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CN-122006516-A - Silicon carbide composite ceramic membrane with gradient pore diameter structure

CN122006516ACN 122006516 ACN122006516 ACN 122006516ACN-122006516-A

Abstract

The application belongs to the field of silicon carbide ceramic membranes, and particularly provides a silicon carbide composite ceramic membrane with a gradient pore diameter structure, which comprises a supporting layer, a transition layer and a separation layer from inside to outside in sequence; the transition layer and the separation layer are sintered after being treated by coating liquid, and the preparation method of the coating liquid comprises the following steps of S01, taking germanium-containing optical fiber waste, grinding, mixing with carbon powder and ferric oxide powder, continuing ball milling to obtain mixed micro powder, S02, adding silicon carbide micro powder and the mixed micro powder into dispersion liquid, stirring, then adding a silane coupling agent, continuing stirring, standing and defoaming to obtain the composite micro powder. The coating liquid prepared by the application can reduce the sintering temperature of the silicon carbide composite ceramic membrane and reduce the process cost.

Inventors

  • ZHANG YUNFEI
  • SHEN HONGMEI
  • QI YUANFENG
  • HE JINPING
  • GAO QI

Assignees

  • 浙江坚膜科技有限公司

Dates

Publication Date
20260512
Application Date
20260413

Claims (10)

  1. 1. The silicon carbide composite ceramic membrane with the gradient pore diameter structure is characterized by comprising a supporting layer, a transition layer and a separation layer which are sequentially arranged from inside to outside, wherein the transition layer and the separation layer are formed by sintering after being treated by coating liquid; The preparation method of the coating liquid comprises the following steps: s01, grinding germanium-containing optical fiber waste, then mixing with carbon powder and ferric oxide powder, and continuing ball milling to obtain mixed micro powder; S02, adding the silicon carbide micro powder and the mixed micro powder into the dispersion liquid, stirring, then adding the silane coupling agent, continuously stirring, standing and defoaming to obtain the silicon carbide micro powder.
  2. 2. The silicon carbide composite ceramic membrane with the gradient pore diameter structure according to claim 1, wherein In the step S01, the germanium-containing optical fiber waste comprises the following components, by mass, 96.2% -98.1% of SiO 2 , 0.9% -2.2% of Na 2 O, 0.5% -1.5% of GeO 2 , 0.03% -0.04% of K 2 O, 0.01% -0.02% of SnO 2 and less than 0.02% of In and Ti impurities.
  3. 3. The silicon carbide composite ceramic membrane with the gradient pore diameter structure according to claim 1, wherein in the step S01, the mass ratio of the germanium-containing optical fiber waste to the carbon powder is (5-5.25) (3.1-3.3), and the ferric oxide powder is added according to the adding amount of 3% -3.5% of the total mass ratio of the germanium-containing optical fiber waste to the carbon powder.
  4. 4. The silicon carbide composite ceramic membrane with the gradient pore diameter structure of claim 1, wherein in the step S02, the preparation step of the dispersion liquid comprises the steps of mixing methylcellulose and polyacrylic acid, adding water for dispersion, and stirring at constant temperature for dissolution.
  5. 5. The silicon carbide composite ceramic membrane with the gradient pore diameter structure according to claim 4, wherein the mass-volume ratio of methyl cellulose, polyacrylic acid and water is (0.3-0.5) g (0.5-0.6) g (75-80) mL, and the constant-temperature stirring temperature is set to be 60-80 ℃.
  6. 6. The silicon carbide composite ceramic membrane with a gradient pore size structure according to claim 1, wherein in the step S02, the silane coupling agent is KH550.
  7. 7. The silicon carbide composite ceramic membrane with the gradient pore diameter structure of claim 1, wherein the transition layer uses silicon carbide micro powder with the average particle size of 2-2.8 microns, and the separation layer uses silicon carbide micro powder with the average particle size of 0.8-1.3 microns.
  8. 8. The silicon carbide composite ceramic membrane with the gradient pore diameter structure according to claim 1, wherein the preparation steps comprise the following steps: M01 collecting porous silicon carbide ceramic support, washing with water, and oven drying; and M02, placing the support body in coating liquid, soaking, lifting and treating, and then sintering to respectively prepare the ceramic membrane transition layer and the separation layer.
  9. 9. The silicon carbide composite ceramic membrane with the gradient pore diameter structure according to claim 8, wherein in the step M02, the support is immersed into the coating liquid at a speed of 0.5-1.5cm/s, the immersion time is kept for 30-90 seconds, the liquid level is lifted out at a constant speed of 1-3cm/s, and the support is dried for standby.
  10. 10. The silicon carbide composite ceramic membrane having a gradient pore size structure according to claim 8, wherein in the step M02, the sintering is performed by heating to 1150-1220 ℃ at 0.5-1.3 ℃ per min, maintaining the temperature for 1-2 hours, and then continuing to heat to 1385-1420 ℃ at 3.2-3.5 ℃ and maintaining the temperature for 2-2.5 hours.

Description

Silicon carbide composite ceramic membrane with gradient pore diameter structure Technical Field The application belongs to the technical field of silicon carbide ceramic membranes, and particularly relates to a silicon carbide composite ceramic membrane with a gradient pore diameter structure. Background The silicon carbide ceramic membrane has wide application prospect in the fields of high-temperature filtration, catalytic carriers and separation because of excellent high-temperature stability, chemical inertness and mechanical strength. The traditional silicon carbide composite ceramic membrane generally comprises a macroporous supporting layer, an intermediate transition layer and a surface microporous separating layer, wherein the transition layer and the separating layer are manufactured by high-temperature sintering after being treated by a coating liquid dipping or spraying process. Because of the high covalent bonding energy of carbon and silicon in silicon carbide, ceramic membrane sintering is usually carried out at a high temperature of more than 1800 ℃, which results in high energy consumption, severe equipment requirements and greatly increased production cost. At present, research is attempted to reduce the sintering temperature of the silicon carbide ceramic membrane by adding sintering aids, but the common aids such as pure substances of aluminum oxide, magnesium oxide, yttrium oxide and the like have cost problems, and the organic sintering aids have the risk of introducing organic matters, so that the pore forming and membrane forming quality of the silicon carbide can be reduced, and the effects of the sintering aids are difficult to meet the use requirements of the silicon carbide ceramic membrane. Therefore, the development of a preparation method of the silicon carbide composite ceramic membrane capable of reducing the sintering temperature and reducing the industrial cost has important industrial significance. Disclosure of Invention In order to further reduce the sintering temperature of the silicon carbide ceramic membrane and reduce the production cost, the application provides the silicon carbide composite ceramic membrane with the gradient pore diameter structure. The silicon carbide composite ceramic membrane with the gradient pore diameter structure is formed by sintering a support layer, a transition layer and a separation layer which are sequentially arranged from inside to outside after being treated by coating liquid; The preparation method of the coating liquid comprises the following steps: s01, grinding germanium-containing optical fiber waste, then mixing with carbon powder and ferric oxide powder, and continuing ball milling to obtain mixed micro powder; S02, adding the silicon carbide micro powder and the mixed micro powder into the dispersion liquid, stirring, then adding the silane coupling agent, continuously stirring, standing and defoaming to obtain the silicon carbide micro powder; the transition layer uses silicon carbide micro powder with the average grain diameter of 2-2.8 microns; The separation layer uses silicon carbide micropowder with average particle diameter of 0.8-1.3 microns; In the step S01, the germanium-containing optical fiber waste comprises 96.2-98.1% of SiO 2, 0.9-2.2% of Na 2 O, 0.5-1.5% of GeO 2, 0.03-0.04% of K 2 O, 0.01-0.02% of SnO 2 and less than 0.02% of In and Ti impurities. By adopting the technical scheme, the germanium-containing optical fiber waste is mixed with carbon powder and ferric oxide powder, and main phase silicon dioxide components in the waste are subjected to carbothermic reduction in the sintering process to obtain silicon carbide, the supplementary silicon carbide is introduced, so that mass transfer and densification among silicon carbide particles can be promoted, the consolidation forming process of a ceramic film is promoted, silicon atoms in silicon carbide crystal lattices are replaced by a near-diameter structure in the silicon carbide recrystallization sintering process, the lattice distortion is induced, the phase transition and gas phase migration of the silicon carbide are promoted, and the silicon carbide recrystallization can be carried out at a lower temperature. In the step S01, the mass ratio of the germanium-containing optical fiber waste to the carbon powder is (5-5.25) (3.1-3.3), and the ferric oxide powder is added according to the adding amount of the germanium-containing optical fiber waste and the carbon powder accounting for 3% -3.5% of the total mass ratio. Further, in the step S02, the preparation method of the dispersion liquid comprises the steps of mixing methylcellulose and polyacrylic acid, adding water for dispersion, stirring at constant temperature for dissolution to obtain the final product; the mass volume ratio of the methyl cellulose, the polyacrylic acid and the water is (0.3-0.5) g (0.5-0.6) g (75-80) mL, and the constant temperature stirring temperature is set to be 60-80 ℃;