A method for accurately obtaining two-dimensional curves of the surface morphology of a sprayed coating

Abstract

This invention discloses a method for accurately obtaining a two-dimensional curve of the surface morphology of a sprayed coating, belonging to the field of coating surface treatment technology. First, a protective layer is prepared on the surface of the sprayed coating sample to be tested, obtaining the sample. Then, the sample is cut, and the cut sample cross-section is polished, coated with adhesive, and polished to obtain a smooth and bright cross-section. Finally, the smooth and bright cross-section is backscattered and photographed using a scanning electron microscope to obtain a cross-sectional image. The cross-sectional image is imported into finite element simulation software to obtain the two-dimensional curve of the surface morphology of the sprayed coating to be tested. This method can accurately reveal the surface of the sprayed coating to be tested as the interface between the low-brightness area of ​​the sprayed coating and the high-brightness area of ​​the metal coating or metal plating, avoiding the influence of coating collapse and fragmentation on obtaining a complete and accurate surface morphology when directly obtaining the surface morphology of the sprayed coating, and accurately obtaining the two-dimensional surface morphology curve of the true coating.

Description

Technical Field

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

[0002] Coatings effectively prevent the working medium from directly contacting the substrate, providing excellent protection. However, coatings prepared using thermal spraying methods often have rough, uneven surfaces, leading to significant stress concentrations and potentially causing cracking or premature failure. Therefore, researching the influence of coating surface morphology on stress evolution and failure behavior during service is crucial for understanding coating failure mechanisms, optimizing coating structure design, and extending coating service life. While experimental studies cannot reveal the failure process of coatings in service environments, finite element analysis (FEM) calculations using coating models with realistic surface morphology can simulate stress distribution and failure behavior during service.

[0003] Currently, two-dimensional coating models are mainly established using artificially assumed semi-circular or sinusoidal morphologies, or directly depicted surface morphologies of sprayed coatings with collapse and defects. Coating models established using assumed semi-circular and sinusoidal morphologies are too idealized and cannot demonstrate the stress evolution and failure behavior of coatings under realistic morphologies. Coating models established using directly depicted surface morphologies of sprayed coatings with collapse and defects also include surface defects that are not inherent to the coating itself, and therefore cannot accurately simulate the coating failure process.

[0004] To overcome the above problems, it is necessary to obtain accurate true morphology of the coating surface. However, how to accurately obtain the two-dimensional surface morphology curve of the true coating remains a current technical challenge. Summary of the Invention

[0005] In order to overcome the shortcomings of the prior art, the present invention aims to provide a method for accurately obtaining two-dimensional curves of the surface morphology of sprayed coatings, thereby solving the problem that the existing technology, which uses artificially assumed semi-circular morphology, sinusoidal morphology, or directly depicted surface morphology of the sprayed coating with coating collapse and defects to establish a two-dimensional coating model, cannot accurately simulate the coating failure process.

[0006] To achieve the above objectives, the present invention employs the following technical solution:

[0007] This invention discloses a method for accurately obtaining two-dimensional curves of the surface morphology of a sprayed coating, comprising the following steps:

[0008] Step 1: Prepare a protective layer on the surface of the sprayed coating sample to be tested, and obtain the sample;

[0009] Step 2: Cut the sample obtained in Step 1, and grind, apply adhesive, and polish the cut sample cross-section to obtain a smooth and bright cross-section.

[0010] Step 3: Take a backscatter photograph of the smooth and bright cross section obtained in Step 2 using a scanning electron microscope to obtain a cross section photograph; import the cross section photograph into the finite element simulation software to obtain a two-dimensional curve of the surface morphology of the coating to be tested.

[0011] Preferably, in step 1, the protective layer is a metal plating and coating, or a metal coating.

[0012] More preferably, the metal is nickel.

[0013] More preferably, the difference in volume average equivalent atomic number between the metal plating and the metal coating exceeds 30% of that between the coating to be tested.

[0014] Preferably, when the protective layer is a metal plating or coating, the surface of the metal plating has the same hardness as or is 1 / 2 higher than the surface hardness of the sprayed coating sample.

[0015] Preferably, when the protective layer is a metal plating or coating, the thickness of the metal plating is 0.1 to 2 μm.

[0016] Preferably, when the protective layer is a metal plating or coating, the metal plating is obtained by chemical plating, magnetron sputtering, or electroplating.

[0017] Preferably, when the protective layer is a metal plating or coating, the thickness of the coating is 30–200 μm.

[0018] Preferably, when the protective layer is a metal coating, the thickness of the metal coating is ≥20μm.

[0019] Preferably, in step 2, the cross-section of the cut sample is ground to a roughness of ≤20μm.

[0020] Preferably, in step 2, the polishing process is carried out by controlling the polishing material, polishing force, and polishing time, so that the thickness removed by polishing is less than 2 / 3 of the thickness of adhesive penetration.

[0021] Preferably, in step 2, the adhesive diffusion step is as follows: First, the sample of the sprayed coating to be tested is placed in the adhesive diffusion mold, and a vacuum is drawn until the pressure is below 0.01 MPa; then, liquid adhesive is poured into the vacuumed adhesive diffusion mold, and after the liquid adhesive completely covers the sample of the sprayed coating to be tested or completely covers the cross section of the sprayed coating to be tested, the vacuum is released, and the liquid adhesive is pressed into the pores of the coating cross section; finally, the sample is left to stand for 2 to 4 hours to fully remove the gas in the adhesive and then cure, thus completing the adhesive diffusion.

[0022] Preferably, in step 3, if the size of the scale in the cross-sectional photograph changes in the finite element simulation software, the size of the scale is adjusted to the actual size proportionally.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] This invention provides a method for accurately obtaining two-dimensional surface morphology curves of sprayed coatings. A protective layer is prepared on the surface of the sprayed coating sample to be tested, accurately revealing the surface of the coating as the interface between the low-brightness area of ​​the sprayed coating and the high-brightness area of ​​the metal plating or metal coating. This avoids the influence of coating collapse and fragmentation on obtaining a complete and accurate surface morphology when directly acquiring the surface morphology, thus accurately obtaining the two-dimensional surface morphology curve of the true coating. This method simulates the failure behavior of the coating under actual service conditions by establishing a model that reflects the true surface morphology of the coating, thereby improving the coating failure mechanism, guiding coating structure optimization, and extending the service life of the coating.

[0025] Furthermore, a coating layer is sprayed onto the surface of the metal coating. The thin metal coating layer located between the coating layer to be tested and the coating layer can make the surface morphology of the coating layer to be tested visible and prevent the surface of the coating layer to be tested and the metal coating layer from peeling off during polishing.

[0026] Furthermore, the hardness of the coating sprayed on the surface of the metal plating is the same as the surface hardness of the coating to be tested, which can prevent the metal plating from peeling off during polishing.

[0027] Furthermore, the thickness of the metal coating is 0.1–2 μm, and the thickness of the metal coating is ≥20 μm. That is, there is a certain thickness between the sprayed layer to be tested and the coating, or the metal coating has a certain thickness, so that the interface between the sprayed layer to be tested and the protective layer is clearly visible, that is, the surface of the sprayed layer to be tested is clearly visible. Attached Figure Description

[0028] Figure 1 A schematic diagram of the surface morphology of the sprayed coating under test as revealed by the metal coating;

[0029] Figure 2 This is a schematic diagram of the surface morphology of the sprayed coating under test as revealed by the metal coating. Detailed Implementation

[0030] 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.

[0031] 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.

[0032] In this invention, the volume average equivalent atomic number is calculated as follows: volume average equivalent atomic number = equivalent atomic number / density. The equivalent atomic number is obtained by weighted averaging of the atomic numbers of each atom by molar ratio.

[0033] Example 1

[0034] The method for accurately obtaining the two-dimensional curve of the surface morphology of the sprayed coating in this embodiment includes the following steps:

[0035] (1) Preparation of nickel plating

[0036] First, based on the calculation method of volume average equivalent atomic number, metallic nickel with a volume average equivalent atomic number exceeding 30% of the sample material to be tested was selected as the metal plating material in the protective layer. Then, lactic acid, sodium carbonate, sodium hypophosphite, and nickel sulfate were mixed in a mass ratio of 8:1:12:8, and water was added to a volume of 3L. Next, 27mL of ammonia and boric acid (half the mass of sodium carbonate) were added. The sample to be tested was placed in the prepared mixed solution. After the coating surface turned black, it was removed, rinsed three times with water, and dried. The thickness of the nickel layer after plating was 0.1μm. Then, a 30μm thick coating with the same surface material as the sample to be tested was sprayed onto the nickel plating surface.

[0037] (2) Polishing

[0038] After cutting the sample with a grinding wheel, the sample cross-section was polished step by step with 240# and 600# sandpaper. The roughness of the sample cross-section after polishing was 20μm.

[0039] (3) Adhesive Infiltration Treatment

[0040] The sample after polishing was treated with adhesive by negative pressure adsorption. The sample was placed in an adhesive adsorption mold, and then a vacuum was drawn to a pressure of 0.008 MPa. Liquid adhesive was poured into the vacuumed adhesive adsorption mold. After the adhesive completely wrapped the coated sample or completely covered the coating cross section, the vacuum was released and the liquid adhesive was pressed into the pores of the coating cross section. The sample was left to stand for 2 hours to fully remove the gas in the adhesive and then cured, completing the adhesive adsorption treatment. The adhesive penetration thickness was 50 μm.

[0041] (4) Light polishing

[0042] The sample after resin impregnation was lightly polished. By controlling the polishing material, polishing force and polishing time, the thickness was removed by 30μm, resulting in a smooth and bright cross section.

[0043] (5) Taking photos

[0044] Reference Figure 1 A cross-sectional image of the sample is obtained by backscattering photography using a scanning electron microscope, which accurately reveals the interface between the low-brightness area of ​​the coating and the high-brightness area of ​​the nickel plating on the surface of the test coating.

[0045] (6) Two-dimensional curve depiction of coating surface morphology

[0046] Import the photograph into the ABAQUS finite element simulation software, and use spline curves to plot the two-dimensional curve of the surface morphology of the sprayed coating. If the size of the scale in the cross-sectional photograph changes in the finite element simulation software, adjust the size of the scale to the actual size according to the scale to obtain accurate surface morphology dimensions.

[0047] Example 2

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

[0049] (1) Preparation of nickel plating

[0050] First, based on the calculation method of volume average equivalent atomic number, metallic nickel with a volume average equivalent atomic number exceeding 30% of the sample material to be tested was selected as the metal plating material in the protective layer. Then, the nickel-plated sample was pretreated and cleaned with alcohol, dried at 80℃ for 1 hour. The sample and the nickel target were placed in a vacuum magnetron sputtering coating machine, with the sample at a 10° angle to the target. Nickel was plated onto the dried sample surface using vacuum magnetron sputtering, resulting in a nickel layer thickness of 1.2 μm. Finally, a 100 μm thick coating with the same hardness as the sample material to be tested was sprayed onto the nickel layer surface.

[0051] (2) Polishing

[0052] After cutting the sample with a grinding wheel, the sample cross-section was polished step by step with 240#, 600# and 800# sandpaper. The roughness of the sample cross-section after polishing was 12μm.

[0053] (3) Adhesive Infiltration Treatment

[0054] The sample after polishing was treated with adhesive by negative pressure adsorption. The sample was placed in an adhesive adsorption mold, and then a vacuum was drawn to a pressure of 0.006 MPa. Liquid adhesive was poured into the vacuumed adhesive adsorption mold. After the adhesive completely wrapped the coated sample or completely covered the coating cross section, the vacuum was released and the liquid adhesive was pressed into the pores of the coating cross section. The sample was left to stand for 3 hours to fully remove the gas in the adhesive and then cured, completing the adhesive adsorption treatment. The adhesive penetration thickness was 60 μm.

[0055] (4) Light polishing

[0056] The sample after resin impregnation was lightly polished. By controlling the polishing material, polishing force and polishing time, the thickness was removed by 38μm, resulting in a smooth and bright cross section.

[0057] (5) Taking photos

[0058] Reference Figure 1 A cross-sectional image of the sample is obtained by backscattering photography using a scanning electron microscope, which accurately reveals the interface between the low-brightness area of ​​the coating and the high-brightness area of ​​the nickel plating on the surface of the test coating.

[0059] (6) Two-dimensional curve depiction of coating surface morphology

[0060] Import the photograph into the ABAQUS finite element simulation software, and use spline curves to plot the two-dimensional curve of the surface morphology of the sprayed coating. If the size of the scale in the cross-sectional photograph changes in the finite element simulation software, adjust the size of the scale to the actual size according to the scale to obtain accurate surface morphology dimensions.

[0061] Example 3

[0062] The method for accurately obtaining the two-dimensional curve of the surface morphology of the sprayed coating in this embodiment includes the following steps:

[0063] (1) Preparation of nickel plating

[0064] First, based on the calculation method of volume average equivalent atomic number, metallic nickel with a volume average equivalent atomic number exceeding 30% of the sample material to be tested was selected as the metal plating material in the protective layer. The sample to be tested was used as the cathode, and a pure nickel plate was used as the anode. The sample was immersed in an electrolyte prepared with a mass ratio of nickel sulfate, nickel chloride, and boric acid of 5:1:1. Electroplating was carried out for 100 minutes under the conditions of 10V voltage and 70A current. The thickness of the nickel layer after plating was 2μm. Then, a coating with a thickness of 200μm and a hardness 1 / 2 higher than that of the surface layer of the sample to be tested was sprayed onto the nickel layer.

[0065] (2) Polishing

[0066] After cutting the sample with a grinding wheel, the sample cross-section was polished step by step using 240#, 600#, 800#, and 1000# sandpaper. The roughness of the sample cross-section after polishing was 7μm.

[0067] (3) Adhesive Infiltration Treatment

[0068] The polished sample was treated with adhesive by negative pressure adsorption. The sample was placed in an adhesive adsorption mold, and then a vacuum was drawn to a pressure of 0.004 MPa. Liquid adhesive was poured into the vacuumed adhesive adsorption mold. After the adhesive completely wrapped the coated sample or completely covered the coating cross section, the vacuum was released and the liquid adhesive was pressed into the pores of the coating cross section. The sample was left to stand for 4 hours to fully remove the gas in the adhesive and then cured, completing the adhesive adsorption treatment. The adhesive penetration thickness was 70 μm.

[0069] (4) Light polishing

[0070] The sample after resin impregnation was lightly polished. By controlling the polishing material, polishing force and polishing time, the thickness was removed by 40μm, resulting in a smooth and bright cross section.

[0071] (5) Taking photos

[0072] Reference Figure 1 A cross-sectional image of the sample is obtained by backscattering photography using a scanning electron microscope, which accurately reveals the interface between the low-brightness area of ​​the coating and the high-brightness area of ​​the nickel plating on the surface of the test coating.

[0073] (6) Two-dimensional curve depiction of coating surface morphology

[0074] Import the photograph into the ABAQUS finite element simulation software, and use spline curves to plot the two-dimensional curve of the surface morphology of the sprayed coating. If the size of the scale in the cross-sectional photograph changes in the finite element simulation software, adjust the size of the scale to the actual size according to the scale to obtain accurate surface morphology dimensions.

[0075] Example 4

[0076] The method for accurately obtaining the two-dimensional curve of the surface morphology of the sprayed coating in this embodiment includes the following steps:

[0077] (1) Preparation of nickel coating

[0078] First, based on the calculation method of volume average equivalent atomic number, metallic nickel with a volume average equivalent atomic number exceeding 30% of the sample material to be tested was selected as the metal coating material. A nickel coating with a thickness of 20 μm was prepared by spraying on the surface of the sample material to be tested using a supersonic flame spraying device. The nickel powder particle size was 50-100 μm. During spraying, the kerosene flow rate was 20-30 L / h, the oxygen flow rate was 800-900 L / min, the spraying distance was 280-320 mm, and the spray gun moving speed was 800-1000 mm / min.

[0079] (2) Polishing

[0080] After cutting the sample with a grinding wheel, the sample cross-section was polished step by step with 240# and 600# sandpaper. The roughness of the sample cross-section after polishing was 20μm.

[0081] (3) Adhesive Infiltration Treatment

[0082] The sample after polishing was treated with adhesive by negative pressure adsorption. The sample was placed in an adhesive adsorption mold, and then a vacuum was drawn to a pressure of 0.008 MPa. Liquid adhesive was poured into the vacuumed adhesive adsorption mold. After the adhesive completely wrapped the coated sample or completely covered the coating cross section, the vacuum was released and the liquid adhesive was pressed into the pores of the coating cross section. The sample was left to stand for 2 hours to fully remove the gas in the adhesive and then cured, completing the adhesive adsorption treatment. The adhesive penetration thickness was 50 μm.

[0083] (4) Light polishing

[0084] The sample after resin impregnation was lightly polished. By controlling the polishing material, polishing force and polishing time, the thickness was removed by 30μm, resulting in a smooth and bright cross section.

[0085] (5) Taking photos

[0086] Reference Figure 2 A cross-sectional image of the sample is obtained by backscattering photography using a scanning electron microscope, which accurately reveals the interface between the low-brightness area of ​​the coating and the high-brightness area of ​​the nickel plating on the surface of the test coating.

[0087] (6) Two-dimensional curve depiction of coating surface morphology

[0088] Import the photograph into the ABAQUS finite element simulation software, and use spline curves to plot the two-dimensional curve of the surface morphology of the sprayed coating. If the size of the scale in the cross-sectional photograph changes in the finite element simulation software, adjust the size of the scale to the actual size according to the scale to obtain accurate surface morphology dimensions.

[0089] Example 5

[0090] The method for accurately obtaining the two-dimensional curve of the surface morphology of the sprayed coating in this embodiment includes the following steps:

[0091] (1) Preparation of nickel coating

[0092] First, based on the calculation method of volume average equivalent atomic number, metallic nickel with a volume average equivalent atomic number exceeding 30% of the sample material to be tested was selected as the metal coating material. An atmospheric plasma spraying equipment was used to spray a nickel coating with a thickness of 150 μm onto the surface of the sample to be tested. The nickel powder particle size was 50-100 μm. Argon was used as the protective gas during spraying, with a protective gas flow rate of 40-50 L / min, a spraying distance of 220-250 mm, and a spray gun moving speed of 800-1000 mm / min.

[0093] (2) Polishing

[0094] After cutting the sample with a grinding wheel, the sample cross-section was polished step by step with 240#, 600# and 800# sandpaper. The roughness of the sample cross-section after polishing was 12μm.

[0095] (3) Adhesive Infiltration Treatment

[0096] The sample after polishing was treated with adhesive by negative pressure adsorption. The sample was placed in an adhesive adsorption mold, and then a vacuum was drawn to a pressure of 0.006 MPa. Liquid adhesive was poured into the vacuumed adhesive adsorption mold. After the adhesive completely wrapped the coated sample or completely covered the coating cross section, the vacuum was released and the liquid adhesive was pressed into the pores of the coating cross section. The sample was left to stand for 3 hours to fully remove the gas in the adhesive and then cured, completing the adhesive adsorption treatment. The adhesive penetration thickness was 60 μm.

[0097] (4) Light polishing

[0098] The sample after resin impregnation was lightly polished. By controlling the polishing material, polishing force and polishing time, the thickness was removed by 38μm, resulting in a smooth and bright cross section.

[0099] (5) Taking photos

[0100] Reference Figure 2 A cross-sectional image of the sample is obtained by backscattering photography using a scanning electron microscope, which accurately reveals the interface between the low-brightness area of ​​the coating and the high-brightness area of ​​the nickel plating on the surface of the test coating.

[0101] (6) Two-dimensional curve depiction of coating surface morphology

[0102] Import the photograph into the ABAQUS finite element simulation software, and use spline curves to plot the two-dimensional curve of the surface morphology of the sprayed coating. If the size of the scale in the cross-sectional photograph changes in the finite element simulation software, adjust the size of the scale to the actual size according to the scale to obtain accurate surface morphology dimensions.

[0103] This invention prepares a protective layer on the surface of the sprayed coating sample with a volume average equivalent atomic number exceeding 30% of the sprayed coating. This allows the surface of the sprayed coating to be accurately revealed in the form of the interface between the low-brightness area of ​​the coating and the high-brightness area of ​​the protective layer, avoiding the influence of coating collapse and fragmentation on obtaining a complete and accurate surface morphology when directly acquiring the surface morphology of the sprayed coating.

[0104] 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 a two-dimensional curve of a surface profile of a sprayed layer, characterized in that, The method comprises the following steps: Step 1, preparing a protective layer on the surface of the sample to be tested, to obtain a sample; The protective layer is a metal plating layer with a thickness of 0.1-2 μm and a coating layer with a thickness of 30-200 μm, or a metal coating layer with a thickness of ≥20 μm; the volume average equivalent atomic number difference of the metal plating layer and the metal coating layer is more than 30% of the sample to be tested; when the protective layer is a metal plating layer and a coating layer, the coating layer on the surface of the metal plating layer has the same hardness as the surface layer of the sample to be tested or is 1 / 2 higher than the hardness of the surface layer of the sample to be tested; Step 2, cutting the sample obtained in step 1, and sequentially polishing, impregnating and polishing the cut sample section to obtain a smooth and bright section; The polishing is performed by controlling the polishing material, polishing force and polishing time, so that the polishing removal thickness is less than 2 / 3 of the impregnation thickness; the impregnation step is as follows: first, place the sample to be tested in an impregnation mold, and vacuumize to a pressure lower than 0.01 MPa; then pour the liquid glue into the vacuumized impregnation mold, and after the liquid glue completely wraps the sample to be tested and completely covers the section of the sample to be tested, release the vacuum to press the liquid glue into the pores of the coating section; finally, let the sample stand for 2-4 h, and after the gas in the glue is fully removed, solidify to complete the impregnation; Step 3, taking a backscattering photograph of the smooth and bright section obtained in step 2 by a scanning electron microscope to obtain a section photograph; importing the section photograph into a finite element simulation software to obtain a two-dimensional curve of the surface morphology of the sample to be tested.

2. The method of claim 1, wherein, When the protective layer is a metal plating layer and a coating layer, the metal plating layer is obtained by chemical plating, magnetron sputtering or electroplating.

3. The method for accurately obtaining a two-dimensional curve of a surface profile of a sprayed layer according to claim 1 or 2, characterized in that, In step 2, the cut sample section is polished to a roughness of ≤20 μm.

4. The method for accurately obtaining a two-dimensional curve of a surface profile of a sprayed layer according to claim 1 or 2, characterized in that, In step 3, if the size of the scale of the section photograph changes in the finite element simulation software, the size of the scale is adjusted to the actual size in proportion.

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