Method for accurately obtaining three-dimensional surface morphology of sprayed layer

Abstract

The application discloses a method for accurately obtaining three-dimensional surface topography of a sprayed coating, and belongs to the technical field of coating surface treatment. A sample to be measured is placed inside an envelope formed by small columns; the sample to be measured and the small columns are solidified, polished and photographed to obtain a cross section of the sample to be measured; the polishing and photographing steps are repeated, and the polishing thickness is not more than 1 / 10 of the minimum feature of the surface fluctuation of the sample to be measured in the direction parallel to the upper surface of the sample to be measured; finally, the obtained cross section photos are imported into software with functions of reading and drawing graphs, two-dimensional topography curves of the cross section features of the combined sample and different positions of the sample to be measured in the cross section of the combined sample are extracted, and the two-dimensional topography curves are imported into software for constructing three-dimensional topography and placed according to the position relationship determined in the foregoing to obtain three-dimensional topography features of the sample to be measured. The method can more accurately predict the stress distribution and crack initiation and propagation behavior of the coating at complex topography during service.

Description

Technical Field

[0001] This invention belongs to the field of coating surface treatment technology, and specifically relates to a method for accurately obtaining the three-dimensional surface morphology of a sprayed coating. Background Technology

[0002] The coating on the substrate surface provides significant protection and extends the substrate's service life. However, coatings prepared using thermal spraying methods have high surface roughness, leading to stress concentration in harsh service environments and causing crack initiation. When multiple cracks propagate and merge, coating peeling failure occurs. Therefore, researching the influence of coating surface morphology on the cracking behavior of coatings during service is crucial for constructing a comprehensive theory of coating failure. While experimental studies cannot observe the processes of coating cracking and even peeling, these can be reproduced through finite element simulation, thus supplementing or verifying experimental results.

[0003] Currently, qualitative studies on coating failure behavior are mainly conducted by establishing two-dimensional coating models. However, two-dimensional simulations cannot accurately predict stress at complex morphologies. Furthermore, because cracks can bypass compressive stress regions in three-dimensional models, their behavior differs between two-dimensional and three-dimensional models. Establishing a three-dimensional coating model that reflects the true morphology of the coating can solve these problems, but accurately obtaining the three-dimensional surface morphology of the coating remains a significant technical challenge. Summary of the Invention

[0004] In order to overcome the shortcomings of the prior art, the present invention aims to provide a method for accurately obtaining the three-dimensional surface morphology of the sprayed coating, which solves the problem that the two-dimensional coating model in the prior art cannot accurately simulate the failure process of the coating.

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

[0006] This invention discloses a method for accurately obtaining the three-dimensional surface morphology of a sprayed coating, which is specifically carried out according to the following steps:

[0007] Step 1: Place the spray coating sample to be tested and at least three small pillars in the sample preparation mold, with the spray coating sample to be tested located inside the envelope formed by the small pillars;

[0008] Step 2: Curing the sprayed coating sample and the small column to be tested to obtain the combined sample;

[0009] Step 3: Polish the combined sample obtained in Step 2 to obtain a smooth and bright cross-section of the sprayed coating sample to be tested, and photograph the cross-section of the sprayed coating sample to be tested.

[0010] Step 4: Repeat the operation of Step 3, with the thickness of each polishing not exceeding 1 / 10 of the minimum feature of the surface undulation in the direction parallel to the upper surface of the coating to be tested;

[0011] Step 5: Import the photos of all the cross sections of the sprayed coating samples to be tested into software with image reading and drawing functions, extract the cross section features of the combined sample, and determine the positional relationship of each cross section of the combined sample.

[0012] Step 6: Extract the two-dimensional morphology curves of the sprayed coating sample at different positions in each cross section of the combined sample, import them into the software for constructing three-dimensional morphology, place them according to the positional relationship determined in Step 5, and obtain the three-dimensional morphology features of the sprayed coating sample to be tested.

[0013] Preferably, in step one, when the cross-sectional shapes of the small columns are the same, the axes of the small columns are not parallel to each other when they are placed.

[0014] More preferably, in step one, the small column is a cone or a column that is not parallel to each other.

[0015] Preferably, if the sample of the sprayed coating to be tested or the small column cannot be reliably positioned independently, it shall be fixed in an auxiliary manner.

[0016] Preferably, in step two, the specific steps of curing are as follows: add curable adhesive and acrylic powder into the sample preparation mold, and cure the sprayed coating sample and the small column to be tested.

[0017] More preferably, the difference between the volume average equivalent atomic number of the curable adhesive and that of the sprayed coating sample and the small column being tested exceeds 50%.

[0018] Preferably, the mass ratio of curable adhesive to acrylic powder is 4:5.

[0019] Preferably, the curable adhesive is any one of epoxy resin, acrylic resin, and polyester resin.

[0020] Preferably, the curing time is 30 to 60 minutes.

[0021] Preferably, in steps three and four, the cross-section of the sprayed coating sample under test is captured by scanning electron microscopy in backscatter mode.

[0022] Preferably, in step four, the polishing material, polishing force, and polishing time are controlled to ensure that the thickness of each polishing operation does not exceed 1 / 10 of the minimum feature of the surface undulations to be tested in the direction parallel to the upper surface of the coating layer to be tested.

[0023] Preferably, the specific steps of step five are as follows: import the extracted cross-sectional features of the combined specimen into software with image reading and drawing functions, move the small column cross-sections in each cross-section of the combined specimen, place the small column cross-sections inside the pre-drawn small columns, and obtain the positional relationship of the small column cross-sections; then, through the determined positional relationship of the small column cross-sections in the combined specimen, obtain the positional relationship of each cross-section in the combined specimen.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] This invention provides a method for accurately acquiring the three-dimensional surface morphology of a sprayed coating. The method involves placing the sample of the sprayed coating to be tested within an envelope formed by at least three small pillars to obtain a composite sample. The small pillars are used for positioning assistance, and at least three pillars ensure the formation of the envelope. Through multiple polishing and photographing of the cross-section of the sample, a certain thickness of coating is first polished away and the cross-section at that location is photographed to obtain the coating cross-sectional features. Then, another certain thickness of coating is polished away, and another cross-sectional feature is photographed. This process is repeated multiple times to obtain the two-dimensional surface morphology features of the sprayed coating at different locations. The smallest feature is selected based on the actual coating morphology characteristics. Each polishing thickness does not exceed 1 / 10 of the smallest feature in the direction parallel to the coating surface. Multiple polishing processes prevent feature loss and more accurately acquire the coating morphology features. Two-dimensional morphology curves at different locations of the sample from the cross-section of the composite sample are extracted and imported into software for constructing a three-dimensional morphology. The sample is placed according to a predetermined positional relationship to acquire the three-dimensional morphology features of the sample. Then, based on the acquired three-dimensional morphology of the coating sample, a three-dimensional coating model reflecting the true surface morphology of the coating is established. By establishing a three-dimensional realistic morphology coating model to simulate the occurrence of failure, compared with a two-dimensional coating model, it is possible to more accurately predict the stress distribution at complex morphologies and the initiation and propagation behavior of cracks during service.

[0026] Furthermore, for conical bodies or cylindrical bodies with non-parallel axes, the cross-sectional characteristics at any position parallel to the base are regularly known, facilitating comparison with the characteristics of the small column cross-sections on the composite specimen cross-section to determine the actual position of the composite specimen cross-section. The polishing depth can be calculated for conical bodies or cylindrical bodies with non-parallel axes based on interface changes, but the polishing depth cannot be calculated for bodies of equal diameter and placed parallel to each other.

[0027] Furthermore, when using a scanning electron microscope in backscatter mode, the greater the difference in the volume average equivalent atomic mass between the two materials, the more obvious the difference in the compositional contrast of the two materials will be on the fluorescent screen. In this invention, the difference between the volume average equivalent atomic mass of the curable adhesive and that of the sample and the small column being tested exceeds 50%, which makes the difference between the adhesive and the sample clear and easy to distinguish between them.

[0028] Furthermore, acrylic powder and curable adhesive are mixed in a mass ratio of 5:4 to form a liquid mounting adhesive. After being left to stand in the air for a period of time, the mounting adhesive cures and the mounting is completed. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the combined sample of three cones and the coating sample to be tested in Embodiment 1 of the present invention;

[0030] Figure 2 This is a schematic diagram of the combined sample of four triangular pyramids and the spray coating sample to be tested in Embodiment 2 of the present invention;

[0031] Figure 3 This is a schematic diagram of the combined sample of five square pyramids and the spray coating sample to be tested in Embodiment 3 of the present invention;

[0032] Figure 4 This is a schematic diagram of a combined sample of three non-parallel cylinders and the coating sample to be tested, as described in Embodiment 4 of the present invention.

[0033] Figure 5 This is a schematic diagram of a combined sample of four non-parallel triangular prisms and the coating sample to be tested, as shown in Embodiment 5 of the present invention.

[0034] Among them, 1-small column; 2-sample of the coating to be tested. Detailed Implementation

[0035] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0036] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0037] In this invention, the volume average equivalent atomic number = equivalent atomic number / density, and the equivalent atomic number is obtained by weighted averaging of the atomic numbers of each atom by molar ratio.

[0038] Example 1

[0039] The method for accurately obtaining the three-dimensional surface morphology of the sprayed coating in this embodiment includes the following steps:

[0040] Three cones, each with a base diameter and height of 3 cm, were machined and prepared. The cones and the sample to be tested were placed in a sample preparation mold. (See [reference]). Figure 1 The sample to be tested, coated with epoxy resin, is located inside an envelope formed by three cones, with its side parallel to the axes of the three cones. First, epoxy resin with a volume average equivalent atomic number exceeding 50% of the difference between the volume average equivalent atomic number of the sample and the cones was selected as the curable adhesive material. Then, 8g of epoxy resin and 10g of acrylic powder were mixed and poured into a mold, allowing it to cure for 30 minutes at room temperature to obtain the composite sample. After cutting the sample with a grinding wheel, the cross-section of the composite sample was progressively sanded using 240#, 600#, 800#, and 1000# sandpaper, followed by polishing to obtain a smooth and glossy cross-section. Backscattered images of the cross-section were then taken using a scanning electron microscope. By controlling the polishing material, polishing force, and polishing time, the thickness of each polishing step was ensured to not exceed 1 / 10 of the minimum feature of the surface undulations in the direction parallel to the coating surface. Import the acquired composite specimen cross-section photos into Adobe Illustrator software. Move the conical sections in each composite specimen cross-section to place them inside the pre-drawn cone to determine the positional relationship of each conical section. The positional relationship of each cross-section of the composite specimen is then determined. Extract the two-dimensional morphology curves at different positions of the sample to be tested in the composite specimen cross-section, import them into Solidworks software, and place them according to the positional relationship of each cross-section to obtain the three-dimensional morphology features of the sample to be tested.

[0041] Example 2

[0042] The method for accurately obtaining the three-dimensional surface morphology of the sprayed coating in this embodiment includes the following steps:

[0043] A triangular pyramid with four equilateral triangular bases, each 4cm in length and 4cm in height, was machined. The pyramid and the sample to be tested were placed in a sample preparation mold. (See [reference]). Figure 2The sample to be tested is located inside the envelope formed by four triangular pyramids, with the side of the sample parallel to the axes of the pyramids. First, acrylic resin with a volume average equivalent atomic number exceeding 50% of the difference between the volume average equivalent atomic number of the sample and the cone was selected as the curable adhesive material. 8g of acrylic resin and 10g of acrylic powder were mixed and poured into a mold, then allowed to cure for 40 minutes at room temperature to obtain the composite sample. After cutting the sample with a grinding wheel, the cross-section of the composite sample was progressively sanded using 240#, 600#, 800#, and 1000# sandpaper, followed by polishing to obtain a smooth and glossy cross-section. Backscattered images of the cross-section were then taken using a scanning electron microscope. By controlling the polishing material, polishing force, and polishing time, the thickness of each polishing step was ensured to not exceed 1 / 10 of the minimum feature of the surface undulations parallel to the coating surface. Import the acquired composite specimen cross-section photos into Photoshop software, move the triangular pyramid cross-sections of each composite specimen cross-section to place them inside the pre-drawn triangular pyramid to determine the positional relationship of each triangular pyramid cross-section, and the positional relationship of each cross-section of the composite specimen is thus determined; extract the two-dimensional morphology curves of different positions of the sprayed coating sample in the composite specimen cross-section, import them into Pro-E software, place them according to the positional relationship of each cross-section, and obtain the three-dimensional morphology features of the sprayed coating sample to be tested.

[0044] Example 3

[0045] The method for accurately obtaining the three-dimensional surface morphology of the sprayed coating in this embodiment includes the following steps:

[0046] Five square pyramids with square bases, sides of 4 cm, and height of 3 cm were machined. The pyramids and the sample to be tested were placed in a sample preparation mold. (See [reference]). Figure 3The sample to be tested is located inside the envelope formed by five square pyramids, with the side of the sample parallel to the axes of the pyramids. First, polyester resin with a volume average equivalent atomic number exceeding 50% of the difference between the volume average equivalent atomic number of the sample and the cone was selected as the curable adhesive material. 8g of polyester resin and 10g of acrylic powder were mixed and poured into a mold, then allowed to cure for 50 minutes at room temperature to obtain the composite sample. After cutting the sample with a grinding wheel, the cross-section of the composite sample was first polished using 240#, 600#, 800#, and 1000# sandpaper, then polished to obtain a smooth and glossy cross-section. Backscattered images of the cross-section were then taken using a scanning electron microscope. By controlling the polishing material, polishing force, and polishing time, the thickness of each polishing step was ensured to not exceed 1 / 10 of the minimum feature of the surface undulations parallel to the coating surface. Import the acquired composite specimen cross-section photos into Adobe Illustrator software. Move the quadrangular pyramid cross-sections in each composite specimen cross-section to place them inside the pre-drawn quadrangular pyramid to determine the positional relationship of each quadrangular pyramid cross-section. The positional relationship of each cross-section of the composite specimen is then determined. Extract the two-dimensional morphology curves at different positions of the sprayed coating sample to be tested in the composite specimen cross-section, import them into Solidworks software, and place them according to the positional relationship of each cross-section to obtain the three-dimensional morphology features of the sprayed coating sample to be tested.

[0047] Example 4

[0048] The method for accurately obtaining the three-dimensional surface morphology of the sprayed coating in this embodiment includes the following steps:

[0049] Three cylinders, each with a base diameter and height of 3 cm, were machined. These non-parallel cylinders, along with the sample to be tested, were placed in a sample preparation mold. (See [reference]). Figure 4The sample to be tested is located inside an envelope formed by three non-parallel cylinders, the axes of which are not parallel. First, epoxy resin with a volume average equivalent atomic number exceeding 50% of the difference between the volume average equivalent atomic number of the sample and the cone was selected as the curable adhesive material. 8g of epoxy resin and 10g of acrylic powder were mixed and poured into a mold, then allowed to cure for 60 minutes at room temperature to obtain the composite sample. After cutting the sample with a grinding wheel, the cross-section of the composite sample was first polished step-by-step using 240#, 600#, 800#, and 1000# sandpaper, then polished to obtain a smooth and glossy cross-section of the sample. Backscattered images of the cross-section were then taken using a scanning electron microscope. By controlling the polishing material, polishing force, and polishing time, the thickness of each polishing step was ensured to not exceed 1 / 10 of the minimum feature of the surface undulations in the direction parallel to the coating surface. Import the acquired composite specimen cross-section photos into Adobe Illustrator software. Move the cylindrical sections in each composite specimen cross-section to place them inside the pre-drawn cylinder to determine the positional relationship of each cylindrical section. The positional relationship of each section of the composite specimen is then determined. Extract the two-dimensional morphology curves at different positions of the sprayed coating sample in the composite specimen cross-section, import them into ABAQUS software, and place them according to the positional relationship of each section to obtain the three-dimensional morphology features of the sprayed coating sample.

[0050] Example 5

[0051] The method for accurately obtaining the three-dimensional surface morphology of the sprayed coating in this embodiment includes the following steps:

[0052] Four triangular prisms with equilateral triangular bases (4cm side length) and a height of 3cm were machined. The non-parallel triangular prisms and the sample to be tested were placed in a sample preparation mold. (See [reference]). Figure 5The sample to be tested is located inside an envelope formed by four non-parallel triangular prisms, the axes of which are not parallel. First, acrylic resin with a volume average equivalent atomic number exceeding 50% of the difference between the volume average equivalent atomic number of the sample and the cone was selected as the curable adhesive material. 8g of acrylic resin and 10g of acrylic powder were mixed and poured into a mold, then allowed to cure for 50 minutes at room temperature to obtain the composite sample. After cutting the sample with a grinding wheel, the cross-section of the composite sample was progressively sanded using 240#, 600#, 800#, and 1000# sandpaper, followed by polishing to obtain a smooth and glossy cross-section of the sample. Backscattered images of the cross-section were then taken using a scanning electron microscope. By controlling the polishing material, polishing force, and polishing time, the thickness of each polishing step was ensured to not exceed 1 / 10 of the minimum feature of the surface undulations in the direction parallel to the coating surface. Import the acquired composite specimen cross-section photos into Photoshop software, move the triangular prism cross-sections of each composite specimen cross-section to place them inside the pre-drawn triangular prisms to determine the positional relationship of each triangular prism cross-section, and the positional relationship of each cross-section of the composite specimen is thus determined; extract the two-dimensional morphology curves of different positions of the sprayed coating sample in the cross-section of the composite specimen, import them into Solidworks software, place them according to the positional relationship of each cross-section, and obtain the three-dimensional morphology features of the sprayed coating sample to be tested.

[0053] This invention obtains a composite sample by placing the sample of the sprayed coating to be tested inside an envelope formed by at least three small pillars. During polishing of the composite sample, the polishing material, polishing force, and polishing time are controlled so that the thickness of each polishing pass does not exceed 1 / 10 of the minimum feature of the surface undulations in the direction parallel to the upper surface of the sprayed coating, thereby maximizing the acquisition of the three-dimensional surface morphology features of the coating. Furthermore, the positional relationship of each small pillar cross-section after each polishing pass is determined by moving the cross-section of the small pillars within the composite sample, thus obtaining the actual position of the cross-section of the sprayed coating sample after each polishing pass.

[0054] 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 method for accurately obtaining the three-dimensional surface morphology of a sprayed coating, characterized in that, Please follow these steps: Step 1: Place the spray coating sample to be tested and at least three small pillars in the sample preparation mold, with the spray coating sample to be tested located inside the envelope formed by the small pillars; Step 2: Curing the sprayed coating sample and the small column to be tested to obtain the combined sample; Step 3: Polish the combined sample obtained in Step 2 to obtain a smooth and bright cross-section of the sprayed coating sample to be tested, and photograph the cross-section of the sprayed coating sample to be tested. Step 4: Repeat the operation of Step 3, with the thickness of each polishing not exceeding 1 / 10 of the minimum feature of the surface undulation in the direction parallel to the upper surface of the coating to be tested; Step 5: Import the photos of all the cross-sections of the sprayed coating samples to be tested into software with image reading and drawing functions, extract the cross-sectional features of the combined sample, and determine the positional relationship of each cross-section of the combined sample. Step 6: Extract the two-dimensional morphology curves of different positions of the sprayed coating sample in each cross section of the combined sample, import them into the software for constructing three-dimensional morphology, place them according to the positional relationship determined in Step 5, and obtain the three-dimensional morphology features of the sprayed coating sample to be tested.

2. The method for accurately obtaining the three-dimensional surface morphology of a sprayed coating according to claim 1, characterized in that, In step one, when the cross-sectional shapes of the small columns are the same, the axes of the small columns are not parallel to each other when they are placed.

3. The method for accurately obtaining the three-dimensional surface morphology of a sprayed coating according to claim 1, characterized in that, In step two, the specific steps for curing are as follows: add curable adhesive and acrylic powder into the sample preparation mold, and then cure the sprayed coating sample and the small column to be tested.

4. The method for accurately obtaining the three-dimensional surface morphology of a sprayed coating according to claim 3, characterized in that, The volume average equivalent atomic number of the curable adhesive differs from that of the test spray coating sample and the small column by more than 50%.

5. The method for accurately obtaining the three-dimensional surface morphology of a sprayed coating according to claim 3, characterized in that, Add curable adhesive and acrylic powder in a mass ratio of 4:

5.

6. The method for accurately obtaining the three-dimensional surface morphology of a sprayed coating according to claim 3, characterized in that, The curable adhesive is any one of epoxy resin, acrylic resin, and polyester resin.

7. The method for accurately obtaining the three-dimensional surface morphology of a sprayed coating according to claim 3, characterized in that, The curing time is 30 to 60 minutes.

8. A method for accurately obtaining the three-dimensional surface morphology of a sprayed coating according to any one of claims 1 to 7, characterized in that, In steps three and four, the cross-section of the sprayed coating sample under test is captured by scanning electron microscopy in backscatter mode.

9. A method for accurately obtaining the three-dimensional surface morphology of a sprayed coating according to any one of claims 1 to 7, characterized in that, In step four, the polishing material, polishing force, and polishing time are controlled to ensure that the thickness of each polishing operation does not exceed 1 / 10 of the minimum feature of the surface undulations in the direction parallel to the upper surface of the coating to be tested.

10. A method for accurately obtaining the three-dimensional surface morphology of a sprayed coating according to any one of claims 1 to 7, characterized in that, The specific steps of step five are as follows: import the extracted cross-sectional features of the combined specimen into software with image reading and drawing functions, move the small column cross-sections in each cross-section of the combined specimen, place the small column cross-sections inside the pre-drawn small columns, and obtain the positional relationship of the small column cross-sections; then, through the determined positional relationship of the small column cross-sections in the combined specimen, obtain the positional relationship of each cross-section in the combined specimen.

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