A filtration coating, its preparation method and use

Abstract

The application belongs to the technical field of filtration, and discloses a filter coating, a preparation method and application thereof. The preparation raw materials of the filter coating include stainless steel powder, sintering aids, resin and resin aids; the stainless steel powder includes stainless steel powder A with a particle size of 12-20 mu m, stainless steel powder B with a particle size of 5-8 mu m and stainless steel powder C with a particle size of 0.5-2 mu m. The preparation raw materials of the filter coating contain three kinds of stainless steel powder with specific particle sizes, and are compounded with sintering aids, resin and resin aids; after sintering, sintering necks are formed between the stainless steel powders, the filter coating is arranged on the surface of a traditional filter part (porous support body) such as a filter tube and a filter plate, a filter layer with pores of 0.2-2 mu m can be formed on the porous support body, the filtration precision is significantly improved, and the filter coating has good bonding force with the porous support body.

Description

Technical Field

[0001] This invention belongs to the field of filtration technology, and specifically relates to a filter coating, its preparation method, and its application. Background Technology

[0002] Stainless steel filter tubes, filter elements, and filter plates are widely used components in wastewater treatment and liquid filtration in the food and chemical industries. Traditionally, stainless steel filter components are formed by sintering stainless steel powder directly. The particle size of the powder determines the porosity of the filter component, i.e., the filtration precision. However, the filtration precision of filter components obtained in this way is typically above 5μm. With industrial development, there are increasingly higher requirements for the precision of filter components, necessitating filters with smaller pores and higher filtration precision. Because the sintering of ultrafine powder is very difficult to control, the industry currently cannot achieve products with higher filtration precision through sintering.

[0003] Therefore, it is essential to develop products with higher filtration accuracy. Summary of the Invention

[0004] The present invention aims to at least solve one of the technical problems existing in the prior art. To this end, the present invention provides a filter coating, its preparation method, and its application. The filter coating of the present invention can significantly improve filtration accuracy and has good adhesion to a porous support.

[0005] The first aspect of the present invention provides a filter coating, wherein the raw materials for preparing the filter coating include: stainless steel powder, sintering aid, resin and resin additive; wherein the stainless steel powder includes stainless steel powder A with a particle size of 12-20 μm, stainless steel powder B with a particle size of 5-8 μm and stainless steel powder C with a particle size of 0.5-2 μm.

[0006] In some embodiments of the present invention, the raw materials for preparing the filter coating, by weight percentage, include: 50%-80% stainless steel powder, 1%-8% sintering aid, 5%-30% resin, and 0.5%-5% resin additives.

[0007] In some embodiments of the present invention, the raw materials for preparing the filter coating, by weight percentage, include: 60%-75% stainless steel powder, 1%-5% sintering aid, 20%-30% resin, and 1%-3% resin additives.

[0008] In some embodiments of the present invention, the mass ratio of stainless steel powder A, stainless steel powder B, and stainless steel powder C is (3-5):(2-3.5):(2-4.5). The present invention utilizes a specific combination of large, medium, and small particle sizes, wherein large particle sizes block the pores of the porous support, medium particle sizes are embedded in the gaps between the large particle sizes, and finally, small particle sizes are combined to form pores of 0.2-2 μm.

[0009] In some embodiments of the present invention, the stainless steel powder includes at least one of 210, 316L, 17-4, 304 and 901.

[0010] In some embodiments of the present invention, the vacuum sintering aid includes at least one of silicon carbide, sodium borate, copper phosphide, iron boride, and iron boromolybdenide.

[0011] In some embodiments of the present invention, the resin is an acrylic resin and / or epoxy resin with a viscosity of 300-1500 CPS at 25°C and a molecular weight of 500-2000. The higher the molecular weight of the resin, the higher the viscosity, making debinding during sintering more difficult. If the molecular weight is too low, the slurry lacks thixotropy and is difficult to level. The present invention limits the viscosity to obtain good coating application performance; if the viscosity is too high, the coating thickness will be uneven; if the viscosity is too low, the fluidity will be too high, and the fine powder portion of the slurry will easily leak from the porous support.

[0012] In some embodiments of the present invention, the resin includes at least one of 203PB89B, 3AB91W, 1AB911Y, 3ASB0901B and 3AE30W.

[0013] In some embodiments of the present invention, the resin additive includes at least one of WD010, WD025, WD019, WD091, and WD026. The resin additives added in the present invention mainly serve functions such as dispersion, leveling, and defoaming.

[0014] A second aspect of the present invention provides a method for preparing the filter coating described herein, comprising the following steps:

[0015] The stainless steel powder, sintering aid, resin and resin additives are mixed to obtain a metal slurry, which is then dried and vacuum sintered to obtain the filter coating.

[0016] In some embodiments of the present invention, the drying temperature is 100℃-150℃; and / or, the vacuum sintering temperature is 1150℃-1280℃; and / or, the vacuum sintering time is 1h-5h; and / or, the vacuum degree of the vacuum sintering is <0.05pa.

[0017] In some embodiments of the present invention, the mixing method includes, but is not limited to, ball milling.

[0018] In some embodiments of the present invention, the mass ratio of stainless steel powder to grinding balls is 1:(1-3); the rotation speed of the ball mill is 300-400 r / min; and the ball milling time is 30-120 min.

[0019] In some embodiments of the present invention, the viscosity of the metal slurry at 25°C is 1000-3000 CPS. A low viscosity of the metal slurry can easily lead to leakage, while a high viscosity results in poor coating leveling, uneven thickness, and ultimately affects the filtration accuracy of the filter coating.

[0020] A third aspect of the present invention provides a filter component, the filter component comprising a porous support and a filter coating as described in the present invention, the filter coating being disposed on the surface of the porous support.

[0021] In some embodiments of the present invention, the porous support is an iron-based porous support.

[0022] In some embodiments of the present invention, the average pore diameter of the porous support is 5-10 μm.

[0023] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0024] The raw materials for preparing the filter coating of this invention contain three stainless steel powders with specific particle sizes, and are compounded with sintering aids, resins and resin additives. After sintering, sintering necks are formed between the stainless steel powders. This filter coating is applied to the surface of traditional filter tubes, filter plates and other filter components (porous supports), and can form a filter layer with pores of 0.2-2μm on the porous support, which significantly improves the filtration accuracy and has good bonding force with the porous support. Attached Figure Description

[0025] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0026] Figure 1 A scanning electron microscope image of the filter component in Application Example 1;

[0027] Figure 2 This is a photograph of the filter component from Application Example 1 after an adhesion test.

[0028] Figure 3 This is a photograph of the filter element used in Comparative Example 1 after an adhesion test. Detailed Implementation

[0029] The present invention will be further described in detail below through specific embodiments. Unless otherwise specified, the raw materials, reagents, or apparatus used in the embodiments can be obtained from conventional commercial sources or by existing technical methods. Unless otherwise specified, the experimental or testing methods are conventional methods in the art.

[0030] The following examples use commercially available iron-based porous supports with an average pore diameter of 10 μm.

[0031] Example 1

[0032] This embodiment provides a filter coating composed of the following raw materials by mass percentage: 70% 316L stainless steel powder, 1% silicon carbide, 1.5% copper phosphide, 25% 3PB89B resin, 1.5% WD010 resin additive, and 1% WD026 resin additive; wherein the stainless steel powder is composed of stainless steel powder A with a particle size of 15μm, stainless steel powder B with a particle size of 6μm, and stainless steel powder C with a particle size of 1μm in a mass ratio of 3.5:3.5:3.

[0033] Application Example 1

[0034] This application example provides a tubular filter element, which includes an iron-based porous support and a filter coating of Example 1, wherein the filter coating of Example 1 is disposed on the surface of the iron-based porous support.

[0035] The method for preparing this filter component includes the following steps:

[0036] S1. Grinding: Add each of the preparation raw materials in Example 1 into a ball mill jar according to the ratio, ball mill at 300 r / min for 60 min, and then filter to obtain a metal slurry with a viscosity of 1000-3000; wherein, the mass ratio of 316L stainless steel powder to grinding balls is 1:2.

[0037] S2. Coating and drying: The metal slurry is coated onto the iron-based porous support using a peristaltic pump, allowing excess metal slurry to flow away and maintaining a uniform coating thickness. The slurry is then hung to dry at 100°C to obtain the green body.

[0038] S3. Sintering: The green body is sintered in a vacuum atmosphere (0.03 Pa) at 1180°C for 3 hours to obtain the filter component.

[0039] The scanning electron microscope image of the filter component obtained in this application example is as follows: Figure 1 As shown, 1 is an iron-based porous support; 2 is a filter coating with a thickness of 24.81 μm. The average pore size of the filter component is 1.2 μm.

[0040] Example 2

[0041] This embodiment provides a filter coating composed of the following raw materials in weight percentages: 65% 304 stainless steel powder, 1% ferric boromolybdenum, 2% sodium borate, 30% 1AB911Y resin, 1% WD010 resin additive, and 1% WD026 resin additive; wherein the stainless steel powder is formed by mixing stainless steel powder A with a particle size of 15 μm, stainless steel powder B with a particle size of 6 μm, and stainless steel powder C with a particle size of 1 μm in a weight ratio of 3:3:4.

[0042] Application Example 2

[0043] This application example provides a tubular filter element, which includes an iron-based porous support and a filter coating of Example 2, wherein the filter coating of Example 2 is disposed on the surface of the iron-based porous support.

[0044] The method for preparing this filter component includes the following steps:

[0045] S1. Grinding: Add each of the preparation raw materials in Example 2 into a ball mill jar according to the ratio, ball mill at 300 r / min for 60 min, and then filter to obtain a metal slurry with a viscosity of 1000-3000; wherein, the mass ratio of 304 stainless steel powder to grinding balls is 1:2.

[0046] S2. Coating and drying: The metal slurry is coated onto the iron-based porous support using a peristaltic pump, allowing excess metal slurry to flow away and maintaining a uniform coating thickness. The slurry is then hung to dry at 100°C to obtain the green body.

[0047] S3. Sintering: The green body is sintered in a vacuum atmosphere (0.03 Pa) at 1180°C for 3 hours to obtain the filter component.

[0048] The filter element obtained in this application example has a filter coating thickness of approximately 18 μm and an average pore size of 0.8 μm.

[0049] Example 3

[0050] This embodiment provides a filter coating composed of the following raw materials by mass percentage: 65% 17-4 stainless steel powder, 1.5% silicon carbide, 1.5% iron boride, 30% 3AE30W resin, 1% WD010 resin additive, and 1% WD026 resin additive; wherein the stainless steel powder is composed of stainless steel powder A with a particle size of 15 μm, stainless steel powder B with a particle size of 6 μm, and stainless steel powder C with a particle size of 1 μm in a mass ratio of 3:3.5:4.5.

[0051] Application Example 3

[0052] This application example provides a tubular filter element, which includes an iron-based porous support and a filter coating of Example 3, wherein the filter coating of Example 3 is disposed on the surface of the iron-based porous support.

[0053] The method for preparing this filter component includes the following steps:

[0054] S1. Grinding: Add the raw materials prepared in Example 3 into a ball mill jar according to the proportions, ball mill at 300 r / min for 60 min, and then filter to obtain a metal slurry with a viscosity of 1000-3000; wherein, the mass ratio of 17-4 stainless steel powder to grinding balls is 1:2.

[0055] S2. Coating and drying: The metal slurry is coated onto the iron-based porous support using a peristaltic pump, allowing excess metal slurry to flow away and maintaining a uniform coating thickness. The slurry is then hung to dry at 100°C to obtain the green body.

[0056] S3. Sintering: The green body is sintered in a vacuum atmosphere (0.03 Pa) at 1180°C for 3 hours to obtain the filter component.

[0057] The filter element obtained in this application example has a filter coating thickness of approximately 16 μm and an average pore size of 0.4 μm.

[0058] Example 4

[0059] This embodiment provides a filter coating composed of the following raw materials by mass percentage: 70% 316L stainless steel powder, 1% sodium borate, 1.5% copper phosphide, 25% 3AB91W resin, 1.5% WD010 resin additive, and 1% WD026 resin additive; wherein the stainless steel powder is composed of stainless steel powder A with a particle size of 15μm, stainless steel powder B with a particle size of 6μm, and stainless steel powder C with a particle size of 1μm in a mass ratio of 4:3.5:2.5.

[0060] Application Example 4

[0061] This application example provides a plate-shaped filter component, which includes an iron-based porous support and a filter coating of Example 4, wherein the filter coating of Example 4 is disposed on the surface of the iron-based porous support.

[0062] The method for preparing this filter component includes the following steps:

[0063] S1. Grinding: Add each of the preparation raw materials in Example 4 into a ball mill jar according to the ratio, ball mill at 300 r / min for 60 min, and then filter to obtain a metal slurry with a viscosity of 1000-3000; wherein, the mass ratio of 316L stainless steel powder to grinding balls is 1:2.

[0064] S2. Coating and drying: The metal slurry is coated onto the iron-based porous support using a peristaltic pump, allowing excess metal slurry to flow away and maintaining a uniform coating thickness. The slurry is then hung to dry at 100°C to obtain the green body.

[0065] S3. Sintering: The green body is sintered in a vacuum atmosphere (0.03 Pa) at 1180°C for 3 hours to obtain the filter component.

[0066] The filter element obtained in this application example has a filter coating thickness of approximately 21 μm and an average pore size of 1.5 μm.

[0067] Comparative Example 1 (The difference from Example 1 is that the raw materials for Comparative Example 1 lacked sintering aids)

[0068] This comparative example provides a filter coating composed of the following raw materials by mass percentage: 70% 316L stainless steel powder, 27.5% 3PB89B resin, 1.5% WD010 resin additive, and 1% WD026 resin additive; wherein the stainless steel powder is a mixture of stainless steel powder A with a particle size of 15 μm, stainless steel powder B with a particle size of 6 μm, and stainless steel powder C with a particle size of 1 μm in a mass ratio of 3.5:3.5:3.

[0069] Application Comparative Example 1

[0070] This comparative example provides a tubular filter element. The difference between this example and Example 1 is that the filter coating is the same as that of Example 1, and the preparation methods of the iron-based porous support and the filter element are the same as those of Example 1.

[0071] Comparative Example 2 (The difference from Example 1 is that the raw materials for Comparative Example 2 lacked resin additives)

[0072] This comparative example provides a filter coating composed of the following raw materials by mass percentage: 70% 316L stainless steel powder, 1% silicon carbide, 1.5% copper phosphide, and 27.5% 3PB89B resin; wherein the stainless steel powder is composed of stainless steel powder A with a particle size of 15 μm, stainless steel powder B with a particle size of 6 μm, and stainless steel powder C with a particle size of 1 μm in a mass ratio of 3.5:3.5:3.

[0073] Application Comparative Example 2

[0074] This comparative example provides a tubular filter element. The difference between this example and Example 1 is that the filter coating is the same as that of Comparative Example 2, and the preparation methods of the iron-based porous support and the filter element are the same as those of Example 1.

[0075] Comparative Example 3 (The difference from Example 1 is that the raw material for Comparative Example 3 is stainless steel powder with a particle size exceeding the specified range)

[0076] This comparative example provides a filter coating composed of the following raw materials by mass percentage: 70% 316L stainless steel powder, 1% silicon carbide, 1.5% copper phosphide, and 27.5% 3PB89B resin; wherein the stainless steel powder is composed of stainless steel powder A with a particle size of 30 μm, stainless steel powder B with a particle size of 25 μm, and stainless steel powder C with a particle size of 0.1 μm in a mass ratio of 3.5:3.5:3.

[0077] Application Comparative Example 3

[0078] This comparative example provides a tubular filter element. The difference between this example and Example 1 is that the filter coating is the same as that of Comparative Example 3, and the preparation methods of the iron-based porous support and the filter element are the same as those of Example 1.

[0079] The pore size of the filter components in Application Examples 1-4 and Comparative Examples 1-3, as well as the test results of the bonding performance between the filter coating and the iron-based porous support, are shown in Table 1.

[0080] Table 1

[0081]

[0082] The actual image of the filter component in Application Example 1 after adhesion testing is shown below. Figure 2 As shown, the filter coating and the iron-based porous support are integrated without peeling, demonstrating a good bond. A photograph of the filter component from Comparative Example 1 after adhesion testing is shown below. Figure 3 As shown, the filter coating has obvious peeling; the filter coating of Comparative Example 2 has poor adhesion; and the filter component of Comparative Example 3 has an excessively large average pore size, which does not meet the requirements.

[0083] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the described embodiments. Those skilled in the art can make various equivalent modifications or substitutions without departing from the spirit of the present invention, and these equivalent modifications or substitutions are all included within the scope defined by the claims of this application.

Claims

1. A filter element, characterized in that, The filter component includes a porous support and a filter coating, wherein the filter coating is disposed on the surface of the porous support. The raw materials for preparing the filter coating include: stainless steel powder, sintering aid, resin and resin additives; the stainless steel powder includes stainless steel powder A with a particle size of 12-20μm, stainless steel powder B with a particle size of 5-8μm and stainless steel powder C with a particle size of 0.5-2μm. The sintering aid is at least one of silicon carbide, sodium borate, copper phosphide, iron boride, and iron boromolybdenide; The resin additive is at least one of WD010, WD025, WD019, WD091 and WD026; The average pore diameter of the porous support is 5-10 μm.

2. The filter element according to claim 1, characterized in that, The raw materials for preparing the filter coating, by weight percentage, include: 50%-80% stainless steel powder, 1%-8% sintering aid, 5%-30% resin, and 0.5%-5% resin additives.

3. The filter element according to claim 2, characterized in that, The raw materials for preparing the filter coating, by weight percentage, include: 60%-75% stainless steel powder, 1%-5% sintering aid, 20%-30% resin, and 1%-3% resin additives.

4. The filter element according to claim 1, characterized in that, The mass ratio of stainless steel powder A, stainless steel powder B, and stainless steel powder C is (3-5):(2-3.5):(2-4.5).

5. The filter element according to claim 1, characterized in that, The resin is an acrylic resin and / or epoxy resin with a viscosity of 300-1500 CPS at 25°C and a molecular weight of 500-2000.

6. The filter element according to claim 1, characterized in that, The filter coating is prepared by a method including the following steps: The stainless steel powder, sintering aid, resin and resin additives are mixed to obtain a metal slurry, which is then dried and vacuum sintered to obtain the filter coating.

7. The filter element according to claim 6, characterized in that, The drying temperature is 100℃-150℃; and / or the vacuum sintering temperature is 1150℃-1280℃; and / or the vacuum sintering time is 1h-5h; and / or the vacuum degree of the vacuum sintering is <0.05pa.

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