CN111807823B

CN111807823B - Alumina ceramic and preparation method thereof

Info

Publication number: CN111807823B
Application number: CN202010517344.5A
Authority: CN
Inventors: 甘志俭; 程银兵; 杨斌; 庄志杰
Original assignee: Gemch Material Technology Suzhou Co ltd
Current assignee: Gemch Material Technology Suzhou Co ltd
Priority date: 2020-06-09
Filing date: 2020-06-09
Publication date: 2022-05-24
Anticipated expiration: 2040-06-09
Also published as: WO2021248813A1; CN111807823A

Abstract

The invention discloses an alumina ceramic and a preparation method thereof, wherein the method comprises the following steps: preparing alumina powder into slurry to obtain alumina slurry with the particle size D90 less than or equal to 0.8 mu m; drying the alumina slurry to obtain alumina fine powder; the content of alumina in the alumina powder is more than or equal to 99 wt%; heating and melting the photosensitive resin, the first dispersant and the lubricant, adding the alumina fine powder and the ultraviolet absorber, uniformly mixing, and then carrying out vacuum pumping treatment to obtain alumina photocuring slurry; 3D printing and molding the alumina photocuring slurry to obtain an alumina ceramic blank; degreasing and sintering the aluminum oxide ceramic blank at normal pressure to obtain aluminum oxide ceramic; the conditions of normal pressure degreasing sintering are as follows: heating to 550-650 ℃ at the rate of (0.2-1) DEG C/min, preserving heat for 6-10 h, then heating to 1200-1400 ℃ at the rate of (1-5) DEG C/min, and preserving heat for 5-8 h. The alumina ceramic prepared by the method has high density and good mechanical property, and can meet the requirements of semiconductor equipment on ceramic materials.

Description

Alumina ceramic and preparation method thereof

Technical Field

The invention relates to the technical field of ceramics, in particular to alumina ceramics and a preparation method thereof.

Background

The content of alumina in the high-purity alumina powder is more than 99 wt%, and the high-purity alumina powder has the characteristics of uniform particle size, easy dispersion, stable chemical property and the like, has optical, electric, magnetic, thermal and mechanical properties which are incomparable with those of common alumina powder (the content of alumina is more than 80 wt%), and is widely applied as a plasma erosion resistant material in etching manufacturing equipment of semiconductors and liquid crystal display screens. At present, the accelerated development of the domestic semiconductor industry inevitably leads to the increase of the demand of the alumina precision ceramics for the semiconductor.

The existing alumina ceramics have different manufacturing methods, wherein a large number of methods used for industrial production adopt the processes of isostatic pressing, high-temperature sintering, grinding, polishing and the like, and the method is mainly suitable for alumina ceramics with the purity of 95 percent, but is not suitable for other alumina ceramics, such as alumina ceramics with the purity of 99 percent. The alumina ceramic prepared by the method has the problems of lower density, low mechanical strength of the ceramic and the like, and can not meet the requirements of semiconductor equipment on the alumina ceramic.

Disclosure of Invention

Accordingly, there is a need for an alumina ceramic having improved compactness and mechanical properties, and a method for preparing the same. In one aspect of the present invention, there is provided a method for preparing an alumina ceramic, comprising the steps of:

Preparing alumina powder into slurry to obtain alumina slurry with the particle size D90 of less than or equal to 0.8 mu m; drying the alumina slurry to obtain alumina fine powder; the content of alumina in the alumina powder is more than or equal to 99 wt%;

heating and melting the photosensitive resin, the first dispersant and the lubricant, adding the alumina fine powder and the ultraviolet absorber, uniformly mixing, and then carrying out vacuum pumping treatment to obtain alumina photocuring slurry;

3D printing and molding the alumina photocuring slurry to obtain an alumina ceramic blank;

degreasing and sintering the aluminum oxide ceramic blank under normal pressure to obtain aluminum oxide ceramic;

the conditions of the normal-pressure degreasing sintering are as follows: heating to 550-650 ℃ at the rate of (0.2-1) DEG C/min, preserving heat for 6-10 h, then heating to 1200-1400 ℃ at the rate of (1-5) DEG C/min, and preserving heat for 5-8 h.

The preparation method comprises the steps of taking high-purity alumina powder as a raw material, performing ball milling to obtain alumina slurry with D90 being less than or equal to 0.8 mu m, drying to obtain nano-scale high-activity spherical alumina fine powder, preparing photocuring slurry, performing 3D printing forming to prepare a blank, meeting the requirements of semiconductor equipment on the shape and size precision of ceramic, and performing normal pressure degreasing and low-temperature sintering to prepare the alumina ceramic. The alumina fine powder has small grain size and high sintering activity, so that the sintering can be completed within 1400 ℃, the alumina grains sintered at low temperature do not have abnormal mutation, the grain size is uniform, the alumina ceramic with high density and high mechanical property can be prepared, and the requirement of semiconductor equipment on the alumina ceramic is met.

Meanwhile, the alumina ceramic blank body of the method can be sintered under normal pressure within 1400 ℃, so that the sintering requirement can be met by using a common normal-pressure sintering furnace, the equipment cost investment can be reduced, the sintering temperature is low, and the energy consumption cost can be greatly reduced.

In some embodiments, the alumina powder contains more than or equal to 99.99 percent of alumina, D50 is 0.3-0.6 μm, and BET is 10m²/g～20m²/g。

In some embodiments, the conditions of the atmospheric degreasing sintering are as follows: heating to 600 ℃ at the speed of 0.2-1 ℃/min, preserving heat for 6-10 h, then heating to 1200-1400 ℃ at the speed of 2-5 ℃/min, and preserving heat for 6-8 h.

In some embodiments, the alumina particles, the photosensitive resin, the first dispersant, the lubricant, and the ultraviolet light absorber are 80 to 85 parts, 5 to 10 parts, 1 to 10 parts, 2 to 10 parts, and 1 to 5 parts, respectively, by weight of the alumina photocuring paste.

In some of these embodiments, the photosensitive resin is selected from at least one of epoxy acrylic, polyurethane acrylic, and polyester acrylic.

In some of these embodiments, the first dispersant is selected from at least one of stearic acid, oleic acid, and polyethylene glycol.

In some of these embodiments, the lubricant is selected from at least one of paraffin and glycerol.

In some of these embodiments, the ultraviolet light absorber is selected from at least one of phenyl salicylate, 2, 4-dihydroxybenzophenone, and resorcinol monobenzoate.

In some of the embodiments, the step of preparing the alumina powder into the slurry comprises: mixing water, a second dispersing agent and the high-purity alumina powder, and then ball-milling for 2-6 h, wherein the weight ratio of the high-purity alumina powder to the water is (4-7) to (3-6), the weight of the second dispersing agent is 1-3% of that of the high-purity alumina powder, and the second dispersing agent is an organic solvent.

In some of these embodiments, the second dispersant is selected from at least one of polyvinyl alcohol, polyethylene glycol, and polystyrene.

In some embodiments, the drying is performed by spray drying, and the inlet air temperature of the drying is 250-350 ℃, the outlet air temperature is 100-150 ℃, and the rotation speed is 9000-12000 rpm.

In some embodiments, the method further comprises the step of grinding and polishing the aluminum oxide ceramic after the atmospheric degreasing sintering, so as to control the surface roughness Ra of the aluminum oxide ceramic after grinding and polishing to be less than or equal to 0.1 μm.

In another aspect of the present invention, an alumina ceramic is provided, which is prepared by the above alumina ceramic preparation method.

Drawings

Fig. 1 is a schematic view of a method for producing an alumina ceramic according to an embodiment.

Detailed Description

To facilitate an understanding of the invention, the invention will now be described more fully with reference to the accompanying drawings. Preferred embodiments of the present invention are shown in the drawings. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.

The existing method for forming the alumina ceramic product mainly adopts the methods of dry pressing, grouting, extruding, cold isostatic pressing, injecting, tape casting, hot pressing, hot isostatic pressing and the like, and the forming methods have the problem that blanks with complex shapes and high dimensional precision are difficult to prepare. Moreover, the preparation of ceramics by using common alumina powder requires sintering in a high-temperature furnace above 1700 ℃, which not only has higher requirements on the performance of the sintering furnace and high energy consumption, but also is not suitable for semiconductor equipment because the common alumina powder has large particle size and low sintering activity, alumina ceramics with high density are difficult to obtain during high-temperature sintering, and the size of partial crystal grains is too large, which causes the mechanical strength of the ceramics to be low and the ceramics to crack easily.

Therefore, the invention takes high-purity alumina as a raw material, combines a 3D printing and forming method to prepare a blank, and then carries out low-temperature normal-pressure sintering at the temperature of 1400 ℃ or below to prepare the alumina ceramic with high density, fine grains and high mechanical property, and can meet the requirements of semiconductor equipment on the alumina ceramic.

One embodiment of the present invention provides a method for producing an alumina ceramic sintered body, as shown in fig. 1, including the following steps S10 to S18.

S10, preparing the alumina powder into slurry and drying to obtain alumina fine powder.

Specifically, alumina powder with the alumina content of more than or equal to 99 wt% is prepared into slurry to obtain alumina slurry with the particle size D90 of less than or equal to 0.8 mu m, and then the alumina slurry is dried to obtain alumina fine powder.

In some embodiments, the alumina powder has an alumina content of 99.99 wt% or more, a D50 content of 0.3 to 0.6 μm, and a BET (specific surface area) content of 10m²/g～20m²/g。

D90 denotes the particle size with a cumulative particle distribution of 90%, i.e. the volume fraction of particles smaller than this accounts for 90% of the total particles. D50 represents the particle size with a cumulative particle distribution of 50%, also known as median. The D50 value of 0.3 to 0.6 μm means that the volume of particles having a particle diameter of 0.3 to 0.6 μm in the alumina powder accounts for 50%, and the total volume of particles having a particle diameter of less than 0.3 μm and more than 0.6 μm accounts for 50%.

In some embodiments, the step of slurrying the alumina powder is: and mixing a ball milling medium, a second dispersing agent and alumina powder, and then ball milling for 2-6 h, wherein the weight ratio of the alumina powder to the ball milling medium is (4-7) to (3-6), and the weight of the second dispersing agent is 1-3% of that of the high-purity alumina powder.

Further, the ball milling medium is selected from water and volatile organic solvents; preferably, the ball milling medium is water. The second dispersant is selected from at least one of polyvinyl alcohol, polyethylene glycol and polystyrene; preferably, the second dispersant is polyvinyl alcohol.

In some embodiments, the milling media and the second dispersant are mixed and stirred, and then high purity alumina powder is added and stirred into slurry, and then ball milling is performed in a high speed nano-mill. Wherein the high-purity alumina powder accounts for 40-70% of the total weight of the high-purity alumina powder and the ball-milling medium, and the weight of the second dispersing agent is 1-3% of the weight of the high-purity alumina powder. Water is used as a ball milling medium, alumina balls are used as grinding balls, the ball milling time is 2-6 h, and the particle size D90 of the slurry obtained after ball milling is less than or equal to 0.8 mu m.

In some embodiments, a centrifugal spray dryer is used for spray drying, the air inlet temperature of the centrifugal drying of the spray drying is 250-350 ℃, the air outlet temperature is 100-150 ℃, and the atomization rotating speed is 9000-12000 rpm, so that the nanometer spherical alumina fine powder with high bulk density is prepared.

And S12, melting the organic grease, adding the alumina fine powder and the ultraviolet absorber, uniformly mixing, and carrying out vacuum treatment to obtain the alumina photocuring slurry.

Specifically, after the photosensitive resin, the first dispersant and the lubricant are heated and melted, the alumina fine powder and the ultraviolet absorber are added, and after uniform mixing, vacuum pumping treatment is carried out to obtain the alumina photocuring slurry.

In some embodiments, the alumina light-curing paste comprises 80 to 85 parts by weight of alumina fine powder, 5 to 10 parts by weight of photosensitive resin, 1 to 10 parts by weight of first dispersant, 2 to 10 parts by weight of lubricant, and 1 to 5 parts by weight of ultraviolet absorber.

In some embodiments, the photosensitive resin is selected from at least one of polyacrylic, epoxy acrylic, polyurethane acrylic, and polyester acrylic; the first dispersant is at least one selected from stearic acid, oleic acid and polyethylene glycol; the lubricant is selected from paraffin and/or glycerol; the ultraviolet light absorber is at least one selected from phenyl salicylate, 2, 4-dihydroxy benzophenone and resorcinol monobenzoate.

Preferably, the photosensitive resin is polyacrylic resin, the first dispersant is stearic acid, the lubricant is paraffin, and the ultraviolet light absorber is phenyl salicylate.

Further, melting the polyacrylic resin at 190-200 ℃, cooling to 100-120 ℃, adding stearic acid, cooling to 80-100 ℃ after melting, adding paraffin wax for melting, continuously adding the alumina fine powder in a stirring state after the organic ester is completely melted, adding the ultraviolet absorber after the addition is finished, continuously stirring for 2-4 h until the slurry is uniformly mixed, and then carrying out vacuum pumping treatment to eliminate bubbles in the slurry, thus obtaining the alumina photocuring slurry. Therefore, the defects of holes and the like generated during the molding of the alumina light-cured slurry can be avoided.

And S14, 3D printing and forming to obtain an aluminum oxide ceramic blank.

Specifically, the alumina photocuring slurry prepared in step S12 is printed and molded by a 3D printer according to a design drawing to obtain an alumina ceramic blank.

The 3D printing molding is adopted, the requirements of semiconductor equipment on shape compounding and high size precision can be met, and the production efficiency is high.

And S16, degreasing and sintering the aluminum oxide ceramic blank at normal pressure to obtain the aluminum oxide ceramic.

Specifically, the conditions of the atmospheric degreasing sintering are as follows: heating to 550-650 ℃ at the rate of (0.2-1) DEG C/min, preserving heat for 6-10 h, then heating to 1200-1400 ℃ at the rate of (1-5) DEG C/min, and preserving heat for 5-8 h.

The invention takes the nano-scale high-purity alumina powder as the raw material, can finish degreasing sintering at 1400 ℃ and below, can avoid the problems of reduced mechanical strength and easy cracking of ceramic bodies caused by oversize of partial crystal grains in the ceramic due to overhigh sintering temperature (such as 1600-1700 ℃), has uniform crystal grain size, high density and high mechanical property of the ceramic obtained by sintering, and meets the requirements of the alumina ceramic of semiconductor equipment.

In some embodiments, the conditions for atmospheric degreasing sintering are: heating to 600 ℃ at the speed of 0.2-1 ℃/min, preserving heat for 6-10 h, then heating to 1200-1400 ℃ at the speed of 2-5 ℃/min, and preserving heat for 6-8 h.

In some embodiments, the degreasing sintering of the alumina ceramic body is performed using an atmospheric sintering furnace. So can once only accomplish degrease sintering work, avoid using the degrease stove alone to accomplish after the degrease, need the cooling and heat up again and carry out sintering operation. Meanwhile, relative to vacuum sintering, the method can save the setting of degreasing equipment, shorten the sintering time and improve the production efficiency.

And S18, grinding and polishing.

In some embodiments, the sintered alumina ceramic is subjected to surface grinding, drilling, grooving and other fine machining operations by using a CNC grinding machine.

In some embodiments, the alumina ceramic is polished by using a neutral polishing solution, and the surface roughness Ra of the alumina ceramic is controlled to be less than or equal to 0.1 μm through grinding and polishing.

Another embodiment of the present invention provides an alumina ceramic prepared by the above preparation method. The alumina ceramic has high density and good mechanical property, and can meet the requirements of semiconductor equipment on ceramic materials.

In some embodiments, the surface roughness Ra of the alumina ceramic is 0.1 μm or less.

The density of the alumina ceramic prepared by the method reaches 3.9g/cm³And above, compressive strength is more than 2600Mpa, volume resistivity is more than 10¹⁴Omega cm, a Hardness (HRA) of 88, a flexural strength of 350MPa to 360MPa, and a thermal expansion coefficient of 7.5X 10^-6/℃～8.5×10^-6The temperature per degree centigrade meets the use requirement of the semiconductor equipment for the alumina precision ceramics.

The following are specific examples.

Example 1

Raw materials: high-purity alumina powder: the purity of the alumina is more than 99.99 percent, and the particle size D50: 0.4 μm, BET: 13m²/g。

1) 2000g of grinding medium pure water is weighed, 20g of polyvinyl alcohol dispersing agent is weighed, and the dispersing agent is added into the pure water, stirred and dispersed uniformly to prepare premixed liquid.

2) Adding 2000g of high-purity alumina powder into the premixed liquid, stirring and dispersing into slurry, and then ball-milling for 5 hours by a high-speed sand mill to prepare alumina slurry with narrow particle size distribution and small particle size, wherein the D90 is less than 0.8 mu m.

3) And drying the alumina slurry in a spray dryer at the air inlet temperature of 280 ℃, the air outlet temperature of 120 ℃ and the rotation speed of an atomizing disc of 10000rpm to prepare the spherical alumina ultrafine powder.

4) Weighing 250g of polyacrylic resin, melting in an oil bath pan at 190 ℃, cooling the system to 120 ℃ after polyacrylic resin particles are completely melted to be in a liquid state, and adding 125g of stearic acid to melt the polyacrylic resin particles; the temperature of the system was again lowered to 80 ℃ and 50g of paraffin wax was added to melt it. After the whole organic matter is melted, 2000g of spherical alumina ultrafine powder prepared in the step 3 is slowly added into the system under the starting of a stirrer, 75g of salicylic acid benzene ester serving as an ultraviolet light absorber is added into the system after the alumina ultrafine powder is dispersed into a slurry state in the system, and the stirring is continuously carried out for 3 hours. The whole photocuring alumina slurry system is uniformly distributed, and finally the slurry of the system is transferred to a 3D printer charging bucket after being subjected to vacuum treatment for 15 min.

5) And finishing the forming work of the alumina ceramic by using a photocuring ceramic 3D printer under the ultraviolet irradiation condition according to the requirements of the drawing.

6) Placing the formed alumina ceramic blank in a normal-pressure degreasing sintering furnace, heating the furnace temperature to 600 ℃ according to the heating rate of 0.5 ℃/min, and preserving the temperature for 6 hours to finish degreasing operation of the alumina ceramic, so as to completely remove organic grease; the temperature of the alumina ceramic is continuously increased to 1400 ℃ according to the temperature rising rate of 2.5 ℃/min, and the temperature is kept at 1400 ℃ for 6 h. After high-temperature sintering, the alumina is naturally cooled to below 200 ℃ along with the sintering furnace and then discharged out of the furnace, and the sintering is finished, so that the alumina ceramic sintered body is prepared.

7) And the aluminum oxide ceramic sintered body is ground and finely processed by CNC and then polished by neutral polishing solution, and the surface roughness Ra of the aluminum oxide ceramic sintered body is less than 0.1 mu m.

Example 2

Raw materials: high-purity alumina powder: the purity of the alumina is more than 99.99 percent, and the particle size D50: 0.3 μm, BET: 15m²/g。

1) Weighing 2000g of grinding medium pure water, weighing 20g of polyvinyl alcohol dispersant, adding the dispersant into the pure water, stirring and dispersing uniformly to prepare a premixed solution.

2) Adding 2000g of high-purity alumina powder into the premixed liquid, stirring and dispersing into slurry, and then ball-milling for 4 hours by a high-speed sand mill to prepare alumina slurry with narrow particle size distribution and small particle size, wherein D90 is less than 0.8 mu m.

3) And drying the alumina slurry in a spray dryer at the drying air inlet temperature of 280 ℃, the air outlet temperature of 120 ℃ and the rotation speed of an atomizing disc of 10000rpm to prepare the spherical alumina ultrafine powder.

4) Weighing 200g of polyacrylic resin, melting in an oil bath pan at 190 ℃, cooling the system to 120 ℃ after polyacrylic resin particles are completely melted into liquid, and adding 150g of stearic acid to melt the polyacrylic resin particles; the temperature of the system was again lowered to 80 ℃ and 75g of paraffin wax was added to melt it. After the whole organic matter is melted, 2000g of the spherical alumina powder prepared in the step 3 is slowly added into the system under the starting of a stirrer, 75g of salicylic acid phenyl ester serving as an ultraviolet absorber is added into the system after the alumina powder is dispersed into a slurry state in the system, and the stirring is continuously carried out for 4 hours. The whole photocuring alumina slurry system is uniformly distributed, and finally the slurry of the system is transferred to a 3D printer charging bucket after being subjected to vacuum treatment for 15 min.

5) And finishing the alumina ceramic molding work by using a photocuring ceramic 3D printer under the ultraviolet irradiation condition according to the drawing requirements.

6) Placing the formed alumina ceramic blank in a normal-pressure degreasing sintering furnace, heating the furnace temperature to 600 ℃ according to the heating rate of 0.5 ℃/min, and preserving the temperature for 6 hours to finish degreasing operation of the alumina ceramic, so as to completely remove organic grease; the temperature of the alumina ceramic is continuously increased to 1350 ℃ according to the temperature increasing rate of 2.0 ℃/min, and the temperature is kept at 1350 ℃ for 8 h. After high-temperature sintering, the alumina is naturally cooled to below 200 ℃ along with the sintering furnace and then discharged out of the furnace, and the sintering is finished, so that the alumina ceramic sintered body is prepared.

Example 3

Raw materials: high-purity alumina powder: the purity of the alumina is more than 99.99 percent, and the particle size D50: 0.3 μm, BET: 18m²/g。

4) Weighing 225g of polyacrylic resin, melting in an oil bath pan at 190 ℃, cooling the system to 120 ℃ after polyacrylic resin particles are completely melted to be liquid, and adding 100g of stearic acid to melt the polyacrylic resin particles; the temperature of the system is reduced to 80 ℃ again, and 100g of paraffin is added to melt the system. After the whole organic matter is melted, 2000g of spherical alumina powder prepared in the step 3 is slowly added into the system under the condition that a stirrer is started, 75g of ultraviolet absorbent phenyl salicylate is added into the system after the alumina powder is dispersed into a slurry state in the system, and the stirring is continuously carried out for 3 hours. The whole photocuring alumina slurry system is uniformly distributed, and finally the slurry of the system is transferred to a 3D printer charging bucket after being subjected to vacuum treatment for 15 min.

6) Placing the formed alumina ceramic blank in a normal-pressure degreasing sintering furnace, heating the furnace temperature to 600 ℃ according to the heating rate of 0.5 ℃/min, and preserving the temperature for 6 hours to finish the degreasing operation of the alumina ceramic, so as to completely remove organic grease; the temperature of the alumina ceramic is continuously increased to 1300 ℃ according to the temperature rising rate of 2.0 ℃/min, and the temperature is kept at 1300 ℃ for 7 h. After high-temperature sintering, the alumina is naturally cooled to below 200 ℃ along with the sintering furnace and then discharged out of the furnace, and the sintering is finished, so that the alumina ceramic sintered body is prepared.

7) And grinding and finely processing the aluminum oxide ceramic sintered body by CNC, and then polishing by using neutral polishing solution, wherein the surface roughness Ra of the aluminum oxide ceramic sintered body is less than 0.1 mu m.

Comparative example 1

Raw materials: high-purity alumina powder: the purity of the alumina is more than 99.99 percent, and the particle size D50: 2.5 μm, BET: 8m²/g。

2) Adding 2000g of high-purity alumina powder into the premixed solution, stirring and dispersing into slurry, and ball-milling for 5 hours by a high-speed sand mill to obtain alumina slurry, wherein D90 is 5 microns.

3) And drying the alumina slurry in a spray dryer at the drying air inlet temperature of 280 ℃, the air outlet temperature of 120 ℃ and the rotation speed of an atomizing disc of 10000rpm to prepare the spherical alumina powder.

4) Weighing 250g of polyacrylic resin, melting in an oil bath pan at 190 ℃, cooling the system to 120 ℃ after polyacrylic resin particles are completely melted to be in a liquid state, and adding 125g of stearic acid to melt the polyacrylic resin particles; the temperature of the system was again lowered to 80 ℃ and 50g of paraffin wax was added to melt it. After the whole organic matter is melted, 2000g of the spherical alumina powder prepared in the step 3 is slowly added into the system under the starting of a stirrer, 75g of salicylic acid phenyl ester serving as an ultraviolet absorber is added into the system after the alumina powder is dispersed into a slurry state in the system, and the stirring is continuously carried out for 3 hours. The whole photocuring alumina slurry system is uniformly distributed, and finally the slurry of the system is transferred to a 3D printer charging bucket after being subjected to vacuum treatment for 15 min.

6) Placing the formed alumina ceramic blank in a normal-pressure degreasing sintering furnace, heating the furnace temperature to 600 ℃ according to the heating rate of 0.5 ℃/min, and preserving the temperature for 6 hours to finish the degreasing operation of the alumina ceramic, so as to completely remove organic grease; the temperature of the alumina ceramic is continuously increased to 1400 ℃ according to the temperature rising rate of 2.5 ℃/min, and the temperature is kept at 1400 ℃ for 6 h. After high-temperature sintering, the alumina is naturally cooled to below 200 ℃ along with the sintering furnace and then is discharged out of the furnace, and the firing is finished.

Comparative example 2

3) And drying the alumina slurry in a spray dryer at the drying temperature of 280 ℃ and the rotation speed of an atomizing disc of 10000rpm to prepare the spherical alumina powder.

4) Weighing 250g of polyacrylic resin, melting in an oil bath pan at 190 ℃, cooling the system to 120 ℃ after polyacrylic resin particles are completely melted to be in a liquid state, and adding 125g of stearic acid to melt the polyacrylic resin particles; the temperature of the system is reduced to 80 ℃ again, and 50g of paraffin is added to melt the system. After the whole organic matter is melted, 2000g of the spherical alumina powder prepared in the step 3 is slowly added into the system under the starting of a stirrer, 75g of salicylic acid phenyl ester serving as an ultraviolet absorber is added into the system after the alumina powder is dispersed into a slurry state in the system, and the stirring is continuously carried out for 3 hours. The whole photocuring alumina slurry system is uniformly distributed, and finally the slurry of the system is transferred to a 3D printer charging bucket after being subjected to vacuum treatment for 15 min.

6) Placing the formed alumina ceramic blank in a normal-pressure degreasing sintering furnace, heating the furnace temperature to 600 ℃ according to the heating rate of 0.5 ℃/min, and preserving the temperature for 6 hours to finish the degreasing operation of the alumina ceramic, so as to completely remove organic grease; the temperature of the alumina ceramic is continuously increased to 1700 ℃ according to the temperature rising rate of 2.5 ℃/min, and the temperature is kept at 1700 ℃ for 6 h. After high-temperature sintering, the alumina is naturally cooled to below 200 ℃ along with the sintering furnace and then is discharged out of the furnace, and the firing is finished.

Comparative example 3

Raw materials: purity of alumina 95%, particle size D50: 0.3 μm, BET: 15m²/g。

1) Weighing 2000g of grinding medium pure water, weighing 20g of polyvinyl alcohol dispersant, adding the dispersant solution into the pure water, stirring and dispersing uniformly to prepare a premixed solution.

2) Adding 2000g of alumina powder into the premixed solution, stirring and dispersing into slurry, and ball-milling the alumina slurry for 4 hours by a high-speed sand mill to prepare the alumina slurry with narrow particle size distribution and small particle size, wherein D90 is less than 0.8 mu m.

3) And drying the slurry in a spray dryer at the drying temperature of 280 ℃ and the rotation speed of an atomizing disc of 10000rpm to prepare the spherical alumina ultrafine powder.

4) Weighing 200g of polyacrylic resin, melting in an oil bath pan at 190 ℃, cooling the system to 120 ℃ after polyacrylic resin particles are completely melted into liquid, and adding 150g of stearic acid to melt the polyacrylic resin particles; the temperature of the system was again lowered to 80 ℃ and 75g of paraffin wax was added to melt it. And (3) melting the whole organic matters, slowly adding 2000g of the spherical alumina ultrafine powder prepared in the step (3) into the system under the starting of a stirrer, dispersing the alumina ultrafine powder into the system into a slurry state, then adding 75g of salicylic acid benzene ester serving as an ultraviolet light absorber into the system, and continuously stirring for 4 hours. The whole photocuring alumina slurry system is uniformly distributed, and finally the slurry of the system is transferred to a 3D printer charging bucket after being subjected to vacuum treatment for 15 min.

6) Placing the formed alumina ceramic blank in a normal-pressure degreasing sintering furnace, heating the furnace temperature to 600 ℃ according to the heating rate of 0.5 ℃/min, and preserving the temperature for 6 hours to finish degreasing operation of the alumina ceramic, so as to completely remove organic grease; the temperature of the alumina ceramic is continuously increased to 1350 ℃ according to the temperature rising rate of 2.0 ℃/min, and the temperature is preserved for 8h at 1350 ℃. After high-temperature sintering, the alumina is naturally cooled to below 200 ℃ along with the sintering furnace and then is discharged out of the furnace, and the firing is finished.

The alumina ceramics prepared in examples 1 to 3 and comparative examples 1 to 3 were subjected to performance tests, and the test results are shown in table 1 below.

The test standards of each performance test item are respectively as follows:

density: GB/T25995-2010;

compressive strength: GB/T4740-1999;

volume resistivity: GB/T31838.2-2019;

hardness (HRA): GB/T16534-2009;

breaking strength: GB/T3002-2004;

coefficient of thermal expansion: GB T16535-.

TABLE 1

As can be seen from table 2 above, in embodiments 1 to 3 of the present invention, high-purity alumina powder is used as a raw material, and is subjected to ball milling, spray drying, 3D printing and molding, and then low-temperature normal-pressure sintering, such that a high-density, fine-grain, high-strength, high-toughness, high-hardness, high-temperature-resistant, low-thermal expansion coefficient, and insulating precision alumina ceramic can be prepared. The alumina ceramic of the comparative example 1 has a lower density, is not fully sintered and compact, and does not meet the use requirement of the alumina precision ceramic of the semiconductor equipment, which shows that the performance index of the alumina raw material powder has an obvious effect on reducing the sintering temperature, when the particle size of the alumina raw material powder is too large or the particle size of the ground slurry is too large, the sintering activity of the powder is reduced, and compact sintering cannot be completed at a lower temperature, so that the density of the sintered ceramic is lower, and other performance indexes of the corresponding ceramic are also reduced. The comparative example 2 and the comparative example 1 adopt the same alumina powder and treatment process, when the sintering temperature is changed to 1700 ℃, the density of the alumina ceramic is improved, but the process has high requirement on the sintering temperature, the energy consumption and the equipment cost are increased, and the performance parameters of the fired alumina ceramic are different from the performance of the embodiment of the invention, particularly the compressive strength and the flexural strength are obviously poorer than the embodiment of the invention. Comparative example 3 and example 2 used alumina raw material powder of the same particle size, but the alumina purity was 95%, other processing techniques were the same, but from the analysis of performance parameters of the sintered alumina ceramic, it can be seen that the alumina raw material powder purity had a greater effect on the preparation of alumina ceramic for semiconductor devices, impurities contained in alumina were not dissolved in the alumina during the high temperature liquid phase reaction, which prevented the alumina crystal from fusing, increased the energy required for the reaction, and also resulted in a low density of the sintered product, and the corresponding other properties such as hardness, compressive strength and flexural strength were inferior in mechanical properties.

All possible combinations of the technical features of the above embodiments may not be described for the sake of brevity, but should be considered as within the scope of the present disclosure as long as there is no contradiction between the combinations of the technical features.

The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is specific and detailed, but not to be understood as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent should be subject to the appended claims.

Claims

1. The preparation method of the alumina ceramic is characterized by comprising the following steps:

preparing alumina powder into slurry to obtain alumina slurry with the particle size D90 less than or equal to 0.8 mu m; drying the alumina slurry to obtain alumina fine powder; the content of alumina in the alumina powder is more than or equal to 99 wt%;

3D printing and molding the alumina photocuring slurry to obtain an alumina ceramic blank; then directly degreasing and sintering the aluminum oxide ceramic blank under normal pressure to obtain aluminum oxide ceramic;

the conditions of the normal-pressure degreasing sintering are as follows: heating to 600 ℃ at the speed of (0.2-1) DEG C/min, preserving heat for 6-10 h, then heating to 1200-1400 ℃ at the speed of (2-5) DEG C/min, and preserving heat for 6-8 h;

in the alumina photocuring slurry, by weight, 80-85 parts of alumina fine powder, 5-10 parts of photosensitive resin, 1-10 parts of a first dispersing agent, 2-10 parts of a lubricant and 1-5 parts of an ultraviolet absorber are added;

the D50 of the alumina in the alumina powder is 0.3-0.6 μm, and the BET is 10m²/g～20m²/g；

The photosensitive resin is selected from at least one of polyacrylic resin, epoxy acrylic resin, polyurethane acrylic resin and polyester acrylic resin.

2. The method for producing an alumina ceramic according to claim 1,

the first dispersant is at least one selected from stearic acid, oleic acid and polyethylene glycol; and/or

The lubricant is selected from at least one of paraffin and glycerol; and/or

The ultraviolet light absorber is at least one of phenyl salicylate, 2, 4-dihydroxy benzophenone and resorcinol monobenzoate.

3. The method of claim 1, wherein the photosensitive resin is a polyacrylic resin, the first dispersant is stearic acid, the lubricant is paraffin, and the ultraviolet light absorber is phenyl salicylate.

4. The method for preparing alumina ceramic according to claim 1, wherein the step of preparing alumina powder into slurry comprises: mixing water, a second dispersing agent and the alumina powder, and then carrying out ball milling for 2-6 h, wherein the weight ratio of the alumina powder to the water is (4-7) to (3-6), the weight of the second dispersing agent is 1-3% of that of the alumina powder, and the second dispersing agent is an organic solvent.

5. The method of claim 4, wherein the second dispersant is at least one selected from the group consisting of polyvinyl alcohol, polyethylene glycol, and polystyrene.

6. The preparation method of the alumina ceramic according to claim 1, wherein the drying is performed by spray drying, and the inlet air temperature of the drying is 250-350 ℃, the outlet air temperature is 100-150 ℃, and the rotation speed is 9000-12000 rpm.

7. The method for preparing the alumina ceramic according to any one of claims 1 to 6, further comprising a step of grinding and polishing the alumina ceramic after the atmospheric degreasing and sintering, so as to control the surface roughness Ra of the alumina ceramic after grinding and polishing to be less than or equal to 0.1 μm.

8. An alumina ceramic, characterized by being prepared by the method for preparing an alumina ceramic according to any one of claims 1 to 7.