A polychrome ceramic body, its preparation method and use

Abstract

The application provides a multi-color ceramic body and a preparation method and application thereof. The multi-color ceramic body comprises a first ceramic body and a second ceramic body with different colors. Raw materials of the first ceramic body and the second ceramic body comprise ceramic powder, organic monomers and a crosslinking agent. The organic monomers in the first ceramic body and the second ceramic body are crosslinked to form polymers. The multi-color ceramic provided by the application has high bonding strength between the bodies with different colors. The multi-color ceramic obtained by sintering the ceramic body has high structural stability and a long service life.

Description

Technical Field

[0001] This application relates to the field of ceramic materials technology, specifically to a multicolor ceramic green body, its preparation method, and its application. Background Technology

[0002] Ceramic combines the texture of metal with the luster of glass. When used to make casings for electronic devices such as mobile phones, ceramic casings offer advantages such as wear resistance, skin-friendliness, good impact resistance, and weak electromagnetic shielding. Multi-colored ceramics, referring to ceramic products with multiple colors, contribute to enriching the appearance of electronic devices when used as casings.

[0003] Currently, multicolor ceramics can be prepared using injection molding or slip casting. Injection molding is complex and expensive, and the resulting green bodies require a long debinding time, making them prone to deformation during this process. Slip casting, on the other hand, has a long production time, and the resulting green bodies have low strength. More importantly, both processes result in weak bonding between different colored green bodies, leading to easy deformation during sintering and low structural strength in the final ceramic parts, which is detrimental to the application of multicolor ceramics. Therefore, it is necessary to provide a new type of multicolor ceramic green body to prepare multicolor ceramics with higher structural reliability. Summary of the Invention

[0004] To address the aforementioned problems, this application provides a multi-colored ceramic green body with high bonding strength between the different colored green bodies. Multi-colored ceramics sintered from this green body exhibit high structural stability and a long service life. This application also provides a method for preparing the multi-colored ceramic green body, which has a short production cycle, is simple to operate, and is easily scalable for industrial production.

[0005] The first aspect of this application provides a multi-colored ceramic green body, including a first ceramic green body and a second ceramic green body with different colors. The raw materials of the first ceramic green body and the second ceramic green body include ceramic powder, organic monomers and crosslinking agents. The organic monomers in the first ceramic green body and the second ceramic green body are crosslinked to form a polymer.

[0006] In this application, the ceramic blocks of different colors in the multicolor ceramic body are connected by covalent bonds, thus having a high bonding strength. The multicolor ceramic body has good shape retention and is not easily deformed during sintering. The multicolor ceramic obtained by sintering has strong bonding force between ceramic blocks of different colors, clear color interface, and high overall structural stability, making it less prone to cracking.

[0007] Optionally, the first ceramic blank and the second ceramic blank form an integrated structure.

[0008] Optionally, the organic monomer includes one or more of acrylamide, methylbisacrylamide, and N-vinylpyrrolidine.

[0009] Optionally, the first ceramic body comprises the following components in the following mass percentages: 1% to 30% organic polymer, 50% to 90% ceramic powder, 1% to 5% first colorant, and 7% to 42% solvent; the second ceramic body comprises the following raw materials in the following mass percentages: 1% to 30% organic polymer, 50% to 90% ceramic powder, and 7% to 42% solvent.

[0010] Optionally, the second ceramic body further includes a second colorant with a mass percentage of 1% to 5%, the composition of which is different from that of the first colorant.

[0011] Optionally, the bonding strength between the first ceramic body and the second ceramic body is greater than or equal to 10 MPa.

[0012] Optionally, the four-point bending strength of the multicolor ceramic blank is greater than or equal to 20 MPa.

[0013] The second aspect of this application provides a method for preparing a multi-colored ceramic green body, comprising:

[0014] The first ceramic slurry is injected into a mold and semi-cured to obtain a semi-cured first ceramic slurry; the viscosity of the semi-cured first ceramic slurry is 10000 mpa·s to 40000 mpa·s.

[0015] A second ceramic slurry is injected into the semi-cured first ceramic slurry and cured to obtain a multi-colored ceramic green body.

[0016] Optionally, the first ceramic slurry comprises the following components in the following mass percentages: 50% to 90% ceramic powder, 1 wt% to 5 wt% first colorant, 1% to 20% organic monomer, 0.1% to 5% crosslinking agent, and 7% to 42% solvent.

[0017] Optionally, the second ceramic slurry comprises the following components in the following mass percentages: 50% to 90% ceramic powder, 1% to 20% organic monomer, 0.1% to 5% crosslinking agent, and 7% to 42% solvent.

[0018] Optionally, the second ceramic slurry further includes 1% to 5% of colorant, wherein the first colorant and the second colorant are different in color.

[0019] Optionally, the semi-curing temperature is 20℃~90℃, and the semi-curing time is 1min~10min.

[0020] Optionally, the first ceramic slurry and / or the second ceramic slurry may further include a catalyst with a mass percentage of 0.01% to 5%.

[0021] Optionally, the first ceramic slurry and / or the second ceramic slurry may further include an initiator with a mass percentage of 0.01% to 5%.

[0022] Optionally, the first ceramic slurry and / or the second ceramic slurry further include a dispersant with a mass percentage of 0.01% to 1%.

[0023] Optionally, the first ceramic slurry and / or the second ceramic slurry may further include a plasticizer at a mass percentage of 0.1% to 2%.

[0024] The method for preparing multicolor ceramic blanks provided in the second aspect of this application has a short production cycle and is easy to operate, making it suitable for industrial mass production.

[0025] Thirdly, this application provides a method for preparing multicolor ceramics, the method comprising: sintering a multicolor ceramic blank as described in the first aspect to obtain multicolor ceramics.

[0026] Optionally, the sintering temperature is 1000℃~1500℃, and the sintering heating rate is 0.01℃ / min~3℃ / min.

[0027] Optionally, the sintering adopts a gradient heating method, which includes: heating to a maximum of 600°C at a heating rate of 0.1°C / min to 1°C / min and holding at that temperature for 1h to 3h; and heating to a maximum of 1500°C at a heating rate of 1°C / min to 3°C / min and holding at that temperature for 1h to 3h.

[0028] Fourthly, this application provides a multicolor ceramic, which is prepared by the method for preparing multicolor ceramics as described in the third aspect.

[0029] Fifthly, this application provides an electronic device comprising the multicolor ceramic as described in the fourth aspect. Attached Figure Description

[0030] Figure 1 This is a flowchart illustrating the preparation process of a multicolor ceramic green body according to an embodiment of this application;

[0031] Figure 2 This is a schematic diagram of a crosslinking reaction provided in an embodiment of this application. Detailed Implementation

[0032] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0033] Currently, there are two methods for preparing two-color ceramics: two-color injection molding and slip casting. Two-color injection molding involves injecting granulated material into a first mold cavity using an injection molding machine, followed by a second injection of granulated material of a different color into a second mold cavity to obtain a two-color ceramic green body. Slip casting involves pouring in clay, removing excess clay, adjusting the mold humidity to absorb water from the clay, and then injecting clay of another color to obtain a two-color ceramic green body. However, two-color injection molding is more complex, requiring equipment such as granulators and injection molding machines, resulting in higher production costs. Furthermore, the degreasing time for injection-molded green bodies is long, making them prone to deformation. Slip casting has a long molding time and is not suitable for producing large ceramic parts. Most importantly, the different colored green bodies obtained by these two processes are bonded through physical action, resulting in weak interfacial bonding and making the green bodies prone to cracking. The resulting multi-color ceramics have poor stability after sintering. Therefore, this application provides a method for preparing multi-colored ceramic green bodies. The method prepares multi-colored ceramic green bodies by gel casting and achieves the connection between different colored ceramic green bodies through chemical cross-linking, thereby improving the interfacial bonding force between different colored green bodies and making the sintered multi-colored ceramics have good structural stability.

[0034] Please see Figure 1 , Figure 1 This is a flowchart illustrating the preparation process of a multi-colored ceramic green body according to an embodiment of this application. The method for preparing the multi-colored ceramic green body includes:

[0035] Step 100: Inject the first ceramic slurry into the mold and allow it to partially cure to obtain the partially cured first ceramic slurry;

[0036] Step 200: Inject the second ceramic slurry into the semi-cured first ceramic slurry and cure it to obtain a multi-colored ceramic green body.

[0037] In step 100 of this application, the first ceramic slurry comprises the following components in the following mass percentages: 50%–90% ceramic powder, 1 wt%–5 wt% first colorant, 1%–20% organic monomer, 0.1%–5% crosslinking agent, and 7%–42% solvent. In some embodiments, the solvent includes water, and the solid content of the first ceramic slurry is 50%–90%.

[0038] In some embodiments of this application, the ceramic powder includes one or more of zirconium oxide, alumina, and magnesium oxide. These ceramic powders possess excellent toughness, strength, and hardness, which is beneficial for forming multicolor ceramics with high structural strength. In this application, the mass percentage of ceramic powder in the first ceramic slurry can be, but is not limited to, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, or 90%. In some embodiments of this application, the average particle size of the ceramic powder is 100 nm to 1 μm. The average particle size of the ceramic powder can be, but is not limited to, 100 nm, 200 nm, 300 nm, 500 nm, 800 nm, or 1000 nm.

[0039] In some embodiments of this application, the organic monomer includes one or more of acrylamide, methylbisacrylamide, and N-vinylpyrrolidine. In some embodiments, the organic monomer has a mass percentage content of 2% to 15% in the first ceramic slurry. The specific mass percentage content of the organic monomer in the first ceramic slurry may be, but is not limited to, 1%, 3%, 5%, 8%, 10%, 13%, 15%, 18%, or 20%. The organic monomer can form a three-dimensional network structure under the action of the crosslinking agent. Controlling the content of the organic monomer is beneficial to fully disperse and fix the ceramic powder, so that the ceramic body has good structural stability. Furthermore, during the debinding process of the body, the organic matter is easily removed, and the shrinkage of the ceramic is not easily deformed. In some embodiments of this application, the crosslinking agent includes one or more of N,N-methylenebisacrylamide and polyethylene glycol dimethicone. The mass percentage of the crosslinking agent in the first ceramic slurry may be, but is not limited to, 0.1%, 0.3%, 0.5%, 0.8%, 1%, 2%, 3%, 4%, or 5%. The content of the crosslinking agent affects the length of the polymer chain formed by the organic monomers. Controlling the content of the crosslinking agent to 0.1% to 5% is beneficial for the organic monomers to crosslink and form a complete three-dimensional network structure, so that the ceramic green body has good structural stability and the ceramic powder can be uniformly dispersed in the ceramic green body.

[0040] In some embodiments of this application, the first ceramic slurry further includes an initiator at a mass percentage of 0.01% to 5%. The initiator can generate free radicals, which can initiate the polymerization reaction between the organic monomer and the crosslinking agent, accelerating gel curing. In some embodiments, the initiator includes one or more of persulfate and hydrogen peroxide. The mass percentage of the initiator in the first ceramic slurry may specifically be, but is not limited to, 0.01%, 0.05%, 0.1%, 0.5%, 1%, 3%, or 5%. In some embodiments of this application, the first ceramic slurry further includes a catalyst at a mass percentage of 0.01% to 5%. The catalyst can promote the decomposition of the initiator to generate free radicals, shortening the slurry curing time. In some embodiments, the catalyst includes one or more of tetramethylethylenediamine or dimethylaniline. The mass percentage of the catalyst in the first ceramic slurry may specifically be, but is not limited to, 0.01%, 0.05%, 0.1%, 0.5%, 1%, 3%, or 5%.

[0041] In some embodiments of this application, the first ceramic slurry further includes a dispersant at a mass percentage of 0.01% to 1%. The dispersant can inhibit the agglomeration of ceramic powder and improve the uniformity of the ceramic powder dispersion in the slurry. In some embodiments, the dispersant includes one or more of citrate, polyacrylic acid, tetramethylammonium hydroxide, and polymethyl methacrylate. The mass percentage of the dispersant in the first ceramic slurry may specifically be, but is not limited to, 0.01%, 0.05%, 0.1%, 0.5%, 0.8%, or 1%.

[0042] In some embodiments of this application, the first ceramic slurry further includes a plasticizer at a mass percentage of 0.01% to 2%. Adding a plasticizer helps improve the toughness of the green body, increases its moisture retention, and mitigates shrinkage and cracking problems during drying. In some embodiments, the plasticizer includes one or more of polyethylene glycol, glycerol, ethylene glycol, and polyvinylpyrrolidone. The mass percentage of the plasticizer in the first ceramic slurry may specifically be, but is not limited to, 0.01%, 0.05%, 0.1%, 0.5%, 0.8%, 1%, 1.5%, or 2%.

[0043] In this application, the specific composition of the colorant in the first ceramic slurry can be selected according to the desired color. In some embodiments, the colorant can be a transition metal compound such as chromium, manganese, iron, cobalt, nickel, copper, and zinc, or a lanthanide metal compound such as lanthanum, cerium, praseodymium, neodymium, samarium, and erbium. In some embodiments of this application, the average particle size of the colorant is 100 nm to 1 μm.

[0044] In some embodiments of this application, the first ceramic slurry comprises the following components in weight percentages: 50% to 90% ceramic powder, 2% to 15% organic monomer, 0.2% to 4% crosslinking agent, 0.05% to 0.5% dispersant, 0.5% to 1.5% plasticizer, 1% to 5% colorant, 0.01% to 2% catalyst, 0.01% to 2% initiator, and 7% to 42% solvent.

[0045] In some embodiments of this application, the preparation of the first ceramic slurry includes: mixing ceramic powder, crosslinking agent, dispersant, plasticizer, colorant, and solvent to obtain a mixture; ball milling the mixture; and then adding a catalyst and initiator to the mixture to obtain the first ceramic slurry. In this application, the viscosity of the first ceramic slurry is less than or equal to 1000 mPa·s.

[0046] In some embodiments of this application, after the first ceramic slurry is injected into the mold, it is semi-cured. The semi-curing temperature is 20℃ to 90℃, and the semi-curing time is 1 min to 10 min. Specifically, the semi-curing temperature can be, but is not limited to, 20℃, 30℃, 50℃, 80℃, or 90℃, and the semi-curing time can be, but is not limited to, 1 min, 3 min, 5 min, 8 min, or 10 min. In some embodiments, the semi-curing temperature is 20℃ to 80℃, and the semi-curing time is 2 min to 8 min. During the semi-curing process, organic monomers polymerize under the action of crosslinking agents, initiators, and catalysts to form polymers, and the liquid slurry gels and solidifies, with the viscosity of the slurry gradually increasing. For example, the viscosity of the first ceramic slurry before injection molding is 100 mPa·s; as the curing time increases, the viscosity of the first ceramic slurry gradually increases to 1000 mPa·s and then to 10000 mPa·s.

[0047] In this embodiment, when the first ceramic slurry is semi-cured, a second ceramic slurry is injected into the semi-cured first ceramic slurry. In this embodiment, the viscosity of the semi-cured first ceramic slurry is 10000 mPa·s to 40000 mPa·s. At this time, the first ceramic slurry is in a non-flowing or jelly-like state, and has basically set. The first ceramic slurry also contains some organic monomers and crosslinking agents, which can react with the organic monomers and crosslinking agents in the second ceramic slurry. This allows chemical bonds to be formed at the interface between different slurries, thereby improving the bonding force between green bodies of different colors. Moreover, within this viscosity range, the color interface between green bodies formed by different slurries is relatively clear, resulting in a good visual effect. In this application, the viscosity of the semi-cured first ceramic slurry may specifically be, but is not limited to, 10000 mPa·s, 13000 mPa·s, 15000 mPa·s, 18000 mPa·s, 20000 mPa·s, 25000 mPa·s, 30000 mPa·s, or 40000 mPa·s. In some embodiments, the viscosity of the semi-cured first ceramic slurry is 10000 mPa·s to 30000 mPa·s.

[0048] In some embodiments of this application, the second ceramic slurry comprises the following components in weight percentages: 50%–90% ceramic powder, 1%–20% organic monomer, 0.1%–5% crosslinking agent, and 7%–42% solvent. When the second ceramic slurry does not contain colorant, the ceramic obtained after sintering the green body formed therefrom is white. In some embodiments of this application, the second ceramic slurry further comprises 1%–5% colorant in weight percentage, and the specific composition of the colorant can be selected according to the desired color.

[0049] In the second ceramic slurry of this application, the content and specific types of ceramic powder, crosslinking agent, dispersant, plasticizer, solvent, colorant, catalyst, and initiator can be selected according to the relevant parameters of the first ceramic slurry mentioned above. The effects of these parameters have been explained previously and will not be repeated here. It should be noted that the compositions of the first and second ceramic slurries are different. On the one hand, the colors of the green bodies formed by the first and second ceramic slurries after sintering are different. For example, the first ceramic slurry contains cobalt oxide as a colorant, and it is blue after sintering, while the second ceramic slurry does not contain any colorant and it is white after sintering; or the colorant of the first ceramic slurry is cobalt oxide, while the second ceramic slurry uses a different colorant such as nickel oxide. On the other hand, the composition of the first and second ceramic slurries can be adjusted based on the shape of the finished ceramic and the application scenario. For example, the content of ceramic powder in the first ceramic slurry is 80%, and the content of ceramic powder in the second ceramic slurry is 83%. In some embodiments of this application, in order to ensure that the shrinkage rates of the green bodies formed by the first ceramic slurry and the second ceramic slurry are similar, the solid content of the first ceramic slurry and the second ceramic slurry can be controlled to be similar values. In some embodiments, the solid content of the first ceramic slurry and the second ceramic slurry is 70% to 85%.

[0050] In some embodiments of this application, the curing temperature of the second ceramic slurry is 20°C to 90°C, and the curing time is 10 min to 60 min. The curing temperature may be, but is not limited to, 20°C, 30°C, 50°C, 80°C or 90°C, and the curing time may be, but is not limited to, 10 min, 20 min, 30 min, 50 min or 60 min.

[0051] In this application, the first ceramic slurry, in its semi-cured state, still retains reactive organic monomers and crosslinking agents. During the curing process after the second ceramic slurry is injected, the organic monomers in the second slurry crosslink with those in the first slurry, forming polymer chains. This creates a crosslinked network between the first and second ceramic slurries. After curing, the resulting ceramic green body exhibits chemical bonds between different colored green bodies—covalent bonds formed by monomer crosslinking. This structure provides the multi-colored ceramic green body with excellent structural stability. Please refer to [link to relevant documentation]. Figure 2 , Figure 2 This is a schematic diagram of a crosslinking reaction provided in one embodiment of this application. Figure 2 In the process, the organic monomers between the first ceramic slurry and the second ceramic slurry undergo a cross-linking reaction to form polymer chains, thereby creating chemical bonds between the slurry interfaces.

[0052] In some embodiments of this application, the multi-colored ceramic green body has three or more colors. The preparation of the multi-colored ceramic green body can be carried out by first semi-curing the first color ceramic slurry, then injecting the second color ceramic slurry for semi-curing, then injecting the third color ceramic slurry for semi-curing, and finally fully curing after all the color ceramic slurries have been injected to obtain the multi-colored ceramic green body.

[0053] The method for preparing multi-colored ceramic blanks provided in this application has a short molding cycle, and ceramic green blanks can be obtained in 5 minutes to 2 hours. Compared with slip casting (three or four days), this greatly shortens the production time of the product. The method is also suitable for preparing ceramic parts with larger dimensions (such as 1m) and complex shapes. Moreover, the preparation method achieves the molding of ceramic blanks through slurry solidification and uses chemical cross-linking to achieve the connection between ceramic blanks of different colors, so that the blanks of different colors have high bonding force. The resulting multi-colored ceramic blanks have high structural reliability. The multi-colored ceramics obtained after sintering the multi-colored ceramic blanks have good structural stability, and the interfaces of different colored ceramic layers are clear, with good visual effects.

[0054] This application also provides a multicolored ceramic green body prepared by the above-described preparation method. The multicolored ceramic green body comprises a first ceramic green body formed by curing a first ceramic slurry and a second ceramic green body formed by curing a second ceramic slurry. The first and second ceramic green bodies have different colors and are seamlessly connected by covalent bonds. In this application, the first and second ceramic green bodies are cross-linked and bonded by organic monomers in the ceramic slurry. There are no other components between the first and second ceramic green bodies, and the connecting surfaces of the two green bodies are in direct contact, thus forming an integrated structure.

[0055] In some embodiments of this application, the bond strength between the first ceramic body and the second ceramic body is greater than or equal to 10 MPa. The specific bond strength between the first ceramic body and the second ceramic body may be, but is not limited to, 10 MPa, 11 MPa, 12 MPa, 13 MPa, 18 MPa, etc. In some embodiments of this application, the four-point bending strength of the multi-colored ceramic body is greater than or equal to 20 MPa. The specific four-point bending strength of the multi-colored ceramic body may be, but is not limited to, 20 MPa, 21 MPa, 22 MPa, 23 MPa, etc.

[0056] The multicolor ceramic green body provided in this application has different colored green blocks bonded together by covalent bonds. Furthermore, the multicolor ceramic green body with this structure has a short sintering time and low sintering cost, which is conducive to the promotion and use of multicolor ceramics.

[0057] This application also provides a method for preparing multicolor ceramics, which is obtained by sintering the multicolor ceramic green body of this application. In some embodiments of this application, the sintering temperature is 1000℃~1500℃, and the specific sintering temperature may be, but is not limited to, 1000℃, 1200℃, 1300℃ or 1500℃. In some embodiments of this application, the sintering heating rate is 0.01℃ / min~3℃ / min, and the specific sintering heating rate may be, but is not limited to, 0.01℃ / min, 0.05℃ / min, 0.08℃ / min, 0.1℃ / min, 0.5℃ / min, 0.8℃ / min, 1℃ / min, 2℃ / min or 3℃ / min. In some embodiments, the sintering heating rate is 0.02℃ / min~2℃ / min. In some embodiments of this application, the sintering process employs a gradient heating method. The temperature conditions for the gradient heating are as follows: within the temperature range of 25℃ to 600℃, the heating rate is 0.1℃ / min to 1℃ / min, and the holding time is 1h to 3h; within the temperature range of 600℃ to 1600℃, the heating rate is 1℃ / min to 3℃ / min, and the holding time is 1h to 3h. Controlling the heating rate during sintering helps to suppress the debinding cracking of the green body, thereby improving the structural stability of the multicolor ceramic.

[0058] This application also provides multicolor ceramics prepared by the above-described method, which have a variety of colors. In some embodiments of this application, the four-point bending strength of the multicolor ceramic is greater than or equal to 1000 MPa. The four-point bending strength of the multicolor ceramic may specifically be, but is not limited to, 1000 MPa, 1050 MPa, 1100 MPa, 1150 MPa, 1200 MPa, or 1250 MPa.

[0059] The embodiments of this application will be further described below through multiple examples.

[0060] Example 1

[0061] A method for preparing multicolor ceramics, comprising:

[0062] 1) Preparation of the first ceramic slurry:

[0063] A mixture of 83% zirconium oxide ceramic powder, 5% acrylamide, 1% N,N-methylenebisacrylamide, 0.2% polyacrylic acid, 0.5% polyvinylpyrrolidone, 2% colorant (cobalt oxide, zinc oxide, and alumina composite colorant), and water was ball-milled to obtain a mixture. Then, 0.5% tetramethylethylenediamine and 0.5% ammonium persulfate were added to the mixture to obtain a colored ceramic slurry.

[0064] 2) Preparation of the second ceramic slurry:

[0065] The following ingredients were ball-milled to form a mixture: 85% zirconium oxide ceramic powder, 5% acrylamide, 1% N,N-methylenebisacrylamide, 0.2% polyacrylic acid, 0.5% polyvinylpyrrolidone, and water. Then, 0.5% tetramethylethylenediamine and 0.5% ammonium persulfate were added to the mixture to obtain a white ceramic slurry.

[0066] 3) Preparation of multi-colored ceramic green bodies:

[0067] The first ceramic slurry was injected into the mold and cured at room temperature (25°C) for 5 minutes. The viscosity of the first ceramic slurry was 20,000 mPa·s. The first ceramic slurry was in a jelly-like state. The second ceramic slurry was injected into the mold and cured at room temperature (25°C) for 30 minutes. The resulting green body was then dried under the following conditions: first at 25°C for 24 hours, and then at 80°C for 12 hours, to obtain a multi-colored ceramic green body.

[0068] 4) Sintering:

[0069] Multicolor ceramic blanks were sintered using a gradient heating method. The specific temperature conditions were: 25℃~600℃, heating rate 0.5℃ / min, holding at 600℃ for 2h; 600℃~1450℃, heating rate 2℃ / min, holding at 1450℃ for 2h, to obtain multicolor ceramics.

[0070] Example 2

[0071] Example 2 uses the same first and second ceramic slurries as Example 1, the difference being that the multi-colored ceramic green body is prepared as follows in Example 2:

[0072] The first ceramic slurry was injected into the mold and cured at room temperature (25°C) for 15 minutes. The viscosity of the first ceramic slurry was 43000 mPa·s. The second ceramic slurry was then injected into the mold and cured at room temperature (25°C) for 30 minutes. The resulting green body was then dried under the following conditions: first at 25°C for 24 hours, and then at 80°C for 12 hours, to obtain a multi-colored ceramic green body.

[0073] The multicolor ceramic blank was sintered using the same method as in Example 1 to obtain multicolor ceramics.

[0074] Example 3

[0075] The difference between Example 3 and Example 1 lies in the sintering conditions of the multi-colored ceramic blank. The sintering conditions in Example 3 are as follows: the temperature is raised to 1450°C at a heating rate of 3°C / min and held for 2 hours to obtain multi-colored ceramic.

[0076] Comparative Example 1

[0077] A method for preparing multicolor ceramics (slip casting), comprising:

[0078] 1) Preparation of the first ceramic slurry:

[0079] A white ceramic slurry was obtained by ball milling 85% zirconium oxide ceramic powder, 4% polyvinyl alcohol (PVA), 0.5% ammonium persulfate, 0.1% n-octanol, and 10.4% water by weight.

[0080] 2) Preparation of the second ceramic slurry:

[0081] A black ceramic slurry was obtained by ball milling 83% zirconium oxide ceramic powder, 2% colorant (cobalt oxide, zinc oxide, and aluminum oxide composite colorant), 4% polyvinyl alcohol (PVA), 0.5% ammonium persulfate, 0.1% n-octanol, and 10.4% water.

[0082] 3) Preparation of multi-colored ceramic green bodies:

[0083] After slowly pouring the white ceramic slurry into the mold, wait 30 seconds and then pour off the excess slurry. Repeat this process several times to control the thickness of the green body at 1.5mm. Then slowly pour the black ceramic slurry into the mold, wait 30 seconds and then pour off the excess slurry. Repeat this process several times to control the thickness of the green body at 1.5mm. After air-drying for 3 days, the green body is demolded to obtain a multi-colored ceramic green body.

[0084] 4) Sintering:

[0085] Multicolor ceramic blanks were sintered using a gradient heating method. The specific temperature conditions were: 25℃~600℃, heating rate 0.5℃ / min, holding at 600℃ for 2h; 600℃~1450℃, heating rate 2℃ / min, holding at 1450℃ for 2h, to obtain multicolor ceramics.

[0086] Comparative Example 2

[0087] A method for preparing multicolor ceramics (injection molding), comprising:

[0088] 1) Preparation of the first ceramic slurry:

[0089] A white injection molding compound was prepared by mixing 85% zirconium oxide ceramic powder, 13% polyethylene binder, 1% stearic acid, and 1% polyethylene glycol 400 by weight percentage.

[0090] 2) Preparation of the second ceramic slurry:

[0091] Black injection molding compound was prepared by mixing 83% zirconium oxide ceramic powder, 2% colorant (cobalt oxide, zinc oxide, and aluminum oxide composite colorant), 13% polyvinyl alcohol (PVA), 1% stearic acid, and 1% polyethylene glycol 400 by weight.

[0092] 3) Preparation of multi-colored ceramic green bodies:

[0093] At 170℃, black material was injected at an injection speed of 20mm / s, and white material was injected under the same conditions. After holding at 70MPa for 5s and cooling, multi-colored ceramic blanks were obtained.

[0094] 4) Sintering:

[0095] Multicolor ceramic blanks were sintered using a gradient heating method. The specific temperature conditions were: 25℃~600℃, heating rate 0.1℃ / min, holding at 600℃ for 2h; 600℃~1450℃, heating rate 2℃ / min, holding at 1450℃ for 2h, to obtain multicolor ceramics.

[0096] Effect Example

[0097] To verify the performance of the multicolor ceramic green body prepared in this application, this application also provides effective examples.

[0098] (1) Mechanical properties of the multi-colored ceramic blanks of Examples 1-3 and Comparative Examples 1-2 were tested. The tests included four-point bending strength and bonding strength of ceramic blanks of different colors. The tests were conducted using a universal testing machine and the test standard was GBT6569-2006. Please refer to Table 1 for the test results.

[0099] Table 1 Mechanical properties of multicolor ceramic green bodies from various embodiments and comparative examples

[0100]

[0101]

[0102] As can be seen from Table 1, the ceramic green bodies prepared in the embodiments of this application have good structural stability and high bonding strength between ceramic green bodies of different colors. In each embodiment, during the preparation process of the ceramic green body in Example 2, the curing time of the first ceramic slurry is longer, the content of residual organic monomers in the slurry is lower, and the bonding force between the first ceramic slurry and the second ceramic slurry is relatively weaker.

[0103] (2) Mechanical properties of the multicolor ceramics in Examples 1-3 and Comparative Examples 1-2 were tested. The tests included four-point bending strength and bonding strength of ceramic blocks of different colors. The tests were conducted using a universal testing machine and the test standard was GBT 6569-2006. Please refer to Table 2 for the test results.

[0104] Table 2 Mechanical properties of multicolor ceramics in various embodiments and comparative examples

[0105] experimental group Four-point bending strength (MPa) Bond strength (MPa) Example 1 1100 320 Example 2 1040 300 Example 3 1050 305 Comparative Example 1 1000 280 Comparative Example 2 1020 290

[0106] As shown in Table 2, the multicolor ceramics prepared in the embodiments of this application have high structural strength, and the ceramic blanks of different colors are not prone to cracking. In various embodiments, the bonding force between the first ceramic slurry and the second ceramic slurry in the ceramic green body of Embodiment 2 is relatively weak, and bubbles are prone to appear at the interface during the firing process, resulting in slightly lower structural strength of the finished ceramic. The preparation method of Embodiment 3 adopts uniform heating, and there is a certain difference in shrinkage rate between the green bodies of different colors, resulting in slightly lower structural strength of the finished ceramic.

[0107] (3) Observe the multicolor ceramics of Examples 1-3 and Comparative Examples 1-2. Degreasing yield during the sintering process of the green body is judged by whether the ceramic cracks or deforms. Please refer to Table 3 for the test results.

[0108] Table 3 Degreasing yield of multicolor ceramic blanks in each embodiment and comparative example

[0109]

[0110]

[0111] As shown in Table 3, the multicolor ceramic green bodies prepared by the method of this application exhibit less deformation after sintering, which is beneficial for improving product yield. The preparation method in Example 3 uses uniform heating, resulting in a slightly lower degreasing yield; in the injection molding process of Comparative Example 2, the probability of green body drying deformation is high, leading to a lower product yield.

[0112] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of this patent should be determined by the appended claims.

Claims

1. A method for the production of a multi-coloured ceramic body, characterised in that, include: The first ceramic slurry is injected into the mold and semi-cured to obtain the semi-cured first ceramic slurry; The viscosity of the first ceramic slurry is less than or equal to 1000 mpa·s, and the viscosity of the semi-cured first ceramic slurry is 10000 mpa·s to 40000 mpa·s; the semi-curing temperature is 20℃ to 90℃, and the semi-curing time is 1 min to 10 min. A second ceramic slurry is injected into the semi-cured first ceramic slurry and cured to obtain a multi-colored ceramic green body; the curing temperature is 20℃~90℃ and the curing time is 10min~60min. The first ceramic slurry comprises the following components in weight percentage: 50%~90% ceramic powder, 1wt%~5wt% first colorant, 1%~20% organic monomer, 0.1%~5% crosslinking agent, 0.1%~2% plasticizer, and 7%~42% solvent; the second ceramic slurry comprises the following components in weight percentage: 50%~90% ceramic powder, 1%~20% organic monomer, 0.1%~5% crosslinking agent, 0.1%~2% plasticizer, and 7%~42% solvent.

2. The production method according to claim 1, wherein The first ceramic slurry and / or the second ceramic slurry further include a catalyst with a mass percentage of 0.01% to 5% and / or an initiator with a mass percentage of 0.01% to 5%.

3. The production method according to claim 1 or 2, characterized by, The first ceramic slurry and / or the second ceramic slurry further include a dispersant with a mass percentage of 0.01% to 1%.

4. A polychrome ceramic body obtainable by the process according to any one of claims 1 to 3, characterized in that, It includes a first ceramic body and a second ceramic body with different colors.

5. A multi-coloured ceramic body as claimed in claim 4, characterised in that, The bonding strength between the first ceramic preform and the second ceramic preform is greater than or equal to 10 MPa.

6. A method for producing a multi-color ceramic, characterized by, Multicolor ceramics are obtained by sintering the multicolor ceramic blank prepared by the method for preparing multicolor ceramic blanks as described in any one of claims 1-3 or the multicolor ceramic blank as described in any one of claims 4-5.

7. The method for preparing a multi-colored ceramic according to claim 6, wherein The sintering temperature is 1000℃~1500℃, and the sintering heating rate is 0.01℃ / min~3℃ / min.

8. The method for producing a multi-colored ceramic according to claim 6 or 7, wherein The sintering process employs a gradient heating method, which includes: heating to a maximum of 600°C at a heating rate of 0.1°C / min to 1°C / min and holding at that temperature for 1 hour to 3 hours; and heating to a maximum of 1500°C at a heating rate of 1°C / min to 3°C / min and holding at that temperature for 1 hour to 3 hours.

9. A polychrome ceramic, characterized in that, The multicolor ceramic is prepared by the method for preparing multicolor ceramic as described in any one of claims 6-8.

10. An electronic device, comprising: The electronic device includes the multicolor ceramic as described in claim 9.

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