Preparation method of quality test standard sample for zinc coating in galvanized steel

Abstract

The invention relates to a preparation method of a galvanized layer quality test standard sample in galvanized steel, and belongs to the technical field of galvanized layer detection. The specific method comprises the following steps: selecting a to-be-detected sample block, and cutting into five pieces of samples; wherein the first sample takes the central area of a to-be-detected sample block and is circular; 2-5 samples are adjacent and are in a sector ring shape, and the area is marked as Si; weighing the mass of No. 2 to No. 5 samples, and recording the mass as mi; carrying out corrosion treatment on the No. 2-5 samples, weighing the mass of the No. 2-5 samples after corrosion, and recording the mass of the No. 2-5 samples as m'i; calculating the zinc layer mass per unit area of the No.2-No.5 samples as rho i = (mi-m'i) / Si; and if the ratio of the range value to the average value of the measurement results of the No.2-No.5 samples does not exceed 2%, taking the average value of the No.2-No.5 samples as the coating weight of the No.1 sample, and taking the No.1 sample as a standard sample. Through the preparation method of the test standard sample, the deviation between the test value and the actual value of the prepared sample is reduced.

Description

Technical Field

[0001] This invention relates to the technical field of zinc coating detection, and specifically to a method for preparing a standard sample for testing the quality of zinc coating in galvanized steel. Background Technology

[0002] Galvanized steel refers to a surface treatment technique in which a layer of zinc is plated onto the surface of steel for aesthetic purposes and rust prevention. The primary method used is hot-dip galvanizing. The zinc coating is mainly used to prevent corrosion of steel, and its protective performance is greatly influenced by the coating thickness. After passivation treatment, dyeing, or application of a protective agent, the protective and decorative properties of the zinc coating can be significantly improved.

[0003] Standard samples for testing the quality of the galvanized coating on galvanized steel are the core benchmark for ensuring testing accuracy, process compliance, and cost-effectiveness, providing a reliable basis for quality control and industry standardization. Appendix A of GB / T 1839-2008 "Test Methods for the Quality of Galvanized Coatings of Steel Products" provides a recommended method for preparing standard samples for testing the quality of the galvanized coating on steel products. Specifically, five samples are prepared in a cross shape on a sample block with a uniform coating, where sample 1 is located at the center of the block, and samples 2-5 are evenly distributed along the four directions of sample 1. The coating mass (g / m³) of samples 2-5 is determined by gravimetric method. 2 If the reproducibility (ratio of the range to the average of the four samples) of the test results for samples 2-5 does not exceed 3%, then the average of the four samples is taken as the coating weight of sample 1, and sample 1 is used as the standard sample. The drawback of the standard sample preparation method recommended in GB / T 1839-2008 "Test Method for the Quality of Zinc Coating of Steel Products" is that it only provides a general preparation method and does not specify requirements for sample shape, sealing of untested surfaces, etc. In practical application, this can cause the average zinc coating weight of samples 2-5 to deviate from the actual zinc coating weight of sample 1. Summary of the Invention

[0004] To address the problem that existing methods for testing the quality of galvanized coatings in steel products result in significant discrepancies between the tested and actual quality of the prepared samples, this invention provides a method for preparing standard samples for testing the quality of galvanized coatings in galvanized steel, thereby resolving the aforementioned issue.

[0005] The technical solution of this invention is as follows: A method for preparing a standard sample for testing the quality of the zinc coating in galvanized steel involves selecting a sample block to be tested and cutting it into 5 pieces; sample 1 is taken from the central area of ​​the sample block to be tested and is circular; samples 2 to 5 are adjacent and are all fan-shaped rings, with the area denoted as S. i Samples 4 and 5 are placed next to sample 1; the mass of samples 2 through 5 is measured and recorded as m. iThen, samples 2 through 5 were subjected to etching treatment, and the mass of samples 2 through 5 after etching was recorded as m'. i Calculate the mass of zinc layer per unit area for samples 2-5 as ρ. i = (m i - m' i )÷S i If the ratio of the range to the average value of the measurement results of samples 2 to 5 does not exceed 2%, then the average value of samples 2 to 5 shall be taken as the coating weight of sample 1, and sample 1 shall be used as the standard sample.

[0006] Furthermore, the selected test samples should have a uniform coating and be free of scratches; samples with obvious local damage should not be used. Care should be taken to avoid surface damage when cutting the samples.

[0007] Furthermore, after obtaining the sample, the sample surface needs to be cleaned with anhydrous ethanol and then thoroughly dried.

[0008] Furthermore, ensure that the weighing accuracy is better than 1% of the expected mass of the sample coating; when the sample coating mass is not less than 0.1 g, the weighing accuracy should be to 0.001 g. By obtaining the expected mass of sample 1, the weighing accuracy of the sample can be determined. The weighing accuracy of the sample can then be used to accurately select a balance for weighing.

[0009] Furthermore, the mass of the zinc layer per unit area of ​​the cleaned sample No. 1 was measured using the fluorescence X-ray method, denoted as ρ'1. The expected mass m of the coating on one side of the sample was calculated using the formula m = S1 × ρ'1. Section 6.2 of GB / T 1839-2008 "Test Method for the Quality of Zinc Coating of Steel Products" clearly states: "When weighing the sample using a balance, the weighing accuracy should be better than 1% of the expected mass of the sample coating. When the sample coating mass is not less than 0.1 g, the weighing should be accurate to 0.001 g," to ensure the accuracy of the weighing data. This invention utilizes the fluorescence X-ray method to obtain the expected mass, enabling a more accurate acquisition of the expected mass and ensuring the actual weighed mass m. i Accurate. This is something that GB / T 1839-2008 does not explicitly specify.

[0010] Furthermore, before etching the sample, apply a thick layer of an acid-insoluble, adhesive protective agent, such as petrolatum, to the non-test surface to ensure complete coverage and prevent contamination of the test surface. Note that the protective agent should not easily detach during sample preparation and should maintain full coverage of the non-test surface.

[0011] Furthermore, the etching solution used for the etching treatment was 3.5 g of hexamethylenetetramine (C6H4H4O7). 12 The solution is prepared by dissolving N4 in 500 ml of concentrated hydrochloric acid (ρ=1.19 g / ml) and diluting it with distilled or deionized water to 1000 ml.

[0012] Furthermore, the amount of etching solution used per square centimeter of sample surface area should be ≥10 ml.

[0013] Further, after the corrosion treatment, the samples are removed, and all protective agents adhering to the unmeasured surfaces and loose deposits adsorbed on the corroded surfaces are completely removed. Finally, the samples are cleaned with ethanol and dried quickly, or the moisture can be absorbed with absorbent paper and then quickly dried with hot air. Then, the masses of samples 2 to 5 are weighed.

[0014] The beneficial effects of this invention are as follows: This invention provides an accurate, convenient, and economical method for preparing standard samples for testing the quality of galvanized coatings on steel products. The method involves cutting samples 2-5 into a fan-shaped ring, with samples 4 and 5 placed adjacent to sample 1. The expected quality of the coating is then measured using fluorescence X-ray diffraction, and the weighing accuracy is determined through a calculation formula, allowing for the selection of a suitable precision method. Balance Furthermore, the sealing method for the non-tested surfaces was clarified, thereby improving the accuracy of standard sample preparation. The test standard sample preparation method of this invention reduces the deviation between the tested and actual values ​​of the prepared samples. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 This is a standard sample sampling diagram from GB / T 1839-2008 "Test Methods for the Quality of Zinc Coatings in Steel Products".

[0017] Figure 2 This is a standard sample sampling diagram of the present invention.

[0018] In the figure, 1 is sample 1, 2 is sample 2, 3 is sample 3, 4 is sample 4, and 5 is sample 5. Detailed Implementation

[0019] To enable those skilled in the art to better understand the technical solutions of this invention, the technical solutions of the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this invention.

[0020] Example 1 (1) Using the fluorescence X-ray method, select a sample block with a uniform coating and no scratches on the surface, measuring 300 mm × 300 mm, and proceed according to... Figure 2 Five samples were obtained using the cutting method shown. Care should be taken to avoid surface damage when cutting the samples. Samples with obvious localized damage should not be used. Sample 1 is circular with an area of ​​S1. Samples 2, 3, 4, and 5 are annular segments with areas of S1 = 0.00283 m². 2 S2 = 0.00283 m 2 S3 = 0.00291 m 2 S4 = 0.00276 m 2 And S5 = 0.00285 m 2 Samples 4 and 5 are located next to sample 1.

[0021] (2) Clean the sample surface with anhydrous ethanol and dry it thoroughly.

[0022] (3) The mass ρ of the zinc layer per unit area of ​​sample No. 1 was measured by fluorescence X-ray method. i It is 20.636 g / m 2 Using the formula m = S i ×ρ' i The expected mass of the coating on the sample is calculated to be 0.0584 g. The weighing accuracy should be better than 0.000584 g. A balance with an accuracy of 0.0001 g should be used for subsequent weighing.

[0023] (4) The masses of samples No. 2, No. 3, No. 4 and No. 5 were weighed using a balance and found to be 0.6391 g, 0.6461 g, 0.6399 g and 0.6492 g respectively.

[0024] (5) Apply a thick layer of an acid-insoluble, adhesive protective agent, such as petrolatum, to the non-test surface to ensure complete coverage and prevent contamination of the test surface. Note that the protective agent should not easily fall off during sample preparation and should cover the non-test surface throughout the process.

[0025] (6) Under room temperature conditions, completely immerse the sample coated with the protective agent in the etching solution until the coating is completely dissolved. The dissolution process is considered complete when the hydrogen evolution (violent bubbling) clearly stops. The etching solution is 3.5 g of chemically pure hexamethylenetetramine (C6H4H2O). 12 The test solution is prepared by dissolving N4 in 500 ml of concentrated hydrochloric acid (p = 1.19 g / ml) and diluting it with distilled or deionized water to 1000 ml. The volume of the test solution is usually no less than 10 ml per square centimeter of sample surface area.

[0026] (7) Remove the sample and completely remove the protective agent adhering to the unmeasured surface and the loose adhering substances adsorbed on the corroded surface. Finally, wash with ethanol, dry quickly, or use absorbent paper to remove moisture and blow dry quickly with hot air. Weigh again and the masses are 0.5810 g, 0.5857 g, 0.5829 g and 0.5906 g respectively.

[0027] (8) The mass of zinc layer per unit area of ​​the tested surface is calculated to be 20.5300 g / m². 2 20.7560 g / m 2 20.6522g / m 2 and 20.5614 g / m 2 .

[0028] (9) Calculate the reproducibility of the test results for samples 2, 3, 4, and 5: (20.7560 - 20.5300) / [(20.5300 + 20.7560 + 20.6522 + 20.5614) / 4] × 100% = 1.1%, which is less than 2%. Sample 1 can be used as a standard sample, with a zinc layer mass of 20.6250 g / m² per unit area. 2 .

[0029] Example 2 (1) Using the fluorescence X-ray method, select a sample block with a uniform coating and no scratches on the surface, measuring 300 mm × 300 mm, and proceed according to... Figure 2 Five samples were obtained using the cutting method shown. Care should be taken to avoid surface damage when cutting the samples. Samples with obvious localized damage should not be used. Sample 1 is circular with an area of ​​S1. Samples 2, 3, 4, and 5 are annular segments with areas of S1 = 0.00281 m². 2 S2 = 0.00303 m 2 S3 = 0.00322 m 2 S4 = 0.00314 m 2 And S5=0.00304 m 2 Samples 4 and 5 are located next to sample 1.

[0030] (2) Clean the sample surface with anhydrous ethanol and dry it thoroughly.

[0031] (3) The mass ρ of the zinc layer per unit area of ​​sample No. 1 was measured by fluorescence X-ray method. i 49.425 g / m 2 Using the formula m = S i ×ρ' i The expected mass of the coating on the sample is calculated to be 0.1524 g. The weighing accuracy should be better than 0.001524 g. A balance with an accuracy of 0.001 g should be used for subsequent weighing.

[0032] (4) The masses of samples No. 2, No. 3, No. 4 and No. 5 were weighed using a balance and found to be 0.852 g, 0.856 g, 0.866 g and 0.870 g respectively.

[0033] (5) Apply a thick layer of an acid-insoluble, adhesive protective agent, such as petrolatum, to the non-test surface to ensure complete coverage and prevent contamination of the test surface. Note that the protective agent should not easily fall off during sample preparation and should cover the non-test surface throughout the process.

[0034] (6) Under room temperature conditions, completely immerse the sample coated with the protective agent in the etching solution until the coating is completely dissolved. The dissolution process is considered complete when the hydrogen evolution (violent bubbling) clearly stops. The etching solution is 3.5 g of chemically pure hexamethylenetetramine (C6H4H2O). 12 The test solution is prepared by dissolving N4 in 500 ml of concentrated hydrochloric acid (p = 1.19 g / ml) and diluting it with distilled or deionized water to 1000 ml. The volume of the test solution is usually no less than 10 ml per square centimeter of sample surface area.

[0035] (7) Remove the sample and completely remove the protective agent adhering to the unmeasured surface and the loose adhering substances adsorbed on the corroded surface. Finally, wash with ethanol, dry quickly, or use absorbent paper to remove moisture and blow dry quickly with hot air. Weigh again and the mass is 0.701 g, 0.696 g, 0.711 g, and 0.721 g respectively.

[0036] (8) The mass of zinc layer per unit area of ​​the tested surface is calculated to be 49.835 g / m². 2 49.689 g / m 2 49.363 g / m 2 49.013 g / m 2 .

[0037] (9) Calculate the reproducibility of the test results for samples 2, 3, 4, and 5: (49.835-49.013) / [(49.835+49.689+49.363+49.013) / 4]×100%=1.66%, which is less than 2%. Sample 1 can be used as a standard sample, with a zinc layer mass of 49.475 g / m² per unit area. 2 .

[0038] Although the present invention has been described in detail with reference to the accompanying drawings and preferred embodiments, the present invention is not limited thereto. Various equivalent modifications or substitutions can be made to the embodiments of the present invention by those skilled in the art without departing from the spirit and essence of the invention, and such modifications or substitutions should all be within the scope of the present invention. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should also be covered within the protection scope of the present invention.

Claims

1. A method for preparing a standard sample for testing the quality of the zinc coating in galvanized steel, characterized in that, Select a sample block to be tested and cut it into 5 pieces; sample 1 is taken from the central area of ​​the sample block and is circular; samples 2 to 5 are adjacent and are all fan-shaped, with the area denoted as S. i Samples 4 and 5 are placed next to sample 1; the mass of samples 2 through 5 is measured and recorded as m. i Then, samples 2 through 5 were subjected to etching treatment, and the mass of samples 2 through 5 after etching was recorded as m'. i Calculate the mass of zinc layer per unit area for samples 2-5 as ρ. i = ( m i - m' i )÷S i If the ratio of the range to the average value of the measurement results of samples 2 to 5 does not exceed 2%, then the average value of samples 2 to 5 shall be taken as the coating weight of sample 1, and sample 1 shall be used as the standard sample.

2. The method for preparing a standard sample for testing the quality of the zinc coating in galvanized steel as described in claim 1, characterized in that, The selected test sample should have a uniform coating and no scratches on the surface; care should be taken to avoid surface damage when cutting the sample.

3. The method for preparing a standard sample for testing the quality of the zinc coating in galvanized steel as described in claim 1, characterized in that, After cutting the sample, clean the sample surface with anhydrous ethanol and then dry it.

4. The method for preparing a standard sample for testing the quality of the zinc coating in galvanized steel as described in claim 1, characterized in that, Ensure that the weighing accuracy is better than 1% of the expected mass of the sample coating.

5. The method for preparing a standard sample for testing the quality of the zinc coating in galvanized steel as described in claim 4, characterized in that, When the mass of the sample coating is not less than 0.1 g, the weighing should be accurate to 0.001 g.

6. The method for preparing a standard sample for testing the quality of the zinc coating in galvanized steel as described in claim 3, characterized in that, The mass of the zinc layer per unit area of ​​sample 1 after cleaning was measured using the fluorescence X-ray method and denoted as ρ'1. The expected mass m of the coating on one side of the sample was calculated using the formula m = S1 × ρ'1.

7. The method for preparing a standard sample for testing the quality of the zinc coating in galvanized steel as described in claim 1, characterized in that, Before etching the sample, apply a thick layer of an acid-insoluble, adhesive protective agent to the untested surface, ensuring full coverage of the untested surface.

8. The method for preparing a standard sample for testing the quality of the zinc coating in galvanized steel as described in claim 1, characterized in that, The corrosion solution used for corrosion treatment is prepared as follows: 3.5 g of hexamethylenetetramine is dissolved in 500 ml of concentrated hydrochloric acid and diluted with distilled water or deionized water to 1000 ml.

9. A method for preparing a standard sample for testing the quality of the zinc coating in galvanized steel as described in claim 1, characterized in that, The amount of etchant used per square centimeter of sample surface area is ≥10 ml.

10. The method for preparing a standard sample for testing the quality of the zinc coating in galvanized steel as described in claim 1, characterized in that, After corrosion treatment, remove the sample and completely remove the protective agent adhering to the unmeasured surface and the loose adhering substances adsorbed on the corroded surface; finally, wash with ethanol or water and dry quickly; then weigh samples 2 to 5.

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