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CN-121974722-A - Silicon carbide porous ceramic for in-situ induction of low-temperature eutectic and preparation method thereof

CN121974722ACN 121974722 ACN121974722 ACN 121974722ACN-121974722-A

Abstract

The invention relates to the technical field of silicon carbide ceramics, in particular to silicon carbide porous ceramics for in-situ induction of low-temperature eutectic and a preparation method thereof; the invention adopts pregelatinized starch as an adhesive, and the thermal decomposition behavior of the pregelatinized starch and the chemical reactivity of the glass powder and the calcium carbonate form synergy in the process, so that the full-flow seamless connection from room temperature to sintering temperature is realized, the sintering temperature is greatly reduced, the glue discharging step is omitted, and the silicon carbide porous ceramic product with good performance and few defects is obtained.

Inventors

  • GE YUNJIE
  • ZHOU DI
  • LIU YUXIAN

Assignees

  • 常州赛璞睿生科技有限公司

Dates

Publication Date
20260505
Application Date
20260126

Claims (9)

  1. 1. The silicon carbide porous ceramic for in-situ induction of low-temperature eutectic is characterized by comprising the following materials in percentage by mass: 50-80% of silicon carbide, 10-40% of a collaborative sintering system, 0.02-0.5% of a dispersing agent, 0.5-2% of a plasticizer and 5-20% of water; Wherein the synergistic sintering system comprises the following 100 percent of pregelatinized starch 40-70 percent, silicate mineral material 5-20 percent, alumina 5-20 percent, calcium carbonate 5-20 percent, glass powder 5-30 percent and rare earth oxide 0.1-5 percent.
  2. 2. The silicon carbide porous ceramic of the in-situ induced low-temperature eutectic according to claim 1, which is characterized by comprising, by mass, 100% of materials, 60% -75% of silicon carbide, 15% -25% of a co-sintering system, 0.04% -0.2% of a dispersing agent, 0.8% -1.5% of a plasticizer and 5% -20% of water; Wherein the synergistic sintering system comprises the following 100 percent of pregelatinized starch 55 to 69.9 percent, silicate mineral material 6to 10 percent, alumina 8 to 12 percent, calcium carbonate 9 to 15 percent, glass powder 7 to 15 percent and rare earth oxide 0.1 to 0.5 percent.
  3. 3. The in situ induced low temperature co-crystal silicon carbide porous ceramic according to claim 2, wherein the molar ratio of carbon element in the pregelatinized starch to calcium element in the calcium carbonate is 15-28:1.
  4. 4. A silicon carbide porous ceramic according to claim 3, wherein said silicate mineral material is selected from one or more of bentonite, montmorillonite, illite, kaolinite, halloysite, chlorite; The rare earth oxide is selected from one or more of lanthanum oxide, cerium oxide and yttrium oxide; the glass powder is selected from one of borosilicate glass powder, soda-lime silicate glass powder, quartz glass powder and aluminosilicate glass powder.
  5. 5. The in situ induced low temperature co-crystal silicon carbide porous ceramic according to claim 4, wherein said silicate mineral material is selected from one or more of bentonite, montmorillonite; the rare earth oxide is selected from yttrium oxide; The glass powder is selected from borosilicate glass powder, wherein the borosilicate glass powder comprises the following components in percentage by mass of 100 percent of B 2 O 3 13%-15%、Na 2 O 3%-5%、Al 2 O 3 to 3 percent and the balance of SiO 2 .
  6. 6. The silicon carbide porous ceramic of claim 3, wherein the silicon carbide powder has an average particle size of less than 200 microns, the silicate mineral material has a particle size in the range of 1 micron to 10 microns, the calcium carbonate has a particle size in the range of 1 micron to 5 microns, the glass frit has a particle size in the range of 5 microns to 50 microns, the rare earth oxide has a particle size in the range of 0.5 microns to 3 microns, and the alumina has a particle size in the range of 0.5 microns to 3 microns.
  7. 7. A silicon carbide porous ceramic according to any of claims 1 to 6, wherein said dispersing agent is selected from one or more of sodium polyacrylate, sodium hexametaphosphate, polycarboxylic acid anionic dispersing agents, polycarboxylates; The plasticizer is one or more selected from glycerol, liquid paraffin and polyethylene glycol.
  8. 8. The method for preparing a silicon carbide porous ceramic inducing low temperature co-crystals in situ according to any one of claims 1 to 7, comprising the steps of: S1, uniformly mixing silicon carbide, a collaborative sintering system, a dispersing agent and a plasticizer dry material according to a proportion, and then adding water to uniformly disperse to form a wet material; s2, extruding or pressing the wet material to form a blank; And S3, sintering the green body at the temperature lower than 1600 ℃ in one step to obtain the silicon carbide porous ceramic with the in-situ induced low-temperature eutectic.
  9. 9. The method for preparing the silicon carbide porous ceramic with the in-situ induced low-temperature eutectic according to claim 8, wherein the temperature rise rate of the one-step sintering is 1 ℃ to 10 ℃ per minute, the sintering temperature is 1100 ℃ to 1400 ℃, and the sintering heat preservation time is 1 hour to 5 hours.

Description

Silicon carbide porous ceramic for in-situ induction of low-temperature eutectic and preparation method thereof Technical Field The invention relates to the technical field of silicon carbide ceramics, in particular to silicon carbide porous ceramics capable of inducing low-temperature eutectic in situ and a preparation method thereof. Background In the field of porous silicon carbide ceramic technology, sintering is a critical process that melts, diffuses, coats, bonds and densifies the powder by heating to achieve the desired mechanical strength, hardness and other physical properties. However, conventional sintering processes typically require extremely high temperatures (typically above 1600 ℃) which results in significant energy consumption, high production costs. In the current silicon carbide ceramic production process, in the green body forming stage, a certain amount of binder is required to be added in order to endow powder with good dry pressing, extrusion or casting forming performances. The most widely used at present are cellulose ether organic polymer binders such as hydroxypropyl methylcellulose (HPMC) and sodium carboxymethylcellulose (CMC). The adhesive has excellent water retention and film forming property, and can effectively improve the initial strength and plasticity of the blank. HPMC and CMC, among others, are high molecular weight polymers that require a slow and time-consuming "bleed-out" process before sintering. If the glue discharging rate is controlled improperly, the gas generated by the decomposition of the organic matters can escape rapidly in the blank, so that the blank is very easy to generate defects such as cracks, bubbles, holes and the like, and the yield and the performance consistency of the product are seriously reduced. The total production time is prolonged, the extra energy consumption is increased, and the utilization efficiency of the kiln is reduced. Disclosure of Invention The invention provides a silicon carbide porous ceramic with in-situ induced low-temperature eutectic and a preparation method thereof, which aim to solve the technical problems of high temperature, high energy consumption, long production period and more defects of a silicon carbide porous ceramic product in the traditional sintering process. The invention adopts pregelatinized starch as an adhesive, and the thermal decomposition behavior and the chemical reactivity of glass powder and calcium carbonate are cooperated in the process, so that the full-flow seamless connection from room temperature to sintering temperature is realized, the sintering temperature is greatly reduced, the glue discharging step is omitted, and the silicon carbide porous ceramic product with good performance and few defects is finally obtained. In order to achieve the above purpose, the invention is realized by the following technical scheme: the silicon carbide porous ceramic for in-situ induction of low-temperature eutectic comprises the following materials in percentage by mass: 50-80% of silicon carbide, 10-40% of a collaborative sintering system, 0.02-0.5% of a dispersing agent, 0.5-2% of a plasticizer and 5-20% of water; Wherein the synergistic sintering system comprises the following 100 percent of pregelatinized starch 40-70 percent, silicate mineral material 5-20 percent, alumina 5-20 percent, calcium carbonate 5-20 percent, glass powder 5-30 percent and rare earth oxide 0.1-5 percent. Preferably, the composite material is formed by mixing and sintering materials with the mass percentage of 60-75% of silicon carbide, 15-25% of a collaborative sintering system, 0.04-0.2% of a dispersing agent, 0.8-1.5% of a plasticizer and 5-20% of water; Wherein the synergistic sintering system comprises the following 100 percent of pregelatinized starch 55 to 69.9 percent, silicate mineral material 6to 10 percent, alumina 8 to 12 percent, calcium carbonate 9 to 15 percent, glass powder 7 to 15 percent and rare earth oxide 0.1 to 0.5 percent. Further, the molar ratio of the carbon element in the pregelatinized starch to the calcium element in the calcium carbonate is 15-28:1. The ratio of carbon element to calcium element in the formula can ensure enough reducing atmosphere to effectively reduce the decomposition temperature of calcium carbonate, and meanwhile, excessive residual carbon is not generated, namely, the carbon source is just enough to reduce and promote the decomposition, and the liquid phase is just enough to wrap and promote the densification. Preferably, the molar ratio of carbon element in the pregelatinized starch to calcium element in the calcium carbonate is 20-25:1. Further, the silicate mineral material is selected from one or more of bentonite, montmorillonite, illite, kaolinite, halloysite and chlorite; The rare earth oxide is selected from one or more of lanthanum oxide, cerium oxide and yttrium oxide; the glass powder is selected from one of borosilicate glass powder, soda-lime silicate glass p