WO2017092013A1

WO2017092013A1 - Method for preparing dentiform shaped ceramics

Info

Publication number: WO2017092013A1
Application number: PCT/CN2015/096354
Authority: WO
Inventors: 伍尚华; 伍海东; 刘伟; 周茂鹏; 吴子薇; 程利霞; 陈仕晰
Original assignee: 广东工业大学
Priority date: 2015-12-03
Filing date: 2015-12-03
Publication date: 2017-06-08

Abstract

Provided is a method for preparing dentiform shaped ceramics, comprising: step 1) slurry preparation: weighing the following components in mass percentage and mixing the components well to obtain a slurry: 20-75% of ceramic powder, 10-70% of a pre-mixed solution, 0.1-5% of a photoinitiator, 0.1-5% of a dispersing agent and 0.1-5% of a surfactant, the pre-mixed solution being composed of an organic solute and a solvent, the mass of the solvent being 20-85% of the mass of the pre-mixed solution, and the organic solute being at least one of acrylamide, dimethyl acrylate, methacrylamide, 2-hydroxyethyl methacrylate and N,N'-methylenebisacrylamide; and step 2) forming: placing the slurry into a stereo lithography apparatus and delineating a blank according to the designed ceramic shape by a stereo lithography apparatus method, then subjecting the blank to processing successively in a drying step, a degreasing step and a sintering step to prepare the dentiform shaped ceramics.

Description

Method for preparing tooth-shaped shaped ceramic

Technical field

The invention relates to the technical field of ceramic preparation, in particular to a preparation method of a tooth shaped shaped ceramic.

Background technique

Multi-tooth oxide ceramic parts are used in a wide range of applications in the fields of machinery, chemicals and automobiles, such as zirconia or alumina ceramic gears and ceramic spirals. Current molding methods for manufacturing such multi-tooth oxide ceramic parts include cold isostatic pressing, dry pressing, grouting, and hot die casting. Although the method of dry pressing has higher efficiency, the molded product has the problems of density difference and uneven microstructure, and it is difficult to form complex shapes and shaped products; cold isostatic pressing can obtain high density and high uniformity. The green body, but it is still difficult to form ceramic parts with complicated shapes, and the molding efficiency is low and manual operation is large. Although the injection molding can form a profiled product and achieve a near-net size, the molded body is liable to cause density unevenness and composition segregation, as well as low dimensional accuracy and product reliability, and the molding method requires manual operation. Drying efficiency is low. The biggest problem of hot die casting is that the production cycle is long and the efficiency is low. It takes tens of hours or even hundreds of hours to remove the organic binder such as paraffin, and the ceramic is prone to defects such as pores and cracks during the wax discharge process.

In view of the above situation, it is imperative to study and promote rapid moldless molding technology as soon as possible for China's backward ceramic industry. 3D printing technology is light curing molding technology (Stereo Lithography Appearance, abbreviated SLA), the principle is shown in Figure 1. The computer controls the laser beam of specific wavelength and intensity to scan on the xy plane, from point to line, from line to surface, to make the ceramic slurry selective. Curing, complete one level of drawing work, then the lifting table moves the height of one layer in the vertical direction, and then solidifies another layer, so that layers are stacked to form a ceramic body.

Summary of the invention

The invention aims to produce the tooth-shaped irregular ceramic with the prior art, the unevenness of the blank body, the dimensional accuracy of the product after sintering, the tooth shape is not good, and the like, and provide a tooth shape with good uniformity of the green body and high dimensional accuracy of the ceramic product. Method for preparing shaped ceramics.

To achieve the above object, the present invention employs the following technical solutions.

The preparation method of the tooth shaped ceramics comprises the following steps:

S1 preparation of slurry: weigh each component and mix well according to the following mass percentage, 20-75% ceramic powder, 10-70% premix, 0.1-5% photoinitiator, 0.1-5% dispersion A 0.1% to 5% surface modifier to obtain a slurry.

The premix liquid is composed of an organic solute and a solvent, the mass of the solvent being 20-85% of the mass of the premix liquid; the organic solute is acrylamide, dimethacrylate, methacrylamide, methacrylic acid 2 At least one of -hydroxyethyl ester and N-N'methylenebisacrylamide.

Preferably, the solvent is at least one of deionized water, glycerin, absolute ethanol and acetone.

Preferably, the ceramic powder is at least one of zirconia powder, alumina powder, and mullite powder. More preferably, the ceramic powder has a particle diameter of 0.1 to 5 μm; the ceramic powder has a bimodal distribution structure (that is, the ceramic powder has a wide particle size distribution) or is compounded by two particle sizes. Got it.

Preferably, the dispersing agent is at least one of sodium hexametaphosphate, sodium polyacrylate, ammonium polyacrylate, and PVP (polyvinylpyrrolidone).

Preferably, the photoinitiator used is ammonium persulfate, potassium persulfate, 2,4,6-trimethylbenzoyl, diphenylphosphine oxide or 2-hydroxy-2-methyl-1-phenyl-1 -acetone.

Preferably, the surfactant is stearic acid or a coupling agent.

Preferably, in the step of preparing the slurry, firstly, the ceramic powder and a part of the dispersing agent are uniformly mixed with ethanol to form a ceramic powder dispersion, which is reserved; the organic solute and the solvent are uniformly mixed to form a premix, and then to the premix. The ceramic powder dispersion, the remaining dispersant and the surface modifier are added, and the initial slurry is obtained by ball milling for 3-24 hours; the initial slurry is placed under a negative pressure environment and the initial slurry is stirred for 20-120 minutes to remove bubbles. The photoinitiator was further added to the initial slurry and uniformly mixed to prepare a slurry.

More preferably, the ball milling medium used in the above ball milling is alumina or zirconia, the shape of the ball milling medium is spherical or columnar, the diameter of the ball milling medium is 3 mm or 5 mm or 10 mm, and the ratio of the ball to ball is 2:1 or 3:1 or 6:1.

S2 molding: The slurry is placed in a photocuring molding apparatus, and the green body is drawn by the photocuring molding method according to the designed ceramic shape.

Preferably, the photocuring molding apparatus has a scanning speed of 800-3500 mm/s, a scanning mode of XYSTA, and a scanning pitch of 0.2-0.7 mm. More preferably, the wavelength λ of the light used in the photocuring molding method is 355 nm.

Then, the green body is sequentially subjected to a drying step, a degreasing step, and a sintering step to obtain a tooth-shaped shaped ceramic.

Preferably, the drying step is: drying the blank in a liquid desiccant for 5-36 h or drying the body with microwave for 5-36 h; and drying at a temperature of 25-60 °C.

When the body is liquid dried using a liquid desiccant, the preferred liquid desiccant is polyvinyl alcohol, polyacrylic acid or polyacrylamide. More preferably, after the green body is subjected to liquid drying treatment, the liquid desiccant on the surface of the green body is cleaned with a cleaning liquid; specifically, the green body may be placed in ethanol and ultrasonically cleaned.

Preferably, the degreasing step is: first performing vacuum degreasing or atmosphere protection degreasing treatment on the green body, and then performing air degreasing treatment on the green body.

The use of vacuum debinding or atmosphere protection debinding can reduce the rate of cracking of organic matter in the green body, thereby reducing defects such as cracking and foaming of the green body. The carbon remaining in the body due to vacuum debinding or atmosphere protection debinding can be removed by air debinding.

More preferably, the vacuum degreasing or atmosphere protection degreasing condition is: placing the blank in a vacuum debinding furnace or an inert gas/N ₂ protective debinding furnace at a rate of 0.1-5 ° C/min. Warm up to 300-1000 ° C and keep warm for 2-6h, and keep warm every 50-150 ° C for 0-60min; then, the blank is in the vacuum oven or inert gas / N ₂ protective rubber furnace Cool to room temperature. Further preferably, the negative pressure debinding furnace means that the degree of vacuum in the debinding furnace is greater than or equal to 0.09 MPa.

More preferably, the air degreasing condition is: placing the blank in a debinding furnace in an air atmosphere, raising the temperature to 300-1000 ° C at a rate of 5-8 ° C / min and holding for 2-3 h; The furnace was cooled to room temperature.

Preferably, the sintering step is carried out by placing the green body in a sintering furnace, raising the temperature to 1350-1550 ° C at a rate of 10-15 ° C / min and holding for 1-4 h, and then cooling the furnace to obtain a tooth shape. Shaped ceramics.

More preferably, the sintering furnace is a sintering furnace or a graphite electrode sintering furnace of a silicon molybdenum rod heating element.

Compared with the prior art, the beneficial effects of the present invention are: the present invention optimizes the composition and ratio of the slurry, and makes the slurry suitable for the photocuring molding method to draw the toothed ceramic body, which not only has high molding efficiency, but also has high molding efficiency. The ceramic particles in the green body are uniformly dispersed, and the shape and dimensional accuracy of the green body are high; and by controlling the process parameters in the degreasing and sintering steps, the green body is not deformed or cracked during the manufacturing process, and the compactness of the sintering is higher, and the toothed ceramics are more. The structure of the product is more uniform, the precision is higher, the surface finish is better, and the thickness of the toothed ceramic product can be greater than 8 mm, thereby improving the reliability of the ceramic product. The invention adopts a two-step degreasing method combining vacuum/atmosphere protection degreasing and air degreasing, which not only can significantly improve the degreasing efficiency, but also shortens the degreasing time from 48-60h to 8-20h of the existing method; The problem of deformation, cracking, foaming, etc. caused by too fast degreasing rate or excessive cracking rate of organic matter in the green body, and vacuum/atmosphere protection after degreasing combined with air debinding, the vacuum can be discharged from the blank. The atmosphere protects the residual carbon from degreasing.

DRAWINGS

1 is a schematic view showing the working principle of a photocuring molding apparatus;

Figure 2 is a plan view showing the target structure of the toothed ceramic product in each embodiment;

Figure 3 is a cross-sectional view showing the target structure of the toothed ceramic product in each embodiment;

Figure 4 is a finished view of the toothed ceramic product prepared in Example 2;

Figure 5 is an SEM image of a toothed ceramic product prepared in Example 2.

detailed description

In order to more fully understand the technical content of the present invention, the technical solutions of the present invention will be further described and illustrated below in conjunction with specific embodiments.

In the following embodiments, the rapid prototyping data conforming to the target structure for the photocuring molding apparatus is produced according to the prior art before the toothed ceramic product is produced, especially before the slurry is formed into a blank by a photocuring molding method. The rapid prototyping data file is imported into the control program of the photocuring molding equipment and is ready for use. Specifically: the software UG is used for 3D solid modeling to obtain the model of the toothed ceramic; the model is imported into the rapid prototyping assistant software Magics to generate support and slice processing, and then the rapid prototyping data file is output, and the rapid prototyping data file is imported. In the control program of the light curing molding equipment. The target structure of the toothed shaped ceramic product prepared in the following examples is a gear-shaped ceramic part having a maximum diameter of 20 mm (shown as A in Fig. 3) and a thickness of 8 mm (shown as H in Fig. 3). There are 20 teeth evenly distributed on the edge, as shown in Figures 2 and 3. In other embodiments, the corresponding rapid prototyping data can be made according to the structure of the actual toothed ceramic product, and the structure of the toothed ceramic product is not limited to the structure shown in the following embodiments.

Example 1

This embodiment provides a method for preparing a tooth-shaped shaped ceramic, and the specific steps are as follows:

(1) Preparation of slurry

Premix: weigh 650g deionized water and 100g glycerol as solvent; weigh 234.3g acrylamide and 15.6g respectively N-N' methylene bis acrylamide is used as an organic solute. The organic solute and the solvent were uniformly mixed, and the organic solute was completely dissolved to obtain 1000 g of a yellowish transparent premix.

The above premixed liquid was taken, and 3 g of ammonium polyacrylate and 1000 g of α-alumina (ceramic powder having a bimodal distribution structure; 0.1 μm ≤ particle diameter ≤ 0.5 μm, purity of 99.99%) and 1 g were weighed, respectively. 2-Hydroxy-2-methyl-1-phenyl-1-propanone (photoinitiator 1173), 12 g stearic acid (surface modifier).

Pre-made ceramic powder dispersion: The ceramic powder, ethanol, and part of the dispersant are ball milled in a planetary ball mill for 6 hours to form a ceramic powder dispersion. The ball milling medium used in the ball milling is alumina, the shape of the ball milling medium is spherical, the diameter of the ball milling medium is 3 mm, and the ratio of the ball to the ball is 2:1.

Re-slurry: adding ceramic powder dispersion, residual dispersant and surface modifier to the premixed liquid, ball milling for 12h to obtain initial slurry; placing the primary slurry under negative pressure and stirring the initial slurry for 60min In order to remove the bubbles, a photoinitiator is finally added to the primary slurry and stirred uniformly to prepare a slurry.

(2) Forming

The slurry was placed in a photocuring molding apparatus, and the green body was drawn by a photocuring molding apparatus (wavelength: 355 nm) in a designed ceramic shape. Among them, the scanning speed of the photocuring molding apparatus is set to 2000 mm/s, the scanning pitch is 0.5 mm, and the scanning mode is XYSTA. The blank is then removed and the uncured slurry on the surface of the blank is cleaned.

(3) Drying

The green body was dried in polyethylene glycol having a molecular weight of 400 for 36 hours, and the drying temperature was 25 ° C. Then, the green body was placed in absolute ethanol for ultrasonic cleaning to remove the liquid desiccant on the surface of the green body, and then the green body was removed. The body is dried in an oven.

(4) Degreasing

Firstly, the blank body is vacuum degreased or atmosphere degreased: the blank body is placed in a rubberizing furnace with a vacuum degree of ≥0.09 MPa, and the temperature is raised to 600 ° C at a rate of 2 ° C/min and kept for 2 h, and every 100 times during the heating process The temperature is maintained for 20 min at ° C; the vacuum of the debinding furnace is maintained, and the green body is cooled to room temperature with the debinding furnace.

The body is then degreased by air: the body is placed in a degassing furnace in an air atmosphere, heated to 600 ° C at a rate of 3 ° C / min and held for 2 h; then heated to 1000 ° C at a rate of 15 ° C / min and The temperature was kept for 30 minutes, and then the body was cooled to room temperature with the furnace.

(5) Sintering

The green body was placed in a sintering furnace (sintering furnace of a silicon molybdenum rod heating element) in an air atmosphere, and heated to 1350 ° C at a rate of 15 ° C / min and held for 1 h to obtain a tooth-shaped shaped ceramic.

The toothed shaped ceramic prepared in this example had a density of 3.80 g/cm ³ and a Vickers hardness of 15.6 GPa. The structure and size of the tooth-shaped shaped ceramic prepared in this embodiment are basically the same as the target structure, the shrinkage is small, the shape variable is small, negligible, the shape of the teeth on the rim is intact, and the shape and dimensional precision of the finished product are high.

Example 2

(1) Preparation of slurry

Premix: weigh 760g deionized water and 140g glycerol as solvent; weigh 290g acrylamide and 10g respectively N-N' methylene bis acrylamide is used as an organic solute. The organic solute and the solvent were uniformly mixed, and the organic solute was completely dissolved to obtain 1200 g of a yellowish transparent premix.

Take the above premix and weigh 14.4g PVP and 1800g respectively. --alumina (ceramic powder, with bimodal distribution structure; 0.1μm ≤ particle size ≤ 0.5μm, purity is 99.99%), 12g 2-Hydroxy-2-methyl-1-phenyl-1-propanone (photoinitiator 1173), 18 g stearic acid (surface modifier).

Pre-made ceramic powder dispersion: The ceramic powder, ethanol, and part of the dispersant are ball-milled in a planetary ball mill for 3 hours to form a ceramic powder dispersion. The ball milling medium used in the ball milling is zirconia, the shape of the ball milling medium is columnar, the diameter of the ball milling medium is 5 mm, and the ratio of the ball to the ball is 6:1.

Re-slurry: adding ceramic powder dispersion, residual dispersant and surface modifier to the premixed liquid, ball milling for 24h to obtain the initial slurry; placing the primary slurry under negative pressure and stirring the initial slurry for 60min In order to remove the bubbles, a photoinitiator is finally added to the primary slurry and stirred uniformly to prepare a slurry.

(2) Forming

The slurry was placed in a photocuring molding apparatus, and the green body was drawn by a photocuring molding apparatus (wavelength: 355 nm) in a designed ceramic shape. Among them, the scanning speed of the photocuring molding apparatus is set to 1000 mm/s, the scanning pitch is 0.3 mm, and the scanning mode is XYSTA. The blank is then removed and the uncured slurry on the surface of the blank is cleaned.

(3) Drying

The green body was placed in a microwave oven for 5 hours, the drying temperature was 60 ° C, and then the body was placed in an oven for drying.

(4) Degreasing

Firstly, vacuum degrease or atmosphere protection degreasing of the blank: the blank is placed in a rubberizing furnace with a vacuum degree of ≥0.09 MPa, heated to 700 ° C at a rate of 3 ° C/min and kept for 2 h, and every 100 times during the heating process The temperature is maintained for 30 min at ° C; the vacuum of the debinding furnace is maintained, and the green body is cooled to room temperature with the debinding furnace.

The body is then degreased by air: the body is placed in a debinding furnace in an air atmosphere, heated to 700 ° C at a rate of 5 ° C / min and held for 3 h; then heated to 1100 ° C at a rate of 10 ° C / min and The temperature was kept for 30 minutes, and then the body was cooled to room temperature with the furnace.

(5) Sintering

The green body was placed in a sintering furnace (graphite electrode sintering furnace) in an air atmosphere, and heated to 1550 ° C at a rate of 10 ° C / min and kept for 3 hours to obtain a tooth-shaped shaped ceramic.

The denture-shaped ceramic prepared in this embodiment has a density of 3.97 g/cm. ³The Vickers hardness is 21 GPa. The structure of the tooth-shaped shaped ceramic prepared in this embodiment is shown in FIG. 4. The structure and size of the tooth-shaped shaped ceramic are basically the same as the target structure, the shrinkage is small, the shape variable is small, and the shape of the tooth on the rim is negligible. They are all intact and the shape and dimensional accuracy of the finished product is high. The microstructure of the tooth-shaped shaped ceramic prepared in this embodiment is shown in FIG. 5 (SEM image). It can be seen from FIG. 5 that the microstructure of the tooth-shaped shaped ceramic prepared in this embodiment is uniform and compact, and the average grain size is about 1.5. Μm, almost no pores and impurities, the toothed shaped ceramic has high strength and high hardness.

Example 3

The embodiment provides a method for preparing a tooth-shaped shaped ceramic. The specific steps are basically the same as those of the first embodiment. The difference is that the parameters set by the light curing molding device in the molding step are different, as follows: setting the light curing molding device The scanning speed is 800 mm/s, the scanning pitch is 0.2 mm, and the scanning mode is XYSTA.

The toothed shaped ceramic prepared in this example had a density of 3.91 g/cm ³ and a Vickers hardness of 17.7 GPa. The structure and size of the tooth-shaped shaped ceramic prepared in this embodiment are basically the same as the target structure, the shrinkage is small, the shape variable is small, negligible, the shape of the teeth on the rim is intact, and the shape and dimensional precision of the finished product are high.

Example 4

The embodiment provides a method for preparing a tooth-shaped shaped ceramic. The specific steps are basically the same as those of the first embodiment. The difference is that the parameters set by the light curing molding device in the molding step are different, as follows: setting the light curing molding device The scanning speed is 3500 mm/s, the scanning pitch is 0.7 mm, and the scanning mode is XYSTA.

The toothed shaped ceramic prepared in this example had a density of 3.85 g/cm ³ and a Vickers hardness of 17.1 GPa. The structure and size of the tooth-shaped shaped ceramic prepared in this embodiment are basically the same as the target structure, the shrinkage is small, the shape variable is small, negligible, the shape of the teeth on the rim is intact, and the shape and dimensional precision of the finished product are high.

Example 5

The embodiment provides a method for preparing a tooth-shaped shaped ceramic. The specific steps are basically the same as those of the first embodiment. The difference is that the parameters set by the light curing molding device in the molding step are different, as follows: setting the light curing molding device The scanning speed is 2500 mm/s, the scanning pitch is 0.4 mm, and the scanning mode is XYSTA.

The toothed shaped ceramic prepared in this example had a density of 3.92 g/cm ³ and a Vickers hardness of 17.9 GPa. The structure and size of the tooth-shaped shaped ceramic prepared in this embodiment are basically the same as the target structure, the shrinkage is small, the shape variable is small, negligible, the shape of the teeth on the rim is intact, and the shape and dimensional precision of the finished product are high.

Example 6

(1) Preparation of slurry

Premix: weigh 520g deionized water and 80g glycerol as solvent; weigh 180g acrylamide and 20g respectively N-N' methylene bis acrylamide is used as an organic solute. The organic solute and the solvent were uniformly mixed, and the organic solute was completely dissolved to obtain 800 g of a yellowish transparent premix.

Take the above premix and weigh 8g of ammonium polyacrylate, 1000g --alumina (ceramic powder, with bimodal distribution structure; 0.1μm ≤ particle size ≤ 0.5μm, purity is 99.99%), 1g 2-Hydroxy-2-methyl-1-phenyl-1-propanone (photoinitiator 1173), 10 g stearic acid (surface modifier).

(2) Forming

The slurry was placed in a photocuring molding apparatus, and the green body was drawn by a photocuring molding apparatus (wavelength: 355 nm) in a designed ceramic shape. Among them, the scanning speed of the photocuring molding apparatus is set to 500 mm/s, the scanning pitch is 0.5 mm, and the scanning mode is XYSTA. The blank is then removed and the uncured slurry on the surface of the blank is cleaned.

(3) Drying

The green body was dried in polyethylene glycol having a molecular weight of 400 for 12 hours, and the drying temperature was 40 ° C. Then, the green body was placed in absolute ethanol for ultrasonic cleaning to remove the liquid desiccant on the surface of the green body, and then the blank was removed. The body is dried in an oven.

(4) Degreasing

Firstly, vacuum degrease or atmosphere protection degreasing of the blank: the blank is placed in a rubberizing furnace with a vacuum degree of ≥0.09 MPa, and the temperature is raised to 600 ° C at a rate of 2 ° C/min and kept for 1 h, and every 120 degrees during the heating process The temperature is maintained for 20 min at ° C; the vacuum of the debinding furnace is maintained, and the green body is cooled to room temperature with the debinding furnace.

The body is then degreased by air: the body is placed in a degassing furnace in an air atmosphere, heated to 600 ° C at a rate of 5 ° C / min and held for 3 h; then heated to 1000 ° C at a rate of 15 ° C / min and The temperature was kept for 30 minutes, and then the body was cooled to room temperature with the furnace.

(5) Sintering

The green body was placed in a sintering furnace (graphite electrode sintering furnace) in an air atmosphere, and heated to 1400 ° C at a rate of 15 ° C / min and held for 1 h to obtain a tooth-shaped shaped ceramic.

The toothed shaped ceramic prepared in this example had a density of 3.78 g/cm ³ and a Vickers hardness of 15.5 GPa.

The structure and size of the tooth-shaped shaped ceramic prepared in this embodiment are basically the same as the target structure, and the shrinkage is small, achieving higher density and hardness. However, since the scanning speed during photocuring is too small, the powder particles are greatly scattered by the laser during the curing process, resulting in a high and low undulation of the surface of the sample, and the precision is too low, so that a highly accurate tooth-shaped shaped member cannot be prepared.

Example 7

(1) Preparation of slurry

Premix: 600g deionized water and 80g glycerol as solvent; weigh 750g acrylamide and 50g respectively N-N' methylene bis acrylamide is used as an organic solute. The organic solute and the solvent were uniformly mixed, and the organic solute was completely dissolved to obtain 800 g of a yellowish transparent premix.

Take the above premix and weigh 4.8g of ammonium polyacrylate, 800g --alumina (ceramic powder, with bimodal distribution structure; 0.1μm ≤ particle size ≤ 0.5μm, purity is 99.99%), 1g 2-Hydroxy-2-methyl-1-phenyl-1-propanone (photoinitiator 1173), 15 g stearic acid (surface modifier).

Re-slurry: adding ceramic powder dispersion, residual dispersant and surface modifier to the premixed liquid, ball milling for 16h to obtain initial slurry; placing the primary slurry under negative pressure and stirring the initial slurry for 40min In order to remove the bubbles, a photoinitiator is finally added to the primary slurry and stirred uniformly to prepare a slurry.

(2) Forming

The slurry was placed in a photocuring molding apparatus, and the green body was drawn by a photocuring molding apparatus (wavelength: 355 nm) in a designed ceramic shape. Among them, the scanning speed of the photocuring molding apparatus is set to 4000 mm/s, the scanning pitch is 0.5 mm, and the scanning mode is XYSTA.

Since the scanning speed in the present embodiment is too large, the surface exposure amount of the slurry is small, and the slurry is difficult in solidification molding, and it is impossible to print a highly accurate tooth-shaped shaped member.

Example 8

(1) Preparation of slurry

Premix: weigh 360g deionized water and 90g glycerol as solvent; weigh 140g acrylamide and 10g respectively N-N' methylene bis acrylamide is used as an organic solute. The organic solute and the solvent were uniformly mixed, and the organic solute was completely dissolved to obtain 600 g of a yellowish transparent premix.

Take the above premix and weigh 15g sodium polyacrylate, 1000g --alumina (ceramic powder, with bimodal distribution structure; 0.1μm ≤ particle size ≤ 0.5μm, purity is 99.99%), 1g 2-Hydroxy-2-methyl-1-phenyl-1-propanone (photoinitiator 1173), 12 g stearic acid (surface modifier).

(2) Forming

The slurry was placed in a photocuring molding apparatus, and the green body was drawn by a photocuring molding apparatus (wavelength: 355 nm) in a designed ceramic shape. Among them, the scanning speed of the photocuring molding apparatus is set to 1500 mm/s, the scanning pitch is 1.0 mm, and the scanning mode is XYSTA.

In this embodiment, since the scanning pitch is large, and the curing width of the slurry is smaller than the scanning pitch, the adjacent two curing lines cannot be bridged, and the embryo body cannot be printed.

Example 9

(1) Preparation of slurry

Take the above premix and weigh 8g of ammonium polyacrylate, 1000g --alumina (ceramic powder, with bimodal distribution structure; 0.1μm ≤ particle size ≤ 0.5μm, purity is 99.99%), 1g 2-Hydroxy-2-methyl-1-phenyl-1-propanone (photoinitiator 1173), 15 g of oleic acid (coupling agent, surface modifier).

(2) Forming

The slurry was placed in a photocuring molding apparatus, and the green body was drawn by a photocuring molding apparatus (wavelength: 355 nm) in a designed ceramic shape. Among them, the scanning speed of the photocuring molding apparatus is set to 1500 mm/s, the scanning pitch is 0.1 mm, and the scanning mode is XYSTA. The blank is then removed and the uncured slurry on the surface of the blank is cleaned.

(3) Drying

(4) Degreasing

The body is then degreased by air: the body is placed in a degassing furnace in an air atmosphere, heated to 650 ° C at a rate of 3 ° C / min and held for 3 h; then heated to 1000 ° C at a rate of 10 ° C / min and The temperature was kept for 30 minutes, and then the body was cooled to room temperature with the furnace.

(5) Sintering

The green body was placed in a sintering furnace in an air atmosphere, and heated to 1500 ° C at a rate of 15 ° C / min and held for 1 h to obtain a tooth-shaped shaped ceramic.

The tooth-shaped shaped ceramic prepared in this embodiment has a density of 3.80 g/cm ³ and a Vickers hardness of 15.0 GPa. The structure and size of the tooth-shaped shaped ceramic prepared in this embodiment are substantially the same as the target structure, and the shrinkage is small, and the ratio is small. High density and hardness. However, during the experiment, the scanning pitch is too small. During the curing process, the curing thickness of the overlapping curing lines of the adjacent curing lines is greater than the thickness of the single layer curing, resulting in uneven surface of the sample, high and low undulations, and high-precision toothed ceramics cannot be produced.

In other embodiments, the organic solute comprising the premix may also be in the group consisting of acrylamide, dimethacrylate, methacrylamide, 2-hydroxyethyl methacrylate and N-N'methylenebisacrylamide. At least one. The solvent constituting the premix may also be at least one of deionized water, glycerin, absolute ethanol, and acetone.

In other embodiments, the ceramic powder may also be at least one of zirconia powder, alumina powder and mullite powder; the particle size of the ceramic powder may also be in the range of 0.1-5 μm, except for the ceramic powder. It is a powder having a bimodal distribution structure (that is, a ceramic powder having a wide particle size distribution), and may also be obtained by compounding powders of two particle sizes.

In other embodiments, the dispersing agent may also be at least one of sodium hexametaphosphate, sodium polyacrylate, ammonium polyacrylate, and PVP; the photoinitiator may also be ammonium persulfate, potassium persulfate, 2, 4, 6 - Trimethylbenzoyl, diphenylphosphine oxide or 2-hydroxy-2-methyl-1-phenyl-1-propanone. The surfactant may also be other coupling agents or stearic acid.

The above description is only for the purpose of further illustrating the technical content of the present invention in order to facilitate the understanding of the reader, but the embodiment of the present invention is not limited thereto, and any technology extension or re-creation according to the present invention is subject to Protection of the invention.

Claims

A method for preparing a tooth shaped shaped ceramic, comprising the steps of:

S1 preparation of slurry: weigh each component and mix well according to the following mass percentage, 20-75% ceramic powder, 10-70% premix, 0.1-5% photoinitiator, 0.1-5% dispersion a 0.1-5% surface modifier to obtain a slurry;

The premix liquid is composed of an organic solute and a solvent, the mass of the solvent being 20-85% of the mass of the premix liquid; the organic solute is acrylamide, dimethacrylate, methacrylamide, methacrylic acid 2 At least one of -hydroxyethyl ester and N-N'methylenebisacrylamide;

S2 molding: the slurry is placed in a photocuring molding apparatus, and the green body is drawn by the photocuring molding method according to the designed ceramic shape;

Then, the green body is sequentially subjected to a drying step, a degreasing step, and a sintering step to obtain a tooth-shaped shaped ceramic.
The method for preparing a tooth-shaped shaped ceramic according to claim 1, wherein in the forming step, the scanning speed of the photo-curing device is 800-3500 mm/s, the scanning mode is XYSTA, and the scanning pitch is 0.2- 0.7mm.
The method for preparing a tooth-shaped shaped ceramic according to claim 1, wherein the drying step comprises: drying the blank in a liquid desiccant for 5-36 hours or drying the body with microwave for 5-36 hours; drying The temperature is 25-60 ° C.
The method for preparing a tooth-shaped shaped ceramic according to claim 1, wherein the degreasing step is: first performing vacuum degreasing or atmosphere protection degreasing treatment on the green body, and then performing air degreasing treatment on the green body.
The method for preparing a toothed shaped ceramic according to claim 4, wherein the condition of the vacuum degreasing or atmosphere protection degreasing is: placing the blank in a vacuum oven or inert gas/N2 protection In the rubberizing furnace, the temperature is raised to 300-1000 ° C at a rate of 0.1-5 ° C / min and kept for 2-6 h, and the temperature is maintained at 50-150 ° C for 0-60 min during the heating process; then, the blank is under negative pressure. Cool to room temperature in a degreaser or in an inert gas/N2 protected degreaser.
The method for preparing a tooth-shaped shaped ceramic according to claim 4, wherein the air degreasing condition is: placing the blank in a debinding furnace in an air atmosphere at a rate of 5-8 ° C / min The temperature was raised to 300-1000 ° C and held for 2-3 h; then the body was cooled to room temperature with the furnace.
The method for preparing a toothed shaped ceramic according to claim 1, wherein the sintering step is carried out by placing the body in a sintering furnace and raising the temperature to 1350 at a rate of 10-15 ° C/min. The toothed shaped ceramic was prepared by heating at 1550 ° C for 1-4 h and then cooling with the furnace.
The method for preparing a toothed shaped ceramic according to claim 1, wherein in the step of preparing the slurry, firstly, the ceramic powder and a part of the dispersing agent are uniformly mixed with ethanol to form a ceramic powder dispersion, and the mixture is prepared. ;

The organic solute and the solvent are uniformly mixed to form a premixed liquid, and then the ceramic powder dispersion liquid, the surface modifier and the remaining dispersing agent are added to the premixed liquid, and ball milled for 3-24 hours to obtain a primary slurry; Under the negative pressure environment, the initial slurry was stirred for 20-120 min to remove the bubbles, and then the photoinitiator was added to the primary slurry and uniformly mixed to prepare a slurry.
The method of producing a toothed shaped ceramic according to claim 1, wherein the ceramic powder is at least one of zirconia powder, alumina powder, and mullite powder.
The method of producing a toothed shaped ceramic according to claim 1, wherein the ceramic powder has a particle diameter of 0.1 to 5 μm.