Method for laser cleaning to remove environmental deposits from a thermal barrier coating surface of an aeroengine

Abstract

The application provides a method for removing environmental deposits on the surface of a thermal barrier coating of an aero-engine by laser cleaning. The thermal barrier coating with CMAS on the surface is placed on the workbench of a pulsed laser system device, and a pulsed laser with a power of 50W-200W is used; 1 / 2-3 / 4 of the thickness of the CMAS layer is removed by laser for the first time, the number of laser cleaning is increased to ensure that the CMAS layer is completely removed, and the thickness of the CMAS layer on the surface of the coating removed by a single laser is not more than 5 microns; after the CMAS layer is completely cleaned, 5-30 microns of the coating is continuously removed. The thickness of the thermal barrier coating on the surface of the blade can basically be maintained at 2 / 3 or more of the original coating thickness. The thermal barrier coating on the surface of the blade after laser cleaning is basically undamaged, can continue to exist on the surface of the engine blade to play its original effect, and the aero-engine blade can still be put into actual application. The application can be used for removing CMAS on the surface of the thermal barrier coating of the aero-engine. The operation is simple, the effect is obvious, and the cost is low.

Description

Technical Field

[0001] The present invention belongs to the technical field of surface processing, and specifically refers to a method for removing environmental deposits on the surface of an aircraft engine thermal barrier coating by laser cleaning; laser surface treatment is used to remove environmental deposits CMAS (calcium magnesium aluminum silicate) remaining on the surface of the aircraft engine thermal barrier coating, wherein the thermal barrier coating includes a ceramic coating, a metal bonding layer and a substrate. Background Art

[0002] Modern aircraft engines operate at higher temperatures and in harsher service environments. As one of the key core technologies for aircraft engine turbine blades, thermal barrier coatings (TBCs) can significantly reduce the surface temperature of engine blades, thereby improving engine operating temperature and efficiency.

[0003] Current aircraft engine thermal barrier coatings (TBCs) typically consist of a multilayer structure consisting of a ceramic coating, a metallic bond layer, and a substrate. The most widely used ceramic coating is YSZ (7-8 wt% Y2O3 partially stabilized with ZrO2), typically produced using atmospheric plasma spraying (APS), electron beam physical vapor deposition (EB-PVD), and plasma spray physical vapor deposition (PS-PVD). The metallic bond layer, serving as the connecting layer between the substrate and the ceramic layer, is typically made of MCrAlY (M is Ni, Co, or Ni+Co) to enhance the bonding strength between the ceramic coating and the substrate and provide excellent resistance to oxidative corrosion. As aircraft engine operating environments become increasingly harsh and operating temperatures rise, the challenges facing TBCs have garnered significant attention in recent years. Among these, the corrosion of thermal barrier coatings by CMAS is particularly concerning. Calcium magnesium aluminum silicate (CMAS), primarily composed of CaO, MgO, Al2O3, and SiO2, is a major cause of aircraft engine component failure. When the temperature is lower than 1250℃, CMAS cannot become a molten state at a lower temperature and will not penetrate into the coating along the pores and cracks inside the coating, causing coating failure. Instead, it will be deposited on the surface of the YSZ thermal barrier coating in the form of solid CMAS, causing CMAS adhesion on the coating surface, which is not conducive to the subsequent normal operation of the aircraft engine turbine blades.

[0004] The service temperatures of today's new generation of advanced engine turbine blades have increased significantly, raising the bar for thermal barrier coatings (TBCs) in aircraft engines. YSZ TBCs can experience phase transitions and sintering at temperatures above 1200°C. Furthermore, molten CMAS can penetrate through pores and cracks within the coating, causing coating failure. This makes it difficult to meet the demands of the next generation of high-thrust-to-weight ratio aircraft engines. Consequently, a series of new ultra-high-temperature, high-insulation TBCs have emerged.

[0005] While new ultra-high-temperature, high-insulation TBCs, such as rare earth zirconates and rare earth phosphates, can rapidly react with molten CMAS to form a crystalline phase, promoting crystallization of the CMAS melt and forming a continuous, dense reaction layer at the interface between the two, effectively inhibiting continued CMAS infiltration, CMAS that cannot penetrate the coating will still adhere to the surface of the thermal barrier coating. Solid CMAS adhering to the coating surface increases the weight of the engine blade, significantly reducing the thrust-to-weight ratio of the aircraft engine. Solid CMAS adhering to the coating surface can also clog the blade cooling channels, causing localized overburning and subsequently further corroding the coating, negatively impacting the service life of the engine blade. Therefore, to extend the service life of both thermal barrier coatings and aircraft engines, and to improve their performance, it is essential to develop a new CMAS cleaning method.

[0006] To date, researchers have proposed numerous approaches to protect thermal barrier coatings from CMAS corrosion, including using a surface protective layer to directly block the penetration of molten CMAS by leveraging its continuous and dense properties, modifying the YSZ coating material to induce surface CMAS crystallization into impermeable crystalline products, developing novel ultra-high-temperature thermal barrier coatings (TBCs), and optimizing the structural design of TBCs for CMAS corrosion resistance. However, these approaches only block the penetration and corrosion of molten CMAS into the thermal barrier coating and fail to effectively remove CMAS adhering to the thermal barrier coating surface, which can subsequently cause further corrosion. Previous studies have shown that laser modification of YSZ coatings can densify the coating, ultimately achieving excellent CMAS corrosion resistance. Therefore, lasers hold great potential for CMAS corrosion protection. However, an effective method for removing CMAS adhering to the surface of thermal barrier coatings has yet to be discovered. This patent proposes a simple and cost-effective laser shock wave cleaning method for CMAS, in which the laser is incident parallel to the substrate surface, without contacting the substrate. After laser output, the air at the focal point ionizes, generating a shock wave that rapidly expands in a spherical shape. When the lateral torque of the shock wave acting on the CMAS particles exceeds the longitudinal torque and the particle adhesion force, the CMAS particles roll away. After cleaning, the CMAS on the sample surface is largely removed, and the thermal barrier coating continues to function effectively on the engine blade. Summary of the Invention

[0007] The present invention provides a method for laser cleaning and removing environmental deposits from the surface of aircraft engine thermal barrier coatings. By utilizing the high intensity, high energy density, good focusing, and strong directionality of lasers, the air at the laser focus undergoes ionization, generating shock waves that overcome the binding forces between CMAS and the thermal barrier coating surface, thereby completely detaching the CMAS from the coating surface and achieving surface cleaning. Optimized laser parameters are used to clean the CMAS from the thermal barrier coating surface. The initial laser treatment removes 1 / 2-3 / 4 of the CMAS layer thickness. Subsequent laser cleaning cycles are repeated to ensure complete removal of the CMAS layer. Subsequent single laser cleaning cycles ensure no more than 5 μm of CMAS layer thickness is removed from the coating surface. After the CMAS layer is completely cleaned, further removal of 5-30 μm of coating is performed. After laser cleaning, the thermal barrier coating on the blade surface is essentially undamaged and can continue to function effectively on the engine blade surface. Its thickness can be maintained at or above 2 / 3 of the original coating thickness. After the cleaned surface, the aircraft engine blade can continue to be used in practical applications. The present invention can be used to effectively remove environmental deposits CMAS from the thermal barrier coating surface of aircraft engine turbine blades. The laser cleaning method for environmental deposits on the surface of thermal barrier coatings is simple to operate, has obvious effects, and is low in cost.

[0008] In order to achieve the above object, the present invention adopts the following technical solutions:

[0009] A method for laser cleaning and removing environmental deposits on the surface of an aircraft engine thermal barrier coating comprises placing a thermal barrier coating with CMAS attached to its surface on a workbench of a pulsed laser system device, using a pulsed laser with a power of 50W-200W; initially, the laser is used to remove 1 / 2-3 / 4 of the thickness of the CMAS layer, and subsequently, the laser cleaning times are increased to ensure complete removal of the CMAS layer, with the subsequent single removal of the CMAS layer thickness not exceeding 5μm. After the CMAS layer is completely cleaned, another 5-30μm of the coating is removed.

[0010] The angle between the laser beam and the surface of the thermal barrier coating sample is 5-10 degrees.

[0011] During the laser cleaning process, the laser system parameters are set to pulse width 0.5-1.5 ms, frequency 20-40 Hz, current 10-30 A, scanning speed 5-15 mm / s, and beam length 100-200 mm;

[0012] The thickness of the thermal barrier coating after laser cleaning can basically be maintained at 2 / 3 or more of the original coating thickness.

[0013] After laser cleaning, the thermal barrier coating on the blade surface is basically undamaged and can continue to exist on the surface of the engine blade to play its original function, and the aircraft engine blade can still continue to be put into practical use.

[0014] Laser cleaning method is used to remove environmental deposits CMAS on the surface of thermal barrier coating of aero-engine turbine blades.

[0015] Beneficial effects of the present invention:

[0016] This invention utilizes the high intensity, high energy density, good focusing, and strong directionality of lasers to ionize the air at the laser's focal point, generating shock waves that overcome the binding forces between CMAS and the thermal barrier coating surface, essentially completely separating the CMAS from the coating surface. This effectively cleans the surface, preventing solid CMAS from clogging blade cooling channels, increasing blade weight, and further corroding the blade during subsequent service. This significantly improves the thrust-to-weight ratio of aircraft engines and extends the service life of engine blades. Optimized laser parameters are used to clean CMAS from the thermal barrier coating surface. The initial laser treatment removes 1 / 2-3 / 4 of the CMAS layer thickness. Subsequent laser cleaning cycles are repeated to ensure complete CMAS removal. Subsequent single laser treatments remove no more than 5 μm of CMAS from the coating surface. After the CMAS layer is completely cleaned, further 5-30 μm of coating is removed. The thickness of the thermal barrier coating on the blade surface is essentially maintained at or above 2 / 3 of the original coating thickness. After laser cleaning, the thermal barrier coating on the blade surface remains largely intact, allowing it to continue to function properly, allowing the aeroengine blade to continue to be used in practical applications. This method can be used to remove CMAS from aeroengine thermal barrier coatings. It offers simple operation, significant results, and low cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 Diagram of the laser system structure for laser cleaning to remove environmental deposits from the surface of aircraft engine thermal barrier coatings.

[0018] Figure 2 Schematic diagram of the surface macroscopic morphology of the thermal barrier coating sample with CMAS in Example 1 of the present invention.

[0019] Figure 3 This is a cross-sectional microstructure diagram of a thermal barrier coating sample with CMAS in Example 1 of the present invention.

[0020] Figure 4 Schematic diagram of the surface macroscopic morphology of the thermal barrier coating sample after laser cleaning in Example 1 of the present invention.

[0021] Figure 5 This is a cross-sectional microstructure diagram of the thermal barrier coating sample after laser cleaning in Example 1 of the present invention. DETAILED DESCRIPTION

[0022] In order to make the purpose, technical solutions and advantages of the present invention clearer and more specific, the present invention is further described below through specific embodiments.

[0023] A method for removing environmental deposits on the surface of an aircraft engine thermal barrier coating by laser cleaning; comprising the following steps:

[0024] 1) Select a thermal barrier coating sample with environmental deposits (CMAS) on the surface, place the sample on the workbench of the pulsed laser system and fix its position;

[0025] 2) Use a pulsed laser with a power of 50W-200W to perform laser cleaning on the environmental deposits CMAS on the surface of the thermal barrier coating;

[0026] 3) Laser cleaning parameters are: pulse width 0.5-1.5ms, frequency 20-40Hz, current 10-30A, scan speed 5-15mm / s, and beam length 100-200mm. During the laser cleaning process, the laser beam is positioned at an angle of 5-10° to the thermal barrier coating surface, removing CMAS deposits layer by layer.

[0027] 4) The first laser removes 1 / 2-3 / 4 of the thickness of the CMAS layer, and then increases the number of laser cleaning times to ensure that the CMAS layer is completely removed. The thickness of the CMAS layer on the coating surface removed in a single subsequent time does not exceed 5μm. After the CMAS layer is completely cleaned, continue to remove 5-30μm of the coating.

[0028] Example 1

[0029] 1. A yttria partially stabilized zirconia (YSZ) thermal barrier coating sample with environmental deposits (CMAS) on the surface was selected. The thickness of the CMAS layer on the surface was about 20 μm. The thermal barrier coating on the surface of the sample was prepared by atmospheric plasma spraying with a thickness of 150 μm.

[0030] 2. Place the YSZ thermal barrier coating sample with CMAS attached to the surface on the workbench of the pulse laser system and fix its position. Figure 1 Diagram of the laser system structure for laser cleaning to remove environmental deposits from the surface of aircraft engine thermal barrier coatings.

[0031] 3. The CMAS on the surface of the YSZ thermal barrier coating specimen was laser cleaned using a Nd:YAG solid-state pulsed laser with a rated power of 200W. During laser cleaning, the angle between the laser beam and the thermal barrier coating surface of the specimen was 5-10°, and the laser focus was controlled to fall on the surface of the CMAS as much as possible. The laser system parameters used included a pulse width of 0.5ms, a frequency of 20Hz, a current of 20A, a scanning speed of 5mm / s, and a beam length of 140mm. The thermal barrier coating on the specimen surface was cleaned three times in succession. The first laser cleaning removed a 12μm thick CMAS layer. In subsequent cleaning processes, the thickness of the laser cleaning was removed each time by 5μm. After the CMAS layer was completely cleaned, the laser was used to remove another 30μm of coating.

[0032] Schematic diagram of the surface macromorphology of the thermal barrier coating sample with CMAS attached Figure 2 As shown in the figure, the cross-sectional microstructure of the thermal barrier coating sample with CMAS is observed. Figure 3 shown.

[0033] Schematic diagram of the surface macromorphology of the thermal barrier coating sample after laser cleaning Figure 4 As shown in the figure, the cross-sectional microstructure of the thermal barrier coating sample after laser cleaning is shown in the figure. Figure 5 shown.

[0034] contrast Figure 2 and Figure 4 There is a large amount of CMAS attached to the surface of the original YSZ spray coating, and the surface color of the substrate is brown. After three laser cleaning treatments, the brown area on the surface of the substrate has basically disappeared, and it has begun to turn gray and dark.

[0035] contrast Figure 3 and Figure 5 There is a large amount of CMAS deposited on the surface of the original YSZ spray coating. The CMAS on the surface of the sample after laser cleaning has been completely removed, and the YSZ thermal barrier coating has been retained relatively evenly and completely, with the thickness basically maintained at the original level. This shows that the pulsed laser has an excellent cleaning effect on the CMAS on the surface of the thermal barrier coating, and protects the YSZ coating from damage to the greatest extent. After testing, the retained YSZ coating can still play its original role on the blade surface, which shows that this laser shock wave method of cleaning CMAS is effective.

[0036] Example 2

[0037] 1. A YSZ thermal barrier coating sample with environmental deposits (CMAS) on the surface was selected. The thickness of the CMAS layer on the surface was about 30 μm. The thermal barrier coating on the surface of the sample was prepared by electron beam-physical vapor deposition method with a thickness of 110 μm.

[0038] 2. Place the thermal barrier coating sample with CMAS attached to the surface on the workbench of the pulse laser system device and fix its position.

[0039] 3. The CMAS on the surface of the YSZ thermal barrier coating specimen was laser cleaned using a Nd:YAG solid-state pulsed laser with a rated power of 200W. During laser cleaning, the angle between the laser beam and the thermal barrier coating surface of the specimen was 5-10°, and the laser focus was controlled to fall on the surface of the CMAS as much as possible. The laser system parameters used included a pulse width of 1.5ms, a frequency of 40Hz, a current of 20A, a scanning speed of 5mm / s, and a beam length of 200mm. The thermal barrier coating on the specimen surface was cleaned four times in a row. The thickness of the CMAS layer removed by the first laser cleaning was 20μm. In the subsequent cleaning processes, the thickness of the laser cleaning was removed by each laser cleaning was 4μm. After the CMAS layer was completely cleaned, the laser was used to remove another 15μm of coating.

[0040] Increasing the laser pulse width and power increases the heat input. After laser cleaning, the brown areas on the sample surface were significantly reduced. No traces of CMAS elements such as Ca and Si were detected on the thermal barrier coating surface, and no CMAS corrosion products were observed in most areas of the thermal barrier coating surface. This indicates that the laser power is higher at a pulse width of 0.6ms. Higher laser power generates greater laser pulse energy, which intensifies the ionization of the air near the CMAS particles. Even at longer laser beam lengths, the bonding between the CMAS and the thermal barrier coating is sufficiently strong to be effectively overcome by the shock wave generated by the ionization. After cleaning, the coating thickness remains around 95μm, and the YSZ coating is largely undamaged. The remaining YSZ coating was tested and still functioned properly on the blade surface, demonstrating the remarkable effectiveness of this laser shockwave-based CMAS cleaning method.

[0041] Example 3

[0042] 1. A gadolinium phosphate (GdPO4) thermal barrier coating sample with environmental deposits (CMAS) on the surface was selected. The thickness of the CMAS layer on the surface was about 35 μm. The thermal barrier coating on the surface of the sample was prepared by atmospheric plasma spraying with a thickness of 140 μm.

[0043] 2. Place the GdPO4 thermal barrier coating sample with CMAS attached to the surface on the workbench of the pulse laser system device and fix its position.

[0044] 3. The CMAS on the surface of the GdPO4 thermal barrier coating specimen was laser cleaned using a Nd:YAG solid-state pulsed laser with a rated power of 200W. During laser cleaning, the angle between the laser beam and the thermal barrier coating surface of the specimen was 5-10°, and the laser focus was controlled to fall on the surface of the CMAS as much as possible. The laser system parameters used included a pulse width of 0.5ms, a frequency of 30Hz, a current of 10A, a scanning speed of 5mm / s, and a beam length of 100mm. The thermal barrier coating on the specimen surface was cleaned four times in succession. The thickness of the CMAS layer removed by the first laser cleaning was 25μm. In the subsequent cleaning processes, the thickness of the CMAS layer removed by each laser cleaning was 4μm. After the CMAS layer was completely cleaned, the laser was used to remove another 25μm of coating.

[0045] As the laser beam length decreases, the distance between the sample and the laser focus decreases, and the smaller spot size increases the power density, which in turn increases the laser pulse energy received by the coating surface. Because the sample is close to the laser focus, parts of the GdPO4 coating surface appear gray-black after laser cleaning, indicating a more pronounced laser cleaning effect. The CMAS layer and corrosion reaction layer on the surface of the GdPO4 coating completely disappear, leaving only the composition of the GdPO4 coating detectable, with only a slight decrease in the thickness of the GdPO4 coating. At the same time, the number of reticular cracks and tiny voids within the coating increases. These defects help increase the coating's strain tolerance, improve thermal shock resistance, and extend thermal cycling life.

[0046] Example 4

[0047] 1. A gadolinium zirconate (Gd2Zr2O7) thermal barrier coating sample with environmental deposits (CMAS) on the surface was selected. The thickness of the CMAS layer on the surface was about 25μm. The thermal barrier coating on the surface of the sample was prepared by plasma spraying-physical vapor deposition method with a thickness of 135μm.

[0048] 2. Place the Gd2Zr2O7 thermal barrier coating sample with CMAS attached to its surface on the workbench of the pulsed laser system and fix its position.

[0049] 3. The CMAS on the surface of the Gd2Zr2O7 thermal barrier coating specimen was laser cleaned using a Nd:YAG solid-state pulsed laser with a rated power of 200W. During laser cleaning, the specimen was placed vertically with the specimen parallel to the laser beam. The laser system parameters used included a pulse width of 0.6ms, a frequency of 40Hz, a current of 30A, a scanning speed of 5mm / s, and a beam length of 130mm. The thermal barrier coating on the specimen surface was cleaned five times in succession. The thickness of the CMAS layer removed by the first laser cleaning was 15μm. In the subsequent cleaning processes, the thickness of the CMAS layer removed by each laser cleaning was 3μm. After the CMAS layer was completely cleaned, the laser was used to remove another 30μm of coating.

[0050] When the specimen is positioned vertically, controlling the distance between the sample and the laser beam is extremely difficult. Too far will result in suboptimal cleaning, while too close can easily damage the coating and substrate. Due to the vertical orientation of the specimen, scanning electron microscopy (SEM) microscopic observation of the cross-section revealed that the coating thickness was reduced to approximately four-fifths of its original thickness after laser cleaning. Energy dispersive spectroscopic analysis revealed no significant presence of elements such as Al and Ca on the coating surface, indicating complete removal of the CMAS. The surface became smooth and dense, with a few vertical cracks present. In some areas, the residual coating after cleaning was thick (approximately 105-115 μm), but some CMAS was observed to penetrate deep into the coating (maximum depth of approximately 30 μm). This is due to the difficulty in precisely controlling the distance between the sample and the laser beam during laser cleaning. A large distance between the laser and the sample reduces the impact force generated by the ionization process. Due to the high melting point and poor fluidity of CMAS, the impact force is insufficient to rapidly remove the CMAS, causing it to melt deeply into the coating under the thermal action of the laser.

[0051] Example 5

[0052] 1. A yttrium aluminum garnet (YAG) thermal barrier coating sample with environmental deposits (CMAS) on the surface was selected. The thickness of the CMAS layer on the surface was about 32 μm. The thermal barrier coating on the surface of the sample was prepared by plasma spraying-physical vapor deposition method with a thickness of 140 μm.

[0053] 2. Place the YAG thermal barrier coating sample with CMAS attached to the surface on the workbench of the pulse laser system device and fix its position.

[0054] 3. Laser cleaning of the CMAS layer on the surface of a yttrium aluminum garnet (YAG) thermal barrier coating (TBC) specimen was performed using a Nd:YAG solid-state pulsed laser with a rated power of 200W. During laser cleaning, the laser beam was positioned at an angle of 5-10° to the TBC surface, and the laser focus was controlled to focus on the CMAS surface as closely as possible. The laser system parameters used a pulse width of 0.5ms, a frequency of 40Hz, a current of 20A, a scanning speed of 15mm / s, and a beam length of 140mm. The TBC layer on the specimen was cleaned four times in succession. The first laser cleaning removed a 23μm thick CMAS layer, and each subsequent laser cleaning removed 3μm of the layer. After the CMAS layer was completely cleaned, the laser was used to remove another 26μm of the coating.

[0055] As the laser beam's scanning speed increases and the heat input decreases, the effectiveness of CMAS removal from the YAG thermal barrier coating surface decreases. After laser cleaning, the majority of the CMAS deposited on the YAG thermal barrier coating surface has disappeared, but a small amount of residual CMAS corrosion remains in certain areas. This is due to the laser melting the CMAS and cladding it onto the YAG coating surface. With increased cleaning cycles, the remaining CMAS on the coating surface is completely removed. Testing of the remaining YAG coating reveals that it still performs its original function on the blade surface, demonstrating the effectiveness of this laser shockwave-based CMAS cleaning method.

[0056] Example 6

[0057] 1. A YbTaO4 thermal barrier coating sample with environmental deposits (CMAS) on the surface was selected. The thickness of the CMAS layer on the surface was about 34 μm. The thermal barrier coating on the surface of the sample was prepared by plasma spraying-physical vapor deposition method with a thickness of 145 μm.

[0058] 2. Place the YbTaO4 thermal barrier coating sample with CMAS attached to the surface on the workbench of the pulse laser system device and fix its position.

[0059] 3. The CMAS on the surface of the YbTaO4 thermal barrier coating specimen was laser cleaned using a Nd:YAG solid-state pulsed laser with a rated power of 200W. During laser cleaning, the angle between the laser beam and the thermal barrier coating surface of the specimen was 5-10°, and the laser focus was controlled to fall on the surface of the CMAS as much as possible. The laser system parameters used included a pulse width of 0.5ms, a frequency of 40Hz, a current of 20A, a scanning speed of 10mm / s, and a beam length of 140mm. The thermal barrier coating on the specimen surface was cleaned six times in a row. The thickness of the CMAS layer removed by the first laser cleaning was 20μm. In subsequent cleaning processes, the thickness of the laser cleaning was removed by each laser cleaning step was 3μm. After the CMAS layer was completely cleaned, the laser was used to remove another 27μm of coating.

[0060] With increasing laser cleaning cycles, the thermal barrier coating surface was more thoroughly cleaned. After laser cleaning, most areas of the YbTaO4 thermal barrier coating surface appeared gray-black, demonstrating a significant laser cleaning effect. The CMAS layer on the YbTaO4 thermal barrier coating surface completely disappeared, leaving only the YbTaO4 coating composition detectable, with no CMAS corrosion products such as Ca2Ta2O7 present. The YbTaO4 coating thickness decreased slightly, but remained approximately 5 / 6 of the original thickness. Testing revealed that the remaining YbTaO4 coating still performed its original function on the blade surface, demonstrating the effectiveness of this laser shockwave-based CMAS cleaning method.

[0061] Example 7

[0062] 1. A Gd2Zr2O7 thermal barrier coating sample with environmental deposits (CMAS) on the surface was selected. The thickness of the CMAS layer on the surface was about 30 μm. The thermal barrier coating on the surface of the sample was prepared by electron beam-physical vapor deposition method with a thickness of 105 μm.

[0063] 2. Place the Gd2Zr2O7 thermal barrier coating sample with CMAS attached to its surface on the workbench of the pulsed laser system and fix its position.

[0064] 3. Laser cleaning of the CMAS on the surface of the Gd2Zr2O7 thermal barrier coating specimen was performed using a Nd:YAG solid-state pulsed laser with a rated power of 200W. During laser cleaning, the laser beam was kept at an angle of 5-10° to the thermal barrier coating surface of the specimen, and the laser focus was controlled to fall on the surface of the CMAS as much as possible. The laser system parameters used included a pulse width of 1ms, a frequency of 25Hz, a current of 15A, a scanning speed of 12mm / s, and a beam length of 160mm. The thermal barrier coating on the specimen surface was cleaned four times in a row. The thickness of the CMAS layer removed by the first laser cleaning was 20μm. In subsequent cleaning processes, the thickness of the laser cleaning was removed by each laser cleaning step was 4μm. After the CMAS layer was completely cleaned, the laser was used to remove another 15μm of coating.

[0065] After grinding and polishing, scanning electron microscopy (SEM) was used to examine the cross-section of the laser-cleaned Gd2Zr2O7 thermal barrier coating. The CMAS layer and reaction layer on the surface of the Gd2Zr2O7 thermal barrier coating were completely eliminated, and the coating thickness was slightly reduced to approximately 15 μm, remaining approximately 6 / 7 of the original coating thickness. XRD and energy spectrum analysis confirmed that only the Gd2Zr2O7 coating components were detectable, with no CMAS components such as Ca, Mg, or Si present. The reaction layer phases, including fluorite and apatite, were completely eliminated. The remaining thermal barrier coating was tested and continued to function effectively on the blade surface, demonstrating the effectiveness of this laser shockwave-based CMAS removal method.

[0066] Example 8

[0067] 1. A GdPO4 thermal barrier coating sample with environmental deposits (CMAS) on the surface was selected. The thickness of the CMAS layer on the surface was about 28 μm. The thermal barrier coating on the surface of the sample was prepared by plasma spraying-physical vapor deposition method with a thickness of 150 μm.

[0068] 2. Place the GdPO4 thermal barrier coating sample with CMAS attached to the surface on the workbench of the pulse laser system device and fix its position.

[0069] 3. The CMAS on the surface of the GdPO4 thermal barrier coating sample was laser cleaned using a Nd:YAG solid-state pulsed laser with a rated power of 200W. During laser cleaning, the angle between the laser beam and the thermal barrier coating surface of the sample was 5-10°, and the laser focus was controlled to fall on the surface of the CMAS as much as possible. The parameters used in the laser system included a pulse width of 0.8ms, a frequency of 25Hz, a current of 20A, a scanning speed of 9mm / s, and a beam length of 150mm. The thermal barrier coating on the surface of the specimen was cleaned four times in a row. The thickness of the CMAS layer removed by the first laser cleaning was 17μm. In the subsequent cleaning processes, the thickness of the laser cleaning was removed by each laser cleaning was 4μm. After the CMAS layer was completely cleaned, the laser was used to remove another 25μm of coating.

[0070] After laser cleaning, the macroscopic surface morphology of the GdPO4 coating was observed, revealing a gray-black appearance in some areas. After grinding and polishing, scanning electron microscopy (SEM) was used to examine the cross-section of the laser-cleaned GdPO4 thermal barrier coating. The CMAS layer and reaction layer on the surface of the GdPO4 thermal barrier coating were completely eliminated, and the GdPO4 coating thickness was slightly reduced to approximately 25 μm, remaining approximately 5 / 6 of the original coating thickness. XRD and energy spectrum analysis confirmed that only coating components such as Gd and P were detectable, with no CMAS components such as Ca, Mg, and Si present. No reaction layer phases, such as apatite or anorthite, were present. The remaining thermal barrier coating was tested and continued to function effectively on the blade surface, demonstrating the effectiveness of this laser shock wave-based CMAS cleaning method.

[0071] Example 9

[0072] 1. A gadolinium tantalate (GdTaO4) thermal barrier coating sample with environmental deposits (CMAS) on the surface was selected. The thickness of the CMAS layer on the surface was about 33μm. The thermal barrier coating on the surface of the sample was prepared by atmospheric plasma spraying and had a thickness of 142μm.

[0073] 2. Place the GdTaO4 coating sample with CMAS attached to its surface on the workbench of the pulse laser system device and fix its position.

[0074] 3. The CMAS on the surface of the GdTaO4 coating sample was laser cleaned using a Nd:YAG solid-state pulsed laser with a rated power of 200W. During laser cleaning, the angle between the laser beam and the thermal barrier coating surface of the sample was 5-10°, and the laser focus was controlled to fall on the surface of the CMAS as much as possible. The laser system parameters used included a pulse width of 1.4ms, a frequency of 20Hz, a current of 25A, a scanning speed of 13mm / s, and a beam length of 180mm. The thermal barrier coating on the specimen surface was cleaned four times in a row. The thickness of the CMAS layer removed by the first laser cleaning was 21μm. In the subsequent cleaning processes, the thickness of the laser cleaning was removed by each laser cleaning was 4μm. After the CMAS layer was completely cleaned, the laser was used to remove another 29μm of coating.

[0075] After laser cleaning of the GdTaO4 coating sample, its macroscopic surface morphology was observed, revealing a gray-black appearance in some areas. After grinding and polishing, scanning electron microscopy (SEM) was used to examine the cross-section of the laser-cleaned GdTaO4 coating. The CMAS layer and the reaction layer on the thermal barrier coating surface were completely eliminated, and the coating thickness was slightly reduced to approximately 29 μm, remaining approximately 4 / 5 of the original coating thickness. XRD and energy spectrum analysis confirmed that only coating components such as Ta and Gd were detectable, with no CMAS components such as Ca, Mg, or Si present. Furthermore, the Ca2Ta2O7 phase, a component of the reaction layer, had completely disappeared. The remaining thermal barrier coating was tested and continued to function effectively on the blade surface, demonstrating the effectiveness of this laser shockwave-based CMAS cleaning method.

[0076] Example 10

[0077] 1. A 48 mol% yttria-stabilized zirconia (48YSZ) thermal barrier coating sample with environmental deposits (CMAS) on the surface was selected. The thickness of the surface CMAS layer was about 26 μm. The thermal barrier coating on the surface of the sample was prepared by electron beam-physical vapor deposition method with a thickness of 100 μm.

[0078] 2. Place the 48 mol % yttria-stabilized zirconia coating sample with CMAS attached to the surface on a workbench of a pulsed laser system and fix its position.

[0079] 3. The CMAS on the surface of a 48 mol% yttria-stabilized zirconia coating specimen was laser cleaned using a Nd:YAG solid-state pulsed laser with a rated power of 200 W. During laser cleaning, the laser beam was positioned at an angle of 5-10° to the thermal barrier coating surface of the specimen, and the laser focus was controlled to fall on the surface of the CMAS as much as possible. The laser system parameters used included a pulse width of 1.1 ms, a frequency of 30 Hz, a current of 20 A, a scan speed of 10 mm / s, and a beam length of 120 mm. The thermal barrier coating on the specimen surface was cleaned five times in succession. The thickness of the CMAS layer removed during the first laser cleaning was 16 μm. In subsequent cleaning processes, the thickness of the CMAS layer removed during each laser cleaning was 3 μm. After the CMAS layer was completely cleaned, the laser was used to remove another 17 μm of coating.

[0080] After laser cleaning of a 48 mol% yttria-stabilized zirconia coating, the macroscopic surface morphology was observed, revealing a gray-black appearance in some areas. After grinding and polishing, scanning electron microscopy (SEM) was used to examine the cross-section of the laser-cleaned coating. The CMAS layer and reaction layer on the thermal barrier coating surface had completely disappeared, and the coating thickness had slightly decreased to approximately 17 μm, remaining approximately four-fifths of the original coating thickness. XRD and energy spectrum analysis confirmed that only coating components such as Zr and Y were detectable, with no CMAS components such as Ca, Mg, and Si present. Corrosion products, including spherical m-ZrO₂ particles, had completely disappeared. The remaining thermal barrier coating remained functional on the blade surface, demonstrating the effectiveness of this laser shockwave-based CMAS cleaning method.

[0081] The technical solutions disclosed and proposed by the present invention can be implemented by those skilled in the art by drawing on the content of this document and appropriately changing the conditions, routes, and other aspects. Although the methods and preparation techniques of the present invention have been described through preferred embodiments, it is obvious that those skilled in the art can modify or recombine the methods and technical routes described herein without departing from the content, spirit, and scope of the present invention to achieve the ultimate preparation technology. It is particularly important to point out that all similar substitutions and modifications that are obvious to those skilled in the art are considered to be included in the spirit, scope, and content of the present invention.

Claims

1. A method for laser cleaning and removing environmental deposits on the surface of aero-engine thermal barrier coating, characterized by: A thermal barrier coating with CMAS attached to its surface is placed on a workbench of a pulsed laser system device, and the pulsed laser power used is 50W-200W; the laser is used to remove 1 / 2-3 / 4 of the thickness of the CMAS layer for the first time, and the number of laser cleanings is subsequently increased to ensure that the CMAS layer is completely removed, and the thickness of the CMAS layer on the coating surface removed in a single subsequent time does not exceed 5μm. After the CMAS layer is completely cleaned, 5-30μm of the coating is continued to be removed; the angle between the laser beam and the surface of the thermal barrier coating sample is 5-10°; the laser system parameters are set to a pulse width of 0.5-1.5ms, a frequency of 20-40Hz, a current of 10-30A, a scanning speed of 5-15mm / s, and a beam length of 100-200mm.

2. According to the method of claim 1, the thickness of the thermal barrier coating after laser cleaning can be basically maintained at 2 / 3 or more of the original coating thickness.

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