Method for analyzing and representing silicon steel coating by using laser confocal Raman spectrometer

Abstract

The invention discloses a method for analyzing and characterizing a silicon steel coating by using a laser confocal Raman spectrometer, which at least comprises the following steps of: 1, uniformly coating a coating liquid sample to be detected on a high-temperature-resistant glass sheet by using a bar coating device to obtain a sample-coated sheet; step 2, drying the thin sheet coated with the sample obtained in the step 1 in a drying oven to obtain a thin sheet with a dried coating film; and step 3, placing the sheet with the dried coating film obtained in the step 2 on a sample table of a laser confocal Raman spectrometer, and performing focusing, projection and acquisition to obtain a Raman spectrum of the coating to be detected. According to the method, the coating sample is prepared again, so that an effective and analyzable Raman spectrum can be obtained.

Description

Technical Field

[0001] The invention relates to the technical field of silicon steel surface coating detection, and in particular to a method for analyzing and characterizing silicon steel coating using a laser confocal Raman spectrometer. Background Art

[0002] Non-oriented silicon steel sheet is a soft magnetic material and the most widely used alloy among magnetic materials. It is primarily used in the electromechanical industry to manufacture motor cores and other magnetic components, making it an indispensable material for industries such as motor manufacturing, household appliances, and telecommunications instrumentation. To improve equipment efficiency, conserve energy, and effectively limit losses within the steel sheets, an insulating coating is applied to the silicon steel surface. This coating typically exhibits excellent insulation, adhesion, punchability, weldability, heat resistance, and corrosion resistance. Non-oriented silicon steel coatings are primarily classified into three categories: organic, inorganic, and semi-organic. Currently, over 80% of coatings contain chromium. However, the use of chromium-containing coatings during production, application, waste disposal, and processing and use of the coated steel sheets can pose health risks to operators. With increasing environmental awareness and recognition of the serious consequences of chromium-containing coatings for human health and the environment, developed countries such as Europe and the United States have gradually abandoned the use of chromium-containing coatings in silicon steel production, switching to chromium-free, environmentally friendly coatings.

[0003] In summary, it is urgent to develop environmentally friendly coatings to replace chromium-containing coatings, and the detection and characterization technology of coating components also needs to keep pace with the times to adapt to the detection needs of the developed coatings. The laser confocal Raman spectrometer has significant advantages such as high detection resolution, non-destructive, fast, efficient and accurate, and is very suitable for the analysis and characterization of the components of silicon steel surface coatings. However, researchers have found that the spectrum obtained by directly applying the Raman spectrometer to test the surface coating of finished silicon steel is not good. In order to solve the problems of low resolution and little effective spectrum information in the existing characterization methods of silicon steel surface coatings, the present invention discloses a method for analyzing and characterizing silicon steel coatings using a laser confocal Raman spectrometer. This method requires re-sampling of the coating sample and formulating the corresponding analysis conditions of the Raman spectrometer to obtain a high-resolution, clear and definite spectrum. Summary of the Invention

[0004] This invention aims to establish an efficient, accurate, and highly operational analytical characterization method for silicon steel coatings using confocal laser Raman spectroscopy. This method rapidly generates Raman spectra of the coatings, which can be analyzed to determine the coating structure and obtain information about its composition. This method has significant practical implications for studying silicon steel coating structure, optimizing coating composition, and developing new coating varieties.

[0005] In order to solve the problems of low resolution and little effective spectrum information in existing silicon steel surface coating characterization methods, the present invention discloses a method for analyzing and characterizing silicon steel coatings using a laser confocal Raman spectrometer, which comprises at least the following steps:

[0006] Step 1: Use a wire rod applicator to evenly apply the coating liquid sample to a high-temperature resistant glass sheet to obtain a well-coated sample sheet;

[0007] Step 2: placing the sample coated slice obtained in step 1 in an oven for drying to obtain a slice with a dried coating film;

[0008] Step 3: Place the thin slice with the dried coating film obtained in step 2 on the sample stage of the laser confocal Raman spectrometer, focus, project, and collect to obtain the Raman spectrum of the coating sample to be tested.

[0009] The wire diameter of the wire rod coater is determined according to the target thickness and the solid content of the coating. The thinner the target thickness of the coating and the lower the solid content, the smaller the required wire diameter.

[0010] Optionally, the coating liquid sample to be tested refers to silicon steel liquid coating.

[0011] Optionally, the wire diameter of the wire rod coater in step 1 is 2 to 5 μm;

[0012] Optionally, the glass sheet in step 1 has a high temperature resistance of ≥ 200°C.

[0013] Optionally, the glass slice in step 1 is a frosted glass slide.

[0014] Optionally, the drying conditions in step 2 are as follows:

[0015] The drying temperature is 100-160°C;

[0016] The drying time is 1 to 2 hours.

[0017] Optionally, if the film with the dried coating in step 2 cannot be tested in time, it needs to be placed in a desiccator to prevent water absorption from affecting subsequent testing.

[0018] Optionally, the focusing objective lens in step 3 is 10 to 50 times. Due to the surface roughness limit of the sample (Ra is 1 to 50 μm), a higher objective lens is not recommended.

[0019] Optionally, the laser wavelength used for projection in step three is 404-786 nm.

[0020] Optionally, the intensity of the laser used for projection in step 3 is 50% to 100%.

[0021] Optionally, the acquisition time in step 3 is 1 to 10 seconds.

[0022] Optionally, the Raman shift number used in step 3 is 100 to 5000 cm -1 .

[0023] Optionally, the signal-to-background ratio (SBR) of the Raman spectrum of the coating sample to be tested in step 3 is ≥ 10:1.

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

[0025] 1) When the surface coating of the finished silicon steel sheet is tested, the characteristic peaks of the Raman spectrum obtained are not obvious, and the peak position and peak intensity of the coating cannot be clearly distinguished. The Raman spectrum of the glass slide coating film sample obtained by the method of the present invention has clear characteristic peaks, which can more clearly distinguish the peak position and peak intensity of the components in the coating.

[0026] 2) This invention uses confocal laser Raman spectroscopy to establish an efficient, accurate, and highly operable analytical characterization method for silicon steel coatings. This method can rapidly generate Raman spectra of the coatings, which can be analyzed to determine the coating structure and obtain information related to the coating composition. This method has important practical significance for studying the structure of silicon steel coatings, optimizing coating composition, and developing new coating varieties. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a diagram of a 5μm wire rod coater used in Example 1 of the present invention;

[0028] Figure 2 This is a picture of a glass slide with a dried coating film in Example 1 of the present invention;

[0029] Figure 3 1 is a comparison diagram of the Raman spectra of the silicon steel coating samples to be tested in Example 1 of the present invention and Comparative Example 1;

[0030] Figure 4 This is a picture of a glass slide with a dried coating film in Example 2 of the present invention;

[0031] Figure 5 This is a comparison diagram of the Raman spectra of the silicon steel coating samples to be tested in Example 2 of the present invention and Comparative Example 2. DETAILED DESCRIPTION

[0032] The present invention will be further described below with reference to specific examples, but the present invention is not limited thereto in any way.

[0033] Unless otherwise specified, the reagents and samples used in the present invention were purchased.

[0034] In Examples 1 and 2 of the present invention and Comparative Examples 1 and 2, the samples were analyzed using a LabRAM Odyssey laser confocal Raman spectrometer.

[0035] Example 1

[0036] A method for analyzing and characterizing a silicon steel coating using a laser confocal Raman spectrometer comprises the following steps:

[0037] Step 1: Use a wire rod applicator (wire diameter 5 μm, see Figure 1 ) Evenly apply 0.5 ml of the coating liquid sample to be tested (solid content 60%) onto a frosted glass slide (high temperature resistant ≥ 200°C) to obtain a sample-coated glass slide;

[0038] Step 2: Place the coated glass slide in an oven at 105°C and dry for 1 hour to obtain a glass slide with a dried coating film. After drying, the sample is as follows: Figure 2 As shown;

[0039] Step 3: Place the glass slide with the dried coating film on the sample stage of the laser confocal Raman spectrometer, select the 10x objective lens and focus on the surface of the sample to be measured according to the instrument requirements;

[0040] Step 4: Select a laser with a wavelength of 532 nm and an intensity of 100% to project onto the surface of the glass slide with the dried coating film in step 3. The acquisition time is 1 s and the Raman shift range is 110 to 4900 cm -1 , and then collect the signal to obtain the Raman spectrum of the coating sample to be tested. The spectrum results are as follows Figure 3 As shown in the figure (i.e. the spectrum obtained by the technology of Example 1), the results show that the detection spectrum obtained in this example contains 441cm -1 、610cm -1 There are more than ten effective peaks with a signal-to-background ratio greater than 10:1, and the composition of the sample can be judged by the position of the peaks.

[0041] Comparative Example 1

[0042] The difference from Example 1 is that the coating liquid sample to be tested (solid content 60%) is directly applied to the surface of the silicon steel product for testing. The comparison results are as follows: Figure 3 As shown (the spectrum obtained without using the technology of Example 1), it shows that no effective peaks are distinguished in the spectrum directly detected by the silicon steel finished product, and the overall spectrum is affected by the silicon steel matrix, and no distinguishable spectrum information can be obtained.

[0043] Example 2

[0044] A method for analyzing and characterizing a silicon steel coating using a laser confocal Raman spectrometer comprises the following steps:

[0045] Step 1: Use a wire rod applicator (wire diameter of 2 μm) to evenly apply 0.4 ml of the coating liquid sample to be tested (solid content 20%) onto a frosted glass slide (high temperature resistant ≥ 200°C) to obtain a sample-coated glass slide;

[0046] Step 2: Place the coated glass slide in an oven at 150°C for 2 hours to dry it. The glass slide with the dried coating film is then dried. Figure 4 As shown;

[0047] Step 3: Place the glass slide with the dried coating film on the sample stage of the laser confocal Raman spectrometer, select the 50x objective lens and focus on the surface of the sample to be measured according to the instrument requirements;

[0048] Step 4: Select a laser with a wavelength of 785 nm and an intensity of 50% to project onto the surface of the glass slide with the dried coating film in step 3. The acquisition time is 5 s and the Raman shift range is 104 to 3490 cm -1 , and then collect the signal to obtain the Raman spectrum of the silicon steel coating sample to be tested. Figure 5 The results of the spectrum of silicon steel product testing and the detection using this technology are compared. Figure 5 As shown in the figure (spectrum obtained by the technology of Example 2), it can be seen from the figure that the detection spectrum obtained in this embodiment contains 1092cm -1 、2944cm -1 There are more than ten effective peaks with a signal-to-background ratio greater than 10:1, and the composition of the sample can be judged by the position of the peaks.

[0049] Comparative Example 2

[0050] The difference from Example 2 is that the coating liquid sample to be tested (solid content 20%) is directly applied to the surface of the silicon steel product for testing. The spectrum results are as follows: Figure 5 As shown (i.e., the spectrum obtained without the technology used in Example 2), the results show that when the coating liquid sample is directly applied to silicon steel, no effective peaks can be distinguished, and the overall spectrum is affected by the silicon steel matrix, and no distinguishable spectrum information can be obtained.

[0051] The above descriptions are merely several embodiments of the present invention and do not constitute any form of limitation to the present invention. Although the present invention is disclosed as above in terms of preferred embodiments, they are not intended to limit the present invention. Any technician familiar with the present profession who, without departing from the scope of the technical solution of the present invention, makes slight changes or modifications using the technical contents disclosed above are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. A method for analyzing and characterizing silicon steel coatings using laser confocal Raman spectroscopy, characterized in that: The method comprises at least the following steps: Step 1: Use a wire rod applicator to evenly apply the coating liquid sample to a high-temperature resistant glass sheet to obtain a well-coated sample sheet; Step 2: placing the sample coated slice obtained in step 1 in an oven for drying to obtain a slice with a dried coating film; Step 3: Place the thin slice with the dried coating film obtained in step 2 on the sample stage of the laser confocal Raman spectrometer, focus, project, and collect to obtain the Raman spectrum of the coating sample to be tested.

2. The method according to claim 1, characterized in that The wire diameter of the wire rod coater in step 1 is 2 to 5 μm.

3. The method according to claim 1, characterized in that The high temperature resistance of the glass sheet in step 1 is ≥ 200°C.

4. The method according to claim 1, wherein The glass slice in step 1 is a frosted glass slide.

5. The method according to claim 1, wherein The drying conditions in step 2 are as follows: The drying temperature is 100-160°C; The drying time is 1 to 2 hours.

6. The method according to claim 1, characterized in that The focusing objective lens in step 3 is 10 to 50 times.

7. The method according to claim 1, characterized in that The laser wavelength used in the projection in step 3 is 404-786nm; The intensity of the laser used in the projection in step 3 is 50% to 100%.

8. The method according to claim 1, characterized in that The acquisition time in step 3 is 1 to 10 seconds; The Raman shift number used in step 3 is 100-5000 cm -1 .

9. The method according to claim 1, characterized in that The signal-to-background ratio (SBR) of the Raman spectrum of the coating sample to be tested obtained in step 3 is ≥ 10:1.

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