阅读说明：本技术 一种光固化氮化硅陶瓷及其具有梯度结构制备方法 (Photocuring silicon nitride ceramic and preparation method thereof with gradient structure ) 是由 鲍崇高 王克杰 卢秉恒 宋索成 于 2021-08-05 设计创作，主要内容包括：一种光固化氮化硅陶瓷及其具有梯度结构制备方法,先混合Si3N4粉末和助烧剂形成陶瓷粉体,在陶瓷粉体中加入硬脂酸粉末,形成陶瓷混合粉末,过筛后加入KH560,加入磨球湿磨后干燥过筛待用；再混合聚氨酯、双酚A、HDDA、IBOMA、DPHA、TPGDA、TMPTA和高折射率树脂,加入光引发剂TPO,混匀得到预混液；然后将陶瓷混合粉末和分散剂加入预混液中,搅拌均匀后得到氮化硅陶瓷膏料；最后将氮化硅陶瓷膏料真空除泡后放入打印机料仓内,将梯度多孔结构模型输入后开始打印,采用光固化成型得到具有梯度结构光固化氮化硅陶瓷；本发明可实现梯度结构中孔隙结构及孔隙率的精确控制,突破模具限制实现定制化结构成型,对高温腐蚀性流体粒子的过滤分类及功能陶瓷的结构设计提供捷径。(A photocuring silicon nitride ceramic and its preparation method with gradient structure, mix Si3N4 powder and sintering aid to form ceramic powder first, add stearic acid powder in ceramic powder, form the ceramic mixed powder, add KH560 after sieving, add the ball mill and dry and sieve for subsequent use; mixing polyurethane, bisphenol A, HDDA, IBOMA, DPHA, TPGDA, TMPTA and high refractive index resin, adding a photoinitiator TPO, and uniformly mixing to obtain a premixed solution; then adding the ceramic mixed powder and a dispersant into the premixed liquid, and uniformly stirring to obtain a silicon nitride ceramic paste; finally, placing the silicon nitride ceramic paste into a printer bin after vacuum defoaming, inputting the gradient porous structure model, starting printing, and obtaining the photocuring silicon nitride ceramic with the gradient structure by adopting photocuring molding; the invention can realize the accurate control of the pore structure and the porosity in the gradient structure, break through the limitation of a mould to realize the customized structure forming, and provide shortcuts for the filtration classification of high-temperature corrosive fluid particles and the structural design of functional ceramics.)

1. The photocuring silicon nitride ceramic is characterized in that the material comprises Si3N4 powder, sintering aid, stearic acid powder and KH 560; mixture A, photoinitiator TPO; a dispersant;

the Si3N4 powder and the sintering aid form ceramic powder, the Si3N4 powder accounts for 65-75% of the mass fraction of the ceramic powder, and the rest is the sintering aid; the sintering aid is a mixture of Y2O3 powder, Al2O3 powder and SiO2 powder, wherein Y2O3 powder accounts for 2-8% of the mass fraction of the ceramic powder, Al2O3 powder accounts for 2-6% of the mass fraction of the ceramic powder, and SiO2 powder accounts for 13-30% of the mass fraction of the ceramic powder;

the stearic acid powder accounts for 2-5% of the mass of the ceramic powder;

adding stearic acid powder into the ceramic powder to form ceramic mixed powder; KH560 is 3-8 wt% of the ceramic mixed powder;

mixing polyurethane, bisphenol A, HDDA, IBOMA, DPHA, TPGDA, TMPTA and high-refractive-index resin according to the mass ratio of 0.8-1:2-2.5:1.5-2.5:0.5-1.5:0.5-1.5:1-2:8-12:5-8, wherein the high-refractive-index resin is A-BPET glue-40 to form a mixture A; adding a photoinitiator TPO into the mixture A to form a premixed liquid, wherein the mass of the premixed liquid is 30-60% of that of the ceramic mixed powder, and the mass of the photoinitiator TPO is 4-8% of that of the mixture A;

the dispersant is a mixture of digao 685 and KOS110, the digao 685 is 0.5-0.8% by mass of the ceramic mixed powder, and the KOS110 is 0.5-1% by mass of the ceramic mixed powder.

2. The method for preparing the photocuring silicon nitride ceramic with the gradient structure as claimed in claim 1, which is characterized by comprising the following steps:

step 1: mixing Si3N4 powder and sintering aid to form ceramic powder, wherein the Si3N4 powder accounts for 65-75% of the mass fraction of the ceramic powder, the sintering aid is the mixture of Y2O3 powder, Al2O3 powder and SiO2 powder, wherein the Y2O3 powder accounts for 2-8% of the mass fraction of the ceramic powder, the Al2O3 powder accounts for 2-6% of the mass fraction of the ceramic powder, and the SiO2 powder accounts for 13-30% of the mass fraction of the ceramic powder;

step 2: adding stearic acid powder accounting for 2-5% of the mass of the ceramic powder into the ceramic powder to form ceramic mixed powder; sieving the ceramic mixed powder with a 180-mesh 200-mesh sieve, adding KH560 accounting for 3-8 wt% of the ceramic mixed powder, adding a grinding ball, wet-grinding for 12-20h, drying and sieving for later use;

and step 3: mixing polyurethane, bisphenol A, HDDA, IBOMA, DPHA, TPGDA, TMPTA and high-refractive-index resin according to the mass ratio of 0.8-1:2-2.5:1.5-2.5:0.5-1.5:0.5-1.5:1-2:8-12:5-8, wherein the high-refractive-index resin is A-BPET glue-40 to form a mixture A, adding a photoinitiator TPO accounting for 4-8% of the mass of the mixture A, and uniformly mixing by using a homogenizer to obtain a premixed solution;

and 4, step 4: adding the ceramic mixed powder prepared in the step 2 and a dispersing agent into a premixed liquid, wherein the mass of the premixed liquid is 30-60% of that of the ceramic mixed powder, the dispersing agent is a mixture of Digao 685 and KOS110, the adding amount of the Digao 685 is 0.5-0.8% of that of the ceramic mixed powder, and the adding amount of the KOS110 is 0.5-1% of that of the ceramic mixed powder, and uniformly stirring to obtain a silicon nitride ceramic paste;

and 5: and (3) placing the silicon nitride ceramic paste into a printer bin after vacuum defoaming, inputting the gradient porous structure model, starting printing, and obtaining the photocuring silicon nitride ceramic with the gradient structure by adopting photocuring molding.

3. The method for preparing photocured silicon nitride ceramic with a gradient structure as set forth in claim 2, wherein the method comprises the following steps: in the Si3N4 powder, the ratio of Si3N4 powder with the particle size of 3-5 mu m is 65-75%, and the ratio of Si3N4 powder with the particle size of 0.5-1 mu m is 25-35%.

4. The method for preparing photocured silicon nitride ceramic with a gradient structure as set forth in claim 2, wherein the method comprises the following steps: the particle size of the sintering aid is 0.5-1 μm.

5. The method for preparing photocured silicon nitride ceramic with a gradient structure as set forth in claim 2, wherein the method comprises the following steps: the gradient porous structure model is a gradient porous cone structure.

6. The method for preparing photocured silicon nitride ceramic with a gradient structure as set forth in claim 2, wherein the method comprises the following steps: in addition to optimizing the gradient porous structure model, the silicon nitride ceramic paste and printing parameters can be optimized, the ceramic curing depth is improved by improving the proportion of high-activity resins (TMPTA and DPHA) in the aspect of the silicon nitride ceramic paste, and the rheological property of the paste is improved by adding different dispersants in proportion; in the aspect of printing parameters, the printing process is regulated and controlled by adjusting laser power, printing paths, printing intervals and layering thickness.

7. A photocured silicon nitride ceramic characterized by: the material comprises Si3N4 powder, sintering aid, stearic acid powder and KH 560; mixture A, photoinitiator TPO; a dispersant;

the Si3N4 powder and the sintering aid form ceramic powder, the Si3N4 powder accounts for 73 percent of the mass of the ceramic powder, and the rest is the sintering aid; the sintering aid is a mixture of Y2O3 powder, Al2O3 powder and SiO2 powder, wherein the Y2O3 powder accounts for 5 mass percent of the ceramic powder, the Al2O3 powder accounts for 3 mass percent of the ceramic powder, and the SiO2 powder accounts for 19 mass percent of the ceramic powder; the Si3N4 powder with the particle size of 3 mu m in the Si3N4 powder accounts for 65 percent, the Si3N4 powder with the particle size of 0.5 mu m accounts for 35 percent, and the sintering aid has the particle size of 0.5 mu m; adding stearic acid powder accounting for 3% of the mass of the ceramic powder to form ceramic mixed powder; adding KH560 with 5 wt% of ceramic mixed powder;

mixing polyurethane, bisphenol A, HDDA, IBOMA, DPHA, TPGDA, TMPTA and high-refractive-index resin according to the mass ratio of 0.96:2.25:1.74:0.87:0.87:1.31:10:7.16, wherein the high-refractive-index resin is A-BPET glue-40 to form a mixture A; adding a photoinitiator TPO into the mixture A to form a premixed liquid, wherein the mass of the premixed liquid is 40% of that of the ceramic mixed powder, and the mass of the photoinitiator TPO is 5% of that of the mixture A;

the dispersant is a mixture of digao 685 and KOS110, digao 685 is 0.7% by mass of the ceramic mixed powder, and KOS110 is 0.5% by mass of the ceramic mixed powder.

8. The method for preparing photocured silicon nitride ceramic with a gradient structure according to claim 7, comprising the following steps:

step 1: mixing Si3N4 powder and a sintering aid to form ceramic powder, wherein the Si3N4 powder accounts for 73 mass percent of the ceramic powder, the sintering aid is a mixture of Y2O3 powder, Al2O3 powder and SiO2 powder, the Y2O3 powder accounts for 5 mass percent of the ceramic powder, the Al2O3 powder accounts for 3 mass percent of the ceramic powder, and the SiO2 powder accounts for 19 mass percent of the ceramic powder; the Si3N4 powder with the particle size of 3 mu m in the Si3N4 powder accounts for 65 percent, the Si3N4 powder with the particle size of 0.5 mu m accounts for 35 percent, and the sintering aid has the particle size of 0.5 mu m;

step 2: adding stearic acid powder accounting for 3% of the mass of the ceramic powder into the ceramic powder to form ceramic mixed powder; sieving the ceramic mixed powder with a 180-mesh sieve, adding KH560 with the weight percent of 5 percent of the ceramic mixed powder, adding a grinding ball, wet-grinding for 12 hours, drying and sieving for later use;

and step 3: mixing polyurethane, bisphenol A, HDDA, IBOMA, DPHA, TPGDA, TMPTA and high-refractive-index resin according to the mass ratio of 0.96:2.25:1.74:0.87:0.87:1.31:10:7.16, wherein the high-refractive-index resin is A-BPET glue-40 to form a mixture A, adding a photoinitiator TPO accounting for 5% of the mass of the mixture A, and uniformly mixing by using a homogenizer to obtain a premixed solution;

and 4, step 4: adding the ceramic mixed powder prepared in the step 2 and a dispersing agent into the premixed liquid, wherein the mass of the premixed liquid is 40% of the mass of the ceramic mixed powder, the dispersing agent is a mixture of Digao 685 and KOS110, the adding amount of the Digao 685 is 0.7% of the mass of the ceramic mixed powder, and the adding amount of the KOS110 is 0.5% of the mass of the ceramic mixed powder, and uniformly stirring to obtain a silicon nitride ceramic paste;

and 5: and (3) placing the silicon nitride ceramic paste into a printer bin after vacuum defoaming, inputting the gradient porous structure model, starting printing, and obtaining the photocuring silicon nitride ceramic with the gradient structure by adopting photocuring molding.

9. A photocured silicon nitride ceramic characterized by: the material comprises Si3N4 powder, sintering aid, stearic acid powder and KH 560; mixture A, photoinitiator TPO; a dispersant;

the Si3N4 powder and the sintering aid form ceramic powder, the Si3N4 powder accounts for 65 percent of the mass fraction of the ceramic powder, and the rest is the sintering aid; the sintering aid is a mixture of Y2O3 powder, Al2O3 powder and SiO2 powder, wherein Y2O3 powder accounts for 3% of the mass fraction of the ceramic powder, Al2O3 powder accounts for 2% of the mass fraction of the ceramic powder, and SiO2 powder accounts for 30% of the mass fraction of the ceramic powder; the Si3N4 powder contains 3.5 μm Si3N4 powder at a ratio of 68%, 0.8 μm Si3N4 powder at a ratio of 32%, and the sintering aid has a particle size of 0.8 μm; adding stearic acid powder accounting for 2% of the mass of the ceramic powder to form ceramic mixed powder; adding KH560 with 3 wt% of ceramic mixed powder;

mixing polyurethane, bisphenol A, HDDA, IBOMA, DPHA, TPGDA, TMPTA and high-refractive-index resin according to the mass ratio of 0.8:2: 1: 0.5:0.5:1:8:8, wherein the high-refractive-index resin is A-BPET glue-40 to form a mixture A; adding a photoinitiator into the mixture A to form a premixed liquid, wherein the mass of the premixed liquid is 30% of that of the ceramic mixed powder, and the mass of the photoinitiator TPO is 6% of that of the mixture A;

the dispersant is a mixture of digao 685 and KOS110, digao 685 is 0.5% by mass of the ceramic mixed powder, and KOS110 is 0.5% by mass of the ceramic mixed powder.

10. The method for preparing photocured silicon nitride ceramic with a gradient structure according to claim 9, comprising the following steps:

step 1: mixing Si3N4 powder and a sintering aid to form ceramic powder, wherein the Si3N4 powder accounts for 65 mass percent of the ceramic powder, the sintering aid is a mixture of Y2O3 powder, Al2O3 powder and SiO2 powder, Y2O3 powder accounts for 3 mass percent of the ceramic powder, Al2O3 powder accounts for 2 mass percent of the ceramic powder, and SiO2 powder accounts for 30 mass percent of the ceramic powder; the Si3N4 powder contains 3.5 μm Si3N4 powder at a ratio of 68%, 0.8 μm Si3N4 powder at a ratio of 32%, and the sintering aid has a particle size of 0.8 μm;

step 2: adding stearic acid powder accounting for 2% of the mass of the ceramic powder into the ceramic powder to form ceramic mixed powder; sieving the ceramic mixed powder with a 200-mesh sieve, adding KH560 with 3 wt% of the ceramic mixed powder, adding a grinding ball, wet-grinding for 12h, drying and sieving for later use;

and step 3: mixing polyurethane, bisphenol A, HDDA, IBOMA, DPHA, TPGDA, TMPTA and high-refractive-index resin according to the mass ratio of 0.8:2:1.5:0.5:0.5:1:8:8, wherein the high-refractive-index resin is A-BPET glue-40 to form a mixture A, adding a photoinitiator TPO accounting for 6% of the mass of the mixture A, and uniformly mixing through a homogenizer to obtain a premixed liquid;

and 4, step 4: adding the ceramic mixed powder prepared in the step 2 and a dispersing agent into the premixed liquid, wherein the mass of the premixed liquid is 30% of the mass of the ceramic mixed powder, the dispersing agent is a mixture of Digao 685 and KOS110, the adding amount of the Digao 685 is 0.5% of the mass of the ceramic mixed powder, and the adding amount of the KOS110 is 0.5% of the mass of the ceramic mixed powder, and uniformly stirring to obtain a silicon nitride ceramic paste;

and 5: and (3) removing bubbles from the silicon nitride ceramic paste in vacuum, putting the silicon nitride ceramic paste into a printer bin, inputting a gradient porous structure model, starting printing, and carrying out photocuring molding to obtain the photocuring silicon nitride ceramic with the gradient porous cone structure.

11. A photocured silicon nitride ceramic characterized by: the material comprises Si3N4 powder, sintering aid, stearic acid powder and KH 560; mixture A, photoinitiator TPO; a dispersant;

the Si3N4 powder and the sintering aid form ceramic powder, the Si3N4 powder accounts for 70 percent of the mass fraction of the ceramic powder, and the rest is the sintering aid; the sintering aid is a mixture of Y2O3 powder, Al2O3 powder and SiO2 powder, wherein Y2O3 powder accounts for 6 mass percent of the ceramic powder, Al2O3 powder accounts for 4 mass percent of the ceramic powder, and SiO2 powder accounts for 20 mass percent of the ceramic powder; the Si3N4 powder contains 4.0 μm Si3N4 powder 70%, 0.5 μm Si3N4 powder 30%, and the sintering aid has a particle size of 1.0 μm; adding stearic acid powder accounting for 3.5 percent of the mass of the ceramic powder to form ceramic mixed powder; adding KH560 with 5.5 wt% of ceramic mixed powder;

mixing polyurethane, bisphenol A, HDDA, IBOMA, DPHA, TPGDA, TMPTA and high-refractive-index resin according to the mass ratio of 0.9:2.3:2.0:1.0:1.0:1.5:10:6.5 to form a mixture A, wherein the high-refractive-index resin is A-BPET glue-40; adding a photoinitiator into the mixture A to form a premixed liquid, wherein the mass of the premixed liquid is 45% of that of the ceramic mixed powder, and the mass of the photoinitiator TPO is 8% of that of the mixture A;

the dispersant was a mixture of digao 685 and KOS110, digao 685 was 0.6% by mass of the ceramic mixed powder, and KOS110 was 0.8% by mass of the ceramic mixed powder.

12. The method for preparing photocured silicon nitride ceramic with a gradient structure according to claim 11, comprising the following steps:

step 1: mixing Si3N4 powder and a sintering aid to form ceramic powder, wherein the Si3N4 powder accounts for 70% of the mass fraction of the ceramic powder, the sintering aid is a mixture of Y2O3 powder, Al2O3 powder and SiO2 powder, the Y2O3 powder accounts for 6% of the mass fraction of the ceramic powder, the Al2O3 powder accounts for 4% of the mass fraction of the ceramic powder, and the SiO2 powder accounts for 20% of the mass fraction of the ceramic powder; the Si3N4 powder contains 4.0 μm Si3N4 powder 70%, 0.5 μm Si3N4 powder 30%, and the sintering aid has a particle size of 1.0 μm;

step 2: adding stearic acid powder accounting for 3.5 percent of the mass of the ceramic powder into the ceramic powder to form ceramic mixed powder; sieving the ceramic mixed powder with a 220-mesh sieve, adding KH560 with the weight percent of 5.5 percent of the ceramic mixed powder, adding a grinding ball, wet-grinding for 16 hours, drying and sieving for later use;

and step 3: mixing polyurethane, bisphenol A, HDDA, IBOMA, DPHA, TPGDA, TMPTA and high-refractive-index resin according to the mass ratio of 0.9:2.3:2.0:1.0:1.0:1.5:10:6.5, wherein the high-refractive-index resin is A-BPET glue-40 to form a mixture A, adding a photoinitiator TPO accounting for 8% of the mass of the mixture A, and uniformly mixing by using a homogenizer to obtain a premixed solution;

and 4, step 4: adding the ceramic mixed powder prepared in the step 2 and a dispersing agent into the premixed liquid, wherein the mass of the premixed liquid is 45% of the mass of the ceramic mixed powder, the dispersing agent is a mixture of Digao 685 and KOS110, the adding amount of the Digao 685 is 0.6% of the mass of the ceramic mixed powder, and the adding amount of the KOS110 is 0.8% of the mass of the ceramic mixed powder, and uniformly stirring to obtain a silicon nitride ceramic paste;

and 5: and (3) placing the silicon nitride ceramic paste into a printer bin after vacuum defoaming, inputting the gradient porous structure model, starting printing, and obtaining the photocuring silicon nitride ceramic with the gradient porous structure by adopting photocuring molding.

13. A photocured silicon nitride ceramic characterized by: the material comprises Si3N4 powder, sintering aid, stearic acid powder and KH 560; mixture A, photoinitiator TPO; a dispersant;

the Si3N4 powder and the sintering aid form ceramic powder, the Si3N4 powder accounts for 75 percent of the mass fraction of the ceramic powder, and the rest is the sintering aid; the sintering aid is a mixture of Y2O3 powder, Al2O3 powder and SiO2 powder, wherein Y2O3 powder accounts for 8 mass percent of the ceramic powder, Al2O3 powder accounts for 4 mass percent of the ceramic powder, and SiO2 powder accounts for 13 mass percent of the ceramic powder; the Si3N4 powder has a Si3N4 powder content of 75% at a particle size of 5 μm, a Si3N4 powder content of 25% at a particle size of 1.0 μm at a particle size of 1 μm; adding stearic acid powder accounting for 5% of the mass of the ceramic powder to form ceramic mixed powder; adding KH560 with 8 wt% of ceramic mixed powder;

mixing polyurethane, bisphenol A, HDDA, IBOMA, DPHA, TPGDA, TMPTA and high-refractive-index resin according to the mass ratio of 1:2.5:2.5:1.5:1.5:2:12:5, wherein the high-refractive-index resin is A-BPET glue-40 to form a mixture A; adding a photoinitiator into the mixture A to form a premixed liquid, wherein the mass of the premixed liquid is 60% of the mass of the ceramic mixed powder, and the mass of the photoinitiator TPO is 4% of the mass of the mixture A;

the dispersant is a mixture of digao 685 and KOS110, digao 685 is 0.8% by mass of the ceramic mixed powder, and KOS110 is 1% by mass of the ceramic mixed powder.

14. The method for preparing a photocured silicon nitride ceramic with a gradient structure as set forth in claim 13, comprising the steps of:

step 1: mixing Si3N4 powder and a sintering aid to form ceramic powder, wherein the Si3N4 powder accounts for 75% of the mass fraction of the ceramic powder, the sintering aid is a mixture of Y2O3 powder, Al2O3 powder and SiO2 powder, the Y2O3 powder accounts for 8% of the mass fraction of the ceramic powder, the Al2O3 powder accounts for 4% of the mass fraction of the ceramic powder, and the SiO2 powder accounts for 13% of the mass fraction of the ceramic powder; the Si3N4 powder has a Si3N4 powder content of 75% at a particle size of 5 μm, a Si3N4 powder content of 25% at a particle size of 1.0 μm at a particle size of 1 μm;

step 2: adding stearic acid powder accounting for 5% of the mass of the ceramic powder into the ceramic powder to form ceramic mixed powder; sieving the ceramic mixed powder with a 200-mesh sieve, adding KH560 with 8 wt% of the ceramic mixed powder, adding a grinding ball, wet-grinding for 20h, drying and sieving for later use;

and step 3: mixing a mixed solution of polyurethane, bisphenol A, HDDA, IBOMA, DPHA, TPGDA and TMPTA and a high-refractive-index resin according to a mass ratio of 1:2.5:2.5:1.5:1.5:2:12:5, wherein the high-refractive-index resin is A-BPET glue-40 to form a mixture A, adding a photoinitiator TPO accounting for 4% of the mass of the mixture A, and uniformly mixing by using a homogenizer to obtain a premixed solution;

and 4, step 4: adding the ceramic mixed powder prepared in the step 2 and a dispersing agent into the premixed liquid, wherein the mass of the premixed liquid is 60% of the mass of the ceramic mixed powder, the dispersing agent is a mixture of Digao 685 and KOS110, the adding amount of the Digao 685 is 0.8% of the mass of the ceramic mixed powder, and the adding amount of the KOS110 is 1% of the mass of the ceramic mixed powder, and uniformly stirring to obtain a silicon nitride ceramic paste;

and 5: and (3) placing the silicon nitride ceramic paste into a printer bin after vacuum defoaming, inputting the gradient porous structure model, starting printing, and obtaining the photocuring silicon nitride ceramic with the gradient porous structure by adopting photocuring molding.

Technical Field

The invention belongs to the technical field of silicon nitride ceramic manufacturing, and particularly relates to a photocuring silicon nitride ceramic and a preparation method thereof with a gradient structure.

Background

The nitride ceramic material is a material capable of realizing structure-function integration, has excellent performances in the aspects of mechanics, chemistry, electricity, thermology and the like, has the advantage that oxide ceramics and metal ceramics cannot be replaced in the field of heat-resistant and high-temperature-resistant structural materials, and has wide application in the industries of metallurgy, aviation, chemical industry, ceramics, electronics, machinery, semiconductors and the like. With the development of science and technology, the application field and the use requirement of the silicon nitride ceramic are more and more strict. At present, the traditional manufacturing method is to obtain the required ceramic component by compression molding of silicon nitride powder or slip casting, gel film casting and the like of ceramic slurry, sintering and machining in combination, so that the processing cost is greatly increased, the production efficiency is reduced, complex parts with hollow and gradient structures are difficult to prepare, and the application and development of silicon nitride ceramic are severely limited. Aiming at the problem, numerous scholars propose a net size forming method, the limitation of the traditional die is broken through, the component with the required shape is subjected to personalized customized forming by adopting an additive manufacturing method, and the technology can be used for preparing silicon nitride ceramics with a complex structure, so that the manufacturing efficiency is improved, and the application field of the silicon nitride ceramics is widened.

Gradient porous ceramics refer to ceramics with regular variation of porosity or pore diameter or pore structure with sample size, i.e. designability of structure and composition. The structure is particularly suitable for separation of mixed fluid containing fine particles with high temperature, corrosiveness and the like, dust removal of high-temperature flue gas, fine filtration and the like. At present, gradient porous ceramics have been used for solid-liquid separation membranes, catalyst carriers, sensor supports, and the like. Meanwhile, due to its good high-temperature performance, it is also used as a core tube for alloy casting, a thermal barrier coating, an engine combustion chamber, etc. In addition, in the field of functional materials, the gradient-structure porous ceramic can combine a radar absorbing/transmitting material with a micro-design structure. The weight reduction of the material can be realized, the gradient structure can be used for scattering or penetrating the electromagnetic waves, and the controllability of the electromagnetic waves can be greatly improved by the gradually-changed hole structure.

No relevant literature on the preparation of photocuring silicon nitride ceramics with a gradient structure is published at present.

Disclosure of Invention

In order to overcome the defects of the prior art, the invention aims to provide a photocuring silicon nitride ceramic and a preparation method thereof with a gradient structure, which can realize rapid manufacture of complex structural parts without a mold and greatly save the mold cost and the time cost under batch production; in addition, because the structure of the photocuring forming green body is determined by the printing model, the method can realize the accurate control of the pore structure and the porosity in the gradient structure, and break through the limitation of a mold to realize the formation of a customized structure, and the high-precision gradient porous structure provides a shortcut for the filtration and classification of high-temperature corrosive fluid particles and the structural design of functional ceramics.

In order to achieve the purpose, the invention adopts the technical scheme that:

a photocuring silicon nitride ceramic comprises Si3N4 powder, sintering aid, stearic acid powder and KH 560; mixture A, photoinitiator TPO; a dispersant;

the Si3N4 powder and the sintering aid form ceramic powder, the Si3N4 powder accounts for 65-75% of the mass fraction of the ceramic powder, and the rest is the sintering aid; the sintering aid is a mixture of Y2O3 powder, Al2O3 powder and SiO2 powder, wherein Y2O3 powder accounts for 2-8% of the mass fraction of the ceramic powder, Al2O3 powder accounts for 2-6% of the mass fraction of the ceramic powder, and SiO2 powder accounts for 13-30% of the mass fraction of the ceramic powder;

the stearic acid powder accounts for 2-5% of the mass of the ceramic powder;

adding stearic acid powder into the ceramic powder to form ceramic mixed powder; KH560 is 3-8 wt% of the ceramic mixed powder;

mixing polyurethane, bisphenol A, HDDA, IBOMA, DPHA, TPGDA, TMPTA and high-refractive-index resin according to the mass ratio of 0.8-1:2-2.5:1.5-2.5:0.5-1.5:0.5-1.5:1-2:8-12:5-8, wherein the high-refractive-index resin is A-BPET glue-40 to form a mixture A; adding a photoinitiator TPO into the mixture A to form a premixed liquid, wherein the mass of the premixed liquid is 30-60% of that of the ceramic mixed powder, and the mass of the photoinitiator TPO is 4-8% of that of the mixture A;

the dispersant is a mixture of digao 685 and KOS110, the digao 685 is 0.5-0.8% by mass of the ceramic mixed powder, and the KOS110 is 0.5-1% by mass of the ceramic mixed powder.

A preparation method of photocuring silicon nitride ceramic with a gradient structure comprises the following steps:

step 1: mixing Si3N4 powder and sintering aid to form ceramic powder, wherein the Si3N4 powder accounts for 65-75% of the mass fraction of the ceramic powder, the sintering aid is the mixture of Y2O3 powder, Al2O3 powder and SiO2 powder, wherein the Y2O3 powder accounts for 2-8% of the mass fraction of the ceramic powder, the Al2O3 powder accounts for 2-6% of the mass fraction of the ceramic powder, and the SiO2 powder accounts for 13-30% of the mass fraction of the ceramic powder;

step 2: adding stearic acid powder accounting for 2-5% of the mass of the ceramic powder into the ceramic powder to form ceramic mixed powder; sieving the ceramic mixed powder with a 180-mesh 200-mesh sieve, adding KH560 accounting for 3-8 wt% of the ceramic mixed powder, adding a grinding ball, wet-grinding for 12-20h, drying and sieving for later use;

and step 3: mixing polyurethane, bisphenol A, HDDA, IBOMA, DPHA, TPGDA, TMPTA and high-refractive-index resin according to the mass ratio of 0.8-1:2-2.5:1.5-2.5:0.5-1.5:0.5-1.5:1-2:8-12:5-8, wherein the high-refractive-index resin is A-BPET glue-40 to form a mixture A, adding a photoinitiator TPO accounting for 4-8% of the mass of the mixture A, and uniformly mixing by using a homogenizer to obtain a premixed solution;

and 4, step 4: adding the ceramic mixed powder prepared in the step 2 and a dispersing agent into a premixed liquid, wherein the mass of the premixed liquid is 30-60% of that of the ceramic mixed powder, the dispersing agent is a mixture of Digao 685 and KOS110, the adding amount of the Digao 685 is 0.5-0.8% of that of the ceramic mixed powder, and the adding amount of the KOS110 is 0.5-1% of that of the ceramic mixed powder, and uniformly stirring to obtain a silicon nitride ceramic paste;

and 5: and (3) placing the silicon nitride ceramic paste into a printer bin after vacuum defoaming, inputting the gradient porous structure model, starting printing, and obtaining the photocuring silicon nitride ceramic with the gradient structure by adopting photocuring molding.

In the Si3N4 powder, the ratio of Si3N4 powder with the particle size of 3-5 mu m is 65-75%, and the ratio of Si3N4 powder with the particle size of 0.5-1 mu m is 25-35%.

The particle size of the sintering aid is 0.5-1 μm.

The gradient porous structure model is a gradient porous cone structure.

In addition to optimizing the gradient porous structure model, the silicon nitride ceramic paste and printing parameters can be optimized, the ceramic curing depth is improved by improving the proportion of high-activity resins (TMPTA and DPHA) in the aspect of the silicon nitride ceramic paste, and the rheological property of the paste is improved by adding different dispersants in proportion; in the aspect of printing parameters, the printing process is regulated and controlled by adjusting laser power, printing paths, printing intervals and layering thickness.

The invention has the beneficial effects that:

the invention adopts photocuring molding, can directly manufacture a gradient porous ceramic structure prototype by a CAD digital model, has high processing speed and short production period of products, and does not need cutting tools and dies; the mould with complicated structure and fine size can be manufactured, and especially, the mould with complicated internal structure and difficult access of a common cutting tool can be easily formed at one time. The automation degree of the forming process is high, and the forming process can be completely automated after the ceramic SLA system starts to process until the prototype manufacturing of the gradient porous structure ceramic is completed. In addition, the photocuring molding can be used for realizing remote control by on-line operation, and the automatic production is promoted.

The invention adopts the photocuring molding gradient structure, has high dimensional precision (+/-0.1 mm), can accurately control the structure and porosity of pores in the porous structure, and has excellent surface quality on the solid part.

The invention adopts photocuring molding to visualize the CAD digital model so as to reduce the cost of error repair. In addition, the results of the computer simulation calculations can be verified and checked.

Drawings

FIG. 1(a) is a gradient porous structure model of example 1 of the present invention; FIG. b shows that the light-cured silicon nitride ceramic having a gradient structure is obtained in example 1 of the present invention.

FIG. 2 shows that the light-cured silicon nitride ceramic with a gradient structure is obtained in example 2 of the present invention.

Detailed Description

The present invention will be described in detail below with reference to the accompanying drawings.

Example 1, a photocurable silicon nitride ceramic whose material includes Si3N4 powder, a sintering aid, stearic acid powder, KH 560; mixture A, photoinitiator TPO; a dispersant;

the Si3N4 powder and the sintering aid form ceramic powder, the Si3N4 powder accounts for 73 percent of the mass of the ceramic powder, and the rest is the sintering aid; the sintering aid is a mixture of Y2O3 powder, Al2O3 powder and SiO2 powder, wherein the Y2O3 powder accounts for 5 mass percent of the ceramic powder, the Al2O3 powder accounts for 3 mass percent of the ceramic powder, and the SiO2 powder accounts for 19 mass percent of the ceramic powder; the Si3N4 powder with the particle size of 3 mu m in the Si3N4 powder accounts for 65 percent, the Si3N4 powder with the particle size of 0.5 mu m accounts for 35 percent, and the sintering aid has the particle size of 0.5 mu m; adding stearic acid powder accounting for 3% of the mass of the ceramic powder to form ceramic mixed powder; adding KH560 with 5 wt% of ceramic mixed powder;

mixing polyurethane, bisphenol A, HDDA, IBOMA, DPHA, TPGDA, TMPTA and high-refractive-index resin according to the mass ratio of 0.96:2.25:1.74:0.87:0.87:1.31:10:7.16, wherein the high-refractive-index resin is A-BPET glue-40 to form a mixture A; adding a photoinitiator TPO into the mixture A to form a premixed liquid, wherein the mass of the premixed liquid is 40% of that of the ceramic mixed powder, and the mass of the photoinitiator TPO is 5% of that of the mixture A;

in order to improve the uniform dispersibility, the dispersant is a mixture of digao 685 and KOS110, digao 685 is 0.7% by mass of the ceramic mixed powder, and KOS110 is 0.5% by mass of the ceramic mixed powder.

A preparation method of photocuring silicon nitride ceramic with a gradient structure comprises the following steps:

step 1: mixing Si3N4 powder and a sintering aid to form ceramic powder, wherein the Si3N4 powder accounts for 73 mass percent of the ceramic powder, the sintering aid is a mixture of Y2O3 powder, Al2O3 powder and SiO2 powder, the Y2O3 powder accounts for 5 mass percent of the ceramic powder, the Al2O3 powder accounts for 3 mass percent of the ceramic powder, and the SiO2 powder accounts for 19 mass percent of the ceramic powder; the Si3N4 powder with the particle size of 3 mu m in the Si3N4 powder accounts for 65 percent, the Si3N4 powder with the particle size of 0.5 mu m accounts for 35 percent, and the sintering aid has the particle size of 0.5 mu m;

step 2: adding stearic acid powder accounting for 3% of the mass of the ceramic powder into the ceramic powder to form ceramic mixed powder; sieving the ceramic mixed powder with a 180-mesh sieve, adding KH560 with the weight percent of 5 percent of the ceramic mixed powder, adding a grinding ball, wet-grinding for 12 hours, drying and sieving for later use;

and step 3: mixing polyurethane, bisphenol A, HDDA, IBOMA, DPHA, TPGDA, TMPTA and high-refractive-index resin according to the mass ratio of 0.96:2.25:1.74:0.87:0.87:1.31:10:7.16, wherein the high-refractive-index resin is A-BPET glue-40 to form a mixture A, adding a photoinitiator TPO accounting for 5% of the mass of the mixture A, and uniformly mixing by using a homogenizer to obtain a premixed solution;

and 4, step 4: adding the ceramic mixed powder prepared in the step 2 and a dispersing agent into the premixed liquid, wherein the mass of the premixed liquid is 40% of the mass of the ceramic mixed powder, the dispersing agent is a mixture of Digao 685 and KOS110, the adding amount of the Digao 685 is 0.7% of the mass of the ceramic mixed powder, and the adding amount of the KOS110 is 0.5% of the mass of the ceramic mixed powder, and uniformly stirring to obtain a silicon nitride ceramic paste;

and 5: and (3) placing the silicon nitride ceramic paste into a printer bin after vacuum defoaming, inputting the gradient porous structure model, starting printing, and obtaining the photocuring silicon nitride ceramic with the gradient structure by adopting photocuring molding.

The gradient porous structure model adopted in this embodiment is composed of two layers of structures as shown in fig. 1(a), wherein the upper layer is a double-row porous structure (the pore diameter is 0.55 × 0.5mm, 0.5 × 0.5mm), the lower layer is a solid structure, and the integrated molding and the personalized customization of the structure can be realized by photocuring, and as shown in fig. 1(b), the obtained photocuring silicon nitride ceramic with the gradient structure has uniform pores, uniform pore diameter (can be controlled by a printing model), distinct edges and corners, and no bending deformation and over-curing burr phenomenon.

Example 2, a photocurable silicon nitride ceramic whose material includes Si3N4 powder, a sintering aid, stearic acid powder, KH 560; mixture A, photoinitiator TPO; a dispersant;

the Si3N4 powder and the sintering aid form ceramic powder, the Si3N4 powder accounts for 65 percent of the mass fraction of the ceramic powder, and the rest is the sintering aid; the sintering aid is a mixture of Y2O3 powder, Al2O3 powder and SiO2 powder, wherein Y2O3 powder accounts for 3% of the mass fraction of the ceramic powder, Al2O3 powder accounts for 2% of the mass fraction of the ceramic powder, and SiO2 powder accounts for 30% of the mass fraction of the ceramic powder; the Si3N4 powder contains 3.5 μm Si3N4 powder at a ratio of 68%, 0.8 μm Si3N4 powder at a ratio of 32%, and the sintering aid has a particle size of 0.8 μm; adding stearic acid powder accounting for 2% of the mass of the ceramic powder to form ceramic mixed powder; adding KH560 with 3 wt% of ceramic mixed powder;

mixing polyurethane, bisphenol A, HDDA, IBOMA, DPHA, TPGDA, TMPTA and high-refractive-index resin according to the mass ratio of 0.8:2: 1: 0.5:0.5:1:8:8, wherein the high-refractive-index resin is A-BPET glue-40 to form a mixture A; adding a photoinitiator into the mixture A to form a premixed liquid, wherein the mass of the premixed liquid is 30% of that of the ceramic mixed powder, and the mass of the photoinitiator TPO is 6% of that of the mixture A;

in order to improve the uniform dispersibility, the dispersant is a mixture of digao 685 and KOS110, digao 685 is 0.5% by mass of the ceramic mixed powder, and KOS110 is 0.5% by mass of the ceramic mixed powder.

A preparation method of photocuring silicon nitride ceramic with a gradient structure comprises the following steps:

step 1: mixing Si3N4 powder and a sintering aid to form ceramic powder, wherein the Si3N4 powder accounts for 65 mass percent of the ceramic powder, the sintering aid is a mixture of Y2O3 powder, Al2O3 powder and SiO2 powder, Y2O3 powder accounts for 3 mass percent of the ceramic powder, Al2O3 powder accounts for 2 mass percent of the ceramic powder, and SiO2 powder accounts for 30 mass percent of the ceramic powder; the Si3N4 powder contains 3.5 μm Si3N4 powder at a ratio of 68%, 0.8 μm Si3N4 powder at a ratio of 32%, and the sintering aid has a particle size of 0.8 μm;

step 2: adding stearic acid powder accounting for 2% of the mass of the ceramic powder into the ceramic powder to form ceramic mixed powder; sieving the ceramic mixed powder with a 200-mesh sieve, adding KH560 with 3 wt% of the ceramic mixed powder, adding a grinding ball, wet-grinding for 12h, drying and sieving for later use;

and step 3: mixing polyurethane, bisphenol A, HDDA, IBOMA, DPHA, TPGDA, TMPTA and high-refractive-index resin according to the mass ratio of 0.8:2:1.5:0.5:0.5:1:8:8, wherein the high-refractive-index resin is A-BPET glue-40 to form a mixture A, adding a photoinitiator TPO accounting for 6% of the mass of the mixture A, and uniformly mixing through a homogenizer to obtain a premixed liquid;

and 4, step 4: adding the ceramic mixed powder prepared in the step 2 and a dispersing agent into the premixed liquid, wherein the mass of the premixed liquid is 30% of the mass of the ceramic mixed powder, the dispersing agent is a mixture of Digao 685 and KOS110, the adding amount of the Digao 685 is 0.5% of the mass of the ceramic mixed powder, and the adding amount of the KOS110 is 0.5% of the mass of the ceramic mixed powder, and uniformly stirring to obtain a silicon nitride ceramic paste;

and 5: and (3) placing the silicon nitride ceramic paste into a printer bin after vacuum defoaming, inputting the gradient porous structure model, starting printing, and obtaining the photocuring silicon nitride ceramic with the gradient porous cone structure by adopting photocuring molding.

In the gradient porous cone structure adopted in this embodiment, as shown in fig. 2, the obtained photocuring silicon nitride ceramic cone body with a three-layer (double-layer porous + single-layer solid) gradient structure has uniform pores, uniform diameters controllable by a printing model, distinct edges and corners, smooth surface and no bending deformation and over-curing burr phenomenon.

Example 3, a photocurable silicon nitride ceramic whose material includes Si3N4 powder, a sintering aid, stearic acid powder, KH 560; mixture A, photoinitiator TPO; a dispersant;

the Si3N4 powder and the sintering aid form ceramic powder, the Si3N4 powder accounts for 70 percent of the mass fraction of the ceramic powder, and the rest is the sintering aid; the sintering aid is a mixture of Y2O3 powder, Al2O3 powder and SiO2 powder, wherein Y2O3 powder accounts for 6 mass percent of the ceramic powder, Al2O3 powder accounts for 4 mass percent of the ceramic powder, and SiO2 powder accounts for 20 mass percent of the ceramic powder; the Si3N4 powder contains 4.0 μm Si3N4 powder 70%, 0.5 μm Si3N4 powder 30%, and the sintering aid has a particle size of 1.0 μm; adding stearic acid powder accounting for 3.5 percent of the mass of the ceramic powder to form ceramic mixed powder; adding KH560 with 5.5 wt% of ceramic mixed powder;

mixing polyurethane, bisphenol A, HDDA, IBOMA, DPHA, TPGDA, TMPTA and high-refractive-index resin according to the mass ratio of 0.9:2.3:2.0:1.0:1.0:1.5:10:6.5 to form a mixture A, wherein the high-refractive-index resin is A-BPET glue-40; adding a photoinitiator into the mixture A to form a premixed liquid, wherein the mass of the premixed liquid is 45% of that of the ceramic mixed powder, and the mass of the photoinitiator TPO is 8% of that of the mixture A;

in order to improve the uniform dispersibility, the dispersant is a mixture of digao 685 and KOS110, digao 685 is 0.6% by mass of the ceramic mixed powder, and KOS110 is 0.8% by mass of the ceramic mixed powder.

A preparation method of photocuring silicon nitride ceramic with a gradient structure comprises the following steps:

step 1: mixing Si3N4 powder and a sintering aid to form ceramic powder, wherein the Si3N4 powder accounts for 70% of the mass fraction of the ceramic powder, the sintering aid is a mixture of Y2O3 powder, Al2O3 powder and SiO2 powder, the Y2O3 powder accounts for 6% of the mass fraction of the ceramic powder, the Al2O3 powder accounts for 4% of the mass fraction of the ceramic powder, and the SiO2 powder accounts for 20% of the mass fraction of the ceramic powder; the Si3N4 powder contains 4.0 μm Si3N4 powder 70%, 0.5 μm Si3N4 powder 30%, and the sintering aid has a particle size of 1.0 μm;

step 2: adding stearic acid powder accounting for 3.5 percent of the mass of the ceramic powder into the ceramic powder to form ceramic mixed powder; sieving the ceramic mixed powder with a 220-mesh sieve, adding KH560 with the weight percent of 5.5 percent of the ceramic mixed powder, adding a grinding ball, wet-grinding for 16 hours, drying and sieving for later use;

and step 3: mixing polyurethane, bisphenol A, HDDA, IBOMA, DPHA, TPGDA, TMPTA and high-refractive-index resin according to the mass ratio of 0.9:2.3:2.0:1.0:1.0:1.5:10:6.5, wherein the high-refractive-index resin is A-BPET glue-40 to form a mixture A, adding a photoinitiator TPO accounting for 8% of the mass of the mixture A, and uniformly mixing by using a homogenizer to obtain a premixed solution;

and 4, step 4: adding the ceramic mixed powder prepared in the step 2 and a dispersing agent into the premixed liquid, wherein the mass of the premixed liquid is 45% of the mass of the ceramic mixed powder, the dispersing agent is a mixture of Digao 685 and KOS110, the adding amount of the Digao 685 is 0.6% of the mass of the ceramic mixed powder, and the adding amount of the KOS110 is 0.8% of the mass of the ceramic mixed powder, and uniformly stirring to obtain a silicon nitride ceramic paste;

and 5: and (3) placing the silicon nitride ceramic paste into a printer bin after vacuum defoaming, inputting the gradient porous structure model, starting printing, and obtaining the photocuring silicon nitride ceramic with the gradient porous structure by adopting photocuring molding.

Example 4, a photocurable silicon nitride ceramic whose material includes Si3N4 powder, a sintering aid, stearic acid powder, KH 560; mixture A, photoinitiator TPO; a dispersant;

the Si3N4 powder and the sintering aid form ceramic powder, the Si3N4 powder accounts for 75 percent of the mass fraction of the ceramic powder, and the rest is the sintering aid; the sintering aid is a mixture of Y2O3 powder, Al2O3 powder and SiO2 powder, wherein Y2O3 powder accounts for 8 mass percent of the ceramic powder, Al2O3 powder accounts for 4 mass percent of the ceramic powder, and SiO2 powder accounts for 13 mass percent of the ceramic powder; the Si3N4 powder has a Si3N4 powder content of 75% at a particle size of 5 μm, a Si3N4 powder content of 25% at a particle size of 1.0 μm at a particle size of 1 μm; adding stearic acid powder accounting for 5% of the mass of the ceramic powder to form ceramic mixed powder; adding KH560 with 8 wt% of ceramic mixed powder;

mixing polyurethane, bisphenol A, HDDA, IBOMA, DPHA, TPGDA, TMPTA and high-refractive-index resin according to the mass ratio of 1:2.5:2.5:1.5:1.5:2:12:5, wherein the high-refractive-index resin is A-BPET glue-40 to form a mixture A; adding a photoinitiator into the mixture A to form a premixed liquid, wherein the mass of the premixed liquid is 60% of the mass of the ceramic mixed powder, and the mass of the photoinitiator TPO is 4% of the mass of the mixture A;

in order to improve uniform dispersibility, the dispersant is a mixture of digao 685 and KOS110, digao 685 is 0.8% by mass of the ceramic mixed powder, and KOS110 is 1% by mass of the ceramic mixed powder.

A preparation method of photocuring silicon nitride ceramic with a gradient structure comprises the following steps:

step 1: mixing Si3N4 powder and a sintering aid to form ceramic powder, wherein the Si3N4 powder accounts for 75% of the mass fraction of the ceramic powder, the sintering aid is a mixture of Y2O3 powder, Al2O3 powder and SiO2 powder, the Y2O3 powder accounts for 8% of the mass fraction of the ceramic powder, the Al2O3 powder accounts for 4% of the mass fraction of the ceramic powder, and the SiO2 powder accounts for 13% of the mass fraction of the ceramic powder; the Si3N4 powder has a Si3N4 powder content of 75% at a particle size of 5 μm, a Si3N4 powder content of 25% at a particle size of 1.0 μm at a particle size of 1 μm;

step 2: adding stearic acid powder accounting for 5% of the mass of the ceramic powder into the ceramic powder to form ceramic mixed powder; sieving the ceramic mixed powder with a 200-mesh sieve, adding KH560 with 8 wt% of the ceramic mixed powder, adding a grinding ball, wet-grinding for 20h, drying and sieving for later use;

and step 3: mixing a mixed solution of polyurethane, bisphenol A, HDDA, IBOMA, DPHA, TPGDA and TMPTA and a high-refractive-index resin according to a mass ratio of 1:2.5:2.5:1.5:1.5:2:12:5, wherein the high-refractive-index resin is A-BPET glue-40 to form a mixture A, adding a photoinitiator TPO accounting for 4% of the mass of the mixture A, and uniformly mixing by using a homogenizer to obtain a premixed solution;

and 4, step 4: adding the ceramic mixed powder prepared in the step 2 and a dispersing agent into the premixed liquid, wherein the mass of the premixed liquid is 60% of the mass of the ceramic mixed powder, the dispersing agent is a mixture of Digao 685 and KOS110, the adding amount of the Digao 685 is 0.8% of the mass of the ceramic mixed powder, and the adding amount of the KOS110 is 1% of the mass of the ceramic mixed powder, and uniformly stirring to obtain a silicon nitride ceramic paste;

and 5: and (3) placing the silicon nitride ceramic paste into a printer bin after vacuum defoaming, inputting the gradient porous structure model, starting printing, and obtaining the photocuring silicon nitride ceramic with the gradient porous structure by adopting photocuring molding.