Ceramic product and preparation method thereof

Abstract

The invention provides a ceramic product and a preparation method thereof. The preparation method comprises the steps that a 3D printing ceramic product adheres to a bottom plate, the periphery of the 3D printing ceramic product is sleeved with a rigid cylinder, and the bottom plate is fixed to the bottom of the rigid cylinder; filling refractory slurry; a top plate is fixed to the top of the rigid cylinder; degreasing and sintering the second primary product for the first time at the temperature of 500-1150 DEG C; and the wrapping ceramic primary product is cleaned, the rigid cylinder is taken away, the cleaned ceramic primary product is sintered for the second time at the temperature of 1000-1500 DEG C, so that the ceramic primary product is densified, and a finished product is obtained. The strength and compactness of a ceramic product can be further improved, and the problems of deformation, cracking, poor precision and the like in the sintering process are solved.

Description

Technical Field

[0001] The invention belongs to the technical field of ceramic product manufacturing, and specifically relates to a ceramic product and a preparation method thereof. Background Art

[0002] 3D printed ceramic products generally contain binders, most of which are organic binders. 3D printed ceramic products must be degreased and sintered to meet the performance requirements of ceramic products. The existing degreasing and sintering processes generally place the product in a ceramic bowl, fill the bowl with ceramic powder, and put it into a degreasing furnace and a sintering furnace for degreasing and sintering. Some do not use a bowl or fill powder, but directly put it into the furnace for degreasing and sintering. These degreasing and sintering processes take a long time, are prone to deformation and cracking, and have poor precision. Summary of the invention

[0003] In order to solve the above technical problems, the present invention provides a ceramic product and a preparation method thereof to solve the problems in the above background technology.

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

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

[0006] S2, adhering the 3D printed ceramic product to the bottom plate through the bracket, sleeve the rigid cylinder around the 3D printed ceramic product so that the 3D printed ceramic product is located at the center of the rigid cylinder, and fix the bottom plate to the bottom of the rigid cylinder;

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

[0008] S4, fixing the top plate on the top of the rigid cylinder to obtain a first primary product;

[0009] S5, autoclaving the first primary product to remove the top plate and the bottom plate to obtain a second primary product, and performing a first degreasing and sintering on the second primary product at a temperature of 500° C. to 1150° C. to obtain a ceramic primary finished product;

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

[0011] Compared with the prior art, the beneficial effects of the present application are as follows: in the present application, by filling refractory slurry between the 3D printed ceramic product and the rigid cylinder, and by including refractory materials and expansion agents in the raw materials of the refractory slurry, the expansion agent rapidly expands in volume during steam autoclaving, and forms isostatic pressure on the refractory material, so that the refractory material particles are tightly combined, and the refractory slurry is well combined with the rigid cylinder, 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 degreasing and sintering process. At the same time, the ceramic product preparation method provided by the present invention greatly shortens the production cycle. The ceramic preparation method of the present invention has a production cycle of 8 to 10 hours, while the traditional preparation method generally takes more than 20 hours. In addition, the present invention performs two degreasing 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 will not cause deformation, cracking, poor precision and other problems 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 expansion agent, 0.5 to 2 parts of wetting agent, and 0.05 to 0.15 parts of defoaming agent.

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

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

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

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

[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 injection molding 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 injection molding machine is 600 mmHg to 700 mmHg, and the stirring time is 10 min to 30 min.

[0019] Preferably, in step S5, the autoclave pressure is 0.2 MPa to 0.5 MPa, the autoclave temperature is 130° C. to 150° C., and the autoclave 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. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0022] Figure 1 A flow chart of a method for preparing a ceramic product provided by 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] Description of reference numerals:

[0025] 3D printed ceramic products 1 Rigid cylinder 2 Bracket 3 Base Plate 4 roof 5 Exhaust hole 6 Refractory slurry 7

[0026] The present invention will be further described below in conjunction with the accompanying drawings and the accompanying descriptions. DETAILED DESCRIPTION

[0027] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the 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", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside" and "outside" etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and 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 referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

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

[0030] In the embodiments of the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the embodiments of the present invention can be understood according to specific circumstances.

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

[0032] S1, providing a 3D printed ceramic product 1, a bottom plate 4, a bracket 3, a top plate 5 and a 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 as to suspend the 3D printed ceramic product 1 at the center of the rigid cylinder 2. The rigid cylinder 2 refers to a cylinder that completely covers the 3D printed ceramic product 1, and has openings at the top and bottom. The overall shape is cylindrical, cubic, trapezoidal or spherical, but not limited to this.

[0034] S2, adhering the 3D printed ceramic product 1 to the bottom plate 4 through the bracket 3, sleeve the rigid cylinder 2 on the periphery of the 3D printed ceramic product 1, so that the 3D printed ceramic product 1 is located at the center of the rigid cylinder 2, and fix the bottom plate 4 to the bottom of the rigid cylinder 2;

[0035] Specifically, the bottom plate 4 is made of acrylic resin or heat-resistant steel, and the rigid cylinder 2 is made of heat-resistant steel. In order to meet the temperature requirements during high-temperature roasting, the rigid cylinder in the present invention is made of high-temperature resistant heat-resistant steel. Preferably, the rigid cylinder 2 is made of heat-resistant steel. Heat-resistant steel has a low cost and its operating temperature can reach about 900°C to 1100°C, which can fully meet the process requirements of the present invention. Exemplarily, the heat-resistant steel can be made of 1Cr 17 Mo, 4Cr 25 Ni 35 Co 15 W5, CD-EDM650+HIP tungsten alloy, etc., but not limited to.

[0036] S3, filling 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, so 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, and in this step, the refractory slurry 7 is filled into the gap until the entire rigid cylinder 2 is filled;

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

[0039] In the present invention, the refractory slurry 7 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 expansion agent, 0.5 to 2 parts of wetting agent, and 0.05 to 0.15 parts of defoaming agent.

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

[0041] The refractory material is specifically magnesium oxide with a particle size of 180 mesh to 500 mesh. Magnesium oxide has a high refractory temperature and does not stick during high-temperature roasting. In addition, magnesium oxide has a large thermal expansion coefficient. It expands when heated after roasting, pouring, and pouring, and forms microcracks when cooled, so that it can be cleaned by simple mechanical methods (shot blasting, vibration, high-pressure water or air, etc.), which greatly simplifies the cleaning procedure of the ceramic outer coating layer. The particle size of magnesium oxide is 180 mesh to 500 mesh, and the expansion agent prevents the refractory layer from cracking and collapsing during the autoclaving process. At the same time, it can also ensure the tightness of the refractory slurry 7 and the 3D printed ceramic product 1, and is beneficial to the densification of 3D printed ceramic products and avoidance of cracking.

[0042] The expansion agent expands during the autoclaving process, so that the refractory material in the enclosed space is subjected to isostatic pressure, so that the refractory slurry 7 is densified and combined with the rigid cylinder 2 to improve the low-temperature strength of the ceramic product. The expansion agent can be selected from high-density polyethylene and polypropylene fibers, which will expand during the autoclaving process. Preferably, the expansion agent is selected from high-density polyethylene, whose molecular weight is 50,000 to 100,000, and whose linear expansion rate reaches 2000 to 2400×10 -7 / ℃, which is hundreds of times larger than the linear expansion rate of the refractory materials in the refractory slurry formula, can form a large compressive stress on the refractory materials during the autoclaving process, promoting the densification of the refractory materials. In addition, high-density polyethylene has low water absorption, and the refractory slurry requires less water; and high-density polyethylene is easily oxidized and removed during later roasting.

[0043] The dosage of organic expander is 0.1 to 1 part. When the dosage of expander is less than 0.1 part, it is difficult to promote the densification of the refractory body layer; when the dosage of expander is greater than 1 part, the pressure generated by autoclaving is too large, which can easily damage the investment mold. Preferably, the dosage of expander is 0.1 to 0.8 parts, more preferably 0.1 to 0.5 parts; exemplary ones are 0.1 parts, 0.15 parts, 0.2 parts, 0.3 parts, 0.4 parts, and 0.45 parts, but not limited to these. Inorganic expanders provide expansion force at high temperatures, maintain isostatic pressure at high temperatures, so that the shrinkage of the refractory layer formed by the sintering of the refractory material at high temperatures due to the partial sintering of the 3D ceramic product will not cause deformation and cracking, and is beneficial to the densification of the ceramic product.

[0044] The wetting agent promotes the combination of the expansion agent, the refractory material and the water to form a slurry with stable performance, so that the slurry can be cast. In addition, the wetting agent can also be completely eliminated during the high-temperature roasting process. The wetting agent can be selected from the wetting dispersant produced by Evonik Specialty Chemicals Co., Ltd., such as TEGO Dispers 755W, etc., but is not limited to this. The amount of the wetting agent is 0.5 to 2 parts, and exemplary ones are 0.6 parts, 0.8 parts, 1 part, 1.4 parts, 1.6 parts, and 1.9 parts, but is not limited to this.

[0045] The defoamer can eliminate the foam in the refractory slurry and improve the overall performance of the refractory slurry. The defoamer can also be completely eliminated during the high-temperature roasting process. Specifically, the defoamer can be a polyether defoamer, but is not limited to this. The amount of the defoamer is 0.05 to 0.15 parts, exemplarily 0.07 parts, 0.1 parts, 0.12 parts, and 0.14 parts, but is not limited to this.

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

[0047] Specifically, the top plate 5 and the rigid cylinder 2 are both provided with exhaust holes 6, the aperture of the exhaust holes 6 is 80μm to 150μm, and the exhaust holes 6 can be used as a channel for the discharge of water in the refractory slurry 7 during autoclaving; it can play a role in exhausting in the later sintering, ensuring that it has 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 seal the 3D printed ceramic product 1 in the first primary product composed of the three, so that the refractory slurry 7 is densified after being subjected to the expansion pressure of the expansion agent during the autoclaving process, and combined with the rigid cylinder 2. The top plate 5 can be made of ordinary steel. Correspondingly, the top plate 5 is also provided with an exhaust hole 6 that passes through the top plate, so that water vapor can be discharged from the pores during the autoclaving process, while the refractory slurry 7 cannot be discharged from the pores f.

[0048] S5, autoclaving the first primary product to remove the top plate and the bottom plate to obtain a second primary product, and performing a first degreasing and sintering on the second primary product at a temperature of 500° C. to 1150° C. to obtain a ceramic primary finished product;

[0049] Specifically, the first primary product is autoclaved in an autoclave using steam; during autoclaving, the autoclave pressure is 0.2MPa-0.5MPa, the autoclave temperature is 130°C-150°C, and the autoclave time is 10min-90min. Under this condition, the expansion agent can expand rapidly, making the refractory material dense. At the same time, under this condition, the moisture in the refractory layer will also be quickly removed. Removing moisture in the steam can effectively prevent the refractory layer formed after the refractory slurry 7 is roasted from cracking, ensuring that the refractory layer has a high low-temperature strength, and the ceramic primary product after the first degreasing and sintering has a low degree of sintering.

[0050] It should be noted that after the first degreasing and sintering of the refractory slurry 7, the organic matter in the refractory slurry 7 will be removed, so the refractory slurry 7 will form a refractory layer around the primary ceramic product after sintering, and the minimum thickness of the refractory layer formed after the refractory slurry 7 is ≥20mm; since the content of organic components in the refractory slurry 7 of the present invention is very low (≤5%), the thickness of the refractory layer has little effect on the oxidation of organic components, so the present invention can use a thicker refractory material layer. At the same time, since the thickness of the refractory material layer in the present invention is relatively large, if other heating methods (such as direct atmospheric pressure air heating) are used, it is easy to cause the surface moisture to be discharged too quickly, which may cause a large number of cracks, or even explosion defects. The present invention uses saturated steam to heat the drainage, which can help eliminate this defect.

[0051] S6, cleaning the periphery of the ceramic primary product, removing the rigid cylinder, and sintering the cleaned ceramic primary product for a second time at a temperature of 1000° C. to 1500° C. to densify the ceramic primary product to obtain a finished product;

[0052] Specifically, the ceramic primary product has a low degree of sintering due to the mineralizer and has a certain strength, while the refractory slurry around the ceramic primary product is relatively loose because it has not reached the sintering temperature. In this way, the ceramic powder around the ceramic primary product can be cleaned by high-pressure water (gas), and the cleaned ceramic primary product can be obtained. At the same time, in the actual use process, if the ceramic primary product does not require high strength and density, there is no need to carry out the second sintering process. If high strength and density are required, further sintering and densification must be carried out in a high-temperature furnace. At this stage, because the product has initial strength, deformation is greatly reduced. Therefore, compared with the first degreasing 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 can be obtained.

[0053] At the same time, since the anti-deformation ability of the 3D printed ceramic product 1 during the degreasing and sintering process mainly comes from the refractory layer formed by the rigid cylinder 2 and the refractory slurry 7, the refractory layer allows the 3D printed ceramic product 1 to maintain isotropic compressive stress, so that the 3D printed ceramic product 1 is degreased and sintered in the cavity formed by the refractory layer. Therefore, the refractory material can completely use MgO with a higher thermal expansion coefficient as the main refractory material. The microcracks generated by MgO during high-temperature degreasing, high-temperature sintering, and cooling processes greatly reduce the bonding strength between the refractory material and the 3D printed ceramic product 1, so that the shell can be removed by simple physical methods (shot blasting, vibration, sand blasting, high-pressure water spraying, ultrasonic wave), which greatly reduces the difficulty of removing the refractory material.

[0054] In addition, an expansion agent is introduced into the refractory slurry 7 of the present invention, and 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 densifying the refractory layer, ensuring that the 3D printed ceramic product 1 has sufficient low-temperature strength to meet production needs, while providing high-temperature isostatic pressure, which is beneficial to prevent high-temperature deformation, cracking and densification.

[0055] In summary, the ceramic product and preparation method thereof in the above-mentioned embodiments of the present invention, by filling the refractory slurry 7 between the 3D printed ceramic product 1 and the rigid cylinder 2, the raw materials of the refractory slurry 7 include refractory materials and expansion agents, the expansion agent expands rapidly in volume during steam autoclaving, and forms isostatic pressure on the refractory material, so that the refractory material particles are tightly combined, and the refractory slurry is well combined with 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 degreasing and sintering process. At the same time, the ceramic product preparation method provided by the present invention greatly shortens the production cycle. The production cycle of the ceramic preparation method of the present invention is 8 to 10 hours, while the traditional preparation method generally takes more than 20 hours. In addition, the present invention performs two degreasing 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 will not cause deformation, cracking, poor precision and other problems during the sintering process.

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

[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 an organic binder with metal powder to produce 3D printed metal products, and powder injection molded ceramic products using this process for degreasing and sintering should be included in the scope of protection of the present invention.

Claims

1. A method for preparing a ceramic product, characterized in that: include: S1. Provide 3D printed ceramic products, base plates, brackets, top plates and rigid cylinders with openings at both ends; S2, adhering the 3D printed ceramic product to the bottom plate through the bracket, sleeve the rigid cylinder around the 3D printed ceramic product so that the 3D printed ceramic product is located at the center of the rigid cylinder, and fix the bottom plate to the bottom of the rigid cylinder; S3, filling the gap between the 3D printed ceramic product and the rigid cylinder with refractory slurry; S4, fixing the top plate on the top of the rigid cylinder to obtain a first primary product; S5, autoclaving the first primary product to remove the top plate and the bottom plate to obtain a second primary product, and performing a first degreasing and sintering on the second primary product at a temperature of 500° C. to 1150° C. to obtain a ceramic primary finished product; S6. Clean the periphery of the ceramic primary product, remove the rigid cylinder, and sinter the cleaned ceramic primary product for a second time at a temperature of 1000° C. to 1500° C. to densify the ceramic primary product to obtain a finished product.

2. The method for preparing a ceramic product according to claim 1, characterized in that: 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 expansion agent, 0.5 to 2 parts of wetting agent, and 0.05 to 0.15 parts of defoaming agent.

3. The method for preparing a ceramic product according to claim 2, characterized in that: The refractory material is one or more of corundum, mullite, bauxite, silicon carbide, and magnesium oxide, and the expansion agent is plastic powder and / or plastic fiber.

4. The method for preparing a ceramic product according to claim 3, characterized in that: The refractory material is specifically magnesium oxide with a particle size of 180 mesh to 500 mesh.

5. The method for preparing a ceramic product according to claim 1, characterized in that: The top plate and the rigid cylinder are both provided with exhaust holes.

6. The method for preparing a ceramic product according to claim 5, characterized in that: The pore diameter of the exhaust through hole is 80 μm to 150 μm.

7. The method for preparing a ceramic product according to claim 1, characterized in that: The bottom plate is made of acrylic resin or heat-resistant steel, and the rigid cylinder is made of heat-resistant steel.

8. The method for preparing a ceramic product according to claim 1, characterized in that: In step S3, a vacuum injection molding 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 injection molding machine is 600 mmHg to 700 mmHg, and the stirring time is 10 min to 30 min.

9. The method for preparing a ceramic product according to claim 1, characterized in that: In step S5, the autoclave pressure is 0.2 MPa to 0.5 MPa, the autoclave temperature is 130° C. to 150° C., and the autoclave time is 10 min to 90 min.

10. A ceramic product, wherein the ceramic product is prepared by the ceramic product preparation method according to any one of claims 1 to 9.

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