Method for quickly verifying service life of thermal barrier coating

Abstract

The invention provides a method for quickly verifying the service life of a thermal barrier coating, which sequentially comprises the following steps of: preparing a to-be-tested sample coated with the thermal barrier coating which comprises a ceramic layer and a bonding layer which are fixedly combined; putting the to-be-tested sample into a heat treatment device, and carrying out heat preservation for preset heat treatment time at a preset heat treatment temperature, so that a TGO layer is thermally grown in the thermal barrier coating of the to-be-tested sample; and performing performance examination test on the to-be-tested sample to verify the service life of the thermal barrier coating of the to-be-tested sample. According to the method, before the performance assessment test is carried out on the to-be-tested sample of the thermal barrier coating, the thicker TGO layer is prefabricated between the ceramic layer and the bonding layer of the to-be-tested sample, so that the long part of the growth of the TGO layer in the to-be-tested sample before the performance assessment test is effectively shortened, the test resource is used in the stage that the thicker TGO layer of the relatively fragile thermal barrier coating, and the test efficiency is improved. The relative performance examination time of the comparison sample is greatly shortened, and the screening and examination progress is accelerated.

Description

Technical Field

[0001] The invention relates to the technical field of thermal barrier coating detection, and in particular to a method for quickly verifying the life of a thermal barrier coating. Background Art

[0002] The development of industries such as aerospace, energy and power has put forward higher and higher requirements for aircraft engines and gas turbines. In order to improve the high temperature resistance of high temperature components (including but not limited to turbine blades, turbine guide rings, combustion chamber components, etc.), in addition to upgrading the base material and improving the cooling method, the corresponding thermal barrier coating (TBC) is usually sprayed on the surface of the base material. At present, the most widely used thermal barrier coating materials include a top layer composed of a ceramic layer and a bottom layer composed of a bonding layer. The ceramic layer can be partially yttria-doped zirconia (PYSZ for short), or other types of ceramic layers. The bonding layer can be MCrAlY (M represents Co and / or Ni elements).

[0003] Due to the harsh working conditions of high-temperature components, the newly designed thermal barrier coating system needs to be verified in detail before it can be applied in actual units. Conventional performance assessment methods for thermal barrier coatings include but are not limited to physical parameter determination, oxidation resistance test, furnace cycle test, flame / laser thermal shock test, corrosion resistance, etc., which are used to fully assess the service life of thermal barrier coatings under high temperature, hot and cold cycles, temperature changes, etc., to provide guarantee for the safe application of thermal barrier coatings.

[0004] Among the performance assessment methods for thermal barrier coatings, the most important are cyclic tests that have both high temperature and cycles, including furnace cycle tests and flame / laser thermal shock tests. At the same time, since the entire test piece is at a uniform temperature during the furnace cycle test, the flame / laser thermal shock test has become the test that best simulates actual service conditions. However, the test cycle of the flame / laser thermal shock test is often very long. In order to simulate actual working conditions, the surface ceramic layer is usually heated to above 1200°C, and cooling gas is blown on the back. It consumes a lot of energy and takes a long time. It takes one to two months to get the test results for a set of test samples, and the cost is extremely high, which ultimately greatly limits the development efficiency of thermal barrier coatings.

[0005] According to literature research, the main failure mode of thermal barrier coatings is that when the thermal barrier coatings work in a high temperature environment, the bonding layer is oxidized, and a thermally grown oxide layer (TGO layer) is generated at the interface between the ceramic layer and the bonding layer. The main component of the TGO layer is aluminum oxide (Al2O3). 2 O 3), as the degree of heat exposure increases, the thickness of the TGO layer increases, and its own stress and the alternation of hot and cold during the cycle process will cause tiny cracks to appear at the interface between the ceramic layer and the bonding layer and gradually expand, eventually leading to peeling failure at the interface between the ceramic layer and the bonding layer. However, in the early stage of TGO layer growth and when the TGO layer is relatively thin, it is difficult for cyclic testing to form cracks inside it to cause the thermal barrier coating to peel off. Most cracks are formed after the TGO layer grows to a certain thickness. This is equivalent to the traditional thermal shock test process, in which most of the time in the early stage is spent trying to grow the TGO layer to a certain thickness, and then taking advantage of the fragility of the TGO layer, the thermal barrier coating is tested until it peels off. However, the growth process of the TGO layer in the early stage takes a long time, which makes the entire test cycle very long, which also increases the test cost. Summary of the invention

[0006] In view of the above-mentioned shortcomings of the prior art, the purpose of the present invention is to provide a method for quickly verifying the life of a thermal barrier coating, by prefabricating a thicker TGO layer in the thermal barrier coating of the sample to be tested before the cyclic test, so as to shorten the test period and cost.

[0007] To achieve the above object, the present invention provides a method for quickly verifying the life of a thermal barrier coating, which comprises the following steps in sequence:

[0008] S1. preparing a sample to be tested coated with a thermal barrier coating, wherein the thermal barrier coating comprises a fixedly bonded ceramic layer and a bonding layer;

[0009] S2, placing the sample to be tested into a heat treatment device, maintaining the temperature at a preset heat treatment temperature for a preset heat treatment time, so that a TGO layer is thermally grown in the thermal barrier coating of the sample to be tested, wherein the thickness of the TGO layer is 1-15 μm;

[0010] S3. Performing a performance assessment test on the sample to be tested to verify the life of the thermal barrier coating of the sample to be tested.

[0011] Furthermore, the heat treatment device is a muffle furnace.

[0012] Furthermore, the preset heat treatment temperature is 1050° C. to 1150° C., and the preset heat treatment time is 200 h to 500 h.

[0013] Furthermore, the preset heat treatment temperature is 1100°C to 1150°C.

[0014] Furthermore, the thickness of the TGO layer is 5-10 μm.

[0015] Further, in the step S1, there are multiple samples to be tested;

[0016] In step S2, a plurality of samples to be tested are placed in a heat treatment device at the same time and kept at the same preset heat treatment temperature for a preset heat treatment time.

[0017] Furthermore, the performance assessment test includes a furnace cycle test, a flame thermal shock test, a laser thermal shock test, and a bonding strength test.

[0018] As described above, the method for quickly verifying the life of a thermal barrier coating according to the present invention has the following beneficial effects:

[0019] Before the performance evaluation test of the thermal barrier coating sample to be tested, the present application has prefabricated a thicker TGO layer between the ceramic layer and the bonding layer of the sample to be tested; thus, in the subsequent performance evaluation test, through a simple hot and cold cycle, it is possible to promote the generation of cracks in the thermal barrier coating and gradually expand and grow, eventually causing the thermal barrier coating to fail and peel off, completing the life verification of the thermal barrier coating. Obviously, compared with the prior art, the present application effectively shortens the long part of the growth of the TGO layer in the test sample before the performance evaluation test, that is, effectively simplifies the growth process of the early TGO layer, and uses the test resources in the stage of the TGO layer of the thermal barrier coating being relatively fragile and having a larger thickness, thereby greatly shortening the relative performance evaluation time of the comparison sample and accelerating the screening and evaluation progress. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 Flow chart of the method for rapid verification of thermal barrier coating life for this application.

[0021] Figure 2 This is a schematic diagram of the structure of the sample to be tested in step S1 of this application.

[0022] Figure 3 This is a schematic diagram of the structure of the sample to be tested after step S2 of this application. DETAILED DESCRIPTION

[0023] The following is a description of the implementation of the present invention by means of specific embodiments. Those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification.

[0024] It should be noted that the structures, proportions, sizes, etc. drawn in the drawings of this specification are only used to match the contents disclosed in the specification for people familiar with this technology to understand and read, and are not used to limit the limiting conditions for the implementation of the present invention, so they have no substantial technical significance. Any modification of the structure, change of the proportional relationship or adjustment of the size should still fall within the scope of the technical content disclosed by the present invention without affecting the effects and purposes that can be achieved by the present invention. At the same time, the terms such as "upper", "lower", "left", "right", "middle" and "one" quoted in this specification are only for the convenience of description, and are not used to limit the scope of the implementation of the present invention. The change or adjustment of their relative relationship should also be regarded as the scope of the implementation of the present invention without substantially changing the technical content.

[0025] It should also be noted that when an element is referred to as being "fixed on" or "disposed on" another element, it may be directly on the other element or there may be an intermediate element at the same time. When an element is referred to as being "connected to" another element, it may be directly connected to the other element or may be indirectly connected to the other element through an intermediate element.

[0026] In addition, the technical solutions between the various embodiments can be combined with each other, but they must be based on the fact that they can be implemented by ordinary technicians in this field. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by this application.

[0027] The present application provides a method for quickly verifying the life of a thermal barrier coating, which is used in the development and verification of thermal barrier coating materials. By simplifying the growth process of the early TGO layer, the life of the thermal barrier coating can be verified quickly and at low cost, thereby greatly shortening the test cost and test cycle.

[0028] like Figure 1 As shown, the method for quickly verifying the life of a thermal barrier coating involved in the present application includes the following steps in sequence.

[0029] Step S1, prepare the sample to be tested: Figure 1 As shown, the sample to be tested has been coated with a thermal barrier coating, which includes a fixedly bonded ceramic layer 30 and a bonding layer 20, wherein the bonding layer 20 is a bottom layer of the coating sprayed first on the substrate 10, and the ceramic layer 30 is a top layer of the coating sprayed later. Therefore, the substrate 10 of the sample to be tested must be sprayed with both the bonding layer 20 and the ceramic layer 30, and the samples sprayed with only the bonding layer 20 or only the ceramic layer 30 do not meet the requirements.

[0030] Step S2, placing the sample to be tested in a heat treatment device, which may be a muffle furnace; maintaining the sample at a preset heat treatment temperature for a preset heat treatment time, that is, heat treating the sample to be tested under the preset heat treatment conditions, so that a TGO layer 40 is thermally grown in the thermal barrier coating of the sample to be tested, and the thickness of the TGO layer 40 is 1-15 μm. Figure 3 As shown, the TGO layer 40 is distributed at the interface between the ceramic layer 30 and the bonding layer 20 in the sample to be tested.

[0031] Because the bonding layer 20 in the thermal barrier coating is usually more resistant to oxidation, in order to shorten the time required to form a TGO layer 40 of a fixed thickness, the preset heat treatment temperature is preferably 1050°C to 1150°C, and the preset heat treatment time is preferably 200h to 500h. More preferably, when the preset heat treatment temperature is 1100°C to 1150°C, that is, the preset heat treatment temperature is above 1100°C, for example, oxidation at a temperature of 1100°C for 200h can form a TGO layer 40 with a thickness of about 5-10μm; if the preset heat treatment temperature is relatively low, for example, if a TGO layer 40 with a thickness of about 5-10μm is to be formed at a temperature of 1050°C, oxidation for 500h is required. At the same time, the preset heat treatment temperature cannot be too high. When the preset heat treatment temperature is 1200°C, although the oxidation rate is greatly increased, the growth of the TGO layer 40 during the oxidation process may be uncontrollable, and the substrate 10 of the sample to be tested may also undergo unpredictable structural changes at high temperatures. Therefore, the preset heat treatment temperature is controlled within the range of 1050°C to 1150°C for oxidation, which can quickly prefabricate a high-quality TGO layer 40. Of course, for bonding layers 20 of different materials, the growth rate of the TGO layer 40 will be different, and the heat treatment conditions need to be adjusted according to actual conditions.

[0032] Step S3: Performing a performance assessment test on the sample to be tested, the performance assessment test includes but is not limited to a furnace cycle test, a flame thermal shock test, a laser thermal shock test, and a bonding strength test to verify the life of the thermal barrier coating of the sample to be tested.

[0033] Before the performance evaluation test of the thermal barrier coating sample to be tested, the present application has placed the sample to be tested in a high temperature environment such as a muffle furnace for oxidation for a period of time, and a thicker TGO layer 40 has been prefabricated between the ceramic layer 30 and the bonding layer 20 of the sample to be tested; thus, in the subsequent performance evaluation test, through a simple hot and cold cycle, it is possible to promote the generation of cracks in the thermal barrier coating and gradually expand and grow, eventually causing the thermal barrier coating to fail and peel off, completing the life verification of the thermal barrier coating. Obviously, compared with the prior art, the present application effectively shortens the long part of the growth of the TGO layer 40 in the expected test sample before the performance evaluation test, that is, effectively simplifies the growth process of the TGO layer 40 in the early stage, and uses the test resources to the stage of the TGO layer 40 of the thermal barrier coating, which is relatively fragile and has a larger thickness. The main test is the anti-cracking ability of the TGO layer 40 under cyclic conditions, which can greatly shorten the relative performance evaluation time of the comparison sample, accelerate the screening and evaluation progress, and improve the test efficiency.

[0034] Furthermore, in the above step S1, there are multiple samples to be tested, and the compositions of the bonding layer 20 and the ceramic layer 30 of the multiple samples to be tested may be the same or different, so that multiple samples to be tested with the same bonding layer 20 and different ceramic layers 30 can be tested, or multiple samples to be tested with different bonding layers 20 and different ceramic layers 30 can be tested, or multiple samples to be tested with the same composition of the bonding layer 20 and the ceramic layer 30 but different spraying processes or parameters can be tested; in step S2, the multiple samples to be tested are placed in a heat treatment device at the same time, and kept warm at the same preset heat treatment temperature for a preset heat treatment time. In other words, the present application performs high-temperature oxidation on multiple samples to be tested in the same batch under heat treatment parameters of fixed heat treatment temperature and heat treatment time, prefabricates a thicker TGO layer 40, and then performs cyclic testing. In this way, the furnace temperature and oxidation time for prefabricating the TGO layer 40 of multiple samples to be tested in the same batch are consistent. Since the antioxidant capabilities of the bonding layers 20 with different components are different, the thickness of the TGO layer 40 grown in the same batch of oxidized samples to be tested may be inconsistent; however, as a comparative test, even if the thickness of the TGO layer 40 grown in each sample to be tested is inconsistent, the heating temperature and time of the same batch of comparative tests are unified, which can better perform horizontal comparison.

[0035] Furthermore, in the above step S3, when the performance test is performed on the sample to be tested, the thermal barrier coating is relatively fragile because the TGO layer 40 has reached a certain thickness. In order to better distinguish the performance of different thermal barrier coating samples to be tested, the test intensity can be appropriately reduced. For example, in the flame thermal shock test or the laser thermal shock test, the surface temperature and the insulation time of the sample to be tested can be reduced to provide more economical and fast hot and cold test conditions to evaluate the crack resistance of the TGO layer 40; even multiple samples to be tested can be welded to the same board, and a large area of ​​low-intensity heat source can be used to perform economical and fast hot and cold tests on multiple samples to be tested, so as to achieve the purpose of rapid comparison and screening.

[0036] In summary, the method for quickly verifying the life of thermal barrier coatings involved in the present application has the following advantages.

[0037] 1. In the performance evaluation tests of thermal barrier coatings such as flame thermal shock test and laser thermal shock test, the failure process of thermal barrier coating is mainly divided into two parts: the first part is the growth of TGO layer 40 in thermal barrier coating, and the second part is the growth of TGO layer 40 in thermal barrier coating to a certain thickness, crack initiation and expansion occur, resulting in failure of thermal barrier coating, and the second part is also the critical period of failure of thermal barrier coating. This application prefabricates a thicker TGO layer 40 in the thermal barrier coating of the sample to be tested by placing the sample to be tested in a high temperature environment such as a muffle furnace for oxidation for a period of time, thereby shortening the long first part of the growth of TGO layer 40 in the early stage of the performance evaluation test, and using the test resources in the critical period of failure of thermal barrier coating when the TGO layer 40 is thicker, thereby shortening the performance evaluation test cycle and cost and improving the test efficiency.

[0038] 2. The flame or laser parameters required for the performance assessment test are weakened. This application can measure multiple samples to be tested at a single time, which can not only reduce the energy consumption of the performance assessment test and save costs, but also greatly shorten the assessment time of the relative performance of the comparison samples and accelerate the screening and assessment progress.

[0039] In summary, the present invention effectively overcomes various shortcomings of the prior art and has high industrial utilization value.

[0040] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by a person of ordinary skill in the art without departing from the spirit and technical concept disclosed by the present invention shall still be covered by the claims of the present invention.

Claims

1. A method for quickly verifying the life of a thermal barrier coating, characterized in that: The following steps are included in sequence: S1. preparing a sample to be tested coated with a thermal barrier coating, wherein the thermal barrier coating comprises a fixedly bonded ceramic layer and a bonding layer; S2, placing the sample to be tested into a heat treatment device, maintaining the temperature at a preset heat treatment temperature for a preset heat treatment time, so that a TGO layer is thermally grown in the thermal barrier coating of the sample to be tested, wherein the thickness of the TGO layer is 1-15 μm; S3. Performing a performance assessment test on the sample to be tested to verify the life of the thermal barrier coating of the sample to be tested.

2. The method for quickly verifying the life of a thermal barrier coating according to claim 1, characterized in that: The heat treatment device is a muffle furnace.

3. The method for quickly verifying the life of a thermal barrier coating according to claim 1, characterized in that: The preset heat treatment temperature is 1050° C. to 1150° C., and the preset heat treatment time is 200 h to 500 h.

4. The method for quickly verifying the life of a thermal barrier coating according to claim 3, characterized in that: The preset heat treatment temperature is 1100°C to 1150°C.

5. The method for quickly verifying the life of a thermal barrier coating according to claim 3, characterized in that: The thickness of the TGO layer is 5-10 μm.

6. The method for quickly verifying the life of a thermal barrier coating according to claim 1, characterized in that: In the step S1, there are multiple samples to be tested; In step S2, a plurality of samples to be tested are placed in a heat treatment device at the same time and kept at the same preset heat treatment temperature for a preset heat treatment time.

7. The method for quickly verifying the life of a thermal barrier coating according to claim 1, characterized in that: The performance assessment tests include furnace cycle test, flame thermal shock test, laser thermal shock test and bonding strength test.

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