Galvanized sheet surface corrosion inhibition agent and corrosion method

Abstract

The invention discloses a medicament for corroding a surface inhibition layer of a galvanized sheet and an erosion method thereof, wherein the composition and weight percentage ratio of the medicament are: 2%-3% nitric acid, 30%-36% aluminum chloride, 0.03‰-0.05‰ calcium chloride, 1.2‰-1.7‰ hexamethylenetetramine, 30%-36% tert-butyl alcohol, 0.3‰-1.0‰ AEO-10 ​​addition, and the rest are deionized water. The components of the etchant provided by the invention are relatively stable, can be stored for a long time, can be used as needed, have high erosion efficiency, are easy to distinguish the end point of erosion of the inhibition layer, have good imaging effect on the erosion of the inhibition layer on the surface of the galvanized sheet, have little pollution, and can be widely used in the erosion of the inhibition layer on the surface of the galvanized sheet.

Description

Technical Field

[0001] The invention relates to a corrosion inhibitor for a galvanized sheet surface and an corrosion method, and belongs to the relevant field of chemical detection of galvanized sheets. Background Art

[0002] Hot-dip galvanized sheets are widely used in various fields such as automobiles and home appliances, and the inhibition layer has an important influence on the surface quality, adhesion and corrosion resistance of the zinc layer of hot-dip galvanized sheets. The quality of the inhibition layer can be observed and evaluated by scanning electron microscopy, which is divided into observation and evaluation of the inhibition layer on the surface of galvanized sheets and observation and evaluation of the inhibition layer on the cross section of galvanized sheets. Although there are corrosion methods related to the inhibition layer on the surface of galvanized sheets in the existing data, they all have certain disadvantages.

[0003] When the galvanized sheet surface is corroded by sulfuric acid etchant system and related processes, the corrosion time is at least 72 hours, the corrosion efficiency is low, and at this time there is still a large amount of visible zinc layer on the surface of the galvanized sheet; after the galvanized sheet surface is corroded by hydrochloric acid etchant system and related processes, there are large areas of crystalline particles with uneven sizes on the surface of the galvanized sheet, and the inhibition layer has a poor phase display effect; after the galvanized sheet surface is corroded by concentrated nitric acid etchant system and related processes, the etchant and the galvanized sheet undergo a violent chemical reaction, and a large amount of red-brown colored gas emerges. In addition, most of the existing materials on the corrosion inhibition layer of the galvanized sheet surface are prepared as needed, and the description of the corrosion end point is rare, very vague or avoided. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a reagent for corroding the surface inhibition layer of a galvanized sheet; the present invention also provides a method for corroding the surface inhibition layer of a galvanized sheet.

[0005] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0006] A reagent for corroding a surface inhibition layer of a galvanized sheet, the components of the reagent and their weight percentage ratios are: 2%-3% nitric acid, 30%-36% aluminum chloride, 0.03‰-0.05‰ calcium chloride, 1.2‰-1.7‰ hexamethylenetetramine, 30%-36% tert-butyl alcohol, 0.3‰-1.0‰ AEO-10 ​​addition, and the rest is deionized water.

[0007] The preparation solvent of the medicament of the present invention is water, and the total amount of the medicament added to each liter of water is 206-210g.

[0008] The mechanism of action of each component of the medicament of the present invention is:

[0009] Nitric acid has both certain acidity and certain oxidizing properties. The acidity of nitric acid can dissolve the zinc layer, and its oxidizing property can cause a certain oxidation on the surface of iron and aluminum atoms at a microscopic level, which can alleviate the chemical reaction between the hydrogen ions in the acid and the inhibition layer (mainly composed of iron and aluminum elements) on the surface of the steel substrate to a certain extent, so that the erosion of the inhibition layer on the surface of the galvanized sheet by nitric acid will not be too intense.

[0010] Aluminum chloride: Under the current nitric acid concentration, if the hydrogen ions in the nitric acid corrode the inhibition layer on the surface of the galvanized sheet for too long, the hydrogen ions will further react with the iron and aluminum elements in the inhibition layer, and the aluminum element will lose electrons to generate aluminum ions. However, if the aluminum ion concentration in the solution is too high, it will inhibit the reaction rate of hydrogen ions and aluminum atoms to a certain extent, giving the corrosion personnel of the inhibition layer more time to judge the end point of corrosion.

[0011] Calcium chloride: Calcium chloride is a relatively easy-to-obtain and inexpensive reagent in the laboratory. At the same time, calcium ions have a large ionic radius, which can prevent the various ions in the solution from aggregating and precipitating from the solution during long-term storage, thereby increasing the long-term storage time of the solution. The presence of this solute does not affect the corrosion effect of the entire corrosive agent system on the surface of the galvanized sheet.

[0012] Hexamethylenetetramine: Hexamethylenetetramine belongs to the mechanism of action of adsorption film type corrosion inhibitor, which can cover the surface of the inhibition layer and slow down the corrosion rate of nitric acid on the inhibition layer.

[0013] Tert-butyl alcohol: As an organic solvent in the solution, tert-butyl alcohol can slow down the reaction rate of the effective solute nitric acid on the metal material, making the entire chemical reaction milder, thereby obtaining a better inhibition layer morphology. In addition, tert-butyl alcohol has no α-carbon hydrogen atoms, a stable chemical structure, is not affected by the strong oxidizing property of nitric acid, and can be stored in the solution for a long time.

[0014] AEO-10: As a nonionic surfactant, AEO-10 ​​is soluble in water and has a good function of wetting the surface of the test sample, which can obtain a good effect of inhibiting layer erosion. In addition, the agent has a hard water resistance function and can be stored for a long time in the erosion agent system.

[0015] The preparation method of the medicament of the present invention is as follows:

[0016] Take 75% to 85% of the total water volume, add hexamethylenetetramine to it, stir to dissolve, then add AEO-10, stir to dissolve; then add nitric acid, aluminum chloride, calcium chloride, tert-butanol in sequence, stir to dissolve; finally add the remaining amount of water and stir evenly.

[0017] Furthermore, the water temperature of the water in the present invention is 28-33°C.

[0018] The present invention also provides a method for corrosion of the surface inhibition layer of a galvanized sheet, which is as follows: using trichlorotrifluoroethane to remove impurities on the surface of a sample to be tested, placing the sample in a magnetic stirrer, adding an etchant, the speed of the magnetic stirrer is 100r / min-300r / min, and the heating temperature is 28-33°C; when the reaction bubble speed on the surface of the galvanized sheet begins to slow down and becomes matte gray, the reaction is terminated; immediately taking out the sample, washing the surface of the sample with a large amount of alcohol, and drying it with cold air from a hair dryer.

[0019] Furthermore, the sample to be tested in the present invention is circular, and its diameter is 5mm-15mm.

[0020] The present invention sets the reaction temperature to 28-33°C because if the reaction temperature is too high, the corrosive agent and the sample to be tested will react violently, resulting in excessive erosion of the inhibition layer and even exposure of the steel substrate.

[0021] The beneficial effects of the above technical solution are as follows: nitric acid can effectively remove the zinc layer, slow down the corrosion rate of the inhibition layer, and effectively protect the initial content of each element in the inhibition layer; similarly, aluminum chloride in the solution can prevent the inhibition layer from being corroded by acid, and effectively protect the initial content of each element in the inhibition layer; calcium chloride can effectively increase the stability of the solution without affecting the corrosion effect of the agent on the surface of the galvanized sheet; hexamethylenetetramine can be adsorbed on the metal surface, slowing down the corrosion rate of nitric acid on the inhibition layer; tert-butyl alcohol can slow down the corrosion rate of acid on the metal material on the one hand, and can be stored for a long time in the mixed agent system on the other hand; AEO-10 ​​can make the corrosive agent quickly "spread" on the surface of the metal material, thereby obtaining an excellent corrosion phase of the inhibition layer, and can coexist with the entire corrosive agent system for a long time.

[0022] The components of the etchant provided by the present invention are relatively stable, can be stored for a long time, can be used at any time, have high etch efficiency, are easy to judge the end point of etch of the inhibition layer, have good imaging effect on etch of the inhibition layer on the surface of galvanized sheet, have little pollution, and can be widely used in etch of the inhibition layer on the surface of galvanized sheet. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is the field emission scanning electron microscope image of Example 1 (10,000 times).

[0024] Figure 2 This is the field emission scanning electron microscope image of Example 2 (10,000 times).

[0025] Figure 3 This is the field emission scanning electron microscope image of Example 3 (10,000 times).

[0026] Figure 4 This is a field emission scanning electron microscope image of Example 4 (10,000 times).

[0027] Figure 5 This is the field emission scanning electron microscope image of Example 5 (10,000 times). DETAILED DESCRIPTION

[0028] The present invention is further described in detail below in conjunction with specific implementation modes.

[0029] The invention provides a medicament for corroding a surface inhibition layer of a galvanized sheet, wherein the ingredients and weight percentage of the medicament are: 2%-3% nitric acid, 30%-36% aluminum chloride, 0.03‰-0.05‰ calcium chloride, 1.2‰-1.7‰ hexamethylenetetramine, 30%-36% tert-butyl alcohol, 0.3‰-1.0‰ AEO-10 ​​addition amount, and the rest is deionized water. The total amount of the medicament added per liter of water is 206-210g.

[0030] The preparation method of the medicament is as follows:

[0031] Take 75% to 85% of the total water volume, the water temperature is 28-33℃, add hexamethylenetetramine, stir to dissolve, then add AEO-10, stir to dissolve; then add nitric acid, aluminum chloride, calcium chloride, tert-butanol in sequence, stir to dissolve; finally add the remaining amount of water and stir evenly.

[0032] The present invention also provides a method for eroding the surface inhibition layer of a galvanized sheet, which is as follows: using trichlorotrifluoroethane to remove impurities on the surface of the sample to be tested, placing the sample in a magnetic stirrer, adding an etchant, the speed of the magnetic stirrer is 100r / min-300r / min, and the heating temperature is 28-33°C; when the reaction bubble speed on the surface of the galvanized sheet begins to slow down and becomes matte gray, the reaction is terminated; immediately take out the sample, rinse the surface of the sample with a large amount of alcohol, and dry it with cold air from a hair dryer. Preferably, the sample to be tested is a circle with a diameter of 5mm-15mm.

[0033] Examples 1-5

[0034] Different brands of DC51D+Z, HC220YD+Z, HC260LAD+Z, HC340 / 590DP, and HC650 / 980DPD+Z produced by a certain company were selected as test materials for erosion test. The contents of each component in the reagents used in each embodiment are shown in Table 1.

[0035] Table 1 Content of each component of the medicine used in each example

[0036]

[0037] The etching process of each embodiment is shown in Table 2.

[0038] Table 2 Etching process of each embodiment

[0039]

[0040] The field emission scanning electron microscope images of the samples of each embodiment are shown in Figure 1-Figure 5 ; Energy spectrum was used to detect the Al atomic percentage, and the results are shown in Table 3.

[0041] Table 3 Electron microscopy test results of various examples

[0042]

[0043] It can be clearly seen from the scanning electron microscope images and test results of Examples 1-5 that the etchant provided by the present invention can obtain good inhibition layer corrosion morphology by chemically etching different grades of galvanized sheets, and the Al atomic percentage in each inhibition layer is relatively high, ranging from 16.00 to 20.85, which is higher than the test values ​​in most literatures, indicating that the method adopted in this application document has little damage to the inhibition layer and more scientifically reflects the original physical and chemical information of the inhibition layer.

[0044] The above embodiments are only used to illustrate rather than limit the technical solutions of the present invention. Although the present invention is described in detail with reference to the above embodiments, those skilled in the art should understand that the present invention can still be modified or replaced by equivalents. Any modification or partial replacement that does not depart from the spirit and scope of the present invention should be included in the scope of the claims of the present invention.

Claims

1. A reagent for corroding the surface inhibition layer of a galvanized sheet, characterized in that: The ingredients of the agent and their weight percentage ratios are: 2%-3% nitric acid, 30%-36% aluminum chloride, 0.03‰-0.05‰ calcium chloride, 1.2‰-1.7‰ hexamethylenetetramine, 30%-36% tert-butanol, 0.3‰-1.0‰ AEO-10 ​​addition, and the rest is deionized water; the main components of the inhibition layer are iron and aluminum.

2. The agent for corroding the surface inhibition layer of galvanized sheet according to claim 1, characterized in that: The preparation solvent of the agent is water, and the total amount of the agent added per liter of water is 206-210g.

3. The agent for corroding the surface inhibition layer of galvanized sheet according to claim 1, characterized in that: The preparation method of the agent is as follows: take 75% to 85% of the total water volume, add hexamethylenetetramine thereto, stir to dissolve, then add AEO-10, stir to dissolve; then add nitric acid, aluminum chloride, calcium chloride, tert-butanol in sequence, stir to dissolve; finally add the remaining amount of water and stir evenly.

4. A method for inhibiting corrosion of a galvanized sheet surface layer, characterized in that: The method is as follows: using trichlorotrifluoroethane to remove impurities on the surface of the sample to be tested, placing the sample in a magnetic stirrer, adding the agent described in claim 1, the speed of the magnetic stirrer is 100r / min-300r / min, and the heating temperature is 28-33°C; when the reaction bubble speed on the surface of the galvanized sheet begins to slow down and becomes matte gray, the reaction is terminated; immediately take out the sample, rinse the surface of the sample with a large amount of alcohol, and blow dry it with cold air from a hair dryer.

5. The method for inhibiting corrosion of the surface layer of a galvanized sheet according to claim 4, characterized in that: The sample to be tested is circular, and its diameter is 5mm-15mm.

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