Monolithic co-fired multi-phase ceramic membrane and method of making the same

Abstract

The application relates to the technical field of ceramic membrane preparation, in particular to a one-step co-sintering composite ceramic membrane and a preparation method thereof. The preparation method comprises the following steps: (1) uniformly mixing aluminum hydroxide, silicon dioxide, a sintering aid and a binding agent to obtain a support slurry; (2) performing dry pressing after sieving and drying the support slurry to obtain a mullite whisker support green body; (3) uniformly mixing zirconium oxide, a dispersing agent and the binding agent, and spraying the obtained zirconium oxide slurry onto the mullite whisker support green body; and (4) sintering the mullite whisker support green body after drying to obtain the one-step co-sintering composite ceramic membrane. The mullite whisker support with high permeability and high porosity is constructed by in-situ synthesis of mullite whiskers, the high-precision zirconia nano separation layer is prepared on the support, the interface bonding strength is improved by adjusting the sintering shrinkage parameters between the layers, the ceramic membrane is one-step co-sintered, and the purposes of improving the permeability, improving the separation precision and reducing the preparation cost are met.

Description

Technical Field

[0001] This invention relates to the field of ceramic membrane preparation technology, specifically to a one-time co-fired multiphase ceramic membrane and its preparation method. Background Technology

[0002] The increasingly serious water pollution problem exacerbates water scarcity and even threatens human survival. Oily wastewater, in particular, is a serious type of water pollution due to its large volume and wide range of sources. Membrane separation technology, relying on the sieving effect of porous materials, can achieve highly efficient separation of oily wastewater.

[0003] Currently, various membrane materials are used in oil-water separation processes, such as PVDF membranes, polyarylsulfone membranes, alumina membranes, and titanium mesh. Compared with polymer and metal materials, ceramic separation membranes have higher thermal stability, chemical stability, mechanical strength, and longer service life, showing better development prospects in complex and harsh processing environments. However, low permeation flux, complex preparation processes, and high costs severely restrict the widespread application of ceramic membranes. Compared with traditional particle-stacking ceramic membranes, ceramic membranes constructed from ceramic whiskers have higher porosity and more optimized pore structure, which can effectively improve the permeability of the membrane material. In addition, traditional preparation processes usually require multiple molding-drying-sintering processes, resulting in long production cycles and high energy consumption, further increasing the manufacturing cost of ceramic membranes. Therefore, simplifying the traditional multiple sintering process into a one-step low-temperature co-firing technology can reduce the energy consumption and cost of ceramic membrane production. Summary of the Invention

[0004] To address the technical problems of traditional ceramic membrane preparation processes that typically require multiple molding-drying-sintering steps, resulting in long production cycles and high energy consumption, this invention provides a mullite whisker-nanozirconia multiphase ceramic membrane and its preparation method. The method involves constructing a high-permeability, high-porosity mullite whisker support through in-situ synthesis of mullite whiskers, and then preparing a high-precision zirconia nano-separation layer on the support. By adjusting the interlayer sintering shrinkage parameters, the interfacial bonding strength is improved, thereby achieving one-step co-firing of the ceramic membrane. This achieves the goals of increasing permeability, improving separation accuracy, and reducing preparation costs.

[0005] In a first aspect, the present invention provides a method for preparing a one-time co-fired multiphase ceramic membrane, comprising the following steps:

[0006] (1) A wet ball milling method is used to mix aluminum hydroxide, silicon dioxide, sintering aid and binder in a mass ratio of 70~80:15~20:5~25:0.5~1 to obtain a support slurry;

[0007] (2) The support slurry is sieved, dried and then dry-pressed to obtain a mullite whisker support blank;

[0008] (3) Using a wet ball milling method, zirconium oxide, dispersant and binder are mixed evenly in a mass ratio of 96-98:1-2:1-2 to obtain zirconium oxide slurry, and the zirconium oxide slurry is sprayed onto the mullite whisker support blank.

[0009] (4) The mullite whisker support blank processed in step (3) is dried and then sintered to obtain a mullite whisker / zirconia composite film.

[0010] Furthermore, the sintering aid is aluminum fluoride. During the sintering process, the sintering aid works together with aluminum hydroxide particles and silicon dioxide particles to form mullite whiskers, resulting in a mullite whisker support with high porosity.

[0011] Furthermore, the binder is sodium carboxymethyl cellulose, which has a molecular weight of 10,000 to 16,000 and a purity greater than 98%.

[0012] Furthermore, the dispersant is polyacrylic acid or sodium hexametaphosphate.

[0013] Further, step (1) specifically involves: dissolving the binder in water by stirring, then adding aluminum hydroxide particles, silicon dioxide particles and sintering aid in sequence, and mixing them evenly by wet ball milling.

[0014] Furthermore, the purity of the aluminum hydroxide particles and silicon dioxide particles is greater than 99%.

[0015] Furthermore, the drying method in step (2) is rotary drying.

[0016] Further, step (3) specifically involves: dispersing the dispersant in water, then adding zirconium oxide particles and binder in sequence, and mixing them evenly using wet ball milling.

[0017] Furthermore, the mullite whisker support voxel treated in step (3) is dried at 20~25℃ for 24~48h.

[0018] Furthermore, in step (4), the sintering temperature is 1200~1600℃, the sintering time is 2~4h, and the heating rate is 2~5℃ / min.

[0019] Secondly, the present invention provides a single-fired multiphase ceramic film prepared by the above preparation method, comprising a mullite whisker support and a zirconium oxide nano-separation layer disposed on the mullite whisker support.

[0020] Furthermore, the mullite whisker support has a porosity of 50% to 70%, an average pore size of 1.0 to 3.5 μm, a compressive strength of 100 to 150 MPa, and a flexural strength of 15 to 30 MPa.

[0021] Furthermore, the permeation flux of the mullite whisker-nanozirconia multiphase ceramic membrane is 2000~3500 L·m. -2 ·h -1 The separation accuracy is 20~80nm.

[0022] The beneficial effects of this invention are as follows:

[0023] (1) The pore size of the whisker support layer is affected by three adjustment mechanisms: the radial size of the whisker, the pore segmentation mechanism, and the pore compression mechanism. This invention achieves adjustable pore size and optimizes pore structure by limiting the amount of aluminum hydroxide, silicon dioxide, sintering aid and binder in the support, thereby improving the porosity and permeability of the support; the separation accuracy of the ceramic membrane is improved by using nano-zirconia as a separation layer.

[0024] (2) This invention achieves one-step co-firing of ceramic membranes by controlling the composition of the support and membrane material, thereby reducing the cost of ceramic membranes;

[0025] (3) The mullite whisker / zirconia composite membrane prepared by the present invention has strong interfacial bonding strength and features both high throughput and high precision. It has broad application value and prospects in industries such as oil-water separation, new energy, and biomedicine. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 This is a schematic diagram of the structure of the mullite whisker-nanozirconia composite ceramic film of the present invention.

[0028] Figure 2 This is a photograph of the surface microstructure of the mullite whisker-nanozirconia composite ceramic film prepared in Example 2 of the present invention.

[0029] Figure 3 This is a cross-sectional microstructure photograph of the mullite whisker-nanozirconia composite ceramic film prepared in Example 2 of the present invention.

[0030] In the figure, 1-mullite whisker support, 2-zirconia nanolayer. Detailed Implementation

[0031] To enable those skilled in the art to better understand the technical solutions of this invention, the technical solutions of the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this invention.

[0032] In the following examples, the aluminum hydroxide particles and silica particles used have a purity greater than 99%; the sintering aid is aluminum fluoride; the binder is sodium carboxymethyl cellulose, which has a molecular weight of 10,000 to 16,000 and a purity greater than 98%; and the dispersant is polyacrylic acid.

[0033] Example 1

[0034] A one-time co-fired mullite whisker-zirconia nanocomposite ceramic film, comprising a mullite whisker support and a zirconia nano-separation layer disposed on the mullite whisker support, is prepared according to the following method:

[0035] (1) Disperse the binder in warm water, then add aluminum hydroxide particles, silica particles and sintering aid in sequence, and mix them evenly by wet ball milling. The mass ratio of aluminum hydroxide, silica, sintering aid and binder is 70:20:10:0.5 to obtain the support slurry;

[0036] (2) The support slurry is sieved, dried by rotary evaporation, and then pressed into shape to obtain a mullite whisker support blank. After drying, it is placed in a vacuum drying oven for later use.

[0037] (3) Stir and disperse the binder in warm water, then add zirconium oxide particles and dispersant in sequence, and mix evenly by wet ball milling. The mass ratio of zirconium oxide, dispersant and binder is 98:1:1 to obtain zirconium oxide slurry. Spray the zirconium oxide slurry onto the mullite whisker support blank.

[0038] (4) The mullite whisker support blank after step (3) is dried at 25°C for 24 hours, and then transferred to a high-temperature sintering furnace and co-fired at 1400°C for 2 hours at a heating rate of 5°C / min to obtain a mullite whisker / zirconia composite film.

[0039] The permeation flux of the mullite whisker-nanozirconia composite ceramic membrane was measured to be 2800 L·m. -2 ·h -1 The separation accuracy is 70nm, the porosity of the mullite whisker support is 62%, the average pore size is 2.4μm, the compressive strength is 117MPa, and the flexural strength is 24MPa.

[0040] Example 2

[0041] A one-time co-fired mullite whisker-zirconia nanocomposite ceramic film, comprising a mullite whisker support and a zirconia nano-separation layer disposed on the mullite whisker support, is prepared according to the following method:

[0042] (1) Disperse the binder in warm water, then add aluminum hydroxide particles, silica particles and sintering aid in sequence, and mix them evenly by wet ball milling. The mass ratio of aluminum hydroxide, silica, sintering aid and binder is 80:10:15:1 to obtain the support slurry.

[0043] (2) The support slurry is sieved, dried by rotary evaporation, and then pressed into shape to obtain a mullite whisker support blank. After drying, it is placed in a vacuum drying oven for later use.

[0044] (3) Stir and disperse the binder in warm water, then add zirconium oxide particles and dispersant in sequence, and mix evenly by wet ball milling. The mass ratio of zirconium oxide, dispersant and binder is 97:1:2 to obtain zirconium oxide slurry. Spray the zirconium oxide slurry onto the mullite whisker support blank.

[0045] (4) The mullite whisker support blank after step (3) is dried at 20°C for 36 hours and then transferred to a high-temperature sintering furnace and co-fired at 1300°C for 3 hours at a heating rate of 2°C / min to obtain a mullite whisker / zirconia composite film.

[0046] The permeation flux of the mullite whisker-nanozirconia composite ceramic membrane was measured to be 3100 L·m. -2 ·h -1 The mullite whisker support has a porosity of 58%, an average pore size of 3.0 μm, a compressive strength of 124 MPa, and a flexural strength of 26 MPa.

[0047] The surface and cross-sectional morphology of the mullite whisker-zirconia nanocomposite ceramic film prepared in Example 2 were observed. Figure 2 As shown, the pore size (separation precision) of the zirconia separation layer is approximately 50 nm, making it applicable to various microfiltration and ultrafiltration fields. Figure 3 As shown, the ceramic membrane consists of a mullite fiber support and a zirconium oxide separation layer.

[0048] The mullite fiber support prepared by the method of this invention has the characteristics of high porosity and high flux compared with the support formed by particle stacking, while the zirconia separation layer has the characteristics of high separation precision. Since the mullite support and the zirconia separation layer have the same sintering temperature, this multiphase ceramic membrane can be co-fired in one step, solving the technical problem of traditional ceramic membranes where the support and separation layer have different sintering temperatures, requiring two sintering processes.

[0049] Although the present invention has been described in detail with reference to the accompanying drawings and preferred embodiments, the present invention is not limited thereto. Various equivalent modifications or substitutions can be made to the embodiments of the present invention by those skilled in the art without departing from the spirit and essence of the invention, and such modifications or substitutions should all be within the scope of the present invention. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should also be covered within the protection scope of the present invention.

Claims

1. A method for preparing a one-time co-fired multiphase ceramic membrane, characterized in that, Includes the following steps: (1) A wet ball milling method is used to mix aluminum hydroxide, silicon dioxide, sintering aid and binder in a mass ratio of 70~80:15~20:5~25:0.5~1 to obtain a support slurry. The sintering aid is aluminum fluoride. (2) The support slurry is sieved, dried and then dry-pressed to obtain a mullite whisker support blank; (3) Using a wet ball milling method, zirconium oxide, dispersant and binder are mixed evenly in a mass ratio of 96~98:1~2:1~2 to obtain zirconium oxide slurry, and the zirconium oxide slurry is sprayed onto the mullite whisker support blank. (4) The mullite whisker support blank after step (3) is dried and sintered at a temperature of 1200~1600℃ for 2~4h and a heating rate of 2~5℃ / min to obtain a mullite whisker / zirconia composite film.

2. The preparation method according to claim 1, characterized in that, The binder is sodium carboxymethyl cellulose, which has a molecular weight of 10,000 to 16,000 and a purity greater than 98%.

3. The preparation method according to claim 1, characterized in that, The dispersant is polyacrylic acid or sodium hexametaphosphate.

4. The preparation method according to claim 1, characterized in that, Step (3) specifically involves: dispersing the dispersant in water, then adding zirconium oxide particles and binder in sequence, and mixing them evenly using wet ball milling.

5. The preparation method according to claim 1, characterized in that, The mullite whisker support matrix after step (3) is dried at 20~25℃ for 24~48h.

6. A one-time co-fired multiphase ceramic membrane prepared by the preparation method according to any one of claims 1 to 5, characterized in that, It includes a mullite whisker support and a zirconium oxide nano-separation layer disposed on the mullite whisker support.

7. The single-fired multiphase ceramic membrane as described in claim 6, characterized in that, The porosity of the mullite whisker support is 50%~70%, the average pore size is 1.0~3.5μm, the compressive strength is 100~150MPa, and the flexural strength is 15~30MPa.

8. The single-fired multiphase ceramic membrane as described in claim 6, characterized in that, The permeation flux of the mullite whisker-nanozirconia composite ceramic membrane is 2000~3500 L·m. -2 ·h -1 The separation accuracy is 20-80nm.

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