Acid and alkali corrosion resistant glass lining porcelain glaze coating, preparation method and application

Abstract

The invention discloses an acid and alkali corrosion resistant glass lining ceramic glaze coating, a preparation method and application. The acid and alkali corrosion resistant glass lining ceramic glaze coating is prepared from the following raw materials: enamel glaze powder, quartz powder, clay, potassium carbonate, a coloring agent, sodium tripolyphosphate, modified zeolite, modified silica sol, calcium carbonate and nano zirconium oxide. The modified zeolite efficiently and selectively captures Fe < 2 + > by grafting phenanthroline, and performs ion exchange with Na < + >. The modified silica sol forms a firm, transparent and inorganic network structure film on the surface of the enamel coating, the film reacts with the modified zeolite to form amido bonds, the amido bonds are fixed on the surface of the enamel coating, and Fe < 2 + > is effectively prevented from being oxidized through hydrophobic modification and introduction of ascorbic acid. Calcium carbonate is used as a pore-forming agent and provides a huge loading area and a permeation channel for the modified zeolite and the modified silica sol. The nano-zirconia improves the mechanical strength of the enamel matrix on one hand, and enhances the binding force between the modified silica sol and the enamel coating through a co-condensation reaction on the other hand.

Description

Technical Field

[0001] This invention belongs to the field of enamel coating technology, specifically an acid and alkali resistant enamel coating, its preparation method, and its application. Background Technology

[0002] Enameled tanks possess high strength and excellent corrosion resistance. Their smooth, easy-to-clean surface, resistance to high temperatures and pressures, and corrosion resistance make them widely applicable in food-grade drinking water storage, wastewater treatment, and biogas projects. When storing food-grade drinking water, enamel-lined tanks typically employ food-grade enamel linings to ensure water quality safety. However, if the enamel layer has inconspicuous pinholes or cracks, or is damaged during transportation or installation due to impacts, the steel substrate, being a weak electrolyte and containing dissolved oxygen, will rapidly undergo electrochemical corrosion upon exposure to water. This generates ferrous ions (Fe2+) which enter the water and are oxidized by dissolved oxygen to ferric ions (Fe3+). These ferric ions then hydrolyze to form insoluble ferric hydroxide colloidal precipitate, further dehydrating and ultimately forming rust. This results in yellowing and turbidity of the water, and a distinct metallic taste, severely impacting the taste and sensory quality of the drinking water. Over time, this can jeopardize water quality safety. Summary of the Invention

[0003] (1) Technical problems to be solved The purpose of this invention is to provide an acid and alkali resistant enamel coating, its preparation method, and its application, in order to solve the problem of electrochemical corrosion and rust formation that occurs when steel plate substrates with imperceptible damage are exposed to water, thereby endangering water quality.

[0004] (2) Technical solution To achieve the above objectives, on the one hand, the present invention provides an acid and alkali resistant enamel coating, comprising a main material and additives, wherein the main material comprises the following raw materials in parts by weight: 70-80 parts enamel powder, 5-10 parts quartz powder, 3-5 parts clay, 1-3 parts potassium carbonate, 2-8 parts colorant, and 0.5-1.5 parts sodium tripolyphosphate. The additives include modified zeolite, modified silica sol, calcium carbonate and nano-zirconia, wherein the mass of calcium carbonate is 10-15% of the total mass of the main materials, the mass of nano-zirconia is 5% of the total mass of the main materials, and the mass ratio of modified zeolite to modified silica sol is 0.5:1. The modified zeolite is a sodium-type zeolite grafted with o-phenanthroline, and the modified silica sol is hydrophobically modified with dimethyldichlorosilane and infused with ascorbic acid.

[0005] Furthermore, the preparation method of the modified zeolite includes the following steps: S11. The sodium-type zeolite is crushed and sieved, acid-washed with dilute hydrochloric acid, then washed with deionized water until neutral, and vacuum dried to obtain pretreated zeolite. S12. Disperse the pretreated zeolite in anhydrous toluene, add APTES, reflux the reaction, wash with toluene and ethanol, and dry under vacuum to obtain aminated zeolite; S13. The aminated zeolite was ultrasonically dispersed in anhydrous DMF, 1,10-phenanthroline-5-carboxylic acid was added, followed by EDC·HCl and NHS. The mixture was stirred and reacted. The resulting reaction solution was cooled to room temperature, filtered to obtain the product, placed in a Soxhlet extractor, extracted with DMF, and vacuum dried to obtain the modified zeolite.

[0006] Furthermore, the sodium-type zeolite is sodium-type 4A zeolite with a specific surface area of ​​600 m². 2 / g.

[0007] Furthermore, the preparation method of the modified silica sol includes the following steps: S21. Mix anhydrous ethanol, hydrochloric acid, and deionized water, heat in a water bath, slowly add tetraethyl orthosilicate, and stir at a constant temperature to obtain a silicon solution. S22. Cool the silicon solution to room temperature, slowly add dimethyldichlorosilane, and stir continuously overnight at room temperature to obtain a hydrophobic silicon sol; S23. Dissolve β-cyclodextrin in deionized water by stirring, add ascorbic acid, stir the reaction, refrigerate the resulting reaction solution overnight, collect the product by filtration, wash with ice water and anhydrous ethanol alternately, and dry under vacuum to obtain ascorbic acid-β-cyclodextrin. S24. Add ascorbic acid-β-cyclodextrin to the hydrophobic silica sol, stir continuously, sonicate, and allow to stand for aging. Adjust the viscosity of the product with anhydrous ethanol to obtain the modified silica sol.

[0008] Furthermore, the obtained product is placed in a viscosity cup and its viscosity is adjusted to 20~60 mPa·s with anhydrous ethanol.

[0009] Based on the same inventive concept, in a second aspect, the present invention also provides a method for preparing an acid and alkali resistant enamel coating, applicable to the aforementioned acid and alkali resistant enamel coating, comprising the following steps: S1. Dissolve sodium tripolyphosphate in deionized water by ball milling, then add enamel glaze powder, quartz powder, clay, potassium carbonate, colorant, and nano-zirconia in sequence, and mix by ball milling. Then add calcium carbonate and continue ball milling to obtain glaze slurry. Allow it to stand and age, then spray it evenly onto low carbon steel plate. After drying, place it in a sintering furnace at 820~860℃ for sintering, and cool it to room temperature to obtain the first mixture. S2. The first mixture is ultrasonically cleaned sequentially with acetone, dilute acid, and deionized water, then cleaned and activated in a plasma cleaner, vacuum dried, immersed in modified silica gel solution for 30-60 seconds, vertically lifted, hung to dry, dried in an oven, cured at high temperature, and cooled to room temperature to obtain the second mixture. S3. Dissolve APTES in toluene solution to obtain APTES solution. Immerse the second mixture in the APTES solution and react at room temperature. Wash the product with toluene and ethanol to obtain the third mixture. S4. Dissolve the modified zeolite in PBS buffer, add EDC·HCl and NHS to obtain a modified zeolite solution, immerse the third mixture in the modified zeolite solution, react at room temperature, wash the obtained product with deionized water, and dry at low temperature to obtain a coating.

[0010] Furthermore, the vertical lifting speed is 200~300mm / min.

[0011] Based on the same inventive concept, in a third aspect, the present invention also provides an application of an acid and alkali resistant enamel coating or a preparation method for preparing a coating for drinking water tanks.

[0012] In this invention, enamel glaze powder, quartz powder, clay, potassium carbonate, colorant, and sodium tripolyphosphate are the basic raw materials for an acid and alkali resistant enamel coating. Modified zeolite, modified silica sol, calcium carbonate, and nano-zirconia are also added. Quartz powder has extremely high chemical stability, effectively resisting corrosion from almost all inorganic and organic acids except hydrofluoric acid and hot phosphoric acid. Furthermore, the added nano-zirconia itself has extremely high chemical stability to alkaline solutions, being almost insoluble in strong alkalis. Its uniform dispersion in the glass phase physically blocks and delays the dissolution of the soluble silicate network by the alkaline solution, resulting in a enamel glaze with excellent acid and alkali resistance.

[0013] Furthermore, the Zr-OH on the surface of nano-zirconia undergoes a co-condensation reaction with the Si-OH in the modified silica sol, forming a robust Si-O-Zr covalent bridge, which enhances the adhesion between the modified silica sol and the enamel coating. Calcium carbonate, acting as a pore-forming agent, decomposes during high-temperature sintering, and the resulting gas forms an open, interconnected porous structure in the coating, providing a large loading area and permeation channels for the modified zeolite and modified silica sol.

[0014] Sodium-type 4A zeolite possesses a regular channel structure and exchangeable Na+. + It can effectively capture Fe 2+ And perform 2Na + ⇌Fe 2+ Ion exchange releases Na + To prevent Fe from entering the aqueous solution. 2+ It oxidizes into Fe in water. 3+This process generates rust, thus jeopardizing water quality safety. Furthermore, by detecting Na... + An abnormally high concentration of Ca in the water serves as an indication of coating damage. To avoid excessive Ca in the water... 2+ Mg 2+ Influenced by competing ions, Fe is precisely captured. 2+ Therefore, grafting o-phenanthroline onto sodium-form 4A zeolite to form modified zeolite greatly enhances the affinity of sodium-form 4A zeolite for Fe. 2+ The selectivity, and Fe 2+ It forms an extremely stable bright red complex with phenanthroline, which on the one hand enhances Fe 2+ The fixation prevents it from flowing into the water. On the one hand, the bright red complex it generates can serve as an intuitive visual signal to locate the damage point for later maintenance.

[0015] Modified silica sol penetrates the pores created by calcium carbonate and undergoes a co-condensation reaction with the Zr-OH of nano-zirconia to enhance the bonding force, thereby forming a robust, transparent, inorganic network film on the enamel coating surface. Amide bonds are formed by the reaction of grafted amino groups with the carboxyl groups on the modified zeolite surface, thus fixing the modified zeolite to the enamel coating surface. Furthermore, the modified silica sol is hydrophobically modified with dimethyldichlorosilane, effectively blocking the penetration of moisture and dissolved oxygen, and ascorbic acid is introduced to provide a local reducing environment, preferentially reacting with oxygen and protecting Fe. 2+ It is not oxidized.

[0016] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are: 1. Modified zeolite, through grafting o-phenanthroline, efficiently and selectively captures Fe. 2+ and with Na + Ion exchange is performed to fix Fe. 2+ To prevent it from entering the water and oxidizing to form rust, which could endanger water quality, the released Na... + When it enters water, its concentration can be detected as an indicator signal of coating damage, and Fe 2+ It forms an extremely stable bright red complex with phenanthroline, which serves as an intuitive visual signal for locating damage points for later maintenance.

[0017] 2. Modified silica sol forms a robust, transparent, inorganic network film on the enamel coating surface. Amide bonds are formed by the reaction of grafted amino groups with carboxyl groups on the modified zeolite surface, thus fixing the modified zeolite to the enamel coating surface. Hydrophobic modification with dimethyldichlorosilane and the introduction of ascorbic acid effectively prevent Fe... 2+ It is oxidized.

[0018] 3. Calcium carbonate, acting as a pore-forming agent, provides a large loading area and penetration channels for modified zeolite and modified silica sol. Nano-zirconia improves the mechanical strength of the enamel matrix on the one hand, and enhances the adhesion between the modified silica sol and the enamel coating on the other hand through a co-condensation reaction. Attached Figure Description

[0019] Figure 1 This is a flowchart of the preparation process of the enamel coating in Example 1. Detailed Implementation

[0020] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] Example 1: This example discloses an acid and alkali resistant enamel coating, including main materials and additives. The main materials include the following raw materials in parts by weight: 70 parts enamel powder, 5 parts quartz powder, 3 parts clay, 1 part potassium carbonate, 2 parts colorant, and 0.5 parts sodium tripolyphosphate. The additives include modified zeolite, modified silica sol, calcium carbonate and nano-zirconia, wherein the mass of calcium carbonate is 10% of the total mass of the main materials, the mass of nano-zirconia is 5% of the total mass of the main materials, and the mass ratio of modified zeolite to modified silica sol is 0.5:1. The modified zeolite is a sodium-type zeolite grafted with o-phenanthroline, and the modified silica sol is hydrophobically modified with dimethyldichlorosilane and infused with ascorbic acid.

[0022] It should be noted that the porosity of the final coating is controlled by controlling the quality of calcium carbonate. If the amount of calcium carbonate added is less than 5% of the total mass of the main material, the porosity will be too low, and effective interconnected channels cannot be formed, which will not be effective for subsequent loading of modified zeolite and modified silica sol. If the amount of calcium carbonate added is more than 15% of the total mass of the main material, the mechanical strength and density of the enamel coating will be sacrificed, affecting its basic anti-corrosion performance.

[0023] The preparation method of the modified zeolite includes the following steps: S11. Crush and sieve the sodium-type zeolite, select particles of 160-200 mesh, wash with dilute hydrochloric acid, wash with deionized water until neutral, and vacuum dry to obtain pretreated zeolite. S12. Disperse 1g of pretreated zeolite in 20mL of anhydrous toluene, add 0.75g of APTES, reflux at 110°C for 6-12 hours, wash with toluene and ethanol, and vacuum dry to obtain aminated zeolite; S13. 1g of amino-modified zeolite was ultrasonically dispersed in 20mL of anhydrous DMF, 0.5g of 1,10-phenanthroline-5-carboxylic acid was added, followed by 0.55g of EDC·HCl and 0.33g of NHS. The mixture was stirred at 70-80°C for 12-24 hours. The resulting reaction solution was cooled to room temperature, filtered to obtain the product, placed in a Soxhlet extractor, extracted with DMF, and vacuum dried to obtain modified zeolite.

[0024] The sodium-type zeolite is sodium-type 4A zeolite with a specific surface area of ​​600 m². 2 / g.

[0025] The preparation method of the modified silica sol includes the following steps: S21. Mix 40g anhydrous ethanol, 0.1g hydrochloric acid, and 40g deionized water, heat in a 60°C water bath, slowly add 10g tetraethyl orthosilicate, and stir at a constant temperature of 60-70°C for 2-4 hours to obtain a silicon solution. S22. Cool the silicon solution to room temperature, slowly add 0.75 g of dimethyldichlorosilane, and stir continuously overnight at room temperature to obtain a hydrophobic silica sol; S23. Dissolve 10g of β-cyclodextrin in 100mL of deionized water, add 1.55g of ascorbic acid, stir at 60°C for 4-6 hours, refrigerate the resulting reaction solution at 4°C overnight, filter to collect the product, wash with ice water and anhydrous ethanol alternately, and dry under vacuum at 40-50°C to obtain ascorbic acid-β-cyclodextrin. S24. Add ascorbic acid-β-cyclodextrin to the hydrophobic silica sol, stir continuously, sonicate for 5-10 minutes, and let stand at room temperature for 12-24 hours. Adjust the viscosity of the product with anhydrous ethanol to obtain the modified silica sol.

[0026] It should be noted that ascorbic acid is encapsulated with β-cyclodextrin, which effectively isolates it from oxygen, metal ions and light, allowing ascorbic acid to be released slowly and achieving long-term antioxidant protection.

[0027] The obtained product was placed in a viscosity cup and the viscosity was adjusted to 20~60 mPa·s with anhydrous ethanol.

[0028] The method for preparing an acid and alkali resistant enamel coating includes the following steps: S1. Weigh the raw materials according to the proportion, dissolve sodium tripolyphosphate in deionized water by ball milling, add enamel glaze powder, quartz powder, clay, potassium carbonate, colorant, and nano zirconium oxide in sequence, and ball mill at 200~300 rpm for 2~4 hours. Then add calcium carbonate and continue ball milling at 100~150 rpm for 30~60 minutes to obtain glaze slurry. Seal and let stand for aging for 12~24 hours. Spray evenly onto low carbon steel plate and dry thoroughly at 80~100°C for 30 minutes. Place in a sintering furnace and sinter at 820~860°C. Cool to room temperature to obtain the first mixture. S2. The first mixture is ultrasonically cleaned sequentially with acetone, dilute acid, and deionized water, then placed in a plasma cleaner for cleaning and activation for 2-5 minutes, vacuum dried, immersed in modified silica gel solution for 30-60 seconds, vertically lifted, hung to air dry, dried in an oven, cured at 180°C, and cooled to room temperature to obtain the second mixture. S3. Dissolve APTES in toluene solution to obtain a 2% APTES solution. Immerse the second mixture in the APTES solution, seal, and react at room temperature for 12 hours. Wash the product with toluene and ethanol to obtain the third mixture. S4. Dissolve the modified zeolite in PBS buffer, add EDC·HCl and NHS to obtain a modified zeolite solution, immerse the third mixture in the modified zeolite solution, react at room temperature, wash the obtained product with deionized water, and dry at low temperature to obtain a coating.

[0029] It should be noted that the sintering furnace requires programmed temperature control. The temperature is slowly increased from room temperature to 300°C at 100°C / h; from 300 to 600°C, the temperature is increased slightly faster at 150°C / h; from 600 to 820°C, the temperature is increased rapidly at 200°C / h; finally, it is held at 820 to 860°C / h for 3 to 8 minutes. This is the critical stage for pore formation, where the glaze powder completely melts into a glassy substance, and calcium carbonate decomposes violently, generating gas and forming bubbles. After the holding time, the furnace is quickly removed and allowed to cool naturally in air. The molten glaze layer solidifies rapidly under surface tension, preserving the porous structure.

[0030] It should be noted that, as Figure 1 The diagram shows the preparation process of the enamel coating. Because organic modifiers such as o-phenanthroline and ascorbic acid are not heat-resistant, enamel glaze needs to be sintered at temperatures above 800°C. During this process, the organic modifiers completely decompose and become ineffective. Therefore, modified zeolite and modified silica sol cannot be directly added to the glaze powder for sintering. Instead, after the base glaze powder is sintered, the modified sol is extracted to penetrate into the pores created by calcium carbonate, forming a protective film on the coating surface. Then, the modified zeolite is fixed by the reaction of grafted amino groups with the carboxyl groups of the modified zeolite. The resulting coating can fix Fe... 2+ And release Na through ion exchange +As an indicator of coating damage, the modified silica sol was hydrophobically modified with dimethyldichlorosilane and infused with ascorbic acid to protect Fe. 2+ It does not oxidize and form rust, thus maintaining water quality safety.

[0031] The vertical lifting speed is 200 mm / min.

[0032] It should be noted that the film thickness formed by the modified silica sol on the enamel coating surface is controlled by adjusting the lifting speed; the faster the speed, the thicker the film. The optimal film thickness is between 0.5 and 2 μm. If the film thickness is less than 0.5 μm, it may not completely cover the uneven surface of the enamel layer, leading to defects, insufficient wear resistance and adhesion, and easy damage, thus prioritizing the protection of the substrate. If the film thickness is greater than 2 μm, the accumulation of shrinkage stress during drying and curing can easily cause the film to crack and peel off. Furthermore, after the modified zeolite is fixed, the film may lead to Na... + Slow transmission weakens the indicative function.

[0033] The application of the acid and alkali resistant enamel coating or preparation method is used to prepare coatings for drinking water tanks.

[0034] Example 2: This example is based on Example 1, but differs from Example 1 in that the main ingredients in this example include the following raw materials in parts by weight: 75 parts enamel glaze powder, 7 parts quartz powder, 4 parts clay, 2 parts potassium carbonate, 6 parts colorant, and 1 part sodium tripolyphosphate.

[0035] The other components and preparation methods are the same as in Example 1.

[0036] Example 3: This example is based on Example 1, but differs from Example 1 in that the main ingredients in this example include the following raw materials in parts by weight: 80 parts enamel glaze powder, 10 parts quartz powder, 5 parts clay, 3 parts potassium carbonate, 8 parts colorant, and 1.5 parts sodium tripolyphosphate.

[0037] The other components and preparation methods are the same as in Example 1.

[0038] Example 4: This example is based on Example 1, but differs from Example 1 in that the mass of calcium carbonate in this example is 15% of the total mass of the main material.

[0039] The other components and preparation methods are the same as in Example 1.

[0040] Example 5: This example is based on Example 1, but differs from Example 1 in that the vertical lifting speed described in this example is 300 mm / min.

[0041] The other components and preparation methods are the same as in Example 1.

[0042] Comparative Example 1: This comparative example is based on Example 1, but differs from Example 1 in that the modified zeolite in this comparative example is not grafted with o-phenanthroline.

[0043] The preparation method of the modified zeolite includes the following steps: S11. The sodium-type zeolite is crushed and sieved, and particles of 160-200 mesh are selected. The particles are washed with dilute hydrochloric acid, then washed with deionized water until neutral, and then dried under vacuum to obtain modified zeolite. The other components and preparation methods are the same as in Example 1.

[0044] Comparative Example 2: This comparative example is based on Example 1, but differs from Example 1 in that the modified silica sol in this comparative example is not grafted with dimethyldichlorosilane.

[0045] The preparation method of the modified silica sol includes the following steps: S21. Mix 40g anhydrous ethanol, 0.1g hydrochloric acid, and 40g deionized water, heat in a 60°C water bath, slowly add 10g tetraethyl orthosilicate, and stir at a constant temperature of 60-70°C for 2-4 hours to obtain a silicon solution. S22. Dissolve 10g of β-cyclodextrin in 100mL of deionized water, add 1.55g of ascorbic acid, stir at 60°C for 4-6 hours, refrigerate the resulting reaction solution at 4°C overnight, filter to collect the product, wash with ice water and anhydrous ethanol alternately, and dry under vacuum at 40-50°C to obtain ascorbic acid-β-cyclodextrin. S23. Add ascorbic acid-β-cyclodextrin to the silica sol, stir continuously, sonicate for 5-10 minutes, and let it stand at room temperature for 12-24 hours. Adjust the viscosity of the product with anhydrous ethanol to obtain the modified silica sol.

[0046] The other components and preparation methods are the same as in Example 1.

[0047] Comparative Example 3: This comparative example differs from Example 1 in that the modified silica sol in this comparative example is not grafted with ascorbic acid. The preparation method of the modified silica sol includes the following steps: S21. Mix 40g anhydrous ethanol, 0.1g hydrochloric acid, and 40g deionized water, heat in a 60°C water bath, slowly add 10g tetraethyl orthosilicate, and stir at a constant temperature of 60-70°C for 2-4 hours to obtain a silicon solution. S22. Cool the silicon solution to room temperature, slowly add 0.75g of dimethyldichlorosilane, stir continuously overnight at room temperature, and let it stand and age for 12-24 hours at room temperature. Adjust the viscosity of the product with anhydrous ethanol to obtain modified silica sol.

[0048] The other components and preparation methods are the same as in Example 1.

[0049] Comparative Example 4: This comparative example is based on Example 1, but unlike Example 1, no modified zeolite is added.

[0050] The other components and preparation methods are the same as in Example 1.

[0051] Comparative Example 5: This comparative example is based on Example 1, but unlike Example 1, no modified silica sol is added.

[0052] The other components and preparation methods are the same as in Example 1.

[0053] Comparative Example 6: This comparative example is based on Example 1, but unlike Example 1, calcium carbonate is not added to this comparative example.

[0054] The other components and preparation methods are the same as in Example 1.

[0055] Comparative Example 7: This comparative example is based on Example 1, but unlike Example 1, this comparative example does not add nano-zirconia.

[0056] The other components and preparation methods are the same as in Example 1.

[0057] Comparative Example 8: This comparative example is based on Example 1, but unlike Example 1, no quartz powder is added.

[0058] The other components and preparation methods are the same as in Example 1.

[0059] Comparative Example 9: This comparative example is a blank control group, which includes the following raw materials in parts by weight: 70 parts enamel glaze powder, 3 parts clay, 1 part potassium carbonate, 2 parts colorant, and 0.5 parts sodium tripolyphosphate.

[0060] The method for preparing an acid and alkali resistant enamel coating includes the following steps: S1. Weigh the raw materials according to the proportion, dissolve sodium tripolyphosphate in deionized water by ball milling, add enamel glaze powder, clay, potassium carbonate and colorant in sequence, ball mill at 200~300 rpm for 2~4 hours to obtain glaze slurry, seal and let stand for 12~24 hours, spray evenly onto low carbon steel plate, dry thoroughly at 80~100°C for 30 minutes, place in a sintering furnace at 820~860°C for sintering, cool to room temperature to obtain coating.

[0061] Experimental verification: 1. Acid resistance test: The test was conducted in accordance with GB / T / 9989-2005 standard. The low carbon steel plates coated with acid and alkali resistant enamel coating prepared in the examples and comparative examples were boiled in 20% hydrochloric acid solution for 48 hours, and the acid corrosion loss was measured.

[0062] 2. Alkali resistance test: The test was conducted according to GB / 7989-2003 standard. The low carbon steel plates coated with acid and alkali resistant enamel coating prepared in the examples and comparative examples were boiled in 1 mol / L sodium hydroxide solution for 48 h, and the alkali corrosion loss was measured.

[0063] 3. Sodium and Iron Ion Concentration Test: A scratch was artificially created in the central area of ​​50mm × 50mm low-carbon steel plates coated with enamel coating, prepared in each example and comparative example, exposing the underlying metal of the substrate. After soaking in drinking water for 7 days, samples were taken, and the changes in sodium and iron ion concentrations were detected using ICP-OES. The initial sodium ion concentration in the drinking water was 7–21 mg / L, and the iron ion concentration was 0.05–0.1 mg / L. The changes in sodium and iron ion concentrations in blank drinking water were simultaneously detected after 7 days. According to GB 5749-2022 drinking water standard limits, the sodium ion concentration is ≤200 mg / L, and the iron ion concentration is ≤0.3 mg / L.

[0064] 4. Visually inspect the drinking water for seven days to see if it turns yellow or becomes cloudy, and check for bright red sediment in the scratched areas.

[0065] 5. The adhesion of the enamel coating was tested using the cross-cut test.

[0066]

[0067] Table 1 shows the performance test results of the samples in each test group. Compared with Comparative Examples 7-9, Example 1 showed significantly lower acid corrosion loss and alkali corrosion loss, indicating that quartz powder can effectively resist acid corrosion. Furthermore, the addition of nano-zirconia physically blocks and delays the dissolution of the soluble silicate network by the alkali solution, resulting in good acid and alkali resistance of the prepared enamel glaze. Compared with Comparative Example 4, Example 1 showed significant sodium ion release on the seventh day, while iron ions were largely captured with little concentration change, indicating that the modified zeolite can effectively capture Fe. 2+ and Na + Ion exchange occurs, releasing Na + It was introduced into an aqueous solution. Comparing Example 1 with Comparative Examples 2-3 and 5, it can be seen that the modified silica sol, after hydrophobic modification and grafting with ascorbic acid, can effectively protect Fe. 2+It is not oxidized, thus it is captured by the modified zeolite and undergoes ion exchange. Compared with Comparative Examples 6 and 7, Example 1 showed lower adhesion, indicating that the porous structure of calcium carbonate created a better porous structure for the formation of the modified silica sol film. Furthermore, the co-condensation reaction between nano-zirconia and the modified silica sol enhanced the bonding force between the modified silica sol and the enamel coating. Compared with Comparative Example 1, Example 1 showed no bright red precipitate in the scratched area, indicating that the bright red complex formed by grafting o-phenanthroline onto sodium-type 4A zeolite can serve as a visual signal to locate the damage point for later maintenance.

[0068] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, and improvements made by those skilled in the art within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A glass-enamel glaze coating resistant to acid and alkali corrosion, characterized in that, It includes main ingredients and additives. The main ingredients include the following raw materials in parts by weight: 70-80 parts enamel glaze powder, 5-10 parts quartz powder, 3-5 parts clay, 1-3 parts potassium carbonate, 2-8 parts colorant, and 0.5-1.5 parts sodium tripolyphosphate. The additives include modified zeolite, modified silica sol, calcium carbonate and nano-zirconia, wherein the mass of calcium carbonate is 10-15% of the total mass of the main materials, the mass of nano-zirconia is 5% of the total mass of the main materials, and the mass ratio of modified zeolite to modified silica sol is 0.5:

1. The modified zeolite is a sodium-type zeolite grafted with o-phenanthroline, and the modified silica sol is hydrophobically modified with dimethyldichlorosilane and infused with ascorbic acid.

2. The acid and alkali resistant enamel coating according to claim 1, characterized in that, The preparation method of the modified zeolite includes the following steps: S11. The sodium-type zeolite is crushed and sieved, acid-washed with dilute hydrochloric acid, then washed with deionized water until neutral, and vacuum dried to obtain pretreated zeolite. S12. Disperse the pretreated zeolite in anhydrous toluene, add APTES, reflux the reaction, wash with toluene and ethanol, and dry under vacuum to obtain aminated zeolite; S13. The aminated zeolite was ultrasonically dispersed in anhydrous DMF, 1,10-phenanthroline-5-carboxylic acid was added, followed by EDC·HCl and NHS. The mixture was stirred and reacted. The resulting reaction solution was cooled to room temperature, filtered to obtain the product, placed in a Soxhlet extractor, extracted with DMF, and vacuum dried to obtain the modified zeolite.

3. The acid and alkali resistant enamel coating according to claim 2, characterized in that, The sodium-type zeolite is sodium-type 4A zeolite with a specific surface area of ​​600 m². 2 / g.

4. The acid and alkali resistant enamel coating according to claim 1, characterized in that, The preparation method of the modified silica sol includes the following steps: S21. Mix anhydrous ethanol, hydrochloric acid, and deionized water, heat in a water bath, slowly add tetraethyl orthosilicate, and stir at a constant temperature to obtain a silicon solution. S22. Cool the silicon solution to room temperature, slowly add dimethyldichlorosilane, and stir continuously overnight at room temperature to obtain a hydrophobic silicon sol; S23. Dissolve β-cyclodextrin in deionized water by stirring, add ascorbic acid, stir the reaction, refrigerate the resulting reaction solution overnight, collect the product by filtration, wash with ice water and anhydrous ethanol alternately, and dry under vacuum to obtain ascorbic acid-β-cyclodextrin. S24. Add ascorbic acid-β-cyclodextrin to the hydrophobic silica sol, stir continuously, sonicate, and allow to stand for aging. Adjust the viscosity of the product with anhydrous ethanol to obtain the modified silica sol.

5. The acid and alkali resistant enamel coating according to claim 4, characterized in that, The obtained product was placed in a viscosity cup and the viscosity was adjusted to 20~60 mPa·s with anhydrous ethanol.

6. A method for preparing an acid and alkali resistant enamel coating, applied to the preparation of an acid and alkali resistant enamel coating as described in any one of claims 1 to 5, characterized in that, The method includes the following steps: S1. Dissolve sodium tripolyphosphate in deionized water by ball milling, then add enamel glaze powder, quartz powder, clay, potassium carbonate, colorant, and nano-zirconia in sequence, and mix by ball milling. Then add calcium carbonate and continue ball milling to obtain glaze slurry. Allow it to stand and age, then spray it evenly onto low carbon steel plate. After it is completely dry, place it in a sintering furnace and sinter at 820~860℃. Cool it to room temperature to obtain the first mixture. S2. The first mixture is ultrasonically cleaned sequentially with acetone, dilute acid, and deionized water, then cleaned and activated in a plasma cleaner, vacuum dried, immersed in modified silica gel solution for 30-60 seconds, vertically lifted, hung to dry, dried in an oven, cured at high temperature, and cooled to room temperature to obtain the second mixture. S3. Dissolve APTES in toluene solution to obtain APTES solution. Immerse the second mixture in the APTES solution and react at room temperature. Wash the product with toluene and ethanol to obtain the third mixture. S4. Dissolve the modified zeolite in PBS buffer, add EDC·HCl and NHS to obtain a modified zeolite solution, immerse the third mixture in the modified zeolite solution, react at room temperature, wash the obtained product with deionized water, and dry at low temperature to obtain a coating.

7. The method for preparing an acid and alkali resistant enamel coating according to claim 6, characterized in that, The vertical lifting speed is 200~300mm / min.

8. The application of the acid and alkali resistant enamel coating according to any one of claims 1 to 5 or the method for preparing the acid and alkali resistant enamel coating according to any one of claims 6 to 7, characterized in that, Used to prepare coatings for drinking water tanks.

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