Test method for evaluating reliability of EBPVD (electron beam physical vapor deposition) coating of turbine blade of gas turbine

Abstract

The invention provides a test method for evaluating the reliability of an EBPVD (electron beam physical vapor deposition) coating of a turbine blade of a gas turbine, which is characterized by comprising the following steps: acquiring a test blade, and coating the surface of the test blade with an EBPVD thermal barrier coating to be tested; the test blade is fixed through the supporting tool; spraying a flame flow containing particles to the surface of the test blade by using a supersonic flame gun, and simulating the working conditions of gas scouring and particle erosion; the failure form of the thermal barrier coating is observed, and testing times are recorded; and judging the reliability of the thermal barrier coating according to the failure form and the test count. According to the testing method, high-temperature and high-speed fuel gas is obtained, and the fuel gas is washed by particles and is closer to a real fuel gas incoming flow state. The high velocity oxy-fuel spray gun sprays emery to impact the blade coating area, the technological process is simpler and more efficient, the testing period is short, and the judgment standard of reliability evaluation is simple and direct.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of gas turbine turbine blade thermal barrier coating reliability testing, and particularly relates to a test method for evaluating the reliability of a gas turbine turbine blade EBPVD coating. BACKGROUND

[0002] With the continuous rise of the advanced high-power gas turbine thrust-to-weight ratio, by coating high-temperature-resistant and high-thermal-insulation ceramic materials on the surface of parts, the thermal barrier coating technology, which reduces the surface temperature of the parts and prolongs the service life of the parts, has gradually become one of the key technologies in gas turbine manufacturing. The thermal barrier coating of high-pressure turbine components, especially the first-stage moving blade, is constantly designed with new structures and new materials to improve the thermal insulation capacity of the coating and increase the service capacity of the hot end components, and has an extremely important and extensive application prospect in the gas turbine manufacturing industry.

[0003] The thermal barrier coating has been widely used in aeroengines and gas turbines, but unlike aeroengines, the operating cycle of a gas turbine can reach 25,000 hours or even longer, and it is subjected to high-speed centrifugal force, corrosive atmosphere and gas dust erosion for a long time. Early peeling of the thermal barrier coating may occur during application, which can cause the blade to be directly exposed to high-temperature gas, greatly increasing the risk of blade damage. This makes the reliability of the thermal barrier coating used on the gas turbine blade particularly important.

[0004] If the reliability of the thermal barrier coating at different process adjustment stages can be quickly judged under test conditions, the development cycle of the coating technology can be greatly shortened, the development cost can be saved, and the iteration of new thermal barrier coatings can be facilitated. At present, the common method for testing the reliability of the thermal barrier coating on the surface of the gas turbine turbine blade is to perform a thermal shock test on the coated blade or sample, that is, to accelerate the simulation of the start-stop state of the gas turbine by repeatedly heating and cooling the sample, and to evaluate the reliability of the coating by the number of failures of the coating, such as the method provided in GB / T 42259. The applicant has searched a patent with publication number CN 101694432B, which provides a comprehensive evaluation method and device for the reliability of the thermal barrier coating. However, this method does not take into account the erosion effect of dust and particles in the actual gas on the thermal barrier coating, and also does not take into account the difference between the stress state of the coating prepared by using a flat plate sample and the blade, making it difficult to simulate the actual service conditions of the thermal barrier coating and truly evaluate the reliability of the thermal barrier coating. The patent with publication number CN 109446592B provides a method for evaluating the thermal insulation performance and stress level of the thermal barrier coating by a finite element calculation method, which also only considers the influence of the thermal-mechanical field on the coating. Therefore, how to more truly simulate the service environment of the turbine blade under test conditions and establish a reliability evaluation method for the thermal barrier coating on the turbine blade is of great significance to the application of the thermal barrier coating. SUMMARY

[0005] The present application aims to provide a test method for evaluating the reliability of EBPVD coating of turbine blades of gas turbine.

[0006] A test method for evaluating the reliability of EBPVD coating of turbine blades of gas turbine, comprising:

[0007] Obtaining a test blade, the surface of which is coated with an EBPVD thermal barrier coating to be tested;

[0008] Fixing the test blade by a supporting tool;

[0009] Spraying a particle-containing flame jet to the surface of the test blade by a supersonic flame gun to simulate the working condition of gas flushing and particle erosion;

[0010] Observing the failure mode of the thermal barrier coating and recording the test count;

[0011] According to the failure mode and the test count, judging the reliability of the thermal barrier coating.

[0012] Further, the spraying of the particle-containing flame jet to the surface of the test blade by the supersonic flame gun comprises:

[0013] Controlling the supersonic flame gun to move at a uniform speed by an industrial robot;

[0014] Injecting corundum sand particles into the flame jet of the supersonic flame gun to form a high-speed particle-containing flame jet;

[0015] Adjusting the jet angle of the flame jet to make the flame jet nearly perpendicular to the plane of the thermal barrier coating of the surface of the test blade;

[0016] Carrying out erosion test on the thermal barrier coating by the high-speed particle-containing flame jet to simulate the high-temperature high-speed flushing and particle erosion environment under the real gas working condition.

[0017] Further, the fixing of the test blade by the supporting tool comprises:

[0018] Clamping the test blade in the supporting tool;

[0019] Fixing the supporting tool in a chuck or a clamping groove;

[0020] Adjusting the angle of the test blade to make the leading edge area of the test blade face the jet direction of the supersonic flame gun so as to make the leading edge area as the main test area and simulate the main stress part under the gas flushing in the actual working condition.

[0021] Further, the observation of the failure mode of the thermal barrier coating and the recording of the test count comprise:

[0022] Observe whether the thermal barrier coating surface is damaged after each test;

[0023] If the thermal barrier coating is damaged, record the test count at the time of damage and determine the type of failure mode;

[0024] If the thermal barrier coating is not damaged, continue testing until damage occurs, and record the test count at the time of final damage;

[0025] According to the type of failure mode and the test count, classify the failure characteristics of the thermal barrier coating.

[0026] Further, the reliability of the thermal barrier coating is determined according to the failure mode and the test count, comprising:

[0027] The failure mode is divided into short-count spalling and long-count erosion wear;

[0028] If the failure mode is short-count spalling, it is determined that the thermal barrier coating has interface defects and does not meet the reliability requirements;

[0029] If the failure mode is long-count erosion wear, it is determined that the thermal barrier coating meets the reliability requirements;

[0030] The thermal barrier coating that meets the reliability requirements is subjected to repetitive testing to obtain consistent results of the failure mode in multiple tests.

[0031] Further, the failure mode is further divided into short-count point spalling, short-count block spalling, long-count point erosion wear, and long-count strip erosion wear;

[0032] According to the subdivided type of the failure mode, the specific form of the thermal barrier coating damage is determined;

[0033] If the failure mode is short-count point spalling or block spalling, it is determined that the coating adhesion is insufficient;

[0034] If the failure mode is long-count point erosion wear or strip erosion wear, it is determined that the coating performance meets the test requirements.

[0035] Further, the repetitive testing of the thermal barrier coating that meets the reliability requirements comprises:

[0036] Select multiple test blades processed using the same process;

[0037] Repeat the erosion test on each test blade to obtain the failure mode and test count of each test;

[0038] Analyze whether the failure modes of multiple test results are consistent;

[0039] According to the consistency of the failure mode, determine whether the stability of the thermal barrier coating process meets the reliability requirements;

[0040] The test results are summarized for reference for subsequent process optimization.

[0041] Further, the parameters of the supersonic flame spraying corundum sand are as follows: natural gas is used as the fuel gas, the natural gas flow is 155-195 NLPM, the oxygen flow is 230-270 NLPM, the shielding gas flow is 300-370 NLPM, the spraying distance is 200-300 mm, and the powder feeding rate is 1-3 r / min.

[0042] Further, the flame flow and the thermal barrier coating plane spraying angle of the test blade surface are 80°-90°, and the spraying angle of 80°-90° is used to simulate the state of dust impacting the blade in the fuel gas.

[0043] Further, the main component of the corundum sand particles is Al2O3, and a small amount of Fe2O3 and SiO2 impurities are contained.

[0044] The present application has the following beneficial effects:

[0045] (1) The test method of the present application has high-temperature, high-speed fuel gas, and particle scouring, which is closer to the real fuel gas flow state.

[0046] (2) The corundum sand is sprayed by the supersonic flame spraying gun to impact the blade coating area, the process flow is simpler and more efficient, the test period is short, and the judgment standard of reliability evaluation is simple and direct. BRIEF DESCRIPTION OF DRAWINGS

[0047] Figure 1 It is a structure schematic diagram of the evaluation test system of the present application;

[0048] Figure 2 It is a schematic diagram of the short cycle point peeling morphology of the coating reliability test of the present application;

[0049] Figure 3 It is a schematic diagram of the short cycle block peeling morphology of the coating reliability test of the present application;

[0050] Figure 4 It is a schematic diagram of the long cycle point erosion wear morphology of the coating reliability test of the present application;

[0051] Figure 5 It is a schematic diagram of the long cycle strip-shaped erosion wear morphology of the coating reliability test of the present application. DETAILED DESCRIPTION

[0052] The present application will be further described below in combination with the drawings.

[0053] As Figure 1As shown, the test system for evaluating the thermal barrier coating system of the present application comprises a supersonic flame spraying gun 1, corundum sand particles 2, a test blade coated with an EBPVD coating 3, and a support fixture 4 in which the test blade is clamped, the support fixture 4 being fixed in a chuck or a clamping groove, the corundum sand particles 2 being injected into the supersonic flame spraying gun 1 through a carrier gas, the natural gas and oxygen being combusted to generate a supersonic flame jet together with pressurized compressed air to accelerate the corundum sand particles 2 to be sprayed out and impact onto the surface of the test blade 3 for testing.

[0054] The test method for evaluating the reliability of the EBPVD coating of the turbine blade of the gas turbine of the present application comprises:

[0055] (1) obtaining a test blade, the surface of the test blade being coated with an EBPVD thermal barrier coating to be tested; (2) fixing the test blade through a support fixture; (3) spraying a flame jet containing particles onto the surface of the test blade by using a supersonic flame spraying gun to simulate the working condition of gas scouring and particle erosion; (4) observing the failure mode of the thermal barrier coating and recording the test count; and (5) judging the reliability of the thermal barrier coating according to the failure mode and the test count.

[0056] In step (2), the test blade is fixed through the support fixture, comprising: clamping the test blade in the support fixture; fixing the support fixture in a chuck or a clamping groove; and adjusting the angle of the test blade so that the leading edge region of the test blade faces the spraying direction of the supersonic flame spraying gun, so that the leading edge region serves as the main test region and simulates the main stress position of gas scouring under actual working conditions.

[0057] The leading edge coating region is selected because, in actual working conditions, the leading edge of the blade is the main windward side, the gas is divided from the leading edge to the two sides of the blade basin and blade back, and the leading edge and the adjacent position are the main regions subjected to the scouring of dust particles in the gas, and it can often be seen in the disassembly inspection that the transition region from the leading edge to the blade back side is the main region where the coating falls off.

[0058] In step (3), the supersonic flame spraying gun is used to spray a high-speed flame jet containing particles onto the surface of the test blade, comprising: controlling the supersonic flame spraying gun to move uniformly and reciprocally through an industrial robot; injecting corundum sand particles into the flame jet of the supersonic flame spraying gun to form a high-speed flame jet containing particles; adjusting the spraying angle of the flame jet so that the flame jet is nearly perpendicular to the plane of the thermal barrier coating of the test blade; and performing erosion testing on the thermal barrier coating through the high-speed flame jet containing particles to simulate the high-temperature high-speed scouring and particle erosion environment under the real gas working condition.

[0059] The parameters of supersonic flame spraying of corundum sand are: natural gas is used as the fuel gas, the natural gas flow rate is 155~195NLPM, the oxygen flow rate is 230~270NLPM, the shielding gas flow rate is 300~370NLPM, the spraying distance is 200~300mm, the powder feeding rate is 1~3r / min, and the main component of corundum sand particles is Al2O3, and it contains a small amount of impurities such as Fe2O3 and SiO2.

[0060] The oxygen / natural gas flow ratio is about 1.78 to 1.89, which belongs to low-temperature, high-speed, oxygen-poor flame flow, so that the corundum sand particles do not melt excessively and soften;

[0061] Supersonic flame spraying is used because its flame outlet velocity is as high as about 7 times the speed of sound. The high-speed flame flow and particle scouring can quickly present the test results of coating performance and shorten the assessment cycle. A rotary powder feeder is used to ensure that the powder is evenly injected into the flame flow.

[0062] The spray angle between the flame flow and the plane of the thermal barrier coating on the test blade surface is 80° to 90°. The spray angle of 80° to 90° simulates the state of dust in the gas impacting the blade. If the angle is too sharp, it will be more of abrasion rather than erosion. The constant movement speed of the spray gun is 200 to 300 mm / s.

[0063] In steps (4) and (5), the failure morphology of the thermal barrier coating is observed and the test count is recorded, including: observing whether the surface of the thermal barrier coating is damaged after each test; if the thermal barrier coating is damaged, recording the test count at the time of damage and determining the type of failure morphology; if the thermal barrier coating is not damaged, continuing the test until damage occurs, and recording the test count at the final damage; and classifying the failure characteristics of the thermal barrier coating according to the type of failure morphology and the test count.

[0064] The reliability of the thermal barrier coating is judged based on the failure morphology and test counts, including: classifying the failure morphology into two categories: short-count spalling and long-count erosion wear; if the failure morphology is short-count spalling, the thermal barrier coating is judged to have interface defects and does not meet the reliability requirements; if the failure morphology is long-count erosion wear, the thermal barrier coating is judged to meet the reliability requirements; repeat testing is performed on the thermal barrier coating that meets the reliability requirements to obtain consistent failure morphology results from multiple tests.

[0065] Repeatability testing is performed on test blades processed with the same process and showing a long-term erosion wear morphology. The repeatability test should be conducted no less than 3 times to analyze the coating failure morphology and determine whether the processing stability of the test blades meets the reliability test requirements.

[0066] The failure mode is subdivided into short-cycle point peeling, short-cycle block peeling, long-cycle point erosion wear and long-cycle strip erosion wear; according to the subdivided type of the failure mode, the specific form of the thermal barrier coating damage is determined; if the failure mode is short-cycle point peeling or block peeling, it is judged that the coating adhesion is insufficient; if the failure mode is long-cycle point erosion wear or strip erosion wear, it is judged that the coating performance meets the test requirements.

[0067] As Figure 2 Short-cycle point peeling or Figure 3 Short-cycle block peeling, which occurs, belongs to coating damage failure caused by insufficient coating adhesion, and should be fed back to the process development party for process scheme adjustment; if the failure form is long-cycle wear, the coating wear area and the surrounding coating have obvious progressive transition changes, and have typical wear consumption appearance characteristics, such as Figure 3 And Figure 4 Point wear or strip wear, which occurs, belongs to coating characteristics meeting the reliability test requirements.

[0068] The above only describes the preferred embodiments of the present application and is not used to limit the present application, and for those skilled in the art, the present application can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included in the protection scope of the present application.

Claims

1. A test method for evaluating the reliability of EBPVD coating on gas turbine blades, characterized in that: include: Obtaining a test blade, wherein the surface of the test blade is coated with an EBPVD thermal barrier coating to be tested; Fix the test blade by means of a support fixture; A supersonic flame spray gun is used to spray a flame flow containing particles onto the surface of the test blade to simulate the working conditions of gas scouring and particle erosion; Observe the failure morphology of thermal barrier coating and record the test times; The reliability of thermal barrier coatings is judged based on failure morphology and test counts.

2. A test method for evaluating the reliability of EBPVD coatings on gas turbine blades according to claim 1, characterized in that: The method of using a supersonic flame spray gun to spray a flame flow containing particles onto the surface of a test blade comprises: The supersonic flame spray gun is controlled by an industrial manipulator to perform uniform reciprocating motion; injecting corundum sand particles into the flame flow of the supersonic flame spray gun to form a high-speed flame flow containing particles; Adjust the spray angle of the flame so that the flame is nearly perpendicular to the thermal barrier coating plane on the test blade surface; The thermal barrier coating is subjected to an erosion test by a high-speed flame flow containing particles, simulating the high-temperature, high-speed erosion and particle erosion environment under real gas working conditions.

3. A test method for evaluating the reliability of EBPVD coatings on gas turbine blades according to claim 1, characterized in that: Fixing the test blade by the support fixture includes: Clamp the test blade into the support fixture; Fix the supporting tooling in the chuck or slot; The angle of the test blade is adjusted so that the air inlet edge area of ​​the test blade faces the spray direction of the supersonic flame spray gun, so that the air inlet edge area serves as the main test area to simulate the main stress-bearing part of the gas scouring under actual working conditions.

4. A test method for evaluating the reliability of EBPVD coatings on gas turbine blades according to claim 1, characterized in that: The observation of the failure morphology of the thermal barrier coating and recording of the test times include: After each test, observe whether the thermal barrier coating surface is damaged; If the thermal barrier coating is damaged, record the test times at the time of damage and determine the type of failure mode; If the thermal barrier coating is not damaged, continue the test until damage occurs, and record the test count at the final damage; The failure characteristics of thermal barrier coatings are classified according to the type of failure mode and test count.

5. A test method for evaluating the reliability of EBPVD coatings on gas turbine blades according to claim 1, characterized in that: The reliability of the thermal barrier coating is judged based on the failure mode and test count, including: The failure modes are divided into two categories: short-time spalling and long-time erosion wear. If the failure mode is short-count peeling, it is judged that the thermal barrier coating has interface defects and does not meet the reliability requirements; If the failure mode is long-time erosion wear, the thermal barrier coating is judged to meet the reliability requirements; Repeated testing is performed on thermal barrier coatings that meet reliability requirements to obtain consistent failure morphology results across multiple tests.

6. A test method for evaluating the reliability of EBPVD coatings on gas turbine blades according to claim 5, characterized in that: The failure morphology is subdivided into short-time point-like spalling, short-time block-like spalling, long-time point-like erosion wear and long-time strip-like erosion wear; Determine the specific form of thermal barrier coating damage based on the subdivision of failure morphology; If the failure morphology is short-count point-like peeling or block-like peeling, it is judged that the coating adhesion is insufficient; If the failure mode is long-term pitting erosion wear or striping erosion wear, it is judged that the coating performance meets the test requirements.

7. A test method for evaluating the reliability of EBPVD coatings on gas turbine blades according to claim 5, characterized in that: The repeatability test of the thermal barrier coating that meets the reliability requirements includes: Select multiple test blades processed using the same process; Repeat the erosion test on each test blade to obtain the failure mode and test count for each test; Analyze whether the failure modes of multiple test results are consistent; Based on the consistency of the failure modes, determine whether the stability of the thermal barrier coating process meets the reliability requirements; The test results are summarized and used as a reference for subsequent process optimization.

8. A test method for evaluating the reliability of EBPVD coatings on gas turbine blades according to claim 2, characterized in that: The parameters of the supersonic flame spraying of corundum sand are: natural gas is used as the fuel gas, the natural gas flow rate is 155-195NLPM, the oxygen flow rate is 230-270NLPM, the shielding gas flow rate is 300-370NLPM, the spraying distance is 200-300mm, and the powder feeding rate is 1-3r / min.

9. A test method for evaluating the reliability of EBPVD coatings on gas turbine blades according to claim 2, characterized in that: The spraying angle between the flame flow and the plane of the thermal barrier coating on the test blade surface is 80° to 90°, and the spraying angle of 80° to 90° simulates the state in which dust in the combustion gas impacts the blade.

10. A test method for evaluating the reliability of EBPVD coatings on gas turbine blades according to claim 2, characterized in that: The main component of the corundum sand particles is Al2O3, and contains a small amount of Fe2O3 and SiO2 impurities.

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