Corrosion-resistant strain-tolerant layer / column composite structure heat insulation coating and preparation method thereof

Abstract

The invention discloses a corrosion-resistant strain-tolerant layer / column composite structure heat insulation coating and a preparation method thereof, and belongs to the technical field of coatings, and the coating sequentially presents a layered structure area, a layer / column composite structure area and a layered structure area in the heat flow direction. The compact layered structure area of the bottom layer of the coating is connected with the matrix, so that the fracture toughness of the coating is enhanced, and the cracking resistance of the coating is improved; the layer / column composite structure area is formed by segmenting a layered structure by longitudinal cracks growing from inside to outside and generated by cooling a preheated coating of a base body, N is larger than or equal to 2 sub ceramic layers, the bonding rate of all the layers is gradually increased in the heat flow direction, and the columnar structure can effectively reduce the cracking driving force, improve the strain capacity of the coating and improve the corrosion resistance of the coating. The layered structure can improve the heat insulation performance of the coating; and the top compact layered structure region can effectively prevent a corrosive medium from entering the coating, so that the corrosion resistance of the coating is improved. Therefore, the corrosion-resistant strain-tolerant layer / column composite structure heat insulation coating designed and prepared by the invention can achieve the collaborative optimization effects of high heat insulation, long service life and corrosion resistance.

Description

Technical Field

[0001] This invention belongs to the field of coating technology, specifically relating to a corrosion-resistant strain-resistant layer / column composite thermal insulation coating and its preparation method. Background Technology

[0002] Thermal barrier coatings (TBCs) are widely used for surface thermal insulation protection of high-temperature metal-based components in high-end equipment such as aero-engines and heavy-duty gas turbines due to their unique structure and performance. The three most important indicators for evaluating TBCs are their insulation temperature, service life, and corrosion resistance: To achieve the ideal insulation temperature, TBCs need to have low thermal conductivity and a certain thickness to insulate heat flow and reduce metal-to-metal contact temperature; to extend the service life of TBCs, they need to remain adhered to the substrate throughout service without detachment, peeling, or cracking; to improve corrosion resistance, TBCs need to have a slow corrosion rate and minimize the penetration of corrosive media into their interior to prevent rapid failure and loss of insulation function.

[0003] The key to achieving high thermal insulation, long lifespan, and corrosion resistance in TBCs lies in their rational design of structure and fabrication process. Heavy-duty gas turbine combustors are a typical component protected by TBCs, generally requiring TBCs with a large thickness (≥1mm), significantly higher than the thickness of TBCs in other components (guide vanes, working blades, etc.) (generally not exceeding 0.8mm). While greater thickness corresponds to higher thermal insulation performance, the cracking driving force within the TBCs also increases significantly with increasing thickness, resulting in a shorter lifespan. Furthermore, the layered structure of TBCs prepared using traditional methods is accompanied by numerous pores and microcracks, weakening the fracture toughness of the TBCs themselves. Therefore, thick TBCs prepared using traditional processes are prone to cracking and detachment, failing to meet the requirements for long lifespan. Introducing longitudinal cracks along the heat flow direction into the ceramic layer can reduce thermal stress and lower the cracking driving force. The existing method for introducing longitudinal cracks in coatings involves reheating the substrate and coating after coating preparation, followed by rapid cooling and shrinkage of one side of the coating. Due to the constraint of the substrate, the coating shrinkage is inhibited, creating stress within the coating. Under this stress, longitudinal cracks are generated from the coating surface and propagate inward. This method has the following significant drawbacks in introducing longitudinal cracks: (1) It inevitably forms longitudinal cracks that penetrate the surface, thus creating a rapid channel for corrosive media to penetrate deep into the coating, causing adverse reactions that lead to coating detachment and damage; (2) It cannot produce longitudinal cracks of great depth because the cracking driving force in the vertical direction is relatively small, which is insufficient to allow the longitudinal cracks to extend to a deeper part of the coating. Summary of the Invention

[0004] This invention provides a corrosion-resistant strain-resistant composite thermal insulation coating and its preparation method. By introducing deep longitudinal cracks that do not penetrate to the top of the coating into a thick, dense-porous-dense structure, the coating can achieve long service life while ensuring high thermal insulation. This is achieved through strain resistance of the deep longitudinal cracks, crack resistance of the toughening layer, and corrosion resistance of the top dense layer, thus meeting the service requirements of advanced coatings.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: In a first aspect, the present invention provides a corrosion-resistant strain-resistant layer / column composite thermal insulation coating, comprising a ceramic thermal insulation layer and a metal bonding layer sequentially disposed on a substrate along the heat flow direction; the ceramic thermal insulation layer sequentially comprises a first layered structure region, a layer / column composite structure region, and a second layered structure region along the heat flow direction; the interlayer bonding rate of the first layered structure region and the second layered structure region is >60%; the layer / column composite structure region is divided into multiple columns by longitudinal cracks parallel to the heat flow direction, the ratio of the average width of the column perpendicular to the heat flow direction to the thickness of the layer / column composite structure region is 0.5~3, and a single column is composed of stacked layers with an interlayer bonding rate of 20%~60%.

[0006] Furthermore, the layered structure region is provided with N sub-layers along the heat flow direction, where N is an integer ≥2, and the interlayer bonding rate of each sub-layer gradually increases along the heat flow direction.

[0007] Furthermore, the thickness of the first layered structure region accounts for 5% to 25% of the thickness of the ceramic insulation layer, and the thickness of the second layered structure region accounts for 10% to 15% of the thickness of the ceramic insulation layer.

[0008] Furthermore, the average length of the longitudinal crack is 60%-85% of the thickness of the thermal insulation coating of the corrosion-resistant strain-resistant layer / column composite structure.

[0009] Furthermore, the ceramic insulation layer is selected with an intrinsic thermal conductivity ≤2.5W / m·K and a fracture toughness ≥2MPa·m at temperatures ranging from 200℃ to 1600℃. 0.5 Ceramic materials.

[0010] Secondly, the present invention provides a method for preparing a corrosion-resistant strain-resistant layer / column composite thermal insulation coating, comprising the following steps: Step 1: Prepare a metal bonding layer on the upper surface of the substrate using a thermal spraying method; Step 2: Prepare a ceramic heat insulation layer with a thickness of 1mm to 2mm on the metal bonding layer using a thermal spraying method; Step 2 includes the following steps: Step 2.1: Preheat the substrate containing the deposited metal binder layer to 600℃~700℃ and keep it at that temperature; then, spray multiple coats onto the metal binder layer to deposit the second layered structure region, with a thickness of 10%~15% of the total thickness of the ceramic insulation layer; during the deposition process under the preheated substrate conditions, immediately cool the deposited coating after each coat. Step 2.2: Sequentially reduce the preheating temperature of the Nth sublayer to the 1st sublayer of the deposition layer / column composite structure region, wherein the preheating temperature of the Nth sublayer is <600℃ and the preheating temperature of the 1st sublayer is ≤150℃, and the particle size of the powder used for deposition is 10-75μm; during the deposition process, immediately cool the deposited coating after each spraying. Step 2.3: Preheat the substrate to 600°C again, deposit the first layered structure region, and use powder with a particle size of 10-45μm for deposition. After deposition, allow the first layered structure region to cool naturally to room temperature.

[0011] Furthermore, in step 1, a metal bonding layer is prepared on the upper surface of the substrate by means of atmospheric plasma spraying with deoxidation treatment, supersonic flame spraying, low-pressure plasma spraying or cold spraying.

[0012] Furthermore, in step 2, an atmospheric plasma spraying method is used to prepare a ceramic heat insulation layer on the metal bonding layer.

[0013] Furthermore, in steps 2.1 to 2.2, the cooling gas is nitrogen or air, and the cooling gas pressure is 0.4-0.8 MPa.

[0014] Furthermore, in step 2.2, the preheating temperature of the substrate is reduced by 100-250℃ each time.

[0015] Compared with the prior art, the present invention has at least the following beneficial technical effects: This invention discloses a corrosion-resistant strain-resistant layer / column composite thermal insulation coating and its preparation method. To achieve high thermal insulation and crack resistance, deep longitudinal cracks are introduced into the dense-porous-dense gradient structure coating, extending into the bottom toughening zone and not penetrating the top dense zone. The average length of the longitudinal cracks is between 60% and 85% of the total thickness of the layer / column composite thermal insulation coating. On the one hand, the coating prepared by plasma spraying has a typical layered structure with numerous pores and microcracks, effectively reducing the thermal conductivity of the coating and minimizing heat transfer, thus providing thermal insulation. On the other hand, the deep longitudinal cracks effectively alleviate the high stress caused by the large thickness, reducing the cracking driving force and improving the coating's strain-resistant capacity. Furthermore, a dense, toughened ceramic layer—the second layered structure region—is designed at the bottom of the ceramic insulation layer (with a gradient transition between the porous ceramic layer and the dense, toughened ceramic layer to avoid abrupt structural changes). This improves crack resistance and fracture toughness, thereby enhancing the coating's crack resistance and achieving a longer service life. Simultaneously, compared to traditional coatings where longitudinal cracks penetrate the top, this coating features a dense, crack-free first layered structure region on the top of the ceramic layer, with a thickness of 5%-25% of the total ceramic layer thickness. This dense structure isolates the coating from corrosive media, resulting in superior corrosion resistance.

[0016] The method proposed in this invention generates longitudinal cracks in situ during the spraying process, specifically longitudinal cracks generated within the ceramic insulation layer 3. Then, during coating formation, online cooling with cooling gas allows these longitudinal cracks to extend from the bottom to the top of the layer / column composite structure region. This results in longitudinal cracks that, while not penetrating to the top of the ceramic insulation layer, possess considerable depth, achieving corrosion resistance and a long service life. Firstly, this method of spraying one layer of coating followed by using cooling gas to propagate a layer of cracks results in deep longitudinal cracks with good perpendicularity, leading to a stronger crack resistance in the coating. Secondly, the coating preparation process is based on a low-cost and mature plasma spraying technology, making it highly feasible and quickly applicable to engineering projects. Thirdly, because the depth of the longitudinal cracks is controllable, the first layered structure region remains dense and free of longitudinal cracks, preventing corrosive media from penetrating the ceramic insulation layer along the longitudinal cracks and inducing corrosion failure, thus enhancing the coating's corrosion resistance. Attached Figure Description

[0017] Figure 1 A schematic diagram of a corrosion-resistant compressive strain layer / column composite thermal insulation coating prepared using plasma spraying technology; Figure 2 This is a schematic diagram of the cross-section of the thermal insulation coating of the corrosion-resistant strain-resistant layer / column composite structure; Figure 3 for Figure 2 Cross-sectional views of AA and BB in the middle; Figure 4 This is a schematic diagram illustrating the formation of longitudinal cracks from the inside out using this method; Figure 5 The image shows the cross-sectional morphology of the coatings containing longitudinal cracks prepared using conventional methods. Figure 6 The image shows the cross-sectional morphology of the coating containing longitudinal cracks prepared in Example 1 of this invention. Figure 7 The image shows the cross-sectional morphology of the coating containing longitudinal cracks prepared in Example 2 of this invention. Figure 8 The image shows the cross-sectional morphology of the coating containing longitudinal cracks prepared in Example 3 of this invention. Figure 9 The image shows the cross-sectional morphology of the coating containing longitudinal cracks prepared in Example 4 of this invention. Figure 10 The image shows the cross-sectional morphology and elemental distribution of the comparative coatings containing longitudinal cracks prepared using conventional methods after corrosion. Figure 11 The image shows the cross-sectional morphology of the coating containing longitudinal cracks after corrosion, prepared by the method of Example 2 of this invention. Figure 12 A comparison of the thermal cycling lifetime of coatings prepared by conventional methods and embodiments of the present invention.

[0018] In the attached diagram: 1. Matrix, 2. Metal bonding layer, 3. Ceramic insulation layer, 3-1. First layered structure region, 3-2. Layer / column composite structure region, 3-3. Second layered structure region, 4. Sheet unit, 5. Longitudinal crack, 6. Interlayer micropores, 7. Intralayer microcracks, 8. Molten powder, 9. Cooling air gun, 10. Spray gun, 11. Cooling gas. Detailed Implementation

[0019] To make the objectives and technical solutions of this invention clearer and easier to understand, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. The specific embodiments described herein are for illustrative purposes only and are not intended to limit the invention.

[0020] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more. In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0021] Conventional coatings achieve crack resistance and high thermal insulation through a structure that is dense at the bottom (high interlayer bonding rate, crack resistance) and porous at the top (low interlayer bonding rate, high thermal insulation). However, when the coating thickness increases to more than 1 mm, the bottom toughening zone alone cannot effectively alleviate the high stress caused by the large thickness. In this case, longitudinal cracks are introduced into the coating to relieve stress, and the longitudinal cracks work in conjunction with the bottom toughening zone to achieve long service life. However, the introduction of longitudinal cracks provides a rapid channel for corrosive media to enter the coating, severely affecting the coating's corrosion resistance. This invention improves the coating's corrosion resistance by spraying a dense first layered structure zone without longitudinal cracks onto the top of the coating to isolate the corrosive media.

[0022] A corrosion-resistant strain-resistant layer / column composite thermal insulation coating is characterized by comprising a metal bonding layer 2 and a ceramic thermal insulation layer 3 located on the metal bonding layer 2. The total thickness of the ceramic thermal insulation layer 3 is 1000~2000μm, and along the heat flow direction, it sequentially presents a first layered structure region 3-1, a layer / column composite structure region 3-2, and a second layered structure region 3-3, wherein the thickness of the first layered structure region 3-1 accounts for 5%~25% of the thickness of the ceramic thermal insulation layer 3 (if the thickness is too small, it cannot resist corrosion; if the thickness is too large, it reduces the thermal cycle life), and the thickness of the second layered structure region 3-3 accounts for 10%~15% of the thickness of the ceramic thermal insulation layer 3. Both the first layered structure region 3-1 and the second layered structure region 3-3 are composed of many stacked lamellar units, with an interlayer bonding rate >60%, resulting in a dense structure. The layer / column composite structure region 3-2 has multiple longitudinal cracks 5 distributed parallel to the heat flow direction. These longitudinal cracks 5 divide the layer / column composite structure region 3-2 into multiple columns. The ratio of the average width of the column perpendicular to the heat flow direction to the thickness of the layer / column composite structure region 3-2 is 0.5~3, and the width d is as follows: Figure 2 As shown, a single column is composed of stacked layers with a bonding rate of 20% to 60%, resulting in a porous structure. The pores include interlayer micropores 6 formed due to incomplete bonding and perpendicular to the heat flow direction, while the rapid cooling and shrinkage of individual layers causes cracking, forming intralayer microcracks 7 parallel to the heat flow direction.

[0023] In the layer / column composite structure region 3-2, 1-N sub-layers are arranged along the heat flow direction, where N≥2, and the interlayer bonding rate gradually increases from the 1st to the Nth sub-layer, showing a gradient change. The first layered structure region 3-1 is formed by stacking first layered units 4-1 perpendicular to the heat flow direction, the layer / column composite structure region 3-2 is formed by stacking second layered units 4-2 perpendicular to the heat flow direction, and the second layered structure region 3-3 is formed by stacking third layered units 4-3 perpendicular to the heat flow direction.

[0024] In this structure, the lamellar units 4-1 of the layered structure region 3-1 have dimensions of 2μm~20μm perpendicular to the heat flow direction and 0.5μm~5μm along the heat flow direction; the lamellar units 4-2 of the layer / column composite structure region 3-2 have dimensions of 2μm~30μm perpendicular to the heat flow direction and 0.5μm~5μm along the heat flow direction; and the lamellar units 4-3 of the layered structure region 3-3 have dimensions of 2μm~20μm perpendicular to the heat flow direction and 0.5μm~5μm along the heat flow direction. The intralayer microcracks 7 have dimensions of 0.0001μm~1μm perpendicular to the heat flow direction and 0.1μm~10μm parallel to the heat flow direction.

[0025] A method for preparing a corrosion-resistant strain-resistant composite layer / column insulation coating includes the following steps: Step 1: Prepare a 100-250 μm thick metal bonding layer 2 on the upper surface of substrate 1 using a thermal spraying method. Substrate 1 is a metal substrate. Step 2: Prepare a ceramic heat insulation layer 3 on the metal bonding layer 2 by thermal spraying. The total thickness of the ceramic heat insulation layer 3 is 1-2 mm. Step 2 includes the following steps: Step 2.1: Preheat the substrate 1 with the deposited metal bonding layer 2 to 600℃~700℃ and maintain the temperature; then, deposit ceramic powder on the metal bonding layer 2 to form a second layered structure region 3-3. The particle size of the ceramic powder used for deposition is 10-45μm, and the thickness of the second layered structure region 3-3 is 10%~15% of the total thickness of the ceramic heat insulation layer 3; during the deposition process under the preheated substrate conditions, immediately cool the deposited part after each spraying (the thickness of each deposition is about 10μm-20μm), and the cooling gas 11 is nitrogen or air with a gas pressure of 0.4-0.8MPa; Step 2.2: Sequentially decrease the preheating temperature and deposit the Nth to the 1st sublayer of the layer / column composite structure region 3-2 on the second layered structure region 3-3, with each temperature decrease being 100-250℃. The preheating temperature of the 3-2-N sublayer is <600℃, and the preheating temperature of the 3-2-1 sublayer is ≤150℃. The powder particle size is 10-75μm. During the deposition process, the deposited coating is cooled immediately after each spraying. The cooling gas 11 is nitrogen or air, and the cooling gas pressure is 0.4-0.8MPa. Step 2.3: Preheat the substrate to 600°C again, deposit ceramic powder to form the first layered structure region 3-1. The particle size of the ceramic powder used for deposition is 10-45μm. After deposition, the first layered structure region 3-1 is allowed to cool naturally to room temperature without the use of cooling gas.

[0026] In step 1, a metal bonding layer 2 is prepared on the upper surface of the substrate by means of atmospheric plasma spraying with deoxidation treatment, supersonic flame spraying, low-pressure plasma spraying or cold spraying.

[0027] In step 2, a ceramic heat insulation layer 3 is prepared on the metal bonding layer 2 using atmospheric plasma spraying.

[0028] In step 2, the intrinsic thermal conductivity is ≤2.5W / m·K and the fracture toughness is ≥2MPa·m at temperatures ranging from 200℃ to 1600℃. 0.5 The ceramic material is thermally sprayed onto the metal bonding layer 2 to prepare the ceramic insulation layer 3. The ceramic material can be yttrium-stabilized zirconium oxide (YSZ), rare earth-stabilized zirconium oxide (RSZ), rare earth zirconates, rare earth tantalates, titanates, alumina-based ceramics, or high-entropy ceramics.

[0029] Example 1 Reference Figures 1 to 4 A method for preparing a corrosion-resistant strain-resistant layer / column composite thermal insulation coating includes the following steps: Step 1: Select a cylindrical high-temperature alloy substrate 1 with a diameter of 25.4 mm and a height of 3 mm. Use a supersonic flame spraying process to prepare a 250 μm thick metal bonding layer 2 on the upper surface of the substrate 1. The material of the metal bonding layer 2 is spherical NiCoCrAlTaY powder with a particle size of ~37 μm. Alternatively, in this step, atmospheric plasma spraying with deoxidation treatment, cold spraying, vacuum plasma spraying, or low-pressure plasma spraying can also be used to prepare the metal bonding layer 2 on the substrate 1.

[0030] Step 2.1: Preheat the substrate to 600 ℃. Use 10-45 μm yttrium-stabilized zirconia powder to prepare a dense second layered structure region 3-3 with a thickness of approximately 200 μm on the surface of the bonding layer 2 using an atmospheric plasma spraying process. Control the spraying parameters to ensure an interlayer bonding rate >60%, achieving crack resistance. Under the preheated substrate 1 condition, during the deposition process, immediately cool the deposited coating after each spraying layer to create a large temperature difference between the substrate 1 and the second layered structure region 3-3, promoting the formation of longitudinal crack initiation sites on the upper surface of the second layered structure region 3-3. The spraying parameters include: spraying power of 42 kW, main argon gas of 50 L / min, auxiliary hydrogen gas of 7 L / min, spraying distance of 80 mm, and gun travel speed of 400 mm / s; the cooling gas is air at a pressure of 0.6 MPa.

[0031] Step 2.2: Preheat the substrate to 500 ℃. Use 10-45 μm yttrium-stabilized zirconia powder to further prepare the third sublayer 3-2-3 of the layer / pillar composite structure region 3-2 on the surface of the second layered structure region 3-3 using atmospheric plasma spraying, with a thickness of 300 μm. Control the spraying parameters to ensure that the interlamellar bonding rate of the third sublayer 3-2-3 is between 50% and 60%. Under the preheated substrate conditions, during the deposition process, immediately cool the deposited coating after each spraying to create a large temperature difference between the substrate and the third sublayer 3-2-3, promoting the propagation of longitudinal cracks within the third sublayer 3-2-3 to the surface. The spraying parameters include: spraying power of 42 kW, main argon gas of 50 L / min, auxiliary hydrogen gas of 7 L / min, spraying distance of 80 mm, and gun speed of 400 mm / s; the cooling gas is nitrogen or air at a pressure of 0.6 MPa.

[0032] Step 2.3: Preheat the substrate to 400 ℃. Use 45-75 μm yttrium-stabilized zirconia powder to prepare the second sublayer 3-2-2 on the surface of the third sublayer 3-2-3 in the layer / pillar composite zone 3-2 using atmospheric plasma spraying, with a thickness of 500 μm. By controlling the spraying parameters, ensure that the interlaminar bonding rate of the second sublayer 3-2-2 is between 40% and 50%, exhibiting a porous structure and achieving high thermal insulation. Under the preheated substrate conditions, during the deposition process, immediately cool the deposited coating after each spraying to create a temperature difference between the substrate and the second sublayer 3-2-2, promoting the continued propagation of longitudinal cracks within the second sublayer 3-2-2 to the surface. The spraying parameters include: spraying power of 42 kW, main argon gas of 50 L / min, auxiliary hydrogen gas of 7 L / min, spraying distance of 80 mm, and gun speed of 500 mm / s; the cooling gas is air at a pressure of 0.6 MPa.

[0033] Step 2.4: Lower the preheating temperature and preheat the substrate to 150℃. Select 45-75 μm yttrium-stabilized zirconia powder and use atmospheric plasma spraying to prepare a 900 μm thick first sublayer 3-2-1 with a more porous structure on the surface of the second sublayer 3-2-2 in the layer / pillar composite zone 3-2. By controlling the spraying parameters, ensure that the interlaminar bonding rate of the first sublayer 3-2-1 is between 20% and 40% to achieve high thermal insulation. Under the preheated substrate conditions, during the deposition process, immediately cool the deposited coating after each spraying to promote the continued propagation of longitudinal cracks inside the first sublayer 3-2-1 to the surface. The spraying parameters include: spraying power of 42 kW, main argon gas of 50 L / min, auxiliary hydrogen gas of 7 L / min, spraying distance of 100 mm, and gun speed of 500 mm / s; the cooling gas is air with a pressure of 0.6 MPa. Step 2.5: Preheat the substrate again to 600℃. Use 10-45μm yttrium-stabilized zirconia powder to prepare a first layered structure region 3-1 with a thickness of 100 μm and a dense structure on the surface of the layer / column composite region 3-2 using atmospheric plasma spraying. Control the spraying parameters to ensure an interlayer bonding rate >60%. After spraying, allow the coating to cool naturally to room temperature without using cooling gas to reduce the driving force for longitudinal cracking, resulting in a dense structure without longitudinal cracks in this region, thereby isolating the corrosive medium and achieving corrosion resistance. The spraying parameters include: spraying power of 42kW, main argon gas of 50 L / min, auxiliary hydrogen gas of 7 L / min, spraying distance of 80 mm, and gun travel speed of 400 mm / s.

[0034] Based on the above steps, a schematic diagram of the prepared corrosion-resistant strain-resistant layer / column composite thermal insulation coating structure is shown below. Figure 2As shown. The corrosion-resistant strain-resistant layer / column composite thermal insulation coating includes a metal bonding layer 2 and a ceramic thermal insulation layer 3 located on the metal bonding layer. The total thickness of the ceramic thermal insulation layer 3 is 2000 μm. The ceramic thermal insulation layer 3 sequentially presents a first layered structure region 3-1, a layer / column composite structure region 3-2, and a second layered structure region 3-3 in the direction parallel to the heat flow. The layer / column composite structure region 3-2 is divided into multiple columns by longitudinal cracks 5 parallel to the heat flow direction. The ratio of the average width of the column perpendicular to the heat flow direction to the thickness of the layer / column composite structure region 3-2 is 0.7. The average length of the longitudinal cracks 5 accounts for 85% of the total thickness of the ceramic thermal insulation layer 3. Figure 6 As shown.

[0035] Example 2 Reference Figures 1 to 4 A method for preparing a corrosion-resistant strain-resistant layer / column composite thermal insulation coating includes the following steps: Step 1: Select a cylindrical high-temperature alloy substrate 1 with a diameter of 25.4 mm and a height of 3 mm. Use a supersonic flame spraying process to prepare a 250 μm thick metal bonding layer 2 on the upper surface of the substrate 1. The material of the metal bonding layer 2 is spherical NiCoCrAlTaY powder with a particle size of ~37 μm. Alternatively, in this step, atmospheric plasma spraying with deoxidation treatment, cold spraying, vacuum plasma spraying, or low-pressure plasma spraying can also be used to prepare the metal bonding layer 2 on the substrate 1.

[0036] Step 2.1: Preheat the substrate to 600 ℃. Use 10-45 μm yttrium-stabilized zirconia powder to prepare a dense second layered structure region 3-3 with a thickness of approximately 200 μm on the surface of the bonding layer 2 using an atmospheric plasma spraying process. Control the spraying parameters to ensure an interlayer bonding rate >60%, achieving crack resistance. Under the preheated substrate 1 condition, during the deposition process, immediately cool the deposited coating after each spraying layer to create a large temperature difference between the substrate 1 and the second layered structure region 3-3, promoting the formation of longitudinal crack initiation sites on the upper surface of the second layered structure region 3-3. The spraying parameters include: spraying power of 42 kW, main argon gas of 50 L / min, auxiliary hydrogen gas of 7 L / min, spraying distance of 80 mm, and gun travel speed of 400 mm / s; the cooling gas is air at a pressure of 0.6 MPa.

[0037] Step 2.2: Preheat the substrate to 500 ℃. Use 10-45 μm yttrium-stabilized zirconia powder to further prepare the third sublayer 3-2-3 of the layer / column composite structure region 3-2 on the surface of the second layered structure region 3-3 using atmospheric plasma spraying, with a thickness of 300 μm. Control the spraying parameters to ensure the interlayer bonding rate is between 50-60%. Under the preheated substrate conditions, during deposition, immediately cool the deposited coating after each spraying to create a large temperature difference between the substrate and the third sublayer 3-2-3, promoting the propagation of longitudinal cracks within the third sublayer 3-2-3 to the surface. Spraying parameters include: spraying power of 42 kW, main argon gas of 50 L / min, auxiliary hydrogen gas of 7 L / min, spraying distance of 80 mm, and gun speed of 400 mm / s; the cooling gas is nitrogen or air at a pressure of 0.6 MPa.

[0038] Step 2.3: Preheat the substrate to 400 ℃. Use 45-75 μm yttrium-stabilized zirconia powder to prepare a second sublayer 3-2-2 on the surface of the third sublayer 3-2-3 in the layer / pillar composite zone 3-2 using atmospheric plasma spraying, with a thickness of 500 μm. By controlling the spraying parameters, ensure that the interlayer bonding rate is between 40% and 50%, resulting in a porous structure and high thermal insulation. Under the preheated substrate conditions, during the deposition process, immediately cool the deposited coating after each spraying to create a temperature difference between the substrate and the second sublayer 3-2-2, promoting the continued propagation of longitudinal cracks within the second sublayer 3-2-2 to the surface. The spraying parameters include: spraying power of 42 kW, main argon gas of 50 L / min, auxiliary hydrogen gas of 7 L / min, spraying distance of 80 mm, and gun speed of 500 mm / s; the cooling gas is air at a pressure of 0.6 MPa.

[0039] Step 2.4: Lower the preheating temperature to 150℃. Use 45-75 μm yttrium-stabilized zirconia powder to further prepare a 700 μm thick, more porous first sublayer 3-2-1 on the surface of the second sublayer 3-2-2 in the layer / pillar composite zone 3-2 using atmospheric plasma spraying. Control the spraying parameters to ensure the interlayer bonding rate is between 20% and 40%, achieving high thermal insulation. Under preheated substrate conditions, during deposition, immediately cool the deposited coating after each coat to promote the continued propagation of longitudinal cracks within the first sublayer 3-2-1 to the surface. Spraying parameters include: spraying power of 42 kW, main argon gas of 50 L / min, auxiliary hydrogen gas of 7 L / min, spraying distance of 100 mm, and gun speed of 500 mm / s; cooling gas is air at a pressure of 0.6 MPa. Step 2.5: Preheat the substrate again to 600℃. Use 10-45μm yttrium-stabilized zirconia powder to prepare a first layered structure region 3-1 with a thickness of 300μm and a dense structure on the surface of the layer / column composite region 3-2 using atmospheric plasma spraying. Control the spraying parameters to ensure an interlayer bonding rate >60%. After spraying, allow the coating to cool naturally to room temperature without using cooling gas to reduce the driving force for longitudinal cracking, thus forming a dense structure without longitudinal cracks in this region, thereby isolating the corrosive medium and achieving corrosion resistance. The spraying parameters include: spraying power of 42kW, main argon gas of 50 L / min, auxiliary hydrogen gas of 7 L / min, spraying distance of 80 mm, and gun speed of 400 mm / s.

[0040] Based on the above steps, a schematic diagram of the prepared corrosion-resistant strain-resistant layer / column composite thermal insulation coating structure is shown below. Figure 2 As shown, it includes a metal bonding layer 2 and a ceramic insulation layer 3 located on the metal bonding layer. The total thickness of the ceramic insulation layer 3 is 2000 μm. The ceramic insulation layer 3 sequentially presents a first layered structure region 3-1, a layer / column composite structure region 3-2, and a second layered structure region 3-3 in the direction parallel to the heat flow. The layer / column composite structure region 3-2 is divided into multiple columns by longitudinal cracks 5 parallel to the heat flow direction. The ratio of the average width of the column perpendicular to the heat flow direction to the thickness of the layer / column composite structure region 3-2 is 0.6. The average length of the longitudinal cracks 5 accounts for 70% of the total thickness of the ceramic insulation layer 3. Figure 7 As shown.

[0041] Example 3 The difference between this embodiment and Embodiment 1 is as follows: In steps 2.1-2.4, the cooling gas pressure is 0.5 MPa; in step 2.4, the thickness of the first sublayer 3-2-1 of the layer / column composite structure region 3-2 is 500 μm; in step 2.5, the thickness of the first layered structure region 3-1 is 500 μm; the resulting coating morphology is as follows. Figure 8 As shown.

[0042] Based on the above steps, a schematic diagram of the prepared corrosion-resistant strain-resistant layer / column composite thermal insulation coating structure is shown below. Figure 2 As shown, it includes a metal bonding layer 2 and a ceramic insulation layer 3 located on the metal bonding layer. The total thickness of the ceramic insulation layer 3 is 2000 μm. The ceramic insulation layer 3 sequentially presents a first layered structure region 3-1, a layer / column composite structure region 3-2, and a second layered structure region 3-3 in the direction parallel to the heat flow. The layer / column composite structure region 3-2 is divided into multiple columns by longitudinal cracks 5 parallel to the heat flow direction. The ratio of the average width of the column perpendicular to the heat flow direction to the thickness of the layer / column composite structure region 3-2 is 0.9. The average length of the longitudinal cracks 5 accounts for 60% of the total thickness of the ceramic insulation layer 3.

[0043] Example 4 The difference between this embodiment and Embodiment 1 is that in step 2, the total thickness of the ceramic heat insulation layer 3 is 1000 μm, wherein the thickness of the first layered structure region 3-1 is 200 μm, the thickness of the layer / column composite structure region 3-2 is 700 μm, and the thickness of the second layered structure region 3-3 is 100 μm; the cooling gas pressure is 0.4 MPa. The resulting coating morphology is as follows. Figure 9 As shown, the layer / column composite structure region 3-2 is divided into multiple columns by longitudinal cracks 5 parallel to the heat flow direction. The average width of the column along the direction perpendicular to the heat flow direction is 2 times the thickness of the layer / column composite structure region 3-2. The average length of the longitudinal cracks 5 accounts for 70% of the total thickness of the ceramic insulation layer 3.

[0044] Example 5 The difference between this embodiment and Embodiment 1 is as follows: In step 2, the total thickness of the ceramic insulation layer 3 is 1500 μm, wherein the thickness of the first layered structure region 3-1 is 200 μm, the thickness of the layer / column composite structure region 3-2 is 1000 μm, and the thickness of the second layered structure region 3-3 is 300 μm; in step 2.1, the substrate preheating temperature is 650℃. The layer / column composite structure region 3-2 is divided into multiple columns by longitudinal cracks 5 parallel to the heat flow direction. The ratio of the average width of the column perpendicular to the heat flow direction to the thickness of the layer / column composite structure region 3-2 is 0.8, and the average length of the longitudinal cracks 5 accounts for 67% of the total thickness of the ceramic insulation layer 3.

[0045] Example 6 The difference between this embodiment and Embodiment 1 is that in step 2.1, the substrate preheating temperature is 700℃ and the cooling gas pressure is 0.8MPa; in steps 2.1-2.4, the temperature is reduced by 200℃ each time. The layer / column composite structure region 3-2 is divided into multiple columns by longitudinal cracks 5 parallel to the heat flow direction. The ratio of the average width of the column perpendicular to the heat flow direction to the thickness of the layer / column composite structure region 3-2 is 0.5, and the average length of the longitudinal cracks 5 accounts for 85% of the total thickness of the ceramic insulation layer 3.

[0046] Example 7 The difference between this embodiment and Embodiment 1 is that in step 1, the thickness of the deposited metal bonding layer is 100 μm, and the method for depositing the metal bonding layer 2 is atmospheric plasma spraying with deoxidation treatment, using diamond (C) as the deoxidizer. The layer / column composite structure region 3-2 is divided into multiple columns by longitudinal cracks 5 parallel to the heat flow direction. The ratio of the average width of the column perpendicular to the heat flow direction to the thickness of the layer / column composite structure region 3-2 is 0.7, and the average length of the longitudinal cracks 5 accounts for 85% of the total thickness of the ceramic insulation layer 3.

[0047] Reference Figure 5The figures show the cross-sectional morphology of a comparative coating containing longitudinal cracks but lacking a top dense layer, prepared using conventional methods. Specifically, during coating preparation, the cooling gas method proposed in this invention was not used. After preparation, the coating and substrate were simultaneously heated to >600°C, and then the coating was rapidly cooled using cooling gas with a temperature difference ≥400°C. This provided the cracking driving force, causing longitudinal cracks to originate from the surface and propagate inwards. The thickness of the layered structure region at the bottom, free of longitudinal cracks, is approximately 800 μm.

[0048] Reference Figure 6 The image shows the cross-sectional morphology of the coating containing longitudinal cracks and a top dense layer prepared according to Example 1 of the present invention. The layer / column composite structure region 3-2 is divided into multiple columns by longitudinal cracks 5 parallel to the heat flow direction. The ratio of the average width of the column perpendicular to the heat flow direction to the thickness of the layer / column composite structure region 3-2 is 0.7. The average length of the longitudinal cracks 5 accounts for 85% of the total thickness of the ceramic heat insulation layer 3.

[0049] Reference Figure 7 The image shows the cross-sectional morphology of the coating containing longitudinal cracks and a top dense layer prepared according to Example 2 of the present invention. The layer / column composite structure region 3-2 is divided into multiple columns by longitudinal cracks 5 parallel to the heat flow direction. The ratio of the average width of the column perpendicular to the heat flow direction to the thickness of the layer / column composite structure region 3-2 is 0.6. The average length of the longitudinal cracks 5 accounts for 70% of the total thickness of the ceramic heat insulation layer 3.

[0050] Reference Figure 8 The image shows the cross-sectional morphology of the coating containing longitudinal cracks and a top dense layer prepared according to Example 3 of the present invention. The layer / column composite structure region 3-2 is divided into multiple columns by longitudinal cracks 5 parallel to the heat flow direction. The ratio of the average width of the column perpendicular to the heat flow direction to the thickness of the layer / column composite structure region 3-2 is 0.9. The average length of the longitudinal cracks 5 accounts for 60% of the total thickness of the ceramic heat insulation layer 3.

[0051] Reference Figure 9 The image shows the cross-sectional morphology of the coating containing longitudinal cracks and a top dense layer prepared according to Example 4 of the present invention. The layer / column composite structure region 3-2 is divided into multiple columns by longitudinal cracks 5 parallel to the heat flow direction. The ratio of the average width of the column perpendicular to the heat flow direction to the thickness of the layer / column composite structure region 3-2 is 2. The average length of the longitudinal cracks 5 accounts for 70% of the total thickness of the ceramic heat insulation layer 3.

[0052] Reference Figure 10 The images show the cross-sectional morphology and elemental distribution of a control group coating containing longitudinal cracks and lacking a top dense layer, prepared using conventional methods, after corrosion. The corrosion test conditions included: the corrosive medium was calcium magnesium aluminum silicate (CMAS) molten salt, and the salt application rate was 30 mg / cm³. 2The corrosion temperature was 1250℃, and the corrosion time was 10 hours. It can be seen that the corrosion depth after 10 hours was approximately 120 μm, indicating a significant corrosion depth and severe damage. The elemental (Si) distribution map shows that the corrosive medium had penetrated into longitudinal cracks. This indicates that the coating prepared by conventional methods does not possess corrosion-resistant properties.

[0053] Reference Figure 11 The image shows the cross-sectional morphology of the coating containing longitudinal crack 5 and the first layered structure region 3-1 prepared according to Example 2 of this invention after corrosion. The corrosion test conditions included: the corrosive medium was calcium magnesium aluminum silicate (CMAS) molten salt, and the salt coating amount was 30 mg / cm³. 2 The corrosion temperature was 1250℃, and the corrosion time was 10h and 20h. It can be seen that the corrosion depth after 10 hours was approximately 60μm, and the corrosion depth after 20 hours was approximately 80μm, indicating a relatively small corrosion depth and mild corrosion damage; moreover, the corrosive medium did not penetrate the longitudinal crack 5. This indicates that the first layered structure region 3-1 has good corrosion resistance, and the coating exhibits corrosion resistance advantages. Under the same material and test conditions, the corrosion depth is only related to the microstructure of the coating. The coatings prepared using other embodiments of this invention all have a similar first layered structure region 3-1 in microstructure; therefore, the coatings prepared using other embodiments of this invention all have corrosion resistance advantages.

[0054] Reference Figure 12 To test the coating's lifespan using isothermal thermal cycling experiments, one thermal cycle consisted of heating from room temperature to 1050°C within 2 minutes, holding at that temperature for 50 minutes, and cooling down to below 200°C for 10 minutes. The average lifespan of the coating with longitudinal cracks prepared using conventional methods in the control group was 73 cycles; the average lifespan of the coating prepared using Example 1 of this invention was 216 cycles, three times that of the coating with longitudinal cracks prepared using conventional methods; the average lifespan of the coating prepared using Example 2 of this invention was 188 cycles, more than twice that of the coating with longitudinal cracks prepared using conventional methods; and the average lifespan of the coating prepared using Example 3 of this invention was 95 cycles, also significantly higher than the coating with longitudinal cracks prepared using conventional methods. Therefore, the coating prepared by this invention exhibits a superior service life due to its compressive strain.

[0055] The above content is only for illustrating the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made to the technical solution based on the technical concept proposed in this invention shall fall within the scope of protection of the claims of this invention.

Claims

1. A corrosion-resistant strain-resistant layer / column composite thermal insulation coating, characterized in that, The material includes a ceramic heat insulation layer (3) and a metal bonding layer (2) sequentially disposed on a substrate (1) along the heat flow direction; the ceramic heat insulation layer (3) sequentially includes a first layered structure region (3-1), a layer / column composite structure region (3-2) and a second layered structure region (3-3) along the heat flow direction; the interlayer bonding rate of the first layered structure region (3-1) and the second layered structure region (3-3) is >60%; the layer / column composite structure region (3-2) is divided into multiple columns by longitudinal cracks (5) parallel to the heat flow direction, the ratio of the average width of the column perpendicular to the heat flow direction to the thickness of the layer / column composite structure region (3-2) is 0.5~3, and a single column is composed of stacked layers with a layer bonding rate of 20%~60%.

2. The corrosion-resistant strain-resistant layer / column composite thermal insulation coating according to claim 1, characterized in that, The layered structure region (3-2) is provided with N sub-layers along the heat flow direction, where N is an integer ≥2, and the interlayer bonding rate of each sub-layer gradually increases along the heat flow direction.

3. The corrosion-resistant strain-resistant layer / column composite thermal insulation coating according to claim 1, characterized in that, The thickness of the first layered structure region (3-1) accounts for 5% to 25% of the thickness of the ceramic insulation layer (3), and the thickness of the second layered structure region (3-3) accounts for 10% to 15% of the thickness of the ceramic insulation layer (3).

4. The corrosion-resistant strain-resistant layer / column composite thermal insulation coating according to claim 1, characterized in that, The average length of the longitudinal crack is 60%-85% of the thickness of the thermal insulation coating of the corrosion-resistant strain-resistant layer / column composite structure.

5. The corrosion-resistant strain-resistant layer / column composite thermal insulation coating according to claim 1, characterized in that, The ceramic insulation layer (3) is selected with an intrinsic thermal conductivity ≤2.5W / m·K and a fracture toughness ≥2MPa·m at 200℃~1600℃. 0.5 Ceramic materials.

6. The method for preparing a corrosion-resistant strain-resistant layer / column composite thermal insulation coating according to claim 1, characterized in that, Includes the following steps: Step 1: Prepare a metal bonding layer (2) on the upper surface of the substrate (1) by thermal spraying. Step 2: Prepare a ceramic heat insulation layer (3) on the metal bonding layer (2) by thermal spraying, with a thickness of 1mm ~ 2mm; Step 2 includes the following steps: Step 2.1: Preheat the substrate (1) containing the deposited metal bonding layer (2) to 600℃~700℃ and keep it warm; then, spray multiple times on the metal bonding layer (2) to deposit the second layered structure region (3-3), the thickness of which is 10%~15% of the total thickness of the ceramic insulation layer (3); during the deposition process under the preheated substrate conditions, immediately cool the deposited coating after each spraying. Step 2.2: Sequentially reduce the preheating temperature of the Nth sublayer to the 1st sublayer of the deposition layer / column composite structure region (3-2), wherein the preheating temperature of the Nth sublayer is <600℃ and the preheating temperature of the 1st sublayer is ≤150℃, and the particle size of the powder used for deposition is 10-75μm; during the deposition process, immediately cool the deposited coating after each spraying. Step 2.3: Preheat the substrate to 600°C again and deposit the first layered structure region (3-1). The powder particle size used for deposition is 10-45μm. After deposition, allow the first layered structure region (3-1) to cool naturally to room temperature.

7. The method for preparing a corrosion-resistant compressive strain layer / column composite thermal insulation coating according to claim 6, characterized in that, In step 1, a metal bonding layer (2) is prepared on the upper surface of the substrate (1) by means of atmospheric plasma spraying with deoxidation treatment, supersonic flame spraying, low-pressure plasma spraying or cold spraying.

8. The method for preparing a corrosion-resistant strain-resistant layer / column composite thermal insulation coating according to claim 6, characterized in that, In step 2, a ceramic heat insulation layer (3) is prepared on the metal bonding layer (2) by atmospheric plasma spraying.

9. The method for preparing a corrosion-resistant strain-resistant layer / column composite thermal insulation coating according to claim 6, characterized in that, In steps 2.1 to 2.2, the cooling gas is nitrogen or air, and the cooling gas pressure is 0.4-0.8 MPa.

10. The method for preparing a corrosion-resistant strain-resistant layer / column composite thermal insulation coating according to claim 6, characterized in that, In step 2.2, the preheating temperature of the substrate is reduced by 100-250℃ each time.

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