Preparation method of metallographic specimen for sealing part of flange with ceramic coating

Abstract

The invention relates to the field of preparation of a metallographic specimen for a sealing part of a flange with a ceramic coating, and provides a preparation method of a metallographic specimen for a sealing part of a flange with a ceramic coating. The flange with the ceramic coating is installed on a machining center, and the diamond grinding head conducts machining along the scribing position to form a coating-free area; processing along the uncoated area to form a blocky sample with a ceramic coating; processing and cutting downwards along the distance from the surface of the ceramic coating to form a blocky sample with the ceramic coating; removing a coating-free area and then removing a heat-affected area to form a blocky sample with a ceramic coating; carrying out rough grinding treatment and then carrying out fine grinding treatment to form the metallographic specimen with the ceramic coating. According to the preparation method of the metallographic specimen for the sealing part of the flange with the ceramic coating, the difficulty is low, the prepared metallographic specimen with the ceramic coating is low in section roughness and free of defects such as damage, scratches and cracks, and the quality of the ceramic coating thermally sprayed on the surface of a product can be effectively reflected.

Description

Technical Field

[0001] The invention relates to the field of metallographic sample preparation of a sealing part of a flange with a ceramic coating, and in particular to a method for preparing a metallographic sample of a sealing part of a flange with a ceramic coating. Background Art

[0002] By testing the metallographic morphology of the ceramic coating cross section, the density and composition uniformity of the ceramic coating product can be directly reflected, and the quality stability of the ceramic coating of this batch of products can be determined. However, the ceramic coating has the characteristics of high hardness, high brittleness, strong insulation, and a bonding strength between 20 and 30 MPa. When the ceramic coating on the surface of the flange product is sampled by traditional wire cutting, turning, grinding and other processing methods, it is very easy to cause the ceramic coating to collapse, crack, delamination and other problems, making it difficult for subsequent metallographic tests to effectively reflect the coating quality.

[0003] In the article "Thermal Spray Coating Machining Technology and Application" in Volume 52 of "Tool Technology" in 2018, it is summarized that the post-processing of thermal spray coatings has the problem of easy peeling and edge collapse of the coating. In the article "Microstructure Detection Technology of Plasma Sprayed Al2O3 Ceramic Coating" in the fourth issue of "Metal Heat Treatment" in 2021, Jie Qing used resin-bonded SiC wet grinding wheel cutting discs; when inlaying, the epoxy resin vacuum infiltration cold inlay method was used, and metallographic sample preparation was performed on the surface of the sample-level ceramic coating. Based on automated metallographic grinding and polishing equipment, SiC sandpaper grinding, and polishing with a low-elasticity hairless polishing cloth, and equipped with correct test parameters, it can effectively prevent the occurrence of problems such as edge collapse of the ceramic coating during the metallographic sample preparation process.

[0004] The patent application number CN201921781191.4 in the prior art discloses a coating processing device for flange surface of ship pipe fittings, including a fixing component and a construction component. The fixing component has a special-shaped top plate, and three legs are connected below the special-shaped top plate. A clamp is fixed on the legs, and a first circular hole is opened in the center of the special-shaped top plate. The construction component includes a control component and a processing component. The control component has an internal threaded component, which is fixed below the first circular hole. An external threaded component is arranged inside the internal threaded component. The central axis passes through the external threaded component and is movably connected to the external threaded component. A cover plate is arranged on the external threaded component, and the central axis passes through the cover plate, and the external threaded component is fixedly connected to the cover plate. The processing component has a cross-shaped bottom plate, a round tube is vertically fixed in the center of the bottom plate, a milling cutter is fixed at each end of the long side of the cross-shaped bottom plate, and the bottom end of the central axis is inserted into the round tube and fixedly connected to the round tube. Although this patent can use milling to perform on-site processing of polyethylene anti-corrosion coatings on flange surfaces to observe the morphology of soft organic polymer coatings, milling is difficult for thermal sprayed ceramic coatings with higher hardness and is prone to causing "edge collapse" and cracking, and cannot effectively reflect the quality of thermal sprayed ceramic coatings on the product surface.

[0005] In view of this, the present invention is proposed. Summary of the invention

[0006] The purpose of the present invention is to propose a method for preparing metallographic samples of the sealing part of a flange with a ceramic coating, so as to solve the problem that in the prior art, the milling of thermally sprayed ceramic coatings with higher hardness is difficult and easy to cause "edge collapse" and cracking, and cannot effectively reflect the quality of the thermally sprayed ceramic coating on the surface of the product.

[0007] To achieve the above object, the technical solution of the present invention is achieved as follows:

[0008] A method for preparing a metallographic sample of a sealing part of a flange with a ceramic coating, the method comprising the following steps:

[0009] S1. Mark the processing area on the surface of the ceramic coated flange;

[0010] S2. Install the ceramic-coated flange on the machining center and align it; install a 100-mesh cylindrical diamond grinding head with a size of φ4mm*10mm, and make the diamond grinding head process along the scribed position until the ceramic coating at the scribed position is completely removed to form a non-coated area with a width of 4mm;

[0011] S3. Install the flange in the coating area where the coating is marked on the wire cutting equipment, and process along the uncoated area with a width of 4 mm. The distance between the processing position and the ceramic coating is ≥ 2 mm to form a block sample with ceramic coating;

[0012] S4, mounting the block sample obtained in step S3 on an online cutting device, and cutting the block sample at a position ≥8 mm downward from the surface of the ceramic coating to form a block sample with a ceramic coating;

[0013] S5, installing the block sample with ceramic coating obtained in step S4 on a machining center and aligning it; carrying out the diamond grinding head, first removing the uncoated area, then removing the heat-affected area, and machining inward 1.5 to 2.5 mm to form a block sample with ceramic coating;

[0014] S6. A resin grinding wheel is mounted on a machining center to perform a rough grinding process on the cross section of the block sample with ceramic coating obtained in step S5, and then perform a fine grinding process to form a metallographic sample with ceramic coating.

[0015] In the method for preparing a metallographic sample of a sealing part of a flange with a ceramic coating described in the present invention, steps S1 to S6 are interrelated and play multiple roles together: first, the difficulty of preparing a metallographic sample with a ceramic coating is reduced; second, the cross-sectional roughness of the prepared metallographic sample with a ceramic coating is low; third, the cross-sectional area of ​​the prepared metallographic sample with a ceramic coating is not interfered by the heat-affected zone of wireless cutting, and is free of defects such as damage, scratches, and cracks, and can effectively reflect the quality of the thermally sprayed ceramic coating on the surface of the product.

[0016] Furthermore, in step S2, the grinding head rotation speed is 4000-6000 r / min, the grinding head moving speed is 25-35 mm / min, and the cutting amount each time is 0.03-0.05 mm.

[0017] Furthermore, in step S3, a 0.18 mm φ molybdenum wire for wire cutting is used, and the wire cutting speed is 3000-4000 mm / mm. 2 .

[0018] Furthermore, in step S4, a φ0.18 mm molybdenum wire specially used for wire cutting is used, and the wire cutting speed is 3000-4000 mm / mm2.

[0019] Furthermore, in step S5, a φ100 mm 80-mesh bowl-shaped diamond grinding head is mounted on the machining center.

[0020] Furthermore, in step S5, when removing the uncoated area, the grinding head rotation speed is 2500-3500 r / min, and the grinding head moving speed is 18-22 mm / min.

[0021] Furthermore, in step S5, when removing the heat affected zone, the grinding head rotation speed is 5000-7000 r / min, and the grinding head moving speed is 8-12 mm / min.

[0022] Furthermore, in step S6, a φ100 mm 80-mesh bowl-shaped resin grinding wheel is mounted on the machining center.

[0023] Furthermore, in step S6, during the rough grinding process, the grinding head rotation speed is 5000-7000 r / min, the grinding head moving speed is 8-12 mm / min, the downward grinding is ≥0.4 mm, and the single downward cutting amount is ≤0.02 mm.

[0024] Furthermore, in step S6, during fine grinding, the grinding head rotation speed is 5000-7000 r / min, the grinding head moving speed is 8-12 mm / min, and the single cutting amount is ≤0.005 mm.

[0025] The present invention proposes a method for preparing a metallographic sample of a sealing part of a flange with a ceramic coating. Compared with the prior art, the method for preparing a metallographic sample of a sealing part of a flange with a ceramic coating according to the present invention has the following beneficial effects:

[0026] 1) The method for preparing a metallographic sample of a flange sealing part with a ceramic coating described in the present invention has a low cross-sectional roughness, no interference from the heat-affected zone of wireless cutting, and no defects such as damage, scratches, and cracks. The sample processed at the flange sealing part is observed and analyzed using a metallographic microscope, which can intuitively determine the density and uniformity of this batch of ceramic coating products, thereby ensuring that the quality of the coating products is stable and reliable.

[0027] 2) The method for preparing metallographic samples of the sealing parts of flanges with ceramic coatings described in the present invention effectively solves the problem that the density of thermal sprayed ceramic coatings cannot be detected, ensures the quality stability of thermal sprayed ceramic coating products, and has broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is one of the metallographic morphology images of a metallographic sample of a sealing part of a flange with a ceramic coating as described in Example 1 of the present invention;

[0029] Figure 2 This is the second metallographic morphology image of a metallographic sample of a sealing part of a flange with a ceramic coating as described in Example 1 of the present invention;

[0030] Figure 3 The third metallographic morphology diagram of the metallographic sample of the sealing part of the flange with ceramic coating described in Example 1 of the present invention;

[0031] Figure 4 This is the fourth metallographic morphology diagram of the metallographic sample of the sealing part of the flange with ceramic coating described in Example 1 of the present invention;

[0032] Figure 5 This is one of the metallographic morphology images of a metallographic sample of a sealing part of a flange with a ceramic coating as described in Example 2 of the present invention;

[0033] Figure 6 This is the second metallographic morphology image of a metallographic sample of a sealing part of a flange with a ceramic coating as described in Example 2 of the present invention;

[0034] Figure 7 The third metallographic morphology diagram of a metallographic sample of a sealing part of a flange with a ceramic coating as described in Example 2 of the present invention;

[0035] Figure 8 This is the fourth metallographic morphology diagram of the metallographic sample of the sealing part of the flange with ceramic coating described in Example 2 of the present invention. DETAILED DESCRIPTION

[0036] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other. The descriptions of "first", "second", etc. mentioned in the embodiments of the present invention are only for descriptive purposes, and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In addition, the technical solutions between the various embodiments can be combined with each other, but they must be based on the ability of ordinary technicians in the field to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0037] The present invention will be described in detail below with reference to the accompanying drawings and in conjunction with embodiments.

[0038] Example 1

[0039] In the prior art, it is difficult to mill thermally sprayed ceramic coatings with high hardness and it is easy to cause "edge collapse" and cracking, which cannot effectively reflect the quality problems of thermally sprayed ceramic coatings on the product surface.

[0040] In order to solve the above technical problems, the present invention will provide a method for preparing metallographic samples of the sealing part of the surface of a flange with a ceramic coating. For flange products whose surfaces have been prepared with ceramic coatings, grinders, wire cutting machines, grinding machines and other equipment are used in sequence. By adjusting the process parameters such as the amount of advance in the processing and the speed of the tool, a ceramic coating metallographic sample is successfully cut from the flange sealing part without damaging the ceramic coating in the flange sealing area, thereby accurately evaluating the quality stability of the ceramic coating of this batch of products.

[0041] The problem to be solved by the present invention is the preparation of metallographic samples of the sealing parts of a flange with a ceramic coating.

[0042] The present invention provides a method for preparing a metallographic sample of a sealing part of a flange with a ceramic coating, and the method for preparing a metallographic sample of a sealing part of a flange with a ceramic coating comprises the following steps:

[0043] S1. Mark the processing area on the surface of the DN100 ceramic-coated boss flange;

[0044] In this embodiment, the size of the scribe area is 22×22 mm.

[0045] S2. Install the ceramic-coated flange on the machining center and align it; install a 100-mesh cylindrical diamond grinding head with a size of φ4mm*10mm, and make the diamond grinding head process along the scribed position until the ceramic coating at the scribed position is completely removed to form a non-coated area with a width of 4mm;

[0046] Specifically, wire cutting is a high-temperature process, and direct cutting of the ceramic coating may cause cracks in the ceramic coating; therefore, the ceramic coating must be removed before wire cutting.

[0047] Specifically, in step S2, the grinding head rotation speed is 4000-6000 r / min, the grinding head moving speed is 25-35 mm / min, and the cutting amount each time is 0.03-0.05 mm.

[0048] More specifically, in this embodiment, in step S2, the grinding head rotation speed is 5000 r / min, the grinding head moving speed is 30 mm / min, and the cutting amount each time is 0.05 mm.

[0049] S3. Install the flange with the coated area where the coating is marked on the wire cutting equipment, and process the uncoated area with a width of 4 mm processed in the previous step in the longitudinal direction. The distance between the processing position and the ceramic coating is ≥ 2 mm. Cut the marked area from the flange with ceramic coating to form a block sample with ceramic coating.

[0050] Specifically, in step S3, a 0.18 mm φ molybdenum wire for wire cutting is used, and the wire cutting speed is 3000-4000 mm / mm. 2 .

[0051] More specifically, in this embodiment, in step S3, the distance between the processing position and the ceramic coating is 2 mm, and the wire cutting speed is 3500 mm / mm. 2 .

[0052] S4. Due to the limited space of the metallographic microscope equipment, the block sample with ceramic coating obtained in step S3 needs to be shortened in the transverse direction. The block sample with ceramic coating obtained in step S3 is mounted on the online cutting equipment and processed and cut at a position ≥8 mm downward from the surface of the ceramic coating to form a block sample with ceramic coating;

[0053] Specifically, in step S4, a 0.18 mm φ molybdenum wire for wire cutting is used, and the wire cutting speed is 3000-4000 mm / mm. 2 .

[0054] More specifically, in this embodiment, in step S4, a block sample with a ceramic coating is cut 10 mm below the surface of the ceramic coating, and the wire cutting speed is 3500 mm / mm.2 .

[0055] S5, installing the ceramic coated block sample obtained in step S4 on a machining center and aligning it; carrying out grinding with a diamond grinding head, first removing the uncoated area, and grinding and removing the uncoated area along the cross section of the ceramic coated block sample with the diamond grinding head until the uncoated area at the edge of the coated sample is completely removed; then removing the heat affected area, machining inward 1.5 to 2.5 mm, ensuring that the ceramic coating in the wire cutting heat affected area is completely removed, and forming a ceramic coated block sample;

[0056] In step S5, after the removal of the uncoated area is completed, since the thermal expansion coefficient of the ceramic coating is significantly different from that of the substrate, in order to avoid the influence of the heat input caused by the wire cutting process on the micromorphology of the ceramic coating, such as the generation of cracks and holes, the heat effects that may be caused by wire cutting need to be further removed.

[0057] Specifically, in step S5, a φ100 mm 80-mesh bowl-shaped diamond grinding head is mounted on the machining center.

[0058] Specifically, in step S5, when removing the uncoated area, the grinding head rotation speed is 2500-3500 r / min, and the grinding head moving speed is 18-22 mm / min.

[0059] Specifically, in step S5, when removing the heat affected zone, the grinding head rotation speed is 5000-7000 r / min, and the grinding head moving speed is 8-12 mm / min.

[0060] More specifically, in this embodiment, in step S5, when removing the uncoated area, the grinding head rotation speed is 3000r / min, and the grinding head moving speed is 20mm / min; when removing the heat-affected area, 1.5mm is processed inward, the grinding head rotation speed is 6000r / min, and the grinding head moving speed is 10mm / min.

[0061] S6. After the removal of the uncoated area and the heat-affected area, the ceramic coating on the cross section of the sample is ground and polished until it meets the metallographic observation requirements; a resin grinding wheel is installed in the machining center to first perform a rough grinding treatment on the cross section of the block sample with ceramic coating in step S5 to remove burrs and broken edges formed on the coating cross section in the previous step; and then perform fine grinding. After fine grinding, the roughness is ≤Ra0.4um, forming a metallographic sample with ceramic coating.

[0062] Specifically, in step S6, a φ100 mm 80-mesh bowl-shaped resin grinding wheel is mounted on the machining center.

[0063] Specifically, in step S6, during the rough grinding process, the grinding head rotation speed is 5000-7000 r / min, the grinding head moving speed is 8-12 mm / min, the downward grinding is ≥0.4 mm, and the single downward cutting amount is ≤0.02 mm.

[0064] Specifically, in step S6, during the fine grinding process, the grinding head rotation speed is 5000-7000 r / min, the grinding head moving speed is 8-12 mm / min, and the single cutting amount is ≤0.005 mm.

[0065] More specifically, in this embodiment, in step S6, when rough grinding is performed, the grinding head speed is 6000r / min, the grinding head moving speed is 10mm / min, the grinding is downwardly ground 0.4mm, and the single cutting amount is 0.02mm; when fine grinding is performed, the grinding head speed is 6000r / min, the grinding head moving speed is 10mm / min, and the single cutting amount is 0.005mm.

[0066] In the method for preparing a metallographic sample of a sealing part of a flange with a ceramic coating described in the present invention, steps S1 to S6 are interrelated and play multiple roles together: first, the difficulty of preparing a metallographic sample with a ceramic coating is reduced; second, the cross-sectional roughness of the prepared metallographic sample with a ceramic coating is low; third, the cross-sectional area of ​​the prepared metallographic sample with a ceramic coating is not interfered by the heat-affected zone of wireless cutting, and is free of defects such as damage, scratches, and cracks, and can effectively reflect the quality of the thermally sprayed ceramic coating on the surface of the product.

[0067] Example 2

[0068] In this embodiment, different from Embodiment 1, the boss flange with ceramic coating is a DN40 boss flange with ceramic coating.

[0069] In step S2, the grinding head rotation speed is 4500 r / min, the grinding head moving speed is 35 mm / min, and the cutting amount each time is 0.04 mm.

[0070] In step S3, the wire cutting speed is 4000 mm / mm 2 .

[0071] In step S4, the wire cutting speed is 4000 mm / mm 2 .

[0072] More specifically, in this embodiment, in step S5, when removing the uncoated area, the grinding head rotation speed is 3500r / min, and the grinding head moving speed is 18mm / min; when machining inward 2.0mm to remove the heat-affected area, when machining inward to remove the heat-affected area, the grinding head rotation speed is 7000r / min, and the grinding head moving speed is 12mm / min.

[0073] More specifically, in this embodiment, in step S6, when rough grinding is performed, the grinding head speed is 7000r / min, the grinding head moving speed is 12mm / min, the single cutting amount is 0.01mm, and the downward grinding is 0.5mm; when fine grinding is performed, the grinding head speed is 7000r / min, the grinding head moving speed is 12mm / min, and the single cutting amount is 0.004mm.

[0074] Performance Testing

[0075] The cross-sectional roughness of the metallographic specimens with ceramic coatings processed in Example 1 and Example 2 was measured, and the test results are shown in Table 1. The microscopic morphology of the metallographic specimens with ceramic coatings processed in Example 1 and Example 2 was observed using a 100x metallographic microscope, and the observation results are shown in Table 1. Figures 1 to 8 shown.

[0076] Table 1 Cross-sectional roughness test results of metallographic specimens with ceramic coating after processing in Examples 1 to 2

[0077]

[0078] It can be seen from Table 1 that the roughness of the cross sections of the metallographic specimens with ceramic coatings processed in Example 1 and Example 2 is relatively low, and the roughness is ≤Ra0.4um.

[0079] from Figures 1 to 8 It can be seen that the cross-sections of the metallographic samples with ceramic coating after processing in Example 1 and Example 2 have no interference from the heat affected zone of wireless cutting, and no defects such as processing cracks, edge collapse, breakage, scratches, etc. The sample processed at the flange sealing part is observed and analyzed using a metallographic microscope, which can intuitively judge the density and uniformity of this batch of ceramic coating products, ensuring the stable and reliable quality of the coating products.

[0080] Although the present invention is disclosed as above, the present invention is not limited thereto. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the scope defined by the claims.

Claims

1. A method for preparing metallographic samples of the sealing part of a flange with a ceramic coating, characterized in that: The method for preparing a metallographic sample of a sealing part of a flange with a ceramic coating comprises the following steps: S1. Mark the processing area on the surface of the ceramic coated flange; S2. Install the ceramic-coated flange on the machining center and align it; install a 100-mesh cylindrical diamond grinding head with a size of φ4mm*10mm, and make the diamond grinding head process along the scribed position until the ceramic coating at the scribed position is completely removed to form a non-coated area with a width of 4mm; S3. Install the flange in the coating area where the coating is marked on the wire cutting equipment, and process along the uncoated area with a width of 4 mm. The distance between the processing position and the ceramic coating is ≥ 2 mm to form a block sample with ceramic coating; S4, mounting the block sample obtained in step S3 on an online cutting device, and cutting the block sample at a position ≥8 mm downward from the surface of the ceramic coating to form a block sample with a ceramic coating; S5, installing the block sample with ceramic coating obtained in step S4 on a machining center and aligning it; carrying out the diamond grinding head, first removing the uncoated area, then removing the heat-affected area, and machining inward 1.5 to 2.5 mm to form a block sample with ceramic coating; S6. A resin grinding wheel is mounted on a machining center to perform a rough grinding process on the cross section of the block sample with ceramic coating obtained in step S5, and then perform a fine grinding process to form a metallographic sample with ceramic coating.

2. The method for preparing metallographic samples of the sealing part of a flange with ceramic coating according to claim 1 is characterized in that: In step S2, the grinding head rotation speed is 4000-6000 r / min, the grinding head moving speed is 25-35 mm / min, and the cutting amount each time is 0.03-0.05 mm.

3. The method for preparing metallographic samples of the sealing part of a flange with ceramic coating according to claim 1 is characterized in that: In step S3, a 0.18 mm φ molybdenum wire is used for wire cutting, and the wire cutting speed is 3000-4000 mm / mm. 2 .

4. The method for preparing metallographic samples of sealing parts of flanges with ceramic coatings according to claim 1 is characterized in that: In step S4, a 0.18 mm φ molybdenum wire is used for wire cutting, and the wire cutting speed is 3000-4000 mm / mm. 2 .

5. The method for preparing metallographic samples of sealing parts of flanges with ceramic coatings according to claim 1 is characterized in that: In step S5, a φ100 mm 80-mesh cup-shaped diamond grinding head is mounted on the machining center.

6. The method for preparing metallographic samples of sealing parts of flanges with ceramic coatings according to claim 1 is characterized in that: In step S5, when removing the uncoated area, the grinding head rotation speed is 2500-3500 r / min, and the grinding head moving speed is 18-22 mm / min.

7. The method for preparing metallographic samples of the sealing part of a flange with ceramic coating according to claim 1 is characterized in that: In step S5, when removing the heat affected zone, the grinding head rotation speed is 5000-7000 r / min, and the grinding head moving speed is 8-12 mm / min.

8. The method for preparing metallographic samples of the sealing part of a flange with ceramic coating according to claim 1 is characterized in that: In step S6, a φ100 mm 80-mesh cup-shaped resin grinding wheel is mounted on the machining center.

9. The method for preparing metallographic samples of sealing parts of flanges with ceramic coatings according to claim 1, characterized in that: In step S6, during the rough grinding process, the grinding head rotation speed is 5000-7000 r / min, the grinding head moving speed is 8-12 mm / min, the downward grinding is ≥0.4 mm, and the single downward cutting amount is ≤0.02 mm.

10. The method for preparing metallographic samples of sealing parts of flanges with ceramic coatings according to claim 1, characterized in that: In step S6, during the fine grinding process, the grinding head rotation speed is 5000-7000 r / min, the grinding head moving speed is 8-12 mm / min, and the single cutting amount is ≤0.005 mm.

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