阅读说明：本技术 一种陶瓷浆料的制备方法及固形方法 (Preparation method and shaping method of ceramic slurry ) 是由 黎兆早 余恺为 吴明洋 于 2021-08-11 设计创作，主要内容包括：本发明公开了一种陶瓷浆料的制备方法及固形方法。包括以下步骤：将氧化物混合球磨,加入光敏树脂和助剂搅拌混合,加入陶瓷粉体搅拌均质化,得到固含量大于50％的陶瓷浆料。并利用光固化3D打印机,将陶瓷浆料应用于制备精度高、表面质量优的陶瓷制品。有益效果：通过优化陶瓷浆料的组成和配比,在不提高紫外曝光强度的情况下,完成表面快速固形,实现高固相材料的光固化3D打印。脱脂过程中,引入紫外再固化工艺,实现了保形脱脂效果,避免了陶瓷生坯在传统脱脂过程中应力变化引起的塌陷、裂痕等问题。脱脂过程中,引入光催化脱脂技术,进一步完成有机物的分解,实现完全脱脂,减少脱脂时间。实现陶瓷生坯固相含量超过90％的工艺水平。(The invention discloses a preparation method and a shaping method of ceramic slurry. The method comprises the following steps: mixing and ball-milling the oxides, adding the photosensitive resin and the auxiliary agent, stirring and mixing, adding the ceramic powder, stirring and homogenizing to obtain the ceramic slurry with the solid content of more than 50 percent. And the ceramic slurry is applied to the preparation of ceramic products with high precision and excellent surface quality by using a photocuring 3D printer. Has the advantages that: by optimizing the composition and the proportion of the ceramic slurry, the surface is quickly solidified under the condition of not improving the ultraviolet exposure intensity, and the photocuring 3D printing of high-solid-phase materials is realized. In the degreasing process, an ultraviolet re-curing process is introduced, so that the shape-preserving degreasing effect is realized, and the problems of collapse, cracks and the like caused by stress change in the traditional degreasing process of the ceramic green body are avoided. In the degreasing process, a photocatalytic degreasing technology is introduced to further finish the decomposition of organic matters, complete degreasing is realized, and the degreasing time is shortened. The technological level that the solid content of the ceramic green body exceeds 90 percent is realized.)

1. A preparation method of ceramic slurry is characterized by comprising the following steps: the method comprises the following steps: mixing and ball-milling the oxides, adding the photosensitive resin and the auxiliary agent, stirring and mixing, adding the ceramic powder, stirring and homogenizing to obtain the ceramic slurry with the solid content of more than 50 percent.

2. The method for preparing a ceramic slurry according to claim 1, wherein: the oxide is oxide A and oxideMixtures of substance B; the oxide A is SiO₂、Al₂O₃、ZrO₂One or more of CaO and MgO; the oxide B is TiO₂Or surface-modified TiO₂。

3. The method for preparing a ceramic slurry according to claim 1, wherein: the photosensitive resin is aldehyde photosensitive resin.

4. The method for preparing a ceramic slurry according to claim 1, wherein: the spectral transmittance of the ceramic powder under UVA is higher than 50%.

5. The method for preparing a ceramic slurry according to claim 1, wherein: the raw materials of the ceramic slurry comprise the following components: 50-85 vol% of ceramic powder, 10-45 vol% of photosensitive resin, 1-4 vol% of oxide and 1-4 vol% of auxiliary agent; the auxiliary agent is one or two of a dispersing agent and a surfactant.

6. The method for preparing a ceramic slurry according to claim 1, wherein: the particle size of the ceramic powder is 100-500 nm; the ceramic powder is one or more of oxide ceramic powder, nitride ceramic powder, carbide ceramic powder and titanate ceramic powder.

7. The method for preparing a ceramic slurry according to claim 2, wherein: the particle size of the oxide A is smaller than that of the oxide B; the particle size of the oxide A is 5-20 nm; the particle size of the oxide B is 15-40 nm.

8. A method for solidifying ceramic slurry is characterized in that: printing the ceramic slurry of any one of claims 1 to 7 layer by layer through a photocuring 3D printer, and forming to obtain a ceramic green body; transferring the mixture into a glue removing furnace in inert atmosphere, and degreasing the mixture under the irradiation of an ultraviolet lamp; drying, transferring to a sintering furnace in vacuum or inert gas, and sintering at controlled temperature to obtain the ceramic product.

9. The method for solidifying a ceramic slurry according to claim 8, wherein: the photocuring 3D printer is of an SLA type or a DLP type, and the photocuring wavelength is 300-400 nm; during the layer-by-layer printing, the thickness of each layer is 1-20 μm; the wavelength of the ultraviolet lamp is 300-400 nm.

10. The method for solidifying a ceramic slurry according to claim 8, wherein: the degreasing is thermal degreasing or catalytic degreasing; the conditions of the thermal degreasing are as follows: heating to 300-800 ℃ at a heating rate of 0.5-10 ℃/min; in the process, the temperature is kept for 0.5 to 3 hours at the temperature of 100 to 300 ℃ per liter; the catalytic degreasing conditions are as follows: setting the temperature to be 100-200 ℃ under the action of an acid catalyst.

Technical Field

The invention relates to the technical field of ceramics, in particular to a preparation method and a shaping method of ceramic slurry.

Background

The ceramic material is a three-major solid material at present because of its excellent properties of high hardness, high wear resistance, high temperature resistance, oxidation resistance, corrosion resistance, good chemical stability and the like. However, the ceramic material has the characteristics of extremely high hardness, large brittleness and the like, so that the ceramic material has the problems of high cost, low processing efficiency and the like in mechanical processing; and further, the application and development of ceramic products with complex structures are greatly limited by the traditional forming process.

In recent years, the rapid forming process based on ceramic products has become a hot research because of the advantages of no need of moulds, short manufacturing period, low cost and the like. Currently, the rapid prototyping process mainly includes SLS (selective laser sintering), FDM (fused deposition modeling), LOM (laminated solid manufacturing), I-J3 DP (three-dimensional inkjet printing), SLA (stereolithography), DLP (digital light processing). The SLS can prepare ceramic parts with complex structures without support, but has the defects that the density of the prepared ceramic body is low and needs to be improved by an impregnation process; FDM can realize complete bonding between layers, but has the difficulty of manufacturing ceramic filaments and controlling the dimensional precision of a micro structure in a forming process; LOM speed is fast, the cost is low, can make the large-scale ceramic part, but its disadvantage lies in that the forming accuracy is lower, the material utilization rate is low; the I-J3 DP can be used for manufacturing large-size samples without support, but has the defects that the solid phase content of ceramic slurry is low in the process, so that the ceramic product has poor compactness and low precision, and ceramic biscuit cracks or deforms easily in the sintering process. The SLA and DLP photocuring forming process has high forming precision, excellent surface quality and capacity of making parts with complicated structure, and is widely applied in aerospace, machinery, electronic communication, medical treatment and other fields.

The SLA and DLP photocuring and forming process of the ceramic product is similar to the photocuring process of photosensitive resin, and the difference is that the viscosity of the system is increased due to the addition of ceramic powder in ceramic slurry used by the ceramic product, so that the photocuring process engineering becomes more complicated. Meanwhile, the concentration of the photosensitive organic material in the ceramic slurry is far higher than that of the slurry used in the traditional mechanical forming process, so that the ceramic biscuit after photocuring forming needs longer degreasing time; the shrinkage rate of the sintered ceramic product is much higher than that of the product produced by the traditional mechanical forming process, and the product is easy to crack or deform, which is not beneficial to the manufacture of ceramic electronic devices such as precise MLCC and the like.

In conclusion, the ceramic slurry obtained by solving the problems has important significance for preparing ceramic products with high solid shape preparation precision and excellent surface quality.

Disclosure of Invention

The present invention is directed to a method for preparing ceramic slurry and a method for solidifying the ceramic slurry, so as to solve the problems of the background art.

In order to solve the technical problems, the invention provides the following technical scheme:

a preparation method of ceramic slurry comprises the following steps: mixing and ball-milling the oxides, adding the photosensitive resin and the auxiliary agent, stirring and mixing, adding the ceramic powder, stirring and homogenizing to obtain the ceramic slurry with the solid content of more than 50 percent. Wherein the optimal solid content is 80-85%.

Preferably, the oxide is a mixture of oxide A and oxide B; the oxide A is SiO₂、Al₂O₃、ZrO₂One or more of CaO and MgO; the oxide B is TiO₂Or surface-modified TiO₂. Wherein, the optimized proposal is the TiO modified by the surface of the silicon dioxide₂. Rayleigh scattering effect is generated between oxide A and oxide B。

Preferably, the photosensitive resin is an aldehyde photosensitive resin. The aldehyde photosensitive resin includes aldehyde resin, urea resin, and the like.

Preferably, the spectral transmittance of the ceramic powder under UVA conditions is higher than 50%.

Preferably, the raw materials of the ceramic slurry comprise the following components: 50-85 vol% of ceramic powder, 10-45 vol% of photosensitive resin, 1-4 vol% of oxide and 1-4 vol% of auxiliary agent; the auxiliary agent is one or two of a dispersing agent and a surfactant.

Optimally, the particle size of the ceramic powder is 100-500 nm; the ceramic powder is one or more of oxide ceramic powder, nitride ceramic powder, carbide ceramic powder and titanate ceramic powder. Wherein, the more optimized selection is alkali metal titanate and Al₂O₃And high-transmittance materials.

Preferably, the particle size of the oxide A is smaller than that of the oxide B; the particle size of the oxide A is 5-20 nm; the particle size of the oxide B is 15-40 nm.

Optimally, the method for solidifying the ceramic slurry comprises the steps of printing the ceramic slurry layer by layer through a photocuring 3D printer, and forming to obtain a ceramic green body; transferring the mixture into a glue removing furnace in inert atmosphere, and degreasing the mixture under the irradiation of an ultraviolet lamp; drying, transferring to a sintering furnace in vacuum or inert gas, and sintering at controlled temperature to obtain the ceramic product.

Optimally, the photocuring 3D printer is of an SLA type or a DLP type, and the photocuring wavelength is 300-400 nm; during the layer-by-layer printing, the thickness of each layer is 1-20 μm; the wavelength of the ultraviolet lamp is 300-400 nm.

Preferably, the degreasing is thermal degreasing or catalytic degreasing; the conditions of the thermal degreasing are as follows: heating to 300-800 ℃ at a heating rate of 0.5-10 ℃/min; in the process, the temperature is kept for 0.5 to 3 hours when the temperature per liter is 100 to 300 ℃; the catalytic degreasing conditions are as follows: the temperature is set to less than 200 ℃ under an acid catalyst.

According to the technical scheme, ceramic slurry is provided, ceramic powder with a proper particle size is selected to match aldehyde photosensitive resin to serve as a ceramic slurry main body, an oxidant is used as an auxiliary, and an auxiliary agent is selectively added to form ceramic slurry with high solid content and low viscosity; and the ceramic slurry is applied to the preparation of ceramic products with high density, high precision and excellent surface quality by using a photocuring 3D printer.

In the preparation method of the ceramic slurry, (1) the problem of low solid content in the traditional ultraviolet curing ceramic slurry is solved by utilizing the Rayleigh scattering effect generated between the oxidant A and the oxidant B with photocatalytic performance; the light curing molding process is accelerated, and the surface shaping time is shortened; accelerating the degreasing process, and decomposing organic macromolecules in the degreasing process into micromolecule CO₂And H₂O, organic micromolecule residues in the ceramic product are avoided; and the stability of the sintered crystal is enhanced by utilizing the compatibility among the oxidant A, the oxidant B and the ceramic powder. (2) The photosensitive resin adopts aldehyde resin, because the resin only generates formaldehyde gas in the degreasing process, and the formaldehyde gas is decomposed into CO by the photocatalysis of the oxidant₂And H₂And O, the generation of other high molecular impurities is avoided, so that the ceramic product with excellent quality is produced. (3) The ceramic powder with the light transmittance higher than 50% is beneficial to reducing the preparation time of the ceramic product and enhancing the quality of the ceramic product. (4) And (3) layered printing, namely refining the grain boundary by improving the curing quality of each layer, and improving the quality of the device.

In the solid-forming method of the ceramic slurry, (1) the photocuring stage: and printing layer by adopting an SLA type or DLP type photocuring 3D printer to obtain a ceramic green body. In the process, the transmittance of the ceramic slurry is lower than that of the traditional ultraviolet curing slurry due to high solid-phase content of the ceramic slurry, so that two-side or one-side exposure is adopted in the printing process, and the Rayleigh scattering effect is utilized to quickly solidify the surface; meanwhile, when the printing thickness of each layer is more than 1 μm, the central curing degree is weak, if ultraviolet exposure curing is continued, the surface photosensitive resin may receive excessive ultraviolet photon energy, and the conditions of deformation, black edges and the like occur, and simultaneously, the bonding stress between high polymer materials changes, so that the shape retention rate trend of the device is bad, and therefore, the ceramic green body obtained in the process is in a surface full-cured state and a central semi-cured state. (2) Degreasing stageSection (2): and post-curing and degreasing are carried out simultaneously, and when the surface full-cured organic matter is removed during degreasing, the central semi-cured part is cured under the irradiation of an ultraviolet lamp, so that the solid-forming problem of the degreasing stage of the device is further guaranteed. Meanwhile, a thermal degreasing or catalytic degreasing technology under the irradiation of an ultraviolet light source is adopted. Wherein, the irradiation intensity of the ultraviolet light source irradiating the surface of the ceramic green body is less than the energy of ultraviolet curing forming, and the irradiation intensity of the ultraviolet light is 40-60% of the irradiation intensity of photocuring. Due to the fact that post-curing is carried out and the ultraviolet light source completely cures the photosensitive resin with the semi-solid center, the ceramic green body is guaranteed not to collapse, crack and the like caused by stress change. In addition, first: due to the photocatalytic capacity of the oxidant in the ceramic green body, compared with the traditional degreasing process, the degreasing efficiency is further improved, and the solid phase ratio is improved. Secondly, the method comprises the following steps: the oxide is combined with aldehyde photosensitive resin, so that only CO is generated in the degreasing process₂And H₂And O, compared with the traditional degreasing process, the method avoids other high molecular substances from being attached to the surface of the ceramic powder, so that the degreasing degree of the ceramic green body is close to an ideal value, and the pollution defect caused by organic matters is avoided when the ceramic green body is sintered. Thirdly, the method comprises the following steps: the oxidant is used as a reinforcer and is coated on the surface of the main body and in the gaps of the large-particle-size ceramic powder, so that the filling of gaps and the consolidation of the large-particle-size powder are completed during sintering, the crystal regrowth of the ceramic powder is prevented, and the surface flatness of the ceramic device is ensured.

In summary, compared with the prior art, the invention has the following beneficial effects: (1) by optimizing the composition and the proportion of the ceramic slurry, the surface is quickly solidified under the condition of not improving the ultraviolet exposure intensity, and the photocuring 3D printing of high-solid-phase materials is realized. (2) In the degreasing process, an ultraviolet re-curing process is introduced, so that the shape-preserving degreasing effect is realized, and the problems of collapse, cracks and the like caused by stress change in the traditional degreasing process of the ceramic green body are avoided. (3) In the degreasing process, a photocatalytic degreasing technology is introduced to further finish the decomposition of organic matters, complete degreasing is realized, and the degreasing time is shortened. (4) The technological level of the solid content of the ceramic green body exceeding 90 percent can be realized.

Drawings

The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention and not to limit the invention. In the drawings:

FIG. 1 is a scanning electron micrograph of the ceramic green body degreased in example 1.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Example 1:

step 1: mixing and ball-milling 3 vol% of oxide, wherein the oxide comprises an oxide A and an oxide B, adding 18 vol% of photosensitive resin and 2 vol% of auxiliary agent, stirring and mixing, adding 77 vol% of ceramic powder, stirring and homogenizing to obtain ceramic slurry with the solid content of 82%.

Step 2: setting the wavelength of photocuring to be 400nm, printing the ceramic slurry layer by layer through a DLP type photocuring 3D printer, wherein the thickness of each layer is 10 microns, and forming to obtain a ceramic green body; cleaning the surface of the ceramic green body, drying the ceramic green body in a drying oven at 60 ℃ for 2 hours, transferring the ceramic green body to a glue removing furnace in inert atmosphere, and heating the ceramic green body to 500 ℃ at a heating rate of 2 ℃/min under the irradiation of an ultraviolet lamp with the wavelength of 400 nm; in the process, the temperature is kept for 1 hour when the temperature is increased to 100 ℃ per liter, and degreasing is carried out; drying again, transferring to a sintering furnace in vacuum or inert gas, and sintering at controlled temperature to obtain the ceramic product.

In the scheme, the oxide A is SiO with the thickness of 10nm₂(ii) a Oxide B is 20nm TiO₂. Photosensitive resin urea-formaldehyde resin. The ceramic powder is 250nm Al₂O₃And alkali metal titanate mixture, having a spectral transmittance of 58% under UVA conditions. The auxiliary agent is polyvinylpyrrolidone.

Example 2:

step 1: mixing and ball-milling 4 vol% of oxide, wherein the oxide comprises an oxide A and an oxide B, adding 45 vol% of photosensitive resin and 1 vol% of auxiliary agent, stirring and mixing, adding 50 vol% of ceramic powder, stirring and homogenizing to obtain ceramic slurry with the solid content of 55%.

Step 2: setting the wavelength of photocuring to be 400nm, printing the ceramic slurry layer by layer through an SLA type photocuring 3D printer, wherein the thickness of each layer is 1 mu m, and forming to obtain a ceramic green body; cleaning the surface of the ceramic green body, and drying the ceramic green body in an oven at 60 ℃ for 2 hours; transferring the mixture to a glue discharging furnace in inert atmosphere, and heating to 500 ℃ at the heating rate of 2 ℃/min under the irradiation of an ultraviolet lamp with the wavelength of 400 nm; in the process, the temperature is kept for 1 hour when the temperature is increased to 100 ℃ per liter, and degreasing is carried out; drying again, transferring to a sintering furnace in vacuum or inert gas, and sintering at controlled temperature to obtain the ceramic product.

In this case, the oxide A is 5nm of Al₂O₃(ii) a Oxide B is 15nm TiO₂. The photosensitive resin is a polyaldehyde resin. The ceramic powder is alkali metal titanate with the wavelength of 100nm, and the spectral transmittance under UVA condition is 62%. The auxiliary agent is polyvinylpyrrolidone.

Example 3:

step 1: mixing and ball-milling 1 vol% of oxide, wherein the oxide comprises an oxide A and an oxide B, adding 10 vol% of photosensitive resin and 4 vol% of auxiliary agent, stirring and mixing, adding 85 vol% of ceramic powder, stirring and homogenizing to obtain ceramic slurry with the solid content of 85%.

Step 2: setting the wavelength of photocuring to be 300nm, printing the ceramic slurry layer by layer through a DLP type photocuring 3D printer, wherein the thickness of each layer is 20 microns, and forming to obtain a ceramic green body; cleaning the ceramic green body, drying the ceramic green body in an oven at 55 ℃ for 1 hour, transferring the ceramic green body to a glue removing furnace in an inert atmosphere, and degreasing the ceramic green body under the irradiation of an ultraviolet lamp with the wavelength of 300nm and the set temperature of 150 ℃ by using an oxalic acid catalyst; drying again, transferring to a sintering furnace in vacuum or inert gas, and sintering at controlled temperature to obtain the ceramic product.

In the scheme, the oxide A is SiO with the particle size of 20nm₂、Al₂O₃、ZrO₂One or more of CaO and MgO; the oxide B is 40nm of silicon dioxide surface modified TiO₂. The photosensitive resin is a polyaldehyde resin. The ceramic powder is 500nm Al₂O₃And a spectral transmittance of 52% under UVA conditions. The auxiliary agent is vinyl trimethoxy silane.

Comparative example 1: the oxide a was used for all the oxides, and the rest was the same as in example 1.

Comparative example 2: oxide A is larger in diameter than oxide B, and oxide A is 20nm SiO₂Oxide B is 10nm TiO₂(ii) a The rest is the same as in example 1.

Comparative example 3: the same procedure as in example 1 was repeated except that the urea resin was changed to a polyester acrylate resin.

Comparative example 4: the ceramic powder is Al with average particle diameter of 420nm₂O₃Silicon carbide and zirconium carbide, and the spectral transmittance under UVA conditions was 41%, and the rest was the same as in example 1.

Experiment: the ceramic articles prepared in the examples and comparative examples were subjected to characterization of relative density, skin hardness, appearance, etc., and the results are shown below:

examples	Relative density/%)	Surface hardness/Gpa	Appearance of the product
				Example 1	＞98％	20.6	No deformation and no black spot
Example 2	＞98％	20.5	No deformation and no black spot
				Example 3	＞98％	20.3	No deformation and no black spot
Comparative example 1	＞98％	18.5	Has cracks and black spots
				Comparative example 2	＞98％	19.8	Has cracks and black spots
Comparative example 3	＜98％	18.6	Has cracks and black spots
				Comparative example 4	＜98％	17.5	Having deformation and black spots

And (4) conclusion: from the experimental data of examples 1 to 3, it can be seen that: the optimized ceramic slurry can realize photocuring 3D printing of high solid-phase materials under the condition of not improving the ultraviolet exposure intensity; meanwhile, the surface hardness is high, the problems of collapse, cracks and the like do not occur, and black spots and other impurities do not occur; meanwhile, the relative density of the ceramic product is more than 98 percent.

Comparing example 1 with other comparative examples, it can be seen that: in comparative example 1, because the oxide B is not added, the rayleigh scattering effect is reduced, so that the photocuring molding process is slowed down, the surface solid is poor, and the surface hardness is reduced; the degreasing process becomes slow, and organic macromolecules are decomposed into micromolecular CO₂And H₂The incomplete existence of small molecular organic matters in O causes the occurrence of carbonized black spots in the long-time curing process of the resin; at the same time, the stability of the sintered crystal is reduced. In comparative example 2, the rayleigh scattering effect is weak when the diameter of oxide a is larger than that of oxide B, and no deformation is generated, but black spots exist. In comparative example 3, organic molecules that could not be completely decomposed were generated during degreasing due to resin replacement, so that surface hardness was decreased, and cracks and black spots were generated due to incomplete degreasing. In comparative example 4, since the spectral transmittance of the ceramic powder was less than 50%, the efficiency of curing molding was significantly reduced, so that the surface hardness was reduced and the ceramic device had distortion.

Finally, it should be noted that: although the present invention has been described in detail with reference to the foregoing embodiments, it will be apparent to those skilled in the art that changes may be made in the embodiments and/or equivalents thereof without departing from the spirit and scope of the invention. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.