A method for preparing a ceramic shrinkage pad

Abstract

The application discloses a kind of preparation methods of ceramic synchronous shrinkage backing plate, belong to sanitary ceramic production process technical field, including the following steps: S1, the ceramic raw material including green gangue, cotton gangue, clay and water reducing agent is uniformly mixed, and mixture is obtained;Wherein, the total mass percentage of green gangue and cotton gangue is not less than 70%;S2, water is added to the mixture to carry out wet grinding, and clay slurry is obtained after sieving;S3, the clay slurry is stationary, then granules are prepared by spray drying;S4, the granules are pressed into brick blank;S5, the brick blank is dried, and dry blank is obtained;S6, the dry blank is fired at 960 DEG C to 1000 DEG C, and fired blank is obtained;S7, the surface of the fired blank is applied with isolation layer material, and synchronous shrinkage backing plate with integrated isolation layer on surface is prepared;The backing plate has substantially synchronous firing shrinkage with the sanitary ceramic body carried after being fired at the temperature, effectively preventing product bottom edge deformation.

Description

Technical Field

[0001] This invention belongs to the field of sanitary ceramics production technology, specifically relating to a method for preparing a ceramic synchronous shrinkage pad. Background Technology

[0002] As people's living standards improve, large-sized and complex-shaped sanitary ceramic products are increasingly favored for their durability and aesthetic appeal. However, these products are prone to deformation at the bottom edge due to uneven shrinkage during firing. To ensure the regularity of the bottom edge, the commonly used method is to place a layer of clay pad, formed by casting plaster molds, between the product and the kiln base as a disposable auxiliary kiln tool, utilizing its firing shrinkage to offset stress.

[0003] However, existing clay mats have several drawbacks: production relies on manual slurrying and powdering, resulting in low efficiency and high costs; their strength after drying is extremely low, making them prone to breakage and cracking; severe slag shedding and soiling during firing affects the product's appearance; and the raw materials must match the product, leading to high material costs. To overcome these problems, the industry has attempted to use bisque-fired mats instead of clay mats, but existing bisque-fired mats either have excessively low shrinkage rates in pursuit of strength, which do not match the actual shrinkage rates of sanitary ceramic products, making synchronous shrinkage impossible and causing product deformation; or they still require manual application of release powder, failing to completely solve the problems of cumbersome operation and soiling.

[0004] Therefore, how to provide a synchronous shrinkage pad that matches the shrinkage height of the product, has high strength, does not require manual powdering of the surface and does not shed residue, and has a lower cost has become a technical problem that urgently needs to be solved in this field.

[0005] The information disclosed in this background section is intended only to enhance the understanding of the overall background of the invention and should not be construed as an admission or in any way implying that the information constitutes prior art known to those skilled in the art. Summary of the Invention

[0006] The purpose of this invention is to provide a method for preparing a synchronous shrinkage pad that is low in cost, has good firing performance, shrinks synchronously with the product, and does not shed slag on the surface.

[0007] To achieve the above objectives, a specific embodiment of the present invention provides the following technical solution: A method for preparing a ceramic synchronous shrinkage pad includes the following steps: S1. The ceramic raw materials comprising silage gangue, cotton gangue, clay, and water-reducing agent are mixed evenly to obtain a mixture; wherein the total mass percentage of silage gangue and cotton gangue is not less than 70%; S2. Add water to the mixture and perform wet grinding. After sieving, obtain clay slurry. S3. The clay slurry is allowed to stand, and then spray-dried to form granules; S4. Press the granules into brick blanks; S5. Dry the brick blank to obtain a dry blank; S6. The dry blank is fired at 960℃~1000℃ to obtain a fired blank; S7. Apply an isolation layer material to the surface of the fired billet, so that the isolation layer material is sintered with the billet to obtain a synchronous shrinkage pad with an integrated isolation layer on the surface. The synchronous shrinkage pad has a firing shrinkage rate that is basically synchronized with the sanitary ceramic body it supports after firing, and its room temperature flexural strength is higher than that of the mud pad.

[0008] In one or more embodiments of the present invention, the raw materials mentioned in step S1 include, by mass percentage: 8%–12% Linfeng cotton gangue, 8%–12% Zhihui cotton gangue, 21%–26% Xulinyuan green gangue, 33%–38% Linfeng green gangue, 3%–6% Nanyang soil, 6%–11% Xinyang soil, 6%–11% Ruyang soil, 0.3%–0.6% water glass, and 0.1%–0.2% sodium carbonate.

[0009] In one or more embodiments of the present invention, in step S2, the amount of water added is 45% to 50% of the weight of the mixture, the grinding time is 8 to 11 hours, and the mixture is passed through a 60-mesh sieve.

[0010] In one or more embodiments of the present invention, in step S3, the settling time is 48 hours, and the moisture content of the particles is 6% to 7.2%.

[0011] In one or more embodiments of the present invention, in step S6, the isolation layer material is one or more of alumina powder slurry, kaolin slurry or talc powder slurry, and the coating thickness is 0.1 to 0.3 mm.

[0012] In one or more embodiments of the present invention, in step S7, the heating rate during firing is 30°C to 40°C / min, and the holding time is 3 to 5 min.

[0013] In one or more embodiments of the present invention, the synchronous shrinkage pad has a firing shrinkage rate of 6.5% to 8.5% after firing at 960℃ to 1000℃, a room temperature flexural strength ≥ 8.0 MPa, and when it is fired at the same temperature curve as the sanitary ceramic body it supports, the absolute value of the difference in firing shrinkage rate between the two is ≤ 0.5%.

[0014] In one or more embodiments of the present invention, the surface roughness Ra of the synchronous shrinkage pad is ≤1.6μm.

[0015] In one or more embodiments of the present invention, the chemical composition of the synchronous shrinkage pad, by mass percentage, comprises: LOSS 8.5%–10.2%, SiO2 55%–59%, Al2O3 24%–27%, Fe2O3 2.0%–2.8%, TiO2 1.2%–1.8%, CaO 0.5%–1.0%, MgO 0.2%–0.4%, K2O 1.0%–1.3%, and Na2O 0.2%–0.3%.

[0016] In one or more embodiments of the present invention, the chemical composition of the synchronous shrinkage pad, by mass percentage, is: LOSS 9.37%, SiO2 57.53%, Al2O3 25.97%, Fe2O3 2.4%, TiO2 1.63%, CaO 0.82%, MgO 0.27%, K2O 1.17%, Na2O 0.265%.

[0017] Compared with existing technologies, the method for preparing the ceramic synchronous shrinkage pad of the present invention significantly reduces raw material costs by ensuring that the total proportion of green gangue and cotton gangue in the raw materials is not less than 70%. By applying an isolation layer to the surface of the dry blank and firing it integrally with the blank at 960℃~1000℃, the manual slurry injection and powder brushing processes are eliminated, enabling mechanized production. This also creates a dense and smooth integrated isolation layer on the surface of the pad, preventing slag and dirt from falling off during firing. At the same time, after firing at this temperature, the pad has a firing shrinkage rate that is basically synchronized with the sanitary ceramic blank it supports, and its room temperature flexural strength is higher than that of traditional mud pads. Therefore, it is not easily damaged during handling and use, and it can shrink in coordination with the product, effectively preventing deformation of the bottom edge of the product. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a flowchart of the preparation process of the present invention; Figure 2 This is a pie chart showing the optimal raw material ratio for Example 2 of the present invention. Figure 3 This is a firing temperature curve of the present invention; Figure 4 This is a schematic diagram illustrating the synchronization and shrinkage matching between the synchronous shrinkage pad and the product of the present invention; Figure 5 This is a table of chemical composition of the synchronous shrinkage pad obtained by the present invention; Figure 6 These are the chemical compositions of the raw materials used in this invention; Figure 7 This is a table of raw material proportions for each embodiment; Figure 8 This is a table of processing parameters for each embodiment. Detailed Implementation

[0020] To enable those skilled in the art to better understand the technical solutions in this disclosure, the technical solutions in the embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this disclosure, and not all embodiments. Based on the embodiments in this disclosure, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this disclosure.

[0021] like Figures 1 to 8 As shown, a method for preparing a ceramic synchronous shrinkage pad in one embodiment of the present invention is described. The raw materials used in various embodiments of the present invention are as follows: Water glass refers to sodium metasilicate, commonly known as sodium silicate, with the chemical formula Na2O·nSiO2·mH2O. n is called the water glass modulus. In this embodiment, n=2.3~2.8 is selected as the water reducing agent.

[0022] Sodium carbonate, chemical formula Na2CO3, is used as a decoagulant to enhance the fluidity of mud.

[0023] Green gangue and cotton gangue are high-alumina natural raw materials with high refractory temperature, large high-temperature shrinkage, and strong high-temperature load-bearing capacity.

[0024] Example 1: Raw material ratio by mass percentage: Linfeng cotton gangue 10%, Zhihui cotton gangue 10%, Xulinyuan green gangue 25%, Linfeng green gangue 35%, Nanyang soil 4%, Xinyang soil 8%, Ruyang soil 8%, sodium carbonate 0.2%, water glass 0.3%. Total 100%, of which green gangue and cotton gangue account for 80%.

[0025] Add the above raw materials to a ball mill, then add water equivalent to 45% of the total weight of the raw materials, wet grind for 9 hours, and pass through a 60-mesh sieve to obtain clay slurry.

[0026] The clay slurry was left to stand for 48 hours, and then processed into granules with a moisture content of 6.5% by spray drying tower.

[0027] The granules are fed into an automatic brick press and pressed into brick blanks; the size can be adjusted as needed, for example, 300mm×300mm×15mm.

[0028] The brick blanks are sent into a drying kiln and dried until the moisture content is less than 1%, thus obtaining dry bricks.

[0029] The dry billet is fed into a roller kiln and heated to 960°C at a rate of 30°C / min. It is held at that temperature for 6 minutes and then naturally cooled to room temperature to obtain the fired billet.

[0030] The isolation layer is applied by spraying. A layer of alumina slurry with a solid content of about 40% is evenly sprayed on the surface of the fired blank. The wet thickness of the coating is about 0.2 mm, and the thickness after drying is about 0.15 mm, thus producing a synchronous shrinkage pad.

[0031] The flexural strength was determined according to national standard GB / T 3810.4-2016, and the firing shrinkage rate was determined according to GB / T 3810.2-2016. The results showed that the firing shrinkage rate was 6.8%, the flexural strength at room temperature was 8.5 MPa, and the surface roughness Ra=1.5 μm. The pad was fired in the same kiln as a sanitary ceramic body with a shrinkage rate of 7.1%, and the difference in shrinkage rate between the two was 0.3%. There was no slag on the surface of the pad, and the bottom edge of the product was not deformed.

[0032] Example 2: Figures 1 to 8 As shown, the raw material ratio (by mass percentage) is as follows: Linfeng cotton gangue 8%, Zhihui cotton gangue 12%, Xulinyuan green gangue 25%, Linfeng green gangue 33%, Nanyang soil 6%, Xinyang soil 6%, Ruyang soil 10%, sodium carbonate 0.1%, and water glass 0.5%. The total is 100%, and the total amount of green gangue and cotton gangue is 78%.

[0033] For slurry preparation, add 47% water, wet grind for 10 hours, and pass through a 60-mesh sieve.

[0034] Granules were prepared by standing for 48 hours and then spray drying to obtain granules with a moisture content of 7.0%.

[0035] The molding process is the same as in Example 1.

[0036] Drying is the same as in Example 1.

[0037] The temperature was raised to 980℃ at a rate of 35℃ / min, held for 8 minutes, and then cooled to room temperature to obtain a fired blank. An isolation layer was applied by spraying a layer of kaolin slurry with a solid content of 45% evenly sprayed onto the surface of the fired blank. The wet coating thickness was 0.25 mm, and the dry thickness was approximately 0.2 mm.

[0038] The firing shrinkage rate is 7.2%, the flexural strength at room temperature is 9.2 MPa, and the surface roughness Ra=1.3 μm. It was fired in the same kiln as a sanitary ceramic body with a shrinkage rate of 7.4%, with a shrinkage rate difference of 0.2%; the product has a regular bottom edge and no dirt.

[0039] X-ray fluorescence spectroscopy analysis revealed the following chemical composition of the pad: Figure 6As shown: LOSS 9.37%, SiO2 57.53%, Al2O3 25.97%, Fe2O3 2.4%, TiO2 1.63%, CaO 0.82%, MgO 0.27%, K2O 1.17%, Na2O 0.265%, totaling 99.84%.

[0040] Example 3: As Figures 1 to 8 As shown, the raw material ratio (by mass percentage) is as follows: Linfeng cotton gangue 12%, Zhihui cotton gangue 12%, Xulinyuan green gangue 23%, Linfeng green gangue 33%, Nanyang soil 3%, Xinyang soil 11%, Ruyang soil 6%, sodium carbonate 0.2%, and water glass 0.6%. The total is 100%, with green gangue and cotton gangue making up 80% of the total.

[0041] Add 50% water, wet grind for 11 hours, and pass through a 60-mesh sieve.

[0042] After standing for 48 hours, spray drying was performed to obtain granules with a moisture content of 7.5%.

[0043] The molding process is the same as in Example 1.

[0044] Drying is the same as in Example 1.

[0045] The temperature is increased to 1000℃ at a rate of 40℃ / min, held for 10 minutes, and then cooled to room temperature to obtain the fired blank.

[0046] The isolation layer is applied by spraying. A talc slurry with a solid content of 35% is sprayed onto the surface of the fired blank. The wet coating thickness is 0.3 mm, and the thickness after drying is about 0.25 mm.

[0047] The firing shrinkage rate is 8.3%, the room temperature flexural strength is 8.8MPa, and the surface roughness Ra=1.4μm; it is fired in the same kiln as a sanitary ceramic body with a shrinkage rate of 8.0%, and the difference in shrinkage rate is 0.3%; the product is free from deformation and there is no powder shedding on the surface.

[0048] Comparative Example 1: Traditional mud mat; Using the same raw materials as in Example 2, the product was molded by slurry casting in a plaster mold, and then manually coated with alumina powder after natural drying. The measured room temperature flexural strength was only 1.2 MPa, the firing shrinkage rate was 7.5%, but the handling breakage rate was as high as 15%, the bottom edge deformation rate of the product after firing was about 8%, and it was seriously soiled.

[0049] Comparative Example 2: Ordinary bisque-fired sheet, without an isolation layer, with mismatched shrinkage rates; It uses commercially available unglazed slabs, with raw materials mainly consisting of porcelain stone and kaolin, and a content of less than 20% of green gangue and cotton gangue. After pre-firing at 1200℃, the shrinkage rate is only 1.2%, and the flexural strength is 12MPa. When fired in the same kiln as a product with a shrinkage rate of 7.0%, the mismatch in shrinkage causes the bottom edge of the product to warp and deform, with a deformation rate of about 12%.

[0050] The slurry fineness, loss on ignition, and firing shrinkage rate of Examples 1-3 of this invention are superior to those of Comparative Examples 1 and 2, and are matched with product shrinkage. This not only eliminates the need for manual slurry injection and powdering processes, achieving mechanized and efficient production, but also prevents slag shedding and dirt accumulation during firing. At the same time, the pad achieves a firing shrinkage rate of 6.5%~8.5% and a room temperature flexural strength ≥8.0MPa under this firing regime, with an absolute value of the shrinkage difference between the pad and the sanitary ceramic body it supports ≤0.5%. This makes it less prone to breakage during handling and use, and allows it to shrink synchronously with the product, effectively preventing deformation of the product's bottom edge and significantly improving the yield and appearance quality of the product.

[0051] It will be apparent to those skilled in the art that this disclosure is not limited to the details of the exemplary embodiments described above, and that this disclosure can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of this disclosure is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within this disclosure. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0052] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A method for preparing a ceramic synchronous shrinkage pad, characterized in that, Includes the following steps: S1. The ceramic raw materials comprising silage gangue, cotton gangue, clay, and water-reducing agent are mixed evenly to obtain a mixture; wherein the total mass percentage of silage gangue and cotton gangue is not less than 70%; S2. Add water to the mixture and perform wet grinding. After sieving, obtain clay slurry. S3. The clay slurry is allowed to stand, and then spray-dried to form granules; S4. Press the granules into brick blanks; S5. Dry the brick blank to obtain a dry blank; S6. The dry blank is fired at 960℃~1000℃ to obtain a fired blank; S7. Apply an isolation layer material to the surface of the fired blank to obtain a synchronous shrinkage pad with an integrated isolation layer on the surface. The synchronous shrinkage pad has a firing shrinkage rate that is basically synchronized with the sanitary ceramic body it supports after firing, and its room temperature flexural strength is higher than that of the mud pad.

2. The preparation method according to claim 1, characterized in that, The raw materials mentioned in step S1 include, by mass percentage: 8%–12% Linfeng cotton gangue, 8%–12% Zhihui cotton gangue, 21%–26% Xulinyuan green gangue, 33%–38% Linfeng green gangue, 3%–6% Nanyang soil, 6%–11% Xinyang soil, 6%–11% Ruyang soil, 0.3%–0.6% water glass, and 0.1%–0.2% sodium carbonate.

3. The preparation method according to claim 1, characterized in that, In step S2, the amount of water added is 45% to 50% of the weight of the mixture, the grinding time is 8 to 11 hours, and the mixture is passed through a 60-mesh sieve.

4. The preparation method according to claim 1, characterized in that, In step S3, the settling time is 48 hours, and the moisture content of the particles is 6% to 7.2%.

5. The preparation method according to claim 1, characterized in that, In step S6, the isolation layer material is one or more of alumina powder slurry, kaolin slurry or talc powder slurry, and the coating thickness is 0.1 to 0.3 mm.

6. The preparation method according to claim 1, characterized in that, In step S7, the heating rate during firing is 30℃~40℃ / min, and the holding time is 3~5min.

7. The preparation method according to claim 1, characterized in that, The synchronous shrinkage pad has a firing shrinkage rate of 6.5% to 8.5% after firing at 960℃ to 1000℃, a room temperature flexural strength ≥ 8.0MPa, and when it is fired at the same temperature curve as the sanitary ceramic body it supports, the absolute value of the difference in firing shrinkage rate between the two is ≤ 0.5%.

8. The preparation method according to claim 1, characterized in that, The surface roughness Ra of the synchronous shrinkage pad is ≤1.6μm.

9. The preparation method according to claim 1, characterized in that, The chemical composition of the synchronous shrinkage pad, by mass percentage, includes: LOSS 8.5%–10.2%, SiO2 55%–59%, Al2O3 24%–27%, Fe2O3 2.0%–2.8%, TiO2 1.2%–1.8%, CaO 0.5%–1.0%, MgO 0.2%–0.4%, K2O 1.0%–1.3%, and Na2O 0.2%–0.3%.

10. The preparation method according to claim 9, characterized in that, The chemical composition of the synchronous shrinkage pad, by mass percentage, is as follows: LOSS 9.37%, SiO2 57.53%, Al2O3 25.97%, Fe2O3 2.4%, TiO2 1.63%, CaO 0.82%, MgO 0.27%, K2O 1.17%, Na2O 0.265%.

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