A method for evaluating the phosphating quality of galvanized chemically post-treated steel sheets

Abstract

The present invention particularly relates to a method for evaluating the phosphating quality of a galvanized chemical post-treatment steel plate, and belongs to the technical field of surface treatment. The method comprises: obtaining a phosphating sample; detecting the content of characteristic elements on the surface of the phosphating sample to obtain the content value of the characteristic elements; judging the phosphating quality of the phosphating sample according to the content value of the characteristic elements; wherein the characteristic elements are elements that are unfavorable to phosphating; and evaluating the phosphating quality of the galvanized chemical post-treatment steel plate by detecting the content value of the characteristic elements remaining between the phosphating film layer and the galvanized layer in the galvanized chemical post-treatment steel plate after phosphating treatment and utilizing the residual amount of the characteristic elements that are unfavorable to phosphating.

Description

Technical Field

[0001] The invention belongs to the technical field of surface treatment, and particularly relates to a method for evaluating the phosphating quality of a galvanized chemical post-treatment steel plate. Background Art

[0002] Currently, there are many standards for evaluating the phosphating quality of cold-rolled steel sheets, such as observing the surface color of phosphated steel sheets with the naked eye, observing the size of phosphating crystals with a scanning electron microscope, and measuring the quality of phosphating film by weighing method. However, there is no unified standard for evaluating the phosphating quality of galvanized chemically post-treated steel sheets. The national standard for evaluating the phosphating quality of cold-rolled steel sheets lacks accuracy in evaluating the phosphating quality of galvanized chemically post-treated steel sheets. This is mainly because the surface elements and properties of cold-rolled steel sheets and galvanized chemically post-treated steel sheets are quite different. After chemical post-treatment, the galvanized steel sheet will have a layer of organic or inorganic or organic / inorganic composite film on its surface, and some characteristic elements contained in this chemical film will have a great influence on the phosphating quality. Because the galvanized chemical post-treatment steel sheet needs to undergo a degreasing process before phosphating to remove the elements that affect phosphating, but the degreasing capabilities of various automobile OEMs are different, and the removal effects of different characteristic elements contained in the chemical film layer in the same degreasing solution are different. When the content of some characteristic elements is high, phosphating will not occur, resulting in the inability to accurately evaluate the phosphating quality of the galvanized chemical post-treatment steel sheet. Summary of the invention

[0003] The purpose of the present application is to provide a method for evaluating the phosphating quality of galvanized chemically post-treated steel sheets, so as to solve the problem that the phosphating quality of galvanized chemically post-treated steel sheets cannot be accurately evaluated at present.

[0004] The embodiment of the present invention provides a method for evaluating the phosphating quality of a galvanized chemical post-treatment steel sheet, the method comprising:

[0005] Obtaining a phosphating sample;

[0006] Detecting the content of characteristic elements on the surface of the phosphating sample to obtain the content value of the characteristic elements;

[0007] According to the content value of the characteristic element, judging the phosphating quality of the phosphating sample;

[0008] Wherein, the characteristic element is an element that is unfavorable for phosphating.

[0009] Optionally, the detecting of the content of characteristic elements on the surface of the phosphating sample to obtain the content value of the characteristic elements specifically includes:

[0010] Performing a glow spectrum scan on the surface of the phosphating sample along the radial depth direction to obtain a curve of the characteristic element changing with thickness;

[0011] The characteristic element content value is obtained by integrating the curve of the characteristic element changing with the thickness until an integration end point is set.

[0012] Optionally, the integration endpoint is set to a radial thickness corresponding to a 70-90% decrease in the peak value of the phosphorus content.

[0013] Optionally, the characteristic element includes at least one of silicon, zirconium, molybdenum and chromium.

[0014] Optionally, obtaining the phosphating sample specifically includes:

[0015] The galvanized chemical post-treatment steel sheet is subjected to phosphating treatment to obtain a phosphating sample.

[0016] Optionally, the phosphating treatment includes degreasing and phosphating.

[0017] Optionally, the degreasing liquid is an alkaline degreasing liquid, the temperature of the alkaline degreasing liquid is 45-55°C, the degreasing time is 3-7 minutes, the temperature of the phosphating liquid is 35-40°C, and the phosphating time is 1-3 minutes.

[0018] Optionally, the pH value of the alkaline degreasing solution is 12-13, and the pH value of the phosphating solution is 1-2.

[0019] Optionally, the galvanized chemically post-treated steel sheet includes one of a zinc-coated steel sheet and a zinc-aluminum-magnesium-coated steel sheet.

[0020] Optionally, the size of the galvanized chemically post-treated steel plate is one of 100mm*200mm and 70mm*150mm.

[0021] One or more technical solutions in the embodiments of the present invention have at least the following technical effects or advantages:

[0022] The method for evaluating the phosphating quality of a galvanized chemically post-treated steel sheet provided in an embodiment of the present invention detects the residual characteristic element content between the phosphating film layer and the galvanized layer in the galvanized chemically post-treated steel sheet after phosphating treatment, and utilizes the residual characteristic element that is unfavorable for phosphating to evaluate the phosphating quality of the galvanized chemically post-treated steel sheet.

[0023] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention, it can be implemented according to the contents of the specification. In order to make the above and other purposes, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0025] Figure 1 It is a schematic diagram of the structure of a galvanized chemical post-treatment steel plate after phosphating provided by an embodiment of the present invention;

[0026] Figure 2 is a curve diagram showing the change of the P element content versus the test thickness provided in Example 1 of the present invention;

[0027] Figure 3 is a curve diagram showing the change of Si element content versus test thickness provided in Example 1 of the present invention;

[0028] Figure 4 is a curve diagram showing the change of P element content versus test thickness provided in Example 2 of the present invention;

[0029] Figure 5 is a curve diagram showing the change of Si element content versus test thickness provided in Example 2 of the present invention;

[0030] Figure 6 is a surface morphology image of a galvanized steel sheet after phosphating provided in Example 1 of the present invention;

[0031] Figure 7 is a surface morphology image of a galvanized steel sheet after phosphating provided in Example 2 of the present invention;

[0032] Figure 8 It is a flow chart of the method provided by the embodiment of the present invention. DETAILED DESCRIPTION

[0033] The present invention will be described in detail below in conjunction with specific implementations and examples, and the advantages and various effects of the present invention will be more clearly presented. It should be understood by those skilled in the art that these specific implementations and examples are used to illustrate the present invention, rather than to limit the present invention.

[0034] Throughout the specification, unless otherwise specifically stated, the terms used herein should be understood as meanings commonly used in the art. Therefore, unless otherwise defined, all technical and scientific terms used herein have the same meanings as those generally understood by those skilled in the art to which the present invention belongs. In the event of a conflict, the present specification takes precedence.

[0035] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in the present invention can be purchased from the market or prepared by existing methods.

[0036] The technical solution of the embodiment of the present application is to solve the above technical problems, and the overall idea is as follows:

[0037] According to a typical embodiment of the present invention, a method for evaluating the phosphating quality of a galvanized chemical post-treatment steel sheet is provided, the method comprising:

[0038] S1. Obtaining a phosphating sample;

[0039] In some embodiments, obtaining the phosphating sample specifically comprises:

[0040] The galvanized chemical post-treatment steel sheet is subjected to phosphating treatment to obtain a phosphating sample.

[0041] Specifically, the phosphating treatment includes degreasing and phosphating. The degreasing liquid for degreasing is an alkaline degreasing liquid, the temperature of the alkaline degreasing liquid is 45-55°C, the degreasing time is 3-7 minutes, the temperature of the phosphating liquid is 35-40°C, and the phosphating time is 1-3 minutes. The pH value of the alkaline degreasing liquid is 12-13, and the pH value of the phosphating liquid is 1-2.

[0042] In some embodiments, the galvanized chemical post-treatment steel sheet includes one of a zinc-coated steel sheet and a zinc-aluminum-magnesium-coated steel sheet.

[0043] In some embodiments, the size of the galvanized chemical post-treatment steel plate is one of 100 mm*200 mm and 70 mm*150 mm.

[0044] In this embodiment, specifically, a galvanized chemical post-treatment steel plate of a certain size is taken, and a fixed degreasing process, a phosphating process, etc. are performed for phosphating treatment to obtain a phosphated sample. The degreasing and phosphating methods are as follows: immersing the galvanized chemical post-treatment steel plate of a certain size in an alkaline degreasing solution of 50±5°C for 5 minutes, then washing and spraying 2-3 times with water, and then immersing it in a surface conditioning solution at room temperature for 1 minute, and then immersing it in a phosphating solution of 35-40°C for 2 minutes, and then washing and spraying 1-2 times with water, and finally drying it with cold air to obtain a phosphating sample.

[0045] S2. Detect the content of characteristic elements on the surface of the phosphating sample, wherein the characteristic elements are elements that are unfavorable to phosphating, and obtain the content value of the characteristic elements;

[0046] Specifically, the characteristic element includes at least one of silicon, zirconium, molybdenum and chromium.

[0047] The characteristic elements contained in the surface of different galvanized chemical post-treatment steel sheets may be different, and the characteristic elements are determined according to the actual situation. After phosphating, characteristic elements that are unfavorable to phosphating may still exist, which will affect the quality of phosphating. As shown in the attached figure, layer 1 is the iron matrix, layer 2 is the zinc coating, layer 3 is the phosphating film, and layer 4 sandwiched between layers 2 and 3 is the residual elements that are unfavorable to phosphating or oxides and complexes containing the elements.

[0048] In some embodiments, the detecting of the content of characteristic elements on the surface of the phosphating sample to obtain the content value of the characteristic elements specifically includes:

[0049] S2.1. Glow spectrum scanning is performed on the surface of the phosphating sample along the radial depth direction to obtain a curve of the characteristic element varying with thickness;

[0050] S2.2. Integrate the curve of the characteristic element changing with thickness until an integration end point is set to obtain the content value of the characteristic element.

[0051] Specifically, the integration endpoint is set to be the radial thickness corresponding to a 70-90% decrease in the peak value of the phosphorus content.

[0052] The endpoint of characteristic element integration is determined by the radial thickness corresponding to the decrease of 70-90% of the peak value of phosphorus content. It is mainly to take into account the unfavorable phosphating element content remaining between the phosphating film layer and the galvanized layer as much as possible. When the endpoint of integration is within 70% of the decrease of the peak value of phosphorus content, part of the elements remain on the surface closer to the galvanized layer and leak, resulting in a smaller result. When the endpoint of integration is more than 90% of the decrease of the peak value of phosphorus content, the characteristic element content in the integration includes part of the element content in the coating or even the iron matrix, resulting in a large deviation of the result, which is not conducive to the accurate evaluation of the phosphating quality. Therefore, the radial thickness corresponding to the decrease of 70-90% of the peak value of phosphorus content is taken as the endpoint of integration. For example, the peak value of phosphorus content is a%, and the content after the phosphorus content is reduced by 80% is a%X(1-80%)=2a‰. In the curve, the radial thickness corresponding to the phosphorus content of 2a‰ is bμm, then the endpoint of integration of the characteristic element in the sample is bμm, and then the characteristic element is integrated from 0-bμm. The smaller the value, the better the phosphating quality.

[0053] In this embodiment, specifically, glow spectrometry (GDS) is used to progressively scan the phosphating sample obtained in the first step from the radial depth of the phosphating film surface to obtain a curve of the change in the content of phosphorus and characteristic elements with thickness; the radial thickness corresponding to a 70-90% decrease in the peak value of the phosphorus content is determined, and this is used as the integration end point of the characteristic element, and the characteristic element is integrated from the radial thickness of 0 μm to the integration end point determined in the second step to obtain the content value of the characteristic element.

[0054] S3. According to the content value of the characteristic element, judging the phosphating quality of the phosphating sample;

[0055] Specifically, the smaller the integral value is and the smaller the content of the characteristic element is, the better the phosphating quality is.

[0056] The evaluation method of the phosphating quality of the galvanized chemical post-treatment steel sheet of the present application will be described in detail below in combination with the embodiments, control examples and experimental data.

[0057] Example 1

[0058] A method for evaluating the phosphating quality of a galvanized chemical post-treatment steel sheet, the method comprising:

[0059] Take a sample of galvanized chemically treated steel plate A, with a size of 100mmX200mm. Treat its surface according to the following steps:

[0060] Immerse sample A in alkaline degreasing solution at 50±5℃ for 5 minutes, then wash and spray with water 2-3 times, then immerse it in surface conditioning solution at room temperature for 1 minute, then immerse it in phosphating solution at 35-40℃ for 2 minutes, then wash and spray with water 1-2 times, and finally blow dry with cold air to obtain phosphating sample A.

[0061] Then, the surface elements of the phosphating sample A were analyzed by glow spectroscopy, and the test thickness was 0-10μm. The curve of the change of the element content of phosphorus and silicon with radial thickness is shown in the figure Figure 2 and Figure 3 shown.

[0062] The integral of characteristic silicon content with radial thickness:

[0063] Figure 2 The peak value of phosphorus in the sample is 6.182%. The peak value is reduced by 80% to obtain the content data of 6.182X (1-80%) = 1.24%. Figure 2 It can be seen that when the phosphorus content is 1.24%, the corresponding radial thickness is 1.52μm, and the integral end point of the characteristic element is 1.52μm, that is, for silicon content Figure 3 Integrate from 0-1.52μm to obtain the integral value.

[0064] The surface of phosphating sample A was subjected to microscopic morphology analysis (SEM), and the results are as follows: Figure 6 shown.

[0065] Example 2

[0066] A method for evaluating the phosphating quality of a galvanized chemical post-treatment steel sheet, the method comprising:

[0067] Take the sample B of the galvanized chemical post-treatment steel plate with the specification of 100mmX200mm. Treat its surface according to the following steps:

[0068] Immerse sample B in alkaline degreasing solution at 50±5℃ for 5 minutes, then wash and spray with water 2-3 times, then immerse it in surface conditioning solution at room temperature for 1 minute, then immerse it in phosphating solution at 35-40℃ for 2 minutes, then wash and spray with water 1-2 times, and finally dry it with cold air to obtain phosphating sample B.

[0069] Then, the surface elements of the phosphating sample B were analyzed by glow spectroscopy, and the test thickness was 0-10μm. The curve of the change of the element content of phosphorus and silicon with radial thickness is shown in the figure Figure 4 and Figure 5 shown.

[0070] The integral of characteristic silicon content with radial thickness:

[0071] Figure 4 The peak value of phosphorus in the sample is 6.854%. The peak value is reduced by 80% to obtain the content data of 6.854X (1-80%) = 1.37%. Figure 4 It can be seen that when the phosphorus content is 1.37%, the corresponding radial thickness is 1.11μm, and the integral end point of the characteristic element is 1.11μm, that is, for silicon content Figure 5 Integrate from 0-1.11 μm to obtain the integral value.

[0072] The surface of phosphating sample B was analyzed by scanning electron microscope (SEM). Figure 7 shown.

[0073] Through calculation, the integral of silicon content in Example 1 is significantly less than that in Example 2, that is, the content of characteristic elements that are unfavorable to phosphating is lower, so its phosphating quality is better. The two samples were characterized by microscopic morphology (SEM), such as Figure 6 and Figure 7 As shown, the phosphating film of Example 1 is dense, completely covers the substrate, and the phosphating crystal grain size is uniform, indicating high phosphating quality, which is consistent with the evaluation results of this method.

[0074] One or more technical solutions in the embodiments of the present invention have at least the following technical effects or advantages:

[0075] The method provided in the embodiment of the present invention evaluates the phosphating quality by measuring the residual amount of characteristic elements that have an adverse effect on phosphating between the phosphating film layer and the galvanized layer. The method is simple and easy to implement with high accuracy, and at the same time improves the standard for evaluating the phosphating quality of galvanized chemical post-treatment steel plates.

[0076] Finally, it should be noted that the terms "comprises," "includes," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that includes a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements that are inherent to such process, method, article, or apparatus.

[0077] Although the preferred embodiments of the present invention have been described, those skilled in the art may make additional changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

[0078] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A method for evaluating the phosphating quality of a galvanized chemically post-treated steel sheet, characterized in that: The method comprises: Obtaining a phosphating sample; Detecting the content of characteristic elements on the surface of the phosphating sample to obtain the content value of the characteristic elements; According to the content value of the characteristic element, judging the phosphating quality of the phosphating sample; Wherein, the characteristic element includes at least one of silicon, zirconium, molybdenum and chromium; The step of detecting the content of characteristic elements on the surface of the phosphating sample to obtain the content value of the characteristic elements specifically includes: The phosphating samples were progressively scanned from the radial depth of the phosphating film surface using glow spectroscopy to obtain a curve of the change in phosphorus and characteristic element content with thickness; the radial thickness corresponding to a 70-90% decrease in the peak value of the phosphorus content was determined, and this was used as the integration end point of the characteristic element. The characteristic element was integrated from the radial thickness of 0 μm to the determined integration end point to obtain the content value of the characteristic element.

2. The method for evaluating the phosphating quality of a galvanized chemically post-treated steel sheet according to claim 1, characterized in that: The phosphating sample is obtained, specifically comprising: The galvanized chemical post-treatment steel sheet is subjected to phosphating treatment to obtain a phosphating sample.

3. The method for evaluating the phosphating quality of a galvanized chemical post-treatment steel sheet according to claim 2, characterized in that: The phosphating treatment includes degreasing and phosphating.

4. The method for evaluating the phosphating quality of a galvanized chemical post-treatment steel sheet according to claim 3, characterized in that: The degreasing liquid is an alkaline degreasing liquid, the temperature of the alkaline degreasing liquid is 45-55°C, the degreasing time is 3-7 minutes, the temperature of the phosphating liquid is 35-40°C, and the phosphating time is 1-3 minutes.

5. The method for evaluating the phosphating quality of a galvanized chemical post-treatment steel sheet according to claim 4, characterized in that: The pH value of the alkaline degreasing solution is 12-13, and the pH value of the phosphating solution is 1-2.

6. The method for evaluating the phosphating quality of a galvanized chemical post-treatment steel sheet according to claim 2, characterized in that: The galvanized chemical post-treatment steel sheet comprises one of a zinc-coated steel sheet and a zinc-aluminum-magnesium-coated steel sheet.

7. The method for evaluating the phosphating quality of a galvanized chemically post-treated steel sheet according to claim 2, characterized in that: The size of the galvanized chemical post-treatment steel plate is one of 100mm*200mm and 70mm*150mm.

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