Thermal barrier coating of complex molded surface and multi-hole flame tube and spraying method of thermal barrier coating

Abstract

The invention relates to a thermal barrier coating of a complex molded surface and a multi-hole flame tube and a spraying method of the thermal barrier coating. The spraying method comprises the steps that the complex molded surface and the multi-hole flame tube are provided; shielding the second opening, and sequentially carrying out first spraying, second spraying and third spraying on the inner walls of the first section, the second section and the third section of the barrel; the edge of the first open hole is shielded, fourth spraying is conducted on the inner wall of the first open hole, a metal bonding layer is formed, and the moving speeds of the spraying guns are different; shielding the second opening, and sequentially performing fifth, sixth and seventh spraying on the surfaces of the metal bonding layers of the first, second and third sections of barrels; and the edge of the first hole is shielded, eighth spraying is conducted on the surface of the metal bonding layer of the first hole, a ceramic surface layer is formed, the thermal barrier coating is obtained, and the moving speeds of the spraying guns are different. The thermal barrier coating is sprayed by combining supersonic flame spraying and atmospheric plasma spraying with segmented spraying, the overall performance is excellent, and the thermal shock resistance and stripping resistance in the using process are effectively improved.

Description

Technical Field

[0001] This invention relates to the technical field of thermal barrier coating spraying methods, and more particularly to a thermal barrier coating for a complex-shaped and multi-aperture flame tube and its spraying method. Background Technology

[0002] As the core hot-end component of an aero-engine combustion chamber, the flame tube is the direct load-bearing space for the combustion reaction of combustion gases, and its working environment is extremely harsh. During normal engine operation, the inner wall of the flame tube must continuously withstand the scouring of high-temperature combustion gases exceeding 1000℃, with peak temperatures reaching 1600℃~1800℃. Simultaneously, it must cope with the periodic thermal shocks caused by combustion gas pulsations, the erosion from high-speed airflow, and the corrosive effects of combustion products. These extreme conditions place almost stringent requirements on the high-temperature strength, oxidation resistance, and thermal fatigue resistance of the flame tube substrate material. Without protective measures, failures such as high-temperature creep, oxidation ablation, or thermal fatigue cracking are highly likely to occur, severely affecting the reliability and service life of the engine. Therefore, preparing high-performance thermal barrier coatings (TBCs) on the surface of high-temperature alloy substrates has become a core technical means to improve the temperature resistance limit of the flame tube and extend its service life.

[0003] A typical double-layer thermal barrier coating system usually adopts a composite structure of "metal bonding layer + ceramic insulation layer", which work together to achieve excellent high-temperature protection. The metal bonding layer is mainly prepared by atmospheric plasma spraying (APS) process, and the materials are mostly nickel-based (such as NiCrAlY) or cobalt-based (such as CoNiCrAlY) high-temperature alloys, while providing a stable adhesion substrate for the upper ceramic coating. The insulation ceramic layer is the core protective layer, and its mainstream material is yttrium-stabilized zirconium oxide (YSZ). With its extremely low thermal conductivity (only 1.5~2.5 W / (m·K) at room temperature, and even lower at high temperatures), excellent high-temperature chemical stability, and thermal expansion coefficient matching the bonding layer, this material can effectively block the heat transfer from high-temperature combustion gases to the substrate, reducing the temperature of the flame tube substrate by 150℃~300℃, and significantly improving its temperature resistance.

[0004] Furthermore, for complex-shaped and multi-aperture flame tubes, the tube body has different curvatures and is also covered with various shapes and sizes of openings, including air guide holes, air film holes, and crack-prevention holes. The shapes of the holes are circular, square, and elliptical. Traditional spraying processes can lead to poor uniformity of the thermal barrier coating after spraying, with large deviations in coating thickness in different areas (including the tube body and the opening structure of the flame tube), which in turn affects the subsequent performance, such as causing defects such as thermal barrier coating peeling and cracking.

[0005] Therefore, how to provide a spraying process for thermal barrier coatings that can be applied to complex-shaped and multi-aperture flame tubes, ensuring uniform thickness of the thermal barrier coating and eliminating defects such as separation, cracking, peeling, and flaking during application, is a technical problem that urgently needs to be solved. Summary of the Invention

[0006] To address the aforementioned technical problems, this invention provides a thermal barrier coating for a complex-shaped, multi-aperture flame tube and its spraying method. This invention combines supersonic flame spraying with segmented spraying for the metal bonding layer. By adjusting the spray gun movement speeds of the first, second, third, and fourth sprays according to the complex shape and multiple openings of the flame tube, the thickness of the metal bonding layer on the flame tube can be made uniform across its various parts, with minimal thickness deviation, high bonding strength, low porosity, uniform coating structure, and no delamination, interface separation, or cracks. Similarly, this invention combines atmospheric plasma spraying with segmented spraying for the ceramic surface layer. By adjusting the spray gun movement speeds of the fifth, sixth, seventh, and eighth sprays according to the complex shape and multiple openings of the flame tube, the thickness of the ceramic surface layer on the metal bonding layer can be made uniform across its various parts, with minimal thickness deviation, high bonding strength, low interface contamination, uniform coating structure, and no delamination, interface separation, or cracks. The resulting thermal barrier coating exhibits superior overall performance. After undergoing thermal cycling fatigue testing, it remained free from defects such as separation, cracking, peeling, and flaking, thus effectively enhancing its resistance to thermal shock and flaking during use.

[0007] To achieve this objective, the present invention adopts the following technical solution:

[0008] In a first aspect, the present invention provides a method for spraying a thermal barrier coating on a complex-shaped flame tube with multiple openings, the spraying method comprising the following steps:

[0009] (1) Provide a complex-shaped flame tube with multiple openings: the complex-shaped flame tube with multiple openings includes a tube body and openings. The tube body includes a first tube body, a second tube body and a third tube body connected in sequence. The openings include a first opening and a second opening. The first tube body includes a first opening and the third tube body includes a second opening.

[0010] (2) Spraying a metal bonding layer: The second opening is masked, and the inner wall of the first section of the cylinder is sprayed in sequence, the inner wall of the second section of the cylinder is sprayed in sequence, and the inner wall of the third section of the cylinder is sprayed in sequence; the edge area of ​​the first opening is masked, and the inner wall of the first opening is sprayed in sequence to form a metal bonding layer.

[0011] The spray guns for the first spray, the second spray, the third spray, and the fourth spray have different moving speeds;

[0012] (3) Spraying ceramic surface layer: The second opening is masked, and a fifth spray is applied to the metal bonding layer surface of the first section of the cylinder, a sixth spray is applied to the metal bonding layer surface of the second section of the cylinder, and a seventh spray is applied to the metal bonding layer surface of the third section of the cylinder; the edge area of ​​the first opening is masked, and an eighth spray is applied to the metal bonding layer surface of the first opening to form a ceramic surface layer and obtain a thermal barrier coating.

[0013] The spray guns for the fifth, sixth, seventh, and eighth sprays move at different speeds.

[0014] In this invention, supersonic flame spraying and segmented spraying are combined for spraying the metal bonding layer. The spray gun movement speeds for the first, second, third, and fourth sprays are adjusted according to the complex shape and multiple openings of the flame tube, resulting in uniform thickness of the metal bonding layer on the flame tube, minimizing thickness deviation, achieving high bonding strength, low porosity, uniform coating structure, and eliminating delamination, interface separation, and cracks. Similarly, atmospheric plasma spraying and segmented spraying are combined for spraying the ceramic surface layer. The spray gun movement speeds for the fifth, sixth, seventh, and eighth sprays are adjusted according to the complex shape and multiple openings of the flame tube, resulting in uniform thickness of the ceramic surface layer on the metal bonding layer, minimizing thickness deviation, achieving high bonding strength, low interface contamination, uniform coating structure, and eliminating delamination, interface separation, and cracks.

[0015] The thermal barrier coating obtained by this invention has superior overall performance. After thermal cycling fatigue testing, it still shows no defects such as separation, cracks, peeling, or flaking, thus effectively improving its resistance to thermal shock and flaking during use.

[0016] As a preferred technical solution of the present invention, in step (1), the first section of the cylinder is a cylinder, and the diameter of the upper bottom surface and the diameter of the lower bottom surface of the first section of the cylinder are the same.

[0017] Preferably, in step (1), the second section of the cylinder is a frustum, the diameter of the upper bottom surface of the second section of the cylinder is larger than the diameter of the lower bottom surface, and the diameter of the upper bottom surface of the second section of the cylinder is the same as the diameter of the lower bottom surface of the first section of the cylinder.

[0018] Preferably, the third section of the cylinder in step (1) is a semi-circular arc-shaped cylinder, and the bottom diameter of the third section of the cylinder is the same as the bottom diameter of the second section of the cylinder.

[0019] Preferably, in step (1), the first opening includes at least one set of openings arranged opposite to each other.

[0020] Preferably, in step (1), the first opening includes a circular opening and / or an elliptical opening, preferably an elliptical opening.

[0021] Preferably, in step (1), the second opening includes a circular opening.

[0022] As a preferred technical solution of the present invention, step (2) the first spraying includes at least two spraying processes.

[0023] Preferably, during at least two spraying processes of the first spraying, the first speed of the spray gun movement is the same.

[0024] Preferably, the first speed is 12mm / s to 15mm / s, such as 12mm / s, 12.5mm / s, 13mm / s, 13.5mm / s, 14mm / s, 14.5mm / s or 15mm / s, etc.

[0025] Preferably, step (2) the second spraying includes at least one spraying process.

[0026] Preferably, during at least one segment of the second spraying process, the second speed of the spray gun movement is the same.

[0027] Preferably, the second speed is 20mm / s to 30mm / s, such as 20mm / s, 21mm / s, 22mm / s, 23mm / s, 24mm / s, 25mm / s, 26mm / s, 27mm / s, 28mm / s, 29mm / s or 30mm / s, etc.

[0028] Preferably, the third spraying in step (2) includes a first spraying section and a second spraying section.

[0029] Preferably, in the arc surface of the semi-circular arc-shaped cylinder, the midpoint between the bottom edge and the edge of the second opening is denoted as point A. The area of ​​the first spraying process is the arc surface area corresponding to the distance from the bottom edge to point A, and the area of ​​the second spraying process is the arc surface area corresponding to the distance from point A to the edge of the second opening.

[0030] Preferably, the first spraying segment and the second spraying segment each independently include at least one spraying process.

[0031] Preferably, during at least one segment of the first spraying process, the spray gun moving speed and the third speed are all the same.

[0032] Preferably, the third velocity is 45mm / s to 65mm / s, such as 45mm / s, 48mm / s, 50mm / s, 52mm / s, 55mm / s, 58mm / s, 60mm / s, 62mm / s, or 65mm / s.

[0033] Preferably, during at least one segment of the second spraying process, the spray gun moving speed and the fourth speed are the same.

[0034] Preferably, the fourth velocity is 400mm / s to 1000mm / s, such as 400mm / s, 450mm / s, 500mm / s, 550mm / s, 600mm / s, 650mm / s, 700mm / s, 750mm / s, 800mm / s, 850mm / s, 900mm / s, 950mm / s, or 1000mm / s.

[0035] In this invention, the third spraying process employs a two-stage spraying method. During the first stage of spraying, the third speed of the spray gun movement is controlled at 45mm / s to 65mm / s, and during the second stage, the fourth speed is controlled at 400mm / s to 1000mm / s. This ensures that the thickness of the metal bonding layer obtained from the first and second spraying processes is uniform. If the two spraying processes of the third stage maintain the same speed, the difference in curvature of the sprayed area will result in an excessively large difference in the thickness of the metal bonding layer obtained in the first and second sprayed areas, failing to meet the requirement of uniformity. If the fourth speed during the second stage is too low, the single-layer deposition thickness of the metal bonding layer in the second sprayed area will be excessive, leading to excessive porosity and reduced bonding strength. If the fourth speed during the second stage is too high, the single-layer deposition thickness of the metal bonding layer in the second sprayed area will be too thin, and the coating will be discontinuous and uneven.

[0036] As a preferred technical solution of the present invention, the fourth spraying in step (2) adopts segmented spraying, which includes first spraying the inner walls of the opposite sides of the first opening, and then spraying the remaining inner walls of the opposite sides.

[0037] Preferably, the metal bonding layers in each area obtained by the segmented spraying are joined in a stepped manner.

[0038] In this invention, the metal bonding layers in each region obtained by segmented spraying are overlapped in a stepped manner, which can ensure the uniformity of the thickness of the metal bonding layers in each sprayed region.

[0039] Preferably, in the fourth spraying process described in step (2), the spray gun moving speed and the fifth speed are the same.

[0040] Preferably, the fifth velocity is 900mm / s to 1000mm / s, such as 900mm / s, 910mm / s, 920mm / s, 930mm / s, 940mm / s, 950mm / s, 960mm / s, 970mm / s, 980mm / s, 990mm / s, or 1000mm / s.

[0041] Preferably, in the fourth spraying process described in step (2), the spray gun stepping distance is the same.

[0042] Preferably, the spray gun step distance is 4mm to 5mm, such as 4mm, 4.2mm, 4.5mm, 4.8mm or 5mm.

[0043] In this invention, the spray gun movement speeds during the first, second, third, and fourth spraying processes are matched to adapt to the complex shapes of different areas of the flame tube, thereby minimizing the thickness deviation of the resulting metal adhesive layer and ensuring thickness uniformity.

[0044] As a preferred technical solution of the present invention, the fifth spraying in step (3) includes at least two spraying processes.

[0045] Preferably, during at least two stages of the fifth spraying process, the spray gun moving speed is the same.

[0046] Preferably, the sixth velocity is 5 mm / s to 8 mm / s, such as 5 mm / s, 5.5 mm / s, 6 mm / s, 6.5 mm / s, 7 mm / s, 7.5 mm / s, or 8 mm / s.

[0047] Preferably, the sixth spraying in step (3) includes at least one spraying process.

[0048] Preferably, during at least one segment of the sixth spraying process, the spray gun moving speed and the seventh speed are the same.

[0049] Preferably, the seventh velocity is 8 mm / s to 11 mm / s, such as 8 mm / s, 8.5 mm / s, 9 mm / s, 9.5 mm / s, 10 mm / s, 10.5 mm / s, or 11 mm / s.

[0050] Preferably, the seventh spraying in step (3) includes a first spraying stage and a second spraying stage.

[0051] Preferably, in the arc surface of the semi-circular arc-shaped cylinder, the midpoint between the bottom edge and the edge of the second opening is denoted as point A. The area of ​​the first spraying process is the arc surface area corresponding to the distance from the bottom edge to point A, and the area of ​​the second spraying process is the arc surface area corresponding to the distance from point A to the edge of the second opening.

[0052] Preferably, the first spraying segment and the second spraying segment each independently include at least one spraying process.

[0053] Preferably, during at least one segment of the first spraying process, the spray gun moving speed is the same.

[0054] Preferably, the eighth velocity is 13mm / s to 16mm / s, such as 13mm / s, 13.5mm / s, 14mm / s, 14.5mm / s, 15mm / s, 15.5mm / s, or 16mm / s.

[0055] Preferably, during at least one segment of the second spraying process, the spray gun moving speed is the same.

[0056] Preferably, the ninth speed is 200mm / s to 300mm / s, such as 200mm / s, 210mm / s, 220mm / s, 230mm / s, 240mm / s, 250mm / s, 260mm / s, 270mm / s, 280mm / s, 290mm / s, or 300mm / s.

[0057] In this invention, the seventh spraying process employs a two-stage spraying method. During the first stage of spraying, the spray gun movement speed (eighth speed) is adjusted to 13mm / s~16mm / s, and during the second stage, the spray gun movement speed (ninth speed) is adjusted to 200mm / s~300mm / s. This ensures that the ceramic surface layer obtained from the first and second spraying processes has a uniform thickness. If the two spraying processes in the seventh stage maintain the same speed, the difference in curvature of the sprayed area will result in an excessively large difference in the thickness of the ceramic surface layer obtained in the first and second sprayed areas, failing to meet the requirement of uniformity. If the ninth speed during the seventh stage is too low, the single-layer deposition thickness of the ceramic surface layer in the second sprayed area will be too large, reducing the coating bonding strength and leading to partial coating peeling during thermal fatigue testing. If the ninth speed during the seventh stage is too high, the single-layer deposition thickness of the ceramic surface layer in the second sprayed area will be too thin, resulting in discontinuous coating thickness. Areas with thinner coatings will have poor thermal insulation performance, increasing the risk of substrate over-oxidation during thermal fatigue testing.

[0058] As a preferred technical solution of the present invention, the eighth spraying in step (3) adopts segmented spraying, which includes first spraying the opposite metal bonding layer surfaces in the first opening, and then spraying the remaining opposite metal bonding layer surfaces on both sides.

[0059] Preferably, the ceramic surface layers in each area obtained by the segmented spraying are joined in a stepped manner.

[0060] In this invention, the ceramic surface layers in each region obtained by segmented spraying are overlapped in a stepped manner, which can ensure the uniformity of the thickness of the ceramic surface layer in each sprayed region.

[0061] Preferably, in the eighth spraying process described in step (3), the spray gun moving speed and the tenth speed are the same.

[0062] Preferably, the tenth velocity is 500mm / s to 600mm / s, such as 500mm / s, 510mm / s, 520mm / s, 530mm / s, 540mm / s, 550mm / s, 560mm / s, 570mm / s, 580mm / s, 590mm / s, or 600mm / s.

[0063] Preferably, in the eighth spraying process described in step (3), the spray gun stepping distance is the same.

[0064] Preferably, the spray gun step distance is 4mm to 5mm, such as 4mm, 4.2mm, 4.5mm, 4.8mm or 5mm.

[0065] In this invention, the spray gun movement speeds during the fifth, sixth, seventh, and eighth spraying processes are matched to adapt to the complex surface of each area of ​​the flame tube, thereby minimizing the thickness deviation of the resulting ceramic surface layer and ensuring thickness uniformity.

[0066] As a preferred technical solution of the present invention, the metal bonding layer in step (2) is sprayed using a supersonic flame spraying method.

[0067] This invention uses supersonic flame spraying to prepare a metal bonding layer, and sprays the cylinder and openings of the flame tube in segments. That is, by combining supersonic flame spraying and segmented spraying, the thickness of the metal bonding layer on the flame tube can be made uniform in all parts, and the thickness deviation can be minimized. This improves the resistance to thermal shock and peeling during use, extends the service life, reduces maintenance costs, and ensures structural strength and operational safety.

[0068] Preferably, the coating material for the metal bonding layer includes CoNiCrAlY alloy powder.

[0069] Preferably, the average particle size of the CoNiCrAlY alloy powder is 8μm to 13μm, such as 8μm, 9μm, 10μm, 11μm, 12μm or 13μm.

[0070] Preferably, based on a total mass of 100wt% of the CoNiCrAlY alloy powder, the CoNiCrAlY alloy powder comprises 31.8wt%~34.8wt% of Ni, such as 31.8wt%, 32.8wt%, 33.8wt%, or 34.8wt%, etc.; 19.5wt%~20.5wt% of Cr, such as 19.5wt%, 19.8wt%, 20.0wt%, 20.2wt%, or 20.5wt%, etc.; 6.6wt%~9.6wt% of Al, such as 6.6wt%, 7.6wt%, 8.6wt%, or 9.6wt%, etc.; 0.28wt%~0.68wt% of Y, such as 0.28wt%, 0.38wt%, 0.48wt%, 0.58wt%, or 0.68wt%, etc.; and the balance Co.

[0071] Preferably, the powder feeding rate of the supersonic flame spraying method is 4 g / min to 8 g / min, such as 4 g / min, 5 g / min, 6 g / min, 7 g / min or 8 g / min.

[0072] Preferably, the kerosene flow rate of the supersonic flame spraying method is 4.6L / min to 7.8L / min, such as 4.6L / min, 5.0L / min, 5.5L / min, 6.0L / min, 6.5L / min, 7.0L / min or 7.8L / min.

[0073] Preferably, the hydrogen flow rate of the supersonic flame spraying method is 30L / min to 60L / min, such as 30L / min, 35L / min, 40L / min, 45L / min, 50L / min, 55L / min or 60L / min.

[0074] Preferably, the nitrogen flow rate of the supersonic flame spraying method is 40L / min to 85L / min, such as 40L / min, 45L / min, 50L / min, 55L / min, 60L / min, 65L / min, 70L / min, 75L / min, 80L / min or 85L / min.

[0075] Preferably, the oxygen flow rate of the supersonic flame spraying method is 160L / min to 220L / min, such as 160L / min, 170L / min, 180L / min, 190L / min, 200L / min, 210L / min or 220L / min.

[0076] Preferably, the spraying distance of the supersonic flame spraying method is 10mm~50mm, such as 10mm, 15mm, 20mm, 25mm, 30mm, 35mm, 40mm, 45mm or 50mm.

[0077] Preferably, the ceramic surface layer in step (3) is sprayed using atmospheric plasma spraying.

[0078] Preferably, the coating material for the ceramic surface layer includes a mixture of yttrium oxide-stabilized zirconia powder.

[0079] Preferably, based on a total mass of 100 wt% of the yttrium oxide-stabilized zirconia mixed powder, the yttrium oxide-stabilized zirconia mixed powder comprises 6.0 wt% to 9.0 wt% of yttrium oxide, such as 6.0 wt%, 7.0 wt%, 8.0 wt%, or 9.0 wt%, and 91.0 wt% to 94.0 wt% of zirconia, such as 91.0 wt%, 92.0 wt%, 93.0 wt%, or 94.0 wt%, etc.

[0080] Preferably, the powder feeding rate of the atmospheric plasma spraying method is 20 g / min to 40 g / min, such as 20 g / min, 25 g / min, 30 g / min, 35 g / min or 40 g / min.

[0081] Preferably, the hydrogen flow rate of the atmospheric plasma spraying method is 8L / min to 15L / min, such as 8L / min, 9L / min, 10L / min, 11L / min, 12L / min, 13L / min, 14L / min or 15L / min.

[0082] Preferably, the argon flow rate of the atmospheric plasma spraying method is 40L / min to 58L / min, such as 40L / min, 42L / min, 45L / min, 48L / min, 50L / min, 52L / min, 55L / min or 58L / min.

[0083] Preferably, the pressure of the cooling gas in the atmospheric plasma spraying method is 3 bar to 6 bar, such as 3 bar, 3.5 bar, 4 bar, 4.5 bar, 5 bar, 5.5 bar or 6 bar.

[0084] Preferably, the spraying distance of the atmospheric plasma spraying method is 30mm~70mm, such as 30mm, 35mm, 40mm, 45mm, 50mm, 55mm, 60mm, 65mm or 70mm.

[0085] As a preferred technical solution of the present invention, step (1) further includes degreasing the complex surface and multi-hole flame tube and sandblasting the surface to be sprayed to obtain the complex surface and multi-hole flame tube to be sprayed.

[0086] Preferably, the sand used in the sandblasting process is 40 to 60 mesh, such as 40 mesh, 50 mesh, or 60 mesh.

[0087] Preferably, the linear velocity of the sandblasting process is 5 m / min to 15 m / min, such as 5 m / min, 8 m / min, 10 m / min, 12 m / min or 15 m / min.

[0088] Preferably, the step distance of the sandblasting process is 5mm to 15mm, such as 5mm, 6mm, 7mm, 8mm, 9mm, 10mm, 11mm, 12mm, 13mm, 14mm or 15mm.

[0089] Preferably, the sandblasting distance is 40mm to 60mm, such as 40mm, 42mm, 45mm, 48mm, 50mm, 52mm, 55mm, 58mm or 60mm.

[0090] Preferably, the sandblasting angle of the sandblasting process is 40 degrees to 50 degrees, such as 40 degrees, 42 degrees, 45 degrees, 48 ​​degrees or 50 degrees.

[0091] Preferably, the pressure of the sandblasting process is 2 bar to 4 bar, such as 2 bar, 3 bar or 4 bar.

[0092] Preferably, the number of sandblasting treatments is 1 to 2, for example, once or twice.

[0093] Preferably, after the sandblasting treatment, the roughness Ra of the surface to be coated is 2μm~4μm, such as 2μm, 2.2μm, 2.5μm, 2.8μm, 3μm, 3.2μm, 3.5μm, 3.8μm or 4μm.

[0094] Preferably, a through-hole step is included between steps (2) and (3).

[0095] Preferably, after obtaining the thermal barrier coating in step (3), the step of creating through holes is further included.

[0096] In this invention, through holes are made after the metal bonding layer and thermal barrier coating are obtained by spraying, which can effectively avoid coating cracking at the opening edge and out-of-tolerance hole size.

[0097] In a second aspect, the present invention also provides a thermal barrier coating for a complex-shaped and multi-aperture flame tube obtained by spraying according to the spraying method described in the first aspect, the thermal barrier coating comprising a metal bonding layer and a ceramic surface layer located on the surface of the metal bonding layer, wherein the metal bonding layer is located on the inner wall surface of the complex-shaped and multi-aperture flame tube.

[0098] As a preferred technical solution of the present invention, the average thickness of the thermal barrier coating is 0.25mm~0.35mm, for example, 0.25mm, 0.26mm, 0.27mm, 0.28mm, 0.29mm, 0.30mm, 0.31mm, 0.32mm, 0.33mm, 0.34mm or 0.35mm.

[0099] Preferably, the thickness deviation of the thermal barrier coating is ≤10%, for example, 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%, 1% or 0.5%.

[0100] Preferably, the average thickness of the metal bonding layer is 0.05mm to 0.15mm, such as 0.05mm, 0.06mm, 0.07mm, 0.08mm, 0.09mm, 0.10mm, 0.11mm, 0.12mm, 0.13mm, 0.14mm or 0.15mm.

[0101] Preferably, the thickness deviation of the metal bonding layer is ≤8.5%, for example, 8.5%, 8%, 7.5%, 7%, 6%, 5%, 4%, 3%, 2%, 1% or 0.5%.

[0102] Preferably, the bonding strength of the metal bonding layer is ≥80MPa, such as 80MPa, 82MPa, 85MPa, 88MPa, 90MPa, 92MPa, 95MPa, 98MPa, 100MPa or 120MPa.

[0103] Preferably, the porosity of the metal bonding layer is ≤0.2%, for example, 0.2%, 0.18%, 0.15%, 0.12%, 0.1%, 0.08%, 0.05%, 0.02%, 0.01%, or 0.005%.

[0104] Preferably, the bonding strength of the ceramic surface layer is ≥24MPa, such as 24MPa, 25MPa, 28MPa, 30MPa, 32MPa, 35MPa, 38MPa, 40MPa or 50MPa.

[0105] Preferably, the interface contamination of the ceramic surface layer is ≤10%, such as 10%, 8%, 5%, 2%, 1% or 0.5%.

[0106] Compared with the prior art, the present invention has at least the following beneficial effects:

[0107] 1) This invention combines supersonic flame spraying with segmented spraying for the coating of a metal bonding layer. The moving speeds of the spray guns for the first, second, third, and fourth sprays are adjusted according to the complex shape and multiple openings of the flame tube, resulting in uniform thickness of the metal bonding layer on the flame tube, minimizing thickness deviation, achieving high bonding strength, low porosity, uniform coating structure, and eliminating delamination, interface separation, and cracks. Similarly, this invention combines atmospheric plasma spraying with segmented spraying for the coating of a ceramic surface layer. The moving speeds of the spray guns for the fifth, sixth, seventh, and eighth sprays are adjusted according to the complex shape and multiple openings of the flame tube, resulting in uniform thickness of the ceramic surface layer on the metal bonding layer, minimizing thickness deviation, achieving high bonding strength, low interface contamination, uniform coating structure, and eliminating delamination, interface separation, and cracks.

[0108] 2) The thickness deviation of the thermal barrier coating obtained by spraying in this invention is ≤10% at all points, of which the thickness deviation of the metal bonding layer is ≤8.5%, the bonding strength is ≥80MPa, the porosity is ≤0.2%, the bonding strength of the ceramic surface layer is ≥24MPa, the interface contamination is ≤10%, the overall performance of the thermal barrier coating is superior, and there are no defects such as separation, cracks, peeling, or flaking after thermal cycling fatigue testing, thereby effectively improving the thermal shock resistance and anti-peeling ability during use. Attached Figure Description

[0109] Figure 1 This is a schematic diagram of the complex surface and multi-hole flame tube structure provided by the present invention.

[0110] Figure 2 This is a structural schematic diagram of the complex-shaped flame tube with multiple openings and the shielding fixture provided by the present invention.

[0111] Figure 3 This is a spraying path diagram of the metal bonding layer in the cylindrical part of Embodiment 1 of the present invention.

[0112] Figure 4 This is a schematic diagram and path diagram of the spraying of the metal adhesive layer on the elliptical second opening portion in Embodiment 1 of the present invention.

[0113] Among them, 1-cylinder body, 11-first section of cylinder body, 12-second section of cylinder body, 13-third section of cylinder body, 2-opening, 21-elliptical first opening, 22-circular second opening, 3-first shielding fixture, 4-second shielding fixture, 5-spray gun. Detailed Implementation

[0114] The technical solution of the present invention will be further described below with reference to the accompanying drawings and specific embodiments. However, the following examples are merely simplified examples of the present invention and do not represent or limit the scope of protection of the present invention. The scope of protection of the present invention is determined by the claims.

[0115] Unless otherwise stated, the raw materials and reagents used in the following examples are commercially available products or can be prepared by known methods.

[0116] In a specific embodiment of this invention, the metal bonding layer is coated using an ultrafine powder dual-fuel supersonic flame spraying system (Zhongji Kaibo Nano-HVOF supersonic flame spraying equipment) with a 45-degree small inner orifice spray gun. The spray gun has two cooling gas paths perpendicular to the flame axis, and two auxiliary cooling paths externally, which can prevent the flame tube from overheating and turning blue. The ceramic surface layer is coated using atmospheric plasma spraying, and the spraying equipment is a Metco Unicoatpro2086 model 45-degree spray gun.

[0117] The coating material for the metal bonding layer is a CoNiCrAlY alloy powder with an average particle size of 10μm, containing 32.8wt% Ni, 20.0wt% Cr, 7.0wt% Al, 0.48wt% Y and the balance Co.

[0118] The coating material for the ceramic surface layer is a yttrium oxide-stabilized zirconia mixture powder, containing 8.0 wt% yttrium oxide and 92.0 wt% zirconia.

[0119] Figure 1 The diagram shows a complex surface and multi-aperture flame tube structure provided by the present invention, including a tube body 1 and openings 2. The tube body 1 includes a first tube body 11, a second tube body 12 and a third tube body 13 connected in sequence. The openings 2 include an elliptical first opening 21 and a circular second opening 22. A set of elliptical first openings are arranged opposite each other on the first tube body, and a circular second opening is arranged on the third tube body.

[0120] Figure 2 The diagram shows a complex-shaped flame tube with multiple openings and a shielding fixture provided by the present invention. The first shielding fixture 3 is used to shield the circular second opening 22, and the second shielding fixture 4 is used to shield the edge area of ​​the elliptical first opening 21.

[0121] Example 1

[0122] This embodiment provides a method for spraying a thermal barrier coating on a complex-shaped flame tube with multiple openings. The spraying method includes the following steps:

[0123] (1) Provide complex-shaped and multi-hole flame tubes;

[0124] Use lint-free paper soaked in anhydrous ethanol to clean the entire surface of complex shapes and multi-hole flame tubes to remove oil stains. When a clean lint-free paper is used to wipe the surface of the workpiece, there are no stains left on the lint-free paper, indicating that the degreasing is complete.

[0125] All surfaces to be coated were sandblasted to improve the adhesion of the coating after spraying. The sandblasting parameters were: 60 mesh size, 12 m / min linear speed, 8 mm step, 50 mm spraying distance, 45 degrees spraying angle, and 3 bar pressure. The roughness Ra of all surfaces to be coated after sandblasting was 3.2 μm.

[0126] (2) The metal bonding layer is applied using a supersonic flame spraying method. Figure 3 The diagram shows the spraying path of the metal bonding layer for the cylindrical part in Embodiment 1 of the present invention. The specific process includes: masking the second circular opening with a first masking fixture; spraying the inner wall of the first section of the cylindrical part with a spray gun 5 in sequence; the first spraying is divided into two spraying processes, P1-P2 and P2-P3, with P1-P2 sprayed at a first speed of 13 mm / s and P2-P3 sprayed at a first speed of 13 mm / s; then spraying the inner wall of the second section of the cylindrical part with a second spraying process, P3-P4, with the second speed of the spray gun movement being 25 mm / s; then spraying the inner wall of the third section of the cylindrical part with a third spraying process, including the first spraying of P4-P5 and the second spraying of P5-P6, with P4-P5 sprayed at a third speed of 55 mm / s and P5-P6 sprayed at a fourth speed of 700 mm / s, thus forming the metal bonding layer for the cylindrical part.

[0127] Figure 4 This diagram illustrates the spraying process and path of the metal bonding layer on the elliptical second opening portion in Embodiment 1 of the present invention. The specific process includes: masking the edge area of ​​the elliptical second opening using a second masking fixture; performing a fourth spraying on the inner wall of the elliptical second opening, wherein the fourth spraying is done in segments, consisting of four segments: first, areas S1 and S2 are sprayed, with the edge transition area sprayed in a stepped manner; then, areas S3 and S4 are sprayed, with the edge transition area overlapping the steps of areas S1 and S2. The fifth speed of the spray gun is 1000 mm / s, with a step of 4.5 mm. The metal bonding layers of each sprayed area obtained by segmented spraying adopt a stepped overlapping method to form the metal bonding layer of the elliptical second opening. The process parameters of the supersonic flame spraying method are: powder feeding rate 7 g / min, kerosene flow rate 6.0 L / min, hydrogen flow rate 50 L / min, nitrogen flow rate 55 L / min, oxygen flow rate 180 L / min, and spraying distance 45 mm.

[0128] After spraying, remove the first and second masking fixtures. Use a diamond file to repair the oversprayed areas of the second circular opening and the tail opening to prevent subsequent coating cracking. Manually grind all openings that have reduced diameter or have been oversprayed after spraying. Use a soft diamond wire saw to grind small holes and use a diamond grinding needle at the highest speed (2000 r / min) to grind the remaining larger holes. Maintaining the highest speed can prevent hole gaps.

[0129] (3) The ceramic surface layer is sprayed using atmospheric plasma spraying. The spraying path of the ceramic surface layer on the cylinder part is consistent with the spraying path of the metal bonding layer on the cylinder part. The specific process includes: the second circular opening is masked using the first masking fixture, and the metal bonding layer surface of the first section of the cylinder is sprayed with a spray gun in sequence for the fifth spraying. The fifth spraying is divided into two spraying processes: P1-P2 and P2-P3. First, P1-P2 is sprayed at a sixth speed of 6 mm / s, and then P2-P3 is sprayed at a sixth speed of 6 mm / s. 2-P3; Then, the metal bonding layer surface of the second section of the cylinder is coated with a sixth spray, which is a spray process from P3 to P4. The seventh speed of the spray gun movement is 10 mm / s. Then, the metal bonding layer surface of the third section of the cylinder is coated with a seventh spray, which includes the first spray from P4 to P5 and the second spray from P5 to P6. First, P4 to P5 is sprayed at an eighth speed of 15 mm / s, and then P5 to P6 is sprayed at a ninth speed of 260 mm / s to form the ceramic surface layer of the cylinder.

[0130] The spraying path of the ceramic surface layer in the elliptical second opening is consistent with the spraying path of the metal bonding layer in the elliptical second opening. The specific process includes: using a second masking fixture to mask the edge area of ​​the elliptical second opening; performing an eighth spraying on the inner wall of the elliptical second opening, wherein the eighth spraying adopts a segmented spraying method, which is divided into four segments. First, the S1 and S2 areas are sprayed, and the edge transition area is sprayed in a stepped manner. Then, the S3 and S4 areas are sprayed, and the edge transition area overlaps with the steps of the S1 and S2 areas. The spray gun moving speed is 600 mm / s, and the step is 4.5 mm. The ceramic surface layers of each sprayed area obtained by segmented spraying are overlapped in a stepped manner to form the ceramic surface layer of the elliptical second opening. The process parameters of the atmospheric plasma spraying method are: powder feeding rate 35 g / min, hydrogen flow rate 12 L / min, argon flow rate 55 L / min, cooling gas pressure 5.5 bar, and spraying distance 50 mm.

[0131] After spraying, remove the first and second masking fixtures. Use a diamond file to repair the oversprayed areas of the second circular opening and the tail opening to prevent subsequent coating cracking. Manually grind all openings with reduced or oversprayed diameters after spraying. Use a soft diamond wire saw to grind small holes and a diamond grinding needle at the highest speed (2000 r / min) to grind the remaining larger holes. Maintaining the highest speed can prevent hole gaps, thereby forming a thermal barrier coating on complex surfaces and multi-opening flame tubes.

[0132] The spraying methods for the thermal barrier coatings in Examples 2-5 and Comparative Examples 1-2 are based on Example 1 with parameter changes. The specific parameters changed in Examples 2-5 and Comparative Examples 1-2 are shown in Table 1.

[0133] Table 1

[0134]

[0135] Example 6

[0136] This embodiment provides a method for spraying a thermal barrier coating on a complex-shaped and multi-hole flame tube. The difference between the spraying method and that in Embodiment 1 is that the metal bonding layer in step (2) is sprayed using atmospheric plasma spraying. The process parameters of atmospheric plasma spraying are: powder feeding rate of 60 g / min, hydrogen flow rate of 8 L / min, argon flow rate of 50 L / min, cooling gas pressure of 5 bar, and spraying distance of 60 mm. The remaining preparation methods and parameters are consistent with those in Embodiment 1.

[0137] Example 7

[0138] This embodiment provides a method for spraying a thermal barrier coating on a complex-shaped flame tube with multiple openings. The difference between the spraying method and that in Embodiment 1 is that, in steps (2) and (3), the edge transition areas of the metal bonding layer and ceramic surface layer of the elliptical second opening are aligned and not overlapped in a stepped manner. The other preparation methods and parameters are consistent with those in Embodiment 1.

[0139] The average thickness, thickness deviation at various locations, bonding strength, and porosity of the metal bonding layers provided in Examples 1-7 and Comparative Examples 1-2 were tested. The bonding strength and interface contamination of the ceramic surface layer were tested. The average thickness and thickness deviation at various locations of the thermal barrier coating were tested. Thermal cycling fatigue tests were also conducted. The thermal cycling fatigue test method included: holding the thermal barrier coating at 1100±10℃ for 5-10 minutes, then rapidly quenching it in cold water at 20±5℃, and cycling it 30 times; heating it to 1100±10℃ in an oxyacetylene flame, then air-cooling it to <100℃, and cycling it 3000 times. The quality of the thermal barrier coating was observed. The specific test results are shown in Table 2.

[0140] Table 2

[0141]

[0142] The test results show that:

[0143] (1) As can be seen from Examples 1 to 3, the present invention combines supersonic flame spraying and segmented spraying to spray the metal bonding layer. The moving speed of the spray guns for the first, second, third and fourth sprays is adjusted according to the complex shape and multiple openings of the flame tube, so that the thickness of each part of the metal bonding layer on the flame tube is uniform, the thickness deviation is minimized, the bonding strength is high, the porosity is low, the coating structure is uniform, there is no delamination or interface separation, and there are no cracks. The present invention combines atmospheric plasma spraying and segmented spraying to spray the ceramic surface layer. The moving speed of the spray guns for the fifth, sixth, seventh and eighth sprays is adjusted according to the complex shape and multiple openings of the flame tube, so that the thickness of each part of the ceramic surface layer on the metal bonding layer is uniform, the thickness deviation is minimized, the bonding strength is high, the interface contamination is low, the coating structure is uniform, there is no delamination or interface separation, and there are no cracks. The obtained thermal barrier coating has excellent overall performance, with thickness deviation ≤10% at all locations. Specifically, the thickness deviation of the metal bonding layer is ≤8.5%, the bonding strength is ≥80MPa, the porosity is ≤0.2%, the bonding strength of the ceramic surface layer is ≥24MPa, and the interface contamination is ≤10%. After thermal cycling fatigue testing, there are still no defects such as separation, cracks, peeling, or flaking, all of which meet the design requirements and effectively improve the thermal shock resistance and anti-peeling ability during use.

[0144] (2) As can be seen from Examples 1 and 4-5, the spraying process of the third section of the cylinder was divided into two sections with different speeds. If the spraying speeds of the third and seventh spraying processes are kept consistent, the difference in curvature of the sprayed area will result in an excessively large difference in the thickness of the metal bonding layer and the ceramic surface layer obtained in the first and second sprayed areas, which will not meet the requirement of uniformity. Specifically, when the spraying speed of the P5-P6 section in Example 4 is too low, both the metal bonding layer and the ceramic surface layer are too thick in this area, resulting in an excessively large average thickness of the thermal barrier coating. The bonding strength of the metal bonding layer is only 70 MPa, and the bonding strength of the ceramic surface layer is 21 MPa, which is lower than the design requirements. Moreover, due to the excessively low spraying speed, the single-layer deposition rate is too high, which in turn increases the porosity to 0.5%. The thickness deviation of the thermal barrier coating at various locations reaches 85.3%, which is far beyond the design requirements. When the spraying speed of the P5-P6 section in Example 5 is too high, the thermal barrier coating becomes discontinuous and thin, resulting in incomplete coverage. After the thermal cycle fatigue test, the substrate (flame tube) of the thermal barrier coating oxidizes, and the thickness deviation at various points is as high as 79.6%, and the thickness deviation at various points of the metal bonding layer is as high as 65.5%, far exceeding the design requirements.

[0145] (3) As can be seen from Examples 1 and 6-7, the metal bonding layer used in Example 6 with atmospheric plasma spraying has a porosity as high as 3.58%. During the thermal cycling fatigue test, due to the insufficient oxidation resistance of the metal bonding layer, the coating peeled off by more than 10 cm. 2 In Example 7, the coating was applied using an aligned edge transition area and a non-stepped overlap method, resulting in an excessively thick coating at the overlap location of the second opening. This not only caused the coating thickness deviation and porosity to exceed design requirements, but also led to excessive internal stress due to the uneven coating thickness during thermal cycling fatigue testing, resulting in coating peeling exceeding 1 cm at the second opening. 2 .

[0146] (4) As can be seen from Example 1 and Comparative Examples 1 and 2, the same spraying speed was used in the process of spraying the metal bonding layer in Comparative Example 1, resulting in a thickness deviation of up to 218.9% in various parts of the thermal barrier coating. During the thermal cycling fatigue test, the thermal barrier coating peeled off more than 10 cm. 2 In Comparative Example 2, the same spraying speed was used during the ceramic coating process, resulting in a thermal barrier coating thickness deviation as high as 187.5%, and the thermal barrier coating peeling was greater than 10 cm during thermal cycling fatigue testing. 2 .

[0147] In summary, this invention combines supersonic flame spraying with segmented spraying for coating the metal bonding layer. By adjusting the spray gun movement speeds of the first, second, third, and fourth sprays according to the complex shape and multiple openings of the flame tube, the thickness of the metal bonding layer on the flame tube can be made uniform across its various parts, with minimal thickness deviation, high bonding strength, low porosity, uniform coating structure, and no delamination, interface separation, or cracks. Similarly, by combining atmospheric plasma spraying with segmented spraying for coating the ceramic surface layer, the spray gun movement speeds of the fifth, sixth, seventh, and eighth sprays can be adjusted according to the complex shape and multiple openings of the flame tube, resulting in uniform thickness of the ceramic surface layer on the metal bonding layer surface, minimal thickness deviation, high bonding strength, low interface contamination, uniform coating structure, and no delamination, interface separation, or cracks. The resulting thermal barrier coating exhibits superior overall performance. After thermal cycling fatigue testing, it remains free from defects such as separation, cracking, peeling, and flaking, thus effectively enhancing its resistance to thermal shock and flaking during use.

[0148] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A method of spray coating a thermal barrier coating of a complex profile and multi-perforated flame tube, characterized in that, The spraying method comprises the following steps: (1) providing a complex profile and a multi-perforated flame tube: the complex profile and the multi-perforated flame tube comprise a cylinder body and perforations, the cylinder body comprises a first section cylinder body, a second section cylinder body and a third section cylinder body connected in sequence, the perforations comprise first perforations and second perforations, the first section cylinder body comprises the first perforations, and the third section cylinder body comprises the second perforations; (2) spraying a metal bonding layer: the second perforations are shielded, the inner wall of the first section cylinder body is subjected to first spraying, the inner wall of the second section cylinder body is subjected to second spraying, and the inner wall of the third section cylinder body is subjected to third spraying; the edge region of the first perforations is shielded, and the inner wall of the first perforations is subjected to fourth spraying to form a metal bonding layer; the spraying gun moving speeds of the first spraying, the second spraying, the third spraying and the fourth spraying are different; (3) spraying a ceramic surface layer: the second perforations are shielded, the metal bonding layer surface of the first section cylinder body is subjected to fifth spraying, the metal bonding layer surface of the second section cylinder body is subjected to sixth spraying, and the metal bonding layer surface of the third section cylinder body is subjected to seventh spraying; the edge region of the first perforations is shielded, and the metal bonding layer surface of the first perforations is subjected to eighth spraying to form a ceramic surface layer, thereby obtaining a thermal barrier coating; the spraying gun moving speeds of the fifth spraying, the sixth spraying, the seventh spraying and the eighth spraying are different.

2. The spray method according to claim 1, characterized in that, In step (1), the first section cylinder body is a cylinder, and the upper bottom surface diameter of the first section cylinder body is the same as the lower bottom surface diameter. Preferably, in step (1), the second section cylinder body is a circular truncated cone, the upper bottom surface diameter of the second section cylinder body is greater than the lower bottom surface diameter, and the upper bottom surface diameter of the second section cylinder body is the same as the lower bottom surface diameter of the first section cylinder body. Preferably, in step (1), the third section cylinder body is a semicircular arc cylinder body, and the bottom surface diameter of the third section cylinder body is the same as the lower bottom surface diameter of the second section cylinder body. Preferably, in step (1), the first perforations comprise at least one group of oppositely arranged perforations. Preferably, in step (1), the first perforations comprise circular perforations and / or elliptical perforations, preferably elliptical perforations. Preferably, in step (1), the second perforations comprise circular perforations.

3. The spray method of claim 2, wherein, In step (2), the first spraying comprises at least two spraying processes. Preferably, in the at least two spraying processes of the first spraying, the spraying gun moving speed is the same first speed. Preferably, the first speed is 12 mm / s to 15 mm / s. Preferably, in step (2), the second spraying comprises at least one spraying process. Preferably, in the at least one spraying process of the second spraying, the spraying gun moving speed is the same second speed. Preferably, the second speed is 20 mm / s to 30 mm / s. Preferably, in step (2), the third spraying comprises a first section spraying and a second section spraying. Preferably, in the arc surface of the semi-circular arc-shaped cylinder, the middle position from the bottom edge to the second opening edge is recorded as point A, the area of the first segment spraying process is the arc surface area corresponding to the distance from the bottom edge to the A point, and the area of the second segment spraying process is the arc surface area corresponding to the distance from the A point to the second opening edge. Preferably, the first segment spraying and the second segment spraying each independently comprise at least one segment spraying process. Preferably, in the at least one segment spraying process of the first segment spraying, the moving speed of the spray gun is a third speed. Preferably, the third speed is 45 mm / s to 65 mm / s. Preferably, in the at least one segment spraying process of the second segment spraying, the moving speed of the spray gun is a fourth speed. Preferably, the fourth speed is 400 mm / s to 1000 mm / s.

4. The spray coating method according to any one of claims 1 to 3, characterized in that, The fourth spraying in step (2) adopts segment spraying, and the segment spraying comprises spraying the opposite inner walls in the first opening first and then spraying the remaining opposite inner walls. Preferably, the metal bonding layers obtained by the segment spraying are connected in a stepped manner. Preferably, in the fourth spraying process in step (2), the moving speed of the spray gun is a fifth speed. Preferably, the fifth speed is 900 mm / s to 1000 mm / s. Preferably, in the fourth spraying process in step (2), the step distance of the spray gun is the same. Preferably, the step distance of the spray gun is 4 mm to 5 mm.

5. The spray method of claim 2, wherein, The fifth spraying in step (3) comprises at least two segment spraying processes. Preferably, in the at least two segment spraying processes of the fifth spraying, the moving speed of the spray gun is a sixth speed. Preferably, the sixth speed is 5 mm / s to 8 mm / s. Preferably, the sixth spraying in step (3) comprises at least one segment spraying process. Preferably, in the at least one segment spraying process of the sixth spraying, the moving speed of the spray gun is a seventh speed. Preferably, the seventh speed is 8 mm / s to 11 mm / s. Preferably, the seventh spraying in step (3) comprises a first segment spraying and a second segment spraying. Preferably, in the arc surface of the semi-circular arc-shaped cylinder, the middle position from the bottom edge to the second opening edge is recorded as point A, the area of the first segment spraying process is the arc surface area corresponding to the distance from the bottom edge to the A point, and the area of the second segment spraying process is the arc surface area corresponding to the distance from the A point to the second opening edge. Preferably, the first segment spraying and the second segment spraying each independently comprise at least one segment spraying process. Preferably, in the at least one segment spraying process of the first segment spraying, the moving speed of the spray gun is an eighth speed. Preferably, the eighth speed is 13 mm / s to 16 mm / s. Preferably, in the at least one segment spraying process of the second segment spraying, the moving speed of the spray gun is a ninth speed. Preferably, the ninth speed is 200 mm / s to 300 mm / s.

6. The spray coating method according to any one of claims 1 to 5, characterized in that, The eighth spraying in step (3) is sub-section spraying, which comprises spraying the opposite surfaces of the first open hole first, and then spraying the remaining two opposite surfaces of the metal bond layer; Preferably, the ceramic face layer obtained by the sub-section spraying is steppedly overlapped between regions; Preferably, the tenth speed of the spray gun movement is the same in the eighth spraying in step (3); Preferably, the tenth speed is 500mm / s~600mm / s; Preferably, the step distance of the spray gun is the same in the eighth spraying in step (3); Preferably, the step distance of the spray gun is 4mm~5mm.

7. The spray coating method according to any one of claims 1 to 6, characterized in that, The spraying of the metal bond layer in step (2) is supersonic flame spraying; Preferably, the spraying of the ceramic face layer in step (3) is atmospheric plasma spraying.

8. The spray coating method according to any one of claims 1 to 7, characterized in that, Step (1) further comprises oil removal of the complex profile and multi-open-hole flame tube, and sand blasting treatment of the surface to be sprayed, to obtain a complex profile and multi-open-hole flame tube to be sprayed.

9. The thermal barrier coating of a complex profile and a multi-perforated flame tube, which is obtained by the spraying method according to any one of claims 1 to 8, characterized in that, The thermal barrier coating comprises a metal bond layer and a ceramic face layer on the surface of the metal bond layer, and the metal bond layer is on the inner wall surface of the complex profile and multi-open-hole flame tube.

10. The thermal barrier coating of a complex profile and multi-perforated flame tube of claim 9, wherein, The average thickness of the thermal barrier coating is 0.25mm~0.35mm; Preferably, the thickness deviation of the thermal barrier coating is ≤10% everywhere; Preferably, the average thickness of the metal bond layer is 0.05mm~0.15mm; Preferably, the thickness deviation of the metal bond layer is ≤8.5% everywhere; Preferably, the bonding strength of the metal bond layer is ≥80MPa; Preferably, the porosity of the metal bond layer is ≤0.2%; Preferably, the bonding strength of the ceramic face layer is ≥24MPa; Preferably, the interface contamination of the ceramic face layer is ≤10%.

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