A ceramic product and a method for producing the same

Abstract

The application provides a ceramic product and a preparation method thereof, which comprises the following steps: bonding a 3D printed ceramic product on a bottom plate, sleeving a rigid cylinder on the periphery of the 3D printed ceramic product, and fixing the bottom plate on the bottom of the rigid cylinder; filling refractory slurry; fixing a top plate on the top of the rigid cylinder; performing first debinding sintering on a second primary product at a temperature of 500-1150 DEG C; cleaning the wrapped ceramic primary product, taking away the rigid cylinder, and performing second sintering on the cleaned ceramic primary product at a temperature of 1000-1500 DEG C, so as to densify the ceramic primary product and obtain a finished product. The application performs two debinding sintering processes at different temperatures on the 3D printed ceramic product, so that the strength and density of the ceramic product can be further improved, and problems such as deformation, cracking, poor precision and the like do not occur in the sintering process.

Description

Technical Field

[0001] This invention belongs to the technical field of ceramic product manufacturing, and specifically relates to a ceramic product and its preparation method. Background Technology

[0002] 3D printed ceramic products generally contain binders, most of which are organic binders. 3D printed ceramic products must undergo debinding and sintering to meet the performance requirements of ceramic products. Existing debinding and sintering processes generally involve placing the product in a ceramic bowl, filling the bowl with ceramic powder, and then placing it in a debinding furnace and a sintering furnace for debinding and sintering. Some processes do not use bowls or powder fillers and directly place the product in the furnace for debinding and sintering. These debinding and sintering processes are time-consuming, prone to deformation and cracking, and have poor precision. Summary of the Invention

[0003] To address the aforementioned technical problems, this invention provides a ceramic product and its preparation method, thereby resolving the issues described in the background section.

[0004] On the one hand, the invention provides the following technical solution: a method for preparing a ceramic product, comprising:

[0005] S1. Provides 3D printed ceramic products, base plates, brackets, top plates, and rigid cylinders with openings at both ends;

[0006] S2. The 3D printed ceramic product is attached to the base plate by the bracket, and the rigid cylinder is sleeved around the 3D printed ceramic product so that the 3D printed ceramic product is in the center of the rigid cylinder. The base plate is fixed to the bottom of the rigid cylinder.

[0007] S3. Fill the gap between the 3D printed ceramic product and the rigid cylinder with refractory slurry;

[0008] S4. Fix the top plate to the top of the rigid cylinder to obtain the first primary product;

[0009] S5. The first primary product is steam-pressed to remove the top plate and the bottom plate to obtain the second primary product. The second primary product is then subjected to a first degreasing and sintering at a temperature of 500℃~1150℃ to obtain the primary ceramic product.

[0010] S6. Clean the periphery of the primary ceramic product and remove the rigid cylinder. Then, sinter the cleaned primary ceramic product a second time at a temperature of 1000℃~1500℃ to densify the primary ceramic product and obtain the finished product.

[0011] Compared with the prior art, the beneficial effects of this application are as follows: In this application, by filling the space between the 3D printed ceramic product and the rigid cylinder with refractory slurry, the raw materials of the refractory slurry include refractory materials and expanding agents. The expanding agent expands rapidly in volume during steam pressure, forming isostatic pressure on the refractory material, which makes the refractory material particles tightly bonded and also makes the refractory slurry and the rigid cylinder well bonded, giving the 3D printed ceramic product low-temperature strength. In addition, the outer rigid cylinder provides high-temperature strength for the 3D printed ceramic product, ensuring the smooth progress of the debinding and sintering process. At the same time, the ceramic product preparation method provided by this invention significantly shortens the production cycle. The ceramic preparation method of this invention has a production cycle of 8 to 10 hours, while the traditional preparation method generally takes more than 20 hours. Moreover, this invention performs two debinding and sintering processes at different temperatures on the 3D printed ceramic product, which can further improve the strength and density of the ceramic product and avoid problems such as deformation, cracking, and poor precision during the sintering process.

[0012] Preferably, the refractory slurry comprises the following components in parts by weight: 60 to 80 parts of refractory material, 15 to 25 parts of water, 0.1 to 1 part of expanding agent, 0.5 to 2 parts of wetting agent, and 0.05 to 0.15 parts of defoamer.

[0013] Preferably, the refractory material is one or more of corundum, mullite, bauxite, silicon carbide, and magnesium oxide, and the expanding agent is plastic powder and / or plastic fiber.

[0014] Preferably, the refractory material is magnesium oxide with a particle size of 180-500 mesh.

[0015] Preferably, both the top plate and the rigid cylinder are provided with exhaust vents.

[0016] Preferably, the diameter of the exhaust port is 80μm to 150μm.

[0017] Preferably, the base plate is made of acrylic resin or heat-resistant steel, and the rigid cylinder is made of heat-resistant steel.

[0018] Preferably, in step S3, a vacuum casting machine is used to fill the gap between the 3D printed ceramic product and the rigid cylinder with refractory slurry. The vacuum degree of the vacuum casting machine is 600 mmHg to 700 mmHg, and the stirring time is 10 min to 30 min.

[0019] Preferably, in step S5, the autoclaving pressure is 0.2 MPa to 0.5 MPa, the autoclaving temperature is 130°C to 150°C, and the autoclaving time is 10 min to 90 min.

[0020] On the other hand, the invention provides the following technical solution: a ceramic product, which is prepared by the above-mentioned ceramic product preparation method. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of the present invention, 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 of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 A flowchart of a ceramic product preparation method provided in an embodiment of the present invention;

[0023] Figure 2 A structural diagram of the first primary product provided in an embodiment of the present invention.

[0024] Explanation of reference numerals in the attached figures:

[0025] 3D printed ceramic products 1 Rigid cylinder 2 support 3 base plate 4 roof 5 Exhaust port 6 Refractory mortar 7

[0026] The present invention will be further described below with reference to the accompanying drawings and description. Detailed Implementation

[0027] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain embodiments of the present invention, and should not be construed as limiting the present invention.

[0028] In the description of the embodiments of the present invention, it should be understood that the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the embodiments of the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the present invention.

[0029] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of embodiments of the present invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0030] In the embodiments of the present invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of the present invention according to the specific circumstances.

[0031] In one embodiment of the present invention, such as Figure 1 As shown, a method for preparing a ceramic product includes:

[0032] S1. Provide 3D printed ceramic product 1, base plate 4, bracket 3, top plate 5, and rigid cylinder 2 with openings at both ends;

[0033] Specifically, the base plate 4 is used to bond and support the 3D printed ceramic product 1 so that the 3D printed ceramic product 1 is suspended in the center of the rigid cylinder 2. The rigid cylinder 2 refers to a cylinder that completely covers the 3D printed ceramic product 1. It has openings at the top and bottom. Its overall shape is cylindrical, cubic, trapezoidal or spherical, but is not limited to these.

[0034] S2. The 3D printed ceramic product 1 is attached to the base plate 4 by the bracket 3, and the rigid cylinder 2 is fitted around the 3D printed ceramic product 1 so that the 3D printed ceramic product 1 is in the center position of the rigid cylinder 2. The base plate 4 is fixed to the bottom of the rigid cylinder 2.

[0035] Specifically, the base plate 4 is made of acrylic resin or heat-resistant steel, and the rigid cylinder 2 is made of heat-resistant steel. To meet the temperature requirements during the high-temperature firing process, the rigid cylinder in this invention is made of high-temperature resistant steel. Preferably, the rigid cylinder 2 is made of heat-resistant steel, which has a lower cost and a working temperature of approximately 900℃ to 1100℃, fully meeting the process requirements of this invention. For example, 1Cr steel can be selected as the heat-resistant steel. 17 Mo, 4Cr 25 Ni 35 Co 15 W5, CD-EDM650+HIP tungsten alloy, etc., but not limited to these.

[0036] S3. Fill the gap between the 3D printed ceramic product 1 and the rigid cylinder 2 with refractory slurry 7;

[0037] Specifically, the size of the rigid cylinder 2 is larger than the size of the 3D printed ceramic product 1. Therefore, after the 3D printed ceramic product 1 is placed, a certain gap will be formed between the 3D printed ceramic product 1 and the rigid cylinder 2. In this step, refractory slurry 7 is filled into the gap until the entire rigid cylinder 2 is filled.

[0038] Furthermore, a vacuum casting machine is used to fill the gap between the 3D printed ceramic product 1 and the rigid cylinder 2 with refractory slurry 7. The vacuum degree of the vacuum casting machine is 600 mmHg to 700 mmHg, and the stirring time is 10 min to 30 min.

[0039] In this invention, the refractory slurry comprises the following components in parts by weight: 60 to 80 parts of refractory material, 15 to 25 parts of water, 0.1 to 1 part of expanding agent, 0.5 to 2 parts of wetting agent, and 0.05 to 0.15 parts of defoamer.

[0040] The refractory material is one or more of corundum, mullite, bauxite, silicon carbide, and magnesium oxide, and the expanding agent is plastic powder and / or plastic fiber.

[0041] The refractory material is specifically magnesium oxide with a particle size of 180-500 mesh. Magnesium oxide has a high refractory temperature and does not stick together during high-temperature firing. Furthermore, magnesium oxide has a large coefficient of thermal expansion, which causes it to expand when heated during firing, casting, and after casting. When cooled, it forms microcracks, which can be cleaned by simple mechanical methods (shot blasting, vibration, high-pressure water or air, etc.), greatly simplifying the cleaning process of the outer coating layer of the ceramic. Moreover, the particle size of magnesium oxide is 180-500 mesh, and the expansion agent prevents the refractory layer from cracking and collapsing during autoclaving. At the same time, it can also ensure the tight bonding between the refractory slurry 7 and the 3D printed ceramic product 1, and is conducive to the densification of the 3D printed ceramic product and the prevention of cracking.

[0042] The expanding agent expands during autoclaving, subjecting the refractory material in the sealed space to isostatic pressure. This densifies the refractory mortar 7 and bonds it to the rigid cylinder 2, improving the low-temperature strength of the ceramic product. The expanding agent can be high-density polyethylene or polypropylene fiber, both of which expand during autoclaving. Preferably, high-density polyethylene is used as the expanding agent, with a molecular weight of 50,000–100,000 and a linear expansion rate of 2000–2400 × 10⁻⁶. -7 At / ℃, the linear expansion rate is hundreds of times greater than that of the refractory materials in the refractory mortar formulation, which can generate greater compressive stress on the refractory materials during autoclaving, promoting the densification of the refractory materials. In addition, high-density polyethylene has low water absorption, resulting in a small water requirement for the refractory mortar; and high-density polyethylene is easily oxidized and removed during the later stage of calcination.

[0043] The amount of organic expanding agent is 0.1 to 1 part. When the amount of expanding agent is less than 0.1 part, it is difficult to promote the densification of the refractory body layer; when the amount of expanding agent is greater than 1 part, the pressure generated by autoclaving is too high, which can easily damage the investment mold. Preferably, the amount of expanding agent is 0.1 to 0.8 parts, more preferably 0.1 to 0.5 parts; exemplary amounts are 0.1 parts, 0.15 parts, 0.2 parts, 0.3 parts, 0.4 parts, and 0.45 parts, but are not limited thereto. Inorganic expanding agent provides expansion force at high temperatures, maintains isostatic pressure at high temperatures, and prevents deformation and cracking caused by the shrinkage of the refractory layer formed by the sintering of 3D ceramic products at high temperatures. At the same time, it is beneficial to the densification of ceramic products.

[0044] The wetting agent promotes the bonding of the expanding agent, refractory material, and water to form a stable slurry, which allows for casting and molding. Furthermore, the wetting agent can be completely eliminated during the high-temperature calcination process. The wetting agent can be a wetting and dispersing agent manufactured by Evonik Specialty Chemicals Ltd., such as TEGO Dispers 755W, but is not limited to this. The amount of wetting agent used is 0.5 to 2 parts, with examples of 0.6 parts, 0.8 parts, 1 part, 1.4 parts, 1.6 parts, and 1.9 parts, but is not limited to these amounts.

[0045] Defoamers can eliminate foam in refractory mortars, improving their overall performance. Defoamers can also completely eliminate foam during high-temperature calcination. Specifically, polyether-based defoamers can be used, but are not limited to this. The dosage of defoamer is 0.05–0.15 parts, exemplarily 0.07 parts, 0.1 parts, 0.12 parts, and 0.14 parts, but is not limited to these amounts.

[0046] like Figure 2 As shown, S4, the top plate 5 is fixed to the top of the rigid cylinder 2 to obtain the first primary product;

[0047] Specifically, both the top plate 5 and the rigid cylinder 2 are provided with vent holes 6. The vent holes 6 have a diameter of 80μm to 150μm. During autoclaving, the vent holes 6 can serve as channels for water to drain from the refractory slurry 7. During subsequent sintering, they can also play a role in venting, ensuring suitable air permeability during the sintering process. The top plate 5 is used to cooperate with the rigid cylinder 2 and the bottom plate 4 to enclose the 3D printed ceramic product 1 within the first primary product composed of the three. This allows the refractory slurry 7 to become dense after being subjected to the expansion pressure of the expanding agent during autoclaving and to bond with the rigid cylinder 2. The top plate 5 can be made of ordinary steel. Correspondingly, the top plate 5 is also provided with vent holes 6 that penetrate the top plate, so that water vapor can be discharged from the pores during autoclaving, while the refractory slurry 7 cannot be discharged from these pores.

[0048] S5. The first primary product is steam-pressed to remove the top plate and the bottom plate to obtain the second primary product. The second primary product is then subjected to a first degreasing and sintering at a temperature of 500℃~1150℃ to obtain the primary ceramic product.

[0049] Specifically, the first primary product is steam-pressed in an autoclave. During autoclaving, the pressure is 0.2 MPa to 0.5 MPa, the temperature is 130°C to 150°C, and the time is 10 to 90 minutes. Under these conditions, the expanding agent expands rapidly, densifying the refractory material. Simultaneously, moisture in the refractory layer is quickly removed. Removing moisture in the steam effectively prevents cracking of the refractory layer formed after firing the refractory slurry 7, ensuring high low-temperature strength. Furthermore, the primary ceramic product after the first debinding and sintering exhibits a lower degree of sintering.

[0050] It should be noted that after the first debinding and sintering of the refractory slurry 7, the organic matter in the refractory slurry 7 is removed. Therefore, after sintering, the refractory slurry 7 forms a refractory layer around the primary ceramic product. The minimum thickness of the refractory layer formed after firing the refractory slurry 7 is ≥20mm. Since the organic content in the refractory slurry 7 of this invention is very low (≤5%), the thickness of the refractory layer has little impact on the oxidation of organic components. Therefore, this invention can use a thicker refractory material layer. However, due to the large thickness of the refractory material layer in this invention, if other heating methods are used (such as direct atmospheric pressure air heating), the surface moisture may be drained too quickly, potentially causing numerous cracks or even explosions. This invention uses saturated steam heating for drainage, which helps to eliminate this defect.

[0051] S6. Clean the periphery of the primary ceramic product and remove the rigid cylinder. Then, sinter the cleaned primary ceramic product a second time at a temperature of 1000℃~1500℃ to densify the primary ceramic product and obtain the finished product.

[0052] Specifically, the primary ceramic product, due to the mineralizing agent, has undergone a relatively low degree of sintering and possesses a certain strength. However, the refractory slurry surrounding the primary ceramic product is relatively loose because it has not reached the sintering temperature. Thus, the ceramic powder surrounding the primary ceramic product can be cleaned using high-pressure water (or air) to obtain the cleaned primary ceramic product. In actual use, if the primary ceramic product does not require high strength and density, a second sintering process is unnecessary. If high strength and density are required, further sintering and densification in a high-temperature furnace is necessary. At this stage, because the product has acquired initial strength, deformation is greatly reduced. Therefore, compared to the first debinding and sintering process, the temperature of the second sintering needs to be increased to improve the density and strength of the ceramic product surface. After the second sintering, the finished ceramic product is obtained.

[0053] Meanwhile, since the deformation resistance of the 3D printed ceramic product 1 during the debinding and sintering process mainly comes from the refractory layer formed by the rigid cylinder 2 and the refractory slurry 7, the refractory layer maintains the compressive stress in all directions of the 3D printed ceramic product 1, allowing the 3D printed ceramic product 1 to be debinded and sintered in the cavity formed by the refractory layer. Therefore, MgO, which has a high coefficient of thermal expansion, can be used as the main refractory material. The microcracks generated by MgO during the high-temperature debinding, high-temperature sintering, and cooling process significantly reduce the bonding strength between the refractory material and the 3D printed ceramic product 1, allowing the shell to be removed by simple physical methods (shot blasting, vibration, sandblasting, high-pressure water spraying, and ultrasonic waves), greatly reducing the difficulty of removing the refractory material.

[0054] In addition, an expansion agent is introduced into the refractory slurry 7 of the present invention. Its expansion rate during high-temperature autoclaving is much greater than that of the refractory material, so that the refractory material powder is subjected to low-temperature isostatic pressure, thereby making the refractory layer denser. This ensures that the 3D printed ceramic product 1 has sufficient low-temperature strength to meet production requirements, while providing high-temperature isostatic pressure, which is beneficial to prevent high-temperature deformation cracking and densification.

[0055] In summary, the ceramic product and its preparation method in the above embodiments of the present invention, by filling the space between the 3D printed ceramic product 1 and the rigid cylinder 2 with refractory slurry 7, the refractory slurry 7, whose raw materials include refractory materials and expanding agents, allows the expanding agent to expand rapidly in volume during steam pressure, forming isostatic pressure on the refractory materials. This results in a tight bond between the refractory material particles and a good bond between the refractory slurry and the rigid cylinder 2, giving the 3D printed ceramic product low-temperature strength. In addition, the outer rigid cylinder 2 provides high-temperature strength for the 3D printed ceramic product 1, ensuring the smooth progress of the debinding and sintering process. At the same time, the ceramic product preparation method provided by the present invention significantly shortens the production cycle. The production cycle of the ceramic product preparation method of the present invention is 8-10 hours, while the traditional preparation method generally takes more than 20 hours. Furthermore, the present invention performs two debinding and sintering processes at different temperatures on the 3D printed ceramic product, which can further improve the strength and density of the ceramic product and prevent problems such as deformation, cracking, and poor precision during the sintering process.

[0056] In another embodiment of the present invention, a ceramic product is provided, which is prepared by the ceramic product preparation method described in the above embodiments.

[0057] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention, such as replacing the 3D printed ceramic material containing organic binder with metal powder to produce 3D printed metal products, or using this process to debind and sinter powder injection molded ceramic products, should be included within the scope of protection of the present invention.

Claims

1. A method for producing a ceramic product, characterized by, The application relates to a ceramic product preparation method. S1, providing a 3D-printed ceramic product, a bottom plate, a support, a top plate and a rigid cylinder with two open ends; S2, bonding the 3D-printed ceramic product on the bottom plate through the support, sleeving the rigid cylinder on the periphery of the 3D-printed ceramic product so that the 3D-printed ceramic product is located at the center position of the rigid cylinder, and fixing the bottom plate at the bottom of the rigid cylinder; S3, filling fire-resistant slurry into the gap between the 3D-printed ceramic product and the rigid cylinder; S4, fixing the top plate at the top of the rigid cylinder to obtain a first primary product; S5, performing steam pressure treatment on the first primary product, removing the top plate and the bottom plate to obtain a second primary product, and performing first degreasing sintering on the second primary product at a temperature of 500 DEG C to 1150 DEG C to obtain a ceramic primary product, wherein the fire-resistant slurry forms a fire-resistant layer on the periphery of the ceramic primary product after the first degreasing sintering; S6, cleaning the fire-resistant layer on the periphery of the ceramic primary product, and performing second sintering on the cleaned ceramic primary product at a temperature of 1000 DEG C to 1500 DEG C to densify the surface of the ceramic primary product to obtain a ceramic product; The fire-resistant slurry comprises the following components in parts by weight: 60 to 80 parts of fire-resistant material, 15 to 25 parts of water, 0.1 to 1 part of expanding agent, 0.5 to 2 parts of wetting agent and 0.05 to 0.15 part of defoaming agent. The fire-resistant material is one or more of corundum, mullite, bauxite, silicon carbide and magnesium oxide, and the expanding agent is plastic powder and / or plastic fiber.

2. The method for producing a ceramic product according to claim 1, characterized by, The fire-resistant material is specifically magnesium oxide with a particle size of 180 to 500 mesh.

3. The method of claim 1, wherein The top plate and the rigid cylinder are both provided with exhaust through holes.

4. The method for producing a ceramic product according to claim 3, characterized by The exhaust through holes have a pore diameter of 80 to 150 microns.

5. The method of claim 1, wherein The bottom plate is made of acrylic resin or heat-resistant steel, and the rigid cylinder is made of heat-resistant steel.

6. The method of claim 1, wherein In step S3, the fire-resistant slurry is filled into the gap between the 3D-printed ceramic product and the rigid cylinder by using a vacuum injection machine, the vacuum degree of the vacuum injection machine is 600 to 700 mmHg, and the stirring time is 10 to 30 minutes.

7. The method of claim 1, wherein In step S5, the steam pressure is 0.2 to 0.5 MPa, the steam pressure temperature is 130 to 150 DEG C, and the steam pressure time is 10 to 90 minutes.

8. A ceramic product prepared by the ceramic product preparation method in any one of claims 1 to 7.

Images