Ceramic crack repair glaze and glaze repair process

Abstract

The present invention relates to the field of ceramic repair technology, specifically a ceramic crack repair glaze and a glazing repair process. The present invention overcomes the problems of the existing ceramic repair technology that is prone to secondary cracking and poor appearance consistency after repair. First, the cracked semi-finished body is polished, and then a combined coupling agent is applied. After drying, the repair glaze A is sprayed for bisque firing, and then the repair glaze B is sprayed to cover the cracks, and finally fired to obtain a finished ceramic. By limiting the polishing time and the angle between the polishing path and the crack, changing the ratio and thickness of the combined coupling agent primer, regulating the firing temperature, the holding time and the cooling rate, and adding modified mullite to the repair glaze, the risk of cracking is reduced; changing the amount of phosphate quartz, white garnet, wollastonite and modified mullite added to the repair glaze A to reduce the glaze layer from falling off and cracking; changing the amount of polyvinyl alcohol, medium-temperature frit, tin oxide and titanium oxide added to the repair B glaze to increase the glaze viscosity, reduce the risk of cracking, correct color difference and improve appearance consistency.

Description

Technical Field

[0001] The present invention relates to the technical field of ceramic repair, in particular to a ceramic crack repair glaze and a glazing repair process. Background Art

[0002] During the manufacturing process of sanitary ceramics, unexpected situations such as cracking and falling off may sometimes occur, requiring repair. Glaze repair is a technology for repairing damage to the surface of porcelain, but the existing repair methods have shortcomings such as insufficient adhesion between the repair glaze and the porcelain itself and insufficient mechanical strength of the repair glaze after firing, resulting in a mismatch between the hardness of the repaired area and the hardness of the porcelain itself, and the repair glaze is prone to falling off and secondary cracking. The repair technology requires that it cannot fall off and crack, and it requires that it cannot shrink after firing to ensure that the cracks can be completely flat and smooth after firing, without gaps, and have a smooth transition with the surrounding interface without color difference, so that the cracks in the ceramic products can be repaired perfectly. In the existing technology, the height of the repair position of the repair glaze is often 0.1-0.25mm higher than the original glaze surface, and the repaired glaze surface is prone to crystallization, resulting in poor glaze repair effect. In summary, the existing ceramic glaze repair technology has the disadvantages of the risk of secondary cracking after repair and the inconsistency between the appearance of the repaired area and the surrounding interface.

[0003] Therefore, a ceramic crack repair glaze and a glazing repair process are proposed. Summary of the Invention

[0004] The purpose of the present invention is to provide a ceramic crack repair glaze and a glaze repair process. The present invention overcomes the problems of easy secondary cracking and poor appearance consistency after repair in existing ceramic repair technologies. The semi-finished body with cracks is first polished, and then a combined coupling agent is applied. After drying, the repair glaze A is sprayed for bisque firing, and then the repair glaze B is sprayed to cover the cracks, and finally fired to obtain a finished ceramic. By limiting the polishing time and the angle between the polishing path and the crack, changing the ratio and thickness of the combined coupling agent primer, regulating the firing temperature, the holding time and the cooling rate, and adding modified mullite to the repair glaze, the risk of cracking is reduced; the amount of phosphate quartz, white garnet, wollastonite and modified mullite added to the repair glaze A is changed to reduce the glaze layer from falling off and cracking; the amount of polyvinyl alcohol, medium-temperature frit, tin oxide and titanium oxide added to the repair B glaze is changed to increase the glaze viscosity, reduce the risk of cracking, correct color difference and improve appearance consistency.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] A ceramic crack glazing repair process comprises the following steps:

[0007] S1 Use a soft brush to remove dust and debris from the cracks on the surface of the semi-finished ceramic body; First grinding: Use medium-grained sandpaper to grind the cracks along the direction of the cracks to remove protruding debris and make the interfaces on both sides of the cracks smooth, then use a brush to remove the dust generated by grinding and wipe it clean with a damp cloth; Second grinding: Use fine sandpaper to further grind and smooth along the direction of the cracks to make the repaired area flush with the surrounding surface; Third grinding: Use ultra-fine sandpaper to grind along the direction of the cracks, wipe it clean with a soft brush and a damp cloth, and let it dry naturally to obtain a clean semi-finished ceramic body;

[0008] S2: spray a 0.1-0.8mm thick combined coupling agent primer on the cracks of the cleaned semi-finished ceramic body, and after it dries, apply repair glaze A on the cracks with a soft brush. After drying, polish with fine sandpaper until it is flush with the surrounding body, and remove dust to obtain a pre-treated semi-finished ceramic body;

[0009] S3 puts the pretreated semi-finished ceramic body into the kiln for firing. The first stage is bisque firing, heating the body to 280°C at 2°C / min and holding it for 60 minutes, then heating it to 800°C and firing it for 8 hours, then cooling it to room temperature at 2°C / min, spraying the repair B glaze evenly on its surface, and obtaining a bisque fired semi-finished body after drying; the second stage: heating the bisque fired semi-finished body to 180°C at 2°C / min and holding it for 60 minutes, then heating it to the firing temperature of 1180-1260°C at 3°C / min, and holding it for 60-240 minutes; the third stage: cooling it to room temperature at 1-3.5°C / min to obtain the finished ceramic.

[0010] Preferably, the grinding along the direction of the crack is reciprocating grinding with sandpaper in a grinding path parallel to the crack; the angle between the grinding path and the crack is 0-5°.

[0011] Preferably, the mesh number of medium-grain sandpaper is 120 mesh; the mesh number of fine sandpaper is 180 mesh; and the mesh number of ultrafine sandpaper is 320 mesh.

[0012] Preferably, the first grinding time is 3-10 min; the second grinding time is 15-20 min; and the third grinding time is 15-30 min.

[0013] Preferably, the combined coupling agent primer is a mixture obtained by mixing 3-aminopropyltriethoxysilane and 3-mercaptopropionic acid in a volume ratio of 1.12:0.78-1.43 and stirring at room temperature for 15 minutes.

[0014] Preferably, the sintering temperature in the second stage S3 is 1200-1220°C, and the holding time is 180-210 min; and the cooling rate in the third stage is 2.5°C / min.

[0015] A ceramic crack repair glaze, including repair glaze A and repair glaze B;

[0016] In parts by weight, the raw materials for repairing glaze A are: 32 parts of halloysite, 15-18 parts of phosphotarsite, 10-13 parts of leucite, 5-8 parts of wollastonite, 6 parts of barium carbonate, 5 parts of zinc oxide, 8 parts of zirconium silicate and 15-20 parts of modified mullite;

[0017] In parts by weight, the raw materials for repairing glaze B are: 32 parts of halloysite, 18 parts of phosphate quartz, 13 parts of white garnet, 5 parts of zinc oxide, 5-12 parts of medium-temperature frit, 6 parts of barium carbonate, 2-8 parts of tin oxide, 2-5 parts of titanium oxide, 20 parts of modified mullite, and 0.2-0.5 parts of polyvinyl alcohol.

[0018] Preferably, the raw materials for repairing glaze A and repairing glaze B are respectively put into a ball mill, and 28% water of the total mass of the raw materials for repairing glaze A and repairing glaze B is added respectively. After ball milling for 36 hours, the raw materials are sieved through 180 mesh to obtain repairing glaze A and repairing glaze B.

[0019] Preferably, mullite with a particle size of 25-50 μm is soaked in a boric acid solution with a mass concentration of 8% at room temperature for 60 minutes, and then filtered, washed and dried to obtain the modified mullite; the mass ratio of mullite to boric acid solution is 1:2.8.

[0020] Preferably, the raw materials for the repaired A glaze are, in parts by weight, 32 parts of halloysite, 18 parts of quartz, 13 parts of leucite, 8 parts of wollastonite, 6 parts of barium carbonate, 5 parts of zinc oxide, 8 parts of zirconium silicate and 20 parts of modified mullite.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] 1. Compared with fired ceramics, semi-finished ceramic bodies have lower mechanical strength and are prone to deformation and cracking. More caution is required during the grinding stage when repairing cracks. The grinding path affects the direction of the grinding force. Grinding along the crack direction will reduce the force applied laterally to the crack. The present invention adopts a step-by-step grinding method. By changing the angle between the grinding path and the crack and the grinding time, the secondary cracking of the ceramic is reduced, the bonding effect of the primer, the repair glaze and the body is enhanced, and the firing yield is 99.2%. There are no cracks or protrusions at the repair position after firing.

[0023] 2. The amino group in 3-aminopropyltriethoxysilane can combine with the hydroxyl group of the body and adhere tightly to the surface of the body at the crack; by introducing the thiol group in 3-mercaptopropionic acid, the chemical bonding force between the combined coupling agent primer and the ceramic body is enhanced, and the compatibility and bonding strength with the glaze are improved. By changing the volume ratio of 3-aminopropyltriethoxysilane and 3-mercaptopropionic acid, the body and the repair glaze are fully adhered. After firing, the glaze surface has good adhesion to the body, the repair glaze does not fall off, and the yield rate reaches 99.5%.

[0024] 3. A staged firing process is adopted. After applying the repair glaze A, the body is bisque fired to ensure that the repair glaze A is fully bonded to the body. After polishing and smoothing, the entire body is sprayed with the repair glaze B, and then fired at high temperature in stages. The staged temperature rise firing makes the repair glaze A and the repair glaze B tightly bonded to the body, enhancing the strength and thermal stability of the overall ceramic. The glaze surface of the fired ceramic repair area has a smooth transition with the surrounding area, without cracks, and has qualified thermal stability. The yield rate reaches 99.7%.

[0025] 4. Modified mullite was added to the repair glaze. Mullite has a low shrinkage rate, which can reduce the risk of cracking and shedding caused by glaze shrinkage during firing. Boric acid was used to modify the mullite, allowing the repair glaze A to chemically bond with the amino and thiol groups in the combined coupling agent base, reducing shedding and cracking, improving glaze fluidity, and enhancing smoothness. By adding modified mullite to the repair glaze A and varying the amount of leucite, leucite, and wollastonite, the cracking rate was reduced and the glaze strength was improved. After firing, the ceramic repair glaze showed no shedding, a smooth, crack-free surface, and a glaze strength of 250kPa.

[0026] 5. The raw materials for repairing glaze B use the same amount of halloysite, quartz, leucite, barium carbonate, zinc oxide, and modified mullite as those for repairing glaze A, to reduce the difference in thermal expansion coefficients between the two glazes and reduce the risk of cracking; polyvinyl alcohol and medium-temperature frit are added to increase the adhesion between the glazes; tin oxide and titanium oxide are added to make the fired ceramic white, concealing the color difference between the cracks caused by repairing glaze A and the surrounding body, and making the finished product uniform in color; by changing the amount of medium-temperature frit, polyvinyl alcohol, tin oxide, and titanium oxide added, the glaze layer viscosity is 291 Pa·s, and the fired ceramic has a whiteness value of 94.9%, a smooth surface, and uniform color. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 Schematic diagram of the yield of Examples 18, 22-36 of the present invention. DETAILED DESCRIPTION

[0028] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0029] See also Figure 1 The present invention provides a ceramic crack repair glaze and a glaze repair process, and the technical solution is as follows:

[0030] The substance information involved in the present invention is as follows:

[0031] Boric acid CAS: 10043-35-3; Barium carbonate CAS: 513-77-9; Zinc oxide CAS: 1314-13-2; Zirconium silicate CAS: 10101-52-7; Lepidolite CAS: 1317-64-2; Tin oxide CAS: 18282-10-5; Titanium oxide CAS: 12137-20-1; Polyvinyl alcohol CAS: 9002-89-5; 3-Aminopropyltriethoxysilane CAS: 919-30-2; 3-Mercaptopropionic acid CAS: 107-96-0.

[0032] Example 1

[0033] Preparation of Repair Glaze A: Mullite with a particle size of 25-50 μm is soaked in a boric acid solution with a mass concentration of 8% at room temperature for 60 minutes, then filtered, washed, and dried to obtain modified mullite; the mass ratio of mullite to boric acid solution is 1:2.8; 32 parts of halloysite, 15 parts of phosphotidite, 10 parts of leucite, 5 parts of wollastonite, 6 parts of barium carbonate, 5 parts of zinc oxide, 8 parts of zirconium silicate, and 15 parts of modified mullite are placed in a ball mill, and 28% of the total mass of the raw materials of Repair Glaze A is added. The mixture is ball-milled for 36 hours and then passed through a 180-mesh sieve to obtain Repair Glaze A.

[0034] Preparation of repair glaze B: Put 32 parts of halloysite, 18 parts of phosphate quartz, 13 parts of leucite, 3-11 parts of zinc oxide, 5 parts of medium-temperature frit, 6 parts of barium carbonate, 2 parts of tin oxide, 2 parts of titanium oxide, 15 parts of modified mullite, and 0.2 parts of polyvinyl alcohol into a ball mill, add 28% water of the total mass of the raw materials of repair glaze B, ball mill for 36 hours, and then pass through a 180-mesh sieve to obtain repair glaze B.

[0035] The glaze repair process steps are as follows:

[0036] S1 Use a soft brush to remove dust and debris from the cracks on the surface of the semi-finished ceramic body; First grinding: Use 120-mesh medium-grain sandpaper to grind the crack back and forth for 3 minutes in a grinding path parallel to the crack, with the grinding path and the crack angle being 0°, remove protruding debris, and make the interface on both sides of the crack flat, then use a brush to remove the dust generated by grinding and wipe it clean with a damp cloth; Second grinding: Use 180-mesh fine sandpaper to grind back and forth for 15 minutes in a grinding path parallel to the crack, with the grinding path and the crack angle being 0°, and further grind it smooth so that the repaired area is flush with the surrounding surface; Third grinding: Use 320-mesh ultra-fine sandpaper to grind back and forth for 15 minutes in a grinding path parallel to the crack, with the grinding path and the crack angle being 0°, wipe it clean with a soft brush and a damp cloth, and let it dry naturally to obtain a clean semi-finished ceramic body;

[0037] S2: 3-aminopropyltriethoxysilane and 3-mercaptopropionic acid are mixed in a volume ratio of 1.12:0.78 and stirred at room temperature for 15 minutes to obtain a combined coupling agent primer; the combined coupling agent primer is sprayed with a thickness of 0.1 mm on the cracks of the clean semi-finished ceramic body, and after it dries, the cracks are smeared with repair glaze A with a soft brush, and after drying, it is polished with fine sandpaper until it is flush with the surrounding body, and dust is removed to obtain a pretreated semi-finished ceramic body;

[0038] S3 puts the pretreated semi-finished ceramic body into the kiln for firing. The first stage is bisque firing, heating the body to 280°C at 2°C / min and keeping it warm for 60 minutes, then heating it to 800°C and firing it for 8 hours, then cooling it to room temperature at 2°C / min, spraying the repair B glaze evenly on its surface, and obtaining a bisque fired semi-finished body after drying; the second stage: heating the bisque fired semi-finished body to 180°C at 2°C / min and keeping it warm for 60 minutes, then heating it to the firing temperature of 1180°C at 3°C / min and keeping it warm for 60 minutes; the third stage: cooling it to room temperature at 1°C / min to obtain the finished ceramic.

[0039] Example 2-11

[0040] Refer to the preparation method and parameter conditions of Example 1, the specific differences are shown in Table 1.

[0041] Comparative Example 1

[0042] The preparation method and parameter conditions are similar to those of Example 7, except that the angle between the grinding path and the crack is 90°.

[0043] Comparative Example 2

[0044] The preparation method and parameter conditions are the same as those in Example 7, except that the polishing process is not performed.

[0045] Table 1 Grinding parameters of Examples 1-11 and Comparative Examples 1 and 2

[0046]

[0047] Example 12: Testing of surface cracks, flatness, and yield of finished ceramic products

[0048] The semi-finished green bodies with cracks of 1-2 cm were glazed and repaired using the glazing repair process of Examples 1-11 and Comparative Examples 1 and 2. The surface cracks and flatness of the finished ceramics after firing were observed, and the yield rate was calculated. The results are shown in Table 2.

[0049] Table 2 Surface cracks, flatness and yield of finished ceramics of Examples 1-11 and Comparative Examples 1 and 2

[0050]

[0051]

[0052] Grinding not only removes dirt, grease, and old glue from the surface of the semi-finished blank, but also removes burrs and uneven areas, ensuring direct contact between the repair material and the blank surface. This allows the combined coupling agent primer and repair glaze to adhere better to the surface of the semi-finished blank, preventing the repair layer from peeling. Grinding creates tiny grooves, allowing the combined coupling agent primer and repair glaze to better "lock" into these grooves, improving the durability of the repair. Using sandpaper of varying grit sizes in stages, from large to small, saves time while avoiding excessively thinning the blank and surface depressions in the finished product after firing due to prolonged grinding with high-grit sandpaper. Excessive angles between the grinding path and the crack can exert lateral stress on the surface of the semi-finished blank, making it more fragile at the crack and more susceptible to secondary cracking during subsequent firing, reducing the yield rate. As shown in Tables 1 and 2, in Examples 1-8, the final firing yield was improved by changing the time of the three grindings. In Example 7, the first, second, and third grinding times were 6 minutes, 18 minutes, and 25 minutes, respectively. The surface of the finished ceramic after firing was smooth and crack-free, with a yield of 99.2%. In Examples 8-10, the yield showed a downward trend by increasing the angle between the grinding path and the crack. In Example 10, when the angle was 5°, the yield dropped to 98.0%. In Comparative Example 1, the angle between the grinding path and the crack was 90°. During grinding, lateral force was applied to the body, resulting in obvious cracks and depressions on the surface of the fired ceramic. The yield was 87.1%. In Comparative Example 2, the semi-finished body was not polished. The dust and dirt at the cracks affected the bonding of the primer and repair glaze to the body, resulting in obvious cracks on the surface of the fired ceramic. The repaired area was depressed relative to the surrounding plane. The yield was 90.5%.

[0053] Examples 13-20

[0054] Refer to the preparation method and parameter conditions of Example 7, the specific differences are shown in Table 3.

[0055] Comparative Example 3

[0056] The preparation method and parameter conditions are similar to those of Example 7, except that no combined coupling agent primer is used.

[0057] Example 21: Testing of glaze peeling and yield rate of finished ceramic surface repair products

[0058] The glaze repair process of Examples 7, 13-20 and Comparative Example 3 was used to glaze and repair the semi-finished green bodies with cracks of 1-2 cm. The peeling of the repair glaze on the surface of the finished ceramics after firing was observed, and the yield was calculated. The results are shown in Table 3.

[0059] Table 3: Repair glaze shedding and yield rate of Examples 7, 13-20 and Comparative Example 3

[0060]

[0061] 3-Aminopropyltriethoxysilane is a silane coupling agent containing amino groups in its molecules, which can combine with the hydroxyl groups on the surface of the green body to form silicon-oxygen bonds, so that the combined coupling agent primer adheres tightly to the green body surface at the cracks, thereby increasing the active sites on the green body surface; the thiol group in 3-mercaptopropionic acid reacts with the hydroxyl groups on the surface of the ceramic green body through hydrogen bonds or more stable covalent bonds to form chemical adsorption, thereby increasing the bonding force between the green body and the green body, and strengthening the chemical bonding force between the combined coupling agent primer and the ceramic green body; while the combined coupling agent primer is tightly bonded to the semi-finished green body, it can also produce a cross-linking reaction with the repair glaze, forming a covalent bond with the glaze through the thiol group, thereby improving the cohesion and adhesion of the repair layer, improving the compatibility and bonding strength with the glaze, reducing the risk of the repair glaze falling off, and improving the yield rate. As shown in Table 3, in Examples 7, 13, and 16, the volume ratio of 3-aminopropyltriethoxysilane to 3-mercaptopropionic acid in the combined coupling agent primer was varied. The resulting ceramic repair glaze layer remained intact upon firing, improving the yield. In Example 13, the volume ratio of 3-aminopropyltriethoxysilane to 3-mercaptopropionic acid was 1.12:0.90, resulting in a 99.4% yield. The thickness of the combined coupling agent primer also affects the effectiveness of ceramic crack repair. If the thickness is insufficient, the combined coupling agent's adhesion to the green body and glaze surface is weak, resulting in no coupling effect. If the thickness is too great, the coupling agent completely covers the green body surface, making it difficult for the repair glaze to penetrate and contact the green body, which in turn reduces the bond strength between the repair glaze and the green body. This can lead to the formation of bubbles or cavities during firing, reducing the mechanical strength of the finished product. In Examples 13, 17-20, varying the thickness of the combined coupling agent primer improved the yield rate. In Example 18, the combined coupling agent primer was applied at a thickness of 0.6 mm, and the repair glaze remained intact, increasing the yield rate to 99.5%. In Comparative Example 3, where no combined coupling agent primer was used, the bond strength between the repair glaze and the body was reduced, resulting in the repair glaze peeling off in the fired finished ceramic, reducing the yield rate to 92.6%.

[0062] Examples 22-36

[0063] Referring to the preparation method and parameter conditions of Example 18, the specific differences are shown in Table 4.

[0064] Table 4 Firing parameters of Examples 18, 22-36

[0065]

[0066] Comparative Example 4

[0067] Referring to the preparation method and parameter conditions of the repair glaze in Example 1, the glaze repair process steps are as follows:

[0068] S1 Use a soft brush to remove dust and debris from the cracks on the surface of the semi-finished ceramic body; First grinding: Use 120-mesh medium-grain sandpaper to grind the crack back and forth for 6 minutes in a grinding path parallel to the crack, with the grinding path and the crack angle being 0°, remove protruding debris, and make the interface on both sides of the crack smooth, then use a brush to remove the dust generated by grinding and wipe it clean with a damp cloth; Second grinding: Use 180-mesh fine sandpaper to grind back and forth for 18 minutes in a grinding path parallel to the crack, with the grinding path and the crack angle being 0°, and further grind it smooth so that the repaired area is flush with the surrounding surface; Third grinding: Use 320-mesh ultra-fine sandpaper to grind back and forth for 25 minutes in a grinding path parallel to the crack, with the grinding path and the crack angle being 0°, wipe it clean with a soft brush and a damp cloth, and let it dry naturally to obtain a clean semi-finished ceramic body;

[0069] S2: 3-aminopropyltriethoxysilane and 3-mercaptopropionic acid are mixed in a volume ratio of 1.12:0.90 and stirred at room temperature for 15 minutes to obtain a combined coupling agent primer; the combined coupling agent primer is sprayed with a thickness of 0.6 mm on the cracks of the cleaned semi-finished ceramic body, and after it dries, glaze A is applied to the cracks with a soft brush for repair. After drying, glaze B is evenly sprayed on the surface, and the surface is polished with fine sandpaper until it is flush with the surrounding body. After removing dust, a pretreated semi-finished ceramic body is obtained;

[0070] S3 puts the pretreated semi-finished ceramic body into the kiln for firing, raises the temperature to 180°C at 2°C / min and keeps it at that temperature for 60 minutes, then raises the temperature to the firing temperature of 1180°C at 3°C / min, keeps it at that temperature for 60 minutes, and then cools it to room temperature at 1°C / min to obtain the finished ceramic.

[0071] Example 37 Thermal Stability, Appearance Effect and Yield Rate Test

[0072] The ceramics fired in Examples 18, 22-36 and Comparative Example 4 were subjected to a water heat exchange test at 180°C-20°C for thermal stability. The ceramics that did not crack were qualified. The appearance of the repaired parts was observed and the yield rate was calculated. The results are shown in Tables 5 and Figure 1 shown.

[0073] Table 5 Thermal stability, appearance and yield of Examples 18, 22-36 and Comparative Example 4

[0074]

[0075] During the first stage of heating to 280°C and holding for 60 minutes, the halloysite in Repair A glaze contains a certain amount of water, which dehydrates during this stage. Barium carbonate begins to decompose, releasing carbon dioxide gas, and lepidolite undergoes a dehydration reaction. Holding for 60 minutes allows the gas to fully escape and eliminate bubbles. During the bisque firing from 280°C to 800°C for 8 hours, phosphotidite, leucite, wollastonite, and zirconium silicate undergo phase transformations and partial melting. Modified mullite, a high-temperature stable phase with low shrinkage, undergoes no significant structural changes. Barium carbonate and zinc oxide are low-melting-point components that can melt at high temperatures, helping to improve the fluidity of Repair A glaze. Lepidolite helps lower the glaze's melting point and improve its solubility. At 800°C, Repair A glaze begins to melt, but does not completely melt, which helps evenly distribute the glaze on the body and improves the glaze's surface smoothness. The first stage of bisque firing helps to expel the bubbles in the repair glaze A and improve the thermal stability of the ceramic. In comparative example 4, no bisque firing was performed, and the repair glaze A was directly sprayed with glaze B after drying, and then fired once after drying. The thermal stability of the finished ceramic was unqualified, and the repaired area was uneven, cracked and had small bubbles. During the second stage of firing, the halloysite, quartz, leucite and medium-temperature frit in the repair glaze B melted to provide a matrix for the glaze and form a uniform glaze surface, which helps the fluidity and covering ability of the glaze. Zinc oxide forms zinc silicate at high temperature, which improves the thermal stability of the glaze. Barium carbonate will decompose and react with zirconium silicate in the glaze to form barium silicate, which increases the refractive index of the glaze and improves the glossiness. Tin oxide can reduce the expansion coefficient of the glaze and improve the thermal stability of the glaze. The modified mullite undergoes a phase change at high temperature, which improves the thermal stability of the glaze. As shown in Tables 4, 5 and Figure 1 As shown, in Examples 18, 22-25, when the firing temperature is 1180-1260°C, the yield is 99.4%-99.6%, and the fired ceramics have qualified thermal stability, are flat, and have no cracks or bubbles. In Examples 22-23, the yield reaches 99.6% when the firing temperature is 1200-1220°C. Sufficient holding time ensures that the chemical reaction in the glaze can proceed fully, and the formation of stable compounds helps the glaze to melt evenly, reduces unevenness and particles on the glaze surface, is conducive to gas escape, and reduces glaze bubbles. Long-term heat preservation helps to reduce internal stress caused by temperature gradients, reduce the risk of glaze cracking, and improve thermal stability. In Examples 29 and 30, the holding time is 180min and 210min respectively, and the yield is 99.6%. During the ceramic firing process, a slow cooling rate helps to prevent the glaze and the body from cracking due to rapid temperature changes. In Examples 32-36, the cooling rate is 1-3.5°C / min. When the cooling rate reaches 3.5°C / min as in Example 36, the cooling rate is too fast, and the difference in expansion coefficient between the repaired glaze A and the repaired glaze B causes small cracks to appear in the finished ceramic. In Example 34, the cooling rate is 2.5°C / min, and the repaired part of the finished ceramic is smooth, without cracks or bubbles, and the finished product rate is 99.7%.

[0076] Examples 38-45

[0077] Referring to the preparation method and parameter conditions of Example 34, the specific differences are shown in Table 6.

[0078] Table 6 Addition amount of raw materials for repairing glaze A in Examples 34, 38-45

[0079]

[0080]

[0081] Comparative Example 5

[0082] The preparation method and parameter conditions are similar to those of Example 45, except that the mullite is not modified with boric acid.

[0083] Comparative Example 6

[0084] The preparation method and parameter conditions are similar to those of Example 45, except that modified mullite is not added.

[0085] Example 46: Testing of glaze peeling, finished ceramic appearance, and glaze layer strength of repaired glaze A

[0086] The repair glaze A of Examples 34, 38-45 and Comparative Examples 5 and 6 was cast into a solid glaze rod in a plaster mold, and the flexural strength of the dried glaze rod was measured to indicate the glaze layer strength of the repair glaze A. After firing, the repair glaze was observed to see if it fell off and the appearance of the finished product. The results are shown in Table 7.

[0087] Table 7: Glaze shedding, appearance and glaze strength of repaired glaze A in Examples 34, 38-45, Comparative Examples 5 and 6

[0088]

[0089] Mullite has a low shrinkage rate. When added to the repair glaze A, it reduces the risk of cracking and shedding caused by shrinkage during firing. The hydroxyl groups on the mullite surface react with one end of the silane molecules in the combined coupling agent primer, and the other end of the combined coupling agent bonds with the hydroxyl groups in the body, increasing the viscosity of the repair glaze A and reducing the risk of shedding. Boric acid modification of the mullite allows the repair glaze A to chemically bond with the amino and thiol groups in the combined coupling agent primer, reducing shedding and cracking. The boric acid-modified mullite imparts improved fluidity and wettability to the repair glaze A, facilitating its uniform spreading across the primer surface and improving smoothness. Borate ions form stable coordination bonds with the amino groups in the combined coupling agent primer and form thiol-boric acid adducts with thiol groups. This crosslinking strengthens the silane coupling agent network, thereby improving adhesion between the repair glaze A and the primer. The introduction of borate improves the heat resistance of the silane coupling agent layer. Under high temperature conditions, borate helps to maintain the stability of the coupling agent layer and prevents it from degrading and losing its viscosity; borate interacts with the hydroxyl groups on the surface of mullite, improves the interfacial compatibility between the combined coupling agent and the repair glaze A, helps to improve the interfacial bonding strength, and reduces the risk of falling off and secondary cracking; as shown in Tables 6 and 7, in Comparative Example 5, the mullite was not modified with boric acid, the fired ceramic repair glaze fell off, and there were protrusions and obvious cracks at the repaired area. The glaze layer strength of the repair glaze A was 202 kPa; in Comparative Example 6, no modified mullite was added, the fired ceramic repair glaze fell off, and there were protrusions and obvious cracks at the repaired area. The glaze layer strength of the repair glaze A was 185 kPa. Phosphoquartz can lower the melting point of glaze, making it melt at a lower temperature, which helps to reduce energy consumption. Adding a proper amount of phosphoquartz can reduce thermal stress, prevent glaze cracking, and improve the gloss and transparency of the glaze. However, excessive addition will cause the glaze melting point to be too low, the fluidity to be too high, and the glaze to have problems such as glaze flow or insufficient viscosity; white garnet can lower the melting temperature of glaze, increase the mechanical strength of glaze, and help to form a uniform glaze layer at a lower temperature, but excessive addition will cause the glaze to be too rough, the gloss to decrease, and even cracking to occur; wollastonite can improve the thermal stability of glaze, reduce thermal cracking, and adjust the viscosity of glaze. Adding a proper amount will help control the fluidity and spreadability of glaze, but excessive addition will cause the glaze to have excessive viscosity and poor fluidity, resulting in an uneven glaze surface. In Examples 34, 38-45, the addition amounts of phosphotasquartz, leucite, wollastonite and modified mullite in the repair glaze A were adjusted, and the fired ceramic repair glazes did not fall off, the surface was smooth and crack-free, and the glaze layer strength of the repair glaze A was 233-250 kPa; in Example 45, 18 parts of phosphotasquartz, 13 parts of leucite, 8 parts of wollastonite and 20 parts of modified mullite were added to the repair glaze A, and the glaze layer strength of the repair glaze A reached 250 kPa.

[0090] Examples 47-51

[0091] Referring to the preparation method and parameter conditions of Example 45, the specific differences are shown in Table 8.

[0092] Comparative Example 7

[0093] The preparation method and parameter conditions are similar to those of Example 45, except that tin oxide and titanium oxide are not added.

[0094] Table 8 Addition amount of raw materials for repairing glaze B in Examples 45, 47-53 and Comparative Example 7

[0095]

[0096]

[0097] Example 53: Glaze Viscosity, Finished Ceramic Appearance, and Whiteness Value Test

[0098] The viscosity of the glaze for repairing B in Examples 45, 47-53, and Comparative Example 7 was tested using an oscillating viscometer. The whiteness values ​​of the finished ceramics obtained in Examples 45, 47-53, and Comparative Example 7 were tested according to the "QB-T1503-2011 Whiteness Determination Method for Daily-Use Ceramics," and the appearance of the finished ceramics was observed. The results are shown in Table 9.

[0099] Table 9 Glaze viscosity, finished ceramic appearance and whiteness value of Examples 45, 47-53 and Comparative Example 7

[0100]

[0101] The addition amounts of halloysite, quartzite, leucite, modified mullite, zinc oxide, and barium carbonate in Repair Glaze B are consistent with those in Repair Glaze A, ensuring that the thermal expansion coefficient and shrinkage of Repair Glaze B are similar to those of Repair Glaze A, thereby reducing cracking caused by firing. The addition amount of medium-temperature frit affects the glaze's melting temperature, viscosity, and fluidity. While an appropriate amount of frit can improve the glaze's gloss and mechanical strength, an excessive amount can lead to excessive viscosity, affecting its fluidity and the quality of the final product. Tin oxide improves the glaze's opacity and whiteness, and its addition amount can affect its viscosity and sintering behavior. An appropriate amount of tin oxide can increase the glaze's gloss and whiteness, but an excessive amount can make it too viscous. Titanium oxide also improves the glaze's opacity and whiteness, and its addition amount also affects its viscosity and fluidity. An appropriate amount of titanium oxide can impart good whiteness and covering power. Polyvinyl alcohol, a binder and thickener, affects its viscosity and fluidity, which in turn affects the sprayability of the glaze on the ceramic body. As shown in Tables 8 and 9, increasing the amount of medium-temperature frit, tin oxide, titanium oxide, and polyvinyl alcohol added in Examples 45, 47-53 also resulted in an upward trend in glaze viscosity and whiteness. In Example 52, Repair Glaze B was prepared by adding 12 parts of medium-temperature frit, 5 parts of tin oxide, 5 parts of titanium oxide, and 0.3 parts of polyvinyl alcohol. The glaze viscosity of Repair Glaze B was 291 Pa·s, the whiteness was 94.9%, and the fired ceramic surface was smooth and uniform in color. In Comparative Example 7, Repair Glaze B was prepared without the addition of tin oxide and titanium oxide. The glaze's hiding power decreased, and its whiteness significantly decreased. The glaze viscosity of Repair Glaze B was 271 Pa·s, the whiteness was 82.0%, and the fired ceramic surface was smooth, with color differences at the repaired area.

[0102] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A ceramic crack glazing repair process, characterized by: The following steps are involved: S1: Use a soft brush to remove dust and debris from the cracks on the surface of the semi-finished ceramic body; first grinding: Use medium-grained sandpaper to grind the crack along the direction of the crack to remove protruding debris and make the interface on both sides of the crack smooth, then use a brush to remove the dust generated by grinding and wipe it clean with a damp cloth; second grinding: Use fine sandpaper to further grind it smooth along the direction of the crack to make the repaired area flush with the surrounding surface; third grinding: Use ultra-fine sandpaper to grind along the direction of the crack, wipe it clean and let it dry naturally to obtain a clean semi-finished ceramic body; S2 spraying a combined coupling agent primer with a thickness of 0.1-0.8 mm on the cracks of the clean semi-finished ceramic body, and applying a ceramic crack repair glaze A glaze on the cracks after the primer dries. After drying, polishing with the fine sandpaper until it is flush with the surrounding body, and removing dust to obtain a pre-treated semi-finished ceramic body; S3: placing the pretreated semi-finished ceramic body into a kiln for firing. The first stage is bisque firing, wherein the temperature is raised to 280°C at 2°C / min and held for 60 minutes, then raised to 800°C and fired for 8 hours, then cooled to room temperature at 2°C / min, and the ceramic crack repair glaze B is evenly sprayed on the surface. After drying, a bisque-fired semi-finished body is obtained. The second stage is: raising the temperature of the bisque-fired semi-finished body to 180°C at 2°C / min and holding for 60 minutes, then raising the temperature to a firing temperature of 1200-1220°C at 3°C / min, and holding for 180-210 minutes. The third stage is: cooling to room temperature at 2.5°C / min to obtain a finished ceramic. The ceramic crack repair glaze used includes the repair glaze A and the repair glaze B; The raw materials of the repair glaze A are, in parts by weight, 32 parts of halloysite, 15-18 parts of phosphotarite, 10-13 parts of leucite, 5-8 parts of wollastonite, 6 parts of barium carbonate, 5 parts of zinc oxide, 8 parts of zirconium silicate and 15-20 parts of modified mullite; In parts by weight, the raw materials of the repair glaze B are: 32 parts of halloysite, 18 parts of phosphotarsite, 13 parts of leucite, 5 parts of zinc oxide, 5-12 parts of medium-temperature frit, 6 parts of barium carbonate, 2-8 parts of tin oxide, 2-5 parts of titanium oxide, 20 parts of modified mullite, and 0.2-0.5 parts of polyvinyl alcohol; The grinding path along the direction of the crack is reciprocating grinding in a grinding path parallel to the crack; the angle between the grinding path and the crack is 0-5°; The combined coupling agent primer is a mixture of 3-aminopropyltriethoxysilane and 3-mercaptopropionic acid in a volume ratio of 1.12:0.78-1.43, and stirred at room temperature for 15 minutes; Mullite with a particle size of 25-50 μm is soaked in a boric acid solution with a mass concentration of 8% at room temperature for 60 minutes, then filtered, washed and dried to obtain the modified mullite; the mass ratio of the mullite to the boric acid solution is 1:2.

8.

2. The ceramic crack glazing repair process according to claim 1, characterized in that: The mesh number of the medium-grained sandpaper is 120 mesh; the mesh number of the fine sandpaper is 180 mesh; and the mesh number of the ultrafine sandpaper is 320 mesh.

3. The ceramic crack glazing repair process according to claim 1, characterized in that: The first grinding time is 3-10 minutes; the second grinding time is 15-20 minutes; and the third grinding time is 15-30 minutes.

4. The ceramic crack glazing repair process according to claim 1, characterized in that: The raw materials of the repair glaze A and the repair glaze B are respectively put into a ball mill, and 28% water of the total mass of the raw materials of the glaze A and the glaze B is added respectively. After ball milling for 36 hours, the raw materials are passed through a 180-mesh sieve to obtain the repair glaze A and the repair glaze B.

5. The ceramic crack glazing repair process according to claim 1, characterized in that: In parts by weight, the raw materials of the repair glaze A are: 32 parts of halloysite, 18 parts of quartz, 13 parts of leucite, 8 parts of wollastonite, 6 parts of barium carbonate, 5 parts of zinc oxide, 8 parts of zirconium silicate and 20 parts of modified mullite.

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