Corrosion-resistant and low-radiation characteristic integrated coating for turbine blade and preparation method of corrosion-resistant and low-radiation characteristic integrated coating

Abstract

The invention belongs to the technical field of aero-engine coatings, and particularly relates to a turbine blade corrosion-resistant and low-radiation characteristic integrated coating and a preparation method thereof.The coating is composed of a multi-arc ion plating AlSi coating with good oxidation corrosion resistance and a Cr2AlC low-emissivity surface layer with the low-radiation characteristic; the manufacturing method of the pattern layer mainly comprises the following steps: firstly, carrying out wet sand blasting pretreatment on the turbine blade; then the turbine blade is subjected to ultrasonic cleaning and blow-drying, then the turbine blade is subjected to immersion cleaning with an alcohol-acetone mixed solution, and then blow-drying is conducted; and finally, an AlSi metal bonding bottom layer and a Cr2AlC low-emissivity surface are prepared through a multi-arc ion plating technology, and vacuum annealing is conducted on the turbine blade. The coating technology is simple, only two layers are included, coating deposition can be achieved through a single furnace, and frequent discharging is needed in the preparation process, so that the reliability of the coating technology is affected. In addition, the low-emissivity surface layer of the coating is a ceramic layer, the wear resistance is better compared with an existing precious metal surface layer, and long-life service is achieved.

Description

Technical Field

[0001] The present invention belongs to the technical field of aviation engine coatings, and in particular relates to a turbine blade coating with integrated corrosion resistance and low radiation characteristics and a preparation method thereof. Background Art

[0002] Low radiation characteristics are the iconic technical indicators of advanced aircraft. Aircraft engines are the power source of aircraft and also the largest radiation source, accounting for more than 90%. Its infrared radiation energy comes from the radiation of the high-temperature solid wall (such as nozzle, afterburner, low-pressure turbine, etc.) and the high-temperature tail jet at the rear of the engine, as well as the cavity radiation formed by the two. It is mainly concentrated in the 3μm-5μm wavelength range, which is the main tracking target band for infrared guided missiles. Due to the clean background at high altitude and the much lower ambient temperature than the engine temperature, the engine radiation characteristics appear extremely obvious against the sky background. Turbine blades, as rear-view visible components, are the main radiation signal source of aircraft engines. In order to simultaneously meet the requirements of turbine blades for anti-oxidation corrosion and low-radiation signal characteristics, their surfaces need to be coated with corrosion-resistant and low-signature integrated coatings. This coating has the characteristics of strong adaptability to the target shape and little impact on the maneuverability of the equipment. It is a key technology for aircraft engines to achieve low-radiation target characteristics.

[0003] On the other hand, the service environment of turbine blades is harsh, and they need to withstand centrifugal loads, high-temperature and high-speed gas loads, etc. The alloy matrix alone can no longer meet the service conditions. In order to improve the service life and reliability of parts, protective coatings are applied to their surfaces without exception. The existing corrosion-resistant coatings for turbine blades adopt silicon-modified aluminide coatings. Silicon-modified aluminide coatings have excellent resistance to high-temperature oxidation corrosion and have been widely used on the surface of low-pressure turbine blades of aircraft engines. At present, this type of coating is prepared by the slurry method, that is, the slurry composed of aluminum, silicon or aluminum-silicon alloy powder and liquid organic / inorganic salt as a binder and activator is applied to the blade surface by air spraying, and then dried and high-temperature diffusion treatment is performed to prepare the aluminum-silicon coating. The storage period of the slurry prepared by this method is generally no more than 1 year, and it is often prepared and used immediately. Typical brands of aluminum-silicon slurries at home and abroad include Sermaloy J, WL-1, SKAS-3, etc. The production cycle of aluminum-silicon coatings prepared by the slurry method is long, the production efficiency is low, the coating thickness is completely dependent on the manual control of workers during the coating slurry process, and the product quality consistency and stability are poor.

[0004] At present, the corrosion-resistant and low-signature integrated coating of turbine blades is composed of multiple layers of coatings. First, the aluminum silicon coating is prepared by the slurry process, and then the low-radiation characteristic coating composed of a bonding layer matching the aluminum silicon coating, an oxide intermediate layer to prevent diffusion, and a low-radiation signal precious metal surface layer is prepared by the magnetron sputtering process or air spraying. The process needs to be turned back and forth, which is easy to cause interface contamination problems during the production process. The coating will peel off after a short service time, affecting the reliability and low target characteristics of the coating. In addition, the precious metal surface layer has poor wear resistance and is prone to scratch damage during service.

[0005] From the above, it can be seen that the surface coating of turbine blades needs to have both corrosion resistance and low target characteristic functions. High temperature and high speed gas scouring, heat load, extremely variable speed working conditions and complex and harsh working environment as well as long life and high reliability requirements bring great difficulties and challenges to the application of low vortex blade corrosion resistant low target characteristic integrated coating. Summary of the invention

[0006] Based on the above problems, the purpose of the present invention is to provide a turbine blade corrosion-resistant and low-radiation integrated coating and preparation method. The coating is prepared entirely by multi-arc ion plating process, which avoids interface contamination caused by frequent furnace discharge and improves the reliability and production efficiency of the coating.

[0007] The technical solution adopted by the present invention is: a turbine blade corrosion-resistant and low-radiation characteristic integrated coating, the coating is composed of a Cr2AlC low-radiation surface layer with low-radiation characteristics and an AlSi metal bonding bottom layer with oxidation and corrosion resistance, the thickness of the AlSi metal bonding bottom layer is 20μm~40μm, and the thickness of the Cr2AlC low-radiation surface layer is 4μm~8μm;

[0008] The coating preparation method comprises the following steps:

[0009] Step 1: Pre-treat the turbine blades by wet sandblasting, and use a strong water flow to remove the residual aluminum oxide particles on the surface of the turbine blades after wet sandblasting;

[0010] Step 2: Ultrasonic cleaning of the turbine blades and then drying;

[0011] Step 3: Use an alcohol-acetone mixed solution to clean the turbine blades, then blow dry;

[0012] Step 4: Prepare the AlSi metal bonding bottom layer and the Cr2AlC low emissivity surface layer by using a multi-arc ion plating process, which specifically includes the following steps:

[0013] Step 4.1: Place the turbine blade into the multi-arc ion plating equipment using a coating tool with a rotating function;

[0014] Step 4.2: Evacuate and heat the turbine blades;

[0015] Step 4.4: Deposition of AlSi coating;

[0016] Step 4.5: Deposition of Cr2AlC coating;

[0017] Step 5: Vacuum annealing of the turbine blades.

[0018] The beneficial effects of the present invention are as follows: the coating process is simple, consisting of only two layers, and the coating deposition can be achieved in a single furnace, while the existing technology has a four-layer structure, and the coating needs to be frequently removed from the furnace during the preparation process, which affects the reliability of the coating process. In addition, the low-emissivity surface layer of the coating is a ceramic layer, which has better wear resistance than the existing precious metal surface layer, and can achieve long service life. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a flow chart of a method for manufacturing a coating integrating corrosion resistance and low radiation characteristics for turbine blades according to the present invention;

[0020] Figure 2 This is a schematic diagram of the structure of the special coating device for turbine blades proposed by the present invention;

[0021] Figure 3 A schematic diagram of the spectral emissivity measurement results of the coating prepared in the present invention at 80°C;

[0022] Figure 4 A schematic diagram of the emissivity measurement results of the coating prepared in the present invention at 900°C; DETAILED DESCRIPTION

[0023] The present invention is described in detail below in conjunction with the accompanying drawings, but the protection scope of the present invention is not limited by the embodiments.

[0024] First, in order to meet the requirements of integrating corrosion resistance and low radiation characteristics of turbine blades, the present invention provides a coating integrating corrosion resistance and low radiation characteristics of turbine blades, wherein the coating consists of a Cr2AlC low-emissivity surface layer with low radiation characteristics and an AlSi metal bonding bottom layer with anti-oxidation and corrosion performance; wherein the thickness of the AlSi metal bonding bottom layer is 20μm~40μm, and the thickness of the Cr2AlC ceramic insulation surface layer is 4μm~8μm.

[0025] Secondly, if Figure 1 As shown, the present invention also provides a method for manufacturing a turbine blade corrosion-resistant and low-radiation characteristic integrated coating, comprising the following steps:

[0026] Step 1: Pre-treat the turbine blades by wet sandblasting, and use a strong water flow to remove the residual aluminum oxide particles on the surface of the turbine blades after wet sandblasting;

[0027] The specific process parameters of wet sand blowing include: 180#~250# white corundum, 0.25MP~0.35MPa wind pressure, water pressure greater than 0.2MPa, sand blowing distance of 180mm~350mm, and angle of 60°~90°.

[0028] Step 2: Ultrasonic cleaning of the turbine blades and then drying;

[0029] Specifically, in this embodiment, an ultrasonic cleaning machine can be used to perform ultrasonic cleaning on the turbine blades to remove floating dust and sand on the surface of the parts. The ultrasonic cleaning solution is deionized water, the frequency F=20kHz, the output voltage U=320V~370V, and the cleaning time: 10min~15min;

[0030] During ultrasonic cleaning, the turbine blades should be completely immersed in deionized water with the surface to be coated facing downward.

[0031] In addition, the deionized water used for ultrasonic cleaning should be turned on the ultrasonic cleaning machine and visually inspected before each cleaning. If there are impurities or dirt, replace it immediately;

[0032] After ultrasonic cleaning, the turbine blades are blown dry with water-free and oil-free compressed air.

[0033] Step 3: Use an alcohol-acetone mixed solution to clean the turbine blades, then blow dry;

[0034] Specifically, in this embodiment, the turbine blades are first evenly spread in a container, and then immersed in the alcohol-acetone mixed solution, the mass ratio of alcohol to acetone is 3:1, the solution should completely cover the workpiece, and the immersion time is: 10min~20min;

[0035] After the washing, the turbine blades are blown dry with water-free and oil-free compressed air, and then placed in a clean tray and dried at 100℃~150℃ for 20min~30min.

[0036] Step 4: Prepare the AlSi metal bonding bottom layer and the Cr2AlC ceramic insulation surface layer by using a multi-arc ion plating process, which specifically includes the following steps:

[0037] Step 4.1: Place the turbine blade into a multi-arc ion plating device using a special coating device for turbine blades with a rotating function;

[0038] Among them, the structure of the special coating device for turbine blades is as follows Figure 2 As shown, during the clamping process, avoid touching the turbine blades to prevent contamination of the turbine blades;

[0039] Step 4.2: Evacuate and heat the turbine blades;

[0040] When the vacuum degree is ≤3×10-3 Pa, stop when the temperature of turbine blades reaches 200℃~250℃;

[0041] Step 4.3: Perform argon ion cleaning on the turbine blades to remove contaminants attached to the surface of the parts;

[0042] The specific parameters of argon ion cleaning are: bias voltage = -600V~-800V, argon ion flow rate = 500sccm~800sccm, grating angle = 5°~10°, vacuum chamber pressure: 2Pa~4Pa, which can be achieved by adjusting the argon ion flow rate, duty cycle = 40%, and cleaning time is 3min~5min;

[0043] Step 4.4: Deposition of AlSi coating;

[0044] The composition of AlSi target is Al-9w.t.%Si. He is introduced as working gas. The vacuum chamber pressure is controlled at 3Pa~6Pa by adjusting the gas flow. After the vacuum chamber pressure is stable, the bias voltage is -450V~-500V, the duty cycle is 50%~60%, the arc current is 180A~200A, and the blade irradiation power is 8.5×10 4 W~9.5×10 4 W, turn off the arc source, bias and He after deposition for 40min~50min.

[0045] Step 4.5: Deposition of Cr2AlC coating;

[0046] Use a special coating device for turbine blades to rotate the turbine blades to the front of the Cr2AlC target, introduce high-purity Ar gas, and control the vacuum chamber pressure at 0.3Pa~0.6Pa by adjusting the gas flow rate. After the vacuum chamber pressure stabilizes, the bias voltage is -100V~-300V, the duty cycle is 20%~40%, the arc current is 180A~200A, and after deposition for 60min~120min, the arc source, bias voltage, and gas valve are turned off in turn. When the temperature in the vacuum chamber drops below 100℃, take out the blade.

[0047] Step 5: vacuum annealing the turbine blades;

[0048] Specifically, the taken out turbine blades are placed in a corundum crucible, one piece per can, covered with a corundum lid, and placed in a vacuum annealing furnace for crystallization annealing treatment at 870°C for 2h~4h. The heating rate should be controlled at 8°C / min~12°C / min. Cool with the furnace. When the furnace temperature drops below 200°C, open the furnace door and take out the blades.

[0049] The above steps can complete the process of manufacturing the integrated coating with corrosion resistance and low radiation characteristics for turbine blades.

[0050] from Figure 3 and Figure 4 It can be seen that the corrosion-resistant and low-radiation integrated coating made for turbine blades by the above method has low spectral emissivity for radiation waves with wavelengths of 3μm~5μm and 8μm~14μm at temperatures of 80°C and 900°C respectively.

Claims

1. A turbine blade corrosion-resistant and low-radiation integrated coating, characterized in that: The coating consists of a Cr2AlC low-emissivity surface layer with low radiation characteristics and an AlSi metal bonding bottom layer with anti-oxidation and corrosion performance. The thickness of the AlSi metal bonding bottom layer is 20μm~40μm, and the thickness of the Cr2AlC low-emissivity surface layer is 4μm~8μm.

2. A method for manufacturing a turbine blade corrosion-resistant and low-radiation integrated coating according to claim 1, characterized in that: The following steps are involved: Step 1: Pre-treat the turbine blades by wet sandblasting; Step 2: Ultrasonic cleaning of the turbine blades and then drying; Step 3: Use an alcohol-acetone mixed solution to clean the turbine blades, then blow dry; Step 4: Prepare the AlSi metal bonding bottom layer and the Cr2AlC low emissivity surface layer by using a multi-arc ion plating process, which specifically includes the following steps: Step 4.1: Place the turbine blade into the multi-arc ion plating equipment using a coating tool with a rotating function; Step 4.2: Evacuate and heat the turbine blades; Step 4.3: Perform argon ion cleaning on turbine blades; Step 4.4: Deposition of AlSi coating; Step 4.5: Deposition of Cr2AlC coating; Step 5: Vacuum annealing of the turbine blades.

3. The method for manufacturing a turbine blade corrosion-resistant and low-radiation integrated coating according to claim 2, characterized in that: The specific process parameters of wet sand blowing in step 1 include: 180#~250# white corundum, 0.25MPa~0.35MPa wind pressure, water pressure greater than 0.2MPa, sand blowing distance of 180 mm~350mm, and angle of 60°~90°.

4. The method for manufacturing a turbine blade corrosion-resistant and low-radiation integrated coating according to claim 2, characterized in that: In the step 2, the ultrasonic cleaning solution is deionized water, the frequency F=20kHz, the output voltage U=320V~370V, and the cleaning time is: 10 min~15 min.

5. The method for manufacturing a turbine blade corrosion-resistant and low-radiation integrated coating according to claim 2, characterized in that: In step 3, the mass ratio of alcohol to acetone in the alcohol-acetone mixed solution is 3:1, the alcohol-acetone mixture should completely cover the workpiece, and the immersion time is 10 min to 20 min; After the turbine blades have been washed, they are blown dry with water-free and oil-free compressed air, and then placed in a clean tray and dried at 100°C to 150°C for 20 min to 30 min.

6. The method for manufacturing a turbine blade corrosion-resistant and low-radiation integrated coating according to claim 2, characterized in that: In step 4.2, when the vacuum degree is ≤3×10 -3 Pa and the temperature of the turbine blades reaches 200℃~250℃ and stops.

7. The method for manufacturing the turbine blade corrosion-resistant and low-radiation integrated coating according to claim 3, characterized in that: The specific parameters of the argon ion cleaning in step 4.3 are: bias voltage = -600V~-800V, argon ion flow rate = 500sccm~800sccm, grating angle = 5°~10°, vacuum chamber pressure: 2Pa~4Pa, duty cycle = 40%, and cleaning time is 3min~5min.

8. The method for manufacturing a turbine blade corrosion-resistant and low-radiation integrated coating according to claim 2, characterized in that: In step 4.4, the composition of the AlSi target material is Al-9w.t.%Si, He is introduced as the working gas, and the vacuum chamber pressure is controlled at 3Pa~6Pa by adjusting the gas flow rate. After the vacuum chamber pressure is stable, the bias voltage is -450V~-500V, the duty cycle is 50%~60%, the arc current is 180A~200A, and the leaf irradiation power is 8.5×10 4 W~9.5×10 4 W, turn off the arc source, bias and He after deposition for 40min~50min.

9. The method for manufacturing a turbine blade corrosion-resistant and low-radiation integrated coating according to claim 2, characterized in that: The step 4.5 comprises: using a special coating device for turbine blades to rotate the turbine blades to the front of the Cr2AlC target, introducing high-purity Ar gas, controlling the vacuum chamber pressure at 0.3Pa~0.6Pa by adjusting the gas flow rate, and after the vacuum chamber pressure stabilizes, when the bias voltage is -100V~-300V, the duty cycle is 20%~40%, the arc current is 180A~200A, and after deposition for 60min~120min, the arc source, bias voltage, and gas valve are closed in sequence, and the temperature in the vacuum chamber drops below 100°C, and the blade is taken out.

10. The method for manufacturing a turbine blade corrosion-resistant and low-radiation integrated coating according to claim 2, characterized in that: The step 5 comprises: placing the taken out turbine blades into a corundum crucible, one piece per can, covering with a corundum lid, placing in a vacuum annealing furnace for crystallization annealing treatment at 870°C for 2h~4h, the heating rate should be controlled at 8°C / min~12°C / min, cooling with the furnace, and when the furnace temperature drops below 200°C, opening the furnace door and taking out the blades.

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