A deposit for enhancing the shear strength of a coating and a method of spraying the same

Abstract

This invention discloses a deposit body for enhancing the shear strength of a coating and its spraying method, belonging to the field of material surface modification and coating technology. (1) Determine the deformation of the deposited particles in the anchoring layer and the deformation of the upper particles; (2) Design the temperature of the substrate and the sprayed powder material so that the relative deformation of the two materials meets the requirements; (3) Adjust the spraying process parameters so that the flight speed of the sprayed powder material meets the requirements; (4) Perform the first spraying operation so that the particles are dispersed and deposited on the substrate surface; (5) Redesign the temperature of the substrate and the sprayed powder material so that the relative deformation of the two materials meets the new requirements; (6) Adjust the spraying process parameters so that the flight speed of the sprayed powder material meets the requirements, and perform the second spraying operation until the sample preparation is completed, resulting in a deposit body with a lower layer of spherical dispersed deposited particles anchoring layer and an upper layer of flat deformed particles after deposition.

Description

Technical Field

[0001] This invention belongs to the field of material surface modification and coating technology, specifically relating to a deposit that enhances the shear strength of a coating and its spraying method. Background Technology

[0002] Shear strength is the ability of a coating material to resist deformation and failure under shear force. In the aerospace field, due to the influence of thermal and mechanical stress, components often fail prematurely during service. Components with good shear strength can effectively resist the shear force of high-speed airflow, avoid damage caused by excessive heating, effectively reduce deformation under shear loading in engineering applications, and improve fatigue life under dynamic loads (such as vibration, impact, or cyclic loading).

[0003] Methods to improve shear strength include surface treatment and coating process optimization. Surface pretreatment, such as sandblasting, mechanical grinding, and surface activation, creates an active surface and improves coating adhesion. However, this method is technically demanding and its effects are inconsistent, thus affecting the improvement of shear strength. Coating process optimization improves the coating's shear strength by optimizing parameters such as coating thickness and ambient temperature. However, traditional spraying methods cannot balance various coating properties; for example, improving shear strength may reduce wear resistance, corrosion resistance, and thermal conductivity. Since there is an urgent need for components with high shear strength in aerospace and other fields, existing methods for improving shear strength suffer from the aforementioned problems, thus requiring more efficient methods to enhance shear strength. Summary of the Invention

[0004] In order to overcome the shortcomings of the prior art, the present invention aims to provide a deposit that enhances the shear strength of the coating and its spraying method, so as to solve the technical problem that the coating is easy to peel off due to poor shear surface stress performance.

[0005] To achieve the above objectives, the present invention employs the following technical solution:

[0006] In a first aspect, the present invention discloses a deposit body for enhancing the shear strength of a coating, comprising a lower layer of spherical dispersed deposited particles anchoring a layer and an upper layer of post-deposition flattened deformed particles.

[0007] Preferably, dispersed deposition refers to taking a representative area of ​​1mm×1mm on the substrate surface, where the total area of ​​the sprayed particles in the area is in the range of 20% to 40% of the total area of ​​the area, and there are no deposited particles that are connected in sheets and the particles do not aggregate.

[0008] Preferably, in the spherical dispersed deposited particle anchoring layer, the ratio of the actual longest size of the deposited spherical particles to the diameter of the equivalent area circle of the cross-section of a single spherical particle is ≤1.3.

[0009] Preferably, in the post-deposition flat deformable particle layer, the ratio of the actual longest dimension of the flat deformable particle to the diameter of the area equivalent circle of a single flat deformable particle cross-section is greater than 1.7.

[0010] Preferably, the porosity of the flattened deformed particle layer after deposition is <1%.

[0011] Preferably, in the spherical dispersed deposition particle anchoring layer, the depth of the spherical dispersed deposition particles embedded in the matrix is ​​greater than 50% of the diameter of the spherical dispersed deposition particles.

[0012] A second aspect of the present invention discloses a spraying method for the above-described deposit that enhances the shear strength of the coating, comprising the following steps:

[0013] 1) Controlling the relative deformation between the sprayed powder and the substrate to be sprayed, wherein the relative deformation includes one or more of the following: powder particle hardness / substrate hardness > 130%, powder particle yield strength / substrate yield strength > 120%, and powder particle elastic modulus / substrate elastic modulus > 120%;

[0014] 2) Adjust the spraying process parameters so that the flight speed of the sprayed powder is greater than the critical speed of the sprayed powder material;

[0015] 3) Perform the first spraying operation to disperse and deposit the sprayed powder onto the substrate surface;

[0016] 4) Adjusting the relative deformation between the powder and the matrix, wherein the relative deformation includes one or more of the following: powder particle hardness / matrix hardness = 90%~110%, powder particle yield strength / matrix yield strength = 90%~110%, and powder particle elastic modulus / matrix elastic modulus = 90%~110%;

[0017] 5) Adjust the spraying process parameters so that the flight speed of the sprayed powder material is greater than the critical speed of the sprayed powder material;

[0018] 6) Perform a second spraying until the sample preparation is complete.

[0019] Preferably, in steps 2) and 5), the spraying process parameters include the spraying method, spraying temperature, and powder feeding pressure.

[0020] Preferably, in step 3), after spraying, the sprayed powder is deposited on the substrate surface, and the depth of the particles embedded in the substrate is greater than 50% of the diameter of the sprayed powder particles.

[0021] Preferably, in step 4), the relative deformation between the powder and the matrix is ​​controlled by lowering the matrix temperature or raising the powder temperature.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] This invention provides a deposit that enhances the shear strength of a coating. The lower layer consists of spherical dispersed deposited particles that anchor to the substrate, enhancing coating adhesion. The upper layer is a flattened deformed particle layer. These flattened deformed particles have a larger surface area than the spherical particles, resulting in a larger contact area with the lower spherical dispersed deposited particles, thus strengthening the bond between the upper and lower layers. Furthermore, they can be tightly stacked, reducing gaps between particles and increasing the overall stability of the coating, preventing the deposit from loosening or collapsing under external forces. The cooperation between the spherical dispersed deposited particle anchoring layer and the post-deposition flattened deformed particle layer increases the shear strength between the deposit and the substrate surface, preventing coating peeling due to shear forces.

[0024] The spraying method for the above-mentioned deposit provided by this invention firstly ensures that the sprayed powder is spherical by controlling the relative deformation between the sprayed powder and the substrate (powder particle hardness / substrate hardness > 130%, powder particle yield strength / substrate yield strength > 120%, and powder particle elastic modulus / substrate elastic modulus > 120%). Secondly, by controlling the flight speed of the sprayed powder to be greater than the critical speed of the sprayed powder material, it ensures that the spherical particles reach the substrate surface and that the depth of the spherical particles embedded in the substrate is greater than 50%. The diameter of the spherical particles; secondly, by adjusting the relative deformation between the sprayed powder and the substrate to be sprayed (powder particle hardness / substrate hardness = 90%~110%, powder particle yield strength / substrate yield strength = 90%~110%, and powder particle elastic modulus / substrate elastic modulus = 90%~110%), it can be ensured that the sprayed powder is a flat deformed particle; finally, by controlling the flight speed of the sprayed powder material to be greater than the critical speed of the sprayed powder material, it can be ensured that the flat deformed particles reach the surface of the spherical dispersed deposition particle anchoring layer. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the deposit obtained by the spraying method for enhancing the shear strength of the coating according to the present invention;

[0026] Figure 2 This is a schematic diagram showing the actual longest dimension (df) of the deposited spherical particles of the present invention and the diameter (dc) of the equivalent area circle of the cross-section of a single spherical particle. Detailed Implementation

[0027] To enable those skilled in the art to understand the features and effects of the present invention, the following descriptions and definitions are only general descriptions of the terms and expressions mentioned in the specification and claims. Unless otherwise specified, all technical and scientific terms used herein have the ordinary meaning understood by those skilled in the art regarding the present invention, and in the event of any conflict, the definitions in this specification shall prevail.

[0028] The theories or mechanisms described and disclosed herein, whether right or wrong, should not in any way limit the scope of the invention, that is, the contents of the invention can be implemented without being limited by any particular theory or mechanism.

[0029] In this document, all features defined by numerical ranges or percentage ranges, such as numerical values, quantities, contents, and concentrations, are for the sake of brevity and convenience only. Accordingly, descriptions of numerical ranges or percentage ranges should be considered as covering and specifically disclosing all possible sub-ranges and individual numerical values ​​(including integers and fractions) within those ranges.

[0030] In this article, unless otherwise specified, “contains,” “includes,” “containing,” “has,” or similar terms cover the meanings of “composed of” and “mainly composed of,” for example, “A contains a” covers the meanings of “A contains a and others” and “A contains only a.”

[0031] For the sake of brevity, not all possible combinations of the technical features in each implementation scheme or embodiment are described herein. Therefore, as long as there is no contradiction in the combination of these technical features, the technical features in each implementation scheme or embodiment can be combined arbitrarily, and all possible combinations should be considered within the scope of this specification.

[0032] Unless otherwise specified, " / " represents proportion in this article.

[0033] This invention provides a spraying method for enhancing the shear strength of a coating, comprising the following steps:

[0034] Step 1: Make a preliminary judgment on the hardness of the substrate and the powder coating material, design the temperature of the substrate and the powder coating, and increase the substrate temperature or change the powder temperature to control the relative deformation of the powder and the substrate.

[0035] Among them, controlling the relative deformation between the sprayed powder and the substrate includes one or more of the following: powder particle hardness / substrate hardness > 130%, powder particle yield strength / substrate yield strength > 120%, and powder particle elastic modulus / substrate elastic modulus > 120%.

[0036] Step 2: Adjust the spraying process parameters so that the flight speed of the sprayed powder material is greater than the critical speed of the sprayed powder material;

[0037] The adjustment of spraying process parameters includes, but is not limited to, spraying method, spraying temperature and powder feeding pressure.

[0038] Step 3: Perform the first spraying operation to disperse and deposit the particles onto the substrate surface;

[0039] Among them, dispersed deposition refers to taking a representative area of ​​1mm×1mm on the substrate surface, satisfying that the total area of ​​the sprayed particles in the area is in the range of 20% to 40% of the total area of ​​the area, so that after spraying, the sprayed powder is deposited on the substrate surface and the depth of the particles embedded in the substrate is greater than 50% of the diameter of the sprayed powder particles.

[0040] Step 4: Adjust the substrate and powder coating temperatures, lowering the substrate temperature or increasing the powder temperature to control the relative deformation between the powder and the substrate;

[0041] Among them, the control of the relative deformation between the sprayed powder and the substrate includes one or more of the following: powder particle hardness / substrate hardness = 90%~110%, powder particle yield strength / substrate yield strength = 90%~110%, and powder particle elastic modulus / substrate elastic modulus = 90%~110%.

[0042] Step 5: Adjust the spraying process parameters so that the flight speed of the sprayed powder material is greater than the critical speed of the sprayed powder material;

[0043] Step 6: Perform a second spraying until the sample preparation is complete.

[0044] The deposit obtained by the above-described method provided by this invention, such as Figure 1 As shown, the upper layer is an anchoring layer of spherical dispersed deposited particles, and the lower layer is a layer of flattened and deformed particles after deposition.

[0045] Among them, in the spherical dispersed sedimentary particle anchoring layer, such as Figure 2 As shown, the ratio of the actual longest dimension (df) of the deposited spherical particles to the diameter (dc) of the equivalent area circle of a single spherical particle's cross-section is ≤1.3. Dispersed deposition refers to arbitrarily selecting a representative area of ​​1mm × 1mm on the substrate surface, satisfying that the total area of ​​the sprayed particles in the area / the total area of ​​the area is within the range of 20% to 40%, and there are no deposited particles in sheets, nor do the particles aggregate. In the post-deposition flat deformed particle layer, the ratio of the actual longest dimension (df) of the flat deformed particles to the diameter (dc) of the equivalent area circle of a single flat deformed particle's cross-section is >1.7, and the porosity is <1%.

[0046] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0047] The following examples use instruments and equipment conventional in the art. Experimental methods in the following examples, unless otherwise specified, are generally performed under standard conditions or as recommended by the manufacturer. All raw materials used in the following examples are conventional commercially available products with specifications in the art, unless otherwise stated.

[0048] Example 1

[0049] A spraying method for enhancing the shear strength of a coating includes the following steps:

[0050] Step 1: Select TC4 matrix and nickel-based alloy 718 powder. At room temperature (25℃), the Vickers hardness of the matrix is ​​332HV, and the Vickers hardness of the powder at 500℃ during the spraying process is 330HV. After scanning electron microscopy observation and statistical analysis, the average particle size of nickel-based alloy 718 powder is 45μm.

[0051] The ratio of the hardness of the nickel-based alloy 718 powder (500℃) to the hardness of the TC4 matrix (25℃) is 99.4%, which does not meet the requirement of a hardness ratio greater than 130% for spraying. The TC4 matrix is ​​then heated to 300℃ using a heating table. At this temperature, its Vickers hardness is 230 HV. The ratio of the hardness of the nickel-based alloy 718 powder (500℃) to the hardness of the TC4 matrix (300℃) is 143.5%, which meets the requirement of greater than 130%.

[0052] Step 2: The required flight speed of the nickel-based alloy 718 powder for this spraying is greater than 320 m / s. The measured average flight speed of the powder used in the spraying process is 358 m / s, which meets the condition of being greater than the critical speed.

[0053] Step 3: Perform the first spraying operation, spraying nickel-based alloy 718 powder (500℃) onto the TC4 substrate heated to 300℃.

[0054] Five randomly selected areas, each 1 mm × 1 mm in size, were observed using a scanning electron microscope. The powder coating area was 0.21 mm². 2 0.23mm 2 0.25mm 2 0.28mm 2 and 0.20mm 2 The average area of ​​powder coating is 0.234 mm. 2The requirement is that the total area of ​​sprayed particles in the area is within the range of 20% to 40% of the total area of ​​the area.

[0055] The embedded depth of the sprayed nickel-based alloy 718 powder in the TC4 matrix is ​​approximately 32 μm, which meets the requirement that the particle embedding depth in the matrix is ​​greater than 50% of the particle diameter.

[0056] Step 4: Determine that the ratio of the hardness of the nickel-based alloy 718 powder (500℃) particles to the hardness of the TC4 matrix (at room temperature) is 99.4%, which satisfies the requirement that the ratio is within the range of 90% to 110%.

[0057] Step 5: The required flight speed of the nickel-based alloy 718 powder for this spraying is greater than 320 m / s. The measured average flight speed of the powder used in the spraying is 368 m / s, which meets the condition of being greater than the critical speed.

[0058] Step 6: Perform a second spraying operation, spraying nickel-based alloy 718 powder onto the TC4 substrate at room temperature; after the second spraying is completed, ensure that the coating completely covers the substrate surface.

[0059] Example 2

[0060] A spraying method for enhancing the shear strength of a coating includes the following steps:

[0061] Step 1: Select pure aluminum substrate and TC4 powder. The tensile elastic modulus of the substrate at room temperature (25℃) is 70 GPa, and the tensile elastic modulus of the powder at 400℃ during the spraying process is 85.5 GPa. After scanning electron microscopy observation and statistical analysis, the average particle size of TC4 powder is 38 μm.

[0062] The ratio of the tensile modulus of TC4 powder (400℃) to the tensile modulus of aluminum matrix (room temperature) is determined to be 122.1%, which meets the requirement of a modulus ratio greater than 120% for spraying.

[0063] Step 2: The spraying process requires the TC4 powder to have a flight speed greater than 350 m / s. The measured average flight speed of the spraying powder used was 392 m / s, which meets the condition of being greater than the critical speed.

[0064] Step 3: Perform the first spraying operation by spraying TC4 powder (400℃) onto the room temperature aluminum substrate.

[0065] Five randomly selected areas, each 1 mm × 1 mm in size, were observed using a scanning electron microscope. The powder coating area was 0.30 mm². 2 0.23mm 2 0.21mm 2 0.26mm 2 and 0.24mm 2 The average area of ​​powder coating is 0.248 mm. 2The requirement is that the total area of ​​sprayed particles in the area is within the range of 20% to 40% of the total area of ​​the area.

[0066] The TC4 powder is embedded to a depth of approximately 22 μm in the aluminum substrate, which meets the requirement that the particle embedding depth in the substrate is greater than 50% of the particle diameter.

[0067] Step 4: Determine the ratio of the tensile elastic modulus of TC4 powder (400℃) to the tensile elastic modulus of the aluminum matrix (room temperature). The ratio is 122.1%, which does not meet the requirement of being within the range of 90% to 110%. Increase the powder temperature during spraying to 550℃. At this point, the tensile elastic modulus of TC4 powder is 70.9 GPa. Determine the ratio of the tensile elastic modulus of TC4 powder (550℃) to the tensile elastic modulus of the aluminum matrix to be 101.3%, which meets the requirement of being within the range of 90% to 110%.

[0068] Step 5: The spraying process requires the TC4 powder to have a flight speed greater than 350 m / s. The measured average flight speed of the spraying powder is 385 m / s, which meets the condition of being greater than the critical speed.

[0069] Step 6: Perform a second spraying operation, spraying TC4 powder (550℃) onto the aluminum substrate at room temperature; after the second spraying is completed, ensure that the coating completely covers the substrate surface.

[0070] 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 deposit that enhances the shear strength of a coating, characterized in that, It includes a lower layer of spherical dispersed deposited particles anchoring the particles, and an upper layer of post-deposition flattened deformed particles. Dispersed deposition refers to taking a representative area of ​​1 mm × 1 mm on the substrate surface, where the total area of ​​the sprayed particles in the area is within the range of 20% to 40% of the total area of ​​the area, and there are no deposited particles that are connected in sheets and the particles do not aggregate; in the spherical dispersed deposition particle anchoring layer, the ratio of the actual longest size of the deposited spherical particles to the diameter of the equivalent area circle of the cross-section of a single spherical particle is ≤1.

3.

2. The deposit body for enhancing the shear strength of the coating according to claim 1, characterized in that, In the post-deposition flattened deformable particle layer, the ratio of the actual longest size of the flattened deformable particle to the diameter of the area equivalent circle of a single flattened deformable particle cross-section is greater than 1.

7.

3. The deposit body for enhancing the shear strength of the coating according to claim 1, characterized in that, The porosity of the flattened deformed particle layer after deposition is <1%.

4. The deposit body for enhancing the shear strength of the coating according to claim 1, characterized in that, In the spherical dispersed sedimentary particle anchoring layer, the depth of the spherical dispersed sedimentary particles embedded in the matrix is ​​greater than 50% of the diameter of the spherical dispersed sedimentary particles.

5. The spraying method for the deposited body with enhanced shear strength according to any one of claims 1 to 4, characterized in that, The steps are as follows: 1) Controlling the relative deformation between the sprayed powder and the substrate to be sprayed, wherein the relative deformation includes one or more of the following: powder particle hardness / substrate hardness > 130%, powder particle yield strength / substrate yield strength > 120%, and powder particle elastic modulus / substrate elastic modulus > 120%; 2) Adjust the spraying process parameters so that the flight speed of the sprayed powder is greater than the critical speed of the sprayed powder material; 3) Perform the first spraying operation to disperse and deposit the sprayed powder onto the substrate surface; 4) Adjusting the relative deformation between the powder and the matrix, wherein the relative deformation includes one or more of the following: powder particle hardness / matrix hardness = 90%~110%, powder particle yield strength / matrix yield strength = 90%~110%, and powder particle elastic modulus / matrix elastic modulus = 90%~110%. 5) Adjust the spraying process parameters so that the flight speed of the sprayed powder material is greater than the critical speed of the sprayed powder material; 6) Perform a second spraying until the sample preparation is complete.

6. The spraying method for the deposited body that enhances the shear strength of the coating according to claim 5, characterized in that, In steps 2) and 5), the spraying process parameters include the spraying method, spraying temperature, and powder feeding pressure.

7. The spraying method for the deposited body that enhances the shear strength of the coating according to claim 5, characterized in that, In step 3), after spraying, the sprayed powder is deposited on the substrate surface, and the depth of the particles embedded in the substrate is greater than 50% of the diameter of the sprayed powder particles.

8. The spraying method for the deposited body that enhances the shear strength of the coating according to claim 5, characterized in that, In step 4), the relative deformation between the powder and the matrix is ​​controlled by lowering the matrix temperature or raising the powder temperature.

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