3D-printed ceramic filter and preparation method thereof and preparation slurry thereof

Abstract

The application provides a 3D printing ceramic filter and a preparation method of a slurry and the filter, and the composition of the filter comprises 90-92wt% of ZrO2, 4.7-4.8wt% of MgO, 1.9-2.0wt% of HfO2 and 1.4-1.5wt% of SiO2. The application improves the exposure precision of the slurry by adjusting the type and ratio of monomers and the adding amount of initiators, thereby improving the porosity of the filter and the flow rate when the filter is used to filter the metal liquid. The yield of the 3D printing ceramic filter is high, and reaches more than 80%. The addition of the organic silicon modified epoxy resin in the ceramic slurry improves the printing efficiency. The anti-settling wax can solve the problem of fast slurry settlement and improve the crack problem existing in the appearance.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of 3D printing, and particularly relates to a 3D printed ceramic filter, a slurry for preparing the same and a preparation method. BACKGROUND

[0002] In the foundry industry, a foam ceramic filter is usually selected to filter a high-temperature metal solution because the porous structure of the foam ceramic filter can filter out a large amount of impurities contained in the solution, thereby purifying the metal liquid. The basic materials of the foam ceramic filter include silicon carbide, zirconia and alumina. The conventional preparation method of the foam ceramic filter is generally to use polyurethane foam plastic as a precursor, dip a refractory slurry, extrude, dry and then obtain by high-temperature sintering. The foam ceramic filter prepared by this method has the following shortcomings: 1. After dipping the refractory slurry, the excess slurry cannot be completely extruded during extrusion, resulting in a pore blockage phenomenon and low porosity of the filter; 2. Since the carrier is foamed polyurethane foam, the thickness of the foam inside the foam ceramic filter is not uniform, and the thinner part is prone to breakage; 3. Due to the limitation of the polyurethane foam plastic, the foam ceramic filter cannot be made into any shape, which cannot meet all requirements.

[0003] 3D printing is an additive manufacturing, and no mold is required in the manufacturing process. The 3D printing can be made into a shape and internal structure that meet various requirements, a plurality of holes can be designed between the inlet surface and the outlet surface of a single ceramic unit, the holes can be uniformly distributed and the size and spacing of the holes can be adjusted at will, and the holes can be adjusted according to different filtering requirements, thereby improving the filtering effect. However, the existing 3D printed filter has the problems of low slurry exposure precision and low printing efficiency. The exposure precision of the slurry refers to uniformly spreading the slurry on a cover glass, exposing according to a template, and then flushing away the remaining part of the excess slurry. The higher the fit degree of the remaining part of the excess slurry after flushing away and the template itself, the better the precision. The exposure precision of the slurry will directly affect the details of the printed model. Low precision will result in rough details of the printed model. For the filter, low exposure precision of the slurry will result in poor through holes, thereby affecting the flow rate of the metal liquid during filtration.

[0004] Chinese patent document CN112225580A (202010957990.3) discloses a photocured 3D printing zirconia foam ceramic filter and a preparation method thereof. The photocured 3D printing zirconia foam ceramic filter comprises 70-90% zirconia powder and 10-30% photocured resin by mass fraction. The 3D printing technology is combined with high-temperature-resistant zirconia ceramic material, and a porous polyurethane plastic carrier is not needed, so that a ceramic foam ceramic filter blank can be directly formed, and a zirconia foam ceramic filter is obtained through high-temperature sintering. The skeleton of the photocured 3D printing zirconia foam ceramic filter is a solid structure, has high strength and is not easy to break, and there is no problem of hole blockage caused by excess slurry between the skeletons, so that the opening rate is high and the filtering performance is guaranteed. Although the patent has a high opening rate, the exposure precision is low, the hole periphery is relatively rough, and the actual porosity is affected. SUMMARY

[0005] In order to solve the problems of low precision of the filter, poor porosity and slow metal liquid filtering flow rate caused by low slurry exposure precision of 3D printing, the application provides a 3D printing ceramic filter, a preparation slurry and a preparation method thereof.

[0006] In order to achieve the above-mentioned purpose, the application adopts the following technical scheme:

[0007] A 3D printing ceramic filter, the composition of the filter comprises 90-92wt% ZrO2, 4.7-4.8wt% MgO, 1.9-2.0wt% HfO2 and 1.4-1.5wt% SiO2. It also contains a small amount of Al2O3, CaO and TiO2.

[0008] The application also provides a mixed slurry for preparing the above-mentioned 3D printing ceramic filter, the slurry comprises the following components by weight: a photosensitive resin premix liquid composed of 5-15 parts of monomer a, 3-9 parts of monomer b, 2-6 parts of monomer c and 0.02-0.4 parts of an initiator, 0.7-2.7 parts of a dispersing agent and 70-90 parts of a zirconia mixture, wherein the zirconia mixture is composed of zirconia powder and magnesium oxide powder, and the content of the magnesium oxide powder is 2-10wt% of the zirconia mixture.

[0009] The monomer a and the monomer b are selected from two of the following: hydroxydiol diacrylate HDDA, tripropylene glycol diacrylate TPGDA, hydroxyethyl acrylate HEA, polyethylene glycol diacrylate PEG(200)DA and ethylene glycol dimethacrylate EGDMA.

[0010] The monomer c is selected from dimethyl methacrylate urea UDMA.

[0011] Preferably, the monomer a is hexanediol diacrylate HDDA, the monomer b is hydroxyethyl acrylate HEA, and the monomer c is dimethylamino methacrylate UDMA.

[0012] Preferably, the slurry comprises the following components by weight: 10-12 parts of monomer a, 6-8 parts of monomer b, 4-5 parts of monomer c, 1.5-1.6 parts of dispersant, 0.1-0.2 parts of initiator, and 75-80 parts of zirconia mixture.

[0013] Further preferably, the slurry comprises the following components by weight: 10 parts of monomer a, 6 parts of monomer b, 4 parts of monomer c, 1.6 parts of dispersant, 0.2 parts of initiator, and 80 parts of zirconia mixture. Preferably, the zirconia mixture contains 5wt% of magnesium oxide.

[0014] Preferably, the dispersant is selected from one of BYK111, BYK163, and BYK180, and further preferably BYK111.

[0015] Preferably, the initiator is selected from bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide and 2,4,6-trimethylbenzoyl-ditolylphosphine oxide, and further preferably bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide.

[0016] Preferably, the particle size of the zirconia mixture is 325-800 mesh, and further preferably 800 mesh.

[0017] Preferably, the mass ratio of the monomers (a+b+c) to the zirconia mixture is 10-30:90-70, the mass ratio of the initiator to the monomers (a+b+c) is 1:500-1:50, and further preferably 1:200-1:100, and the mass ratio of the dispersant to the zirconia mixture is 1:30-1:80, and preferably 1:50.

[0018] The present application solves the problems of low precision of 3D printing filters, poor porosity, and slow metal liquid filtration speed caused by low exposure precision of the slurry by using certain types and proportions of raw materials.

[0019] Preferably, the mixed slurry further contains 3-10% of silicone-modified epoxy resin based on the mass of the photosensitive resin premix, and the solid content of the silicone-modified epoxy resin is 50±1%. Without adding the silicone-modified epoxy resin, the printing time for one layer is 17s, and after adding the silicone-modified epoxy resin, the printing time for one layer is 15s. The addition of the silicone-modified epoxy resin improves the printing efficiency.

[0020] Preferably, the mixed slurry further contains a liquid sintering aid, and the liquid sintering aid accounts for 0.5-1.5wt% of the mass of the mixed slurry. The liquid sintering aid is polyethylene glycol.

[0021] Preferably, the mixed slurry further comprises anti-settling wax, and the anti-settling wax accounts for 1.5-2.5wt% of the mass of the mixed slurry. The anti-settling wax is polyamide wax. The anti-settling wax can solve the problem of rapid slurry settlement and improve the appearance of cracks and other problems.

[0022] Further preferably, the mixed slurry further comprises 1% of liquid sintering aid, 2% of anti-settling wax, and 5% of silicone-modified epoxy resin by mass of the mixed slurry.

[0023] The application also provides a preparation method of the 3D-printed ceramic filter.

[0024] (1) Preparing a mixed slurry: first, mixing monomer a, monomer b, monomer c, and initiator by using a planetary ball mill for 20-30 min to obtain a photosensitive resin premix; then adding zirconia mixture and dispersant and continuing to mix for 30-40 min to obtain a mixed slurry;

[0025] (2) Preparing a ceramic slurry: filtering the mixed slurry by using a suction filtration device, and then placing it in a vacuum pump to perform vacuumization for 10-20 min to prepare a ceramic slurry;

[0026] (3) 3D printing: using 3D modeling software to establish a 3D printing model of the ceramic filter, using the software provided by the printer to decompose the model into a series of slices with a thickness of 50-100 μm, inputting the established 3D printing model data into a DLP 3D printer, and setting the printing parameters: exposure power is 10-30 mw / cm 2 , the first layer printing time is 10-20 s, and the material laying thickness is 50-150 μm;

[0027] Scanning and solidifying the ceramic slurry according to the above printing parameters, and after the printing is completed, removing the ceramic filter from the forming table, and flushing away the excess slurry to prepare a ceramic filter blank;

[0028] (4) Sintering: heating the ceramic filter blank prepared by printing to 900-1200℃ at a heating rate of 1-2℃ / min, maintaining the temperature for 0.5-2 h, then heating to 1600-1700℃ at a heating rate of 0.5-2℃ / min, maintaining the temperature for 1-3 h, and naturally cooling to room temperature to obtain the 3D-printed ceramic filter.

[0029] Preferably, in step (1), the photosensitive resin premix is added with silicone-modified epoxy resin, liquid sintering aid, and anti-settling wax.

[0030] The application has the following beneficial effects:

[0031] (1) The present application improves the slurry exposure precision by adjusting the type and ratio of monomers and the addition amount of initiator, thereby improving the porosity of the filter and the flow rate during the filtration of the molten metal.

[0032] (2) The 3D printed ceramic filter provided by the present application has a high yield, which is more than 80%, and can further reach more than 98%.

[0033] (3) The addition of the organic silicon modified epoxy resin in the ceramic slurry of the present application improves the printing efficiency. The anti-settling wax can solve the problem of rapid slurry settling and improve the appearance and crack problems. BRIEF DESCRIPTION OF DRAWINGS

[0034] Figure 1 is the real picture of the 3D printed ceramic filter sample obtained in Comparative Example 1;

[0035] Figure 2 is the real picture of the 3D printed ceramic filter sample obtained in Example 1;

[0036] Figure 3 is the slurry prepared without adding anti-settling wax;

[0037] Figure 4 is the slurry prepared by adding anti-settling wax;

[0038] Figure 5 is the exposure precision effect picture of the ceramic slurry obtained in Example 1;

[0039] Figure 6 is the exposure precision effect picture of the ceramic slurry obtained in Comparative Example 2.

[0040] Figure 7 is the exposure template schematic diagram for slurry exposure precision. DETAILED DESCRIPTION

[0041] The embodiments of the present application will be described in detail below with specific examples. The specific conditions are not specified in the examples, and the conventional conditions or the conditions recommended by the manufacturer are used. The reagents or instruments used are not specified by the manufacturer, and are all conventional products that can be obtained by market purchase. Among them, the 3D printer used is purchased from Beijing Shiwai Technology Co., Ltd., the HDDA is from Shanghai Guangyi Chemical Co., Ltd., the HEA is from Guangzhou Yuanxin Material Co., Ltd., the UDMA is from Shandong Shoucheng Chemical Co., Ltd., the initiator is from Hubei Shenne Chemical Technology Co., Ltd., the zirconia is from Sanshang New Material Co., Ltd., the magnesium oxide is from Henan Wanshan New Material Technology Co., Ltd., and the dispersing agent is BYK-111 from Germany BYK. The organic silicon modified epoxy resin used is Shin-Etsu Chemical ES-1001N.

[0042] Example 1

[0043] A 3D printed ceramic filter is prepared according to the following method:

[0044] (1) Prepare a mixed slurry: first, put 10 parts by weight of hexanediol diacrylate HDDA, 6 parts by weight of hydroxyethyl acrylate HEA, 4 parts by weight of dimethylamino methacrylate UDMA photocuring monomer and 0.1 parts by weight of bis(2,4,6-trimethylbenzoyl) phenyl phosphine oxide photoinitiator into a ball mill tank, and mix them at normal temperature and pressure for 20 minutes using a planetary ball mill to obtain a photosensitive resin premix. Then add 80 parts by weight of mixed zirconia powder (containing 5wt% magnesium oxide), 1.6 parts by weight of dispersant BYK111, and continue to mix in the planetary ball mill for 40 minutes to obtain a mixed slurry.

[0045] (2) Prepare a ceramic slurry: filter the mixed slurry through a suction filtration device, then place it in a vacuum pump and vacuum for 20 minutes to obtain a ceramic slurry.

[0046] (3) 3D printing: use 3D modeling software to establish the required 3D printing model (model porosity 65-75%), use the 10dim software provided by the printer to decompose the model into a series of slices with a thickness of 75μm, input the established 3D printing model data into the DLP 3D printer, and set the printing parameters: exposure power 20mw / cm 2 , first layer printing time 18s, and material laying thickness 100μm. Place the ceramic slurry in the 3D printer cartridge, and scan and solidify according to the above printing parameters. After printing, remove the ceramic filter from the forming table, rinse off the excess slurry, and obtain the ceramic filter blank.

[0047] (4) Sintering: heat the ceramic filter blank prepared by printing to 1100℃ at a heating rate of 1.5℃ / min, keep for 1h, then heat to 1650℃ at a heating rate of 1℃ / min, keep for 2h, and then naturally cool to room temperature to obtain the 3D printed ceramic filter.

[0048] The preparation methods of other examples and comparative examples are the same as those of Example 1. The preparation parameters of each example and comparative example are summarized in Table 1. The parameters not recorded in Table 1 are the same as those of Example 1.

[0049] Example 2

[0050] Different from Example 1, an organic silicon modified epoxy resin (Shin-Etsu Chemical ES-1001N) is added to the photosensitive resin premix of step (1), and the amount of organic silicon modified epoxy resin added is 5% of the weight of the photosensitive resin premix.

[0051] Example 3

[0052] Different from example 1, the proportion of mixed slurry was changed, as shown in Table 1.

[0053] Example 4

[0054] Different from example 1, the initiator was changed to 0.2 parts by weight, and the silicone-modified epoxy resin (Shin-Etsu Chemical ES-1001N), polyethylene glycol, and polyamide wax were added to the photosensitive resin premix solution of step (1) to obtain a mixed slurry. The silicone-modified epoxy resin accounted for 5% of the weight of the photosensitive resin premix solution, the polyethylene glycol accounted for 1% of the total weight of the mixed slurry, and the polyamide wax accounted for 2% of the total weight of the mixed slurry.

[0055] Comparative Example 1

[0056] Different from example 1, the monomer c was trimethylolpropane triacrylate TMPTA.

[0057] Comparative Example 2

[0058] Different from example 1, the proportion of mixed slurry and sintering parameters were changed, and the specific process is shown in Table 1.

[0059] Table 1 is the preparation process parameters of each example and comparative example

[0060]

[0061]

[0062] The performance of the ceramic slurry or ceramic filter prepared in the above examples and comparative examples was evaluated, and the results are shown in Table 2:

[0063] Filter performance evaluation method:

[0064] Filter flow: 1 square centimeter of metal liquid flow.

[0065] Exposure accuracy: The slurry was spread on a glass slide and placed in the center of the printer glass plate. An exposure template (as shown in Figure Seven ) was selected for exposure. After exposure, the excess slurry was washed away, and the size of the hollowed-out part was measured with a vernier caliper. The closer the size to the size given by the exposure template, the better the exposure effect. In the present application, the exposure accuracy is arranged in the order of high, relatively high, general, relatively poor, and poor.

[0066] Yield: 100 filters were sintered, and the number of filters with intact appearance accounted for a percentage of the total number.

[0067] Settling rate: The slurry was poured into a test tube and left to stand for 24 h. The height of the layered slurry / the total height of the slurry x 100%.

[0068] Curing time: the time (s) used for curing one layer.

[0069] Filter porosity: The porosity refers to the ratio of the volume of pores in the porous body to the total volume of the porous body. The instrument used for porosity detection is an electronic balance, and the porosity is determined according to the porosity determination method in GB / T25139. The greater the porosity of the filter, the greater the flow rate of the filtering of the metal liquid, but if the porosity is too large, the filtering effect will also be poor.

[0070] Table 2 Performance evaluation results of the ceramic slurry or ceramic filter prepared in the examples and the comparative examples

[0071] Number Filter porosity Sedimentation rate Exposure accuracy Curing time Yield Example 1 72.8％ 10％ Higher 18s 88％ Example 2 74.6％ 10％ High 15S 87％ Example 3 72.3％ 10％ High 17S 88％ Example 4 73.3 3％ Higher 15S 92％ Comparative Example 1 62.5 10％ Higher 18s 53％ Comparative Example 2 65.3％ 10％ Poor 18s 60％

[0072] As can be seen from Tables 1 and 2, the examples have improved printing accuracy, yield, sedimentation rate and printing efficiency compared with the comparative examples.

[0073] The composition of the filter is detected by a fluorescence analyzer. The composition of the filter obtained by the present application is shown in Table 3 as follows:

[0074] Table 3 Composition detection results of the filter obtained in Example 4

[0075]

[0076]

Claims

1. A slurry for preparing 3D printed ceramic filters, characterized in that, The filter comprises 90-92 wt% ZrO2, 4.7-4.8 wt% MgO, 1.9-2.0 wt% HfO2, and 1.4-1.5 wt% SiO2; the slurry comprises the following components by weight: a photosensitive resin premix consisting of 5-15 parts monomer a, 3-9 parts monomer b, 2-6 parts monomer c, and 0.02-0.4 parts initiator; 0.7-2.7 parts dispersant; and 70-90 parts zirconium oxide mixture, wherein the zirconium oxide mixture is composed of zirconium oxide powder and magnesium oxide powder, and the content of magnesium oxide powder is 2-10 wt% of the zirconium oxide mixture. The monomers a and b are selected from two of the following: glycol diacrylate, tripropylene glycol diacrylate, hydroxyethyl acrylate, polyethylene glycol diacrylate, and dimethacrylate; the monomer c is selected from urethane dimethacrylate.

2. The mixed slurry according to claim 1, characterized in that, The monomer a is hexanediol diacrylate, monomer b is hydroxyethyl acrylate, and monomer c is dimethacrylate carbamate.

3. The mixed slurry according to claim 1, characterized in that, The slurry comprises the following components in parts by weight: 10-12 parts monomer a, 6-8 parts monomer b, 4-5 parts monomer c, 1.5-1.6 parts dispersant, 0.1-0.2 parts initiator, and 75-80 parts zirconium oxide mixture.

4. The mixed slurry according to claim 3, characterized in that, The slurry comprises the following components in parts by weight: 10 parts monomer a, 6 parts monomer b, 4 parts monomer c, 1.6 parts dispersant, 0.2 parts initiator, and 80 parts zirconium oxide mixture.

5. The mixed slurry according to claim 4, characterized in that, The zirconium oxide mixture contains 5 wt% magnesium oxide.

6. The mixed slurry according to claim 1, characterized in that, The dispersant is selected from one of BYK111, BYK163, and BYK180.

7. The mixed slurry according to claim 6, characterized in that, The dispersant is BYK111.

8. The mixed slurry according to claim 6, characterized in that, The initiator is selected from bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide and 2,4,6-trimethylbenzoyl-xylylphosphine oxide.

9. The mixed slurry according to claim 6, characterized in that, The initiator is selected from bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide.

10. The mixed slurry according to claim 6, characterized in that, The zirconium oxide mixture has a particle size of 325-800 mesh.

11. The mixed slurry according to claim 1, characterized in that, The mass ratio of monomer a, monomer b, and monomer c to the mass of the zirconium oxide mixture is 10-30:90-70; the mass ratio of the initiator to the mass of monomer a, monomer b, and monomer c is 1:500-1:

50.

12. The mixed slurry according to claim 11, characterized in that, The mass ratio of the initiator to the sum of the masses of monomers a, b, and c is 1:200-1:100; the mass ratio of the dispersant to the zirconium oxide mixture is 1:30-1:

80.

13. The mixed slurry according to claim 1, characterized in that, The mixed slurry also contains silicone-modified epoxy resin, which accounts for 3-10% of the mass of the photosensitive resin premix, and the solid content of the silicone-modified epoxy resin is 50±1%.

14. The mixed slurry according to any one of claims 1 to 13, characterized in that, The mixed slurry also contains a liquid sintering aid, which accounts for 0.5-1.5 wt% of the mass of the mixed slurry, and the liquid sintering aid is polyethylene glycol.

15. The mixed slurry according to claim 14, characterized in that, The mixed slurry also contains anti-settling wax, which accounts for 1.5-2.5 wt% of the mass of the mixed slurry.

16. A method for preparing a 3D-printed ceramic filter, characterized in that, The method of using the slurry for preparing 3D printed ceramic filters according to any one of claims 1-15 includes the following steps: (1) Preparation of mixed slurry: First, mix monomer a, monomer b, monomer c and initiator using a planetary ball mill for 20-30 min to obtain photosensitive resin premix; then add zirconium oxide mixture and dispersant, and continue mixing for 30-40 min to obtain mixed slurry; (2) Preparation of ceramic slurry: The mixed slurry is filtered through a vacuum filter and then placed in a vacuum pump for 10-20 minutes to obtain ceramic slurry; (3) 3D printing: Use 3D modeling software to build a 3D printing model of ceramic filter. Use the software provided by the printer to decompose the model into a series of slices with a thickness of 50-100μm. Input the data of the established 3D printing model into the DLP 3D printer and set the printing parameters: exposure power of 10-30mw / cm², first layer printing time of 10-20s, and material thickness of 50-150μm. Scan and solidify the ceramic slurry according to the above printing parameters. After printing, remove the ceramic filter from the forming table, rinse off the excess slurry, and obtain the ceramic filter preform. (4) Sintering: The ceramic filter blank obtained by printing is heated to 900-1200℃ at a heating rate of 1-2℃ / min and held for 0.5-2h. Then, it is heated to 1600-1700℃ at a heating rate of 0.5-2℃ / min and held for 1-3h. It is then naturally cooled to room temperature to obtain the 3D printed ceramic filter.

17. The method for preparing a 3D-printed ceramic filter according to claim 16, characterized in that, In step (1), silicone-modified epoxy resin, liquid sintering aid, and anti-settling wax are added to the photosensitive resin premix.

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