A method for measuring the quality of a coating on a steel product

Abstract

This invention discloses a method for determining the quality of a steel product coating, specifically: the mass of the coating in water is determined using a hydrostatic balance, and then the coating mass is calculated as: Coating mass = Mass of coating in water ÷ (1 - ρ) 水 / ρ 镀层 ) is calculated to obtain; where ρ 水 and ρ 镀层 The densities of water and the coating solution are given in g / cm³, respectively. This invention eliminates the need for sample drying before and after weighing, reducing operational steps and improving experimental efficiency. Furthermore, it minimizes sample contact with air, preventing data accuracy issues caused by product oxidation.

Description

Technical Field

[0001] This invention relates to a method for determining the coating quality of steel products, belonging to the field of testing technology. Background Technology

[0002] Currently, the main methods for determining the quality of steel product coatings are X-ray fluorescence and chemical methods. X-ray fluorescence measurement has limitations in detecting coating thickness; results outside the measurement range are inaccurate, and it is only applicable to sheet metal. The chemical method commonly used is the test method in GB / T 1839-2008. Its principle is to use the mass difference before and after coating dissolution to obtain the coating quality. In the specific test, the sample is required to be completely immersed in the coating dissolving solution at room temperature. The sample can be agitated until the coating is completely dissolved. The dissolution process is considered complete when the obvious cessation of hydrogen gas evolution (violent bubbling) is detected. Then, the sample is removed and rinsed under running water. If necessary, a nylon brush can be used to remove any loose adhering substances such as clothing from the sample surface. Finally, it is cleaned with ethanol, dried quickly, or the moisture can be absorbed with absorbent paper and then quickly dried with hot air. This method has the following drawbacks:

[0003] 1) The drying process can cause oxidation on the substrate surface, affecting the accuracy of the results;

[0004] 2) Whether the product is sufficiently dry can be judged by visual inspection, which is subjective, and any remaining moisture will affect the accuracy of the results;

[0005] 3) The process is cumbersome, and the workload is large when conducting batch experiments manually;

[0006] 4) It is not conducive to achieving process automation. Summary of the Invention

[0007] The purpose of this invention is to provide a method for determining the coating quality of steel products, which overcomes the drawbacks of existing X-ray fluorescence and chemical methods, and not only has high testing efficiency but also high testing accuracy.

[0008] To achieve the above objectives, the present invention adopts the following technical solution:

[0009] A method for determining the quality of a steel product coating specifically involves: measuring the mass of the coating in water using a hydrostatic balance, and then calculating the coating mass according to the formula: Coating mass = Mass of coating in water ÷ (1 - ρ) 水 / ρ 镀层 ) is calculated to obtain; where ρ 水 and ρ 镀层 The following are the densities of water and the coating solution, respectively, in g / cm³.

[0010] Furthermore, the density ρ of the coating solution described in this invention 镀层 The measurements were obtained using a hydrostatic balance.

[0011] Furthermore, the method for determining the quality of the coating water according to the present invention is as follows:

[0012] After cleaning, the test sample is rinsed with water and then placed in a hydrostatic balance to be weighed. The weight is recorded as m1, and the unit is g.

[0013] Immerse the sample to be tested in the coating dissolving solution until the coating is completely dissolved; remove the sample and rinse it in running water. Use a nylon brush to remove any loose adhering substances on the sample surface; clean with ethanol and rinse with water, then place it in a hydrostatic balance and weigh it, recording the weight as m2 (in grams).

[0014] Calculate m1-m2 to obtain the mass of the coating in water, in g.

[0015] Furthermore, the coating dissolving solution of the present invention is specifically as follows:

[0016] (1) For galvanized, zinc-aluminum-magnesium and tin-plated steel sheets, the coating dissolving solution is prepared by aqueous solution of hexamethylenetetramine and concentrated hydrochloric acid. For the specific formula, please refer to C.3.1 in Table A.1 of GB / T 16545-2015.

[0017] (2) For aluminum-silicon and aluminum-zinc coated steel sheets, the coating dissolving solution is prepared by aqueous solution of stannous chloride and concentrated hydrochloric acid. For specific formula, please refer to Appendix B of GB / T 36399-2018 for stannous chloride (II) solution.

[0018] Furthermore, the complete dissolution of the coating described in this invention is determined by the obvious cessation of hydrogen evolution as the end of the dissolution process.

[0019] The method of this invention can be used to determine the quality of coatings on steel plate products such as galvanized, zinc-aluminum-magnesium, aluminized silicon, aluminized zinc, and tin-plated steel.

[0020] The sample types that can be tested by the method of the present invention can be plates, wires, etc., and the sample shape is not limited within the range that can be weighed by a hydrostatic balance.

[0021] The inventive principle of the technical solution of this invention lies in:

[0022] According to Archimedes' principle, an object immersed in a still fluid (gas or liquid) experiences an upward buoyant force equal to the weight of the fluid displaced by the object, i.e., F. 浮 =G 液排 =m 液排 g=gV 排 ρ 液 The actual weight of the coating is G. 镀层 =m 镀层 g=ρ 镀层 V 镀层 g, where V 镀层 =V排 Therefore, F 浮 / G 镀层 =ρliquid / ρzinc. Further transforming the above formula, we get: 1-F 浮 / G 镀层 =Mass of coating in water / Mass of coating = 1 - ρ 液 / ρ 镀层 Furthermore, the coating quality = mass of coating in water ÷ (1 - ρ) 水 / ρ 镀层 ).

[0023] The beneficial effects of the technical solution of this invention are as follows:

[0024] 1) The method of the present invention does not require drying before and after sample weighing, which reduces the number of operation steps and improves the test efficiency;

[0025] 2) The method of the present invention reduces the contact between the sample and air, which can prevent the accuracy of the data from being affected by sample oxidation;

[0026] 3) The method of this invention is conducive to the automation of the experimental process and avoids the influence of objective factors caused by manual operation. Detailed Implementation Example 1

[0027] This embodiment measures the quality of the zinc coating on galvanized steel sheets, as detailed below:

[0028] (1) The density of the zinc bath used for coating was measured using a hydrostatic balance to obtain ρ. 镀层 =7.14 g / cm³;

[0029] (2) The galvanized steel sheet to be tested is 50×50mm in size and 1.85mm in thickness. After cleaning it, it is rinsed with pure water and then weighed in a hydrostatic balance. The weight is recorded as m1=3.718g.

[0030] (3) Immerse the galvanized steel sheet to be tested in the coating dissolving solution, which is prepared by aqueous solution of hexamethylenetetramine and concentrated hydrochloric acid. For the specific formula, please refer to C.3.1 in Table A.1 of GB / T 16545. Turn the sample over until the coating is completely dissolved. The end of the dissolution process is determined by the obvious cessation of hydrogen gas evolution (violent bubbling). Take out the sample, rinse it in running water, and use a nylon brush to remove the loose adhering substances on the surface of the sample. Clean with ethanol, rinse with water, and then weigh it in a hydrostatic balance. Record the weight as m2 = 3.568g.

[0031] (4) Calculate the mass of the coating in water = m1 - m2 = 3.718 - 3.568 = 0.150 g;

[0032] Coating quality = mass of coating in water ÷ (1 - ρ) 水 / ρ 镀层 =0.150÷(1-1 / 7.14)=0.174 g; that is, the mass of the galvanized steel sheet coating in this embodiment is 0.174 g. Example 2

[0033] This embodiment measures the quality of the coating on a galvanized aluminum-magnesium steel sheet, as detailed below:

[0034] (1) The density of the zinc bath used for coating was measured using a hydrostatic balance to obtain ρ. 镀层 =2.80 g / cm³;

[0035] (2) The galvanized aluminum-magnesium steel plate to be tested is 50×50mm in size and 2.0mm in thickness. After cleaning it, it is rinsed with pure water and then placed in a hydrostatic balance for weighing. The weight is recorded as m1=4.021g.

[0036] (3) Immerse the galvanized steel sheet to be tested in the coating dissolving solution, which is prepared by aqueous solution of hexamethylenetetramine and concentrated hydrochloric acid. For the specific formula, please refer to C.3.1 in Table A.1 of GB / T 16545. Turn the sample over until the coating is completely dissolved. The end of the dissolution process is determined by the obvious cessation of hydrogen gas evolution (violent bubbling). Take out the sample, rinse it in running water, and use a nylon brush to remove the loose adhering substances on the surface of the sample. Clean with ethanol, rinse with water, and then weigh it in a hydrostatic balance. Record the weight as m2 = 3.832 g.

[0037] (4) Calculate the mass of the coating in water = m1 - m2 = 4.021 - 3.832 = 0.189 g;

[0038] Coating quality = mass of coating in water ÷ (1 - ρ) 水 / ρ 镀层 =0.189÷(1-1 / 2.80)=0.294 g; that is, the mass of the galvanized steel sheet coating in this embodiment is 0.294 g. Example 3

[0039] This embodiment measures the quality of the coating on the aluminized zinc-coated steel sheet, as follows:

[0040] (1) The density of the zinc bath used for coating was measured using a hydrostatic balance to obtain ρ. 镀层 =7.85 g / cm³;

[0041] (2) The size of the aluminum-zinc coated steel plate to be tested is 60×60mm and the thickness is 0.7mm. After cleaning it, rinse it with pure water and then put it into a hydrostatic balance for weighing. Record it as m1=2.230g.

[0042] (3) Immerse the aluminum-zinc coated steel sheet to be tested in the coating dissolving solution, which is prepared by aqueous solution of stannous chloride and concentrated hydrochloric acid. For the specific formula, refer to the stannous chloride (II) solution in Appendix B of GB / T 36399-2018; turn the sample over until the coating is completely dissolved, and the end of the dissolution process is determined by the obvious cessation of hydrogen gas evolution (violent bubbling); take out the sample, rinse it in running water, and use a nylon brush to remove the loose adhering substances on the surface of the sample; clean with ethanol, rinse with water, and then weigh it in a hydrostatic balance, and record it as m2=2.015g;

[0043] (4) Calculate the mass of the coating in water = m1 - m2 = 2.230 - 2.015 = 0.215 g;

[0044] Coating quality = mass of coating in water ÷ (1 - ρ) 水 / ρ 镀层 =0.215÷(1-1 / 7.85)=0.246 g; that is, the mass of the galvanized steel sheet coating in this embodiment is 0.246 g.

Claims

1. A method of measuring the quality of a coating on a steel product, characterized in that, The water mass of the plating layer is measured by a hydrostatic balance, and then the plating mass is calculated according to plating mass = plating water mass ÷ (1-ρ 水 / ρ 镀层 ), i.e. obtained; wherein, ρ 水 and ρ 镀层 are densities of water and plating solution respectively, and the unit is g / cm³; The method for determining the quality of the coating in water is as follows: After cleaning, the test sample is rinsed with water and then placed in a hydrostatic balance to be weighed. The weight is recorded as m1, and the unit is g. Immerse the sample to be tested in the coating dissolving solution until the coating is completely dissolved; remove the sample and rinse it in running water. Use a nylon brush to remove any loose adhering substances on the sample surface; clean with ethanol and rinse with water, then place it in a hydrostatic balance and weigh it, recording the weight as m2 (in grams). Calculate m1-m2 to obtain the mass of the coating in water, in grams.

2. The method for determining the coating quality of steel products according to claim 1, characterized in that, Density p of the plating solution 镀层 Measured with a hydrostatic balance.

3. The method for determining the coating quality of steel products according to claim 1, characterized in that, The coating dissolving solution in step (2) is an aqueous solution of hexamethylenetetramine hydrochloric acid and an aqueous solution of stannous chloride hydrochloric acid.

4. The method for determining the coating quality of steel products according to claim 3, characterized in that, The formulation of the hexamethylenetetramine hydrochloric acid aqueous solution is shown in Table A.1, C.3.1 of GB / T 16545-2015.

5. The method for determining the coating quality of steel products according to claim 3, characterized in that, The formulation of the stannous chloride hydrochloric acid aqueous solution is as described in Appendix B of GB / T 36399-2018, which describes the stannous chloride (II) solution.

6. The method for determining the coating quality of steel products according to claim 1, characterized in that, The complete dissolution of the coating is determined by the obvious cessation of hydrogen evolution, which is considered the end of the dissolution process.

7. The method for determining the coating quality of steel products according to claim 1, characterized in that, The method is used for quality determination of coatings on galvanized, zinc-aluminum-magnesium, aluminized silicon, aluminized zinc, and tin-plated steel sheets.