A method for monitoring the thickness of an electron beam physical vapor deposition thermal barrier coating

Abstract

The application discloses a kind of electron beam physical vapor deposition thermal barrier coating thickness monitoring method, it is related to thermal barrier coating preparation technical field, comprising the following steps: monitoring device is arranged in vacuum cavity, target material of selecting suitable material;Thermal barrier coating is prepared by electron beam physical vapor deposition process, obtains a variety of parameters in process;The thickness of thermal barrier coating is calculated by computer using self-defined function formula;After obtaining calculated value, process is stopped, the actual thickness of sample is measured, and compared with calculated value.Analysis is compared with prior art, can be in the process of electron beam physical vapor deposition process of high vacuum, high temperature by obtaining target material consumption mass, combined with a variety of parameters, the thickness of thermal barrier coating in process is calculated, the stability of process and coating quality is improved, while avoiding multiple rework and defective product situation, reduce process cost, with good practical application prospect.

Description

Technical Field

[0001] This invention relates to the field of thermal barrier coating preparation technology, specifically a method for monitoring the thickness of electron beam physical vapor deposition thermal barrier coatings. Background Technology

[0002] Thermal barrier coatings are a recognized technology that effectively reduces material surface temperature, improves thermal shock resistance, and extends service life, and are widely used in important fields such as aerospace and new energy. Electron beam physical vapor deposition (EBPV) and thermal spraying are currently the only two processes capable of mass-producing qualified thermal barrier coatings. Compared to thermal spraying, EBPV-prepared thermal barrier coatings exhibit a columnar crystalline morphology, providing better strain tolerance and thermal shock resistance. This makes the coating less prone to cracking or peeling even under repeated high-temperature-low-temperature service environments. Therefore, EBPV is currently the only feasible technology for preparing thermal barrier coatings for core components of aero-engines that withstand high temperatures and pressures.

[0003] Thermal barrier coatings prepared by electron beam physical vapor deposition are currently mainly used in high-speed moving parts such as turbine blades and guide vanes. These parts have extremely high requirements for aerodynamics and motion balance. The slight weight changes caused by different thicknesses directly determine whether the coating process is qualified. Moreover, the thickness of the thermal barrier coating is a key indicator affecting the thermal insulation performance. Therefore, the thickness of the thermal barrier coating needs to be designed according to the different requirements of thermal insulation effect, thermal shock resistance and motion balance in different application scenarios. It is also required that the actual thickness prepared is consistent with the theoretical thickness. This requires the preparation process to have the ability to precisely control the coating deposition thickness.

[0004] Currently, the commonly used method for monitoring coating thickness in a vacuum environment is crystal oscillator thickness measurement. Its working principle is to monitor the film thickness through the piezoelectric effect and mass loading effect of quartz crystal. The film thickness monitoring range is 0.1 to 2 μm, and the working temperature does not exceed 150℃. However, in order to ensure a certain thermal protection effect, the thickness of thermal barrier coatings is generally 70 to 300 μm. In order for the target gas to effectively form columnar crystalline coatings on the surface of the workpiece, the workpiece usually needs to be heated, and the heating temperature is generally 700 to 1200℃. This makes it impossible to use the existing vacuum film thickness monitoring method to monitor the thickness of thermal barrier coatings in electron beam physical vapor deposition process.

[0005] The thickness of thermal barrier coatings is affected by many factors, such as the type of target material, target material consumption, workpiece curvature, electron beam power, and deposition temperature. Coupled with the high vacuum and high temperature process environment of electron beam physical vapor deposition, its thickness is difficult to control precisely. Therefore, there is no technology that can accurately monitor the thickness of thermal barrier coatings during the process. Existing thickness assessments of thermal barrier coatings are all performed after the preparation process is completed, using destructive or non-destructive methods or predictions based on a single variable such as process time. These methods are time-delayed, and relying solely on a single variable such as process time can easily lead to substandard or excessive thickness, resulting in workpiece rework or scrap, and indirectly increasing process costs.

[0006] Based on this, a method for monitoring the thickness of electron beam physical vapor deposition thermal barrier coatings is provided, which can eliminate the drawbacks of existing technical solutions. Summary of the Invention

[0007] The purpose of this invention is to provide a method for monitoring the thickness of thermal barrier coatings in electron beam physical vapor deposition (EBPD) to solve the problem in the prior art that the thickness of thermal barrier coatings cannot be monitored in the EBPD process environment, thus making it impossible to accurately control the coating thickness and easily leading to workpiece thickness exceeding or failing to meet the standard, resulting in multiple reworks and increased process costs.

[0008] To achieve the above objectives, the present invention provides the following technical solution:

[0009] A method for monitoring the thickness of an electron beam physical vapor deposition thermal barrier coating includes the following steps:

[0010] S1. Arrange the monitoring device inside the vacuum chamber and select the target material required for the deposition process;

[0011] S2. Prepare thermal barrier coatings using electron beam physical vapor deposition process and obtain various parameters during the process;

[0012] S3. Set up a linear regression model using a computer, and calculate the thickness of the thermal barrier coating using a custom function formula and the above parameters;

[0013] S4. After obtaining the calculated value, stop the process, measure the actual thickness of the sample, and compare and analyze it with the calculated value.

[0014] The method for monitoring the thickness of an electron beam physical vapor deposition thermal barrier coating using steps S1 to S4 described above also specifically involves a thickness monitoring device for the electron beam physical vapor deposition thermal barrier coating, including a vacuum chamber and a computer. The vacuum chamber contains a crucible for placing the target material required for the deposition process. The crucible is a copper water-cooled crucible. A weighing sensor is located at the lower end of the crucible and is connected to the computer via a data cable. A heating device is located at the top of the vacuum chamber, and a workpiece rotating device is installed below the heating device. A workpiece clamping device is connected to one side of the workpiece rotating device. A vacuum device is located at the bottom of the vacuum chamber, and an electron beam emitting device is located above the vacuum device.

[0015] Furthermore, the target material is a yttrium oxide-stabilized zirconium oxide ceramic target or a thermal barrier coating target of other component systems.

[0016] Furthermore, the electron beam emitting device is configured as a direct-fire electron gun or a deflection electron gun with a deflection angle of 0-270°, and the power range of the electron gun is 5-60KW.

[0017] Furthermore, the target material needs to be preheated before the process preparation operation in step S2, and the preheating treatment uses a low-power electron beam.

[0018] Furthermore, in step S3, the computer calculates the thickness of the thermal barrier coating using a custom function formula, specifically including the following steps:

[0019] S31. Define a custom function f(x), where the variable x is the comprehensive calculated value of the electron beam process parameters, i.e., power * time;

[0020] S32. Establish a linear regression model using the INTERCEPT function. The model formula is y = INTERCEPT + B1*x + B2*x^2. 2 +B3*x^ 3 B1, B2, and B3 are all fitting coefficients;

[0021] S33. By comparing the physicochemical properties of the actual target material with those of the standard target material, the physicochemical properties including but not limited to chemical composition, target material density, size, and porosity, the target material coefficient a is determined based on the above values.

[0022] S34. Determine the power coefficient b based on the power value in the electron beam process parameters;

[0023] S35. Calculate the function f(x) = y*a*b;

[0024] S36. Determine the deposition coefficient c based on the workpiece type and deposition temperature value;

[0025] S37. Obtain the mass z of the target material consumed by the weighing sensor, and transmit the above data to the computer via a data cable;

[0026] S38. Calculate h = [z / f(x)] * c to obtain the calculated coating thickness.

[0027] Furthermore, the time in step S31 is obtained through a timer, and the unit of time is minutes.

[0028] Furthermore, the fitting coefficients in step S32 are set to B1≥B2≥B3.

[0029] Furthermore, the numerical range of the target coefficient a in step S33 is 0.80≤a≤1.2.

[0030] Furthermore, the power coefficient b in step S34 has a value range of 0.7 ≤ b ≤ 1.2.

[0031] Furthermore, the deposition coefficient c in step S36 has a value range of 0.7 ≤ c ≤ 1.8.

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

[0033] This invention discloses a method for monitoring the thickness of thermal barrier coatings in electron beam physical vapor deposition (EBPD). Compared with existing technologies, this method utilizes a self-designed weighing device to acquire the mass of the target material consumed during the high-vacuum, high-temperature EBPD process. Combined with electron beam process parameters, target physicochemical coefficients, and workpiece deposition coefficients, the thickness of the thermal barrier coating is calculated using a user-defined function. This facilitates monitoring coating thickness variations during the process, enabling precise adjustment of the coating thickness. It significantly improves the stability of the process and coating quality, while avoiding multiple reworks and defective products. This method substantially reduces the process cost and rejection rate of EBPD for thermal barrier coating preparation, effectively improving process stability and coating quality, and has promising practical application prospects. Attached Figure Description

[0034] Figure 1 This is a schematic diagram of the thickness monitoring device of the present invention;

[0035] Figure 2 This is a schematic diagram comparing the calculated thickness with the actual thickness of the workpiece in an embodiment of the present invention.

[0036] Figure reference numerals: 1. Vacuum chamber; 2. Heating device; 3. Workpiece clamping device; 4. Workpiece rotating device; 5. Workpiece; 6. Target material; 7. Crucible; 8. Weighing sensor; 9. Data cable; 10. Electron beam emitting device; 11. Computer; 12. Vacuum device. Detailed Implementation

[0037] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0038] In this embodiment, as Figures 1-2 As shown, a method for monitoring the thickness of an electron beam physical vapor deposition thermal barrier coating includes the following steps:

[0039] S1. Place the monitoring device inside the vacuum chamber 1 and select the target material 6 required for the deposition process.

[0040] S2. Prepare thermal barrier coatings using electron beam physical vapor deposition process and obtain various parameters during the process;

[0041] S3. Set up a linear regression model using computer 11, and calculate the thickness of the thermal barrier coating using a custom function formula and the above parameters;

[0042] S4. After obtaining the calculated value, stop the process, measure the actual thickness of the sample, and compare and analyze it with the calculated value.

[0043] Specifically, before performing coating deposition on workpiece 5, the electron beam emitting device 10 is cleaned to ensure that it is not prone to frequent high-voltage discharge or interruption, thus increasing its stability. The target material 6 in step S1 is a yttrium oxide-stabilized zirconia ceramic target or a thermal barrier coating target of other component systems. Before placing the target material 6 into the crucible 7, the target material 6 is inspected to ensure its performance stability. The monitoring device (not shown in the figure) is a common component in the field and is existing technology. Through step S4, the thickness monitoring method can be observed and judged based on the comparison results to determine whether it has reference value and accuracy, effectively improving the reliability of the thickness monitoring method and facilitating subsequent analysis operations.

[0044] The method for monitoring the thickness of an electron beam physical vapor deposition thermal barrier coating using steps S1 to S4 also specifically involves a thickness monitoring device for the electron beam physical vapor deposition thermal barrier coating. The principle is to use a high-energy-density electron beam to heat the material to be evaporated (target material 6) in a crucible 7 under high vacuum conditions, causing it to reach a molten and vaporized state. The vaporized material then condenses on the surface of the workpiece 5 to form a coating. The thickness of the coating is monitored. The device includes a vacuum chamber 1 and a computer 11. The vacuum chamber 1 contains a crucible 7 for holding the target material 6 required for the deposition process. The crucible 7 is a copper water-cooled crucible, mainly used in the electron gun industry. It typically consists of side walls and a bottom wall, and has a dual or multi-channel circulating water structure for effective heat dissipation, enhancing the overall strength and stability of the crucible 7. A weighing sensor 8 is located at the lower end of the crucible 7. The weighing sensor 8 obtains the initial mass of the target material 6 and the mass z consumed during the process. 8 is connected to computer 11 via data cable 9. Data cable 9 is a metal-armored high-temperature resistant data cable with an added metal protection layer on the outside of the product to prevent internal damage during transportation and installation, thus protecting the internal cables. Data cable 9 isolates vacuum chamber 1 from the outside world through CF flange metal seal, thus providing a sealing function. A heating device 2 is provided at the top of vacuum chamber 1, with a heating temperature of 700-1200℃, so that the target material 6 can reach a molten and vaporized state, and then evaporate to the surface of workpiece 5 to condense into a coating. A workpiece rotating device 4 is installed below the heating device 2 to facilitate the rotation of workpiece 5. A workpiece clamping device 3 is connected to one side of the workpiece rotating device 4 to hold workpiece 5, which facilitates the fixation of workpiece 5. A vacuum device 12 is provided at the bottom of vacuum chamber 1 to generate, measure and control the vacuum environment. An electron beam emitting device 10 is provided above the vacuum device 12. The electron beam emitting device 10 includes an evaporating electron gun and a preheating electron gun, which preheats the target material 6.

[0045] Among them, such as Figure 1 As shown, the electron beam emitting device 10 is a direct-fire electron gun with a power range of 5 to 60 kW. The electron beam emitting device 10 can also be a deflection electron gun with a deflection angle of 0 to 270° and a power range of 5 to 60 kW, thereby increasing the stability of the coating quality.

[0046] Among them, such as Figure 1 As shown, the target material 6 needs to be preheated before the process preparation operation in step S2. The preheating treatment uses a low-power electron beam, which is convenient for removing impurities or moisture from the surface of the target material 6 and can improve the temperature uniformity of the target material 6, reduce the thermal stress caused by the temperature gradient, and thus reduce the risk of cracking.

[0047] Among them, such as Figure 1 and Figure 2As shown, in step S3, computer 11 calculates the thickness of the thermal barrier coating using a custom function formula, specifically including the following steps:

[0048] S31. Define a custom function f(x), where the variable x is the comprehensive calculated value of the electron beam process parameters, i.e., power * time. The time is obtained through a timer, and the unit of time is minutes.

[0049] S32. Establish a linear regression model using the INTERCEPT function. The model formula is y = INTERCEPT + B1*x + B2*x^2. 2 +B3*x^ 3 B1, B2, and B3 are all fitting coefficients, and the fitting coefficients are set to B1≥B2≥B3;

[0050] S33. By comparing the physicochemical properties of the actual target material 6 with those of the standard target material, including but not limited to chemical composition, target material density, size, and porosity, the target material coefficient a is determined based on the above values. The value range of the target material coefficient a is 0.80≤a≤1.2.

[0051] Specifically, in this embodiment, an 8wt% yttrium-stabilized zirconium oxide target is selected as the thermal barrier coating target, and the quantity is set to 10. The target size is as follows. The target material density is 3.9 g / cm³. 3 The target material porosity is 5-8%. By comparing the above data with the physicochemical properties of the standard target material, the target material coefficient a = 0.90 is determined, which is within the numerical range.

[0052] S34. Based on the power values ​​in the electron beam process parameters, determine the power coefficient b. The range of the power coefficient b is 0.7 ≤ b ≤ 1.2.

[0053] Specifically, in this embodiment, the electron beam power is selected as 40KW, and the power coefficient b is determined to be 1.0, which is within the numerical range;

[0054] S35. Calculate the function f(x) = y*a*b;

[0055] S36. Determine the deposition coefficient c based on the workpiece type and deposition temperature value. The value range of the deposition coefficient c is 0.7≤c≤1.8.

[0056] Specifically, in this embodiment, a flat sample with dimensions of 25x40x3mm and material of GH3030 was selected. The substrate temperature was 700-750℃, and the deposition coefficient was determined to be c = 0.97, which is within the numerical range.

[0057] S37. Obtain the mass z consumed by the target material through the weighing sensor 8, and transmit the above data to the computer 11 through the data cable 9;

[0058] S38. Calculate h = [z / f(x)] * c to obtain the calculated coating thickness;

[0059] Specifically, the calculated coating thickness is obtained by following the above steps. After obtaining the calculated value, the process is stopped, and the sample is taken out. The coating thickness is measured using a cutting machine, metallographic mounting machine, and microscope to obtain the actual thickness of workpiece 5. The thickness comparison results are shown in Table 1. The data shows that the absolute value of the thickness error between the calculated coating thickness and the actual thickness of workpiece 5 is between 0.07 and 2.00 μm. The numerical range is small, which effectively improves the reliability of the thickness monitoring method, facilitates the monitoring of coating thickness changes during the process, achieves the effect of accurately adjusting the coating thickness, effectively improves process stability and coating quality, and has good practical application prospects.

[0060] Table 1

[0061] frequency Example: Calculating Thickness Actual thickness of workpiece Absolute value of thickness error 1 43.58408 44.1 0.51592 2 97.17603 97.1 0.07603 3 104.58738 104.3 0.28738 4 106.01161 105.4 0.61161 5 106.66396 105.9 0.76396 6 112.6374 114.6 1.9626 7 115.39856 116.3 0.90144 8 117.03772 116.6 0.43772 9 117.03772 117.5 0.46228 10 121.11548 120.9 0.21548

[0062] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A method for monitoring the thickness of an electron beam physical vapor deposition thermal barrier coating, characterized in that, Includes the following steps: S1. Place the monitoring device inside the vacuum chamber (1) and select the target material (6) required for the deposition process. S2. Prepare thermal barrier coatings using electron beam physical vapor deposition process and obtain various parameters during the process; S3. Set up a linear regression model using a computer (11) and calculate the thickness of the thermal barrier coating using a custom function formula and the above parameters; S4. After obtaining the calculated value, stop the process, measure the actual thickness of the sample, and compare and analyze it with the calculated value. The use of the electron beam physical vapor deposition thermal barrier coating thickness monitoring method using the above steps S1~S4 also specifically involves an electron beam physical vapor deposition thermal barrier coating thickness monitoring device, including a vacuum chamber (1) and a computer (11). The vacuum chamber (1) is provided with a crucible (7) for placing the target material (6) required for the deposition process. The crucible (7) is a copper water-cooled crucible. A weighing sensor (8) is provided at the lower end of the crucible (7). The weighing sensor (8) is connected to the computer (11) through a data cable (9). A heating device (2) is provided at the top of the vacuum chamber (1). A workpiece rotating device (4) is installed below the heating device (2). A workpiece clamping device (3) for clamping the workpiece (5) is connected to one side of the workpiece rotating device (4). A vacuum device (12) is provided at the bottom of the vacuum chamber (1). An electron beam emitting device (10) is provided above the vacuum device (12). In step S3, the computer (11) calculates the thickness of the thermal barrier coating using a custom function formula, specifically including the following steps: S31. Define a custom function f(x), where the variable x is the comprehensive calculated value of the electron beam process parameters, i.e., power * time; S32. Establish a linear regression model using the INTERCEPT function. The model formula is y = INTERCEPT + B1*x + B2*x^2. 2 +B3*x^ 3 B1, B2, and B3 are all fitting coefficients; S33. By comparing the physical and chemical properties of the actual target material (6) with those of the standard target material, the physical and chemical properties include chemical composition, target material density, size and porosity, the target material coefficient a is determined based on the above values. S34. Determine the power coefficient b based on the power value in the electron beam process parameters; S35. Calculate the function f(x) = y * a * b; S36. Determine the deposition coefficient c based on the workpiece type and deposition temperature value; S37. The mass z consumed by the target material is obtained by the weighing sensor (8), and the above data is transmitted to the computer (11) via the data cable (9). S38. Calculate h=[z / f(x)]*c to obtain the calculated coating thickness.

2. The method for monitoring the thickness of electron beam physical vapor deposition thermal barrier coatings according to claim 1, characterized in that, The target material (6) is a ceramic target material of yttrium oxide-stabilized zirconium oxide or a thermal barrier coating target material of other component systems.

3. The method for monitoring the thickness of electron beam physical vapor deposition thermal barrier coatings according to claim 1, characterized in that, The electron beam emitting device (10) is configured as a direct-fire electron gun or a deflection electron gun with a deflection angle of 0-270°, and the power range of the electron gun is 5~60KW.

4. The method for monitoring the thickness of electron beam physical vapor deposition thermal barrier coatings according to claim 1, characterized in that, Before the process preparation operation in step S2, the target material (6) needs to be preheated. The preheating treatment uses a low-power electron beam.

5. The method for monitoring the thickness of electron beam physical vapor deposition thermal barrier coatings according to claim 1, characterized in that, The time in step S31 is obtained through a timer, and the unit of time is minutes.

6. The method for monitoring the thickness of an electron beam physical vapor deposition thermal barrier coating according to claim 1, characterized in that, The fitting coefficients in step S32 are set to B1≥B2≥B3.

7. The method for monitoring the thickness of electron beam physical vapor deposition thermal barrier coatings according to claim 1, characterized in that, The numerical range of the target coefficient 'a' in step S33 is 0.80 ≤ a ≤ 1.

2.

8. The method for monitoring the thickness of an electron beam physical vapor deposition thermal barrier coating according to claim 1, characterized in that, The power coefficient b in step S34 has a value range of 0.7 ≤ b ≤ 1.

2.

9. The method for monitoring the thickness of an electron beam physical vapor deposition thermal barrier coating according to claim 1, characterized in that, The deposition coefficient c in step S36 has a value range of 0.7 ≤ c ≤ 1.8.

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