Corrosion-resistant enamel material and method for producing same

Abstract

This invention belongs to the field of enamel material preparation technology, specifically relating to a corrosion-resistant enamel material and its preparation method. The corrosion-resistant enamel material of this invention comprises a Q345R low-alloy steel substrate and an enamel coating; wherein the enamel coating consists of a base glaze layer and a top glaze layer. The base glaze layer is composed of glaze A, silica, and quartz powder; the top glaze layer is composed of glaze B, modified nano-sepiolite, and magnesium aluminum spinel micro powder. The corrosion-resistant enamel material of this invention uses a Q345R low-alloy steel substrate as the base material and a composite coating consisting of a base glaze and a top glaze as the enamel coating. The base glaze layer is tightly adhered to the surface of the Q345R low-alloy steel substrate, achieving a tight bond between the enamel coating and the substrate, and serving as an interlayer transition. The top glaze layer covers the base glaze layer and mainly serves a corrosion-resistant function. Through the synergistic function of the base glaze and the top glaze, corrosion protection of the substrate is achieved.

Description

Technical Field

[0001] This invention belongs to the field of enamel material preparation technology, specifically relating to a corrosion-resistant enamel material and its preparation method. Background Technology

[0002] Enamel is a composite material composed of an inorganic coating and a metal substrate. It is made by coating a metal substrate with a vitreous inorganic material and then firing it at high temperatures, fusing the two together to form a new type of composite material that is corrosion-resistant, high-temperature resistant, wear-resistant, and has a smooth and clean surface. The enamel is mainly composed of feldspar, quartz, and other minerals and various chemical auxiliary raw materials mixed in a specific ratio and then melted at high temperatures. It is a colorless or colored glassy thin layer covering the surface of enamel products, with regularly organized molecular groups, combining the advantages of both metal and glass.

[0003] As a composite material composed of metals and inorganic materials, enamel has significantly superior performance compared to purely metallic or inorganic materials. This excellent performance determines the wide range of applications for enamel, which currently plays an irreplaceable role in the construction industry, petrochemical industry, and traditional daily necessities.

[0004] The properties of enamel materials are closely related to the metal substrate and the inorganic coating. Different substrate types require different enamel glazes. In certain applications within the petrochemical industry (such as pressure vessels commonly used in chemical processing), enamel materials need to possess excellent resistance to acid and alkali corrosion. However, due to the harsh application environment, enamel materials suffer severe corrosion. Therefore, it is necessary to properly match the metal substrate and the enamel glaze to achieve excellent acid and alkali corrosion resistance, thereby extending the service life of the enamel material. Summary of the Invention

[0005] The purpose of this invention is to provide a corrosion-resistant enamel material. This corrosion-resistant enamel material exhibits excellent resistance to acid and alkali corrosion. Furthermore, this invention also provides a method for its preparation.

[0006] The corrosion-resistant enamel material of this invention comprises a Q345R low-alloy steel substrate and an enamel coating. The enamel coating consists of a base glaze layer and a top glaze layer. The base glaze layer, by weight, comprises 100 parts of glaze A, 0.35-0.4 parts of fumed silica, and 3.0-4.0 parts of quartz powder. Glaze A, by weight, comprises the following raw materials: 62-64 parts of silicon dioxide, 5.5-6.0 parts of alumina, 12-14 parts of boron trioxide, 2.5-3.5 parts of phosphorus pentoxide, 4.0-4.5 parts of strontium borate, 3.3-3.5 parts of lithium metaborate, and 2.8-... The surface glaze layer, by weight, consists of 100 parts of glaze B, 3.6-3.8 parts of modified nano-sepiolite, and 2.8-3.0 parts of magnesium aluminum spinel micro powder. Glaze B, by weight, consists of the following raw materials: 65-67 parts of silicon dioxide, 6.5-7.0 parts of alumina, 11-13 parts of boron trioxide, 3.5-3.7 parts of lithium silicate, 1.2-1.4 parts of sodium bismuthate, 2.6-2.8 parts of zinc fluorosilicate, 3.0-3.2 parts of potassium hexatitanate, and 3.4-3.6 parts of lanthanum metatantalate.

[0007] The chemical composition of the Q345R low-alloy steel substrate, by mass percentage, is as follows: C 0.12-0.14%, Si 0.45-0.50%, Mn 1.20-1.70%, P 0.016-0.020%, S 0.005-0.008%, Cu 0.07-0.09%, Ni 0.05-0.08%, Cr 0.05-0.08%, Mo 0.03-0.05%, with Fe as the balance.

[0008] Preferably, the chemical composition of the Q345R low alloy steel substrate, by mass percentage, is: C 0.12%, Si 0.47%, Mn 1.53%, P 0.018%, S 0.005%, Cu 0.07%, Ni 0.05%, Cr 0.05%, Mo 0.03%, with Fe as the balance.

[0009] The particle size of the magnesium aluminum spinel powder in the glaze layer is 2.5-3.0 micrometers.

[0010] The preparation method of modified nano-sepiolite in the glaze layer consists of the following steps: ① Adding nano-sepiolite to deionized water and ultrasonically dispersing it to prepare a suspension; ② Adding hydrochloric acid solution to the above suspension and stirring the mixture in a constant temperature water bath at 50℃ for 5 hours; ③ After the reaction is completed, vacuum filtering is performed to obtain a solid product, which is then washed until the pH value of the filtrate is 7.0 and no white precipitate is formed upon addition of silver nitrate solution; ④ The washed product is placed in a freeze dryer for drying; ⑤ The dried product is ground using a planetary ball mill to prepare modified nano-sepiolite.

[0011] In step ① of the preparation method of modified nano-sepiolite, the weight ratio of nano-sepiolite to deionized water is 1:12.

[0012] In step ① of the preparation method of modified nano-sepiolite, the ultrasonic dispersion power is 300W and the ultrasonic dispersion time is 30min.

[0013] In step ② of the preparation method of modified nano-sepiolite, the concentration of hydrochloric acid solution is 1.5 mol / L, and the weight ratio of hydrochloric acid solution to nano-sepiolite is 8:1.

[0014] In step ② of the preparation method of modified nano-sepiolite, the stirring speed is 300 r / min.

[0015] In step ③ of the preparation method of modified nano-sepiolite, the washing is performed by washing five times with a mixture of deionized water and anhydrous ethanol at a volume ratio of 1:1.

[0016] The drying process described in step ④ of the preparation method of modified nano-sepiolite is drying at -40℃ and 10Pa vacuum for 12 hours.

[0017] In step ⑤ of the preparation method of modified nano-sepiolite, the ball-to-material ratio during grinding is 10:1, the rotation speed is 250 r / min, and the grinding time is 30 min.

[0018] The method for preparing the corrosion-resistant enamel material of the present invention comprises the following steps: (1) Prepare the raw materials of glaze A according to the formula and mix them in a ball mill for 2.5-3 hours. Melt and quench the mixed powder to form glass glaze block A. Ball mill the glass glaze block A for 2.0-2.5 hours and pass it through a 200-mesh sieve to prepare glaze A. (2) Mix glaze A, white carbon black and quartz powder evenly to obtain mixed powder. Mix the mixed powder with deionized water and stir. Let it stand until the bubbles escape to form a slurry to prepare the base glaze slurry. (3) Prepare the raw materials of glaze B according to the formula and mix them in a ball mill for 2.5-3 hours. Melt and quench the mixed powder to form glass glaze block B. Ball mill the glass glaze block B for 1.8-2.0 hours and pass it through a 200-mesh sieve to prepare glaze B. (4) Mix glaze B, modified nano sepiolite and magnesium aluminum spinel powder evenly to obtain mixed powder. Mix the mixed powder with deionized water and stir. Let it stand until the bubbles escape to form a slurry to prepare the surface glaze slurry. (5) The Q345R low alloy steel substrate is subjected to alkaline immersion degreasing, pickling derusting, passivation, rinsing and drying to prepare a pretreated Q345R low alloy steel substrate. (6) Spray the base glaze evenly on the surface of the pretreated Q345R low alloy steel substrate, let it stand at room temperature for 8-10 minutes to level, and then dry it. Spray the top glaze evenly on the dried base glaze surface, let it stand at room temperature for 8-10 minutes again, and then dry it to obtain the coated workpiece. (7) The coated workpiece is sent into a firing kiln and kept at 890-900℃ for 18-20 minutes to prepare corrosion-resistant enamel material.

[0019] In step (1), the powder melting temperature is 1210-1220℃ and the melting time is 40-45min.

[0020] In step (2), the mass ratio of the mixed powder to deionized water is 2.0-2.2:1.

[0021] In step (3), the melting temperature is 1230-1240℃ and the melting time is 30-35min.

[0022] In step (4), the mass ratio of the mixed powder to deionized water is 2.3-2.4:1.

[0023] In step (5), the alkaline immersion degreasing uses a composite strong alkali degreasing solution. The chemical composition of the composite strong alkali degreasing solution is: 27g of sodium hydroxide, 38g of sodium carbonate, and 17g of trisodium phosphate per liter of aqueous solution. The Q345R low alloy steel substrate is immersed in the composite strong alkali degreasing solution at 57°C for 18 minutes. After removal, it is rinsed with flowing deionized water for 3 minutes until the pH of the rinsing solution is 7.0. The pickling rust removal uses a mixed pickling solution, which is a 6% (w / w) dilute hydrochloric acid aqueous solution. 0.4g of hexamethylenetetramine is added to each liter of the dilute hydrochloric acid aqueous solution. The substrate is immersed in the mixed pickling solution at room temperature for 10 minutes. After pickling, it is rinsed with flowing deionized water for 3 minutes until the pH of the rinsing solution is 7.0. The passivation treatment uses an 8% (w / w) phosphoric acid aqueous solution and is passivated at room temperature for 8 minutes. The rinsing is performed after passivation by rinsing with flowing deionized water for 50 seconds. The drying treatment is performed after rinsing by placing the substrate in an oven and drying it at 130°C for 35 minutes.

[0024] In step (6), the base glaze is sprayed and the wet film thickness is controlled at 0.33 mm. After standing at room temperature and leveling, it is dried at 100-110℃ for 25-35 min.

[0025] In step (6), the surface glaze is sprayed and the wet film thickness is controlled at 0.27 mm. After leveling at room temperature, it is dried at 100-110℃ for 25-35 min.

[0026] In step (7), the temperature is increased from room temperature to 890-900℃ at a heating rate of 3℃ / min.

[0027] Compared with the prior art, the present invention has the following advantages: (1) The corrosion-resistant enamel material of the present invention uses Q345R low alloy steel substrate as the base and a composite coating composed of base glaze and top glaze as the enamel coating. The base glaze layer is tightly attached to the surface of Q345R low alloy steel substrate to achieve a tight bond between the enamel coating and the substrate and play a role in interlayer transition. The top glaze layer covers the base glaze layer and mainly plays a role in corrosion resistance. Through the functional synergy of the base glaze and top glaze, corrosion protection of the substrate is achieved.

[0028] (2) In the corrosion-resistant enamel material of the present invention, a borosilicate glass network framework is constructed in the base glaze A using SiO2, Al2O3, and B2O3. A mixture of P2O5, strontium borate, and lithium metaborate is used as a flux to promote the disintegration of Si-O bonds, thereby accelerating the chemical reaction rate of the melt at high temperatures. A mixture of manganese tetroxide, bismuth vanadate, and barium molybdate is used as an adhesive. During the firing process, Mn... 3+ / Mn 2+ Variable valence ions promote redox reactions on the substrate surface, forming a rough interface morphology that enhances the adhesion between the base glaze and the substrate through mechanical anchoring. They also promote the dissolution of FeO from the substrate surface into the glaze, optimizing the interface transition layer and improving chemical bonding stability. Bismuth vanadate decomposes into Bi₂O₃ and V₂O₅ at high temperatures. Bi₂O₃ acts as a flux, significantly reducing the surface tension and viscosity of the glaze melt, promoting uniform glaze spreading and improving glaze density. V₂O₅ acts as an auxiliary fluxing component, optimizing the glaze's melting properties. Barium molybdate decomposes at high temperatures to generate BaO and MoO₃. MoO₃ reacts with FeO generated from oxidation on the substrate surface to form an iron-molybdate transition layer. This transition layer's crystal structure has good compatibility with both metal and borosilicate glass glazes, providing strong chemical bonding.

[0029] (3) The corrosion-resistant enamel material of the present invention also contains silica and quartz powder in the base glaze layer. The quartz powder is micron-sized crystalline quartz powder, which is used to control the thermal expansion coefficient and high-temperature melt viscosity of the base glaze, prevent excessive dripping of the base glaze during firing, and buffer thermal stress and reduce microcracks in the glaze layer. The silica is nano-sized amorphous silica, which is only used to improve the thixotropy and suspension stability of the glaze slurry.

[0030] (4) In the corrosion-resistant enamel material of the present invention, the glaze B of the surface glaze layer is constructed with silica, alumina and boron trioxide to form a stable borosilicate-oxygen skeleton, providing basic corrosion resistance and structural strength for the glaze layer; lithium silicate and sodium bismuthate are used as composite fluxes to regulate the melting temperature and high-temperature fluidity of the glaze, promoting uniform leveling of the glaze surface. A mixture of zinc fluorosilicate, potassium hexatitanate and lanthanum metatantalate is used as filler to give it excellent corrosion resistance. Among them, potassium hexatitanate crystals have a unique tunnel structure and the particles have a natural needle-like morphology, which can be uniformly dispersed in the enamel glaze layer. By extending the penetration path of the corrosive medium, it can improve the barrier performance. Its high melting point characteristics ensure structural stability during the firing process, providing physical toughening and corrosion inhibition for the glaze layer. Lanthanum metatantalate, as a corrosion-resistant functional phase, has excellent resistance to strong acids and strong alkalis, which can improve the local corrosion resistance threshold of the glaze layer. The La it contains 3+ As a high-field-strength network modifier, its high charge density enables it to strongly electrostatically bind non-bridging oxygen, reducing the mobility of alkali metal ions. Simultaneously, the large ionic radius increases the glass network packing density, improving the glaze's density and chemical inertness. During firing, zinc fluorosilicate decomposes into zinc fluoride and silicon tetrafluoride gases. Silicon tetrafluoride volatilizes and escapes, while zinc fluoride melts at 872°C and becomes miscible with the glass melt. The released Zn... 2+ Ions are embedded in the borosilicate network framework in a four-coordinated [ZnO4] configuration, forming Si-O-Zn bridges, increasing network connectivity and improving the density of the glaze layer. Simultaneously, Zn... 2+ The electrostatic binding effect on nearby alkali metal ions reduces their mobility and minimizes microscopic defects caused by ion migration. Together with the physical barrier effect of potassium hexatitanate whiskers and the chemical inertness of lanthanum metatantalate, they jointly block the penetration channels of corrosive media.

[0031] (5) The corrosion-resistant enamel material of the present invention further includes modified nano-sepiolite and magnesium aluminum spinel micro powder in the surface glaze. In addition to regulating the fluidity of the surface glaze, the modified nano-sepiolite also has the following effects: sepiolite is a one-dimensional nanorod silicate. When the corrosive medium attempts to penetrate the glaze layer, these nanorods will significantly extend the penetration path of the corrosive medium, thereby further improving the acid resistance, chloride ion resistance and humid heat corrosion resistance of the surface glaze. Moreover, the modified nano-sepiolite can also hinder the expansion of microcracks inside the glaze layer, play a toughening role, and improve the crack resistance of the glaze layer. Magnesium aluminum spinel micro powder is a rigid inert micro powder that optimizes the rheological properties of the glaze slurry. During the firing process, magnesium aluminum spinel regulates the thermal expansion gradient of the surface glaze with an ultra-low expansion rigid skeleton, inhibiting the generation of macro cracks. At the same time, the high-temperature skeleton of spinel prevents the glaze layer from sagging, and the sepiolite-derived liquid phase promotes the high-temperature smoothing of the glaze surface. The combination of the two synergistically improves the density, acid and alkali corrosion resistance and mirror smoothness of the glaze layer.

[0032] (6) The method for preparing corrosion-resistant enamel material according to the present invention is simple, the parameters are easy to control, and the corrosion-resistant enamel material prepared is stable. Detailed Implementation

[0033] Example 1

[0034] The corrosion-resistant enamel material described in Example 1 is composed of a Q345R low-alloy steel substrate and an enamel coating. The enamel coating consists of a base glaze layer and a top glaze layer. The base glaze layer, by weight, comprises 100 parts of glaze A, 0.37 parts of silica, and 3.5 parts of quartz powder. Glaze A, by weight, comprises the following raw materials: 63 parts of silicon dioxide, 5.7 parts of alumina, 13 parts of boron trioxide, 3.0 parts of phosphorus pentoxide, 4.3 parts of strontium borate, and 3.4 parts of lithium metaborate. The surface glaze layer, by weight, consists of 100 parts of glaze B, 3.7 parts of modified nano-sepiolite, and 2.9 parts of magnesium aluminum spinel micro powder. Glaze B, by weight, consists of the following raw materials: 66 parts of silicon dioxide, 6.7 parts of alumina, 12 parts of boron trioxide, 3.6 parts of lithium silicate, 1.3 parts of sodium bismuthate, 2.7 parts of zinc fluorosilicate, 3.1 parts of potassium hexatitanate, and 3.5 parts of lanthanum metatantalate.

[0035] The chemical composition of the Q345R low alloy steel substrate, by mass percentage, is: C 0.12%, Si 0.47%, Mn 1.53%, P 0.018%, S 0.005%, Cu 0.07%, Ni 0.05%, Cr 0.05%, Mo 0.03%, with Fe as the balance.

[0036] The particle size of the magnesium aluminum spinel powder in the surface glaze layer is 2.7 micrometers.

[0037] The preparation method of modified nano-sepiolite in the glaze layer consists of the following steps: ① Adding nano-sepiolite to deionized water and ultrasonically dispersing it to prepare a suspension; ② Adding hydrochloric acid solution to the above suspension and stirring the mixture in a constant temperature water bath at 50℃ for 5 hours; ③ After the reaction is completed, vacuum filtering is performed to obtain a solid product, which is then washed until the pH value of the filtrate is 7.0 and no white precipitate is formed upon addition of silver nitrate solution; ④ The washed product is placed in a freeze dryer for drying; ⑤ The dried product is ground using a planetary ball mill to prepare modified nano-sepiolite.

[0038] In step ① of the preparation method of modified nano-sepiolite, the weight ratio of nano-sepiolite to deionized water is 1:12.

[0039] In step ① of the preparation method of modified nano-sepiolite, the ultrasonic dispersion power is 300W and the ultrasonic dispersion time is 30min.

[0040] In step ② of the preparation method of modified nano-sepiolite, the concentration of hydrochloric acid solution is 1.5 mol / L, and the weight ratio of hydrochloric acid solution to nano-sepiolite is 8:1.

[0041] In step ② of the preparation method of modified nano-sepiolite, the stirring speed is 300 r / min.

[0042] In step ③ of the preparation method of modified nano-sepiolite, the washing is performed by washing five times with a mixture of deionized water and anhydrous ethanol at a volume ratio of 1:1.

[0043] The drying process described in step ④ of the preparation method of modified nano-sepiolite is drying at -40℃ and 10Pa vacuum for 12 hours.

[0044] In step ⑤ of the preparation method of modified nano-sepiolite, the ball-to-material ratio during grinding is 10:1, the rotation speed is 250 r / min, and the grinding time is 30 min.

[0045] The method for preparing the corrosion-resistant enamel material described in Example 1 consists of the following steps: (1) The raw materials of glaze A are prepared according to the formula and mixed in a ball mill for 2.7 hours. The mixed powder is melted and quenched in water to form glass glaze block A. Glass glaze block A is ball-milled for 2.3 hours and passed through a 200-mesh sieve to prepare glaze A. (2) Mix glaze A, white carbon black and quartz powder evenly to obtain mixed powder. Mix the mixed powder with deionized water and stir. Let it stand until the bubbles escape to form a slurry to prepare the base glaze slurry. (3) The raw materials of glaze B are prepared according to the formula and mixed in a ball mill for 2.7 hours. The mixed powder is melted and quenched in water to form glass glaze block B. Glass glaze block B is ball-milled for 1.9 hours and passed through a 200-mesh sieve to prepare glaze B. (4) Mix glaze B, modified nano sepiolite and magnesium aluminum spinel powder evenly to obtain mixed powder. Mix the mixed powder with deionized water and stir. Let it stand until the bubbles escape to form a slurry to prepare the surface glaze slurry. (5) The Q345R low alloy steel substrate is subjected to alkaline immersion degreasing, pickling derusting, passivation, rinsing and drying to prepare a pretreated Q345R low alloy steel substrate. (6) Spray the base glaze evenly on the surface of the pretreated Q345R low alloy steel substrate, let it stand at room temperature for 9 minutes to level and then dry it. Spray the top glaze evenly on the dried base glaze surface, let it stand at room temperature for 9 minutes again and then dry it to obtain the coated workpiece. (7) The coated workpiece is sent into a firing kiln and held at 895℃ for 19 minutes to prepare corrosion-resistant enamel material.

[0046] In step (1), the powder melting temperature is 1215℃ and the melting time is 43min.

[0047] In step (2), the mass ratio of the mixed powder to deionized water is 2.1:1.

[0048] In step (3), the melting temperature is 1235℃ and the melting time is 33min.

[0049] In step (4), the mass ratio of the mixed powder to deionized water is 2.35:1.

[0050] In step (5), the alkaline immersion degreasing uses a composite strong alkali degreasing solution. The chemical composition of the composite strong alkali degreasing solution is: 27g of sodium hydroxide, 38g of sodium carbonate, and 17g of trisodium phosphate per liter of aqueous solution. The Q345R low alloy steel substrate is immersed in the composite strong alkali degreasing solution at 57°C for 18 minutes. After removal, it is rinsed with flowing deionized water for 3 minutes until the pH of the rinsing solution is 7.0. The pickling rust removal uses a mixed pickling solution, which is a 6% (w / w) dilute hydrochloric acid aqueous solution. 0.4g of hexamethylenetetramine is added to each liter of the dilute hydrochloric acid aqueous solution. The substrate is immersed in the mixed pickling solution at room temperature for 10 minutes. After pickling, it is rinsed with flowing deionized water for 3 minutes until the pH of the rinsing solution is 7.0. The passivation treatment uses an 8% (w / w) phosphoric acid aqueous solution and is passivated at room temperature for 8 minutes. The rinsing is performed after passivation by rinsing with flowing deionized water for 50 seconds. The drying treatment is performed after rinsing by placing the substrate in an oven and drying it at 130°C for 35 minutes.

[0051] In step (6), the base glaze is sprayed and the wet film thickness is controlled at 0.33 mm. After standing at room temperature to level, it is dried at 105℃ for 30 min.

[0052] In step (6), the surface glaze is sprayed and the wet film thickness is controlled at 0.27 mm. After leveling at room temperature, it is dried at 105℃ for 30 min.

[0053] In step (7), the temperature is increased from room temperature to 895°C at a rate of 3°C / min.

[0054] Example 2

[0055] The corrosion-resistant enamel material described in Example 2 is composed of a Q345R low-alloy steel substrate and an enamel coating. The enamel coating consists of a base glaze layer and a top glaze layer. The base glaze layer, by weight, comprises 100 parts of glaze A, 0.35 parts of silica, and 4.0 parts of quartz powder. Glaze A, by weight, comprises the following raw materials: 62 parts of silicon dioxide, 5.5 parts of alumina, 12 parts of boron trioxide, 3.5 parts of phosphorus pentoxide, 4.0 parts of strontium borate, and 3.5 parts of lithium metaborate. The surface glaze layer, by weight, consists of 100 parts of glaze B, 3.6 parts of modified nano-sepiolite, and 3.0 parts of magnesium aluminum spinel micro powder. Glaze B, by weight, consists of the following raw materials: 65 parts of silicon dioxide, 6.5 parts of alumina, 13 parts of boron trioxide, 3.5 parts of lithium silicate, 1.4 parts of sodium bismuthate, 2.6 parts of zinc fluorosilicate, 3.2 parts of potassium hexatitanate, and 3.4 parts of lanthanum metatantalate.

[0056] The chemical composition of the Q345R low alloy steel substrate, by mass percentage, is as follows: C 0.13%, Si 0.50%, Mn 1.20%, P 0.016%, S 0.008%, Cu 0.09%, Ni 0.06%, Cr 0.08%, Mo 0.04%, with Fe as the balance.

[0057] The particle size of the magnesium aluminum spinel powder in the glaze layer is 3.0 micrometers.

[0058] The preparation method of modified nano-sepiolite in the glaze layer consists of the following steps: ① Adding nano-sepiolite to deionized water and ultrasonically dispersing it to prepare a suspension; ② Adding hydrochloric acid solution to the above suspension and stirring the mixture in a constant temperature water bath at 50℃ for 5 hours; ③ After the reaction is completed, vacuum filtering is performed to obtain a solid product, which is then washed until the pH value of the filtrate is 7.0 and no white precipitate is formed upon addition of silver nitrate solution; ④ The washed product is placed in a freeze dryer for drying; ⑤ The dried product is ground using a planetary ball mill to prepare modified nano-sepiolite.

[0059] In step ① of the preparation method of modified nano-sepiolite, the weight ratio of nano-sepiolite to deionized water is 1:12.

[0060] In step ① of the preparation method of modified nano-sepiolite, the ultrasonic dispersion power is 300W and the ultrasonic dispersion time is 30min.

[0061] In step ② of the preparation method of modified nano-sepiolite, the concentration of hydrochloric acid solution is 1.5 mol / L, and the weight ratio of hydrochloric acid solution to nano-sepiolite is 8:1.

[0062] In step ② of the preparation method of modified nano-sepiolite, the stirring speed is 300 r / min.

[0063] In step ③ of the preparation method of modified nano-sepiolite, the washing is performed by washing five times with a mixture of deionized water and anhydrous ethanol at a volume ratio of 1:1.

[0064] The drying process described in step ④ of the preparation method of modified nano-sepiolite is drying at -40℃ and 10Pa vacuum for 12 hours.

[0065] In step ⑤ of the preparation method of modified nano-sepiolite, the ball-to-material ratio during grinding is 10:1, the rotation speed is 250 r / min, and the grinding time is 30 min.

[0066] The method for preparing the corrosion-resistant enamel material described in Example 2 consists of the following steps: (1) The raw materials of glaze A are prepared according to the formula and mixed in a ball mill for 2.5 hours. The mixed powder is melted and water-quenched into glass glaze block A. Glass glaze block A is ball-milled for 2.0 hours and passed through a 200-mesh sieve to prepare glaze A. (2) Mix glaze A, white carbon black and quartz powder evenly to obtain mixed powder. Mix the mixed powder with deionized water and stir. Let it stand until the bubbles escape to form a slurry to prepare the base glaze slurry. (3) The raw materials of glaze B are prepared according to the formula and mixed in a ball mill for 2.5 hours. The mixed powder is melted and water-quenched into glass glaze block B. The glass glaze block B is ball-milled for 1.8 hours and passed through a 200-mesh sieve to prepare glaze B. (4) Mix glaze B, modified nano sepiolite and magnesium aluminum spinel powder evenly to obtain mixed powder. Mix the mixed powder with deionized water and stir. Let it stand until the bubbles escape to form a slurry to prepare the surface glaze slurry. (5) The Q345R low alloy steel substrate is subjected to alkaline immersion degreasing, pickling derusting, passivation, rinsing and drying to prepare a pretreated Q345R low alloy steel substrate. (6) Spray the base glaze evenly on the surface of the pretreated Q345R low alloy steel substrate, let it stand at room temperature for 8 minutes to level and then dry it. Spray the top glaze evenly on the dried base glaze surface, let it stand at room temperature for 8 minutes again and then dry it to obtain the coated workpiece. (7) The coated workpiece is sent into a firing kiln and kept at 890℃ for 20 minutes to prepare corrosion-resistant enamel material.

[0067] In step (1), the powder melting temperature is 1210℃ and the melting time is 45min.

[0068] In step (2), the mass ratio of the mixed powder to deionized water is 2.2:1.

[0069] In step (3), the melting temperature is 1230℃ and the melting time is 35min.

[0070] In step (4), the mass ratio of the mixed powder to deionized water is 2.4:1.

[0071] In step (5), the alkaline immersion degreasing uses a composite strong alkali degreasing solution. The chemical composition of the composite strong alkali degreasing solution is: 27g of sodium hydroxide, 38g of sodium carbonate, and 17g of trisodium phosphate per liter of aqueous solution. The Q345R low alloy steel substrate is immersed in the composite strong alkali degreasing solution at 57°C for 18 minutes. After removal, it is rinsed with flowing deionized water for 3 minutes until the pH of the rinsing solution is 7.0. The pickling rust removal uses a mixed pickling solution, which is a 6% (w / w) dilute hydrochloric acid aqueous solution. 0.4g of hexamethylenetetramine is added to each liter of the dilute hydrochloric acid aqueous solution. The substrate is immersed in the mixed pickling solution at room temperature for 10 minutes. After pickling, it is rinsed with flowing deionized water for 3 minutes until the pH of the rinsing solution is 7.0. The passivation treatment uses an 8% (w / w) phosphoric acid aqueous solution and is passivated at room temperature for 8 minutes. The rinsing is performed after passivation by rinsing with flowing deionized water for 50 seconds. The drying treatment is performed after rinsing by placing the substrate in an oven and drying it at 130°C for 35 minutes.

[0072] In step (6), the base glaze is sprayed and the wet film thickness is controlled at 0.33 mm. After standing at room temperature to level, it is dried at 100℃ for 35 min.

[0073] In step (6), the surface glaze is sprayed and the wet film thickness is controlled at 0.27 mm. After leveling at room temperature, it is dried at 100℃ for 35 min.

[0074] In step (7), the temperature is increased from room temperature to 890°C at a rate of 3°C / min.

[0075] Example 3

[0076] The corrosion-resistant enamel material described in Example 3 is composed of a Q345R low-alloy steel substrate and an enamel coating. The enamel coating consists of a base glaze layer and a top glaze layer. The base glaze layer, by weight, comprises 100 parts of glaze A, 0.4 parts of silica, and 3.0 parts of quartz powder. Glaze A, by weight, comprises the following raw materials: 64 parts of silicon dioxide, 6.0 parts of alumina, 14 parts of boron trioxide, 2.5 parts of phosphorus pentoxide, 4.5 parts of strontium borate, and 3.3 parts of lithium metaborate. The surface glaze layer, by weight, consists of 100 parts of glaze B, 3.8 parts of modified nano-sepiolite, and 2.8 parts of magnesium aluminum spinel micro powder. Glaze B, by weight, consists of the following raw materials: 67 parts of silicon dioxide, 7.0 parts of alumina, 11 parts of boron trioxide, 3.7 parts of lithium silicate, 1.2 parts of sodium bismuthate, 2.8 parts of zinc fluorosilicate, 3.0 parts of potassium hexatitanate, and 3.6 parts of lanthanum metatantalate.

[0077] The chemical composition of the Q345R low alloy steel substrate, by mass percentage, is as follows: C 0.14%, Si 0.45%, Mn 1.70%, P 0.020%, S 0.006%, Cu 0.08%, Ni 0.08%, Cr 0.06%, Mo 0.05%, with Fe as the balance.

[0078] The particle size of the magnesium aluminum spinel powder in the surface glaze layer is 2.5 micrometers.

[0079] The preparation method of modified nano-sepiolite in the glaze layer consists of the following steps: ① Adding nano-sepiolite to deionized water and ultrasonically dispersing it to prepare a suspension; ② Adding hydrochloric acid solution to the above suspension and stirring the mixture in a constant temperature water bath at 50℃ for 5 hours; ③ After the reaction is completed, vacuum filtering is performed to obtain a solid product, which is then washed until the pH value of the filtrate is 7.0 and no white precipitate is formed upon addition of silver nitrate solution; ④ The washed product is placed in a freeze dryer for drying; ⑤ The dried product is ground using a planetary ball mill to prepare modified nano-sepiolite.

[0080] In step ① of the preparation method of modified nano-sepiolite, the weight ratio of nano-sepiolite to deionized water is 1:12.

[0081] In step ① of the preparation method of modified nano-sepiolite, the ultrasonic dispersion power is 300W and the ultrasonic dispersion time is 30min.

[0082] In step ② of the preparation method of modified nano-sepiolite, the concentration of hydrochloric acid solution is 1.5 mol / L, and the weight ratio of hydrochloric acid solution to nano-sepiolite is 8:1.

[0083] In step ② of the preparation method of modified nano-sepiolite, the stirring speed is 300 r / min.

[0084] In step ③ of the preparation method of modified nano-sepiolite, the washing is performed by washing five times with a mixture of deionized water and anhydrous ethanol at a volume ratio of 1:1.

[0085] The drying process described in step ④ of the preparation method of modified nano-sepiolite is drying at -40℃ and 10Pa vacuum for 12 hours.

[0086] In step ⑤ of the preparation method of modified nano-sepiolite, the ball-to-material ratio during grinding is 10:1, the rotation speed is 250 r / min, and the grinding time is 30 min.

[0087] The method for preparing the corrosion-resistant enamel material described in Example 3 consists of the following steps: (1) Prepare the raw materials of glaze A according to the formula and mix them in a ball mill for 3 hours. Melt and quench the mixed powder to form glass glaze block A. Ball mill the glass glaze block A for 2.5 hours and pass it through a 200-mesh sieve to prepare glaze A. (2) Mix glaze A, white carbon black and quartz powder evenly to obtain mixed powder. Mix the mixed powder with deionized water and stir. Let it stand until the bubbles escape to form a slurry to prepare the base glaze slurry. (3) The raw materials of glaze B are prepared according to the formula and mixed in a ball mill for 3 hours. The mixed powder is melted and water-quenched into glass glaze block B. The glass glaze block B is ball-milled for 2.0 hours and passed through a 200-mesh sieve to prepare glaze B. (4) Mix glaze B, modified nano sepiolite and magnesium aluminum spinel powder evenly to obtain mixed powder. Mix the mixed powder with deionized water and stir. Let it stand until the bubbles escape to form a slurry to prepare the surface glaze slurry. (5) The Q345R low alloy steel substrate is subjected to alkaline immersion degreasing, pickling derusting, passivation, rinsing and drying to prepare a pretreated Q345R low alloy steel substrate. (6) Spray the base glaze evenly on the surface of the pretreated Q345R low alloy steel substrate, let it stand at room temperature for 10 minutes to level, and then dry it. Spray the top glaze evenly on the dried base glaze surface, let it stand at room temperature for 10 minutes again, and then dry it to obtain the coated workpiece. (7) The coated workpiece is sent into a firing kiln and kept at 900℃ for 18 minutes to prepare corrosion-resistant enamel material.

[0088] In step (1), the powder melting temperature is 1220℃ and the melting time is 40min.

[0089] In step (2), the mass ratio of the mixed powder to deionized water is 2.0:1.

[0090] In step (3), the melting temperature is 1240℃ and the melting time is 30min.

[0091] In step (4), the mass ratio of the mixed powder to deionized water is 2.3:1.

[0092] In step (5), the alkaline immersion degreasing uses a composite strong alkali degreasing solution. The chemical composition of the composite strong alkali degreasing solution is: 27g of sodium hydroxide, 38g of sodium carbonate, and 17g of trisodium phosphate per liter of aqueous solution. The Q345R low alloy steel substrate is immersed in the composite strong alkali degreasing solution at 57°C for 18 minutes. After removal, it is rinsed with flowing deionized water for 3 minutes until the pH of the rinsing solution is 7.0. The pickling rust removal uses a mixed pickling solution, which is a 6% (w / w) dilute hydrochloric acid aqueous solution. 0.4g of hexamethylenetetramine is added to each liter of the dilute hydrochloric acid aqueous solution. The substrate is immersed in the mixed pickling solution at room temperature for 10 minutes. After pickling, it is rinsed with flowing deionized water for 3 minutes until the pH of the rinsing solution is 7.0. The passivation treatment uses an 8% (w / w) phosphoric acid aqueous solution and is passivated at room temperature for 8 minutes. The rinsing is performed after passivation by rinsing with flowing deionized water for 50 seconds. The drying treatment is performed after rinsing by placing the substrate in an oven and drying it at 130°C for 35 minutes.

[0093] In step (6), the base glaze is sprayed and the wet film thickness is controlled at 0.33 mm. After standing at room temperature and leveling, it is dried at 110℃ for 25 min.

[0094] In step (6), the surface glaze is sprayed and the wet film thickness is controlled at 0.27 mm. After leveling at room temperature, it is dried at 110℃ for 25 min.

[0095] In step (7), the temperature is increased from room temperature to 900℃ at a heating rate of 3℃ / min.

[0096] Comparative Example 1 The preparation method of the corrosion-resistant enamel material described in Comparative Example 1 is the same as that in Example 1, except that the raw material composition is different. The difference between the corrosion-resistant enamel material described in Comparative Example 1 and Example 1 lies in the raw materials of glaze A in the base glaze layer. Glaze A, by weight, consists of the following raw materials: 63 parts silicon dioxide, 5.7 parts alumina, 13 parts boron trioxide, 3.0 parts phosphorus pentoxide, 4.3 parts strontium borate, and 3.4 parts lithium metaborate.

[0097] Comparative Example 2 The preparation method of the corrosion-resistant enamel material described in Comparative Example 2 is the same as that in Example 1, except that the raw material composition is different. The difference between the corrosion-resistant enamel material described in Comparative Example 2 and Example 1 lies in the raw materials of glaze B in the surface glaze layer. Glaze B, by weight, consists of the following raw materials: 66 parts silicon dioxide, 6.7 parts alumina, 12 parts boron trioxide, 3.6 parts lithium silicate, and 1.3 parts sodium bismuthate.

[0098] The corrosion-resistant enamel materials prepared in Examples 1-3 and Comparative Examples 1-2 were subjected to performance tests. The test method for resistance to 20% boiling hydrochloric acid for 168 hours was GB / T 7989; the test method for resistance to 0.1 mol / L sodium hydroxide at 80℃ for 24 hours was GB / T 7991.1-2021 "Test Methods for Enamel Layers Part 1: Determination of Resistance to Corrosion by Alkaline Solutions". The test results are shown in Table 1 below. Table 1. Test results of corrosion-resistant enamel materials As shown in Table 1, the enamel materials prepared in Examples 1-3 have significantly better performance than those in Comparative Examples 1-2. The corrosion resistance of the enamel materials prepared in Comparative Examples 1-2 is reduced due to the lack of an adhesive (a mixture of manganese tetroxide, bismuth vanadate, and barium molybdate) in the base glaze layer or the lack of corrosion-resistant materials (a mixture of zinc fluorosilicate, potassium hexatitanate, and lanthanum metatantalate) in the top glaze layer.

[0099] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A corrosion-resistant enamel material, characterized in that: It is composed of a Q345R low-alloy steel substrate and an enamel coating; wherein, the enamel coating consists of a base glaze layer and a top glaze layer. The base glaze layer, by weight, consists of 100 parts of glaze A, 0.35-0.4 parts of fumed silica, and 3.0-4.0 parts of quartz powder. Glaze A, by weight, consists of the following raw materials: 62-64 parts of silicon dioxide, 5.5-6.0 parts of alumina, 12-14 parts of boron trioxide, 2.5-3.5 parts of phosphorus pentoxide, 4.0-4.5 parts of strontium borate, 3.3-3.5 parts of lithium metaborate, 2.8-3.0 parts of manganese tetroxide, and vanadate. The glaze layer comprises, by weight, 1.6-1.8 parts bismuth and 2.3-2.5 parts barium molybdate; the surface glaze layer, by weight, consists of 100 parts glaze B, 3.6-3.8 parts modified nano-sepiolite, and 2.8-3.0 parts magnesium aluminum spinel micro powder. The glaze B, by weight, consists of the following raw materials: 65-67 parts silicon dioxide, 6.5-7.0 parts alumina, 11-13 parts boron trioxide, 3.5-3.7 parts lithium silicate, 1.2-1.4 parts sodium bismuthate, 2.6-2.8 parts zinc fluorosilicate, 3.0-3.2 parts potassium hexatitanate, and 3.4-3.6 parts lanthanum metatantalate.

2. The corrosion-resistant enamel material according to claim 1, characterized in that: The chemical composition of the Q345R low alloy steel substrate, by mass percentage, is as follows: C 0.12-0.14%, Si 0.45-0.50%, Mn 1.20-1.70%, P 0.016-0.020%, S 0.005-0.008%, Cu 0.07-0.09%, Ni 0.05-0.08%, Cr 0.05-0.08%, Mo 0.03-0.05%, with Fe as the balance.

3. The corrosion-resistant enamel material according to claim 1, characterized in that: The particle size of the magnesium aluminum spinel powder in the surface glaze layer is 2.5-3.0 micrometers; The preparation method of modified nano-sepiolite in the glaze layer consists of the following steps: ① Adding nano-sepiolite to deionized water and ultrasonically dispersing it to prepare a suspension; ② Adding hydrochloric acid solution to the above suspension and stirring the mixture in a constant temperature water bath at 50℃ for 5 hours; ③ After the reaction is completed, vacuum filtering is performed to obtain a solid product, which is then washed until the pH value of the filtrate is 7.0 and no white precipitate is formed upon addition of silver nitrate solution; ④ The washed product is placed in a freeze dryer for drying; ⑤ The dried product is ground using a planetary ball mill to prepare modified nano-sepiolite.

4. The corrosion-resistant enamel material according to claim 3, characterized in that: In step ① of the preparation method of modified nano-sepiolite, the weight ratio of nano-sepiolite to deionized water is 1:

12. In step ① of the preparation method of modified nano-sepiolite, the ultrasonic dispersion power is 300W and the ultrasonic dispersion time is 30min.

5. The corrosion-resistant enamel material according to claim 3, characterized in that: In step ② of the preparation method of modified nano-sepiolite, the concentration of hydrochloric acid solution is 1.5 mol / L, and the weight ratio of hydrochloric acid solution to nano-sepiolite is 8:

1. In step ② of the preparation method of modified nano-sepiolite, the stirring speed is 300 r / min.

6. The corrosion-resistant enamel material according to claim 3, characterized in that: In step ③ of the preparation method of modified nano-sepiolite, the washing is performed by washing five times with a mixture of deionized water and anhydrous ethanol at a volume ratio of 1:

1. The drying process described in step ④ of the preparation method of modified nano-sepiolite is drying at -40℃ and 10Pa vacuum for 12 hours; In step ⑤ of the preparation method of modified nano-sepiolite, the ball-to-material ratio during grinding is 10:1, the rotation speed is 250 r / min, and the grinding time is 30 min.

7. A method for preparing the corrosion-resistant enamel material according to claim 1, characterized in that: It consists of the following steps: (1) Prepare the raw materials of glaze A according to the formula and mix them in a ball mill for 2.5-3 hours. Melt and quench the mixed powder to form glass glaze block A. Ball mill the glass glaze block A for 2.0-2.5 hours and pass it through a 200-mesh sieve to prepare glaze A. (2) Mix glaze A, white carbon black and quartz powder evenly to obtain mixed powder. Mix the mixed powder with deionized water and stir. Let it stand until the bubbles escape to form a slurry to prepare the base glaze slurry. (3) Prepare the raw materials of glaze B according to the formula and mix them in a ball mill for 2.5-3 hours. Melt and quench the mixed powder to form glass glaze block B. Ball mill the glass glaze block B for 1.8-2.0 hours and pass it through a 200-mesh sieve to prepare glaze B. (4) Mix glaze B, modified nano sepiolite and magnesium aluminum spinel powder evenly to obtain mixed powder. Mix the mixed powder with deionized water and stir. Let it stand until the bubbles escape to form a slurry to prepare the surface glaze slurry. (5) The Q345R low alloy steel substrate is subjected to alkaline immersion degreasing, pickling derusting, passivation, rinsing and drying to prepare a pretreated Q345R low alloy steel substrate. (6) Spray the base glaze evenly on the surface of the pretreated Q345R low alloy steel substrate, let it stand at room temperature for 8-10 minutes to level, and then dry it. Spray the top glaze evenly on the dried base glaze surface, let it stand at room temperature for 8-10 minutes again, and then dry it to obtain the coated workpiece. (7) The coated workpiece is sent into a firing kiln and kept at 890-900℃ for 18-20 minutes to prepare corrosion-resistant enamel material.

8. The method for preparing the corrosion-resistant enamel material according to claim 7, characterized in that: In step (1), the powder melting temperature is 1210-1220℃ and the melting time is 40-45min; In step (2), the mass ratio of the mixed powder to deionized water is 2.0-2.2:1; In step (3), the melting temperature is 1230-1240℃ and the melting time is 30-35min; In step (4), the mass ratio of the mixed powder to deionized water is 2.3-2.4:

1.

9. The method for preparing the corrosion-resistant enamel material according to claim 7, characterized in that: In step (5), the alkaline immersion degreasing uses a composite strong alkali degreasing solution. The chemical composition of the composite strong alkali degreasing solution is: 27g of sodium hydroxide, 38g of sodium carbonate, and 17g of trisodium phosphate per liter of aqueous solution. The Q345R low alloy steel substrate is immersed in the composite strong alkali degreasing solution at 57°C for 18 minutes. After removal, it is rinsed with flowing deionized water for 3 minutes until the pH of the rinsing solution is 7.

0. The pickling rust removal uses a mixed pickling solution, which is a 6% (w / w) dilute hydrochloric acid aqueous solution. 0.4g of hexamethylenetetramine is added to each liter of the dilute hydrochloric acid aqueous solution. The substrate is immersed in the mixed pickling solution at room temperature for 10 minutes. After pickling, it is rinsed with flowing deionized water for 3 minutes until the pH of the rinsing solution is 7.

0. The passivation treatment uses an 8% (w / w) phosphoric acid aqueous solution and is passivated at room temperature for 8 minutes. The rinsing is performed after passivation by rinsing with flowing deionized water for 50 seconds. The drying treatment is performed after rinsing by placing the substrate in an oven and drying it at 130°C for 35 minutes.

10. The method for preparing the corrosion-resistant enamel material according to claim 7, characterized in that: In step (6), the base glaze is sprayed and the wet film thickness is controlled at 0.33 mm. After standing at room temperature and leveling, it is dried at 100-110℃ for 25-35 min. In step (6), the surface glaze slurry is sprayed, and the wet film thickness is controlled at 0.27 mm. After standing at room temperature and leveling, it is dried at 100-110℃ for 25-35 min. In step (7), the temperature is increased from room temperature to 890-900℃ at a heating rate of 3℃ / min.

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