CN112661531A - Silicon nitride whisker reinforced periclase-spinel-carbon filter and preparation method thereof - Google Patents
Silicon nitride whisker reinforced periclase-spinel-carbon filter and preparation method thereof Download PDFInfo
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Abstract
The invention relates to a silicon nitride whisker reinforced periclase-spinel-carbon filter and a preparation method thereof. The technical scheme isThe method comprises the following steps: mixing the modified periclase-spinel ceramic fine powder, the magnesia fine powder, the modified coal tar asphalt powder, the elemental silicon powder and the sodium carboxymethylcellulose, adding alumina sol, a water reducing agent, a defoaming agent and deionized water, and stirring to obtain ceramic slurry with thixotropy (hereinafter referred to as ceramic slurry). Immersing the pretreated polyurethane foam into the ceramic slurry, taking out the pretreated polyurethane foam, removing the redundant ceramic slurry, maintaining and drying; in N2Heating to 1200-1300 ℃ in the atmosphere, preserving heat and cooling; soaking the cooled periclase-spinel-carbon filter pre-sintered body in ceramic slurry, centrifuging, drying, and adding N2And preserving the heat under the conditions of the atmosphere and 1300-1400 ℃ to obtain the silicon nitride whisker reinforced periclase-spinel-carbon filter. The product prepared by the invention has the characteristics of high strength, excellent thermal shock stability and excellent filtering effect.
Description
Technical Field
The invention belongs to the technical field of filters. In particular to a silicon nitride whisker reinforced periclase-spinel-carbon filter and a preparation method thereof.
Background
The metal is a basic material for industrial manufacture, is a 'foundation stone' for national major engineering construction and major equipment manufacture, and has important significance for national economy and national defense construction in developing high-quality metal. The non-metallic inclusion in the metal can seriously affect the strength and the service life of the metal, and the quality of the metal can be effectively improved by removing the non-metallic inclusion and improving the purity of the molten metal. The introduction of a ceramic filter to filter impurities in molten metal in the final step of molten metal casting is an important way for effectively purifying the molten metal and improving the metal quality.
Currently, there is much research on molten metal filters, particularly magnesium and its alloys, and cast steel filters. For example, the patent technology of 'a spinel reinforced magnesia-based ceramic foam filter and a preparation method thereof' (201810307618.0) adopts magnesia ceramic powder as a raw material, and adds nano alumina sol, rheological agent and nano lanthanum oxide to prepare the spinel reinforced magnesia-based ceramic foam filter. The magnesia ceramic powder adopted by the technology is a compact raw material, so that the surface structure of the framework of the filter is relatively compact, the adsorption capacity to impurities is limited, and the thickness of the framework of the product is relatively low, so that the product has relatively low structural strength and relatively short service life.
For another example, the literature technique (Wangmongmeng, preparation and performance research of MgO foamed ceramics, Master academic thesis of Nanjing aerospace university, 2017) uses industrial MgO as raw material, and adds Al2O3The MgO foamed ceramic is prepared from polyvinyl alcohol, carboxymethyl cellulose and a low-temperature adhesive, but industrial MgO adopted by the technology is a compact raw material, so that the surface of a framework of the filter is compact, the adsorption capacity to nonmetallic inclusions is weak, and the filtering effect needs to be improved.
For another example, the patent of "a ceramic filter and a method for manufacturing the same" (201310050569.4) discloses a technique for manufacturing a ceramic filter by using materials such as zirconia, silica, alumina, magnesia, mullite, talc, feldspar and the like and biochar as raw materials and natural resin or silica sol as a binder, but the technique is too complex in material composition, and liquid phase is easily generated at high temperature to reduce the strength of the filter; meanwhile, the adopted raw materials are compact materials, so that the surface of the framework of the filter is compact, and the adsorption capacity to nonmetallic inclusions is weak; in addition, although this technique introduces carbon, since carbon belongs to an inert phase in the sintering theory, it is difficult to sinter, so that the interface compatibility between the oxide material and carbon is poor, limiting the strength of the product.
In summary, there are still some technical defects in the prior art regarding magnesium and its alloy melt and molten steel filter: (1) the composition is too complex, so that excessive liquid phase is easily generated in a high-temperature service environment, and the strength of the filter is reduced; (2) the MgO has large thermal expansion coefficient, and the thermal shock stability needs to be improved; (3) the surface of the filter framework is compact, the adsorption capacity to impurities is limited, and the filtering effect is limited; (4) when biochar is used as a raw material, oxides and carbon are difficult to sinter, interface compatibility is poor, and the strength of a product is limited.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and aims to provide a preparation method of a silicon nitride whisker reinforced periclase-spinel-carbon filter, and the silicon nitride whisker reinforced periclase-spinel-carbon filter prepared by the method has high strength, excellent thermal shock stability and excellent filtering effect; the method is suitable for the field of purification of high-quality molten steel and the field of purification of magnesium and magnesium alloy melts.
In order to achieve the purpose, the technical scheme adopted by the invention comprises the following steps:
step 1, preparation of periclase-spinel ceramic fine powder
Step 1.1, heating the fine aluminum hydroxide powder to 320-400 ℃ at the speed of 2-5 ℃/min, preserving the heat for 1-3 h, and cooling to obtain the high-porosity porous fine aluminum oxide powder.
Step 1.2, taking 10-40 wt% of the high-porosity porous alumina fine powder and 60-90 wt% of light-burned magnesite fine powder as raw materials, placing the raw materials in a stirrer, and stirring for 1-3 hours; and adding 3-6 wt% of alumina sol of the raw materials, and mixing for 10-20 min to obtain a mixture.
Step 1.3, performing mechanical pressing molding on the mixture under the condition of 100-150 MPa, and drying a molded blank at the temperature of 110 ℃ for 24-48 h; and then heating to 1600-1750 ℃ at the speed of 4-5 ℃/min, preserving the heat for 2-6 h, and cooling to obtain the micro-nano-aperture periclase-spinel ceramic.
The periclase-spinel ceramic with the micro-nano aperture comprises: an apparent porosity of 24 to 32% and a bulk density of 2.42 to 2.71g/cm3The average pore diameter of the pores is 600-1550 nm.
And step 1.4, crushing and screening the micro-nano-aperture periclase-spinel ceramic to obtain micro-nano-aperture periclase-spinel ceramic fine powder, wherein the particle size of the micro-nano-aperture periclase-spinel ceramic fine powder is less than 30 microns.
Step 2, preparation of modified periclase-spinel ceramic fine powder
And 2.1, placing the deionized water and the ferric nitrate nonahydrate into a stirrer according to the mass ratio of the deionized water to the ferric nitrate nonahydrate of 100: 1.5-5.5, and stirring for 10-20 min to obtain a modified solution.
And 2.2, placing the fine powder of the periclase-spinel ceramic with the micro-nano aperture in a vacuum device according to the mass ratio of the fine powder of the periclase-spinel ceramic with the micro-nano aperture to the modified solution of 100: 20-36, vacuumizing to 2.0-3.0 kPa, adding the modified solution, stirring for 15-30 min, closing a vacuumizing system, and naturally drying for 24-32 h to obtain the fine powder of the modified periclase-spinel ceramic.
Step 3, preparation of pretreated polyurethane foam
And (3) soaking 8-20 ppi polyurethane foam into NaOH solution for 2-4 h, taking out, washing with deionized water for 2-6 times, and airing to obtain the pretreated polyurethane foam.
Step 4, preparation of silicon nitride whisker reinforced periclase-spinel-carbon filter
Taking 75-85 wt% of modified periclase-spinel ceramic fine powder, 7-11 wt% of magnesite fine powder, 3-7 wt% of modified coal tar asphalt powder, 2.5-5 wt% of simple substance silicon powder and 0.5-3 wt% of sodium carboxymethyl cellulose as raw materials, placing the raw materials into a mixer, mixing for 2-5 h, adding 2-5 wt% of alumina sol, 0.04-0.15 wt% of water reducing agent, 0.3-1.3 wt% of defoaming agent and 20-35 wt% of deionized water, and stirring for 40-60 min to obtain ceramic slurry with thixotropy.
Immersing the pretreated polyurethane foam into the thixotropic ceramic slurry for 10-15 min, taking out, removing redundant ceramic slurry by using a pair roller machine, curing for 15-26 h at room temperature, and drying for 12-24 h at 80-110 ℃; then in N2Partial pressure of 1atm, O2Partial pressure of less than 1.0X 10-14.4Pa and CO partial pressure less than 1.0X 10-6.4And (3) under the condition of Pa atmosphere, heating to 1200-1300 ℃ at the speed of 0.5-2 ℃/min, preserving the heat for 2-4 h, and cooling to obtain the periclase-spinel-carbon filter pre-sintered body.
Dipping the periclase-spinel-carbon filter pre-sintered body into the ceramic slurry with thixotropy for 10-20 minutes, taking out, and then treating in a centrifuge at a rotating speed of 200-450 r/min for 3-5 minutes to obtain a secondary slurry coated periclase-spinel-carbon filter blank; naturally drying the secondary slurry coating periclase-spinel-carbon filter blank for 20-40 h, drying at 80-110 ℃ for 12-36 h, and then drying in N2Partial pressure of 1atm, O2Partial pressure of less than 1.0X 10-14.4Pa and CO partial pressure less than 1.0X 10-6.4And (3) heating to 1300-1400 ℃ at the speed of 2-6 ℃/min under the atmosphere condition of Pa, preserving the heat for 3-6 h, and cooling to obtain the silicon nitride whisker reinforced periclase-spinel-carbon filter.
The particle size of the aluminum hydroxide fine powder is less than 44 mu m; al of the aluminum hydroxide fine powder2O3The content is 64-66 wt%.
The particle size of the light-burned magnesite fine powder is less than 44 mu m; the MgO content of the light-burned magnesite fine powder is more than 95 wt%.
1.2, the aluminum sol is the same as the aluminum sol in the step 4; al of the aluminum sol2O3The content is 20-45 wt%.
Fe (NO) of the iron nitrate nonahydrate3)3·9H2The O content is more than 98 wt%.
The solvent of the NaOH solution is deionized water; the concentration of the NaOH solution is 6-8 mol/L.
The particle size of the magnesite fine powder is less than 44 mu m; the MgO content of the magnesite fine powder is more than 96 wt%.
The particle size of the modified coal tar asphalt powder is less than 74 mu m; the C content of the modified coal tar asphalt powder is more than 70 wt%.
The particle size of the elemental silicon powder is less than 45 μm; the Si content of the elemental silicon powder is more than 98 wt%.
The water reducing agent is sodium lignosulphonate or polycarboxylate; the content of lignin in the sodium lignosulphonate is 45-60 wt%, and the molecular weight of a side chain in the polycarboxylate is 700-2300.
Due to the adoption of the technical scheme, compared with the prior art, the invention has the following positive effects:
(1) the invention uses the modified periclase-spinel ceramic fine powder as a raw material to form a sawtooth occlusion interface and silicon nitride whiskers with special distribution, thereby obviously improving the strength and the thermal shock stability of the product.
The method directly takes porous alumina fine powder and light calcined magnesite fine powder with high porosity as raw materials, does not need to additionally add pore-forming agents, controls the microstructure of the periclase-spinel ceramic fine powder through alumina sol, special forming pressure and a firing system, and obtains the periclase-spinel ceramic fine powder which can be applied to high-temperature service conditions and has a micro-nano porous structure. The fine powder has a rough surface structure, the contact area between the fine powder/the fine powder and the fine powder/the modified coal tar asphalt powder is increased, the material transmission rate is accelerated in the sintering process, solid-solid neck connection is formed, a sawtooth occlusion-shaped interface is formed among micro-particles, and the product strength is improved.
Secondly, the modified periclase-spinel ceramic fine powder with through air holes is used as a raw material, the surface structure is rough, the contact area of ceramic slurry and a polyurethane foam template is increased, the thickness of a framework is increased by utilizing a special secondary slurry hanging process, the hollow structure of a product is avoided, and the strength of the product is improved.
The invention utilizes the micro-nano porous structure of the modified periclase-spinel ceramic fine powder and the catalyst attached inside to promote the in-situ generation of the silicon nitride whiskers in the surface and the internal holes, and the silicon nitride whiskers generated in situ in the matrix form a special net-shaped interweaving structure, thereby further improving the strength and the thermal shock stability of the product. Solves the problems that the existing silicon nitride crystal whisker can only be formed in the matrix gap and has poor interface compatibility.
And fourthly, when the material is subjected to the action of rapid change of the environmental temperature in the using process, microcracks are generated at weak positions of the material, the composite reinforcement is realized by utilizing a sawtooth-meshed interface and specially-distributed silicon nitride whiskers, destructive stress is absorbed, when the cracks are expanded and meet the micro-nano holes and the silicon nitride whiskers, the holes and the whiskers can inhibit the accumulation of strain energy, and the instantaneous expansion of the cracks is prevented, so that the thermal shock stability of the product is improved.
(2) The invention utilizes the special micro-nano porous structure of the periclase-spinel-carbon filter and combines with the carbothermic reduction reaction, thereby improving the adsorption capacity to the impurities and improving the purification effect.
The modified periclase-spinel ceramic fine powder is used as a raw material, so that a product framework has a micro-nano porous structure, the specific surface area of the framework is increased, the product framework can be fully contacted with molten steel, and the adsorption capacity on impurities is improved.
The method combines the carbothermic reduction reaction, MgO, spinel, C and molten steel are easy to react to form an active magnesium aluminate spinel layer at the interface of a product skeleton and the molten steel, the MgO and the C are subjected to the carbothermic reduction reaction to form Mg steam under the high-temperature service condition, and the Mg steam enters the molten steel through micro-nano air holes in the product, so that the effect of a strong deoxidizer is achieved, and the total oxygen content of the molten steel is reduced; meanwhile, Mg vapor reacts with other inclusions to form larger-size inclusions, so that the inclusions float upwards easily, and the filtering effect is enhanced.
In the high-temperature service process, MgO reacts with C, and formed gases such as CO are dissipated into molten steel through micro-nano air holes in the framework to form micron-sized bubbles, so that small-size inclusions in the molten steel can be adsorbed, the inclusions in the molten steel are further reduced, and the purification effect of products is improved.
The silicon nitride whisker reinforced periclase-spinel-carbon filter prepared by the invention is detected as follows: the apparent porosity is 80-90%; the bulk density is 0.39-0.71 g/cm3(ii) a The compressive strength is 1.5-3.6 MPa; the phase composition mainly comprises periclase, magnesium aluminate spinel, graphite and beta-Si3N4And a small amount of MgAlON.
Therefore, the silicon nitride whisker reinforced periclase-spinel-carbon filter prepared by the method has high strength, excellent thermal shock stability and excellent filtering effect; the method is suitable for the field of purification of high-quality molten steel and the field of purification of magnesium and magnesium alloy melts.
Detailed Description
The invention is further described with reference to specific embodiments, without limiting its scope.
A silicon nitride whisker reinforced periclase-spinel-carbon filter and a preparation method thereof. The preparation method of the embodiment comprises the following steps:
step 1, preparation of periclase-spinel ceramic fine powder
Step 1.1, heating the fine aluminum hydroxide powder to 320-400 ℃ at the speed of 2-5 ℃/min, preserving the heat for 1-3 h, and cooling to obtain the high-porosity porous fine aluminum oxide powder.
Step 1.2, taking 10-40 wt% of the high-porosity porous alumina fine powder and 60-90 wt% of light-burned magnesite fine powder as raw materials, placing the raw materials in a stirrer, and stirring for 1-3 hours; and adding 3-6 wt% of alumina sol of the raw materials, and mixing for 10-20 min to obtain a mixture.
Step 1.3, performing mechanical pressing molding on the mixture under the condition of 100-150 MPa, and drying a molded blank at the temperature of 110 ℃ for 24-48 h; and then heating to 1600-1750 ℃ at the speed of 4-5 ℃/min, preserving the heat for 2-6 h, and cooling to obtain the micro-nano-aperture periclase-spinel ceramic.
The periclase-spinel ceramic with the micro-nano aperture comprises: an apparent porosity of 24 to 32% and a bulk density of 2.42 to 2.71g/cm3The average pore diameter of the pores is 600-1550 nm.
And step 1.4, crushing and screening the micro-nano-aperture periclase-spinel ceramic to obtain micro-nano-aperture periclase-spinel ceramic fine powder, wherein the particle size of the micro-nano-aperture periclase-spinel ceramic fine powder is less than 30 microns.
Step 2, preparation of modified periclase-spinel ceramic fine powder
And 2.1, placing the deionized water and the ferric nitrate nonahydrate into a stirrer according to the mass ratio of the deionized water to the ferric nitrate nonahydrate of 100: 1.5-5.5, and stirring for 10-20 min to obtain a modified solution.
And 2.2, placing the fine powder of the periclase-spinel ceramic with the micro-nano aperture in a vacuum device according to the mass ratio of the fine powder of the periclase-spinel ceramic with the micro-nano aperture to the modified solution of 100: 20-36, vacuumizing to 2.0-3.0 kPa, adding the modified solution, stirring for 15-30 min, closing a vacuumizing system, and naturally drying for 24-32 h to obtain the fine powder of the modified periclase-spinel ceramic.
Step 3, preparation of pretreated polyurethane foam
And (3) soaking 8-20 ppi polyurethane foam into NaOH solution for 2-4 h, taking out, washing with deionized water for 2-6 times, and airing to obtain the pretreated polyurethane foam.
Step 4, preparation of silicon nitride whisker reinforced periclase-spinel-carbon filter
Taking 75-85 wt% of modified periclase-spinel ceramic fine powder, 7-11 wt% of magnesite fine powder, 3-7 wt% of modified coal tar asphalt powder, 2.5-5 wt% of simple substance silicon powder and 0.5-3 wt% of sodium carboxymethyl cellulose as raw materials, placing the raw materials into a mixer, mixing for 2-5 h, adding 2-5 wt% of alumina sol, 0.04-0.15 wt% of water reducing agent, 0.3-1.3 wt% of defoaming agent and 20-35 wt% of deionized water, and stirring for 40-60 min to obtain ceramic slurry with thixotropy.
Immersing the pretreated polyurethane foam into the thixotropic ceramic slurry for 10-15 min, taking out, removing redundant ceramic slurry by using a pair roller machine, curing for 15-26 h at room temperature, and drying for 12-24 h at 80-110 ℃; then in N2Partial pressure of 1atm, O2Partial pressure of less than 1.0X 10-14.4Pa and CO partial pressure less than 1.0X 10-6.4And (3) under the condition of Pa atmosphere, heating to 1200-1300 ℃ at the speed of 0.5-2 ℃/min, preserving the heat for 2-4 h, and cooling to obtain the periclase-spinel-carbon filter pre-sintered body.
Dipping the periclase-spinel-carbon filter pre-sintered body into the ceramic slurry with thixotropy for 10-20 minutes, taking out, and then treating in a centrifuge at a rotating speed of 200-450 r/min for 3-5 minutes to obtain a secondary slurry coated periclase-spinel-carbon filter blank; naturally drying the secondary slurry coating periclase-spinel-carbon filter blank for 20-40 h, drying at 80-110 ℃ for 12-36 h, and then drying in N2Partial pressure of 1atm, O2Partial pressure of less than 1.0X 10-14.4Pa and CO partial pressure less than 1.0X 10-6.4And (3) heating to 1300-1400 ℃ at the speed of 2-6 ℃/min under the atmosphere condition of Pa, preserving the heat for 3-6 h, and cooling to obtain the silicon nitride whisker reinforced periclase-spinel-carbon filter.
Al of the aluminum hydroxide fine powder2O3The content is 64-66 wt%.
The MgO content of the light-burned magnesite fine powder is more than 95 wt%.
Al of the aluminum sol2O3The content is 20-45 wt%.
Fe (NO) of the iron nitrate nonahydrate3)3·9H2The O content is more than 98 wt%.
The concentration of the NaOH solution is 6-8 mol/L.
The MgO content of the magnesite fine powder is more than 96 wt%.
The C content of the modified coal tar asphalt powder is more than 70 wt%.
The Si content of the elemental silicon powder is more than 98 wt%.
The water reducing agent is sodium lignosulphonate or polycarboxylate; the content of lignin in the sodium lignosulphonate is 45-60 wt%, and the molecular weight of a side chain in the polycarboxylate is 700-2300.
In this embodiment:
the particle size of the aluminum hydroxide fine powder is less than 44 mu m;
the particle size of the light-burned magnesite fine powder is less than 44 mu m;
the solvent of the NaOH solution is deionized water;
the particle size of the magnesite fine powder is less than 44 mu m;
the particle size of the modified coal tar asphalt powder is less than 74 mu m;
the particle size of the elemental silicon powder is less than 45 μm;
the aluminum sol in the step 1.2 is the same as the aluminum sol in the step 4.
The detailed description is omitted in the embodiments.
Example 1
A silicon nitride whisker reinforced periclase-spinel-carbon filter and a preparation method thereof. The preparation method of the embodiment comprises the following steps:
step 1, preparation of periclase-spinel ceramic fine powder
Step 1.1, heating the fine aluminum hydroxide powder to 320 ℃ at the speed of 2 ℃/min, preserving the heat for 1h, and cooling to obtain the high-porosity porous fine aluminum oxide powder.
Step 1.2, taking 10 wt% of the high-porosity porous alumina fine powder and 90 wt% of light-burned magnesite fine powder as raw materials, placing the raw materials in a stirrer, and stirring for 1 hour; adding 3 wt% of alumina sol of the raw materials, and mixing for 10min to obtain a mixture.
Step 1.3, performing mechanical pressing molding on the mixture under the condition of 100MPa, and drying a molded blank at the temperature of 110 ℃ for 24 hours; and then heating to 1600 ℃ at the speed of 4 ℃/min, preserving the heat for 2h, and cooling to obtain the micro-nano-aperture periclase-spinel ceramic.
The periclase-spinel ceramic with the micro-nano aperture comprises: the apparent porosity is 24 percent, and the volume density is 2.71g/cm3The average pore diameter of the pores was 600 nm.
And step 1.4, crushing and screening the micro-nano-aperture periclase-spinel ceramic to obtain micro-nano-aperture periclase-spinel ceramic fine powder, wherein the particle size of the micro-nano-aperture periclase-spinel ceramic fine powder is less than 30 microns.
Step 2, preparation of modified periclase-spinel ceramic fine powder
And 2.1, placing the deionized water and the ferric nitrate nonahydrate into a stirrer according to the mass ratio of the deionized water to the ferric nitrate nonahydrate of 100: 1.5, and stirring for 10min to obtain a modified solution.
And 2.2, placing the micro-nano-aperture periclase-spinel ceramic fine powder in a vacuum device according to the mass ratio of the micro-nano-aperture periclase-spinel ceramic fine powder to the modified solution of 100: 20, vacuumizing to 2kPa, adding the modified solution, stirring for 15min, closing a vacuumizing system, and naturally drying for 24h to obtain the modified periclase-spinel ceramic fine powder.
Step 3, preparation of pretreated polyurethane foam
And (2) soaking 8ppi polyurethane foam in NaOH solution for 2h, taking out, washing with deionized water for 2 times, and airing to obtain the pretreated polyurethane foam.
Step 4, preparation of silicon nitride whisker reinforced periclase-spinel-carbon filter
Taking 75 wt% of modified periclase-spinel ceramic fine powder, 11 wt% of magnesite fine powder, 7 wt% of modified coal tar asphalt powder, 4 wt% of elemental silicon powder and 3 wt% of sodium carboxymethylcellulose as raw materials, putting the raw materials into a mixer, mixing for 2 hours, adding 2 wt% of alumina sol, 0.04 wt% of water reducing agent, 0.3 wt% of defoaming agent and 20 wt% of deionized water as the raw materials, and stirring for 40 minutes to obtain ceramic slurry with thixotropy.
Immersing the pretreated polyurethane foam into the thixotropic ceramic slurry for 10min, taking out, removing redundant ceramic slurry by using a double-roller machine, maintaining for 15h at room temperature, and drying for 12h at 80 ℃; then in N2Partial pressure of 1atm, O2Partial pressure of less than 1.0X 10-14.4Pa and CO partial pressure less than 1.0X 10-6.4And (3) under the condition of Pa atmosphere, heating to 1200 ℃ at the speed of 0.5 ℃/min, preserving the heat for 2h, and cooling to obtain the periclase-spinel-carbon filter pre-sintered body.
Dipping the periclase-spinel-carbon filter pre-sintered body into the ceramic slurry with thixotropy for 10 minutes, taking out the body, and then treating the body in a centrifuge at a rotating speed of 200r/min for 3 minutes to obtain a secondary slurry-coated periclase-spinel-carbon filter blank; naturally drying the secondary slurry periclase-spinel-carbon filter blank for 20h, drying at 80 ℃ for 12h, and then drying in N2Partial pressure of 1atm, O2Partial pressure of less than 1.0X 10-14.4Pa and CO partial pressure less than 1.0X 10-6.4And (3) heating to 1300 ℃ at the speed of 2 ℃/min under the atmosphere condition of Pa, preserving the heat for 3h, and cooling to obtain the silicon nitride whisker reinforced periclase-spinel-carbon filter.
Al of the aluminum hydroxide fine powder2O3The content was 64.07 wt%.
The MgO content of the light-burned magnesite fine powder is 95.3 wt%.
Al of the aluminum sol2O3The content was 20 wt%.
Fe (NO) of the iron nitrate nonahydrate3)3·9H2The O content was 99.2 wt%.
The concentration of the NaOH solution is 6 mol/L.
The MgO content of the magnesite fine powder is 96.2 wt%.
The C content of the modified coal tar asphalt powder is 71.15 wt%.
The Si content of the elemental silicon powder is 98.32 wt%.
The water reducing agent is sodium lignosulphonate, and the lignin content in the sodium lignosulphonate is 48 wt%.
The silicon nitride whisker reinforced periclase-spinel-carbon filter prepared in this example was tested: the apparent porosity is 90%; the bulk density is 0.39g/cm3(ii) a The compressive strength is 1.5 MPa; the phase composition mainly comprises periclase, magnesium aluminate spinel, graphite and beta-Si3N4And a small amount of MgAlON.
Example 2
A silicon nitride whisker reinforced periclase-spinel-carbon filter and a preparation method thereof. The preparation method of the embodiment comprises the following steps:
step 1, preparation of periclase-spinel ceramic fine powder
Step 1.1, heating the fine aluminum hydroxide powder to 350 ℃ at the speed of 3 ℃/min, preserving the heat for 2h, and cooling to obtain the high-porosity porous fine aluminum oxide powder.
Step 1.2, taking 20 wt% of the high-porosity porous alumina fine powder and 80 wt% of light-burned magnesite fine powder as raw materials, placing the raw materials in a stirrer, and stirring for 2.5 hours; adding 4 wt% of alumina sol of the raw materials, and mixing for 14min to obtain a mixture.
Step 1.3, performing mechanical pressing molding on the mixture under the condition of 120MPa, and drying a molded blank at the temperature of 110 ℃ for 30 h; and then heating to 1680 ℃ at the speed of 4 ℃/min, preserving the heat for 4h, and cooling to obtain the micro-nano-aperture periclase-spinel ceramic.
The periclase-spinel ceramic with the micro-nano aperture comprises: the apparent porosity was 26.4%, and the bulk density was 2.64g/cm3The average pore diameter of the pores was 860 nm.
And step 1.4, crushing and screening the micro-nano-aperture periclase-spinel ceramic to obtain micro-nano-aperture periclase-spinel ceramic fine powder, wherein the particle size of the micro-nano-aperture periclase-spinel ceramic fine powder is less than 30 microns.
Step 2, preparation of modified periclase-spinel ceramic fine powder
And 2.1, placing the deionized water and the ferric nitrate nonahydrate into a stirrer according to the mass ratio of the deionized water to the ferric nitrate nonahydrate of 100: 2.8, and stirring for 13min to obtain a modified solution.
And 2.2, placing the micro-nano-aperture periclase-spinel ceramic fine powder in a vacuum device according to the mass ratio of the micro-nano-aperture periclase-spinel ceramic fine powder to the modified solution of 100: 26, vacuumizing to 2.3kPa, adding the modified solution, stirring for 18min, closing a vacuumizing system, and naturally drying for 26h to obtain the modified periclase-spinel ceramic fine powder.
Step 3, preparation of pretreated polyurethane foam
And (2) soaking 12ppi of polyurethane foam in NaOH solution for 3h, taking out, washing with deionized water for 3 times, and airing to obtain the pretreated polyurethane foam.
Step 4, preparation of silicon nitride whisker reinforced periclase-spinel-carbon filter
Taking 78.5 wt% of modified periclase-spinel ceramic fine powder, 9.7 wt% of magnesite fine powder, 6 wt% of modified coal tar asphalt powder, 3.3 wt% of simple substance silicon powder and 2.5 wt% of sodium carboxymethyl cellulose as raw materials, putting the raw materials into a mixer, mixing for 3 hours, adding 3 wt% of alumina sol, 0.08 wt% of water reducing agent, 0.6 wt% of defoaming agent and 26 wt% of deionized water as the raw materials, and stirring for 46 minutes to obtain ceramic slurry with thixotropy.
Immersing the pretreated polyurethane foam into the thixotropic ceramic slurry for 12min, taking out, removing redundant ceramic slurry by using a double-roller machine, curing for 18h at room temperature, and drying for 17h at 90 ℃; then in N2Partial pressure of 1atm, O2Partial pressure of less than 1.0X 10-14.4Pa and CO partial pressure less than 1.0X 10-6.4And (3) under the atmosphere condition of Pa, heating to 1230 ℃ at the speed of 1 ℃/min, preserving the heat for 3h, and cooling to obtain the periclase-spinel-carbon filter pre-sintered body.
Dipping the periclase-spinel-carbon filter pre-sintered body in the pottery with thixotropySoaking in the ceramic slurry for 13 minutes, taking out, and treating in a centrifuge at a rotating speed of 270r/min for 4 minutes to obtain a secondary slurry coating periclase-spinel-carbon filter blank; naturally drying the secondary slurry-periclase-spinel-carbon filter blank for 26h, drying at 90 ℃ for 20h, and then drying in N2Partial pressure of 1atm, O2Partial pressure of less than 1.0X 10-14.4Pa and CO partial pressure less than 1.0X 10-6.4And (3) heating to 1330 ℃ at the speed of 3 ℃/min under the atmosphere condition of Pa, preserving the temperature for 4h, and cooling to obtain the silicon nitride whisker reinforced periclase-spinel-carbon filter.
Al of the aluminum hydroxide fine powder2O3The content was 64.79 wt%.
The MgO content of the light-burned magnesite fine powder is 95.87 wt%.
Al of the aluminum sol2O3The content was 28 wt%.
Fe (NO) of the iron nitrate nonahydrate3)3·9H2The O content was 99.4 wt%.
The concentration of the NaOH solution is 6.6 mol/L.
The MgO content of the magnesite fine powder is 96.6 wt%.
The C content of the modified coal tar asphalt powder is 72.47 wt%.
The Si content of the elemental silicon powder is 98.91 wt%.
The water reducing agent is polycarboxylate, and the molecular weight of a side chain in the polycarboxylate is 1000.
The silicon nitride whisker reinforced periclase-spinel-carbon filter prepared in this example was tested: the apparent porosity is 87%; the bulk density is 0.46g/cm3(ii) a The compressive strength is 1.8 MPa; the phase composition mainly comprises periclase, magnesium aluminate spinel, graphite and beta-Si3N4And a small amount of MgAlON.
Example 3
A silicon nitride whisker reinforced periclase-spinel-carbon filter and a preparation method thereof. The preparation method of the embodiment comprises the following steps:
step 1, preparation of periclase-spinel ceramic fine powder
Step 1.1, heating the fine aluminum hydroxide powder to 380 ℃ at the speed of 4 ℃/min, preserving the heat for 2.5h, and cooling to obtain the high-porosity porous alumina fine powder.
Step 1.2, taking 30 wt% of the high-porosity porous alumina fine powder and 70 wt% of light-burned magnesite fine powder as raw materials, placing the raw materials in a stirrer, and stirring for 2 hours; and adding 5 wt% of alumina sol of the raw materials, and mixing for 17min to obtain a mixture.
Step 1.3, performing mechanical pressing molding on the mixture under the condition of 130MPa, and drying the molded blank at the temperature of 110 ℃ for 40 h; and then heating to 1710 ℃ at the speed of 5 ℃/min, preserving the heat for 5h, and cooling to obtain the micro-nano-aperture periclase-spinel ceramic.
The periclase-spinel ceramic with the micro-nano aperture comprises: the apparent porosity was 29.7%, and the bulk density was 2.54g/cm3The average pore diameter of the pores is 1270 nm.
And step 1.4, crushing and screening the micro-nano-aperture periclase-spinel ceramic to obtain micro-nano-aperture periclase-spinel ceramic fine powder, wherein the particle size of the micro-nano-aperture periclase-spinel ceramic fine powder is less than 30 microns.
Step 2, preparation of modified periclase-spinel ceramic fine powder
And 2.1, placing the deionized water and the ferric nitrate nonahydrate into a stirrer according to the mass ratio of the deionized water to the ferric nitrate nonahydrate of 100: 4, and stirring for 17min to obtain a modified solution.
And 2.2, putting the micro-nano-aperture periclase-spinel ceramic fine powder into a vacuum device according to the mass ratio of the micro-nano-aperture periclase-spinel ceramic fine powder to the modified solution of 100: 30, vacuumizing to 2.7kPa, adding the modified solution, stirring for 25min, closing a vacuumizing system, and naturally drying for 29h to obtain the modified periclase-spinel ceramic fine powder.
Step 3, preparation of pretreated polyurethane foam
And (2) soaking 16ppi of polyurethane foam in NaOH solution for 3h, taking out, washing with deionized water for 5 times, and airing to obtain the pretreated polyurethane foam.
Step 4, preparation of silicon nitride whisker reinforced periclase-spinel-carbon filter
Taking 82.3 wt% of modified periclase-spinel ceramic fine powder, 8.2 wt% of magnesite fine powder, 3 wt% of modified coal tar asphalt powder, 5 wt% of simple substance silicon powder and 1.5 wt% of sodium carboxymethyl cellulose as raw materials, putting the raw materials into a mixer, mixing for 4 hours, adding 4 wt% of alumina sol, 0.11 wt% of water reducing agent, 0.9 wt% of defoaming agent and 28 wt% of deionized water as the raw materials, and stirring for 52 minutes to obtain ceramic slurry with thixotropy.
Immersing the pretreated polyurethane foam into the thixotropic ceramic slurry for 13min, taking out, removing redundant ceramic slurry by using a double-roller machine, curing for 22h at room temperature, and drying for 20h at 100 ℃; then in N2Partial pressure of 1atm, O2Partial pressure of less than 1.0X 10-14.4Pa and CO partial pressure less than 1.0X 10-6.4And (3) heating to 1260 ℃ at the speed of 1.5 ℃/min under the atmosphere condition of Pa, preserving the heat for 3h, and cooling to obtain the periclase-spinel-carbon filter pre-sintered body.
Dipping the periclase-spinel-carbon filter pre-sintered body into the ceramic slurry with thixotropy for 17 minutes, taking out the body, and then treating the body in a centrifuge at the rotating speed of 350r/min for 4 minutes to obtain a secondary slurry-coated periclase-spinel-carbon filter blank; naturally drying the secondary slurry periclase-spinel-carbon filter blank for 33h, drying at 100 ℃ for 28h, and then drying in N2Partial pressure of 1atm, O2Partial pressure of less than 1.0X 10-14.4Pa and CO partial pressure less than 1.0X 10-6.4And (3) heating to 1370 ℃ at the speed of 5 ℃/min under the atmosphere condition of Pa, preserving the heat for 5h, and cooling to obtain the silicon nitride whisker reinforced periclase-spinel-carbon filter.
Al of the aluminum hydroxide fine powder2O3The content was 65.14 wt%.
The MgO content of the light-burned magnesite fine powder is 96.21 wt%.
Al of the aluminum sol2O3The content was 36 wt%.
Fe (NO) of the iron nitrate nonahydrate3)3·9H2The O content was 98.5 wt%.
The concentration of the NaOH solution is 7.1 mol/L.
The MgO content of the magnesite fine powder is 96.9 wt%.
The C content of the modified coal tar asphalt powder is 73.26 wt%.
The Si content of the elemental silicon powder is 99.06 wt%.
The water reducing agent is sodium lignosulphonate, and the lignin content in the sodium lignosulphonate is 58 wt%.
The silicon nitride whisker reinforced periclase-spinel-carbon filter prepared in this example was tested: the apparent porosity is 82%; the bulk density is 0.6g/cm3(ii) a The compressive strength is 2.7 MPa; the phase composition mainly comprises periclase, magnesium aluminate spinel, graphite and beta-Si3N4And a small amount of MgAlON.
Example 4
A silicon nitride whisker reinforced periclase-spinel-carbon filter and a preparation method thereof. The preparation method of the embodiment comprises the following steps:
step 1, preparation of periclase-spinel ceramic fine powder
Step 1.1, heating the fine aluminum hydroxide powder to 400 ℃ at the speed of 5 ℃/min, preserving the heat for 3h, and cooling to obtain the high-porosity porous fine aluminum oxide powder.
Step 1.2, taking 40 wt% of the high-porosity porous alumina fine powder and 60 wt% of light-burned magnesite fine powder as raw materials, placing the raw materials in a stirrer, and stirring for 3 hours; adding 6 wt% of alumina sol of the raw materials, and mixing for 20min to obtain a mixture.
Step 1.3, performing mechanical pressing molding on the mixture under the condition of 150MPa, and drying a molded blank at the temperature of 110 ℃ for 48 hours; and then heating to 1750 ℃ at the speed of 5 ℃/min, preserving the heat for 6 hours, and cooling to obtain the micro-nano-aperture periclase-spinel ceramic.
The periclase-spinel ceramic with the micro-nano aperture comprises: the apparent porosity is 32 percent, and the volume density is 2.42g/cm3Average pore diameter of poresIs 1550 nm.
And step 1.4, crushing and screening the micro-nano-aperture periclase-spinel ceramic to obtain micro-nano-aperture periclase-spinel ceramic fine powder, wherein the particle size of the micro-nano-aperture periclase-spinel ceramic fine powder is less than 30 microns.
Step 2, preparation of modified periclase-spinel ceramic fine powder
And 2.1, placing the deionized water and the ferric nitrate nonahydrate into a stirrer according to the mass ratio of the deionized water to the ferric nitrate nonahydrate of 100: 5.5, and stirring for 20min to obtain a modified solution.
And 2.2, putting the micro-nano-aperture periclase-spinel ceramic fine powder into a vacuum device according to the mass ratio of the micro-nano-aperture periclase-spinel ceramic fine powder to the modified solution of 100: 36, vacuumizing to 3kPa, adding the modified solution, stirring for 30min, closing a vacuumizing system, and naturally drying for 32h to obtain the modified periclase-spinel ceramic fine powder.
Step 3, preparation of pretreated polyurethane foam
And (2) soaking 20ppi of polyurethane foam into NaOH solution for 4h, taking out, washing with deionized water for 6 times, and airing to obtain the pretreated polyurethane foam.
Step 4, preparation of silicon nitride whisker reinforced periclase-spinel-carbon filter
Taking 85 wt% of modified periclase-spinel ceramic fine powder, 7 wt% of magnesite fine powder, 5 wt% of modified coal tar asphalt powder, 2.5 wt% of simple substance silicon powder and 0.5 wt% of sodium carboxymethyl cellulose as raw materials, putting the raw materials into a mixer, mixing for 5 hours, adding 5 wt% of alumina sol, 0.15 wt% of water reducing agent, 1.3 wt% of defoaming agent and 35 wt% of deionized water, and stirring for 60 minutes to obtain ceramic slurry with thixotropy.
Immersing the pretreated polyurethane foam into the thixotropic ceramic slurry for 15min, taking out, removing redundant ceramic slurry by using a double-roller machine, maintaining for 26h at room temperature, and drying for 24h at 110 ℃; then in N2Partial pressure of 1atm, O2The partial pressure is less than 1.0×10-14.4Pa and CO partial pressure less than 1.0X 10-6.4And (3) under the atmosphere condition of Pa, heating to 1300 ℃ at the speed of 2 ℃/min, preserving the heat for 4h, and cooling to obtain the periclase-spinel-carbon filter pre-sintered body.
Dipping the periclase-spinel-carbon filter pre-sintered body into the ceramic slurry with thixotropy for 20 minutes, taking out the body, and then treating the body in a centrifuge at the rotating speed of 450r/min for 5 minutes to obtain a secondary slurry-coated periclase-spinel-carbon filter blank; naturally drying the secondary slurry periclase-spinel-carbon filter blank for 40h, drying at 110 ℃ for 36h, and then carrying out N2Partial pressure of 1atm, O2Partial pressure of less than 1.0X 10-14.4Pa and CO partial pressure less than 1.0X 10-6.4And (3) under the atmosphere condition of Pa, heating to 1400 ℃ at the speed of 6 ℃/min, preserving the heat for 6h, and cooling to obtain the silicon nitride whisker reinforced periclase-spinel-carbon filter.
Al of the aluminum hydroxide fine powder2O3The content was 65.93 wt%.
The MgO content of the light-burned magnesite fine powder is 96.91 wt%.
Al of the aluminum sol2O3The content was 45 wt%.
Fe (NO) of the iron nitrate nonahydrate3)3·9H2The O content was 98.6 wt%.
The concentration of the NaOH solution is 8 mol/L.
The MgO content of the magnesite fine powder is 97.1 wt%.
The C content of the modified coal tar asphalt powder is 74.12 wt%.
The Si content of the elemental silicon powder is 99.52 wt%.
The water reducing agent is polycarboxylate, and the molecular weight of a side chain in the polycarboxylate is 2000.
The silicon nitride whisker reinforced periclase-spinel-carbon filter prepared in this example was tested: the apparent porosity is 80%; the bulk density is 0.71g/cm3(ii) a The compressive strength is 3.6 MPa; the phase composition mainly comprises periclase, magnesium aluminate spinel, graphite and beta-Si3N4And a small amount of magnesiumAnd (4) a long ring.
Compared with the prior art, the specific implementation mode has the following positive effects:
(1) in the specific embodiment, the modified periclase-spinel ceramic fine powder is used as a raw material to form a sawtooth occlusion interface and silicon nitride whiskers with special distribution, so that the strength and the thermal shock stability of the product are obviously improved.
The specific implementation mode directly takes porous alumina fine powder and light calcined magnesite fine powder with high porosity as raw materials, does not need to additionally add pore-forming agents, and controls the microstructure of the periclase-spinel ceramic fine powder through alumina sol, special forming pressure and a sintering system to obtain the periclase-spinel ceramic fine powder which can be applied to high-temperature service conditions and has a micro-nano porous structure. The fine powder has a rough surface structure, the contact area between the fine powder/the fine powder and the fine powder/the modified coal tar asphalt powder is increased, the material transmission rate is accelerated in the sintering process, solid-solid neck connection is formed, a sawtooth occlusion-shaped interface is formed among micro-particles, and the product strength is improved.
Secondly, the specific embodiment takes the modified periclase-spinel ceramic fine powder with through air holes as a raw material, the surface structure is rough, the contact area of the ceramic slurry and a polyurethane foam template is increased, the thickness of the framework is increased by utilizing a special secondary slurry hanging process, the product is prevented from forming a hollow structure, and the strength of the product is improved.
The embodiment utilizes the micro-nano porous structure of the modified periclase-spinel ceramic fine powder and the catalyst attached inside to promote the in-situ generation of the silicon nitride whiskers in the surface and the internal holes and form a special reticular interweaving structure with the silicon nitride whiskers generated in situ in the matrix, thereby further improving the strength and the thermal shock stability of the product. Solves the problems that the existing silicon nitride crystal whisker can only be formed in the matrix gap and has poor interface compatibility.
And fourthly, when the material is subjected to the action of rapid change of the environmental temperature in the using process, microcracks are generated at weak positions of the material, the specific embodiment utilizes a sawtooth-meshed interface and specially-distributed silicon nitride whiskers to compositely reinforce and absorb destructive stress, and when the cracks expand and meet the micro-nano holes and the silicon nitride whiskers, the holes and the whiskers can inhibit the accumulation of strain energy and prevent the instantaneous expansion of the cracks, so that the thermal shock stability of the product is improved.
(2) The specific embodiment utilizes the special micro-nano porous structure of the periclase-spinel-carbon filter and combines with the carbothermic reduction reaction, thereby improving the adsorption capacity to the impurities and improving the purification effect.
The specific embodiment adopts the modified periclase-spinel ceramic fine powder as the raw material, so that the product framework has a micro-nano porous structure, the specific surface area of the framework is increased, the product framework can be fully contacted with molten steel, and the adsorption capacity on impurities is improved.
The specific embodiment combines with carbothermic reduction reaction, MgO, spinel, C and molten steel are easy to react to form an active magnesium aluminate spinel layer at the interface of a product skeleton and the molten steel, under the condition of high-temperature service, the MgO and the C are subjected to the carbothermic reduction reaction to form Mg steam, and the Mg steam enters the molten steel through micro-nano air holes in the product, thereby playing the role of a strong deoxidizer and reducing the total oxygen content of the molten steel; meanwhile, Mg vapor reacts with other inclusions to form larger-size inclusions, so that the inclusions float upwards easily, and the filtering effect is enhanced.
In the high-temperature service process, MgO reacts with C, and formed gases such as CO are dissipated into molten steel through micro-nano air holes in the framework to form micron-sized bubbles, so that small-size inclusions in the molten steel can be adsorbed, the inclusions in the molten steel are further reduced, and the purification effect of products is improved.
The silicon nitride whisker reinforced periclase-spinel-carbon filter prepared by the embodiment is detected as follows: the apparent porosity is 80-90%; the bulk density is 0.39-0.71 g/cm3(ii) a The compressive strength is 1.5-3.6 MPa; the phase composition mainly comprises periclase, magnesium aluminate spinel, graphite and beta-Si3N4And a small amount of MgAlON.
Therefore, the silicon nitride whisker reinforced periclase-spinel-carbon filter prepared by the embodiment has high strength, excellent thermal shock stability and excellent filtering effect; the method is suitable for the field of purification of high-quality molten steel and the field of purification of magnesium and magnesium alloy melts.
Claims (10)
1. A method for preparing a silicon nitride whisker reinforced periclase-spinel-carbon filter, characterized in that the method comprises the steps of:
step 1, preparation of periclase-spinel ceramic fine powder
Step 1.1, heating the fine aluminum hydroxide powder to 320-400 ℃ at the speed of 2-5 ℃/min, preserving the heat for 1-3 h, and cooling to obtain the fine porous aluminum oxide powder with high porosity;
step 1.2, taking 10-40 wt% of the high-porosity porous alumina fine powder and 60-90 wt% of light-burned magnesite fine powder as raw materials, placing the raw materials in a stirrer, and stirring for 1-3 hours; adding 3-6 wt% of alumina sol of the raw material, and mixing for 10-20 min to obtain a mixture;
step 1.3, performing mechanical pressing molding on the mixture under the condition of 100-150 MPa, and drying a molded blank at the temperature of 110 ℃ for 24-48 h; then heating to 1600-1750 ℃ at the speed of 4-5 ℃/min, preserving the heat for 2-6 h, and cooling to obtain the micro-nano-aperture periclase-spinel ceramic;
the periclase-spinel ceramic with the micro-nano aperture comprises: an apparent porosity of 24 to 32% and a bulk density of 2.42 to 2.71g/cm3The average pore diameter of the pores is 600-1550 nm;
step 1.4, crushing and screening the micro-nano-aperture periclase-spinel ceramic to obtain micro-nano-aperture periclase-spinel ceramic fine powder, wherein the particle size of the micro-nano-aperture periclase-spinel ceramic fine powder is less than 30 microns;
step 2, preparation of modified periclase-spinel ceramic fine powder
Step 2.1, placing the deionized water and the ferric nitrate nonahydrate into a stirrer according to the mass ratio of the deionized water to the ferric nitrate nonahydrate of 100: 1.5-5.5, and stirring for 10-20 min to obtain a modified solution;
step 2.2, placing the fine powder of the periclase-spinel ceramic with the micro-nano aperture in a vacuum device according to the mass ratio of the fine powder of the periclase-spinel ceramic to the modified solution of 100: 20-36, vacuumizing to 2.0-3.0 kPa, adding the modified solution, stirring for 15-30 min, closing a vacuumizing system, and naturally drying for 24-32 h to obtain the fine powder of the modified periclase-spinel ceramic;
step 3, preparation of pretreated polyurethane foam
Soaking 8-20 ppi polyurethane foam in NaOH solution for 2-4 h, taking out, washing with deionized water for 2-6 times, and airing to obtain pretreated polyurethane foam;
step 4, preparation of silicon nitride whisker reinforced periclase-spinel-carbon filter
Taking 75-85 wt% of modified periclase-spinel ceramic fine powder, 7-11 wt% of magnesite fine powder, 3-7 wt% of modified coal tar asphalt powder, 2.5-5 wt% of simple substance silicon powder and 0.5-3 wt% of sodium carboxymethyl cellulose as raw materials, placing the raw materials into a mixer, mixing for 2-5 h, adding 2-5 wt% of alumina sol, 0.04-0.15 wt% of water reducing agent, 0.3-1.3 wt% of defoaming agent and 20-35 wt% of deionized water as the raw materials, and stirring for 40-60 min to obtain ceramic slurry with thixotropy;
immersing the pretreated polyurethane foam into the thixotropic ceramic slurry for 10-15 min, taking out, removing redundant ceramic slurry by using a pair roller machine, curing for 15-26 h at room temperature, and drying for 12-24 h at 80-110 ℃; then in N2Partial pressure of 1atm, O2Partial pressure of less than 1.0X 10-14.4Pa and CO partial pressure less than 1.0X 10-6.4Heating to 1200-1300 ℃ at the speed of 0.5-2 ℃/min under the atmosphere condition of Pa, preserving heat for 2-4 h, and cooling to obtain a periclase-spinel-carbon filter pre-sintered body;
dipping the periclase-spinel-carbon filter pre-sintered body into the ceramic slurry with thixotropy for 10-20 minutes, taking out, and then treating in a centrifuge at a rotating speed of 200-450 r/min for 3-5 minutes to obtain a secondary slurry coated periclase-spinel-carbon filter blank; naturally drying the secondary slurry coating periclase-spinel-carbon filter blank for 20-40 h, drying at 80-110 ℃ for 12-36 h, and then drying in N2Partial pressure of 1atm, O2Partial pressure of less than 1.0X 10- 14.4Pa and CO partial pressure less than 1.0X 10-6.4Heating to 1300-1400 ℃ at the speed of 2-6 ℃/min under the atmosphere condition of Pa, preserving heat for 3-6 h, and cooling to obtain the silicon nitride whisker reinforced periclase-spinel-carbon filter;
the water reducing agent is sodium lignosulphonate or polycarboxylate; the content of lignin in the sodium lignosulphonate is 45-60 wt%, and the molecular weight of a side chain in the polycarboxylate is 700-2300.
2. The method of making a silicon nitride whisker reinforced periclase-spinel-carbon filter as claimed in claim 1, characterized in that the particle size of the aluminum hydroxide fine powder is less than 44 μm; al of the aluminum hydroxide fine powder2O3The content is 64-66 wt%.
3. A method of making a silicon nitride whisker reinforced periclase-spinel-carbon filter according to claim 1, characterized in that the particle size of the soft-burned magnesite fines is less than 44 μ ι η; the MgO content of the light-burned magnesite fine powder is more than 95 wt%.
4. The method of making a silicon nitride whisker reinforced periclase-spinel-carbon filter according to claim 1, characterized in that the aluminum sol of step 1.2 and the aluminum sol of step 4 are the same; al of the aluminum sol2O3The content is 20-45 wt%.
5. Method for the preparation of a silicon nitride whisker reinforced periclase-spinel-carbon filter according to claim 1, characterized in that the Fe (NO) of iron nitrate nonahydrate3)3·9H2The O content is more than 98 wt%.
6. The method for making a silicon nitride whisker reinforced periclase-spinel-carbon filter according to claim 1, characterized in that the solvent of the NaOH solution is deionized water; the concentration of the NaOH solution is 6-8 mol/L.
7. The method of making a silicon nitride whisker reinforced periclase-spinel-carbon filter according to claim 1, characterized in that the magnesia fine powder has a particle size of less than 44 μm; the MgO content of the magnesite fine powder is more than 96 wt%.
8. The method for preparing a silicon nitride whisker reinforced periclase-spinel-carbon filter according to claim 1, characterized in that the particle size of the modified coal tar pitch powder is less than 74 μm; the C content of the modified coal tar asphalt powder is more than 70 wt%.
9. The method for preparing a silicon nitride whisker reinforced periclase-spinel-carbon filter according to claim 1, wherein the particle size of the elemental silicon powder is less than 45 μm; the Si content of the elemental silicon powder is more than 98 wt%.
10. A silicon nitride whisker reinforced periclase-spinel-carbon filter characterized in that the silicon nitride whisker reinforced periclase-spinel-carbon filter is a silicon nitride whisker reinforced periclase-spinel-carbon filter prepared according to the method for preparing a silicon nitride whisker reinforced periclase-spinel-carbon filter according to any one of claims 1 to 9.
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