A removable wax core for preparing hollow ceramics and a method for preparing hollow ceramics
By adopting a removable wax core with a three-dimensional mesh structure framework, the problem of fragile and easy damage to hollow ceramic products during production and use is solved, and high-quality molding and qualification rate of ceramic products are achieved.
Patent Information
- Application Number
- CN202411941693.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-26
- Publication Date
- 2025-04-04
AI Technical Summary
The existing hollow ceramic products are fragile and easy to damage during the production process, resulting in poor quality of the internal cavity, and are prone to low pass rate due to external deformation during use.
A removable wax core including wax raw material and a skeleton is employed, which has a three-dimensional mesh structure, mixed with additives and fillers through a dual planetary mixer to form a wax slurry, and then poured into the skeleton mold to make a wax core of a specific shape for complete removal after ceramic molding.
It improves the strength and stability of the wax core, reduces deformation during transportation and use, significantly improves the pass rate of hollow ceramic products, and ensures high quality and pollution-free internal cavity.
Abstract
Description
Technical Field
[0001] The invention relates to the preparation of ceramics, in particular to a removable wax core for preparing hollow ceramics and a preparation method of the hollow ceramics. Background Art
[0002] The common preparation method for hollow ceramic products is the cold bonding method, which involves pressing the upper and lower layers of the ceramic product separately and then bonding them with an inorganic adhesive. The ceramic product prepared by this method will have a flat interface in the middle. If the bonding strength of the ceramic adhesive on the interface is insufficient and the bonding is uneven, the upper and lower parts will separate.
[0003] However, this phenomenon will not occur in hollow ceramic products prepared by the one-piece molding method. The filler is made into the shape of the required internal cavity, and the prepared filler is added when the ceramic powder is spread. The position and thickness of the upper and lower layers of powder are controlled, and the same raw material is used for one-time molding. Therefore, there will be no flat interface. The entire ceramic product is a complete component, not made of multiple ceramic components bonded together, and has better consistency and strength.
[0004] The plate-shaped hollow ceramics prepared with wax cores have the advantages of uniform structure and no bonding interface. However, due to the requirements of structural design, the internal cavity of some products is often only 1-3mm thick and the shape is extremely complex, which puts higher requirements on the wax core in production operations. The wax cores currently used are easily damaged or broken during normal storage and transportation due to their brittle material, which will affect the quality of the internal cavity of the final ceramic product. In addition, during the use and arrangement of the wax core, the wax core is often slightly deformed due to external force, resulting in a low pass rate of ceramic products. Summary of the invention
[0005] In order to solve the above problems, the present invention provides a removable wax core for preparing hollow ceramics, and the specific technical solution is as follows:
[0006] A removable wax core for preparing hollow ceramics comprises a wax raw material and a skeleton, wherein the skeleton is mixed in the wax raw material and has a three-dimensional network structure.
[0007] Preferably, the wax core comprises the following raw materials in parts by mass: 75-100 parts of wax slurry raw material, 0-10 parts of additives, and 5-15 parts of fillers.
[0008] Preferably, the wax slurry raw materials include the following raw materials in parts by mass: 5-95 parts of soft wax; 2-30 parts of beeswax; 20-80 parts of No. 58 semi-refined paraffin or 5-80 parts of No. 56 fully refined paraffin.
[0009] Preferably, the additive comprises the following raw materials in parts by mass: 0 to 1 part of polyethylene; 2 to 12 parts of stearic acid.
[0010] Preferably, the filler comprises graphite.
[0011] Preferably, the skeleton comprises polyurethane cotton or sponge, wherein the density of the polyurethane cotton is 10 to 25 ppi.
[0012] A method for preparing hollow ceramics comprises the following steps:
[0013] Step 1: Weigh the raw materials of each component according to the ratio, stir and mix them with a double planetary mixer for 1-4 hours, add additives and fillers, and stir for 1-4 hours to obtain wax slurry;
[0014] Step 2: pouring the wax slurry into the mold with the skeleton, removing the excess surface after cooling, and obtaining a wax core of the desired shape;
[0015] Step 3: placing the wax core in a mold filled with ceramic powder, then continuing to cover the mold with ceramic powder, and dry pressing under a certain pressure to obtain a ceramic green body;
[0016] Step 4: After the green body is dried, the wax is removed and then fired to obtain a hollow ceramic product.
[0017] Preferably, in step three, the wax core is heated from 20° C. to 120° C. at a rate of 3° C. / h, and kept warm for 2 to 12 hours to discharge the wax.
[0018] Preferably, in step 4, after the wax is removed, the product is placed in a kiln for firing at a temperature of 1000 to 1650° C. for a holding time of 2 to 24 hours, and then cooled naturally to obtain a hollow plate-shaped ceramic product.
[0019] Compared with the prior art, the present invention has the following beneficial effects:
[0020] The removable wax core for preparing hollow ceramics provided by the present invention has the advantages of high strength, removability, no residue, small rebound under pressure, and low volume expansion. The deformation occurring during use is also greatly reduced, and the qualified rate of hollow ceramic products is greatly improved. DETAILED DESCRIPTION
[0021] The present invention will be further described with reference to the embodiments.
[0022] By adding polyurethane cotton and sponge as the skeleton, the strength of the wax core itself has been greatly improved, the damage rate during transportation and storage has been greatly reduced, the deformation during use has also been greatly reduced, and the product qualification rate has been greatly improved. The addition of polyurethane will not increase the pressure rebound of the wax core during the ceramic embryo molding process and cause cracking.
[0023] During the debinding process, the wax component in the wax core can be softened and melted by controlling the temperature rise, and slowly discharged, leaving only the polyurethane as the skeleton. The polyurethane is then burned away during the ceramic firing, and the wax core is completely removed without any residue, ensuring a high-quality, pollution-free cavity inside the hollow ceramic product.
[0024] A method for preparing a removable wax core for preparing hollow ceramics is as follows:
[0025] Step 1: Weigh wax slurry raw materials (5-80 parts of soft wax; 2-30 parts of beeswax; 20-80 parts of No. 58 semi-refined paraffin or 5-80 parts of No. 56 fully refined paraffin) according to the ratio, stir and mix them with a double planetary mixer for 1-4 hours, add additives and fillers (0-1 part of polyethylene; 2-12 parts of stearic acid; 5-15 parts of graphite), and stir for 1-4 hours to obtain wax slurry;
[0026] Step 2: pouring the wax slurry into a mold containing a polyurethane cotton skeleton, removing excess surface parts after cooling, and obtaining a wax core of a desired shape;
[0027] Step 3: placing the wax core in a mold filled with ceramic powder, then continuing to cover the mold with ceramic powder, and dry pressing under a certain pressure to obtain a ceramic green body;
[0028] Step 4: After the green body is dried, the wax is removed and then fired to obtain a hollow ceramic product.
[0029] Example 1
[0030] 1000g of soft wax, 1000g of beeswax, and 3000g of 58# semi-refined paraffin were added to a double planetary mixer and stirred into wax slurry, and then 300g of graphite, 125g of stearic acid, and 50g of polyethylene were added and stirred for 4 hours to make wax slurry, which was then poured into a mold with polyurethane cotton, and the excess surface was removed after cooling to obtain a wax core of a specific shape.
[0031] Place the wax core on top of the ceramic powder in the mold, and then continue to cover it with ceramic powder, and then dry press it at 100Mpa. After pressing and molding, let it stand for one day, put the green body into an oven and heat it up to 120℃ at 3℃ / h, and keep it warm for 6 hours. Then place it in a kiln for firing at 1600℃, keep it warm for 3h, and cool it naturally to obtain a hollow ceramic product, and the wax core is completely removed without residue.
[0032] Example 2
[0033] 500g of soft wax, 500g of beeswax, and 4000g of 58# semi-refined paraffin were added into a double planetary mixer and stirred into wax slurry. Then 300g of graphite, 150g of stearic acid, and 50g of polyethylene were added and stirred for 4 hours to form wax slurry. Then, the wax slurry was poured into the mold with sponge, and the excess part of the surface was removed after cooling. A wax core of a specific shape was obtained.
[0034] Place the wax core on top of the ceramic powder in the mold, and then continue to cover it with ceramic powder, and then dry press it at 60Mpa. After pressing and molding, let it stand for one day, put the green body into an oven and heat it up to 120℃ at 3℃ / h, and keep it warm for 6 hours. Then place it in a kiln for firing at 1300℃, keep it warm for 3h, and cool it naturally to obtain a hollow ceramic product, and the wax core is completely removed without residue.
[0035] Example 3
[0036] 1500g of soft wax, 1500g of beeswax, and 2000g of No. 56 fully refined paraffin wax were added into a double planetary mixer and stirred into wax slurry, and then 350g of graphite, 150g of stearic acid, and 25g of polyethylene were added and stirred for 4 hours to make wax slurry, which was then poured into a mold with polyurethane cotton, and the excess surface was removed after cooling to obtain a wax core of a specific shape.
[0037] Place the wax core on top of the ceramic powder in the mold, and then continue to cover it with ceramic powder, and then dry press it at 80Mpa. After pressing and molding, let it stand for one day, put the green body into an oven and heat it up to 120℃ at 3℃ / h, and keep it warm for 6 hours. Then place it in a kiln for firing at 1300℃, keep it warm for 5 hours, and cool it naturally to obtain a hollow ceramic product, and the wax core is completely removed without residue.
Claims
1. A removable wax core for preparing hollow ceramics, characterized in that: The invention comprises a wax raw material and a skeleton, wherein the skeleton is mixed in the wax raw material and has a three-dimensional network structure.
2. A removable wax core for preparing hollow ceramics according to claim 1, characterized in that: The wax core comprises the following raw materials in parts by mass: 75-100 parts of wax slurry raw material; Additives 0 to 10 parts. 5 to 15 parts of filler.
3. A removable wax core for preparing hollow ceramics according to claim 1, characterized in that: The wax slurry raw materials include the following raw materials in parts by mass: Soft wax 5-95 parts; 2-30 parts of beeswax; 20-80 parts of No. 58 semi-refined paraffin or 5-80 parts of No. 56 fully refined paraffin.
4. A removable wax core for preparing hollow ceramics according to claim 1, characterized in that: The additives include the following raw materials in parts by mass: Polyethylene 0-1 part; 2-12 parts of stearic acid.
5. The removable wax core for preparing hollow ceramics according to claim 1, characterized in that: The filler includes graphite.
6. The removable wax core for preparing hollow ceramics according to claim 1, characterized in that: The skeleton comprises polyurethane cotton or sponge, wherein the density of the polyurethane cotton is 10 to 25 ppi.
7. A method for preparing hollow ceramics, characterized in that: The following steps are involved: Step 1: Weigh the raw materials of each component according to the ratio, stir and mix them with a double planetary mixer for 1-4 hours, add additives and fillers, and stir for 1-4 hours to obtain wax slurry; Step 2: pouring the wax slurry into the mold with the skeleton, removing the excess surface after cooling, and obtaining a wax core of the desired shape; Step 3: placing the wax core in a mold filled with ceramic powder, then continuing to cover the mold with ceramic powder, and dry pressing under a certain pressure to obtain a ceramic green body; Step 4: After the green body is dried, the wax is removed and then fired to obtain a hollow ceramic product.
8. The method for preparing hollow ceramics according to claim 7, characterized in that: In the step 3, the wax core is heated from 20° C. to 120° C. at a rate of 3° C. / h, and kept warm for 2 to 12 hours to discharge the wax.
9. The method for preparing a hollow ceramic according to claim 7, characterized in that: After the wax is removed in step 4, the product is placed in a kiln for firing at a temperature of 1000 to 1650° C. for a holding time of 2 to 24 hours, and then cooled naturally to obtain a hollow plate-shaped ceramic product.