Preparation method of thermal barrier coating with bionic bamboo-like columnar crystal structure

Abstract

The invention relates to the technical field of aero-engine thermal barrier coatings, in particular to a preparation method of a bionic bamboo-like columnar crystal structure thermal barrier coating. According to the method, in the electron beam physical vapor deposition process, periodic control over guide airflow and electron beam current is added, the columnar crystal growth process and the microstructure are effectively controlled, and the thermal barrier coating of the bionic bamboo-joint-shaped columnar crystal structure is obtained. The bamboo-like structure coating prepared in the invention has low thermal conductivity and good high-temperature thermal shock life.

Description

Technical Field

[0001] This invention belongs to the field of thermal barrier coating technology for aero-engines, and relates to a method for preparing a biomimetic bamboo-like columnar crystal structure thermal barrier coating. Background Technology

[0002] Thermal barrier coatings (TBCs), as one of the three key technologies for aero-engine turbine blades, can effectively improve the temperature resistance of turbine blades, thereby increasing engine thrust and operating efficiency. TBCs mainly consist of two parts: a metal bonding layer and a ceramic surface layer. The metal bonding layer has excellent oxidation resistance and serves to connect the substrate and the ceramic surface layer; currently, the MCrAlY system is the primary choice. The ceramic surface layer has excellent thermal insulation capabilities and acts as the thermal insulation layer of the TBC; a classic ceramic surface layer material is yttrium-stabilized zirconia (YSZ) ceramic.

[0003] Currently, the main technologies for preparing thermal barrier coating ceramic surfaces include atmospheric plasma spraying (APS) and electron beam physical vapor deposition (EB-PVD). Thermal barrier coatings prepared by atmospheric plasma spraying have a layered structure and good thermal insulation performance, but their strain tolerance is poor. During the service of engine turbine rotor blades, due to the high temperature and high speed service conditions, the large deformation of the substrate causes large thermal stress to be generated between the substrate and the thermal barrier coating. The layered thermal barrier coating prepared by atmospheric plasma spraying will peel off and fail due to thermal stress.

[0004] Thermal barrier coatings prepared by EB-PVD process possess a unique columnar crystal arrangement structure with a large strain tolerance. During substrate deformation, the columnar crystal structure can alleviate thermal stress between the coating and the substrate, effectively extending the service life of the coating. However, due to the high thermal conductivity of the vertically aligned columnar crystal structure, the thermal insulation capacity of columnar crystal thermal barrier coatings is lower than that of lamellar structure thermal barrier coatings. The presence of gaps and pores between layers in lamellar structures can increase phonon scattering ability and reduce the phonon mean free path, thereby reducing thermal conductivity. In summary, introducing heterolayers or special structures into the columnar crystal structure to reduce the coating's thermal conductivity without compromising the high strain tolerance structure of the columnar crystals themselves has become one of the key problems that urgently need to be solved in thermal barrier coatings. Summary of the Invention

[0005] To address the problems of high thermal conductivity and poor thermal insulation performance in existing columnar crystalline thermal barrier coatings, the present invention aims to provide a method for preparing a biomimetic bamboo-like columnar crystalline thermal barrier coating. This method effectively increases the heat transfer barrier interface, reduces the thermal conductivity of the columnar crystalline thermal barrier coating, and maintains the high strain tolerance of the columnar crystalline structure, thus providing excellent thermal shock resistance.

[0006] To solve this technical problem, the technical solution of the present invention is as follows: A method for preparing a biomimetic bamboo-like columnar crystal structure thermal barrier coating includes the following steps: Step 1: Sandblast and clean the substrate surface; Step 2: Prepare a metal bonding layer on the substrate surface to obtain a sample. The preparation process can be one of plasma spraying, vacuum arc plating, or magnetron sputtering. Step 3: In the preparation of the ceramic surface layer, electron beam physical vapor deposition (EBPD) is used. A ceramic target for surface layer evaporation is selected, and the deposition temperature is controlled within a specific range to ensure stable growth of the ordered columnar crystal structure. The initial vacuum level is controlled at a high level to increase the perturbation effect of the guiding gas on the vapor cloud and columnar crystal growth. During deposition, a guiding gas flow is added to directly influence the vapor cloud flow. By periodically adjusting the electron beam current and guiding gas flow rate, a bamboo-like columnar crystal structure is constructed. The deposition time is 60-100 minutes. The periodic control process of the guiding gas flow rate and electron beam current is as follows: The first process involves 120-200 seconds of normal coating deposition without guiding gas flow, with an electron beam current of 1.4A~1.6A; the second process involves 20-30 seconds of gas flow rate and electron beam coupling control. This deposition process is repeated until the coating deposition is complete. In the second process, the gas flow rate and electron beam coupling control parameters are divided into three levels: First setting: Guide gas flow rate 55~65 sccm, electron beam current 1.18~1.22A; Second setting: Guide gas flow rate 75~85 sccm, electron beam current 1.23~1.27A; Third setting: Guide gas flow rate 95~105 sccm, electron beam current 1.33~1.37A.

[0007] The ceramic surface evaporation target in step three is a 7-20 wt% yttrium-stabilized zirconia (7-20 YSZ) ceramic target; different parameters are selected based on the composition of the ceramic surface target. When 16 < yttrium oxide content ≤ 20 wt%, select the third parameter level; When the yttrium oxide content is 11~16wt% (11~16YSZ), select the second parameter. When 7 ≤ yttrium oxide content < 11 wt%, select the first parameter level.

[0008] The deposition temperature for the three steps is 850℃~1000℃; The initial vacuum level of the deposition chamber in step three is <3×10⁻⁶. -2 Pa.

[0009] The matrix is ​​a nickel-based single-crystal high-temperature alloy, and the metal bonding layer is composed of one of NiPtAl, NiCoCrAlY, NiCrAlYSi, and NiCoCrAlYHf. The guiding gas in step three is a mixture of Ar and O2, with a flow rate ratio of 1:2. In step three, the angle between the guiding airflow and the horizontal plane of the crucible is 25±3°, the horizontal distance from the crucible is 200±20mm, and the vertical distance is 250±20mm; preferably, the angle is 25°, the horizontal distance from the crucible is 200mm, and the vertical distance is 250mm. In step three, the sample is positioned directly above the crucible, with a vertical distance of 300 ± 20 mm. Preferably, in step three, the sample is positioned directly above the crucible, with a vertical distance of 300 mm.

[0010] The plasma spraying process parameters in step two are as follows: spraying power: 20-60kW, spraying distance: 80-120mm, carrier gas composition: high-purity Ar or high-purity N2, carrier gas flow rate: 3-8L / min, powder feeding rate: 20-40g / min, substrate preheating temperature: 150-300℃.

[0011] The vacuum arc plating process parameters in step two are as follows: arc current: 500~600A, arc voltage: 20-40V, substrate bias voltage: 10~30V, vacuum degree: <1×10⁻⁶ -2 Pa, matrix temperature: 200-400℃.

[0012] The magnetron sputtering process parameters in step two are: 5-10 W / cm² 2 Working air pressure: 0.3-0.8Pa, substrate bias voltage: 80-100V, target-substrate distance: 80-100mm, substrate temperature: 200-350℃.

[0013] In step one, the sandblasting mode is dry sandblasting or water sandblasting, the sand particle type is Al2O3 sand particles or ZrO2 sand particles, the mesh size is 100-200 mesh, the sandblasting pressure is 0.2-0.4MPa, and the sandblasting time is 5-10min.

[0014] The cleaning process parameters in step one are as follows: cleaning solvent: anhydrous ethanol, analytical grade; cleaning time: 15-20 min; drying temperature: 60-90℃; drying time: 20-30 min.

[0015] The beneficial effects of the present invention are: This invention relates to a method for preparing a biomimetic bamboo-like columnar crystal structure thermal barrier coating. By designing and coupling parameters for the EB-PVD preparation process, and utilizing the density of the cloud evaporation by electron beam and the regular perturbation of the cloud by gas, the growth process and microstructure of the columnar crystals are effectively controlled. This results in a thermal barrier coating with a biomimetic bamboo-like columnar crystal structure, increasing the number of scattering layers at the inter-crystal interface, shortening the mean free path of phonon scattering in the microscopic heat conduction process, effectively reducing the thermal conductivity of the thermal barrier coating, improving its thermal insulation capability, and simultaneously ensuring the thermal shock life of the columnar crystals under high strain tolerance. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the coupling effect between the electron beam and the guiding gas flow during the ceramic layer deposition process. The workpiece in the diagram is a sample. Figure 2 The microstructure of the coating cross section in Example 1 is a biomimetic bamboo-like columnar crystal structure; Figure 3 The microstructure of the coating cross section in Example 2 is a biomimetic bamboo-like columnar crystal structure; Figure 4 The microstructure of the coating cross section in Example 3 is a biomimetic bamboo-like columnar crystal structure; Figure 5 The thermal conductivity of the thermal barrier coatings prepared in Comparative Examples 3 and 6 and Examples 1-3 is shown to be that the biomimetic bamboo-like structure can effectively reduce the thermal conductivity of the thermal barrier coating. Figure 6 The thermal shock lifetime of the thermal barrier coatings prepared in Comparative Examples 3, 6 and Examples 1-3 shows that the biomimetic bamboo-like structure has a thermal shock lifetime comparable to that of the ordinary columnar crystal structure. Figure 7 This refers to the periodic control process in Example 1; Figure 8 This refers to the periodic control process in Example 2; Figure 9 This refers to the periodic control process in Example 3; Figure 10 This is the periodic control process in Comparative Example 2; Figure 11 This is the periodic control process in Comparative Example 3; Figure 12 This is a comparison of the periodic control process in Example 5; Figure 13 This is a comparison of the periodic control process in Example 6; Figure 14 This is the periodic control process in Comparative Example 7; Figure 15 For comparison, the periodic control process in Example 8; Figure 16 For comparison, the periodic control process in Example 9; Figure 17 This is the periodic control process in Comparative Example 10; Figure 18 This is the periodic control process in Comparative Example 11; Figure 19 This is the periodic control process in Comparative Example 12; Figure 20 This is the periodic control process in Comparative Example 13; Figure 21 This is the periodic control process in Comparative Example 14. Detailed Implementation

[0017] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. The features of various aspects of the embodiments of the present invention will be described in detail below. In the following detailed description, many specific details are set forth in order to provide a thorough understanding of the present invention.

[0018] To demonstrate the stability and unique performance of the biomimetic bamboo-like columnar crystal structure thermal barrier coating preparation process, multiple sets of experiments were conducted, as shown in Examples 1-3. The regularity of the prepared biomimetic bamboo-like columnar crystal structure thermal barrier coating was observed. Furthermore, to illustrate the special characteristics of the biomimetic bamboo-like columnar crystal structure thermal barrier coating process, multiple sets of comparative analysis experiments were performed. Comparative Examples 1-4 illustrate the effect of the thermal barrier coating deposition sample temperature on the preparation of the biomimetic bamboo-like columnar crystal structure thermal barrier coating; Comparative Examples 5-8 illustrate the effect of vacuum degree on the preparation of the bamboo-like columnar crystal structure thermal barrier coating; and Comparative Examples 9-14 illustrate the effect of target material composition and corresponding deposition level on the preparation of the bamboo-like columnar crystal structure thermal barrier coating.

[0019] In the following description, the sandblasting, cleaning, and dehydration drying processes in the examples and comparative examples all adopted conventional processes. Sandblasting was performed using water blowing, with a blowing pressure of 0.2-0.4 MPa, a blowing time of 5-10 min, and a sand particle size of 100-200 mesh. Cleaning was performed using anhydrous ethanol of analytical grade as the solvent, for a cleaning time of 15-20 min. Drying was carried out at a temperature of 60-90℃ for a drying time of 20-30 min.

[0020] In the examples and comparative examples, the metal bonding layer was prepared on the substrate using vacuum arc plating process parameters: arc current: 500~600A, arc voltage: 20-40V, substrate bias voltage: 10~30V, vacuum degree: <1×10 -2Pa, matrix temperature: 200-400℃.

[0021] Example 1: (1) Sandblasting: The surface of the substrate is treated with contaminants using conventional water sandblasting method; (2) Cleaning: Rinse the sample surface with tap water and immerse the substrate in deionized water; (3) Dehydration and drying: Immerse the matrix in an organic solvent, then remove it and place it in an oven to dry; (4) Obtaining the sample: A metal bonding layer was prepared on the substrate using a conventional vacuum arc plating process. The metal bonding layer was NiCrAlYSi. (5) Preparation of ceramic surface layer: A 20wt% yttrium-stabilized zirconia (20YSZ) target was loaded into the deposition chamber of an electron beam physical vapor deposition (EPV) system. The sample was advanced to a position directly above the YSZ target, with a vertical distance of 300mm. A YSZ thermal barrier coating was obtained on the rotating sample. Deposition process parameters: vacuum degree < 3 × 10⁻⁶ -2 Pa, sample temperature 950℃, select gear 3 according to the yttrium oxide content of the target material (20YSZ) for periodic control of electron beam and guide gas flow, as shown in the flowchart below. The guide gas flow composition ratio is Ar:O2=1:2, the angle between the guide gas flow and the horizontal plane of the crucible is 25°, the horizontal distance from the crucible is 200mm, the vertical distance is 250mm, the guide evaporation time is 60min, after cooling to below 200℃, open the loading chamber to obtain the YSZ ceramic layer.

[0022] Example 2: (1) Sandblasting: The surface of the substrate is treated with contaminants using conventional water sandblasting method; (2) Cleaning: Rinse the sample surface with tap water and immerse the substrate in deionized water; (3) Dehydration and drying: Immerse the matrix in an organic solvent, then remove it and place it in an oven to dry; (4) Obtaining the sample: A metal bonding layer was prepared on the substrate using a conventional vacuum arc plating process. The metal bonding layer was NiCrAlYSi. (5) Preparation of ceramic surface layer: A 13wt% yttrium-stabilized zirconia (13YSZ) target was loaded into the deposition chamber of an electron beam physical vapor deposition (EPV) system. The sample was advanced to directly above the YSZ target at a vertical distance of 300mm. A YSZ thermal barrier coating was obtained on the rotating sample. Deposition process parameters: vacuum degree < 3 × 10⁻⁶ -2Pa, sample temperature 950℃, select gear two according to the yttrium oxide content (13YSZ) of the target material, and control the electron beam and guide gas flow periodically, as shown in the flowchart below. The composition ratio of the guide gas flow is Ar:O2=1:2, the angle between the guide gas flow and the horizontal plane of the crucible is 25°, the horizontal distance from the crucible is 200mm, the vertical distance is 250mm, the guide evaporation time is 60min, after cooling to below 200 degrees Celsius, open the loading chamber to obtain the YSZ ceramic layer.

[0023] Example 3: (1) Sandblasting: The surface of the substrate is treated with contaminants using conventional water sandblasting method; (2) Cleaning: Rinse the sample surface with tap water and immerse the substrate in deionized water; (3) Dehydration and drying: Immerse the matrix in an organic solvent, then remove it and place it in an oven to dry; (4) Obtaining the sample: A metal bonding layer was prepared on the substrate using a conventional vacuum arc plating process. The metal bonding layer was NiCrAlYSi. (5) Preparation of ceramic surface layer: An 8wt% yttrium-stabilized zirconia (8YSZ) target was loaded into the deposition chamber of an electron beam physical vapor deposition (EPV) system. The sample was advanced to a position directly above the YSZ target, with a vertical distance of 300 mm. A YSZ thermal barrier coating was obtained on the rotating sample. Deposition process parameters: vacuum degree < 3 × 10⁻⁶ -2 Pa, sample temperature 950℃, select gear one according to the yttrium oxide content of the target material (8YSZ) for periodic control of electron beam and guide gas flow, as shown in the flowchart below. The guide gas flow composition ratio is Ar:O2=1:2, the angle between the guide gas flow and the horizontal plane of the crucible is 25°, the horizontal distance from the crucible is 200mm, the vertical distance is 250mm, the guide evaporation time is 60min, after cooling to below 200℃, open the loading chamber to obtain the YSZ ceramic layer.

[0024] The effect of deposition temperature on the preparation of bamboo-like columnar crystal structure thermal barrier coatings: Comparative Example 1: (1) Sandblasting: The surface of the substrate is treated with contaminants using conventional water sandblasting method; (2) Cleaning: Rinse the sample surface with tap water and immerse the substrate in deionized water; (3) Dehydration and drying: Immerse the matrix in an organic solvent, then remove it and place it in an oven to dry; (4) Obtaining the sample: A metal bonding layer was prepared on the substrate using a conventional vacuum arc plating process. The metal bonding layer was NiCrAlYSi. (5) Preparation of ceramic surface layer: A 20wt% yttrium-stabilized zirconia (20YSZ) target was loaded into the deposition chamber of an electron beam physical vapor deposition (EPV) system. The sample was advanced to a position directly above the YSZ target, with a vertical distance of 300mm. A YSZ thermal barrier coating was obtained on the rotating sample. Deposition process parameters: vacuum degree < 3 × 10⁻⁶ -2 Pa, sample temperature 750℃, electron beam current intensity constant at 1.5A, no guide gas introduced, evaporation time 60min, after cooling to below 200℃, the loading chamber is opened to obtain the YSZ ceramic layer.

[0025] Comparative Example 2: (1) Sandblasting: The surface of the substrate is treated with contaminants using conventional water sandblasting method; (2) Cleaning: Rinse the sample surface with tap water and immerse the substrate in deionized water; (3) Dehydration and drying: Immerse the matrix in an organic solvent, then remove it and place it in an oven to dry; (4) Obtaining the sample: A metal bonding layer was prepared on the substrate using a conventional vacuum arc plating process. The metal bonding layer was NiCrAlYSi. (5) Preparation of ceramic surface layer: A 20wt% yttrium-stabilized zirconia (20YSZ) target was loaded into the deposition chamber of an electron beam physical vapor deposition (EPV) system. The sample was advanced to a position directly above the YSZ target, with a vertical distance of 300mm. A YSZ thermal barrier coating was obtained on the rotating sample. Deposition process parameters: vacuum degree < 3 × 10⁻⁶ -2 Pa, sample temperature 750℃, select gear 3 according to the yttrium oxide content of the target material (20YSZ) for periodic control of electron beam and guide gas flow, as shown in the flowchart below. The guide gas flow composition ratio is Ar:O2=1:2, the angle between the guide gas flow and the horizontal plane of the crucible is 25°, the horizontal distance from the crucible is 200mm, the vertical distance is 250mm, the guide evaporation time is 60min, after cooling to below 200 degrees Celsius, open the loading chamber to obtain the YSZ ceramic layer.

[0026] Comparative Example 3: (1) Sandblasting: The surface of the substrate is treated with contaminants using conventional water sandblasting method; (2) Cleaning: Rinse the sample surface with tap water and immerse the substrate in deionized water; (3) Dehydration and drying: Immerse the matrix in an organic solvent, then remove it and place it in an oven to dry; (4) Obtaining the sample: A metal bonding layer was prepared on the substrate using a conventional vacuum arc plating process. The metal bonding layer was NiCrAlYSi. (5) Preparation of ceramic surface layer: A 20wt% yttrium-stabilized zirconia (20YSZ) target was loaded into the deposition chamber of an electron beam physical vapor deposition (EPV) system. The sample was advanced to a position directly above the YSZ target, with a vertical distance of 300mm. A YSZ thermal barrier coating was obtained on the rotating sample. Deposition process parameters: vacuum degree < 3 × 10⁻⁶ -2 Pa, sample temperature 950℃, electron beam current intensity constant at 1.5A, no guide gas introduced, evaporation time 60min, after cooling to below 200℃, the loading chamber is opened to obtain the YSZ ceramic layer.

[0027] Comparative Example 4: (1) Sandblasting: The surface of the substrate is treated with contaminants using conventional water sandblasting method; (2) Cleaning: Rinse the sample surface with tap water and immerse the substrate in deionized water; (3) Dehydration and drying: Immerse the matrix in an organic solvent, then remove it and place it in an oven to dry; (4) Obtaining the sample: A metal bonding layer was prepared on the substrate using a conventional vacuum arc plating process. The metal bonding layer was NiCrAlYSi. (5) Preparation of ceramic surface layer: A 20wt% yttrium-stabilized zirconia (20YSZ) target was loaded into the deposition chamber of an electron beam physical vapor deposition (EPV) system. The sample was advanced to a position directly above the YSZ target, with a vertical distance of 300mm. A YSZ thermal barrier coating was obtained on the rotating sample. Deposition process parameters: vacuum degree < 3 × 10⁻⁶ -2 Pa, sample temperature 1150℃, according to the yttrium oxide content of the target material (20YSZ), select gear three for periodic control of electron beam and guide gas flow, as shown in the flowchart below. The guide gas flow composition ratio is Ar:O2=1:2, the angle between the guide gas flow and the horizontal plane of the crucible is 25°, the horizontal distance from the crucible is 200mm, the vertical distance is 250mm, the guide evaporation time is 60min, after cooling to below 200 degrees Celsius, the loading chamber is opened to obtain the YSZ ceramic layer.

[0028] The microstructure of the ceramic layer obtained from the thermal barrier coating preparations of Comparative Examples 1-4 and Example 1 is shown in Table 1. When the deposition temperature of the samples was below 950°C, the ceramic layer could not form a columnar crystal structure. When the deposition temperature was above 1000°C, the ceramic layer grew to form an equiaxed crystal structure. When the samples were in the range of 950-1000°C, the ceramic layer formed a columnar crystal structure. With the use of a periodic cyclic deposition step with guiding gas, a bamboo-like columnar crystal structure was formed.

[0029] Table 1. Microstructure of ceramic layers in Comparative Examples 1-4 and Example 1

[0030] The effect of vacuum degree on the preparation of bamboo-like columnar crystal structure thermal barrier coatings: Comparative Example 5: (1) Sandblasting: The surface of the substrate is treated with contaminants using conventional water sandblasting method; (2) Cleaning: Rinse the sample surface with tap water and immerse the substrate in deionized water; (3) Dehydration and drying: Immerse the matrix in an organic solvent, then remove it and place it in an oven to dry; (4) Obtaining the sample: A metal bonding layer was prepared on the substrate using a conventional vacuum arc plating process. The metal bonding layer was NiCrAlYSi. (5) Preparation of ceramic surface layer: A 20wt% yttrium-stabilized zirconia (20YSZ) target was loaded into the deposition chamber of an electron beam physical vapor deposition (EPV) system. The sample was advanced to directly above the YSZ target at a vertical distance of 300mm. A YSZ thermal barrier coating was obtained on the rotating sample. Deposition process parameters: vacuum degree > 5 × 10⁻⁶ -1 Pa, sample temperature 950℃, select gear 3 according to the yttrium oxide content of the target material (20YSZ) for periodic control of electron beam and guide gas flow, as shown in the flowchart below. The guide gas flow composition ratio is Ar:O2=1:2, the angle between the guide gas flow and the horizontal plane of the crucible is 25°, the horizontal distance from the crucible is 200mm, the vertical distance is 250mm, the guide evaporation time is 60min, after cooling to below 200℃, open the loading chamber to obtain the YSZ ceramic layer.

[0031] Comparative Example 6: (1) Sandblasting: The surface of the substrate is treated with contaminants using conventional water sandblasting method; (2) Cleaning: Rinse the sample surface with tap water and immerse the substrate in deionized water; (3) Dehydration and drying: Immerse the matrix in an organic solvent, then remove it and place it in an oven to dry; (4) Obtaining the sample: A metal bonding layer was prepared on the substrate using a conventional vacuum arc plating process. The metal bonding layer was NiCrAlYSi. (5) Preparation of ceramic surface layer: A 20wt% yttrium-stabilized zirconia (20YSZ) target was loaded into the deposition chamber of an electron beam physical vapor deposition (EPV) system. The sample was advanced to a position directly above the YSZ target, with a vertical distance of 300mm. A YSZ thermal barrier coating was obtained on the rotating sample. Deposition process parameters: vacuum degree 3×10 -2 Pa~5×10 -1Pa, sample temperature 950℃, select gear 3 according to the yttrium oxide content of the target material (20YSZ) for periodic control of electron beam and guide gas flow, as shown in the flowchart below. The guide gas flow composition ratio is Ar:O2=1:2, the angle between the guide gas flow and the horizontal plane of the crucible is 25°, the horizontal distance from the crucible is 200mm, the vertical distance is 250mm, the guide evaporation time is 60min, after cooling to below 200℃, open the loading chamber to obtain the YSZ ceramic layer.

[0032] Comparative Example 7: (1) Sandblasting: The surface of the substrate is treated with contaminants using conventional water sandblasting method; (2) Cleaning: Rinse the sample surface with tap water and immerse the substrate in deionized water; (3) Dehydration and drying: Immerse the matrix in an organic solvent, then remove it and place it in an oven to dry; (4) Obtaining the sample: A metal bonding layer was prepared on the substrate using a conventional vacuum arc plating process. The metal bonding layer was NiCrAlYSi. (5) Preparation of ceramic surface layer: A 13wt% yttrium-stabilized zirconia (13YSZ) target was loaded into the deposition chamber of an electron beam physical vapor deposition (EPV) system. The sample was advanced to directly above the YSZ target at a vertical distance of 300mm. A YSZ thermal barrier coating was obtained on the rotating sample. Deposition process parameters: vacuum degree 3×10 -2 Pa~5×10 -1 Pa, sample temperature 950℃, select gear two according to the yttrium oxide content (13YSZ) of the target material, and control the electron beam and guide gas flow periodically, as shown in the flowchart below. The composition ratio of the guide gas flow is Ar:O2=1:2, the angle between the guide gas flow and the horizontal plane of the crucible is 25°, the horizontal distance from the crucible is 200mm, the vertical distance is 250mm, the guide evaporation time is 60min, after cooling to below 200 degrees Celsius, open the loading chamber to obtain the YSZ ceramic layer.

[0033] Comparative Example 8: (1) Sandblasting: The surface of the substrate is treated with contaminants using conventional water sandblasting method; (2) Cleaning: Rinse the sample surface with tap water and immerse the substrate in deionized water; (3) Dehydration and drying: Immerse the matrix in an organic solvent, then remove it and place it in an oven to dry; (4) Obtaining the sample: A metal bonding layer was prepared on the substrate using a conventional vacuum arc plating process. The metal bonding layer was NiCrAlYSi. (5) Ceramic surface layer preparation: An 8wt% yttrium-stabilized zirconia (8YSZ) target was loaded into the deposition chamber of an electron beam physical vapor deposition (EPV) system. The sample was advanced to a position directly above the YSZ target, with a vertical distance of 300 mm. A YSZ thermal barrier coating was obtained on the rotating sample. Deposition process parameters: vacuum degree 3×10 -2 Pa~5×10 -1 Pa a, sample temperature 950℃, according to the yttrium oxide content of the target material (8YSZ), select gear two for periodic control of electron beam and guide gas flow, as shown in the flowchart below. The guide gas flow composition ratio is Ar:O2=1:2, the angle between the guide gas flow and the horizontal plane of the crucible is 25°, the horizontal distance from the crucible is 200mm, the vertical distance is 250mm, the guide evaporation time is 60min, after cooling to below 200 degrees Celsius, the loading chamber is opened to obtain the YSZ ceramic layer.

[0034] The effect of vacuum degree on tissue growth is illustrated by comparing Comparative Examples 5-8 and Examples 1-3, since vacuum degree > 5 × 10⁻⁶. -3 At a pressure of Pa, the electron beam of the equipment could not operate stably, resulting in the failure of preparation in Comparative Example 5, and the ceramic surface layer could not be obtained. The microstructures prepared in Comparative Examples 5-8 and Examples 1-3 are shown in Table 2. Meanwhile, at a vacuum degree of 3 × 10⁻⁶ Pa, the electron beam of the equipment could not operate stably, leading to the failure of preparation in Comparative Example 5, and the ceramic surface layer could not be obtained. -4 ~5×10 -3 At a vacuum level of Pa, the coating microstructure prepared by the process is a columnar crystalline structure, without any bamboo-like formation. This may be because, at a lower vacuum level, the guiding gas cannot effectively disturb the vapor clouds during the coating deposition process, thus affecting the resulting microstructure. In Examples 1-3, the vacuum level was <3×10⁻⁶. -4 Pa, guiding the gas can form an effective disturbance, thus obtaining a bamboo-like columnar crystal structure.

[0035] Table 2. Growth tissue structures of Comparative Examples 5-8 and Examples 1-3

[0036] The effect of target material composition on the preparation of bamboo-like columnar crystalline thermal barrier coatings: Comparative Example 9: (1) Sandblasting: The surface of the substrate is treated with contaminants using conventional water sandblasting method; (2) Cleaning: Rinse the sample surface with tap water and immerse the substrate in deionized water; (3) Dehydration and drying: Immerse the matrix in an organic solvent, then remove it and place it in an oven to dry; (4) Obtaining the sample: A metal bonding layer was prepared on the substrate using a conventional vacuum arc plating process. The metal bonding layer was NiCrAlYSi. (5) Preparation of ceramic surface layer: A 20wt% yttrium-stabilized zirconia (20YSZ) target was loaded into the deposition chamber of an electron beam physical vapor deposition (EPV) system. The sample was advanced to a position directly above the YSZ target, with a vertical distance of 300mm. A YSZ thermal barrier coating was obtained on the rotating sample. Deposition process parameters: vacuum degree < 3 × 10⁻⁶ -2 Pa, sample temperature 950℃, select setting 1 for periodic control of electron beam and guide gas flow, as shown in the flowchart below. The guide gas flow composition ratio is Ar:O2=1:2, the angle between the guide gas flow and the horizontal plane of the crucible is 25°, the horizontal distance from the crucible is 200mm, the vertical distance is 250mm, the guide evaporation time is 60min, after cooling to below 200℃, the loading chamber is opened to obtain the YSZ ceramic layer.

[0037] Comparative Example 10: (1) Sandblasting: The surface of the substrate is treated with contaminants using conventional water sandblasting method; (2) Cleaning: Rinse the sample surface with tap water and immerse the substrate in deionized water; (3) Dehydration and drying: Immerse the matrix in an organic solvent, then remove it and place it in an oven to dry; (4) Obtaining the sample: A metal bonding layer was prepared on the substrate using a conventional vacuum arc plating process. The metal bonding layer was NiCrAlYSi. (5) Preparation of ceramic surface layer: A 20wt% yttrium-stabilized zirconia (20YSZ) target was loaded into the deposition chamber of an electron beam physical vapor deposition (EPV) system. The sample was advanced to a position directly above the YSZ target, with a vertical distance of 300mm. A YSZ thermal barrier coating was obtained on the rotating sample. Deposition process parameters: vacuum degree < 3 × 10⁻⁶ -2 Pa, sample temperature 950℃, select setting 2 for periodic control of electron beam and guide gas flow, as shown in the flowchart below. The guide gas flow composition ratio is Ar:O2=1:2, the angle between the guide gas flow and the horizontal plane of the crucible is 25°, the horizontal distance from the crucible is 200mm, the vertical distance is 250mm, the guide evaporation time is 60min, after cooling to below 200℃, the loading chamber is opened to obtain the YSZ ceramic layer.

[0038] Comparative Example 11: (1) Sandblasting: The surface of the substrate is treated with contaminants using conventional water sandblasting method; (2) Cleaning: Rinse the sample surface with tap water and immerse the substrate in deionized water; (3) Dehydration and drying: Immerse the matrix in an organic solvent, then remove it and place it in an oven to dry; (4) Obtaining the sample: A metal bonding layer was prepared on the substrate using a conventional vacuum arc plating process. The metal bonding layer was NiCrAlYSi. (5) Preparation of ceramic surface layer: A 13wt% yttrium-stabilized zirconia (13YSZ) target was loaded into the deposition chamber of an electron beam physical vapor deposition (EPV) system. The sample was advanced to directly above the YSZ target at a vertical distance of 300mm. A YSZ thermal barrier coating was obtained on the rotating sample. Deposition process parameters: vacuum degree < 3 × 10⁻⁶ -2 Pa, sample temperature 950℃, select setting 1 for periodic control of electron beam and guide gas flow, as shown in the flowchart below. The guide gas flow composition ratio is Ar:O2=1:2, the angle between the guide gas flow and the horizontal plane of the crucible is 25°, the horizontal distance from the crucible is 200mm, the vertical distance is 250mm, the guide evaporation time is 60min, after cooling to below 200℃, the loading chamber is opened to obtain the YSZ ceramic layer.

[0039] Comparative Example 12: (1) Sandblasting: The surface of the substrate is treated with contaminants using conventional water sandblasting method; (2) Cleaning: Rinse the sample surface with tap water and immerse the substrate in deionized water; (3) Dehydration and drying: Immerse the matrix in an organic solvent, then remove it and place it in an oven to dry; (4) Obtaining the sample: A metal bonding layer was prepared on the substrate using a conventional vacuum arc plating process. The metal bonding layer was NiCrAlYSi. (5) Preparation of ceramic surface layer: A 13wt% yttrium-stabilized zirconia (13YSZ) target was loaded into the deposition chamber of an electron beam physical vapor deposition (EPV) system. The sample was advanced to directly above the YSZ target at a vertical distance of 300mm. A YSZ thermal barrier coating was obtained on the rotating sample. Deposition process parameters: vacuum degree < 3 × 10⁻⁶ -2 Pa, sample temperature 950℃, select gear 3 for periodic control of electron beam and guide gas flow, as shown in the flowchart below. The guide gas flow composition ratio is Ar:O2=1:2, the angle between the guide gas flow and the horizontal plane of the crucible is 25°, the horizontal distance from the crucible is 200mm, the vertical distance is 250mm, the guide evaporation time is 60min, after cooling to below 200℃, the loading chamber is opened to obtain the YSZ ceramic layer.

[0040] Comparative Example 13: (1) Sandblasting: The surface of the substrate is treated with contaminants using conventional water sandblasting method; (2) Cleaning: Rinse the sample surface with tap water and immerse the substrate in deionized water; (3) Dehydration and drying: Immerse the matrix in an organic solvent, then remove it and place it in an oven to dry; (4) Obtaining the sample: A metal bonding layer was prepared on the substrate using a conventional vacuum arc plating process. The metal bonding layer was NiCrAlYSi. (5) Preparation of ceramic surface layer: An 8wt% yttrium-stabilized zirconia (8YSZ) target was loaded into the deposition chamber of an electron beam physical vapor deposition (EPV) system. The sample was advanced to a position directly above the YSZ target, with a vertical distance of 300 mm. A YSZ thermal barrier coating was obtained on the rotating sample. Deposition process parameters: vacuum degree < 3 × 10⁻⁶ -2 Pa, sample temperature 950℃, select gear two according to the yttrium oxide content of the target material (8YSZ) for periodic control of electron beam and guide gas flow, as shown in the flowchart below. The guide gas flow composition ratio is Ar:O2=1:2, the angle between the guide gas flow and the horizontal plane of the crucible is 25°, the horizontal distance from the crucible is 200mm, the vertical distance is 250mm, the guide evaporation time is 60min, after cooling to below 200℃, open the loading chamber to obtain the YSZ ceramic layer.

[0041] Comparative Example 14: (1) Sandblasting: The surface of the substrate is treated with contaminants using conventional water sandblasting method; (2) Cleaning: Rinse the sample surface with tap water and immerse the substrate in deionized water; (3) Dehydration and drying: Immerse the matrix in an organic solvent, then remove it and place it in an oven to dry; (4) Obtaining the sample: A metal bonding layer was prepared on the substrate using a conventional vacuum arc plating process. The metal bonding layer was NiCrAlYSi. (5) Preparation of ceramic surface layer: An 8wt% yttrium-stabilized zirconia (8YSZ) target was loaded into the deposition chamber of an electron beam physical vapor deposition (EPV) system. The sample was advanced to a position directly above the YSZ target, with a vertical distance of 300 mm. A YSZ thermal barrier coating was obtained on the rotating sample. Deposition process parameters: vacuum degree < 3 × 10⁻⁶ -2 Pa, sample temperature 950℃, select gear 3 according to the yttrium oxide content of the target material (8YSZ) for periodic control of electron beam and guide gas flow, as shown in the flowchart below. The guide gas flow composition ratio is Ar:O2=1:2, the angle between the guide gas flow and the horizontal plane of the crucible is 25°, the horizontal distance from the crucible is 200mm, the vertical distance is 250mm, the guide evaporation time is 60min, after cooling to below 200℃, open the loading chamber to obtain the YSZ ceramic layer.

[0042] Comparative Examples 9-14 illustrate the deposition of coatings with different yttrium oxide contents in the target material when using non-corresponding gear settings. The yttrium oxide contents of the coatings in Comparative Examples 9-14 and Examples 1-3 after deposition are shown in Table X. The yttrium oxide contents of the coatings in Examples 1-3 show good consistency with the target material, with weak compositional shift. In Comparative Examples 9-14, after deposition with different target material compositions using non-corresponding gear settings, the yttrium oxide content of the coatings varies significantly relative to the target material, resulting in a noticeable shift in coating composition. Due to the difference in saturated vapor pressure between yttrium oxide and zirconium oxide, the guide gas flow rate and electron beam intensity corresponding to different target material compositions are quite sensitive, leading to compositional shift in the coating. Therefore, a correspondence between the target material composition and the gear setting selection is necessary to obtain a bamboo-like columnar crystalline thermal barrier coating with good compositional uniformity.

[0043] Table 3. Yttrium oxide content of coatings in Comparative Examples 9-14 and Examples 1-3

[0044] The samples prepared according to the above comparative examples and embodiments were analyzed, and their cross-sectional microstructure morphology was observed. Examples 1-3 showed a distinct columnar crystal structure. Through periodic control of the guiding gas flow and electron beam current corresponding to different compositions, a distinct biomimetic bamboo-like structure was obtained. With changes in target material composition and process parameters, the size and shape of the bamboo-like structure changed. In Example 1, the electron beam current was higher, resulting in a larger cloud density during crystal growth and a more obvious growth structure. However, due to the corresponding larger guiding gas flow, the disturbance to the columnar crystal growth was more significant, resulting in thinner and longer bamboo-like segments with more distinct connecting nodes. Figure 2 As shown; in Example 2, both the electron beam current and the guiding gas flow are reduced, the disturbance to the growth of columnar crystals is reduced, the bamboo-like main trunk is more obvious, and the connecting nodes are shortened, exhibiting a thick main trunk and shorter connecting nodes, as shown. Figure 3 As shown; in Example 3, the electron beam current and guiding gas flow are minimized, resulting in the least impact on columnar crystal growth. Therefore, it exhibits a bamboo-like columnar crystal structure similar to a porous, layered structure, such as... Figure 4 As shown. The effects of deposition temperature, deposition vacuum, and target material composition on the preparation process of bamboo-like columnar crystals were compared. The thermal conductivity of the tested examples and related comparative examples was also examined. Figure 5 As shown, it can be found that the thermal barrier coating with a bamboo-like columnar crystal structure has a thermal conductivity that is about 20% lower than that of a common columnar crystal structure, and has a thermal shock life that is comparable to that of a common columnar crystal structure. Figure 6 It exhibits excellent performance.

[0045] In summary, as can be seen from the above embodiments, the technical solution of the present invention has the following advantages compared with the prior art: (1) In terms of coating preparation, by designing the changes in the preparation process parameters of the sample, the growth rate and size of columnar crystals on the sample surface are dynamically changed, and a thermal barrier coating with multi-level ordered porous microstructure columnar crystal arrangement is obtained.

[0046] (2) In terms of coating performance, the multi-level ordered microstructure can increase the pore structure of the thermal barrier coating, shorten the mean free path of phonon scattering in the micro-conduction process, effectively reduce the thermal conductivity of the thermal barrier coating, and improve the thermal insulation capacity.

Claims

1. A method for preparing a biomimetic bamboo-like columnar crystal structure thermal barrier coating, characterized in that: Includes the following steps: Step 1: Sandblast and clean the substrate surface; Step 2: Prepare a metal bonding layer on the substrate surface to obtain a sample. The preparation process can be one of plasma spraying, vacuum arc plating, or magnetron sputtering. Step 3: In the preparation of the ceramic surface layer, electron beam physical vapor deposition (EBPD) is used. A ceramic target for surface layer evaporation is selected, and the deposition temperature is controlled within a specific range to ensure stable growth of the ordered columnar crystal structure. The initial vacuum level is controlled at a high level to increase the perturbation effect of the guiding gas on the vapor cloud and columnar crystal growth. During deposition, a guiding gas flow is added to directly influence the vapor cloud flow. By periodically adjusting the electron beam current and guiding gas flow rate, a bamboo-like columnar crystal structure is constructed. The deposition time is 60-100 minutes. The periodic control process of the guiding gas flow rate and electron beam current is as follows: The first process involves 120-200 seconds of normal coating deposition without guiding gas flow, with an electron beam current of 1.4A-1.6A; the second process involves 20-30 seconds of gas flow rate and electron beam coupling control. This deposition process is repeated until the coating deposition is complete. In the second process, the gas flow rate and electron beam coupling control parameters are divided into three levels: First setting: Guide gas flow rate 55-65 sccm, electron beam current 1.18-1.22 A; Second setting: Guide gas flow rate 75-85 sccm, electron beam current 1.23-1.27 A; Third setting: Guide gas flow rate 95-105 sccm, electron beam current 1.33-1.37A.

2. The preparation method according to claim 1, characterized in that: The ceramic surface evaporation target in step three is a 7-20 wt% yttrium-stabilized zirconia (7-20 YSZ) ceramic target.

3. The preparation method according to claim 1, characterized in that: The deposition temperature for the three steps is 850℃~1000℃.

4. The preparation method according to claim 1, characterized in that: The initial vacuum level of the deposition chamber in step three is <3×10⁻⁶. -2 Pa.

5. The preparation method according to claim 2, characterized in that: Different parameter levels are selected based on the composition of the ceramic surface target material: When 16% < yttrium oxide content ≤ 20 wt%, select the third parameter level; When the yttrium oxide content is 11-16 wt%, the second parameter should be selected; When the yttrium oxide content is between 7% and 11 wt%, the first parameter should be selected.

6. The preparation method according to claim 1, characterized in that: The matrix composition is a nickel-based single-crystal high-temperature alloy.

7. The preparation method according to claim 1, characterized in that: The metal bonding layer is composed of one of NiPtAl, NiCoCrAlY, NiCrAlYSi, and NiCoCrAlYHf.

8. The preparation method according to claim 1, characterized in that: The guiding gas in step three is a mixture of Ar and O2, with a flow rate ratio of 1:

2.

9. The preparation method according to claim 1, characterized in that: In step three, the angle between the guiding airflow and the horizontal plane of the crucible is 25±3°, and the horizontal distance between the guiding airflow and the crucible is 200±20mm, and the vertical distance is 250±20mm.

10. The preparation method according to claim 1, characterized in that: In step three, the sample is placed directly above the crucible, with a vertical distance of 300±20mm from the crucible.

11. The preparation method according to claim 1, characterized in that: The plasma spraying process parameters in step two are as follows: spraying power: 20-60kW, spraying distance: 80-120mm, carrier gas composition: high-purity Ar or high-purity N2, carrier gas flow rate: 3-8L / min, powder feeding rate: 20-40g / min, substrate preheating temperature: 150-300℃.

12. The preparation method according to claim 1, characterized in that: The vacuum arc plating process parameters in step two are as follows: arc current: 500-600A, arc voltage: 20-40V, substrate bias voltage: 10-30V, vacuum degree: <1×10⁻⁶ -2 Pa, matrix temperature: 200-400℃.

13. The preparation method according to claim 1, characterized in that: The magnetron sputtering process parameters in step two are: 5-10 W / cm² 2 Working air pressure: 0.3-0.8Pa, substrate bias voltage: 80-100V, target-substrate distance: 80-100mm, substrate temperature: 200-350℃.

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