阅读说明：本技术 一种基于转移法的氧化铝陶瓷膜制备方法 (Alumina ceramic membrane preparation method based on transfer method ) 是由 鲁芷伶 于 2021-08-31 设计创作，主要内容包括：本发明属于涉及陶瓷膜技术领域,公开了一种基于转移法的氧化铝陶瓷膜制备方法,包括以下步骤：S1、制备氧化铝支撑体生胚；S2、制备预制膜；S3、转移与烧结,具体为将干燥的预制膜放置到用水微微湿润的氧化铝支撑体生胚表面,进一步干燥,最后高温烧结,在高温烧结的过程中,预制膜中的水、有机物会蒸发气化,膜中有机物和水分的丢失会增大膜的通量。本发明与传统在支撑体表面喷涂制膜的方式相比,这个方法的优势在于,预制膜的是脱离支撑体独立制备,可以单独精确地调控其性质,如厚度、孔径和孔隙率等。另一方面,转移法可以避免其他传统方法在成膜过程中的颗粒渗透,这是造成膜层过滤阻力过大、通量损失的主要原因之一。(The invention belongs to the technical field of ceramic membranes, and discloses a method for preparing an alumina ceramic membrane based on a transfer method, which comprises the following steps: s1, preparing an alumina support body green blank; s2, preparing a prefabricated film; s3, transferring and sintering, specifically, placing the dried prefabricated membrane on the surface of the alumina support green body slightly wetted by water, further drying, and finally sintering at high temperature, wherein in the process of sintering at high temperature, water and organic matters in the prefabricated membrane can be evaporated and gasified, and the flux of the membrane can be increased due to the loss of the organic matters and the water in the membrane. Compared with the traditional method for preparing the membrane by spraying on the surface of the support, the method has the advantages that the prefabricated membrane is independently prepared from the support, and the properties such as thickness, pore diameter, porosity and the like of the prefabricated membrane can be independently and accurately regulated. On the other hand, the transfer method can avoid the penetration of particles in the film forming process of other traditional methods, which is one of the main reasons of overlarge membrane filtration resistance and flux loss.)

1. A preparation method of an alumina ceramic membrane based on a transfer method is characterized by comprising the following steps:

s1, preparing an alumina support body green blank;

s1.1, selecting spherical alumina powder with the diameter within the range of 35-50 um;

s1.2, stirring and mixing 2-14 wt% of silica sol and spherical alumina powder in proportion, and adjusting the pH to be neutral by using dilute hydrochloric acid to prepare slurry, wherein the average particle size of the silica sol is far smaller than the diameter of the spherical alumina powder;

s1.3, drying the slurry in the S1.2 in an oven at 60 ℃ to constant weight;

s1.4, granulating the dried mixture by using an ethanol solution of 5 wt% PVB as an adhesive, and then carrying out dry pressing forming to form a wafer-shaped alumina support body green body;

s2, preparing a prefabricated film;

s3, transferring and sintering;

s3.1, wetting the surface of the alumina support body green blank by adopting trace water, and immediately placing the prefabricated film on the surface of the alumina support body green blank;

s3.2, drying the green embryo treated by the S3.1 at room temperature for 3 hours;

and S3.3, transferring the ceramic membrane to an oven for drying, heating, and cooling to room temperature along with the oven to obtain the alumina ceramic membrane.

2. The method of claim 1, wherein in step S1.1, the spherical alumina powder is sequentially passed through a standard 300-mesh sieve and a standard 400-mesh sieve, and the powder is collected on a 400-mesh sieve.

3. A method for preparing an alumina ceramic membrane based on the transfer method according to claim 1, wherein the step S1.4 is performed by dry press forming at 35 MPa.

4. The method according to claim 1, wherein the diameter of the alumina support green body in step S1.4 is 30mm and the thickness is 3 mm.

5. The method for preparing an alumina ceramic membrane according to claim 1, wherein the step S2 specifically comprises:

s2.1, mixing and ball-milling 100g of alumina powder with the particle diameter of 0.9-1.1 um, 100g of deionized water and an industrial dispersant for 1 hour to form uniform alumina suspension;

s2.2, mixing a PVA solution with a PVP solution to serve as an adhesive, adding glycerol serving as a plasticizer into the alumina suspension to prepare slurry;

s2.3, violently stirring the slurry in the S2.2 for 30 minutes, and then degassing in vacuum for 30 minutes;

s2.4, placing the slurry processed in the S2.3 on a platform, leveling by a scraper, and drying under a proper condition to obtain a prefabricated film;

s2.5, cutting the prefabricated film into small round blocks with the diameter of 30mm, and removing dust and grease on the surface for later use.

6. The method according to claim 5, wherein the mass ratio of PVA, PVP and glycerol in step S2.2 is constant at 2: 1: 2.

7. the method for preparing an alumina ceramic membrane based on the transfer method according to claim 5, wherein the height of the scraper in step S2.4 is controlled to be 100-300 μm, the feeding speed is 20mm/S, and the thickness of the prefabricated membrane is 10 μm.

8. The method for preparing an alumina ceramic membrane based on the transfer method according to claim 1, wherein the temperature of the oven in step S3.3 is 60 ℃ and the drying time is 6 hours.

9. The method according to claim 1, wherein the step S3.3 of heating and raising the temperature comprises heating to 600 ℃ at a rate of 2 ℃/min and holding for 1 hour, and then raising the temperature to 1300 ℃ at a maximum temperature of 10 ℃/min and holding for 2 hours.

Technical Field

The invention belongs to the technical field of ceramic membranes, and particularly relates to a preparation method of an alumina ceramic membrane based on a transfer method.

Background

The world is at the edge of a serious environmental crisis. Environmental problems caused by rapid industrialization are one of the important threats facing mankind in this century, and these problems include: water, soil and air pollution, global warming, over-population, exhaustion of natural resources, and the like. Water is an important resource indispensable to most industrial processes, and therefore the generation of wastewater is inevitable in all industries. Industrial and municipal sewage discharge has increased at the same rate with the rapid advance of economic growth, and there is increasing evidence of water quality deterioration due to industrial and domestic water pollution in many developing countries.

The membrane separation technology is an emerging technology capable of separating pollutants to relieve environmental pressure, has the advantages of low energy consumption, easiness in scale enlargement, high degree of mixing with other processes, continuous high strength, automatic operation and the like, and is called as a global technology.

Compared with polymer membranes, ceramic membranes have outstanding application prospects due to excellent mechanical properties, stability, easiness in cleaning and longer membrane life. The traditional ceramic membrane is designed into a multilayer gradient pore structure, the structure is transited from a bottom macroporous support body to a middle layer and then to a top separation layer, and the pore diameter is gradually reduced. The traditional ceramic membrane preparation method has the problems that membrane particles permeate into the support body, and the raw materials and the high preparation cost caused by multiple high-temperature treatments are high.

At present, ceramic membranes are used in very limited quantities on an industrial scale, mainly because of their high production costs, and because of the traditional production techniques, ceramic membranes have a multilayer (3 layers and above) structure, often achieved by multiple sintering. The approach for reducing the preparation cost of the ceramic membrane mainly lies in reducing the cost of raw materials and the high-temperature sintering cost, the raw materials determine the performance of the ceramic membrane to a great extent, and the reduction of the sintering times in the preparation process is undoubtedly the best choice. However, it is difficult to realize the one-step preparation of the support and the film layer. On one hand, the support body green body is required to have reasonable flux and strength, and simultaneously, the shrinkage rate is required to be matched with the prefabricated film, and most importantly, the prefabricated film and the support body green body can be tightly bonded.

Disclosure of Invention

Aiming at the problems in the prior art, the invention provides the preparation method of the alumina ceramic membrane based on the transfer method, the ceramic membrane has two layers, and can be finished by one-time high-temperature sintering, thereby simplifying the preparation process, reducing the process cost, increasing the flux compared with the multilayer alumina ceramic membrane, further enlarging the industrial application scale of the ceramic membrane and leading the ceramic membrane to become a substitute product of a polymer membrane.

The technical scheme comprises the following steps:

s1, preparing an alumina support body green blank;

s1.1, selecting spherical alumina powder with the diameter within the range of 35-50 um;

s1.2, stirring and mixing 2-14 wt% of silica sol and spherical alumina powder in proportion, and adjusting the pH to be neutral by using dilute hydrochloric acid to prepare slurry, wherein the average particle size of the silica sol is far smaller than the diameter of the spherical alumina powder;

s1.3, drying the slurry in the S1.2 in an oven at 60 ℃ to constant weight;

s1.4, granulating the dried mixture by using an ethanol solution of 5 wt% PVB as an adhesive, and then carrying out dry pressing forming to form a wafer-shaped alumina support body green body;

s2, preparing a prefabricated film;

s3, transferring and sintering;

s3.1, wetting the surface of the alumina support body green blank by adopting trace water, and immediately placing the prefabricated film on the surface of the alumina support body green blank;

s3.2, drying the green embryo treated by the S3.1 at room temperature for 3 hours;

and S3.3, transferring the ceramic membrane to an oven for drying, heating, and cooling to room temperature along with the oven to obtain the alumina ceramic membrane.

Further, in step S1.1, the spherical alumina powder sequentially passes through a standard sieve of 300 meshes and a standard sieve of 400 meshes, and powder on the standard sieve of 400 meshes is taken.

Further, in step S1.4, dry-pressing is carried out at 35 MPa.

Further, the alumina support in step S1.4 has a diameter of 30mm and a thickness of 3 mm.

Further, step S2 specifically includes:

s2.1, mixing and ball-milling 100g of alumina powder with the particle diameter of 0.9-1.1 um, 100g of deionized water and an industrial dispersant for 1 hour to form uniform alumina suspension;

s2.2, mixing a PVA solution with a PVP solution to serve as an adhesive, adding glycerol serving as a plasticizer into the alumina suspension to prepare slurry;

s2.3, violently stirring the slurry in the S2.2 for 30 minutes, and then degassing in vacuum for 30 minutes;

s2.4, placing the slurry processed in the S2.3 on a platform, leveling by a scraper, and drying under a proper condition to obtain a prefabricated film;

s2.5, cutting the prefabricated film into small round blocks with the diameter of 30mm, and removing dust and grease on the surface for later use.

Further, in step S2.2, the mass ratio of PVA, PVP and glycerol is constant at 2: 1: 2.

further, in step S2.4, the height of the scraper is controlled to be 100-300 μm, the feeding speed is 20mm/S, and the thickness of the prefabricated film is 10 μm.

Further, the temperature of the oven in step S3.3 is 60 ℃, and the drying time is 6 hours.

Further, the heating and temperature raising treatment in step S3.3 comprises heating to 600 ℃ at a speed of 2 ℃/min, maintaining the temperature for 1h, then raising to the maximum temperature of 1300 ℃ at a temperature of 10 ℃/min, and maintaining the temperature for 2 h.

The invention has the beneficial effects that:

(1) in the preparation of the alumina support body green body, the diameter of the spherical alumina powder and the average grain diameter of the silica sol are far smaller than the diameter of the spherical alumina powder, so that the use of a pore-forming agent is avoided, and the defects of cracks, bulges and the like of a film caused by gasification of the pore-forming agent during high-temperature sintering can be avoided; the diameter of the spherical alumina powder is limited, and the bending factor of the pore channel of the green body of the support body can be reduced due to the regular shape and the low specific surface area, so that the flux of the green body of the support body can be obviously improved; the silica sol is a sintering aid, so that the mechanical strength of the alumina support body green body can be increased by realizing co-sintering, and the high-temperature sintering temperature can be reduced; the dried prefabricated membrane is placed on the support body and sintered, so that the particle permeation phenomenon is blocked, an important factor of losing the permeability is removed, the high flux advantage of the ceramic membrane is fully exerted, and in addition, the ceramic membrane is obtained through one-time sintering, so that the production cost can be reduced, and the preparation period is shortened.

(2) According to the invention, through adding the organic additive comprising the adhesive and glycerol into the ingredients of the prefabricated membrane, wherein the adhesive is formed by mixing a PVA solution and a PVP solution, when the dry prefabricated membrane is in contact with the wet surface of the alumina support body green body, the adhesive is softened when in contact with water, the prefabricated membrane can be well attached to the alumina support body green body, the occurrence of a gas layer is prevented, and meanwhile, the permeation of membrane particles to the alumina support body green body is restrained by the existence of the adhesive; in addition, the shrinkage rate of the prefabricated membrane layer can be accurately adjusted by adjusting the content of the organic additive, so that the shrinkage rates of different layers of the alumina support body green blank are matched, and the sintering defects that the membrane surface has tensile stress or compression stress to cause cracks and the like due to overlarge difference of shrinkage rates are avoided, thereby influencing the quality of the membrane and prolonging the service life of the membrane.

(3) According to the invention, through the heating and temperature-raising treatment process, water and organic matters in the prefabricated membrane can be evaporated and gasified, and the flux of the prefabricated membrane can be increased due to the loss of the organic matters and the water in the prefabricated membrane.

Detailed Description

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

The invention provides an alumina ceramic membrane preparation method based on a transfer method, which comprises the following steps:

s1, preparing an alumina support body green blank;

s1.1, selecting spherical alumina powder with the diameter within the range of 35-50 um;

s1.2, stirring and mixing 2-14 wt% of silica sol and spherical alumina powder in proportion, and adjusting the pH to be neutral by using dilute hydrochloric acid to prepare slurry, wherein the average particle size of the silica sol is far smaller than the diameter of the spherical alumina powder, and the average diameter of the silica sol is preferably 23 nm;

s1.3, drying the slurry in the S1.2 in an oven at 60 ℃ to constant weight;

s1.4, granulating the dried mixture by using an ethanol solution of 5 wt% PVB as an adhesive, and then carrying out dry pressing forming to form a wafer-shaped alumina support body green body;

s2, preparing a prefabricated film;

s3, transferring and sintering;

s3.1, wetting the surface of the alumina support body green blank by adopting trace water, and immediately placing the prefabricated film on the surface of the alumina support body green blank;

s3.2, drying the green embryo treated by the S3.1 at room temperature for 3 hours;

and S3.3, transferring the ceramic membrane to an oven for drying, heating, and cooling to room temperature along with the oven to obtain the alumina ceramic membrane.

In the embodiment, in the preparation of the alumina support body green body, the diameter of the spherical alumina powder and the average particle size of the silica sol are far smaller than the diameter of the spherical alumina powder, so that the use of a pore-forming agent is avoided, and the defects of cracks, bulges and the like of a film caused by gasification of the pore-forming agent during high-temperature sintering can be avoided; the diameter of the spherical alumina powder is limited, and the bending factor of the pore channel of the green body of the support body can be reduced due to the regular shape and the low specific surface area, so that the flux of the green body of the support body can be obviously improved; the silica sol is a sintering aid, so that the mechanical strength of the alumina support body green body can be increased by realizing co-sintering, the high-temperature sintering temperature can be reduced, and the particle size of the silica sol is limited to mainly match the diameter of spherical alumina powder of the alumina support body green body, so that the silica sol is ensured to be fully contacted with the alumina powder. The silica sol is used as a sintering aid reagent to realize co-sintering, and the fusion degree of the silica sol and alumina powder is increased after high-temperature sintering, so that the strength of the support body is improved; the content is limited to the range of 2 wt% -14 wt%, because the content of silica sol is in linear relation with the porosity and is in negative relation, and the porosity of the support body is influenced and the flux is reduced due to the over-high content of silica sol; the ceramic membrane is obtained by one-time sintering, so that the production cost can be reduced and the preparation period can be shortened.

In this embodiment, preferably, in step S1.1, the spherical alumina powder passes through a standard sieve of 300 meshes and a standard sieve of 400 meshes in sequence, and a powder material on the 400 meshes is taken to obtain the spherical alumina powder with the diameter in the range of 35 to 50 um.

In this embodiment, the alumina support green sheet is preferably dry-pressed at 35MPa in step S1.4, and has a diameter of 30mm and a thickness of 3 mm.

In this embodiment, preferably, step S2 specifically includes:

s2.1, mixing and ball-milling 100g of alumina powder with the particle diameter of 0.9-1.1 um, 100g of deionized water and an industrial dispersant (Nopco-5040) for 1 hour to form uniform alumina suspension;

s2.2, mixing the PVA solution with the PVP solution to serve as a binding agent, adding glycerol to the alumina suspension to serve as a plasticizer to prepare slurry, wherein the mass ratio of PVA, PVP and glycerol is constant and is 2: 1: 2, ensuring that the solid content in the slurry is 20 wt%;

s2.3, violently stirring the slurry in the S2.2 for 30 minutes, and then degassing in vacuum for 30 minutes;

s2.4, placing the slurry processed in the step S2.3 on a platform, leveling the slurry by a scraper, and drying the slurry under a proper condition to obtain a prefabricated film, wherein the height of the scraper is controlled to be 100-300 mu m, the feeding speed is 20mm/S, and the thickness of the prefabricated film is 10 mu m;

s2.5, cutting the prefabricated film into small round blocks with the diameter of 30mm, and removing dust and grease on the surface for later use.

In the embodiment, by adding the organic additive comprising the adhesive and glycerol into the ingredients of the prefabricated membrane, wherein the adhesive is formed by mixing the PVA solution and the PVP solution, when the dried prefabricated membrane is in contact with the wet surface of the alumina support green body, the adhesive is softened when in contact with water, so that the prefabricated membrane can be well attached to the alumina support green body, the occurrence of a gas layer is prevented, and meanwhile, the permeation of membrane particles to the alumina support green body is restrained by the existence of the adhesive; in addition, the shrinkage rate of the prefabricated membrane layer can be accurately adjusted by adjusting the content of the organic additive, so that the shrinkage rates of different layers of the alumina support body green blank are matched, and the sintering defects that the membrane surface has tensile stress or compression stress to cause cracks and the like due to overlarge difference of shrinkage rates are avoided, thereby influencing the quality of the membrane and prolonging the service life of the membrane.

In this embodiment, it is preferable that the temperature of the oven in step S3.3 is 60 ℃ and the drying time is 6 hours.

In this embodiment, preferably, the heating and temperature raising process in step S3.3 includes heating to 600 ℃ at a speed of 2 ℃/min, maintaining the temperature for 1h, then heating to 1300 ℃ at a temperature of 10 ℃/min, and maintaining the temperature for 2h, and through the heating and temperature raising process, water and organic matters in the prefabricated membrane can be evaporated and gasified, and the flux of the prefabricated membrane can be increased due to the loss of the organic matters and water in the prefabricated membrane.

The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and combinations are possible for those skilled in the art. The present invention can be applied to various parts of semiconductor equipment, which require corrosion resistance, but is not limited to semiconductor equipment. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.