Sample clamp and method for mechanical coupling failure test of thermal barrier coating

Abstract

The invention discloses a sample clamp and method for a mechanical coupling failure test of a thermal barrier coating, and relates to the technical field of mechanical property testing of high-temperature materials.The sample clamp for the mechanical coupling failure test of the thermal barrier coating comprises a fixing base, and a cavity used for containing a sample is formed in the fixing base; outer fulcrum beams are arranged at the positions, located at the two ends of the cavity, of the fixing base, the two outer fulcrum beams are supported on the edge parts of the two sides of the sample respectively, two inner fulcrum beams are oppositely arranged in the position, located in the middle area of the cavity, of the fixing base, the two inner fulcrum beams are supported in the middle area of the sample, and an adjusting assembly is arranged between the two inner fulcrum beams and the fixing base; and the height of the two inner fulcrum beams in the fixed seat is adjusted. The two outer fulcrum beams, the two inner fulcrum beams and the fixing base are all made of aluminum oxide ceramics, the sample clamp is made of high-strength aluminum oxide ceramics, and a thermal barrier coating sample can be subjected to on-load testing in a high-temperature environment at the temperature of 1600 DEG C or above.

Description

Technical Field

[0001] The present invention relates to the technical field of mechanical property testing of high-temperature materials, and more specifically, to a specimen fixture and method for thermo-mechanical coupling failure testing of thermal barrier coatings. Background Art

[0002] In high-temperature environments, especially in hot-end components such as gas turbines, materials need to withstand high-temperature oxidation, mechanical stress, and thermal stress under extreme conditions. These conditions often lead to damage and failure of thermal barrier coating materials, shortening the service life of the equipment. Therefore, it is crucial to study the failure behavior of thermal barrier coatings under the coupling conditions of high temperature and mechanical load.

[0003] Under high-temperature conditions, the failure of coating materials is usually related to multiple factors, including thermal stress, phase change stress, and the erosion of corrosive media (such as , , ). These complex environmental conditions require experimental equipment to not only apply accurate stress at high temperature but also avoid deformation and failure of the fixture itself at high temperature. In addition, the material of the fixture needs to have excellent oxidation and corrosion resistance to ensure the long-term stability of the experimental process.

[0004] In the prior art, four-point bending stress loading fixtures are usually made of metal materials, but in high-temperature environments above 1600 °C, metal fixtures will undergo thermal expansion, deformation, and even damage, which will not only affect the stability of the load but also lead to experimental failure. In addition, the stress distribution of traditional metal fixtures at high temperature is often uneven, and it is impossible to simulate the stress conditions of coating materials such as gas turbine blades under actual service conditions.

[0005] In summary, how to find a new fixture and method to overcome and break through the obstacles in the research of high-temperature environments, especially in hot-end components such as gas turbines, and solve the limitations of the existing testing methods mentioned above is an urgent problem for those skilled in the art at present. Summary of the Invention

[0006] In view of this, the purpose of the present invention is to provide a specimen fixture and method for thermo-mechanical coupling failure testing of thermal barrier coatings, which can work stably for a long time under high-temperature conditions, ensure uniform stress distribution, and avoid material damage. The aim is to solve the problems of deformation, stress concentration, and short service life that are prone to occur when the existing four-point bending stress loading fixture is used in a high-temperature gas environment, especially for the mechanical property testing of coating materials at high temperature.

[0007] To achieve the above purpose, the present invention provides the following technical solutions:

[0008] A specimen fixture for the thermo-mechanical coupling failure test of a thermal barrier coating, comprising a fixed seat, a chamber for placing a specimen is formed on the fixed seat, outer fulcrum beams are arranged at both ends of the fixed seat located in the chamber, and the two outer fulcrum beams respectively support on both side edge parts of the specimen. Two inner fulcrum beams are oppositely arranged in the middle area of the fixed seat located in the chamber, and the two inner fulcrum beams support on the middle area of the specimen. An adjusting assembly is arranged between the two inner fulcrum beams and the fixed seat to adjust the height of the two inner fulcrum beams located in the fixed seat;

[0009] The two outer fulcrum beams, the two inner fulcrum beams and the fixed seat are all made of alumina ceramics.

[0010] Preferably, the contact surfaces of the two outer fulcrum beams and the specimen are both cylindrical surfaces.

[0011] Preferably, the contact surfaces of the two inner fulcrum beams and the specimen are both cylindrical surfaces.

[0012] Preferably, the adjusting assembly includes an adjusting plate slidably arranged on the fixed seat and connected to the two inner fulcrum beams, and a fixing member is arranged between the adjusting plate and the fixed seat to keep the position of the adjusting plate relative to the fixed seat fixed.

[0013] Preferably, the contact surfaces of the two outer fulcrum beams and the specimen and the contact surfaces of the two inner fulcrum beams and the specimen are both polished.

[0014] A test method for the thermo-mechanical coupling failure test of a thermal barrier coating, applying the specimen fixture for the thermo-mechanical coupling failure test of a thermal barrier coating described in any one of the above, the test method includes:

[0015] Before the experiment, ultrasonic degreasing and cleaning are carried out on the specimen, a NiCoCrAlY bonding layer and a YSZ ceramic layer are sequentially prepared on the surface of the specimen, and the NiCoCrAlY bonding layer is bonded between the surface of the specimen and the YSZ ceramic layer;

[0016] Place the specimen with the YSZ ceramic layer prepared thereon between the two outer fulcrum beams and the two inner fulcrum beams, and the coated surface of the specimen is located on the outside;

[0017] Adjust the height of the two inner fulcrum beams to meet the load requirements of the experiment, and calculate the stress borne by the specimen;

[0018] Place the specimen fixture with the specimen installed therein in a high-temperature furnace at 1100 °C for the experiment;

[0019] Obtain the damage law and cracking behavior of the specimen for data analysis.

[0020] Preferably, the method for preparing the NiCoCrAlY bonding layer on the surface of the specimen is as follows:

[0021] The NiCoCrAlY bonding layer is prepared on the surface of the specimen by supersonic spraying technology, and the thickness is 180 - 230 .

[0022] Preferably, the method for preparing the YSZ ceramic layer on the surface of the specimen is as follows:

[0023] The YSZ ceramic layer is prepared on the surface of the specimen by atmospheric plasma spraying process, and the thickness is 400 - 500 .

[0024] Preferably, the calculation of the stress on the specimen includes:

[0025] Calculating according to the formula:

[0026]

[0027] In the formula: is the stress applied at the center of the surface of the specimen; is the elastic modulus; is the thickness of the specimen; is the deflection; is the distance between the two outer fulcrum beams; is the distance between the outer fulcrum beam and the inner fulcrum beam on the same side.

[0028] Preferably, the specific method of data analysis includes: analyzing the damage law and cracking behavior of the specimen through equipment such as a scanning electron microscope (SEM) and X-ray diffraction (XRD).

[0029] The specimen fixture and method for the thermo-mechanical coupling failure test of the thermal barrier coating provided by the present invention, wherein the specimen fixture is made of high-strength alumina ceramic and can perform a loaded test on the thermal barrier coating specimen in a high-temperature environment above 1600 °C. And this fixture has a design for adjusting the height of the inner fulcrum beam, and the deformation degree of the specimen can be controlled by adjusting the height of the inner fulcrum beam, thereby precisely controlling the magnitude of the applied load, and is applicable to tests under various load states.

[0030] In the further solution provided by this application, at least one of the following beneficial technical effects can also be achieved:

[0031] Adopting precision machining technology, the friction between the fixture and the specimen is reduced by polishing, the surface of the specimen is protected from damage, and the accuracy of the test is improved;

[0032] With the cylindrical surface line contact structure, it is ensured that the stress distribution is uniform when the load is applied, local stress concentration is avoided, and the accuracy of the experimental results is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only the embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained according to the provided drawings without creative efforts.

[0034] Figure 1 It is a schematic diagram of the overall structure of the specimen fixture in this embodiment.

[0035] The reference numerals include:

[0036] 1. Fixed seat; 2. Outer fulcrum beam; 3. Inner fulcrum beam; 4. Chamber; 5. Specimen; 6. Adjusting plate. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0037] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0038] Unless otherwise defined, the technical terms or scientific terms used in the disclosure of this application should have the ordinary meaning understood by those of ordinary skill in the art to which the present invention belongs. The "first", "second" and similar terms used in the present invention do not indicate any order, quantity or importance. "Connection" or "connected" and similar terms are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "Upper", "lower", "left", "right", etc. are only used to represent relative position relationships. When the absolute position of the object being described changes, the relative position relationship can also change accordingly. This application embodiment discloses a specimen fixture and method for thermo-mechanical coupling failure testing of thermal barrier coatings.

[0039] The core of the present invention is to provide a specimen fixture for thermo-mechanical coupling failure testing of thermal barrier coatings.

[0040] Another core of the present invention is to provide a testing method for thermo-mechanical coupling failure testing of thermal barrier coatings, applying the above-mentioned specimen fixture for thermo-mechanical coupling failure testing of thermal barrier coatings.

[0041] Please refer to Figure 1 .

[0042] The specimen fixture for the thermo-mechanical coupling failure test of the thermal barrier coating provided by the present invention includes a fixed seat 1, a chamber 4 for placing a specimen 5 is formed on the fixed seat 1, and outer fulcrum beams 2 are arranged at both ends of the fixed seat 1 located in the chamber 4. The two outer fulcrum beams 2 respectively support the two side edge parts of the specimen 5. Two inner fulcrum beams 3 are oppositely arranged in the middle area of the chamber 4 of the fixed seat 1. The two inner fulcrum beams 3 support the middle area of the specimen 5. An adjusting assembly is arranged between the two inner fulcrum beams 3 and the fixed seat 1 to adjust the height of the two inner fulcrum beams 3 located in the fixed seat 1. The two outer fulcrum beams 2, the two inner fulcrum beams 3 and the fixed seat 1 are all made of alumina ceramics.

[0043] Specifically, the fixed seat 1 is provided with a groove with an inverted T-shaped cross-section along the thickness direction of the specimen 5, and this groove is the so-called chamber 4. The two outer fulcrum beams 2, the two inner fulcrum beams 3 and the specimen 5 are all arranged in the space of the chamber 4. The specimen 5 is placed on the two outer fulcrum beams 2 and the two inner fulcrum beams 3, so that the specimen 5 forms a bent state. Taking the side of the specimen 5 with the coating layer as the upper part and the other side as the lower part, then the two outer fulcrum beams 2 support the upper part of the specimen 5, and the two inner fulcrum beams 3 support the lower part of the specimen 5. And the two outer fulcrum beams 2 respectively support the two sides of the specimen 5, while the two inner fulcrum beams 3 relatively support two parts in the middle of the specimen 5. When the height of the inner fulcrum beam 3 is adjusted through the adjusting assembly, the stress received by the specimen 5 is changed, so as to realize the flexible adjustment of different stresses and meet various mechanical test conditions.

[0044] In this application, the two outer fulcrum beams 2, the two inner fulcrum beams 3 and the fixed seat 1 are all made of alumina ceramics, so that the two outer fulcrum beams 2, the two inner fulcrum beams 3 and the fixed seat 1 all have high heat resistance and can withstand a high-temperature environment above 1600 °C, enabling them to work stably for a long time under high-temperature conditions, ensuring uniform stress distribution of the specimen 5 and avoiding material damage. At the same time, the alumina ceramic material also has oxidation resistance and corrosion resistance, and can cope with complex gases and corrosive media in a simulated gas environment.

[0045] It should be noted that the distance between each group of outer fulcrum beams 2 and inner fulcrum beams 3 on the same side can be specifically determined according to the size of the specimen 5 to achieve precise stress loading and ensure that the specimen fixture is suitable for different specimen sizes.

[0046] The above-mentioned specimen fixture for the thermo-mechanical coupling failure test of the thermal barrier coating is made of high-strength alumina ceramics and can perform a loaded test on the thermal barrier coating specimen in a high-temperature environment above 1600 °C. And this fixture has a design that can adjust the height of the inner fulcrum beam 3. The deformation degree of the specimen can be controlled by adjusting the height of the inner fulcrum beam 3, and then the magnitude of the applied load can be accurately controlled, which is suitable for tests under various load states.

[0047] It should be noted that the inner fulcrum beam 3 can adopt a replaceable component design, so as to be able to achieve a variety of different loading states, including the free state, the low-load state and the high-load state, so as to meet the stress loading requirements under different experimental conditions.

[0048] The specimen fixture and method for the thermo-mechanical coupling failure test of thermal barrier coatings provided by the present invention will be introduced in more detail below with reference to the accompanying drawings and specific embodiments.

[0049] In a specific embodiment, referring to Figure 1 , the contact surfaces of the two outer fulcrum beams 2 and the specimen 5 are both cylindrical surfaces.

[0050] Specifically, the contact surface is set as a cylindrical surface, so as to ensure that when the outer fulcrum beam 2 and the specimen 5 apply a load, the contact part is a line contact. Compared with the plane contact, the stress distribution is more uniform, avoiding the premature failure of the specimen 5 at the contact part due to excessive local stress, so as to more accurately simulate the stress situation of the thermal barrier coating in actual use. At the same time, the cylindrical surface contact also has good self-adaptability. Due to certain dimensional deviations that may exist in the manufacturing process of the specimen 5, or due to dimensional changes caused by thermal expansion, etc. during the test, the cylindrical surface can automatically adjust the contact state with the specimen 5 to ensure that the outer fulcrum beam 2 always stably supports the specimen 5 and ensure the accuracy and reliability of the test results.

[0051] In a specific embodiment, referring to Figure 1 , the contact surfaces of the two inner fulcrum beams 3 and the specimen 5 are both cylindrical surfaces.

[0052] Specifically, the setting of the contact surface between the above-mentioned outer fulcrum beam 2 and the specimen 5 is the same, so that the contact part between the two is a line contact, and has the same effect as above.

[0053] On the basis of any of the above embodiments, referring to Figure 1 , the contact surfaces of the two outer fulcrum beams 2 and the specimen 5 and the contact surfaces of the two inner fulcrum beams 3 and the specimen 5 are both polished to reduce the friction force and avoid stress concentration during the loading process, ensure that the surface of the specimen is not damaged, and at the same time increase the stability between the specimen and the fulcrum.

[0054] Specifically, from the perspective of mechanical property testing, the polished contact surface can greatly improve the contact accuracy. When the outer fulcrum beam 2 contacts the specimen 5 and the inner fulcrum beam 3 contacts the specimen 5, the smooth contact surface can ensure a more uniform and accurate stress distribution. At the microscopic level, the unpolished surface may have tiny unevenness, and these tiny defects will cause stress concentration in local areas, resulting in a deviation between the stress state of the specimen 5 during the test and the actual situation. Through polishing treatment, these microscopic defects can be eliminated, making the contact between the fulcrum beam and the specimen closer and smoother, so that the stress borne by the specimen 5 is closer to the theoretical value and the accuracy of the test results is improved.

[0055] Moreover, in the thermo-mechanical coupling failure test of the thermal barrier coating, complex environments such as high temperature and chemical corrosion are involved. The polished contact surface helps to reduce the adhesion of impurities and corrosive media. The smooth surface is not conducive to the deposition of impurity particles and also reduces the contact area between the corrosive medium and the contact surface, thus slowing down the damage and performance degradation of the contact surface caused by impurities and corrosion. This is particularly important for long-term and multi-cycle tests, which can ensure that the specimen fixture maintains good performance throughout the test and ensure the reliability and stability of the test data.

[0056] At the same time, for the contact surface between the outer fulcrum beam 2 and the specimen 5, the polishing treatment can further optimize the performance of its cylindrical surface. Due to the self-adaptability of the cylindrical surface contact itself, the polished cylindrical surface can better fit the specimen 5. When the specimen 5 undergoes dimensional changes due to thermal expansion or other factors, it can adjust the contact state more smoothly, reducing the friction force and stress fluctuations caused by poor contact. This is not only beneficial to protecting the surface coating of the specimen 5 from damage but also improving the stability of the specimen fixture during the test. For the contact surface between the inner fulcrum beam 3 and the specimen 5, the polishing treatment can reduce the friction force between the contact surfaces, making the adjustment of the height of the inner fulcrum beam 3 smoother. When adjusting the height of the inner fulcrum beam 3 through the adjustment component, if the contact surface is rough, it will increase the resistance during the adjustment process and may even lead to inaccurate adjustment. The polished contact surface can reduce this resistance, making the adjustment process more precise and flexible, so that the stress borne by the specimen 5 can be more accurately controlled.

[0057] It should be noted that appropriate processes and polishing materials are required for the polishing treatment. For example, polishing paste with uniform particle size can be selected and polished with a soft polishing cloth. During the polishing process, the pressure and speed should be controlled to avoid over-polishing, which may cause changes in the contact surface size or surface damage. At the same time, after polishing, the contact surface also needs to be cleaned to remove the residual polishing paste and impurities to ensure the cleanliness of the contact surface.

[0058] Based on any of the above embodiments, refer to Figure 1, The adjusting assembly includes an adjusting plate 6 slidably arranged on the fixed seat 1 and connected to two inner fulcrum beams 3. A fixing member is arranged between the adjusting plate 6 and the fixed seat 1 to keep the position of the adjusting plate 6 relative to the fixed seat 1 fixed.

[0059] Specifically, the adjusting plate 6 provides a way to adjust the height of the inner fulcrum beam 3. The adjusting plate 6 is slidably connected to the fixed seat 1 through the slide rail or chute structure thereon. This slidable connection enables the adjusting plate 6 to move smoothly on the fixed seat 1 along the thickness direction perpendicular to the specimen 5. The two inner fulcrum beams 3 are fixedly connected to the adjusting plate 6. When the adjusting plate 6 moves, it will drive the inner fulcrum beam 3 to move synchronously, thereby changing the height of the inner fulcrum beam 3 in the fixed seat 1.

[0060] The function of the fixing member is to ensure that the adjusting plate 6 can be stably fixed on the fixed seat 1 after being adjusted to the required position. The fixing member can adopt various structural forms, such as a bolt-nut combination. Corresponding threaded holes are respectively arranged on the adjusting plate 6 and the fixed seat 1. When the adjusting plate 6 moves to the appropriate position, the bolt is passed through the threaded hole, and then the nut is tightened to generate sufficient friction between the adjusting plate 6 and the fixed seat 1 to prevent the adjusting plate 6 from sliding during the test and ensure that the height of the inner fulcrum beam 3 remains stable.

[0061] In this embodiment, the specimen 5 used is usually a DZ411 nickel-based alloy specimen, and its dimensions are usually 100mm×10mm×1mm, where the working area is in the area of 40mm×10mm between the two inner fulcrums. On this basis, the distance between the two outer fulcrum beams 2 is 65 - 75mm to ensure that the specimen can uniformly bear the stress. The distance between the inner fulcrum beam 3 and the outer fulcrum beam 2 on the same side is 5 - 15mm, so that the loading stress can be accurately transmitted to the middle area of the specimen.

[0062] It should be noted that the overall design of the above specimen fixture complies with the standards of ASTM G39 - 2016 and GB / T 15970.2 - 2000, and can provide a standardized stress loading mode during the experiment.

[0063] A test method for the thermo-mechanical coupling failure test of thermal barrier coatings provided by the present invention uses the above-mentioned specimen fixture for the thermo-mechanical coupling failure test of thermal barrier coatings. The test method includes:

[0064] Before the experiment, the specimen 5 is ultrasonically degreased and cleaned, and a NiCoCrAlY bonding layer and a YSZ ceramic layer are successively prepared on the surface of the specimen 5, and the NiCoCrAlY bonding layer is bonded between the surface of the specimen 5 and the YSZ ceramic layer;

[0065] Place the specimen 5 with the YSZ ceramic layer between two outer support beams 2 and two inner support beams 3, and the coated surface of the specimen 5 is on the outside;

[0066] Adjust the height of the two inner support beams 3 to meet the load requirements for the experiment, and calculate the stress on the specimen 5;

[0067] Place the specimen fixture with the specimen 5 installed in a high-temperature furnace at 1100 °C for the experiment;

[0068] Obtain the damage law and cracking behavior of the specimen 5 for data analysis.

[0069] Specifically, ultrasonic degreasing can utilize the cavitation effect of ultrasonic waves to effectively remove impurities such as residual grease and dirt on the surface of the specimen 5, while the cleaning process can further remove tiny particles and chemical substances on the surface, ensuring that the surface of the specimen 5 is clean and smooth, providing good substrate conditions for subsequent coating preparation. A NiCoCrAlY bonding layer is prepared on the surface of the specimen 5. This bonding layer has good oxidation resistance, corrosion resistance and bonding force with the substrate, which can enhance the bonding strength between the YSZ ceramic layer and the substrate of the specimen 5 and improve the overall performance of the thermal barrier coating. The subsequently prepared YSZ ceramic layer serves as the main functional layer of the thermal barrier coating, playing roles such as heat insulation and oxidation resistance.

[0070] When placing the specimen 5 with the YSZ ceramic layer between two outer support beams 2 and two inner support beams 3, ensure that the coated surface of the specimen 5 is on the outside, so that during the test, the coated surface of the specimen 5 can directly withstand the high temperature, corrosion, etc. in the simulated actual working environment, more truly reflecting the performance of the thermal barrier coating in actual use.

[0071] Adjust the height of the two inner support beams 3 to achieve different stress loadings. By adjusting the height of the inner support beams 3, the bending degree of the specimen 5 can be changed, thereby controlling the stress magnitude on the specimen 5. During the adjustment process, the operator can accurately adjust the inner support beams 3 to the specified position according to the load requirements for the experiment, in combination with the scale markings or other positioning devices on the specimen fixture. At the same time, calculate the stress on the specimen 5, which can be calculated by deriving a formula. This formula can be derived based on parameters such as the size, material properties of the specimen 5 and the height of the inner support beams 3, ensuring the accuracy and reliability of the stress calculation.

[0072] Place the specimen fixture with specimen 5 in a high-temperature furnace at 1100 °C to conduct experiments, simulating the service conditions of the thermal barrier coating in the actual high-temperature working environment. In the high-temperature furnace, specimen 5 will not only be affected by high temperature but also may be influenced by factors such as chemical corrosion in the furnace atmosphere, thereby realizing the force-chemistry coupling failure test. During the experiment, different experimental times and temperature cycle conditions can be set to study the performance changes of the thermal barrier coating under different working conditions.

[0073] By using detection means, conduct microstructure analysis and composition detection on specimen 5 after the experiment, and observe the damage morphology, crack distribution, and element diffusion on the coating surface, etc. At the same time, combined with the mechanical property test results, analyze the damage law and cracking behavior of specimen 5 under different stress, temperature, and chemical corrosion conditions, and reveal the mechanism of force-chemistry coupling failure of the thermal barrier coating.

[0074] The above test method for the force-chemistry coupling failure test of the thermal barrier coating effectively solves the deficiencies existing in the traditional test methods. The traditional methods may not be able to accurately simulate the stress state and working environment of the thermal barrier coating in actual use, resulting in a large deviation between the test results and the actual situation. However, the test method of the present invention can flexibly control and accurately load the stress of specimen 5 by adopting a reasonable specimen fixture structure and stress adjustment method, and at the same time simulate complex environments such as high temperature and corrosion, providing a more scientific and reliable means for the research on the force-chemistry coupling failure of the thermal barrier coating. Through this method, the failure mechanism of the thermal barrier coating can be deeply understood, providing an important basis for the performance optimization and life prediction of the thermal barrier coating, and promoting the wide application of thermal barrier coating technology in the fields of aerospace, energy and power, etc.

[0075] Based on any one of the above embodiments, the method for preparing the NiCoCrAlY bonding layer on the surface of specimen 5 is: adopt the supersonic spraying technology to prepare the NiCoCrAlY bonding layer on the surface of specimen 5, and the thickness is 180 - 230 .

[0076] Specifically, the supersonic spraying technology is an advanced thermal spraying process. It uses a supersonic gas flow to accelerate the spraying powder to an extremely high speed and then makes it impact the surface of specimen 5 to form a dense coating. During the spraying process, parameters such as spraying distance, spraying angle, powder feeding amount, and gas flow rate will have a significant impact on the thickness, density, and bonding strength of the coating. For example, too close spraying distance may lead to too thick and uneven coating, and even the phenomenon of coating peeling; too far spraying distance will make the kinetic energy of the powder insufficient and it is difficult to form a dense coating. Therefore, a large number of experiments and optimizations are required to determine the best combination of spraying parameters to ensure that the thickness of the NiCoCrAlY bonding layer can be accurately controlled within 180 - 230 Among them. By using the supersonic spraying technology to prepare the NiCoCrAlY bonding layer and strictly controlling various parameters and quality inspection links in the preparation process, a high-quality and high-performance bonding layer can be prepared, providing a solid foundation for the subsequent preparation of the YSZ ceramic layer and the thermo-mechanical coupling failure test of the thermal barrier coating. This bonding layer has good oxidation resistance, corrosion resistance and bonding force with the substrate, which can effectively improve the overall performance and reliability of the thermal barrier coating and extend the service life of the thermal barrier coating.

[0077] Based on any one of the above embodiments, the method for preparing the YSZ ceramic layer on the surface of Specimen 5 is: preparing the YSZ ceramic layer on the surface of Specimen 5 by atmospheric plasma spraying process, and the thickness is 400 - 500 .

[0078] Specifically, the high temperature generated by the plasma arc can instantaneously heat the YSZ ceramic powder to the molten or semi-molten state, so that the powder particles impact the surface of Specimen 5 at an extremely high speed. This process of high-speed impact and rapid cooling makes the coating have a unique microstructure. At the microscopic level, the coating is composed of countless fine YSZ ceramic particles stacked and embedded with each other. There is a certain bond between the particles, but a certain pore structure is retained. These pores can relieve the thermal stress generated during the thermal cycle of the coating to a certain extent and improve the thermal shock resistance of the coating. Usually, argon, hydrogen, etc. are selected as plasma gases. Argon has good stability and can ensure the stable combustion of the plasma arc; hydrogen can increase the temperature of the plasma arc, enabling the YSZ ceramic powder to be more fully melted.

[0079] It should be noted that in order to ensure that the thickness of the YSZ ceramic layer can be accurately controlled within 400 - 500 , an on-line monitoring system can be adopted during the spraying process. This system can monitor the thickness of the coating in real time and feed the data back to the control system of the spraying equipment. The operator can adjust the spraying parameters, such as powder feeding amount, spraying speed, etc., in a timely manner according to the feedback data to ensure that the coating thickness always remains within the designed range. At the same time, before spraying, a detailed spraying path plan will be formulated according to the size and shape of Specimen 5 to ensure that the entire surface of Specimen 5 can obtain a uniform and consistent coating thickness.

[0080] For the YSZ ceramic layer prepared as above, its thickness is 400 - 500 Its thickness can provide good heat insulation effect and effectively reduce the temperature on the surface of specimen 5; good oxidation resistance and corrosion resistance can protect specimen 5 for long-term use in high-temperature and corrosive environments; the tight bonding with the NiCoCrAlY bonding layer ensures the stability and reliability of the entire thermal barrier coating system. This YSZ ceramic layer provides a reliable guarantee for the thermo-mechanical coupling failure test of the thermal barrier coating, which helps to more accurately study the failure mechanism and performance change law of the thermal barrier coating.

[0081] Based on any one of the above embodiments, the stress applied to specimen 5 is calculated, including calculating according to the formula:

[0082]

[0083] In the formula: is the stress applied to the center of the surface of specimen 5; is the elastic modulus; is the thickness of specimen 5; is the deflection; is the distance between the two outer support beams 2; is the distance between the outer support beam 2 and the inner support beam 3 on the same side.

[0084] Through the above formula, the stress applied to the center of the surface of specimen 5 can be accurately calculated. By adjusting the height of the inner support beam 3 and changing the value of the deflection , the precise control of the stress applied to specimen 5 can be achieved. This is of great significance for studying the thermo-mechanical coupling failure mechanism of the thermal barrier coating under different stress conditions. At the same time, this formula also provides a theoretical basis for the analysis and processing of experimental data, which helps to more deeply understand the performance change law of the thermal barrier coating. For example, when conducting a series of thermo-mechanical coupling failure tests of the thermal barrier coating at different stress levels, the stress value applied to specimen 5 at each stress level can be calculated according to the formula, and then the experimental results can be compared and analyzed with the theoretical calculated values to verify the accuracy and reliability of the formula. At the same time, by studying the damage law and cracking behavior of the thermal barrier coating under different stress conditions, the internal mechanism of the failure of the thermal barrier coating can be revealed, which provides an important reference for the performance optimization and life prediction of the thermal barrier coating.

[0085] Based on any one of the above embodiments, the specific method of data analysis includes: analyzing the damage law and cracking behavior of specimen 5 through equipment such as scanning electron microscope (SEM) and X-ray diffraction (XRD).

[0086] Specifically, in the experiment, the damage behavior of the specimen was mainly reflected in the cracking and spalling of the coating surface. Through high-magnification microscope observation, it was found that under the unloaded state, the surface of the specimen remained in good integrity, while under the loaded condition, especially in the high-load state, vertical cracks appeared on the coating surface, and the cracks propagated vertically along the stress direction, eventually leading to the spalling of the coating. The force-chemical coupling failure test was carried out on the DZ411 specimen with coating by a four-point bending stress loading fixture. The results showed that under the loaded condition, the cracks on the specimen surface increased significantly, and the propagation direction of the cracks was perpendicular to the stress direction, proving that the external load had a significant impact on the coating damage.

[0087] In this specification, each embodiment is described in a progressive manner. The key point of each embodiment is to illustrate the differences from other embodiments. For the same or similar parts among the embodiments, reference can be made to each other.

[0088] The above has introduced in detail a specimen fixture and method for the force-chemical coupling failure test of thermal barrier coatings provided by the present invention. Specific examples are used in this article to elaborate on the principle and implementation manner of the present invention. The description of the above embodiments is only used to help understand the method and its core idea of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and modifications can be made to the present invention, and these improvements and modifications also fall within the protection scope of the present invention.

Claims

1. A sample fixture for mechanical coupling failure test of thermal barrier coatings, characterized in that: The invention comprises a fixing seat (1), wherein a chamber (4) for placing a sample (5) is formed on the fixing seat (1), and outer supporting beams (2) are arranged at both ends of the fixing seat (1) located in the chamber (4), and the two outer supporting beams (2) are respectively supported on the edge portions of both sides of the sample (5), and the fixing seat (1) is located in the middle area of ​​the chamber (4) and has two inner supporting beams (3) arranged opposite to each other, and the two inner supporting beams (3) are supported on the middle area of ​​the sample (5), and an adjustment component is arranged between the two inner supporting beams (3) and the fixing seat (1) to adjust the height of the two inner supporting beams (3) in the fixing seat (1); The two outer fulcrum beams (2), the two inner fulcrum beams (3) and the fixing seat (1) are all made of alumina ceramics.

2. A sample fixture for mechanical-chemical coupling failure test of thermal barrier coatings according to claim 1, characterized in that: The contact surfaces between the two outer support beams (2) and the sample (5) are both cylindrical surfaces.

3. The sample fixture for mechanical-chemical coupling failure test of thermal barrier coating according to claim 1, characterized in that: The contact surfaces between the two inner support beams (3) and the sample (5) are both cylindrical surfaces.

4. A sample fixture for mechanical-chemical coupling failure test of thermal barrier coatings according to any one of claims 1 to 3, characterized in that: The adjustment assembly comprises an adjustment plate (6) slidably arranged on the fixing seat (1) and connected to the two inner support beams (3); a fixing member is arranged between the adjustment plate (6) and the fixing seat (1) so that the position of the adjustment plate (6) relative to the fixing seat (1) remains fixed.

5. A sample fixture for mechanical-chemical coupling failure test of thermal barrier coatings according to any one of claims 1 to 3, characterized in that: The contact surfaces between the two outer support beams (2) and the sample (5) and the contact surfaces between the two inner support beams (3) and the sample (5) are polished.

6. A test method for mechanical-chemical coupling failure test of thermal barrier coatings, characterized in that: Using a sample fixture for mechanical coupling failure test of thermal barrier coatings as described in any one of claims 1 to 5, the test method comprises: Before the experiment, the sample (5) is ultrasonically degreased and cleaned, and a NiCoCrAlY bonding layer and a YSZ ceramic layer are sequentially prepared on the surface of the sample (5), and the NiCoCrAlY bonding layer is bonded between the surface of the sample (5) and the YSZ ceramic layer; The sample (5) prepared with the YSZ ceramic layer is placed between the two outer support beams (2) and the two inner support beams (3), with the coating surface of the sample (5) located on the outside; Adjusting the heights of the two inner support beams (3) to achieve the load requirements of the experiment, and calculating the stress on the sample (5); Placing the sample fixture with the sample (5) installed in a high-temperature furnace at 1100° C. to conduct an experiment; The damage pattern and cracking behavior of the sample (5) are obtained for data analysis.

7. A test method for mechanical-chemical coupling failure test of thermal barrier coatings according to claim 6, characterized in that: The method for preparing the NiCoCrAlY bonding layer on the surface of the sample (5) is: A NiCoCrAlY bonding layer with a thickness of 180 to 230 mm is prepared on the surface of the sample (5) by supersonic spraying technology. .

8. The test method for mechanical-chemical coupling failure test of thermal barrier coating according to claim 6, characterized in that: The method for preparing the YSZ ceramic layer on the surface of the sample (5) is: A YSZ ceramic layer is prepared on the surface of the sample (5) by an atmospheric plasma spraying process, and the thickness is 400-500 .

9. A test method for mechanical-chemical coupling failure test of thermal barrier coatings according to claim 6, characterized in that: Calculating the stress on the sample (5) includes: Calculate according to the formula: Where: is the stress applied at the center of the surface of the specimen (5); is the elastic modulus; is the thickness of the sample (5); is the deflection; is the distance between the two outer support beams (2); is the distance between the outer support beam (2) and the inner support beam (3) on the same side.

10. A test method for mechanical-chemical coupling failure test of thermal barrier coatings according to claim 6, characterized in that: The specific method of data analysis includes: analyzing the damage pattern and cracking behavior of the sample (5) by scanning electron microscope and X-ray diffraction equipment.

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