wherein, the thickness of the MCrAlY underlayer in the edge plate thermal barrier coating is 100μm to 150μm, and the thickness of the YSZ ceramic surface layer is 200μm to 300μm.

[0012] The thermal barrier coating on the blade of the turbine guide vane is formed by multi-arc ion plating of MCrAlY as the base layer and electron beam physical vapor deposition of YSZ ceramic as the surface layer; wherein the thickness of the MCrAlY base layer in the blade thermal barrier coating is 40μm to 70μm and the thickness of the YSZ ceramic surface layer is 100μm to 200μm.

[0013] The thermal barrier coating at the edge plate has a layered structure with a porosity of 6% to 10%; the thermal conductivity of the coating at 1100℃ is 1.212 W / (m·K) to 1.294 W / (m·K).

[0014] The thermal barrier coating on the blade has a columnar crystalline structure, and its resistance to thermal cycling at 1100℃ is more than 50% higher than that of a layered structure of the same thickness.

[0015] The composite process for the thermal barrier coating used on turbine guide vanes is characterized by comprising the following steps:

[0016] Step 1. Protect the blade body of the turbine guide vanes with tooling;

[0017] Step 2. Dry sandblasting treatment is performed on the rim surface of the turbine guide vanes;

[0018] Step 3. Prepare the MCrAlY underlayer of the edging plate using a supersonic flame spraying process;

[0019] Step 4. Prepare the YSZ ceramic surface layer of the edging plate using plasma spraying process;

[0020] Step 5. Use tooling to protect the rim plates of the turbine guide vanes;

[0021] Step 6. Perform wet sandblasting on the turbine guide vane blades to activate the surface of the parts;

[0022] Step 7. Prepare the MCrAlY underlayer for the blade using a multi-arc ion plating process;

[0023] Step 8. Electron beam physical vapor deposition is used to deposit a YSZ ceramic surface layer on the blade.

[0024] The tooling protection in steps 1 and 5 both adopt automated spraying tooling.

[0025] In step 2, during the dry sandblasting process, the abrasive used for sandblasting is white corundum abrasive with a particle size of 36-80 mesh, an air pressure of 0.20MPa-0.40MPa, a sandblasting distance of 80mm-150mm, and a sandblasting angle of 60°-75°.

[0026] In step 3, the process parameters for supersonic flame spraying are: oxygen pressure 150±10PSI, oxygen flow rate 1200±50SCFH, fuel pressure 120±10PSI, fuel flow rate 7.0±2SCFH, powder feeding rate 120g / min~130g / min, spraying distance 350mm~370mm, and spraying angle 75°~90°.

[0027] In step 4, the process parameters for plasma spraying are as follows: the main gas is Ar, with a flow rate of 40±5 NLPM; the secondary gas is H2, with a flow rate of 15±2 NLPM; the current is 550±10A; the powder feeding rate is 80±10g / min; the spraying distance is 90mm~110mm; and the spraying angle is 75°~90°.

[0028] In step 6, the process parameters for wet sand blowing are as follows: the abrasive is white corundum sand with a particle size of 180 mesh to 230 mesh; the white corundum sand content is 20±10%; the air pressure is 0.15±0.2MPa; and the sand blowing distance is 180mm to 250mm.

[0029] After the wet sandblasting is completed, the leaf blades need to be ultrasonically cleaned with deionized water, immersed in acetone solution, and dried in sequence.

[0030] In step 7, the multi-arc ion plating process mainly includes an ion cleaning process and a deposition process; wherein the parameters of the ion cleaning process are: bias voltage U = 500V~700V, arc current I = 70A±2A, duty cycle D = 25%~45%; and the parameters of the deposition process are: bias voltage U = 200V~275V, arc current I = 70A±2A, duty cycle D = 10%~30%.

[0031] In step 8, electron beam physical vapor deposition includes an ion cleaning process and a deposition process; wherein the ion cleaning process parameters are: argon pressure P = 0.04 MPa ~ 0.06 MPa, argon flow rate L = 36 ml / min ~ 38 ml / min, and cleaning time t = 10 ± 2 min; the deposition process parameters are: main vacuum chamber pressure not greater than 1.0 × 10⁻⁶. -3The torr electron gun voltage is 17kV~20kV, the target heating current is 1.2A~1.5A, the workpiece rotation speed is 15r / min, the substrate temperature is 900℃~950℃, and the oxygen flow rate is 200±10ml / min.

[0032] Compared with the prior art, the beneficial effects of the present invention are:

[0033] 1. This invention employs a method of supersonic flame spraying of an MCrAlY underlayer followed by plasma spraying of a YSZ ceramic top layer to prepare a thermal barrier coating for the blade rim, reducing the possibility of rim cracking during service. The rim thermal barrier coating prepared using the method provided by this invention has a layered structure with a porosity of 6%–10%; it exhibits good thermal insulation performance, with a thermal conductivity of 1.212–1.294 W / (m·K) at 1100℃.

[0034] 2. This invention employs a multi-arc ion plating method to coat the blade body with an MCrAlY underlayer, followed by electron beam physical vapor deposition of a YSZ ceramic surface layer to prepare a thermal barrier coating. This solves the problem of easy coating detachment during service. The thermal barrier coating prepared using the method provided by this invention has a columnar crystalline structure, good strain tolerance, and its resistance to thermal cycling at 1100℃ is improved by more than 50% compared to a layered structure of the same thickness.

[0035] 3. By using the composite process provided by this invention, different coating preparation processes are designed and used according to the structural characteristics of the blade and the fin. The prepared guide blade thermal barrier coating has the characteristics of both heat insulation effect and long service life. It can effectively solve the problem that the blade fin can not be solved at the same time as the blade coating peeling off, and significantly improve the service life of the blade coating.

[0036] 4. The coating fixture used in this invention protects the blade body when spraying the rim plate and leaves an appropriate space at the junction of the blade and the rim plate, so that the rim plate can be completely sprayed. At the same time, the coating can be continuously transferred when depositing the coating on the blade body. Attached Figure Description

[0037] Figure 1 This is a schematic diagram of the blade body and shroud of a high-pressure turbine guide vane.

[0038] Figure 2 Cracks in the trailing edge plate of a physical vapor deposition thermal barrier coating for turbine guide vanes during service.

[0039] Figure 3 The thermal barrier coating applied to the turbine guide vanes by thermal spraying peeled off after service.

[0040] Figure 4 Microstructure of the guide vane edge plate with MCrAlY underlayer and YSZ top layer by supersonic flame spraying.

[0041] Figure 5 Microstructure of the guide vane blade with multi-arc ion plating of MCrAlY substrate and electron beam physical vapor deposition of YSZ surface layer.

[0042] Figure 6 Typical metallographic structures for thermal barrier coatings prepared by thermal spraying.

[0043] Figure 7 Typical metallographic structure of thermal barrier coatings prepared by physical vapor deposition. Detailed Implementation

[0044] The present invention will be further described below with reference to the accompanying drawings and specific examples.

[0045] High-pressure turbine guide vanes are generally divided into the blade body and the shroud, and their structure is as follows: Figure 1 As shown. When a thermal barrier coating is prepared using a multi-arc ion-plated MCrAlY underlayer and an electron beam physical vapor deposition YSZ top layer for the turbine guide vanes, cracks appear on the trailing edge plate after a certain period of service, such as... Figure 2 As shown in the figure, the rim coating is relatively thin, and after a certain period of service, localized peeling occurs, leading to obvious cracks in the blade rim. When a turbine guide vane uses supersonic flame spraying of MCrAlY as the underlayer and plasma spraying of YSZ as the top layer to prepare a thermal barrier coating, the coating peeling off the blade after a certain period of service is as follows... Figure 3 As shown in the figure, the coating is relatively rough, covered with yellowish-brown environmental deposits, and surface peeling occurs near the exhaust edge of the blade. To address the problem of coating peeling after service on turbine guide vanes prepared by thermal spraying, and the issue of blade edge cracking after service on thermal barrier coatings prepared by physical vapor deposition, a combined process of thermal spraying and physical vapor deposition is used to prepare the thermal barrier coating for turbine guide vanes. For the turbine guide vane, the blade body is protected by tooling, and the blade edge surface is subjected to dry sandblasting. A supersonic flame spraying process is used to prepare the MCrAlY underlayer, and a plasma spraying process is used to prepare the YSZ top layer. For the turbine guide vane, the blade edge is protected by tooling, and the turbine guide vane body is subjected to wet sandblasting. A multi-arc ion plating process is used to prepare the MCrAlY underlayer, and an electron beam physical vapor deposition process is used to prepare the YSZ ceramic top layer.

[0046] The specific process is as follows:

[0047] Example 1

[0048] The turbine guide vane was protected by a spraying fixture, and the blade edge plate surface was treated with dry sandblasting. The dry sandblasting process parameters were as follows: abrasive type: white corundum abrasive, abrasive particle size: 40 mesh, air pressure: 0.20MPa, sandblasting distance: 80mm, sandblasting angle: 60°~75°.

[0049] A 125±25μm MCrAlY undercoat was applied to the blade edge plate using supersonic flame spraying. The spraying parameters were: oxygen pressure 150±10PSI, oxygen flow rate 1200±50SCFH, fuel pressure 120±10PSI, fuel flow rate 7.0±2SCFH, powder feed rate 110g / min, spraying distance 360mm, and spraying angle 75°~90°.

[0050] A 250±50μm YSZ surface layer was applied to the blade edge plate using plasma spraying. The spraying process parameters were: main gas Ar flow rate 40±5NLPM, secondary gas H2 flow rate 15±2NLPM, current 550±10A, powder feeding rate 80±10g / min, spraying distance 100mm, and spraying angle 75°~90°.

[0051] Physical vapor deposition (PVD) was used to protect the rim plates of the turbine guide vanes. The blade body underwent wet sandblasting, followed by ultrasonic cleaning, acetone immersion, and drying. The wet sandblasting process parameters were: white corundum alumina particle size of 200 mesh, corundum alumina content of 20±10%, air pressure of 0.15±0.2 MPa, and sandblasting distance of 200 mm.

[0052] A 50±5μm MCrAlY underlayer was coated using vacuum arc plating. The ion cleaning process parameters were: bias voltage U = 500V, arc current I = 70A±2A, duty cycle D = 40%. The deposition process parameters were: bias voltage U = 250V, arc current I = 70A±2A, duty cycle D = 20%.

[0053] A 200 μm YSZ ceramic surface layer was prepared using electron beam physical vapor deposition. The ion cleaning process parameters were: argon pressure P = 0.05 MPa, argon flow rate L = 37 ml / min, and cleaning time t = 10 min ± 2. The deposition process parameters were: main vacuum chamber pressure not exceeding 1.0 × 10⁻⁶ m² / min. -3 The torr electron gun voltage is 17kV~20kV, the target heating current is 1.2A~1.5A, the workpiece rotation speed is 15r / min, the substrate temperature is 900℃, and the oxygen flow rate is 200±10ml / min.

[0054] A thermal barrier coating is finally applied to the turbine guide vane. The metallographic structures of the thermal barrier coatings on the blade edge and blade body prepared by this method are shown below. Figure 4 and Figure 5 As shown in the figure, the thermal barrier coating on the blade edge is uniform and dense, while the thermal barrier coating on the blade body exhibits a typical columnar crystalline structure.

[0055] Example 2

[0056] The turbine guide vane was protected by a spraying fixture, and the blade edge plate surface was treated with dry sandblasting. The dry sandblasting process parameters were as follows: abrasive type: white corundum abrasive, abrasive particle size: 40 mesh, air pressure: 0.20MPa, sandblasting distance: 100mm, sandblasting angle: 60°~75°.

[0057] A 125±25μm MCrAlY undercoat was applied to the blade edge plate using supersonic flame spraying. The spraying parameters were: oxygen pressure 150±10PSI, oxygen flow rate 1200±50SCFH, fuel pressure 120±10PSI, fuel flow rate 7.0±2SCFH, powder feed rate 110g / min, spraying distance 360mm, and spraying angle 75°~90°.

[0058] A 250±50μm YSZ surface layer was applied to the blade edge plate using plasma spraying. The spraying process parameters were: main gas Ar flow rate 40±5NLPM, secondary gas H2 flow rate 15±2NLPM, current 550±10A, powder feeding rate 80±10g / min, spraying distance 100mm, and spraying angle 75°~90°.

[0059] Physical vapor deposition (PVD) was used to protect the rim plates of the turbine guide vanes. The blade body underwent wet sandblasting, followed by ultrasonic cleaning, acetone immersion, and drying. The wet sandblasting process parameters were: white corundum alumina particle size of 200 mesh, corundum alumina content of 20±10%, air pressure of 0.15±0.2 MPa, and sandblasting distance of 200 mm.

[0060] A 50±5μm MCrAlY underlayer was coated using vacuum arc plating. The ion cleaning process parameters were: bias voltage U = 600V, arc current I = 70A±2A, duty cycle D = 40%. The deposition process parameters were: bias voltage U = 250V, arc current I = 70A±2A, duty cycle D = 20%.

[0061] A 100 μm YSZ ceramic surface layer was prepared using electron beam physical vapor deposition. The ion cleaning process parameters were: argon pressure P = 0.05 MPa, argon flow rate L = 37 ml / min, and cleaning time t = 10 min ± 2. The deposition process parameters were: main vacuum chamber pressure not exceeding 1.0 × 10⁻⁶ m² / min. -3 The torr electron gun voltage is 17kV~20kV, the target heating current is 1.2A~1.5A, the workpiece rotation speed is 15r / min, the substrate temperature is 950℃, and the oxygen flow rate is 200±10ml / min.

[0062] The final thermal barrier coating structure of the turbine guide vane edge plate is a layered structure, while the thermal barrier coating structure of the blade body is a columnar crystalline structure.

[0063] Example 3

[0064] The turbine guide vane was protected by a spraying fixture, and the blade edge plate surface was treated with dry sandblasting. The dry sandblasting process parameters were as follows: abrasive type: white corundum abrasive, abrasive particle size: 40 mesh, air pressure: 0.20MPa, sandblasting distance: 150mm, sandblasting angle: 60°~75°.

[0065] A 125±25μm MCrAlY undercoat was applied to the blade edge plate using supersonic flame spraying. The spraying parameters were: oxygen pressure 150±10PSI, oxygen flow rate 1200±50SCFH, fuel pressure 120±10PSI, fuel flow rate 7.0±2SCFH, powder feed rate 110g / min, spraying distance 360mm, and spraying angle 75°~90°.

[0066] A 250±50μm YSZ surface layer was applied to the blade edge plate using plasma spraying. The spraying process parameters were: main gas Ar flow rate 40±5NLPM, secondary gas H2 flow rate 15±2NLPM, current 550±10A, powder feeding rate 80±10g / min, spraying distance 100mm, and spraying angle 75°~90°.

[0067] Physical vapor deposition (PVD) was used to protect the rim plates of the turbine guide vanes. The blade body underwent wet sandblasting, followed by ultrasonic cleaning, acetone immersion, and drying. The wet sandblasting process parameters were: white corundum alumina particle size of 230 mesh, corundum alumina content of 20±10%, air pressure of 0.15±0.2 MPa, and sandblasting distance of 200 mm.

[0068] A 50±5μm MCrAlY underlayer was coated using vacuum arc plating. The ion cleaning process parameters were: bias voltage U = 700V, arc current I = 70A±2A, duty cycle D = 40%. The deposition process parameters were: bias voltage U = 250V, arc current I = 70A±2A, duty cycle D = 20%.

[0069] A 150 μm YSZ ceramic surface layer was prepared using electron beam physical vapor deposition. The ion cleaning process parameters were: argon pressure P = 0.05 MPa, argon flow rate L = 37 ml / min, and cleaning time t = 10 min ± 2. The deposition process parameters were: main vacuum chamber pressure not exceeding 1.0 × 10⁻⁶ m² / min. -3 The torr electron gun voltage is 17kV~20kV, the target heating current is 1.2A~1.5A, the workpiece rotation speed is 15r / min, the substrate temperature is 900℃, and the oxygen flow rate is 200±10ml / min.

[0070] The final thermal barrier coating structure of the turbine guide vane edge plate is a layered structure, while the thermal barrier coating structure of the blade body is a columnar crystalline structure.

[0071] Example 4

[0072] The turbine guide vane was protected by a spraying fixture, and the blade edge plate surface was treated with dry sandblasting. The dry sandblasting process parameters were as follows: abrasive type: white corundum abrasive, abrasive particle size: 80 mesh, air pressure: 0.40MPa, sandblasting distance: 80mm, sandblasting angle: 60°~75°.

[0073] A 125±25μm MCrAlY undercoat was applied to the blade edge plate using supersonic flame spraying. The spraying parameters were: oxygen pressure 150±10PSI, oxygen flow rate 1200±50SCFH, fuel pressure 120±10PSI, fuel flow rate 7.0±2SCFH, powder feed rate 110g / min, spraying distance 360mm, and spraying angle 75°~90°.

[0074] A 250±50μm YSZ surface layer was applied to the blade edge plate using plasma spraying. The spraying process parameters were: main gas Ar flow rate 40±5NLPM, secondary gas H2 flow rate 15±2NLPM, current 550±10A, powder feeding rate 80±10g / min, spraying distance 100mm, and spraying angle 75°~90°.

[0075] Physical vapor deposition (PVD) was used to protect the rim plates of the turbine guide vanes. The blade body underwent wet sandblasting, followed by ultrasonic cleaning, acetone immersion, and drying. The wet sandblasting process parameters were: white corundum alumina particle size of 230 mesh, corundum alumina content of 20±10%, air pressure of 0.15±0.2 MPa, and sandblasting distance of 200 mm.

[0076] A 60±5μm MCrAlY underlayer was coated using vacuum arc plating. The ion cleaning process parameters were: bias voltage U = 500V, arc current I = 70A±2A, duty cycle D = 40%. The deposition process parameters were: bias voltage U = 250V, arc current I = 70A±2A, duty cycle D = 20%.

[0077] A 150 μm YSZ ceramic surface layer was prepared using electron beam physical vapor deposition. The ion cleaning process parameters were: argon pressure P = 0.05 MPa, argon flow rate L = 37 ml / min, and cleaning time t = 10 min ± 2. The deposition process parameters were: main vacuum chamber pressure not exceeding 1.0 × 10⁻⁶ m² / min. -3 The torr electron gun voltage is 17kV~20kV, the target heating current is 1.2A~1.5A, the workpiece rotation speed is 15r / min, the substrate temperature is 950℃, and the oxygen flow rate is 200±10ml / min.

[0078] The final thermal barrier coating structure of the turbine guide vane edge plate is a layered structure, while the thermal barrier coating structure of the blade body is a columnar crystalline structure.

[0079] Example 5

[0080] The turbine guide vane was protected by a spraying fixture, and the blade edge plate surface was treated with dry sandblasting. The dry sandblasting process parameters were as follows: abrasive type: white corundum abrasive, abrasive particle size: 80 mesh, air pressure: 0.40MPa, sandblasting distance: 100mm, sandblasting angle: 60°~75°.

[0081] A 125±25μm MCrAlY undercoat was applied to the blade edge plate using supersonic flame spraying. The spraying parameters were: oxygen pressure 150±10PSI, oxygen flow rate 1200±50SCFH, fuel pressure 120±10PSI, fuel flow rate 7.0±2SCFH, powder feed rate 110g / min, spraying distance 360mm, and spraying angle 75°~90°.

[0082] A 250±50μm YSZ surface layer was applied to the blade edge plate using plasma spraying. The spraying process parameters were: main gas Ar flow rate 40±5NLPM, secondary gas H2 flow rate 15±2NLPM, current 550±10A, powder feeding rate 80±10g / min, spraying distance 100mm, and spraying angle 75°~90°.

[0083] Physical vapor deposition (PVD) was used to protect the rim plates of the turbine guide vanes. The blade body underwent wet sandblasting, followed by ultrasonic cleaning, acetone immersion, and drying. The wet sandblasting process parameters were: white corundum alumina particle size of 230 mesh, corundum alumina content of 20±10%, air pressure of 0.15±0.2 MPa, and sandblasting distance of 250 mm.

[0084] A 60±5μm MCrAlY underlayer was coated using vacuum arc plating. The ion cleaning process parameters were: bias voltage U = 600V, arc current I = 70A±2A, duty cycle D = 40%. The deposition process parameters were: bias voltage U = 250V, arc current I = 70A±2A, duty cycle D = 20%.

[0085] A 100 μm YSZ ceramic surface layer was prepared using electron beam physical vapor deposition. The ion cleaning process parameters were: argon pressure P = 0.05 MPa, argon flow rate L = 37 ml / min, and cleaning time t = 10 min ± 2. The deposition process parameters were: main vacuum chamber pressure not exceeding 1.0 × 10⁻⁶ m² / min. -3 The torr electron gun voltage is 17kV~20kV, the target heating current is 1.2A~1.5A, the workpiece rotation speed is 15r / min, the substrate temperature is 900℃, and the oxygen flow rate is 200±10ml / min.

[0086] The final thermal barrier coating structure of the turbine guide vane edge plate is a layered structure, while the thermal barrier coating structure of the blade body is a columnar crystalline structure.

[0087] Example 6

[0088] The turbine guide vane was protected by a spraying fixture, and the blade edge plate surface was treated with dry sandblasting. The dry sandblasting process parameters were as follows: abrasive type: white corundum abrasive, abrasive particle size: 80 mesh, air pressure: 0.40MPa, sandblasting distance: 150mm, sandblasting angle: 60°~75°.

[0089] A 125±25μm MCrAlY undercoat was applied to the blade edge plate using supersonic flame spraying. The spraying parameters were: oxygen pressure 150±10PSI, oxygen flow rate 1200±50SCFH, fuel pressure 120±10PSI, fuel flow rate 7.0±2SCFH, powder feed rate 110g / min, spraying distance 360mm, and spraying angle 75°~90°.

[0090] A 250±50μm YSZ surface layer was applied to the blade edge plate using plasma spraying. The spraying process parameters were: main gas Ar flow rate 40±5NLPM, secondary gas H2 flow rate 15±2NLPM, current 550±10A, powder feeding rate 80±10g / min, spraying distance 100mm, and spraying angle 75°~90°.

[0091] Physical vapor deposition (PVD) was used to protect the rim plates of the turbine guide vanes. The blade body underwent wet sandblasting, followed by ultrasonic cleaning, acetone immersion, and drying. The wet sandblasting process parameters were: white corundum alumina particle size of 230 mesh, corundum alumina content of 20±10%, air pressure of 0.15±0.2 MPa, and sandblasting distance of 250 mm.

[0092] A 60±5μm MCrAlY underlayer was coated using vacuum arc plating. The ion cleaning process parameters were: bias voltage U = 700V, arc current I = 70A±2A, duty cycle D = 40%. The deposition process parameters were: bias voltage U = 250V, arc current I = 70A±2A, duty cycle D = 20%.

[0093] A 200 μm YSZ ceramic surface layer was prepared using electron beam physical vapor deposition. The ion cleaning process parameters were: argon pressure P = 0.05 MPa, argon flow rate L = 37 ml / min, and cleaning time t = 10 min ± 2. The deposition process parameters were: main vacuum chamber pressure not exceeding 1.0 × 10⁻⁶ m² / min. -3 The torr electron gun voltage is 17kV~20kV, the target heating current is 1.2A~1.5A, the workpiece rotation speed is 15r / min, the substrate temperature is 950℃, and the oxygen flow rate is 200±10ml / min.

[0094] The final thermal barrier coating structure of the turbine guide vane edge plate is a layered structure, while the thermal barrier coating structure of the blade body is a columnar crystalline structure.

[0095] Comparative Example 1

[0096] This scheme employs physical vapor deposition (PVD) to prepare thermal barrier coatings for turbine guide vanes. First, the blade body and shrouds undergo wet sandblasting, followed by ultrasonic cleaning, acetone immersion, and drying. The wet sandblasting process parameters are: white corundum alumina particle size of 230 mesh, corundum alumina content of 20±10%, air pressure of 0.15±0.2 MPa, and sandblasting distance of 250 mm.

[0097] A 60±5μm MCrAlY underlayer was coated using vacuum arc plating. The ion cleaning process parameters were: bias voltage U = 700V, arc current I = 70A±2A, duty cycle D = 40%. The deposition process parameters were: bias voltage U = 250V, arc current I = 70A±2A, duty cycle D = 20%.

[0098] A 200 μm YSZ ceramic surface layer was prepared using electron beam physical vapor deposition. The ion cleaning process parameters were: argon pressure P = 0.05 MPa, argon flow rate L = 37 ml / min, and cleaning time t = 10 min ± 2. The deposition process parameters were: main vacuum chamber pressure not exceeding 1.0 × 10⁻⁶ m² / min. -3 The electron gun voltage was 17kV–20kV, the target heating current was 1.2A–1.5A, the workpiece rotation speed was 15r / min, the substrate temperature was 950℃, and the oxygen flow rate was 200±10ml / min. A columnar thermal barrier coating with a thickness of 260μm was finally prepared.

[0099] Comparative Example 2

[0100] This scheme uses thermal spraying to prepare the thermal barrier coating for turbine guide vanes. First, the blade body and edge plate surfaces are subjected to dry sandblasting treatment. The dry sandblasting process parameters are: abrasive type: white corundum abrasive, abrasive particle size: 80 mesh, air pressure: 0.40MPa, sandblasting distance: 150mm, sandblasting angle: 60°~75°.

[0101] A 125±25μm MCrAlY undercoat was applied to the blade edge plate using supersonic flame spraying. The spraying parameters were: oxygen pressure 150±10PSI, oxygen flow rate 1200±50SCFH, fuel pressure 120±10PSI, fuel flow rate 7.0±2SCFH, powder feed rate 110g / min, spraying distance 360mm, and spraying angle 75°~90°.

[0102] A 250±50μm YSZ surface layer was plasma-sprayed onto the blade edge. The spraying parameters were: main gas Ar flow rate 40±5 NLPM, secondary gas H2 flow rate 15±2 NLPM, current 550±10A, powder feed rate 80±10 g / min, spraying distance 100mm, and spraying angle 75°~90°. A layered thermal barrier coating with a thickness of 400μm was ultimately prepared.

[0103] The porosity of the coatings obtained in Comparative Example 1 and Comparative Example 2 was analyzed by metallographic microscopy after inlay polishing. According to relevant testing standards, the bonding strength of thermal barrier coatings with different microstructures and the thermal cycle life of the coatings at 1100℃ were tested and analyzed. In the thermal cycle life test, the coating failure was defined as the area of ​​coating peeling exceeding 10%.

[0104] The thermal conductivity of the coating is obtained from the coating density, specific heat capacity, and thermal diffusivity.

[0105] λ=α·Cp·ρ (1)

[0106] In the formula, λ is the thermal conductivity, with units of W / (m·K); α is the thermal diffusivity, with units of mm. 2 / s; Cp is the specific heat capacity at constant pressure, in J / g·K; ρ is the density, in g / cm³. 3 .

[0107] The test results are as follows:

[0108] Typical metallographic structures of thermal barrier coatings prepared by thermal spraying include: Figure 6 As shown, the typical metallographic structure of thermal barrier coatings prepared by physical vapor deposition is as follows: Figure 7 .

[0109] The porosity of the ceramic layers was analyzed using metallographic methods, and the testing standard was in accordance with HB 20195-2014 "Metallographic Inspection of Thermally Sprayed Coatings". According to the standard requirements, porosity is the proportion of pores or cracks in the coating to the measured area. The measured porosity of the YSZ coating prepared by plasma spraying was 8.2%, and the porosity of YSZ prepared by electron beam physical vapor deposition was 18.3%. The figures show that the YSZ ceramic surface layer prepared by thermal spraying exhibits a layered structure, while the YSZ ceramic surface layer prepared by electron beam physical vapor deposition exhibits a columnar crystalline structure.

[0110] The tensile bond strength of the coating samples was tested using the pull-out method, and the test standard was based on AETF 68A "Tensile Bond Strength Test Method for Coatings". The results are shown in the table below. It can be seen from the table that the tensile bond strength of the thermal barrier coating prepared by physical vapor deposition is significantly better than that of the thermal barrier coating prepared by thermal spraying.

[0111] Table 1. Test results of bonding strength of thermal barrier coatings

[0112]

[0113] Following the AETF58A method for thermal cycling tests on coatings, the coating was deemed to have failed when it was held at 1100℃ for 55 minutes followed by 5 minutes of air cooling until the peeling area exceeded 20%. The lifetimes of thermal barrier coatings prepared by thermal spraying and physical vapor deposition were compared. The results showed that the lifetime of the thermally sprayed coating was 617 hours, while the lifetime of the physical vapor deposition coating was 1025 hours.

[0114] The thermal conductivity of thermal barrier coatings prepared by the two processes was measured according to the MAS1255B thermal barrier coating thermal conductivity test method. The results are as follows:

[0115] Table 2. Thermal conductivity of thermal barrier coatings prepared by different processes (W / (m·K))

[0116]

[0117] The table shows that the thermal conductivity of thermal barrier coatings prepared by thermal spraying is significantly lower than that of thermal barrier coatings prepared by physical vapor deposition, meaning that thermal barrier coatings prepared by thermal spraying have better thermal insulation performance.

[0118] In summary, physical vapor deposition (PVD) thermal barrier coatings are superior to thermal spray coatings in terms of coating bonding strength and resistance to thermal cycling. However, thermal spray coatings are superior to PVD coatings in terms of coating porosity and insulation performance. Therefore, we designed the guide vane edge plate, which requires good insulation, with a thermal spray coating, and the blade body, which requires high bonding strength, with a PVD coating. This combines the advantages of both processes and achieves the goal of long-life blade operation.

Claims

1. A thermal barrier coating for turbine guide vanes, characterized in that, It consists of an MCrAlY base layer and a YSZ ceramic surface layer. The MCrAlY base layer is composed of 18%~23% Cr, 9%~13.5% Al, 0.6%~1.2% Y, and the remainder is Ni by mass percentage. The YSZ ceramic surface layer is composed of Zr2O3 doped with 6%~9% Y2O3 by mass percentage. The thermal barrier coating is divided into a thermal barrier coating at the blade edge and a thermal barrier coating at the blade body. The thermal barrier coating at the blade edge is applied by spraying the MCrAlY base layer with a supersonic flame and the YSZ ceramic surface layer with a plasma spraying method. The thermal barrier coating at the blade body is applied by multi-arc ion plating of the MCrAlY base layer and electron beam physical vapor deposition of the YSZ ceramic surface layer. The thermal barrier coating at the edge plate has a layered structure with a porosity of 6% to 10%; the thermal conductivity of the coating at 1100℃ is 1.212 W / (m·K) to 1.294 W / (m·K). The thermal barrier coating on the blade has a columnar crystalline structure. The method for preparing the thermal barrier coating for turbine guide vanes includes the following steps: Step 1. Protect the blade body of the turbine guide vanes with tooling; Step 2. Dry sandblasting treatment of the turbine guide vane rim surface; Step 3. Prepare the MCrAlY underlayer for the edging plate using a supersonic flame spraying process; Step 4. Prepare the YSZ ceramic surface layer of the edging plate using plasma spraying process; Step 5. Tool the rim of the turbine guide vanes for protection; Step 6. Perform wet sandblasting on the turbine guide vane blades to activate the surface of the parts; Step 7. Prepare the MCrAlY underlayer for the blade using a multi-arc ion plating process; Step 8. Electron beam physical vapor deposition is used to deposit a YSZ ceramic surface layer on the blade; In particular, the tooling protection in steps 1 and 5 both adopt automated spraying tooling; In step 8, the substrate temperature is 900°C~950°C.

2. The thermal barrier coating for turbine guide vanes according to claim 1, characterized in that, The thermal barrier coating of the flange has an MCrAlY bottom layer thickness of 100μm~150μm and a YSZ ceramic top layer thickness of 200μm~300μm.

3. The thermal barrier coating for turbine guide vanes according to claim 1, characterized in that, The thickness of the MCrAlY underlayer in the blade thermal barrier coating is 40μm~70μm, and the thickness of the YSZ ceramic surface layer is 100μm~200μm; Its resistance to thermal cycling at 1100℃ is more than 50% higher than that of layered structures of the same thickness.

4. A thermal barrier coating for turbine guide vanes according to claim 1, characterized in that, In step 2, during the dry sandblasting process, the abrasive used for sandblasting is white corundum abrasive with a particle size of 36-80 mesh, an air pressure of 0.20MPa-0.40MPa, a sandblasting distance of 80mm-150mm, and a sandblasting angle of 60°-75°.

5. A thermal barrier coating for turbine guide vanes according to claim 1, characterized in that, In step 3, the process parameters for supersonic flame spraying are: oxygen pressure 150 ±10 PSI, oxygen flow rate 1200 ±50 SCFH, fuel pressure 120 ±10 PSI, fuel flow rate 7.0 ±2 SCFH, powder feeding rate 120 g / min ~130 g / min, spraying distance 350 mm ~370 mm, and spraying angle 75° ~90°.

6. A thermal barrier coating for turbine guide vanes according to claim 1, characterized in that, In step 4, the process parameters for plasma spraying are as follows: the main gas is Ar, with a flow rate of 40±5 NLPM; the secondary gas is H2, with a flow rate of 15±2 NLPM; the current is 550±10 A; the powder feeding rate is 80±10 g / min; the spraying distance is 90 mm~110 mm; and the spraying angle is 75°~90°.

7. A thermal barrier coating for turbine guide vanes according to claim 1, characterized in that, In step 6, the process parameters for wet sand blowing are as follows: the abrasive is white corundum sand with a particle size of 180 mesh to 230 mesh; the white corundum sand content is 20±10%; the air pressure is 0.15±0.2 MPa; and the sand blowing distance is 180mm to 250mm. After the wet sandblasting is completed, the leaf blades need to be ultrasonically cleaned with deionized water, immersed in acetone solution, and dried in sequence.

8. A thermal barrier coating for turbine guide vanes according to claim 1, characterized in that, In step 7, the multi-arc ion plating process mainly includes an ion cleaning process and a deposition process; wherein the parameters of the ion cleaning process are: bias voltage U = 500 V~700 V, arc current I = 70 A ± 2 A, duty cycle D = 25%~45%; the parameters of the deposition process are: bias voltage U = 200 V~275 V, arc current I = 70 A ± 2 A, duty cycle D = 10%~30%.

9. A thermal barrier coating for turbine guide vanes according to claim 1, characterized in that, In step 8, electron beam physical vapor deposition includes an ion cleaning process and a deposition process; wherein, the ion cleaning process parameters are: argon pressure P = 0.04 MPa~0.06 MPa, argon flow rate L = 36 ml / min~38 ml / min, and cleaning time t = 10 ± 2 min; the deposition process parameters are: main vacuum chamber pressure not greater than 1.0 × 10⁻⁶. -3 The torr electron gun voltage is 17kV ~ 20kV, the target heating current is 1.2A ~ 1.5A, the workpiece rotation speed is 15r / min, and the oxygen flow rate is 200±10 ml / min.

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