Alumina ceramic membrane sintering aid, and preparation method and application thereof

Abstract

The application discloses an alumina ceramic membrane sintering aid and a preparation method and application thereof, relates to the technical field of ceramic membranes, and the alumina ceramic membrane sintering aid is composed of nano silicon oxide and foamed powder, wherein the foamed powder comprises 20 parts of alumina powder, 50-80 parts of potassium feldspar, 5-20 parts of sodium feldspar, 0.1-1 part of sodium carboxymethyl cellulose, 0.1-1 part of sodium tripolyphosphate, 0.5-3 parts of sodium hexametaphosphate, 0.3-1 part of 1000-mesh manganese dioxide, 0.1-0.6 part of 1000-mesh silicon carbide and 100 parts of water. The alumina ceramic membrane sintering aid is controllable in particle size, and the temperature can be controlled when the alumina ceramic membrane sintering aid is applied to the preparation process of an alumina ceramic membrane support. In the preparation process of the alumina ceramic membrane support, the nano silicon dioxide in the sintering aid can adjust the viscosity of high-temperature liquid, accelerate the reaction between the sintering aid and the alumina powder, has a larger bridging effect, and the porous liquid at high temperature can guarantee the strength of the alumina ceramic membrane support and increase the porosity.

Description

Technical Field

[0001] This invention relates to the field of ceramic membrane technology, and in particular to an alumina ceramic membrane sintering aid, its preparation method, and its application. Background Technology

[0002] Ceramics are a type of material formed from various inorganic powders through powder preparation, molding, sintering, and processing. Ceramics are divided into traditional ceramics and special ceramics. Alumina ceramics have the largest market share in the special ceramics market due to their low raw material prices, good resistance to acid and alkali corrosion, and good mechanical properties. Alumina ceramic membranes, which combine alumina ceramics with membrane science, also occupy an important position in the membrane market.

[0003] Currently, in the market, alumina ceramic membranes still lag significantly behind traditional organic membranes. Except for use in special environments such as acidic, alkaline, and high-temperature conditions, organic membranes remain the dominant technology in other applications, such as domestic and municipal wastewater treatment. The reason for this is that, for the same flow rate, ceramic membranes are far more expensive than organic membranes. The high cost of ceramic membranes stems from the fact that maintaining a certain flow rate requires maintaining a certain porosity, but higher porosity leads to lower strength, making it difficult to achieve a balance. To achieve the required strength, ceramic membranes often have lower porosity, indirectly resulting in no significant advantage in the square footage required for the same water production compared to organic membranes. In the ceramic membrane manufacturing process, the key to determining the porosity and strength lies in the selection and use of sintering aids. Therefore, developing an alumina ceramic membrane sintering aid that can maintain both high porosity and minimal strength variation is of positive significance for ceramic membrane preparation. Summary of the Invention

[0004] In view of this, the purpose of this invention is to provide an alumina ceramic film sintering aid, its preparation method and application, so as to solve the problem that existing alumina ceramic film sintering aids cannot simultaneously ensure the porosity and strength of the ceramic film.

[0005] The present invention solves the above-mentioned technical problems through the following technical means:

[0006] In a first aspect, the present invention provides an alumina ceramic film sintering aid, wherein the alumina ceramic film sintering aid is composed of nano-silica and foaming powder, and the foaming powder comprises the following raw materials in parts by weight:

[0007] 20 parts alumina powder, 50-80 parts potassium feldspar, 5-20 parts sodium feldspar, 0.1-1 part sodium carboxymethyl cellulose, 0.1-1 part sodium tripolyphosphate, 0.5-3 parts sodium hexametaphosphate, 0.3-1 part 1000 mesh manganese dioxide, 0.1-0.6 parts 1000 mesh silicon carbide, and 100 parts water.

[0008] In conjunction with the first aspect, in some embodiments, the mass ratio of the nano-silica to the foamed powder is 0.3:1.

[0009] In conjunction with the first aspect, in some embodiments, the particle size D50 of the alumina ceramic film sintering aid is 0.5-3 μm, and the particle size distribution (D90-D10) / D50 ≤ 3.0.

[0010] In conjunction with the first aspect, in some embodiments, the particle size D50 of the alumina powder is 0.5-5 μm, and the particle size distribution (D90-D10) / D50 ≤ 3.0.

[0011] Secondly, the present invention provides a method for preparing an alumina ceramic film sintering aid, comprising the following steps:

[0012] 1) Preparation of foamed powder: Take alumina powder, potassium feldspar, sodium feldspar, sodium carboxymethyl cellulose, sodium tripolyphosphate, sodium hexametaphosphate, 1000 mesh manganese dioxide, 1000 mesh silicon carbide and water, put them into a wet ball mill for mixing and ball milling. After ball milling, the mixture is granulated and dried in a spray drying tower. The resulting powder is passed through a 60 mesh sieve to obtain foamed powder.

[0013] 2) Preparation of sol-gel mixture: Take an equal mass of 30% concentration of silica sol from the foamed powder, pour it into a high-speed stirring tank, and stir for 10-24 hours to obtain the sol-gel mixture;

[0014] 3) Preparation of alumina ceramic membrane sintering aid: The sol-gel mixture is dried at 120℃ for 10-24h, and then gradually fed into a Raymond mill for crushing. The resulting powder is passed through a 60-mesh sieve and then gradually fed into an air jet mill for classification. Powder with a particle size D50 of 0.5-3μm and a particle size distribution (D90-D10) / D50≤3.0 is collected, which is the alumina ceramic membrane sintering aid.

[0015] In conjunction with the second aspect, in some embodiments, the mixing and ball milling time is 10-48 hours, and the ball milling speed is 5-10 r / min.

[0016] Thirdly, the present invention provides an alumina ceramic film sintering aid as described in the first aspect or an alumina ceramic film sintering aid prepared by the preparation method described in the second aspect for use in alumina ceramic film supports and alumina film slurries.

[0017] The beneficial effects of this invention are:

[0018] The alumina ceramic membrane sintering aid of this invention has controllable particle size and can be applied to the temperature controllable process of preparing the alumina ceramic membrane support. In the preparation process of the alumina ceramic membrane support, the foamed powder in the sintering aid has the following properties: at a specific temperature, it sinterstens inorganic powder into a liquid with high viscosity, and at the same time, it forms porous powder in the liquid. Because the liquid viscosity is high, the formed pores are not easily blocked. Nano-silica can adjust the viscosity of the high-temperature liquid and accelerate the reaction between the sintering aid and the alumina powder, and has a large bridging effect. The porous liquid at high temperature can ensure that the flexural strength of the alumina ceramic membrane support reaches more than 50 MPa, and the porosity reaches more than 40%, indirectly providing a feasible solution for reducing the preparation cost of ceramic membranes. Attached Figure Description

[0019] Figure 1 The pore size distribution diagram is shown for the ceramic membrane support prepared using the alumina ceramic membrane sintering aid prepared in Example 1 and alumina powder with an average particle size of 5 μm.

[0020] Figure 2 The pore size distribution diagram is shown for the ceramic membrane support prepared using the alumina ceramic membrane sintering aid prepared in Example 2 and alumina powder with an average particle size of 3 μm.

[0021] Figure 3 The pore size distribution diagram is shown for the ceramic membrane support prepared using the alumina ceramic membrane sintering aid prepared in Example 3 and alumina powder with an average particle size of 1 μm.

[0022] Figure 4 Electron micrograph of a ceramic film support prepared using alumina ceramic film sintering aid prepared in Example 1 and alumina powder with an average particle size of 5 μm.

[0023] Figure 5 Electron micrograph of a ceramic film support prepared using alumina ceramic film sintering aid prepared in Example 2 and alumina powder with an average particle size of 3 μm.

[0024] Figure 6 Electron micrograph of a ceramic film support prepared using alumina ceramic film sintering aid prepared in Example 3 and alumina powder with an average particle size of 1 μm. Detailed Implementation

[0025] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0026] Unless otherwise specified in the following examples, the conditions are as per standard conditions or the manufacturer's recommendations. Raw materials, equipment, or instruments whose manufacturers are not specified are all commercially available products.

[0027] This invention proposes an alumina ceramic film sintering aid, which is composed of nano-silica and foaming powder. The foaming powder comprises the following raw materials in parts by weight:

[0028] 20 parts alumina powder, 50-80 parts potassium feldspar, 5-20 parts sodium feldspar, 0.1-1 part sodium carboxymethyl cellulose, 0.1-1 part sodium tripolyphosphate, 0.5-3 parts sodium hexametaphosphate, 0.3-1 part 1000 mesh manganese dioxide, 0.1-0.6 parts 1000 mesh silicon carbide, and 100 parts water.

[0029] Preferably, the mass ratio of nano-silica to foamed powder is 0.3:1.

[0030] Preferably, the particle size D50 of the alumina ceramic film sintering aid is 0.5-3μm, and the particle size distribution (D90-D10) / D50 ≤ 3.0.

[0031] Preferably, the particle size D50 of the alumina powder is 0.5-5μm, and the particle size distribution (D90-D10) / D50 ≤ 3.0.

[0032] The preparation method of the alumina ceramic film sintering aid is as follows:

[0033] 1) Preparation of foamed powder: Take alumina powder, potassium feldspar, sodium feldspar, sodium carboxymethyl cellulose, sodium tripolyphosphate, sodium hexametaphosphate, 1000 mesh manganese dioxide, 1000 mesh silicon carbide and water, put them into a wet ball mill for mixing and ball milling. After ball milling, the mixture is granulated and dried in a spray drying tower. The resulting powder is passed through a 60 mesh sieve to obtain foamed powder.

[0034] 2) Preparation of sol-gel mixture: Take an equal mass of 30% concentration of silica sol from the foamed powder, pour it into a high-speed stirring tank, and stir for 10-24 hours to obtain the sol-gel mixture;

[0035] 3) Preparation of alumina ceramic membrane sintering aid: The sol-gel mixture is dried at 120℃ for 10-24h, and then gradually fed into a Raymond mill for crushing. The resulting powder is passed through a 60-mesh sieve and then gradually fed into an air jet mill for classification. Powder with a particle size D50 of 0.5-3μm and a particle size distribution (D90-D10) / D50≤3.0 is collected, which is the alumina ceramic membrane sintering aid.

[0036] Preferably, the mixing and ball milling time is 10-48 hours, and the ball milling speed is 5-10 r / min.

[0037] The following examples 1-3 provide a detailed description of an alumina ceramic film sintering aid of the present invention, its preparation method, and its application.

[0038] Example 1

[0039] This embodiment provides a method for preparing an alumina ceramic film sintering aid, the steps of which are as follows:

[0040] 1) Preparation of foamed powder: Weigh 20g of alumina powder with a particle size D50 of 5μm and a particle size distribution (D90-D10) / D50≤3.0; weigh 80g of potassium feldspar, 20g of sodium feldspar, 1g of sodium carboxymethyl cellulose, 1g of sodium tripolyphosphate, 3g of sodium hexametaphosphate, 1g of 1000-mesh manganese dioxide, 0.6g of 1000-mesh silicon carbide, and 100g of water. Mix all the ingredients in a wet ball mill and ball mill them. The ball milling time is 48h and the ball milling speed is 10r / min. After ball milling, the powder is granulated and dried in a spray drying tower. All powders are passed through a 60-mesh sieve. The resulting powder is the foamed powder.

[0041] 2) Preparation of sol-gel mixture: Weigh out an equal mass of 30% concentration silica sol to the foaming powder, pour it all into a high-speed stirring tank, and stir for 24 hours to ensure that the foaming powder is evenly dispersed in the silica sol to obtain a sol-gel mixture.

[0042] 3) Preparation of alumina ceramic film sintering aid: The sol-gel mixture was poured into a 316L stainless steel basin and dried at 120℃ for 24 hours. Then, it was gradually fed into a Raymond mill for crushing. The resulting powder was passed through a 60-mesh sieve and then gradually fed into an air jet mill for classification. Powder with a particle size D50 of 3μm and a particle size distribution (D90-D10) / D50≤3.0 was collected. The resulting powder is a uniform mixture of nano-silica and foamed powder, which is the alumina ceramic film sintering aid.

[0043] Example 2

[0044] This embodiment provides a method for preparing an alumina ceramic film sintering aid, the steps of which are as follows:

[0045] 1) Preparation of foamed powder: 20g of alumina powder with a particle size D50 of 3μm and a particle size distribution (D90-D10) / D50≤3.0; 70g of potassium feldspar, 10g of sodium feldspar, 0.2g of sodium carboxymethyl cellulose, 0.5g of sodium tripolyphosphate, 0.9g of sodium hexametaphosphate, 0.9g of 1000-mesh manganese dioxide, 0.3g of 1000-mesh silicon carbide, and 100g of water were all mixed and ball-milled in a wet ball mill for 24 hours at a speed of 8r / min. After ball milling, the powder was granulated and dried in a spray drying tower. All powders were passed through a 60-mesh sieve. The resulting powder is the foamed powder.

[0046] 2) Weigh out an equal mass of 30% concentration silica sol from the foaming powder and pour it all into a high-speed mixing tank. Stir for 16 hours to ensure that the foaming powder is evenly dispersed in the silica sol to obtain a sol-gel mixture.

[0047] 3) Preparation of alumina ceramic membrane sintering aid: The sol-gel mixture was poured into a 316L stainless steel basin and dried at 120℃ for 18 hours. Then, it was gradually fed into a Raymond mill for crushing. The resulting powder was passed through a 60-mesh sieve and then gradually fed into an air jet mill for classification. Powder with a particle size D50 of 2μm and a particle size distribution (D90-D10) / D50≤3.0 was collected. The resulting powder is a uniform mixture of nano-silica and foamed powder, which is the alumina ceramic membrane sintering aid.

[0048] Example 3

[0049] This embodiment provides a method for preparing an alumina ceramic film sintering aid, the steps of which are as follows:

[0050] 1) Preparation of foamed powder: 20g of alumina powder with a particle size D50 of 0.5μm and a particle size distribution (D90-D10) / D50≤3.0; 50g of potassium feldspar, 5g of sodium feldspar, 0.1g of sodium carboxymethyl cellulose, 0.1g of sodium tripolyphosphate, 0.5g of sodium hexametaphosphate, 0.3g of 1000-mesh manganese dioxide, 0.1g of 1000-mesh silicon carbide, and 100g of water are all mixed and ball-milled in a wet ball mill for 10 hours at a speed of 5r / min. After ball milling, the powder is granulated and dried in a spray drying tower. All powders are passed through a 60-mesh sieve. The resulting powder is the foamed powder.

[0051] 2) Preparation of sol-gel mixture: Weigh out an equal mass of 30% concentration silica sol from the foaming powder and pour it all into a high-speed mixing tank. Stir for 10 hours to ensure that the foaming powder is evenly dispersed in the silica sol to obtain a sol-gel mixture.

[0052] 3) Preparation of alumina ceramic membrane sintering aid: The sol-gel mixture was poured into a 316L stainless steel basin and dried at 120℃ for 10 hours. Then, it was gradually fed into a Raymond mill for crushing. The resulting powder was passed through a 60-mesh sieve and then gradually fed into an air jet mill for classification. Powder with a particle size D50 of 0.5μm and a particle size distribution (D90-D10) / D50≤3.0 was collected. The resulting powder is a uniform mixture of nano-silica and foamed powder, which is the alumina ceramic membrane sintering aid.

[0053] The performance of the alumina ceramic film sintering aids obtained in Examples 1 to 3 was tested, as follows:

[0054] (1) 1000g of alumina powder with an average particle size of 5μm and 100g of the alumina ceramic membrane sintering aid prepared in Example 1 were all poured into a solid powder mixer. The alumina ceramic membrane support was prepared by kneading, mixing, aging, extrusion, drying, sintering, and cutting. The sintering temperature was 1300-1350℃. Using a PSDA-30 membrane material pore size analyzer, the pore size and distribution of the prepared alumina ceramic membrane support were tested at room temperature using the bubble pressure method. The wetting solution was isopropanol. The test results are as follows: Figure 1 As shown, the average pore size of the obtained alumina ceramic film support is 0.587 μm, and the porosity is 45.24%. The flexural strength of the alumina ceramic film support was tested using a HYK-DPK digital display electric flexural strength tester and found to be 60 MPa. The microstructure of the material was observed using scanning electron microscopy, and the results are as follows. Figure 4 As shown.

[0055] (2) 1000g of alumina powder with an average particle size of 3μm and 100g of the alumina ceramic membrane sintering aid prepared in Example 2 were poured into a solid powder mixer. The alumina ceramic membrane support was prepared by kneading, mixing, aging, extrusion, drying, sintering, and cutting. The sintering temperature was 1250-1300℃. Using a PSDA-30 membrane material pore size analyzer, the pore size and distribution of the prepared alumina ceramic membrane support were tested at room temperature using the bubble pressure method. The wetting solution was isopropanol. The test results are as follows: Figure 2 As shown, the average pore size of the obtained alumina ceramic film support is 0.424 μm, and the porosity is 43.38%. The flexural strength of the alumina ceramic film support was tested using a HYK-DPK digital display electric flexural strength tester and found to be 54 MPa. The microstructure of the material was observed using scanning electron microscopy, and the results are as follows. Figure 5 As shown.

[0056] (3) 1000g of alumina powder with an average particle size of 1μm and 100g of the alumina ceramic membrane sintering aid prepared in Example 3 were poured into a solid powder mixer. The alumina ceramic membrane support was prepared by kneading, mixing, aging, extrusion, drying, sintering, and cutting. The sintering temperature was 1150-1200℃. Using a PSDA-30 membrane material pore size analyzer, the pore size and distribution of the prepared alumina ceramic membrane support were tested at room temperature using the bubble pressure method. The wetting solution was isopropanol. The test results are as follows: Figure 3 As shown, the average pore size of the obtained alumina ceramic film support is 0.187 μm, and the porosity is 41.48%. The flexural strength of the alumina ceramic film support was tested using a HYK-DPK digital display electric flexural strength tester and found to be 63 MPa. The microstructure of the material was observed using scanning electron microscopy, and the results are as follows. Figure 6 As shown.

[0057] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention. Technologies not described in detail in this invention are known technologies.

Claims

1. An alumina ceramic film sintering aid, characterized in that, The alumina ceramic film sintering aid is composed of nano-silica and foaming powder, wherein the foaming powder comprises the following raw materials in parts by weight: 20 parts alumina powder, 50-80 parts potassium feldspar, 5-20 parts sodium feldspar, 0.1-1 part sodium carboxymethyl cellulose, 0.1-1 part sodium tripolyphosphate, 0.5-3 parts sodium hexametaphosphate, 0.3-1 part 1000 mesh manganese dioxide, 0.1-0.6 parts 1000 mesh silicon carbide, 100 parts water; The alumina ceramic film sintering aid is prepared by the following method: 1) Preparation of foamed powder: Take alumina powder, potassium feldspar, sodium feldspar, sodium carboxymethyl cellulose, sodium tripolyphosphate, sodium hexametaphosphate, 1000 mesh manganese dioxide, 1000 mesh silicon carbide and water, put them into a wet ball mill for mixing and ball milling. After ball milling, the mixture is granulated and dried in a spray drying tower. The resulting powder is passed through a 60 mesh sieve to obtain foamed powder. 2) Preparation of sol-gel mixture: Take an equal mass of 30% concentration of silica sol from the foamed powder, pour it into a high-speed stirring tank, and stir for 10-24 hours to obtain the sol-gel mixture; 3) Preparation of alumina ceramic film sintering aid: The sol-gel mixture is dried at 120℃ for 10-24h, and then gradually fed into a Raymond mill for crushing. The resulting powder is passed through a 60-mesh sieve and then gradually fed into an air jet mill for classification. Powder with a particle size D50 of 0.5-3μm and a particle size distribution (D90-D10) / D50≤3.0 is collected, which is the alumina ceramic film sintering aid.

2. The alumina ceramic film sintering aid as described in claim 1, characterized in that, The mass ratio of the nano-silica to the foamed powder is 0.3:

1.

3. The alumina ceramic film sintering aid as described in any one of claims 1-2, characterized in that, The alumina powder has a particle size D50 of 0.5-5μm and a particle size distribution (D90-D10) / D50 ≤ 3.

0.

4. The alumina ceramic film sintering aid as described in claim 3, characterized in that, The mixing and ball milling time is 10-48 hours, and the ball milling speed is 5-10 r / min.

5. The alumina ceramic film sintering aid as described in claim 4 is used in the alumina ceramic film support and the alumina film slurry.

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