Preparation process of a silicon crystal glaze composite layer of an inner container of a vacuum cup

Abstract

The application relates to a preparation process of a vacuum cup inner container silicon crystal glaze composite layer, which comprises the following steps: S1, performing degreasing, roughening, cleaning and drying on the surface of a stainless steel inner container to obtain a pretreated inner container; S2, coating a bottom layer glaze slurry on the surface of the pretreated inner container, baking the bottom layer glaze film to a water content of 5-15 wt%, and then coating a surface layer glaze slurry to obtain a composite glaze blank; S3, performing first stage calcination on the composite glaze blank at a temperature of 560-630 DEG C, then performing second stage calcination at a temperature of 680-730 DEG C, and then cooling to obtain the vacuum cup inner container silicon crystal glaze composite layer; the bottom layer glaze slurry contains a first borosilicate glass frit and a white feldspar composite particle component, the surface layer glaze slurry contains a second borosilicate glass frit and a white feldspar composite particle component, and the first borosilicate glass frit and the second borosilicate glass frit have a softening point difference of 20-80 DEG C. The application has the effect of improving the phenomena of easy peeling, cracking and corrosion of the inner container coating.

Description

Technical Field

[0001] This application relates to the field of coating technology for the inner liner of a thermos cup, and in particular to a process for preparing a silicon crystal glaze composite layer for the inner liner of a thermos cup. Background Technology

[0002] Stainless steel is widely used as the base material for the inner liner of thermos flasks due to its good mechanical strength, processing performance, and corrosion resistance. However, when stainless steel inner liners are in prolonged contact with hot water, tea, or beverages containing organic acids and undergo repeated washing, tea stains, limescale, and organic residues easily accumulate on their surface. This challenges the stability of the local passivation film and reduces surface cleanliness. To isolate the metal substrate and improve stain resistance, corrosion resistance, and ease of cleaning, existing technologies typically apply organic coatings or inorganic glazes to the inner liner surface.

[0003] Organic coatings are prone to aging, cracking, or interface desorption under long-term boiling water immersion and thermal cycling conditions. Although inorganic glazes have the advantages of heat resistance and chemical resistance, the thermal expansion coefficient of thin-walled stainless steel substrates is relatively high. If ordinary single-layer glazes are not designed to adapt to the thermal expansion of stainless steel substrates, residual stress can easily accumulate in the glaze during firing, cooling, and subsequent alternating use, leading to microcracks, bulging, or even localized peeling. Furthermore, when single-layer glazes are fired at lower temperatures, the process window for glass phase flow, spreading, and densification is narrow, making it difficult for pores to close completely. On the other hand, simply increasing the firing temperature or extending the holding time can easily cause changes in the microstructure and properties of the thin-walled stainless steel liner and thermal deformation.

[0004] Existing technologies include adding components such as ZrO2 and SiO2 to the glaze layer to improve its performance. However, most of these methods still employ a single-layer structure or simple multi-layer stacking, lacking a synergistic design between the underlying adhesion interface and the dense protective layer on the surface. Furthermore, they fail to adequately address the thermal expansion matching issue between the glaze layer and the stainless steel substrate, making it difficult to simultaneously achieve adhesion stability and chemical corrosion resistance. In addition, while traditional adhesion promoters containing Co and Ni oxides can improve interfacial bonding, their use in food contact products may raise concerns about metal ion migration. Summary of the Invention

[0005] To improve the problems of easy peeling, cracking, and corrosion of the inner liner coating, this application provides a process for preparing a silicon crystal glaze composite layer for the inner liner of a thermos cup.

[0006] The technical solution provided in this application for preparing a silicon crystal glaze composite layer for the inner liner of a thermos cup is as follows: A process for preparing a silicon crystal glaze composite layer for the inner liner of a thermos cup includes the following steps: S1. Degrease, roughen, clean and dry the surface of the stainless steel inner liner to obtain a pretreated inner liner; S2. Apply the bottom glaze to the surface of the pretreated inner liner and bake until the moisture content of the bottom glaze film is 5-15wt%. Then apply the surface glaze to obtain the composite glaze blank. S3. The composite glaze blank is calcined at 560-630℃ for the first stage, and then calcined at 680-730℃ for the second stage. After cooling, the silicon crystal glaze composite layer of the thermos cup liner is obtained. The bottom glaze contains a first borosilicate glass frit and leucite composite particles, and the top glaze contains a second borosilicate glass frit and leucite composite particles. The softening point of the second borosilicate glass frit is 20-80°C higher than that of the first borosilicate glass frit.

[0007] By adopting the above technical solution, the moisture content of the underlying glaze film is controlled at 5-15wt% before the surface glaze is applied. This allows the surface glaze to moderately rewet the underlying glaze film, improving interlayer contact and preventing excessive residual moisture from escaping during subsequent drying and firing. The softening point of the second borosilicate glass frit is 20-80℃ higher than that of the first borosilicate glass frit. The first stage of calcination is used to remove residual moisture and organic additives and preheat the underlying frit to near or into the softening zone. When the temperature continues to rise, the underlying layer with a lower softening point undergoes viscous flow and wets the stainless steel substrate before the surface layer. Subsequently, the surface layer softens, levels, and densifies, which helps to reduce interlayer porosity, pinholes, and bubbles, while also ensuring interfacial bonding and surface sealing.

[0008] Preferably, the leucite composite particle component is prepared by the following method: Leucite particles were mixed with water and ethanol, and tetraethyl orthosilicate was added under alkaline catalytic conditions. After polycondensation, the mixture was separated to obtain silica-coated leucite particles. The silica-coated leucite particles were then mixed with water, and zirconium oxychloride octahydrate was added to hydrolyze the zirconium oxychloride octahydrate and form a zirconium-containing deposition layer on the particle surface. After separation, washing, drying, and calcination at 450-550℃, leucite composite particles were obtained.

[0009] By adopting the above technical solution, a silicon-oxygen transition layer and a zirconium-containing oxide layer are sequentially constructed on the surface of leucite particles. The interface adjustment is brought forward to the particle preparation stage, which helps to reduce the problems of agglomeration and uneven dispersion caused by directly adding fine oxide powder to the glaze slurry. The silicon-oxygen transition layer can provide a more continuous deposition interface for zirconium salt hydrolysis products. After calcination, the zirconium-containing precursor layer forms a zirconium-containing oxide layer, thereby concentrating the zirconium-containing components on the particle surface and reducing the risk of local agglomeration defects formed by free zirconium oxide particles.

[0010] Preferably, the mass ratio of leucite to tetraethyl orthosilicate is 1:(0.18-0.26).

[0011] By adopting the above technical solution, the mass ratio between leucite and tetraethyl orthosilicate is preferably within the above range, which is beneficial to forming a silicon-oxygen transition layer of moderate thickness. This can not only mitigate the difference in interface properties between leucite and the glass phase, but also reduce the effect of leucite as a thermal expansion regulating phase due to excessive coating thickness.

[0012] Preferably, the mass ratio of the silica-coated leucite particles to zirconium oxychloride octahydrate is 1:(0.03-0.15), and the pH of the zirconium salt hydrolysis deposition is 7.0-8.0, the temperature is 50-70℃, and the time is 4-8h.

[0013] By adopting the above technical solution, it is preferable that the mass ratio between silica-coated leucite and zirconium oxychloride octahydrate is within the above range, which is conducive to the formation of a relatively continuous zirconium-containing deposition layer. At the same time, by controlling the zirconium salt hydrolysis deposition conditions within the above range, the zirconium-containing hydrolysis products can preferentially nucleate and deposit on the surface of the silicon-oxygen transition layer, reducing independent nucleation and agglomeration.

[0014] Preferably, in the preparation process of the leucite composite particle component, after adding tetraethyl orthosilicate and reacting for 0.5-2 hours, aluminum hydroxide sol is added to the reaction system and the reaction continues for 2-6 hours, so that the silicon-oxygen transition layer formed by subsequent calcination is an aluminum-containing silicon-oxygen transition layer.

[0015] By employing the above technical solution, after the reaction of tetraethyl orthosilicate, the addition of aluminum hydroxide sol allows the aluminum component to continue depositing on the surface of the initially formed silicon-oxygen network, forming an aluminum-containing silicon-oxygen transition layer after calcination. A small amount of aluminum component is beneficial for regulating the integrity, high-temperature stability, and interfacial state between the transition layer and the glass phase, thereby improving the wetting of the composite particle surface by the molten glass and reducing the interfacial stress caused by excessive shrinkage of the transition layer during subsequent firing.

[0016] Preferably, the mass ratio of the aluminum hydroxide sol to tetraethyl orthosilicate is (0.03-0.09):1.

[0017] By adopting the above technical solution, and preferably within the above-mentioned range the mass ratio between aluminum hydroxide sol and tetraethyl orthosilicate, the aluminum component is more uniformly distributed in the silicon-oxygen transition layer, which is beneficial to improving the integrity and high-temperature stability of the transition layer.

[0018] Preferably, in step S3, the temperature is increased to the first stage calcination temperature at a heating rate of 20-80℃ / min, and then increased from the first stage calcination temperature to the second stage calcination temperature at a heating rate of 30-120℃ / min.

[0019] By adopting the above technical solution, the first-stage heating rate avoids the sample being in the exhaust temperature range for a long time, while allowing necessary time for the escape of residual moisture and organic additives, reducing the risk of pinholes or blistering due to excessive heating; when the temperature rises from the first-stage calcination temperature to the second-stage calcination temperature, a higher heating rate is used, which helps to shorten the heat exposure time of the bottom layer in the softened state and reduce excessive interfacial reactions and undesirable structural changes.

[0020] Preferably, in step S3, after the second stage of firing is completed, the temperature is cooled to below 550°C at an average cooling rate of 30-50°C / min, and then cooled to below 300°C at an average cooling rate of 3-15°C / min.

[0021] By adopting the above technical solution, after the second stage of calcination, the glaze is cooled at an average cooling rate of 30-50℃ / min, which can shorten the residence time of the glaze and stainless steel substrate in the high temperature zone and reduce the risk of excessive interface reaction and thermal deformation of the inner liner. Then, the glaze is cooled to below 300℃ at an average cooling rate of 3-15℃ / min, which is conducive to the gradual release of residual thermal stress between the glaze and the stainless steel substrate, thereby reducing cooling cracking and peeling.

[0022] Preferably, the first lead-free and cadmium-free borosilicate glass frit comprises SiO2: 45-58%, B2O3: 14-24%, Al2O3: 3-8%, Li2O, Na2O, and K2O totaling 8-16%, ZnO: 3-10%, and CaO and MgO totaling 2-8%; the second lead-free and cadmium-free borosilicate glass frit comprises SiO2: 52-65%, B2O3: 10-18%, Al2O3: 4-10%, Li2O, Na2O, and K2O totaling 6-14%, ZnO: 2-8%, ZrO2: 1-5%, and CaO and MgO totaling 0-8%, with the sum of the contents of each component in each frit being 100%.

[0023] By adopting the above technical solution, the first borosilicate glass melt has a low softening point and good matrix wetting ability, which makes the second borosilicate glass melt have high network stability; B2O3 and alkali metal oxides can play a fluxing role, SiO2 and Al2O3 are conducive to building a stable glass network, and ZrO2 in the second melt is conducive to improving the wear resistance and chemical stability of the surface layer, so that the bottom layer adhesion function and the surface layer protection function complement each other.

[0024] Preferably, the solid components of the bottom glaze slurry include 100 parts of a first lead-free and cadmium-free borosilicate glass frit and 5-15 parts of leucite composite particles; the solid components of the surface glaze slurry include 100 parts of a second lead-free and cadmium-free borosilicate glass frit, 1-6 parts of SiO2, 1-6 parts of ZrO2, and 1-4 parts of leucite composite particles.

[0025] In summary, this application includes at least one of the following beneficial technical effects: The bottom layer undergoes viscous flow and wets the stainless steel substrate before the surface layer, and the surface layer subsequently levels and densifies. This can take into account the low-temperature rapid firing, interface adhesion and surface sealing of thin-walled stainless steel inner liner, and reduce the risk of interlayer cavities, pinholes and blistering. The inorganic composite particles consisting of leucite core material, silicon-oxygen transition layer and zirconium oxide layer can achieve thermal expansion regulation, inorganic interface buffering and controlled dispersion of zirconium-containing components; the introduction of aluminum components into silicon-oxygen transition layer is also beneficial to improve the integrity and high temperature stability of transition layer, thereby reducing the risk of hard particle agglomeration and interface defects forming crack initiation. The highly stable borosilicate glass network in the surface layer, along with the controlled addition of SiO2 and ZrO2, helps to improve the density and chemical stability of the glaze layer, and prolongs the diffusion path of media such as water, salt, and organic acids to the metal matrix. The resulting smooth and dense inorganic surface can also reduce the anchoring of tea stains, scale, and organic matter in pores and rough defects, which helps to improve stain resistance and easy cleaning performance. Detailed Implementation

[0026] The present application will be further described in detail below with reference to the embodiments: Raw material description: All raw materials used in the examples are commercially available; Example 1

[0027] Preparation of leucite composite particles: 100g of leucite particles, 500g of anhydrous ethanol, and 125g of deionized water were mixed and stirred at 600rpm and ultrasonically dispersed for 20min. The pH was adjusted to 10.0 with 25wt% ammonia to obtain a leucite dispersion. 18g of tetraethyl orthosilicate was diluted with 36g of anhydrous ethanol and then added dropwise to the leucite dispersion over 30min. The mixture was stirred at 25℃ for 0.5h, and then 0.54g of aluminum hydroxide sol with a solid content of 20wt% was added. The mixture was stirred for another 2h, filtered, and then washed three times alternately with anhydrous ethanol and deionized water. The mixture was dried at 80℃ for 12h to obtain aluminum-containing silicon oxide. Leucite particles were coated. 3g of zirconium oxychloride octahydrate was mixed with 100g of deionized water to obtain a zirconium oxychloride solution. 100g of the prepared aluminum silicate coated leucite particles were weighed, dispersed in 1000g of deionized water and sonicated for 20min. The pH was adjusted to 7.0 using Tris-HCl buffer, and then heated to 50℃. The zirconium oxychloride solution was added and stirred for 4h. The mixture was filtered and washed repeatedly with deionized water. It was dried at 80℃ for 12h, heated to 450℃ at a rate of 3℃ / min and held for 2h. Finally, it was naturally cooled to room temperature, ground, and passed through a 200-mesh sieve to obtain leucite composite particles.

[0028] First borosilicate glass frit: The oxides are expressed as follows by mass percentage: SiO2: 52%, B2O3: 19%, Al2O3: 5%, Li2O: 2%, Na2O: 8%, K2O: 3% (total alkali metal oxides 13%), ZnO: 6%, CaO: 3%, MgO: 2%; the softening point is 615℃ as determined by a glass softening point tester.

[0029] Second borosilicate glass frit: The oxides are expressed as follows by mass percentage: SiO2: 58%, B2O3: 14%, Al2O3: 6%, Na2O: 6%, K2O: 2% (8% total of alkali metal oxides), ZnO: 4%, ZrO2: 3%, CaO: 4%, MgO: 3%; its softening point is 670℃.

[0030] Preparation of the base glaze slurry: 100g of first borosilicate glass frit powder was mixed with 5g of leucite composite particles, then 37g of deionized water was added, along with 0.25wt% sodium carboxymethyl cellulose and 0.1wt% sodium polyacrylate relative to the solid components. The mixture was wet-milled with zirconia balls for 4 hours, passed through a 200-mesh sieve, and the pH was adjusted to 8.5 with 10wt% ammonia water to obtain the bottom glaze slurry.

[0031] Preparation of surface glaze slurry: Mix 100g of second borosilicate glass frit powder, 1g of silica, 1g of zirconium oxide and 1g of leucite composite particles, then add 34g of deionized water, and add sodium carboxymethyl cellulose (0.25wt%) and sodium polyacrylate (0.1wt%) relative to the solid components. Wet ball mill using zirconium oxide balls for 3 hours, pass through a 200-mesh sieve, and adjust the pH to 8.5 using 10wt% ammonia water to obtain the surface glaze slurry.

[0032] Preparation of the silicon crystal glaze composite layer for the inner liner of the thermos: S1. Degrease the stainless steel inner liner in a 3wt% alkaline degreasing solution at 55℃ for 8 minutes. After rinsing with deionized water, roughen the inner surface by sandblasting with 180-mesh alumina sand at 0.25MPa for 20 seconds. Then, ultrasonically clean with deionized water for 5 minutes and dry at 100℃ for 10 minutes to obtain the pretreated inner liner. S2. Apply the bottom layer glaze by internal wall spraying, control the dry film thickness of the bottom layer to 40μm, and then dry it at 80℃ until the moisture content of the bottom layer glaze film is 5wt%. Spray the surface glaze, control the dry film thickness of the surface layer to 25μm, and dry it at 80℃ for 5min to obtain the composite glaze blank. S3. Place the composite glaze blank in an electric furnace, heat it to 560℃ at 20℃ / min and hold it for 6min to complete the first stage of calcination, then heat it to 680℃ at 30℃ / min and hold it for 2min to complete the second stage of calcination, then cool it to 540℃ at 30℃ / min, then cool it to 290℃ at 3℃ / min, and finally let it cool naturally to room temperature to obtain the silicon crystal glaze composite layer of the thermos cup inner liner. Example 2

[0033] Preparation of leucite composite particles: 100g of leucite particles, 500g of anhydrous ethanol, and 125g of deionized water were mixed and ultrasonically dispersed at 700rpm for 20min. The pH was adjusted to 10.5 with 25wt% ammonia to obtain a leucite dispersion. 26g of tetraethyl orthosilicate was diluted with 52g of anhydrous ethanol and then added dropwise to the leucite dispersion over 45min. The mixture was stirred at 25℃ for 2h, and then 2.34g of aluminum hydroxide sol with a solid content of 20wt% was added. The mixture was stirred for another 6h, filtered, and washed three times alternately with anhydrous ethanol and deionized water. The mixture was then dried at 90℃ for 12h to obtain an aluminum-containing... Silica-coated leucite particles: 15g of zirconium oxychloride octahydrate was mixed with 150g of deionized water to obtain a zirconium oxychloride solution; 100g of aluminum-containing silica-coated leucite particles were weighed, dispersed in 1000g of deionized water and sonicated for 20min, the pH was adjusted to 8.0 using Tris-HCl buffer, then the temperature was raised to 70℃, the zirconium oxychloride solution was added and stirring was continued for 8h, the mixture was filtered and repeatedly washed with deionized water, dried at 90℃ for 12h, the temperature was raised to 550℃ at 3℃ / min and held for 2h, and finally cooled naturally to room temperature, ground and passed through a 200-mesh sieve to obtain leucite composite particles.

[0034] First borosilicate glass frit: The oxides are expressed as follows by mass percentage: SiO2: 52%, B2O3: 14%, Al2O3: 8%, Na2O: 4%, K2O: 4% (8% total alkali metal oxides), ZnO: 10%, MgO: 8%; the softening point is 615℃ as determined by a glass softening point tester.

[0035] Second borosilicate glass frit: The oxides are expressed as follows by mass percentage: SiO2: 61%, B2O3: 10%, Al2O3: 10%, Na2O: 3%, K2O: 3% (6% total of alkali metal oxides), ZnO: 8%, ZrO2: 5%, and its softening point is 670℃.

[0036] Preparation of the base glaze slurry: 100g of first borosilicate glass frit powder was mixed with 10g of leucite composite particles, then 40g of deionized water was added, along with sodium carboxymethyl cellulose (0.25wt%) and sodium polyacrylate (0.1wt%) relative to the solid components. The mixture was wet-milled with zirconia balls for 4 hours, passed through a 200-mesh sieve, and the pH was adjusted to 8.5 with 10wt% ammonia water to obtain the bottom glaze slurry.

[0037] Preparation of surface glaze slurry: Mix 100g of second borosilicate glass frit powder, 6g of silica, 6g of zirconium oxide and 4g of leucite composite particles, then add 40g of deionized water, and add sodium carboxymethyl cellulose (0.25wt%) and sodium polyacrylate (0.1wt%) relative to the solid components. Wet ball mill the mixture using zirconium oxide balls for 3 hours, pass it through a 200-mesh sieve, and adjust the pH to 8.5 using 10wt% ammonia water to obtain the surface glaze slurry.

[0038] Preparation of the silicon crystal glaze composite layer for the inner liner of the thermos: S1. Degrease the stainless steel inner liner in a 3wt% alkaline degreasing solution at 55℃ for 8 minutes. After rinsing with deionized water, roughen the inner surface by sandblasting with 180-mesh alumina sand at 0.25MPa for 20 seconds. Then, ultrasonically clean with deionized water for 5 minutes and dry at 100℃ for 10 minutes to obtain the pretreated inner liner. S2. Apply the bottom layer glaze by internal wall spraying, control the dry film thickness of the bottom layer to 60μm, and then dry it at 105℃ until the moisture content of the bottom layer glaze film is 15wt%. Then spray the surface glaze, control the dry film thickness of the surface layer to 40μm, and dry it at 70℃ for 8min to obtain the composite glaze blank. S3. Place the composite glaze blank in an electric furnace, heat it to 630℃ at a rate of 80℃ / min and hold it for 3 minutes to complete the first stage of calcination, then heat it to 730℃ at a rate of 120℃ / min and hold it for 1.5 minutes to complete the second stage of calcination, then cool it to 540℃ at a rate of 50℃ / min, then cool it to 290℃ at a rate of 15℃ / min, and finally let it cool naturally to room temperature to obtain the silicon crystal glaze composite layer of the thermos cup liner. Example 3

[0039] Preparation of leucite composite particles: 100g of leucite particles, 500g of anhydrous ethanol, and 125g of deionized water were mixed and stirred at 600rpm and ultrasonically dispersed for 20min. The pH was adjusted to 10.0 with 25wt% ammonia to obtain a leucite dispersion. 22g of tetraethyl orthosilicate was diluted with 44g of anhydrous ethanol and then added dropwise to the leucite dispersion over 40min. The mixture was stirred at 25℃ for 0.5h, and then 1.32g of aluminum hydroxide sol with a solid content of 20wt% was added. The mixture was stirred for another 4h, filtered, and washed three times alternately with anhydrous ethanol and deionized water. The mixture was then dried at 85℃ for 12h to obtain the desired product. Aluminum-silica-coated leucite particles were prepared by mixing 9g of zirconium oxychloride octahydrate with 120g of deionized water to obtain a zirconium oxychloride solution; 100g of aluminum-silica-coated leucite particles were weighed, dispersed in 1000g of deionized water and sonicated for 20min, the pH was adjusted to 7.5 using Tris-HCl buffer, the temperature was raised to 60℃, the zirconium oxychloride solution was added and stirring was continued for 6h, the mixture was filtered and repeatedly washed with deionized water, dried at 85℃ for 12h, the temperature was raised to 500℃ at 3℃ / min and held for 2h, and finally cooled naturally to room temperature, ground and passed through a 200-mesh sieve to obtain leucite composite particles.

[0040] First borosilicate glass frit: The oxides are expressed as follows by mass percentage: SiO2: 52%, B2O3: 19%, Al2O3: 5.5%, Li2O: 4%, Na2O: 5%, K2O: 3% (total alkali metal oxides 12%), ZnO: 6.5%, CaO: 3%, MgO: 2%; the softening point was determined to be 615℃ using a glass softening point tester.

[0041] Second borosilicate glass frit: The oxides are expressed as follows by mass percentage: SiO2: 60%, B2O3: 14%, Al2O3: 7%, Li2O: 3.5%, Na2O: 4%, K2O: 2.5% (10% total alkali metal oxides), ZnO: 5.5%, ZrO2: 3.5%; its softening point is 670℃.

[0042] Preparation of the base glaze slurry: 100g of first borosilicate glass frit powder was mixed with 10g of leucite composite particles, then 40g of deionized water was added, along with sodium carboxymethyl cellulose (0.25wt%) and sodium polyacrylate (0.1wt%) relative to the solid components. The mixture was wet-milled with zirconia balls for 4 hours, passed through a 200-mesh sieve, and the pH was adjusted to 8.5 with 10wt% ammonia water to obtain the bottom glaze slurry.

[0043] Preparation of surface glaze slurry: Mix 100g of second borosilicate glass frit powder, 4g of silica, 4g of zirconium oxide and 3g of leucite composite particles, then add 38g of deionized water, and add sodium carboxymethyl cellulose (0.25wt%) and sodium polyacrylate (0.1wt%) relative to the solid components. Wet ball mill the mixture using zirconium oxide balls for 3 hours, pass it through a 200-mesh sieve, and adjust the pH to 8.5 using 10wt% ammonia water to obtain the surface glaze slurry.

[0044] Preparation of the silicon crystal glaze composite layer for the inner liner of the thermos: S1. Degrease the stainless steel inner liner in a 3wt% alkaline degreasing solution at 55℃ for 8 minutes. After rinsing with deionized water, roughen the inner surface by sandblasting with 180-mesh alumina sand at 0.25MPa for 20 seconds. Then, ultrasonically clean with deionized water for 5 minutes and dry at 100℃ for 10 minutes to obtain the pretreated inner liner. S2. Apply the bottom layer glaze by internal wall spraying, control the dry film thickness of the bottom layer to 50μm, and then dry it at 105℃ until the moisture content of the bottom layer glaze film is 10wt%. Then spray the surface glaze, control the dry film thickness of the surface layer to 30μm, and dry it at 75℃ for 6min to obtain the composite glaze blank. S3. Place the composite glaze blank in an electric furnace, heat it to 595℃ at a rate of 50℃ / min and hold it for 5min to complete the first stage of calcination, then heat it to 705℃ at a rate of 75℃ / min and hold it for 2min to complete the second stage of calcination, then cool it to 540℃ at a rate of 40℃ / min, then cool it to 290℃ at a rate of 8℃ / min, and finally let it cool naturally to room temperature to obtain the silicon crystal glaze composite layer of the thermos cup inner liner. Example 4

[0045] Example 4 is based on Example 3. The difference between Example 4 and Example 3 is that aluminum hydroxide sol was not added when preparing the leucite composite particles in Example 4. Example 5

[0046] Example 5 is based on Example 3. The difference between Example 5 and Example 3 is that in Example 5, when preparing leucite composite particles, zirconium oxychloride octahydrate deposition was not performed, and the aluminum-silicon-oxygen-coated leucite particles were directly calcined. Example 6

[0047] Example 6 is based on Example 3. The difference between Example 6 and Example 3 is that in Example 6, when preparing leucite composite particles, tetraethyl orthosilicate and aluminum hydroxide sol were not added. Instead, the leucite particles were directly dispersed in water and then deposited with zirconium oxychloride octahydrate. Example 7

[0048] Example 7 is based on Example 3. The difference between Example 7 and Example 3 is that in Example 7, the in-situ coating method is not used to prepare leucite composite particles. Instead, leucite, silica, alumina and zirconium oxide are physically mixed in a mass ratio of 100:6.35:0.17:3.44 to obtain physically mixed particle components. Example 8

[0049] Example 8 is based on Example 3. The difference between Example 8 and Example 3 is that the mass ratio between leucite and tetraethyl orthosilicate in Example 8 is 1:0.1. Example 9

[0050] Example 9 is based on Example 3. The difference between Example 9 and Example 3 is that the mass ratio between leucite and tetraethyl orthosilicate in Example 9 is 1:0.35. Example 10

[0051] Example 10 is based on Example 3. The difference between Example 10 and Example 3 is that the mass ratio of aluminum silicate coated leucite particles to zirconium oxychloride octahydrate in Example 10 is 1:0.01. Example 11

[0052] Example 11 is based on Example 3. The difference between Example 11 and Example 3 is that the mass ratio of aluminum silicate coated leucite particles to zirconium oxychloride octahydrate in Example 11 is 1:0.2. Example 12

[0053] Example 12 is based on Example 3. The difference between Example 12 and Example 3 is that the mass ratio of aluminum hydroxide sol to tetraethyl orthosilicate in Example 12 is 0.01:1. Example 13

[0054] Example 13 is based on Example 3. The difference between Example 13 and Example 3 is that the mass ratio between aluminum hydroxide sol and tetraethyl orthosilicate in Example 13 is 0.12:1. Example 14

[0055] Example 14 is based on Example 3. The difference between Example 14 and Example 3 is that in Example 14, the leucite composite particles in the bottom glaze and the top glaze are replaced with ordinary leucite particles. Example 15

[0056] Example 15 is based on Example 3. The difference between Example 15 and Example 3 is that in Example 15, the second borosilicate glass frit in the surface glaze is replaced with an equal amount of the first borosilicate glass frit. Example 16

[0057] Example 16 is based on Example 3. The difference between Example 16 and Example 3 is that in Example 16, the second borosilicate glass melt, by the mass percentage of oxides, is: SiO2: 65%, B2O3: 10%, Al2O3: 8%, Na2O: 3%, K2O: 2%, ZnO: 2%, ZrO2: 5%, CaO: 3%, MgO: 2%, with a softening point of 720℃. The difference in softening point between the second and first borosilicate glass melts is 105℃. Example 17

[0058] Example 17 is based on Example 3. The difference between Example 17 and Example 3 is that in Example 17, the second borosilicate glass melt, by the mass percentage of oxides, is: SiO2: 54%, B2O3: 17%, Al2O3: 5%, Li2O: 1%, Na2O: 6%, K2O: 2%, ZnO: 4%, ZrO2: 2%, CaO: 5%, MgO: 4%, with a softening point of 625℃, which is 10℃ different from the softening point of the first borosilicate glass melt.

[0059] Comparative Example 1 Comparative Example 1 is based on Example 3. In Comparative Example 1, the water content of the bottom glaze film in step S2 is 1.5 wt%.

[0060] Comparative Example 2 Comparative Example 2 is based on Example 3. In Comparative Example 2, the water content of the bottom glaze film in step S2 is 20 wt%.

[0061] Comparative Example 3 Comparative Example 3 is based on Example 3. In Comparative Example 3, neither the bottom glaze nor the top glaze contained leucite composite particles.

[0062] Comparative Example 4 Comparative Example 4 is based on Example 3, except that only the base glaze is sprayed in Comparative Example 4.

[0063] Comparative Example 5 Comparative Example 5 is based on Example 3, except that only the surface glaze is sprayed in Comparative Example 5.

[0064] Performance testing The following performance tests were performed on the samples of Examples 1-17 and Comparative Examples 1-5: (1) Adhesion Using GB / T 13484-2011 and GB / T 38168-2019 as testing references, five samples were taken for each example or comparative example. The morphology of the ceramic layer falling off in the impact area of ​​the sample was observed and judged according to filamentous, mesh, blocky and smooth. The worst grade among the five samples was taken as the adhesion result of the group. (2) Temperature difference in thermal shock crack formation Using GB / T 46603-2025 as the test reference, the thermal shock conditions were gradually increased according to the standard. The crack formation temperature at which cracks or spalling first appeared in each sample was recorded. Each sample was tested 3 times, and the average value was taken. The test results were filled in Table 1. (3) Acid resistance Using GB / T 9989.1-2015 as the testing reference, the acid resistance of the samples was tested. Each sample was tested three times, and the worst grade among the three tests was recorded as the acid resistance grade of the sample. The test results were filled in Table 1. (4) Alkali resistance weight loss test Using GB / T 9988-2025 as the testing reference, the mass loss per unit area was calculated, and the arithmetic mean was taken as the alkali resistance weight loss result. Each sample was tested three times, and the average value was taken. The test results were filled in Table 1.

[0065] Table 1 Performance test results of Examples 1-17 and Comparative Examples 1-5

[0066] As shown in Table 1, the adhesion of Examples 1-3 all reached the filamentous stage, the thermal shock crack initiation temperature difference was 260-272℃, the acid resistance grade reached A+ to AA, and the alkali resistance weight loss was 0.36-0.49 mg·cm³. -2 This indicates that, under the combined effects of leucite composite particles, a double-layer borosilicate glass system with a softening point difference, interlayer moisture content control, and staged firing, the resulting silicon crystal glaze composite layer can achieve a balance between bonding stability with the stainless steel substrate, thermal shock stability, and chemical durability.

[0067] In Example 4, no aluminum hydroxide sol was added during the preparation of leucite composite particles, and only a silica transition layer was formed. The Al component was lacking in its ability to regulate the high-temperature stability and interfacial continuity of the silicon-oxygen network.

[0068] In Example 5, no zirconium salt deposition was performed. Although the leucite composite particles still had an aluminum-silicon-oxygen transition layer, their surface corrosion resistance and high-temperature stability were reduced.

[0069] Example 6 lacks tetraethyl orthosilicate and aluminum hydroxide sol, the leucite surface lacks a silicon-oxygen transition layer, zirconium hydrolysis products are prone to uneven deposition, and interface defects and stress concentrations increase.

[0070] In Example 7, the components in the leucite composite particles were only physically mixed and did not form a core-transition layer-outer layer structure. The inorganic components agglomerated in the system, resulting in decreased stability.

[0071] In Examples 8-9, the mass ratio between leucite and tetraethyl orthosilicate is not within the range specified in this application. When tetraethyl orthosilicate is insufficient, the amount of silica generated is insufficient, making it difficult to cover the leucite. The subsequent Al and Zr deposition stability decreases, and the interface transition layer is incomplete. When tetraethyl orthosilicate is excessive, the coating layer is too thick, the melt wetting decreases, and it is easy to agglomerate.

[0072] In Examples 10-11, the mass ratio between silica-coated leucite and zirconium oxychloride octahydrate is not within the range specified in this application. When zirconium oxychloride octahydrate is insufficient, the amount of Zr hydrolysis deposition is insufficient, and the continuity of the outer layer decreases. When zirconium oxychloride octahydrate is excessive, the local thickness is too large, the viscosity is too high, and it hinders the flow of the glass phase and the closure of pores.

[0073] In Examples 12-13, the mass ratio between aluminum hydroxide sol and tetraethyl orthosilicate was not within the range specified in this application. When the aluminum hydroxide sol was insufficient, the stability of the silicon oxide layer network and the interface regulation performance decreased. When the aluminum hydroxide sol was excessive, Al enrichment increased the melt viscosity, the interface diffusion decreased, and the coating layer became uneven.

[0074] In Example 14, the leucite composite particles in both the bottom and top glaze slurries were replaced with ordinary leucite particles. Ordinary leucite can still participate in thermal expansion regulation, but it lacks an aluminum-silicon-oxygen transition layer and a zirconium oxide outer layer. Micropores are formed between the particles and the glass phase interface, and the particles debond, forming corrosion channels.

[0075] In Example 15, both the bottom and top glazes used the first borosilicate glass frit. There was no frit difference between the top and bottom layers. The top layer softened prematurely, the venting window narrowed, and the chemical stability decreased.

[0076] In Examples 16 and 17, the difference in softening point between the first borosilicate glass melt and the second borosilicate glass melt is not within the range defined in this application. When the difference in softening point is too large, the surface layer is difficult to level and close the pores, and residual particles and pores lead to stress concentration and the entry of corrosive media. When the difference in softening point is too small, the surface layer softens significantly before the bottom layer is wetted and vented, and the mixing stability between the two layers decreases.

[0077] The moisture content of the bottom glaze film in Comparative Example 1 and Comparative Example 2 is not within the range specified in this application. When the moisture content of the bottom glaze film is insufficient, the rewetting of the bottom layer by the surface glaze slurry and the interfacial contact are weakened, and the bonding between the layers of the body is insufficient. When the moisture content of the bottom glaze film is excessive, the surface spraying causes interfacial mixing of the bottom layer. During drying shrinkage, the steam discharge increases pinholes and interfacial voids, resulting in decreased stability.

[0078] In Comparative Example 3, no leucite composite particles were added to either the bottom or top glaze slurry. The system's ability to regulate the coefficient of thermal expansion and the stress involved was significantly reduced, and the surface chemical stability decreased.

[0079] Comparative Example 4 only sprayed the bottom layer of glaze, lacking the high SiO2 and ZrO2 protective layer on the surface, resulting in a relative decrease in chemical stability and wear resistance.

[0080] Comparative Example 5 only sprayed a surface glaze. Although the surface layer has high chemical stability and acid and alkali resistance, it cannot achieve sufficient wetting and interfacial bonding to the stainless steel substrate due to the lack of a base layer.

[0081] This specific embodiment is merely an explanation of this application and is not intended to limit it. Based on the above description, those skilled in the art can make various changes and modifications without departing from the technical concept of this application. The technical scope of this application is not limited to the contents of the specification but must be determined according to the scope of the claims.

Claims

1. A process for preparing a silicon crystal glaze composite layer for the inner liner of a thermos cup, characterized in that: Includes the following steps: S1. Degrease, roughen, clean and dry the surface of the stainless steel inner liner to obtain a pretreated inner liner; S2. Apply the bottom glaze to the surface of the pretreated inner liner and bake until the moisture content of the bottom glaze film is 5-15wt%. Then apply the surface glaze to obtain the composite glaze blank. S3. The composite glaze blank is calcined at 560-630℃ for the first stage, and then calcined at 680-730℃ for the second stage. After cooling, the silicon crystal glaze composite layer of the thermos cup liner is obtained. The bottom glaze contains a first borosilicate glass frit and leucite composite particles, and the top glaze contains a second borosilicate glass frit and leucite composite particles. The softening point of the second borosilicate glass frit is 20-80°C higher than that of the first borosilicate glass frit.

2. The process for preparing a silicon crystal glaze composite layer for the inner liner of a thermos cup according to claim 1, characterized in that: The leucite composite particle component was prepared by the following method: Leucite particles were mixed with water and ethanol, and tetraethyl orthosilicate was added under alkaline catalytic conditions. After polycondensation, the mixture was separated to obtain silica-coated leucite particles. The silica-coated leucite particles were then mixed with water, and zirconium oxychloride octahydrate was added to hydrolyze the zirconium oxychloride octahydrate and form a zirconium-containing deposition layer on the particle surface. After separation, washing, drying, and calcination at 450-550℃, leucite composite particles were obtained.

3. The process for preparing a silicon crystal glaze composite layer for the inner liner of a thermos cup according to claim 2, characterized in that: The mass ratio between leucite and tetraethyl orthosilicate is 1:(0.18-0.26).

4. The process for preparing a silicon crystal glaze composite layer for the inner liner of a thermos cup according to claim 2, characterized in that: The mass ratio of the silica-coated leucite particles to zirconium oxychloride octahydrate is 1:(0.03-0.15), and the zirconium salt hydrolysis deposition is carried out at a pH of 7.0-8.0, a temperature of 50-70℃, and a time of 4-8h.

5. The process for preparing a silicon crystal glaze composite layer for the inner liner of a thermos cup according to claim 2, characterized in that: In the preparation of the leucite composite particle component, after adding tetraethyl orthosilicate and reacting for 0.5-2 hours, aluminum hydroxide sol is added to the reaction system and the reaction continues for 2-6 hours, so that the silicon-oxygen transition layer formed by subsequent calcination is an aluminum-containing silicon-oxygen transition layer.

6. The process for preparing a silicon crystal glaze composite layer for the inner liner of a thermos cup according to claim 5, characterized in that: The mass ratio of the aluminum hydroxide sol to tetraethyl orthosilicate is (0.03-0.09):

1.

7. The process for preparing a silicon crystal glaze composite layer for the inner liner of a thermos cup according to claim 1, characterized in that: In step S3, the temperature is increased to the first stage calcination temperature at a heating rate of 20-80℃ / min, and then increased from the first stage calcination temperature to the second stage calcination temperature at a heating rate of 30-120℃ / min.

8. The process for preparing a silicon crystal glaze composite layer for the inner liner of a thermos cup according to claim 7, characterized in that: In step S3, after the second stage of firing is completed, the temperature is cooled to below 550°C at an average cooling rate of 30-50°C / min, and then cooled to below 300°C at an average cooling rate of 3-15°C / min.

9. The process for preparing a silicon crystal glaze composite layer for the inner liner of a thermos cup according to claim 1, characterized in that: The first lead-free and cadmium-free borosilicate glass frit comprises SiO2: 45-58%, B2O3: 14-24%, Al2O3: 3-8%, Li2O, Na2O and K2O total 8-16%, ZnO: 3-10%, and CaO and MgO total 2-8%; the second lead-free and cadmium-free borosilicate glass frit comprises SiO2: 52-65%, B2O3: 10-18%, Al2O3: 4-10%, Li2O, Na2O and K2O total 6-14%, ZnO: 2-8%, ZrO2: 1-5%, and CaO and MgO total 0-8%, and the sum of the contents of each component in each frit is 100%.

10. The process for preparing a silicon crystal glaze composite layer for the inner liner of a thermos cup according to claim 9, characterized in that: The solid components of the bottom glaze slurry include 100 parts of a first lead-free and cadmium-free borosilicate glass frit and 5-15 parts of leucite composite particles; the solid components of the surface glaze slurry include 100 parts of a second lead-free and cadmium-free borosilicate glass frit, 1-6 parts of SiO2, 1-6 parts of ZrO2 and 1-4 parts of leucite composite particles.

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