A porous material and a method for producing the same

Abstract

The application provides a kind of porous material and its preparation method, belongs to porous material technical field, including the following steps, the titanium powder with certain oxygen content, binder, plasticizer, pore-forming agent and solvent are mixed uniformly according to certain proportion to obtain slurry;The slurry is coated on the substrate by the way of doctor blade, and the titanium film green body is obtained after drying and stripping from the substrate;The titanium film green body is placed on the self-made sintering device, and the nanowire Ti6O porous film is prepared after debinding and sintering in the protective atmosphere.The application provides a kind of porous material and its preparation method, realizes the purpose of large-scale preparation of self-supporting porous material.

Description

Technical Field

[0001] This invention relates to the field of porous materials technology, specifically to a porous material and its preparation method. Background Technology

[0002] The research on novel inorganic electronic compound materials has attracted great attention due to their potential applications in transparent conductors, battery electrodes, electron emitters, and chemical synthesis catalysis. Electronic compound materials are special ionic crystal materials in which electrons act as anions. Unlike traditional metallic materials, their electrons are not randomly distributed but rather regionally. Ti-rich Ti-O compounds are essentially potential zero-dimensional electronic compound materials, where excess electrons are bound in atomic-sized lattice interstices or between cation layers, acting as anions. The stable chemical mechanism of electronic compounds lies in the multi-cavity and layered atomic filling caused by the Ti6O polyhedral unit structure, providing an ideal habitat for excess electrons. However, the reported methods for preparing Ti6O are currently limited. In 2019, Waseem Haider et al. published "Formation of nanotubes on commercially puretitanium at high potentials (=10V) and their electrochemical response" in Materials Research Express, and in 2020, Kiran A Nirmal et al. published "Resistive switching characteristics of electrochemically anodized substoichiometric Ti6O phase" in Journal of Nano-and Electronic Physics, respectively, nanotube-shaped Ti6O was prepared on small titanium sheets and titanium foils by electrochemical anodization. However, the electrochemical anodization method can only synthesize Ti6O on the outer surface of dense sheets, and the size is limited, which cannot meet the practical application requirements of electronic compounds.

[0003] Therefore, there is a need to provide a porous material and its preparation method to solve the problems of Ti6O materials prepared by electrochemical anodizing in the prior art being unable to support themselves independently and being difficult to manufacture on a large scale. Summary of the Invention

[0004] In view of this, the present invention provides a porous material and a method for preparing the same, thereby enabling the large-scale preparation of self-supporting nanowire-shaped Ti6O porous membranes.

[0005] To achieve the above objectives, the present invention provides a method for preparing a porous material, comprising the following steps: mixing titanium powder with a certain oxygen content, a binder, a plasticizer, a pore-forming agent, and a solvent in a certain proportion to obtain a slurry; coating the slurry onto a substrate by a scraping method, drying it, and then peeling it off from the substrate to obtain a titanium film green body; placing the titanium film green body on a self-made sintering apparatus, and degreasing and sintering it under a protective atmosphere to obtain a nanowire-like Ti6O porous membrane.

[0006] The technical solution provided by this invention involves the direct in-situ growth of a titanium film green body into a self-supporting nanowire-shaped porous Ti6O membrane. This technical solution is simple and easy to implement, saving production costs and enabling large-scale manufacturing. The self-made sintering apparatus provided by this invention is assembled from porous sintering plates with adjustable gaps and a surface-sprayed release agent. The release agent effectively prevents the nanowire-shaped Ti6O porous membrane from adhering to the sintering plate. The adjustable gaps are achieved through spacers between the sintering plates, avoiding excessive stress on the bottom layer membrane during large-scale, multi-layer stacking sintering, which increases the difficulty of removing degreasing volatiles and leads to degreasing residue. The porous sintering plate facilitates the removal of volatiles during degreasing and can also adsorb some volatile impurities to prevent deposition on the surface of the Ti6O porous membrane, thus ensuring its quality.

[0007] Optionally, the self-made sintering device includes a porous sintering plate and gaskets. A release agent is sprayed onto the porous sintering plate. The titanium film green blank is placed on the porous sintering plate. Multiple porous sintering plates are stacked sequentially through the gaskets, which are placed at the four corners of the porous sintering plate to adjust the gap between the porous sintering plates.

[0008] Optionally, the ratio of the titanium powder, binder, plasticizer, pore-forming agent and solvent is (50~80wt%):(1~6wt%):(0.5~4wt%):(2.5~8wt%):(14~36wt%), and the sum of the mass percentages of each component is 100%.

[0009] Optionally, the titanium powder has an oxygen content of 0.1~1.0wt% and an average particle size of ≤100μm; the pore-forming agent has an average particle size of 5~20μm.

[0010] Optionally, the sintering conditions are 800~1200℃ for 1~3 hours; the degreasing includes a first stage degreasing condition of 250~350℃ for 0.5~1 hours and a second stage degreasing condition of 450~550℃ for 1~3 hours; the drying includes a first stage drying condition of 35~55℃ and a second stage drying condition of 75~100℃.

[0011] Optionally, the height of the scraper during the coating process is 50~2500μm.

[0012] Optionally, the substrate may include a silicone oil-treated plastic film, a glass plate, a ceramic plate, a granite plate, or a steel plate.

[0013] Optionally, the adhesive is one or more of polyvinyl butyral, polyvinylpyrrolidone, polyacrylic acid, and polyacrylamide; the plasticizer is one or more of dibutyl phthalate, glycerol, and dioctyl phthalate; the pore-forming agent is one or more of polymethyl methacrylate and polystyrene; and the solvent is one or more of methanol, ethanol, ethylene glycol, isopropanol, and butanol.

[0014] Optionally, the process of mixing uniformly to obtain a slurry includes heating and stirring the binder to dissolve it in the solvent to form a binder solution, cooling and allowing it to stand for aging to remove bubbles; slowly adding the plasticizer to the binder solution while stirring; after fully mixing uniformly, slowly adding the pore-forming agent while stirring; after fully mixing uniformly, slowly adding the titanium powder while stirring, and fully mixing uniformly to form a slurry.

[0015] The proportions of the components selected in the technical solution provided by this invention result in a smooth, flat, defect-free Ti6O porous membrane with uniform pore distribution. Furthermore, the porosity and pore size can be customized by adjusting the titanium powder particle size, pore-forming particle size, and sintering process. The binder, plasticizer, pore-forming agent, and solvent selected in this invention leave virtually no residue during heat treatment, posing no harm to the application of the Ti6O porous membrane in transparent conductors, battery electrodes, electron emitters, and chemical synthesis catalysis. The binder, plasticizer, pore-forming agent, and solvent selected in this invention have significant effects on improving the dispersion stability of subsequently added titanium powder and on constructing the pore structure of the Ti6O porous membrane.

[0016] The sintering process provided by this invention enables the diffusion and bonding of oxygen-containing titanium powder to obtain a sintered porous body with a certain strength. During the initial degreasing process, the binder, plasticizer, pore-forming agent, and residual solvent decompose rapidly. During the subsequent degreasing process, the high temperature ensures that all organic substances are fully removed and quickly carried out of the furnace by the continuously flowing protective atmosphere. The initial drying temperature is relatively low to prevent the solvent evaporation rate on the surface of the blank from being much greater than the diffusion rate of the solvent in the blank, which would result in an excessively thick drying layer on the upper surface and hinder the continuous diffusion of the solvent inside the blank. At the same time, the initial temperature is not too low, which would cause the blank to dry too slowly and the heavier titanium powder particles in the slurry to settle. The subsequent temperature ensures that the titanium film blank is dried and cured, making it easy to peel off from the substrate surface.

[0017] The substrate selected in the technical solution provided by this invention facilitates the peeling of the dried titanium film preform from the substrate surface. The slurry is evenly coated on the substrate by a scraper, and the thickness of the titanium film preform can be controlled by adjusting the scraper height. At the same time, the scraper coating ensures that the surface of the titanium film preform is flat and smooth with uniform thickness, which facilitates the controllable preparation of titanium film preforms of different thicknesses.

[0018] The technical solution provided by this invention selects a plasticizer in the cross-linked colloidal network structure of the binder solution to soften the binder polymer chain and increase the flexibility of the green body; the pore-forming agent is uniformly dispersed in the binder network, and together they play a steric hindrance role in the uniform dispersion of titanium powder, thereby forming a uniform and stable slurry.

[0019] To achieve the above objectives, the present invention also provides a method for preparing nanowire-shaped Ti6O porous membranes using a porous material preparation method.

[0020] The rigid porous network structure formed by the nanowire-shaped Ti6O porous membrane provided by this invention gives the Ti6O membrane more active sites, making it a promising material for electronic compounds in transparent conductors, battery electrodes, electron emitters, and chemical synthesis catalysis.

[0021] The above-described technical solution of the present invention has at least the following beneficial effects:

[0022] This invention provides a porous material and its preparation method, which directly grows a self-supporting nanowire-shaped Ti6O porous membrane in situ from a titanium membrane green body. The process is simple and easy to implement, which not only saves production costs but also enables large-scale manufacturing. The rigid porous network structure formed gives the Ti6O membrane more active sites, making it a promising material for electronic compounds in transparent conductors, battery electrodes, electron emitters, and chemical synthesis catalysis. Attached Figure Description

[0023] Figure 1 This is a flowchart illustrating the fabrication process of the nanowire-shaped Ti6O porous membrane in this embodiment of the invention.

[0024] Figure 2 This is an assembly diagram of the titanium film green body and the self-made sintering device in an embodiment of the present invention;

[0025] Figure 3 This is an X-ray diffraction pattern of the nanowire-shaped Ti6O porous membrane in Example 5 of the present invention;

[0026] Figure 4 This is a scanning electron microscope image of the nanowire-shaped Ti6O porous membrane in Example 5 of the present invention;

[0027] Figure 5 This is a scanning electron microscope (SEM) image of the cross-section of the nanowire-shaped Ti6O porous membrane in Example 5 of the present invention.

[0028] Appendix Figure 2 In the middle: 1. Porous firing plate; 2. Titanium film green blank; 3. Gasket. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the following will be described in conjunction with the accompanying drawings of the embodiments of the present invention. Figure 1-5 The technical solutions of the embodiments of the present invention will be clearly and completely described herein. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art based on the described embodiments of the present invention are within the scope of protection of the present invention.

[0030] Example 1

[0031] Titanium powder with an average particle size of 61 μm and an oxygen content of 0.34 wt% was prepared in a ratio of 55 wt%:2 wt%:3 wt%:5 wt%:35 wt%, along with polyvinylpyrrolidone (PVP), dibutyl phthalate (DBP), polymethyl methacrylate (PMMA) with an average particle size of 10 μm, and ethanol. PPVP was heated and stirred to dissolve in ethanol to form a binder solution, which was then cooled and allowed to stand to remove bubbles. DBP was slowly added to the binder solution while stirring. After thorough mixing, PMMA was slowly added while stirring. Titanium powder was then slowly added while stirring, and the mixture was thoroughly mixed to form a slurry. The resulting slurry was coated onto a silicone-treated plastic film using a doctor blade with a height of 400 μm. After segmental drying at 40°C and 80°C, the film was peeled off from the substrate to obtain a titanium film preform. A titanium film preform was placed on a self-made sintering apparatus and sintered at 300℃ for 1 hour under an argon atmosphere, followed by a further holding at 500℃ for 1 hour, and finally at 900℃ for 1 hour to obtain a self-supporting nanowire-shaped Ti6O porous membrane, i.e., sample 1. The obtained porous material has a porosity of 71%, a pore size of 18 μm, and an air permeability of 1542 m. 3 / (h·kPa·m 2 ).

[0032] The technical solution provided by this invention involves the direct in-situ growth of a titanium film green body into a self-supporting nanowire-shaped porous Ti6O membrane. This technical solution is simple and easy to implement, saving production costs and enabling large-scale manufacturing. The self-made sintering apparatus provided by this invention is assembled from porous sintering plates with adjustable gaps and a surface-sprayed release agent. The release agent effectively prevents the nanowire-shaped Ti6O porous membrane from adhering to the sintering plate. The adjustable gaps are achieved through spacers between the sintering plates, avoiding excessive stress on the bottom layer membrane during large-scale, multi-layer stacking sintering, which increases the difficulty of removing degreasing volatiles and leads to degreasing residue. The porous sintering plate facilitates the removal of volatiles during degreasing and can also adsorb some volatile impurities to prevent deposition on the surface of the Ti6O porous membrane, thus ensuring its quality.

[0033] Example 2

[0034] The only difference from Example 1 is that the sintering temperature was 1000℃ for 3 hours to obtain a self-supporting nanowire-shaped Ti6O porous membrane, i.e., Sample 2. The obtained porous material has a porosity of 63%, a pore size of 19 μm, and an air permeability of 1352 μm. 3 / (h·kPa·m 2 ).

[0035] Example 3

[0036] The only difference from Example 1 is that the sintering temperature was 1100℃ for 2 hours to obtain a self-supporting nanowire-shaped Ti6O porous membrane, i.e., Sample 3. The obtained porous material has a porosity of 59%, a pore size of 19 μm, and an air permeability of 1054 μm. 3 / (h·kPa·m 2 ).

[0037] Example 4

[0038] Titanium powder with an average particle size of 38 μm and an oxygen content of 0.52 wt% was prepared in a ratio of 55 wt%:2 wt%:3 wt%:5 wt%:35 wt%, along with polyvinylpyrrolidone (PVP), dibutyl phthalate (DBP), polymethyl methacrylate (PMMA) with an average particle size of 10 μm, and ethanol. PPVP was heated and stirred to dissolve in ethanol to form a binder solution, which was then cooled and allowed to stand to remove bubbles. DBP was slowly added to the binder solution while stirring. After thorough mixing, PMMA was slowly added while stirring. Titanium powder was then slowly added while stirring, and the mixture was thoroughly mixed to form a slurry. The resulting slurry was coated onto a silicone-treated plastic film using a doctor blade with a height of 400 μm. After segmental drying at 40℃ and 80℃, the film was peeled off from the substrate to obtain a titanium film preform. The titanium film preform was placed on a self-made sintering apparatus and held at 300℃ for 1 hour under an argon atmosphere, followed by holding at 500℃ for 2 hours, and then at 1000℃ for 2 hours to obtain a self-supporting nanowire-shaped Ti6O porous membrane, i.e., sample 4. The obtained porous material has a porosity of 58%, a pore size of 18 μm, and an air permeability of 1209 μm. 3 / (h·kPa·m 2 ).

[0039] Example 5

[0040] The only difference from Example 4 is that titanium powder, polyvinylpyrrolidone, dibutyl phthalate, polymethyl methacrylate, and ethanol were prepared in a ratio of 65wt%:2wt%:3wt%:5wt%:25wt%, resulting in Sample 5. The resulting porous material had a porosity of 52%, a pore size of 18μm, and an air permeability of 909 μm. 3 / (h·kPa·m 2 X-ray diffraction tests were performed on sample 5. Figure 3 Scanning electron microscopy (SEM) tests were performed on the surface and cross-section of sample 5, respectively. Figure 4 , Figure 5 .

[0041] Example 6

[0042] The only difference from Example 4 is that titanium powder, polyvinylpyrrolidone, dibutyl phthalate, polymethyl methacrylate, and ethanol were prepared in a ratio of 75wt%:2wt%:3wt%:5wt%:15wt%, resulting in Sample 6. The prepared porous material had a porosity of 46%, a pore size of 17μm, and an air permeability of 788µm. 3 / (h·kPa·m 2 ).

[0043] Example 7

[0044] The only difference from Example 5 is that the average particle size of polymethyl methacrylate is 5 μm. Sample 7 was obtained. The resulting porous material has a porosity of 51%, a pore size of 13 μm, and an air permeability of 552 μm. 3 / (h·kPa·m 2 ).

[0045] Example 8

[0046] The only difference from Example 5 is that the average particle size of polymethyl methacrylate is 20 μm. Sample 8 was obtained. The resulting porous material has a porosity of 52%, a pore size of 29 μm, and an air permeability of 1817 m. 3 / (h·kPa·m 2 ).

[0047] Example 9

[0048] The only differences from Example 5 are that the average particle size of the titanium powder is 12 μm, the oxygen content is 0.77 wt%, and the sintering temperature is 900℃. Sample 9 was obtained. The resulting porous material has a porosity of 61%, a pore size of 9 μm, and an air permeability of 361 μm. 3 / (h·kPa·m 2 ).

[0049] Table 1. Relevant variables of components 1-9 in Examples and corresponding performance of samples 1-9.

[0050] Example Oxygen content of titanium powder (wt%) Average particle size of titanium powder (μm) Average particle size of pore-forming agent (μm) Slurry ratio (wt%) Sintering temperature (°C) Porosity (%) Aperture (μm) <![CDATA[Permeability coefficient m 3 / (h·kPa·m 2 )]]> 1 0.34 61 10 55:2:3:5:35 900 71 18 1542 2 0.34 61 10 55:2:3:5:35 1000 63 19 1352 3 0.34 61 10 55:2:3:5:35 1100 59 19 1054 4 0.52 38 10 55:2:3:5:35 1000 58 18 1209 5 0.52 38 10 65:2:3:5:25 1000 52 18 909 6 0.52 38 10 75:2:3:5:15 1000 46 17 788 7 0.52 38 5 65:2:3:5:25 1000 51 13 552 8 0.52 38 20 65:2:3:5:25 1000 52 29 1817 9 0.77 12 10 65:2:3:5:25 900 61 9 361

[0051] As shown in Table 1, Examples 1, 2, and 3 differ only in sintering temperature, which is 900℃, 1000℃, and 1100℃, respectively. The porosities of the prepared nanowire-shaped Ti6O porous membranes are 71%, 63%, and 59%, respectively; the pore sizes are 18μm, 19μm, and 19μm, respectively; and the air permeability coefficients are 1542m. 3 / (h·kPa·m 2 ), 1352m 3 / (h·kPa·m 2 ), 1054m 3 / (h·kPa·m 2 As can be seen, with the increase of sintering temperature, the pore size of the prepared porous material is close, while the porosity and air permeability decrease.

[0052] As shown in Table 1, Examples 4, 5, and 6 differed only in the slurry ratio, with titanium powder to solvent ratios of 55:35, 65:25, and 75:15, respectively. The porosities of the prepared nanowire-shaped Ti6O porous membranes were 58%, 52%, and 46%, respectively, with pore sizes of 18 μm, 18 μm, and 17 μm, and air permeability coefficients of 1209 m. 3 / (h·kPa·m2 ), 909m 3 / (h·kPa·m 2 ), 788m 3 / (h·kPa·m 2 As can be seen, with the increase of titanium powder in the slurry ratio, the pore size of the prepared porous material is close, while the porosity and air permeability decrease.

[0053] As shown in Table 1, Examples 5, 7, and 8 differ only in the average particle size of the pore-forming agent, which are 10 μm, 5 μm, and 20 μm, respectively. The porosities of the prepared nanowire-shaped Ti6O porous membranes are 52%, 51%, and 52%, respectively; the pore sizes are 18 μm, 13 μm, and 29 μm, respectively; and the air permeability coefficients are 1209 m. 3 / (h·kPa·m 2 ), 552m 3 / (h·kPa·m 2 ), 1817m 3 / (h·kPa·m 2 As can be seen, with the increase of the particle size of the pore-forming agent, the porosity of the prepared porous material is close to that of the pore size and the air permeability coefficient increases.

[0054] In summary, under certain conditions, the porosity and permeability of nanowire-shaped Ti6O porous membranes are negatively correlated with sintering temperature and the proportion of titanium powder in the slurry; while the pore size and permeability are positively correlated with the average particle size of the pore-forming agent. The porosity and pore size of porous materials can be customized by adjusting the titanium powder particle size, the proportion of titanium powder in the slurry, the particle size of the pore-forming agent, and the sintering process.

[0055] Depend on Figure 3 It can be seen that the phase prepared by the technical solution provided by the present invention corresponds to the characteristic peak of Ti6O, and it can be seen that the technical solution provided by the present invention prepares a Ti6O film.

[0056] Depend on Figure 4 , Figure 5 The figure shows that the Ti6O film prepared by the technical solution provided by the present invention was scanned by electron microscopy. Parts A and B in the figure are local electron microscopy scans magnified to different degrees. As can be seen from the figure, the Ti6O film prepared by the technical solution provided by the present invention is a nanowire Ti6O porous film.

[0057] The above are preferred embodiments of the present invention. It should be noted that, for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing a porous material, characterized in that, The process includes the following steps: titanium powder with a certain oxygen content, binder, plasticizer, pore-forming agent, and solvent are mixed uniformly in a certain proportion to obtain a slurry; the slurry is coated onto a substrate by a scraping method, and after drying, it is peeled off from the substrate to obtain a titanium film green body; the titanium film green body is placed on a self-made sintering apparatus, and after degreasing and sintering under a protective atmosphere, a nanowire-like Ti6O porous membrane is obtained; the self-made sintering apparatus includes a porous sintering plate and gaskets; a release agent is sprayed onto the porous sintering plate; the titanium film green body is placed on the porous sintering plate; multiple porous sintering plates are stacked sequentially through the gaskets, which are placed at the four corners of the porous sintering plates to adjust the gap between the porous sintering plates; the titanium powder has an oxygen content of 0.1~1.0wt% and an average particle size ≤100μm.

2. The method for preparing porous materials according to claim 1, characterized in that, The ratio of titanium powder, binder, plasticizer, pore-forming agent and solvent is (50 ~ 80 wt%): (1 ~ 6 wt%): (0.5 ~ 4 wt%): (2.5 ~ 8 wt%): (14 ~ 36 wt%), and the sum of the mass percentages of each component is 100%.

3. The method for preparing porous materials according to claim 2, characterized in that, The average particle size of the pore-forming agent is 5~20μm.

4. The method for preparing porous materials according to claim 1, characterized in that, The sintering conditions are 800-1200℃ for 1-3 hours; the degreasing includes a first stage of degreasing at 250-350℃ for 0.5-1 hours and a second stage of degreasing at 450-550℃ for 1-3 hours; the drying includes a first stage of drying at 35-55℃ and a second stage of drying at 75-100℃.

5. The method for preparing porous materials according to claim 1, characterized in that, The height of the scraper during the coating process is 50~2500μm.

6. The method for preparing porous materials according to claim 1, characterized in that, The substrate includes silicone oil-treated plastic films, glass plates, ceramic plates, granite plates, and steel plates.

7. The method for preparing porous materials according to claim 1, characterized in that, The adhesive is one or more of polyvinyl butyral, polyvinylpyrrolidone, polyacrylic acid, and polyacrylamide; the plasticizer is one or more of dibutyl phthalate, glycerol, and dioctyl phthalate; the pore-forming agent is one or more of polymethyl methacrylate and polystyrene; and the solvent is one or more of methanol, ethanol, ethylene glycol, isopropanol, and butanol.

8. The method for preparing porous materials according to claim 1, characterized in that, The process of mixing the binder to form a slurry involves heating and stirring the binder in the solvent to form a binder solution, cooling and allowing it to stand to defoam; slowly adding the plasticizer to the binder solution while stirring; after thorough mixing, slowly adding the pore-forming agent while stirring; after thorough mixing, slowly adding the titanium powder while stirring, and then thoroughly mixing to form the slurry.

9. A nanowire-shaped Ti6O porous membrane prepared by a method for preparing porous materials according to any one of claims 1 to 8.

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