A method for improving the bond strength of plasma sprayed coatings

Abstract

This invention discloses a method for improving the bonding strength of plasma-sprayed coatings, comprising the following steps: (1) integrally forming a substrate and a micro-texture array of tenon and mortise structures on its surface using laser melting 3D printing technology; (2) plasma-spraying a NiCoCrAlY coating or a YSZ coating onto the substrate surface formed in step (1). The micro-texture array is a linear array or a grid-shaped interlaced array. The method of this invention utilizes 3D printing technology to directly print and prepare the substrate material while simultaneously constructing a "tenon and mortise" micro-texture with a mechanical interlocking effect on its surface, thereby avoiding potential damage to the substrate material caused by traditional sandblasting or subtractive roughening processes. The method of this invention uses 3D printing to integrally form the substrate and its surface "tenon and mortise" micro-texture, which is simple and efficient. No other post-processing is required, and plasma spraying can be performed directly on its surface, thereby improving the bonding strength between the coating and the substrate, and has broad application prospects.

Description

Technical Field

[0001] This invention relates to a method for improving the bonding strength of plasma-sprayed coatings, belonging to the field of additive manufacturing and surface engineering technology for metal materials. Background Technology

[0002] Plasma spraying technology boasts numerous advantages, including high heat source temperature, a wide variety of sprayable materials, high jet velocity, high deposition efficiency, and minimal thermal impact on the workpiece. The resulting ceramic coatings exhibit excellent properties such as wear resistance, high-temperature resistance, corrosion resistance, and oxidation resistance, finding wide application in the manufacturing and repair of hundreds of parts in aerospace, equipment remanufacturing, light industry, and automotive industries. However, despite these advantages, the mechanical bonding between the coating and the substrate results in weak adhesion, significantly impacting the coating's service performance and lifespan. Under extreme environments such as ultra-high temperatures and harsh wear conditions, the coating is prone to detachment and failure, limiting its application in extremely complex working conditions.

[0003] Numerous studies have found that the bonding strength between plasma-sprayed coatings and the substrate largely depends on the substrate conditions (cleanliness and roughness). Therefore, substrate surface roughening pretreatment is considered a crucial step before coating. Sandblasting is a commonly used pretreatment method to improve the bonding strength of the sprayed coating. However, it is worth noting that sandblasting may introduce sand inclusions and cracks into the substrate surface, leading to reduced coating adhesion. Furthermore, traditional subtractive roughening techniques such as laser etching and machining inherently damage the substrate surface, inducing stress concentration and generating structural defects. These process damages not only reduce the intrinsic properties of the substrate but also affect the material's service life and reliability.

[0004] Therefore, there is an urgent need to design a new method to improve the bonding strength between plasma-sprayed coatings and the substrate interface in order to solve the above problems. Summary of the Invention

[0005] The purpose of this invention is to propose a new method to improve the interfacial bonding strength between plasma sprayed coatings and substrates, so as to solve the bottleneck problem that existing plasma sprayed coatings are prone to peeling and failure in harsh environments such as high temperature, high erosion or high wear due to weak interfacial bonding, as well as the defects of traditional substrate surface pretreatment processes (such as sandblasting and laser etching) such as limited interfacial bonding and easy damage to the substrate.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: A method for improving the adhesion strength of plasma-sprayed coatings includes the following steps: (1) Using laser melting 3D printing technology to integrally form a substrate and a micro-texture array of mortise and tenon structures on its surface; (2) Plasma spraying NiCoCrAlY coating or YSZ coating onto the substrate surface formed in step (1), i.e., selecting a metal coating represented by NiCoCrAlY or a ceramic coating represented by YSZ.

[0007] Preferably, in step (1), the microtexture array is a linear array or a grid-shaped interlaced array.

[0008] This invention utilizes 3D printing to create a micro-texture of mortise and tenon structures on a substrate surface. In other words, it integrally forms arrayed "mortises" on the substrate surface. During subsequent plasma spraying, these "mortises" and "mortises" can be joined, creating a strong mechanically interlocking interface between the plasma-sprayed coating and the substrate. By leveraging the physical interlocking properties of the mortise and tenon joints, the contact area between the coating and the substrate is significantly increased, thereby significantly enhancing the bonding strength between the coating and the substrate through a strong mechanical interlocking effect.

[0009] In this invention, the relevant parameters of the "mortise and tenon" microtexture have a crucial impact on the bonding strength of the plasma-sprayed coating. For example, if the microtexture spacing is too small or the depth is too shallow, the printing will not be formed properly, while if the microtexture spacing is too large, it will affect the bonding strength between the coating and the substrate. Therefore, preferably, the depth h of the mortise in the microtexture is 250-400 μm, the upper width a is 300-500 μm, and the lower width b is 500-700 μm; the spacing Δ between adjacent mortises is... l The depth h of the mortise in the microtexture is 300-400 μm, and the spacing Δ between adjacent mortises is 400-1200 μm. More preferably, the depth h of the mortise in the microtexture is 300-400 μm, and the spacing Δ between adjacent mortises is 400-1200 μm. l It is 500-1000μm.

[0010] Preferably, the thickness of the NiCoCrAlY coating is 400-600 μm, and the thickness of the YSZ coating is 400-600 μm.

[0011] Preferably, in step (1), the process parameters for laser melting 3D printing are: laser power: 200-400 W, scanning speed: 900-1100 mm / s, scanning spacing: 0.09-0.15 mm, and layer thickness: 0.03-0.06 mm.

[0012] Preferably, in step (1), the base material is stainless steel, a high-temperature alloy, or a refractory alloy. The stainless steel can be 316L stainless steel; the high-temperature alloy can be GH3625 nickel-based high-temperature alloy; and the refractory alloy can be a Ta-W alloy or an Nb-based alloy.

[0013] Preferably, in step (2), NiCoCrAlY powder is selected as the raw material for plasma spraying coating, and the particle size range of NiCoCrAlY powder is 15-45μm.

[0014] Preferably, in step (2), YSZ powder is selected as the raw material for plasma spraying coating, and the particle size range of YSZ powder is 15-45μm.

[0015] The beneficial effects of this invention are: The method of this invention utilizes 3D printing technology to directly print and prepare the substrate material while simultaneously constructing a mechanically interlocking "mortise and tenon" microtexture on its surface, thereby avoiding potential damage to the substrate material caused by traditional sandblasting or subtractive roughening processes. This novel, integrated "mortise and tenon" microtexture significantly increases the contact area and mechanical interlocking force between the coating and the substrate, effectively alleviating interfacial stress caused by thermal expansion mismatch. Pull-out and thermal shock tests verified that, compared to conventionally sandblasted surfaces, the coating on this "mortise and tenon" microtexture surface exhibits superior bonding strength and thermal shock resistance, significantly improving the coating's service reliability.

[0016] The method of this invention uses 3D printing to integrally form the substrate and its surface "mortise and tenon" microtexture, which is simple and efficient. No other post-processing is required, and plasma spraying can be performed directly on its surface, thereby improving the bonding strength between the coating and the substrate, and has broad application prospects. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the "mortise and tenon" microtexture in this invention. Among them, (a) shows a schematic diagram of the "mortise and tenon" microtexture; (b) shows that the microtexture is a linear array; and (c) shows that the microtexture is a grid-shaped interlaced array.

[0018] Figure 2 This is a cross-sectional morphology diagram of the "mortise and tenon" microtexture of the matrix in Example 1.

[0019] Figure 3 The image shows the test results of the coating's thermal shock resistance in Example 1.

[0020] Figure 4 This is a cross-sectional morphology diagram of the "mortise and tenon" microtexture of the matrix in Example 2.

[0021] Figure 5 The image shows the test results of the coating's thermal shock resistance in Example 2.

[0022] Figure 6 This is a cross-sectional morphology diagram of the "mortise and tenon" microtexture of the matrix in Example 3.

[0023] Figure 7The image shows the test results of the coating's thermal shock resistance in Example 3.

[0024] Figure 8 This is a cross-sectional morphology diagram of the "mortise and tenon" microtexture of the matrix in Example 4.

[0025] Figure 9 The image shows the test results of the coating's thermal shock resistance in Example 4.

[0026] Figure 10 This is a cross-sectional morphology diagram of the "mortise and tenon" microtexture of the matrix in Example 5.

[0027] Figure 11 This is a cross-sectional morphology diagram of the "mortise and tenon" microtexture of the matrix in Example 6.

[0028] Figure 12 This is a cross-sectional morphology diagram of the "mortise and tenon" microtexture of the matrix in Example 7.

[0029] Figure 13 This is a cross-sectional morphology diagram of the "mortise and tenon" microtexture of the matrix in Comparative Example 1.

[0030] Figure 14 This is a cross-sectional morphology diagram of the "mortise and tenon" microtexture of the matrix in Comparative Example 2.

[0031] Figure 15 The image shows the thermal shock resistance test results of the coating in Comparative Example 3. Detailed Implementation

[0032] The technical solution of the present invention will be clearly and completely described below through embodiments, but the scope of protection and implementation of the present invention are not limited thereto.

[0033] This invention employs 3D printing to simultaneously form a substrate material and fabricate different "mortise and tenon" microtextures on its surface. The microtexture arrays are divided into linear arrays and grid-like interlaced arrays, such as... Figure 1 As shown. The relevant parameters of the "mortise and tenon" microtexture are: depth h = 250-400 μm, upper width a = 300-500 μm, lower width b = 500-700 μm; the spacing Δ between adjacent mortises... l The size is 400-1200μm.

[0034] In this invention, the substrate material can be stainless steel, high-temperature alloy, or refractory alloy. The coating material can be a metallic coating material or a ceramic coating material. In the following embodiments, 316L stainless steel powder, GH3625 nickel-based high-temperature alloy powder, Ta-10W alloy powder, and Nb-based alloy powder are selected as 3D printing substrate raw materials, and NiCoCrAlY powder and YSZ powder are selected as plasma spraying coating raw materials, with a particle size range of 15-45 μm.

[0035] Example 1

[0036] 1. 3D print a Ф25.4×5 mm 316 stainless steel cylindrical substrate, with laser power of 300 W, scanning speed of 980 mm / s, scanning spacing of 0.12 mm, layer thickness of 0.06 mm, and overall substrate height of 5 mm.

[0037] 2. Preset parameters for V-1 "mortise and tenon" microtexture: upper width a: 400 μm, lower width b: 600 μm, depth h: 300 μm, spacing △ l 1000 μm. After normal scanning and forming a height of 4.7 mm, the remaining 0.3 mm is... Figure 1 The "mortise and tenon" structure shown is scanned (1000 μm spacing, linear array), and a V-1 matrix is ​​ultimately fabricated. The micro-textured forming effect of the "mortise and tenon" structure in the V-1 matrix is ​​examined, and the cross-sectional morphology is as follows. Figure 2 As shown.

[0038] 3. A NiCoCrAlY coating with a thickness of approximately 520 μm was directly plasma-sprayed onto the V-1 substrate surface. Pull-out tests were conducted using a tensile testing machine, and the bonding strength of the coating was 36 MPa.

[0039] A YSZ coating with a thickness of approximately 550 μm was directly plasma-sprayed onto the V-1 substrate to prepare sample 1. Tensile testing was performed on sample 1 using a tensile testing machine. The coating's bonding strength was only 3 MPa. Simultaneously, a thermal shock resistance test was conducted (single cycle: stable ablation at 1500℃ for 1 min followed by water cooling). After three cycles of thermal shock, the coating detached. Figure 3 As shown.

[0040] Example 2

[0041] 1. 3D print a Ф25.4×5 mm 316 stainless steel cylindrical substrate, with laser power of 300 W, scanning speed of 980 mm / s, scanning spacing of 0.12 mm, layer thickness of 0.06 mm, and overall substrate height of 5 mm.

[0042] 2. Preset parameters for the V-2 "mortise and tenon" microtexture: upper width a: 400 μm, lower width b: 600 μm, depth h: 300 μm, spacing △ l 500 μm. After normal scanning and shaping to a height of 4.7 mm, the remaining 0.3 mm is... Figure 1 The "mortise and tenon" structure scan shown (500 μm spacing, linear array) was ultimately used to fabricate the V-2 matrix. The micro-textured forming effect of the "mortise and tenon" structure in the V-2 matrix was examined, and the cross-sectional morphology is as follows... Figure 4 As shown.

[0043] 3. A NiCoCrAlY coating with a thickness of approximately 520 μm was directly plasma-sprayed onto the V-2 substrate surface. Pull-out tests were conducted using a tensile testing machine, and the bonding strength of the coating was 21 MPa.

[0044] A YSZ coating with a thickness of approximately 550 μm was directly plasma-sprayed onto the V-2 substrate to prepare sample 2. Tensile testing was performed on sample 2 using a tensile testing machine. The coating's bonding strength was only 13 MPa. Simultaneously, a thermal shock resistance test was conducted (single cycle: stable ablation at 1500℃ for 1 min followed by water cooling). After five cycles of thermal shock, the coating detached. Figure 5 As shown.

[0045] Example 3

[0046] 1. 3D print a Ф25.4×5 mm 316 stainless steel cylindrical substrate, with laser power of 300 W, scanning speed of 980 mm / s, scanning spacing of 0.12 mm, layer thickness of 0.06 mm, and overall substrate height of 5 mm.

[0047] 2. Preset parameters for V-3 "mortise and tenon" microtexture: upper width a: 400 μm, lower width b: 600 μm, depth h: 300 μm, spacing △ l 1000 μm. After normal scanning and forming a height of 4.7 mm, the remaining 0.3 mm is... Figure 1 The mortise and tenon structure shown is scanned (1000 μm spacing, crisscross array), and a V-3 matrix is ​​ultimately fabricated. The micro-textured forming effect of the mortise and tenon structure in the V-3 matrix is ​​examined, and the cross-sectional morphology is as follows. Figure 6 As shown.

[0048] 3. A NiCoCrAlY coating with a thickness of approximately 520 μm was directly plasma-sprayed onto the V-3 substrate surface. Pull-out tests were conducted using a tensile testing machine, and the bonding strength of the coating was 39 MPa.

[0049] A YSZ coating with a thickness of approximately 550 μm was directly plasma-sprayed onto the V-3 substrate to prepare sample 3. Tensile testing was performed on sample 3 using a tensile testing machine. The coating's adhesion strength was 16 MPa. Simultaneously, a thermal shock resistance test was conducted (single cycle: stable ablation at 1500℃ for 1 min followed by water cooling). After 9 cycles of thermal shock, the coating detached. Figure 7 As shown.

[0050] Example 4

[0051] 1. 3D print a Ф25.4×5 mm 316 stainless steel cylindrical substrate, with laser power of 300 W, scanning speed of 980 mm / s, scanning spacing of 0.12 mm, layer thickness of 0.06 mm, and overall substrate height of 5 mm.

[0052] 2. Preset parameters for V-4 "mortise and tenon" microtexture: upper width a: 400 μm, lower width b: 600 μm, depth h: 300 μm, spacing △ l 500 μm. After normal scanning and shaping to a height of 4.7 mm, the remaining 0.3 mm is... Figure 1 The mortise and tenon structure shown is scanned (500 μm spacing, crisscross array), and a V-4 matrix is ​​ultimately fabricated. The micro-textured forming effect of the mortise and tenon structure in the V-4 matrix is ​​examined, and the cross-sectional morphology is as follows. Figure 8 As shown.

[0053] 3. A NiCoCrAlY coating with a thickness of approximately 520 μm was directly plasma-sprayed onto the V-4 substrate surface. Pull-out tests were conducted using a tensile testing machine, and the bonding strength of the coating was 23 MPa.

[0054] A YSZ coating with a thickness of approximately 550 μm was directly plasma-sprayed onto the V-4 substrate to prepare sample 4. Tensile testing was performed on sample 4 using a tensile testing machine. The coating's bonding strength was 14 MPa. Simultaneously, a thermal shock resistance test was conducted (single cycle: stable ablation at 1500℃ for 1 min followed by water cooling). After 6 cycles of thermal shock, the coating detached. Figure 9 As shown.

[0055] Example 5

[0056] 1. 3D print a GH3625 nickel-based high-temperature alloy cylindrical substrate with a diameter of Ф25.4×5 mm. The laser power is 300W, the scanning speed is 1000 mm / s, the scanning spacing is 0.11 mm, the layer thickness is 0.03 mm, and the overall height of the substrate is 5 mm.

[0057] 2. Preset parameters for the "mortise and tenon" microtexture of the GH3625 nickel-based superalloy matrix: upper width a: 400 μm, lower width b: 600 μm, depth h: 300 μm, spacing △ l 1000 μm. After normal scanning and forming a height of 4.7 mm, the remaining 0.3 mm is... Figure 1 The mortise and tenon structure scan shown (1000 μm spacing, crisscross array) was ultimately used to fabricate a GH3625 nickel-based superalloy matrix. The microstructure forming effect of the mortise and tenon joint in the GH3625 nickel-based superalloy matrix was examined, and the cross-sectional morphology is as follows... Figure 10 As shown.

[0058] 3. A YSZ coating with a thickness of approximately 550 μm was directly plasma-sprayed onto the surface of the GH3625 nickel-based superalloy substrate. A tensile test was performed on the GH3625 nickel-based superalloy substrate using a tensile testing machine, and the adhesion strength of the coating was 15 MPa.

[0059] Example 6

[0060] 1. 3D print a Ф25.4×5 mm Ta-10W (where Ta: 90 wt%, W: 10 wt%) alloy cylindrical substrate, with laser power of 300 W, scanning speed of 700 mm / s, scanning spacing of 0.06 mm, layer thickness of 0.06 mm, and overall substrate height of 5 mm.

[0061] 2. Preset parameters for the "mortise and tenon" microtexture of the Ta-10W alloy matrix: upper width a: 400 μm, lower width b: 600 μm, depth h: 300 μm, spacing △ l 1000 μm. After normal scanning and forming a height of 4.7 mm, the remaining 0.3 mm is... Figure 1 The mortise and tenon structure shown is scanned (1000 μm spacing, crisscross array), and a Ta-10W alloy matrix was finally fabricated. The microstructure forming effect of the mortise and tenon joint in the Ta-10W alloy matrix was examined, and the cross-sectional morphology is as follows. Figure 11 As shown.

[0062] 3. A YSZ coating with a thickness of approximately 550 μm was directly plasma-sprayed onto the surface of the Ta-10W alloy substrate. Pull-out tests were conducted on the Ta-10W alloy substrate using a tensile testing machine, and the coating's adhesion strength was 18 MPa.

[0063] Example 7

[0064] 1. 3D printing a cylindrical substrate of Nb-based alloy (Nb521, where Nb: 93 wt%, W: 4.9 wt%, Mo: 2.1 wt%) with a diameter of Ф25.4×5 mm. The laser power is 200 W, the scanning speed is 800 mm / s, the scanning spacing is 0.06 mm, the layer thickness is 0.06 mm, and the overall height of the substrate is 5 mm.

[0065] 2. Preset parameters for the "mortise and tenon" microtexture of the Nb-based alloy matrix: upper width a: 400 μm, lower width b: 600 μm, depth h: 300 μm, spacing Δ l 1000 μm. After normal scanning and forming a height of 4.7 mm, the remaining 0.3 mm is... Figure 1The mortise and tenon structure shown is scanned (1000 μm spacing, crisscross array), and a Nb-based alloy matrix is ​​ultimately fabricated. The microstructure forming effect of the mortise and tenon joint in the Nb-based alloy matrix is ​​examined, and the cross-sectional morphology is as follows. Figure 12 As shown.

[0066] 3. A YSZ coating with a thickness of approximately 550 μm was directly plasma-sprayed onto the surface of the Nb-based alloy substrate. Pull-out tests were conducted on the Nb-based alloy substrate using a tensile testing machine, and the coating's adhesion strength was 14 MPa.

[0067] Comparative Example 1 1. 3D print a Ф25.4×5 mm 316 stainless steel cylindrical substrate, with laser power of 300 W, scanning speed of 980 mm / s, scanning spacing of 0.12 mm, layer thickness of 0.06 mm, and overall substrate height of 5 mm.

[0068] 2. The preset parameters for the "mortise and tenon" microtexture are: upper width a: 400 μm, lower width b: 600 μm, depth h: 300 μm, and spacing △ l 300 μm. After normal scanning and shaping to a height of 4.7 mm, the remaining 0.3 mm is... Figure 1 The mortise and tenon structure shown is scanned (linear array) and ultimately used to fabricate the substrate. The micro-textured forming effect of the mortise and tenon structure in the substrate is examined, and the cross-sectional morphology is as follows: Figure 13 As shown. Under these microtexture parameters, the spacing between microtextures is too small, making 3D printing difficult. The roots of the microtextures break and exhibit irregular shapes. Due to the poor microtexture formation, it can no longer meet the needs of practical engineering applications, so related tests are no longer conducted.

[0069] Comparative Example 2 1. 3D print a Ф25.4×5 mm 316 stainless steel cylindrical substrate, with laser power of 300 W, scanning speed of 980 mm / s, scanning spacing of 0.12 mm, layer thickness of 0.06 mm, and overall substrate height of 5 mm.

[0070] 2. The preset parameters for the "mortise and tenon" microtexture are: upper width a: 400 μm, lower width b: 600 μm, depth h: 200 μm, and spacing △ l 500 μm. After normal scanning and shaping to a height of 4.7 mm, the remaining 0.2 mm is... Figure 1 The mortise and tenon structure shown is scanned (linear array) and ultimately used to fabricate the substrate. The micro-textured forming effect of the mortise and tenon structure in the substrate is examined, and the cross-sectional morphology is as follows: Figure 14As shown in the figure. Under these microtexture parameters, the microtexture depth is too shallow, resulting in the 3D-printed microtexture not exhibiting an inclination angle and failing to form a "mortise and tenon" interlocking structure, which no longer meets the practical needs of engineering. Therefore, related tests are no longer conducted.

[0071] Comparative Example 3 1. 3D printing a Ф25.4×5 mm non-microtextured 316 stainless steel cylindrical substrate, with laser power of 300W, scanning speed of 980 mm / s, scanning spacing of 0.12 mm, layer thickness of 0.06 mm, and overall substrate height of 5 mm.

[0072] 2. A 316 stainless steel cylindrical substrate without microtexture was first sandblasted, then a ~100 μm NiCoCrAlY transition layer was plasma-sprayed, and finally a YSZ coating with a thickness of approximately 450 μm was sprayed to prepare sample 5. A tensile test was performed on sample 5 using a tensile testing machine. The coating's bonding strength was only 5 MPa. Simultaneously, a thermal shock resistance test was conducted (single cycle: stable ablation at 1500℃ for 1 min followed by water cooling). After three cycles of thermal shock, the coating detached. Figure 15 As shown.

Claims

1. A method for improving the bonding strength of plasma-sprayed coatings, characterized in that, Includes the following steps: (1) Using laser melting 3D printing technology to integrally form a substrate and a micro-texture array of mortise and tenon structures on its surface; (2) Plasma spraying NiCoCrAlY coating or YSZ coating onto the substrate surface formed in step (1).

2. The method for improving the bonding strength of plasma-sprayed coatings according to claim 1, characterized in that, In step (1), the microtexture array is a linear array or a grid-shaped interlaced array.

3. The method for improving the bonding strength of plasma-sprayed coatings according to claim 1 or 2, characterized in that, The depth h of the mortises in the microtexture is 250-400 μm, the upper width a is 300-500 μm, and the lower width b is 500-700 μm; the spacing Δ between adjacent mortises l The size is 400-1200μm.

4. The method for improving the bonding strength of plasma-sprayed coatings according to claim 3, characterized in that, The depth h of the mortises in the microtexture is 300-400 μm, and the spacing Δ between adjacent mortises is... l It is 500-1000μm.

5. The method for improving the bonding strength of plasma-sprayed coatings according to claim 1 or 2, characterized in that, The thickness of the NiCoCrAlY coating is 400-600 μm, and the thickness of the YSZ coating is 400-600 μm.

6. The method for improving the bonding strength of plasma-sprayed coatings according to claim 1 or 2, characterized in that, In step (1), the process parameters for laser melting 3D printing are: laser power: 200-400 W, scanning speed: 700-1000 mm / s, scanning spacing: 0.06-0.15 mm, and layer thickness: 0.04-0.06 mm.

7. The method for improving the bonding strength of plasma-sprayed coatings according to claim 1 or 2, characterized in that, In step (1), the substrate material is stainless steel, high-temperature alloy and refractory alloy.

8. The method for improving the bonding strength of plasma-sprayed coatings according to claim 7, characterized in that, The stainless steel is 316L stainless steel; the high-temperature alloy is GH3625 nickel-based high-temperature alloy; the refractory alloy is Ta-W alloy or Nb-based alloy.

9. The method for improving the bonding strength of plasma-sprayed coatings according to claim 1 or 2, characterized in that, In step (2), NiCoCrAlY powder is selected as the raw material for plasma spraying coating, and the particle size range of NiCoCrAlY powder is 15-45μm.

10. The method for improving the bonding strength of plasma-sprayed coatings according to claim 1 or 2, characterized in that, In step (2), YSZ powder is selected as the raw material for plasma spraying coating, and the particle size range of YSZ powder is 15-45μm.

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