A method for preparing a high-corrosion-resistant porous silicon carbide ceramic membrane support and a product prepared thereby

Abstract

The application discloses a preparation method of a high-corrosion-resistance silicon carbide porous ceramic membrane support and a product prepared by the method. The silicon carbide porous ceramic membrane support is prepared by taking silicon carbide powder as an aggregate, taking alumina and titanium dioxide as sintering aids, and taking walnut shell powder as a pore-forming agent. The silicon carbide porous ceramic membrane support has high bending strength, high porosity and excellent corrosion resistance, and is suitable for application in the fields of wastewater treatment and high-temperature waste gas treatment. The preparation method is simple in operation, saves resources, is low in cost, has low energy consumption, and is easy for industrialized production.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of functional material preparation, and particularly relates to a preparation method of a high-corrosion-resistant silicon carbide porous ceramic membrane support and a product prepared by the method. BACKGROUND

[0002] With the acceleration of global urbanization and frequent industrial activities, the discharge of a large amount of waste gas, domestic sewage and industrial wastewater with complex components has seriously damaged the ecological balance and species diversity, and environmental pollution has become a global crisis. In order to reduce environmental pollution and save resources, it is an urgent need for human beings to develop low-cost, energy-saving, environmentally friendly and environment-friendly purification technology. Ceramic filtration materials have excellent chemical stability, thermal stability, pollution resistance, high mechanical strength, easy cleaning, high filtration efficiency, long service life and the like, and have attracted extensive attention of researchers in the fields of high-temperature gas purification, water treatment, biological fermentation and the like. The main raw materials of the ceramic membrane commonly used in the prior art are ceramic materials such as alumina, silicon oxide and zirconium oxide, which have the characteristics of amphoteric oxides, acidic oxides or basic oxides, but when used in some harsh media (such as high temperature and strong acid and alkali), the existing ceramic membrane often has a serious decrease in strength or even breaks, and has the disadvantages of easy clogging and difficult cleaning, easy corrosion (such as alkali liquid cleaning), high brittleness and easy breaking after long-term corrosion impact, and the like, so that the wide use of the ceramic membrane in many fields brings challenges.

[0003] SiC is a compound with very strong covalent bond, and the bond length of Si-C bond is Si and C are combined into SiC4 and CSi4 coordination tetrahedrons through Si-C bond. The SiC4 and CSi4 coordination tetrahedrons form a typical covalent bond compound with diamond structure through SP 3 Hybridization. Silicon carbide porous ceramic has excellent mechanical properties, excellent oxidation resistance, high wear resistance, low friction coefficient, excellent corrosion resistance and the like, and becomes one of the best choices for filtration materials. The commercial SiC ceramic membrane is mainly sintered at a high temperature of 2100 DEG C or above in an inert atmosphere by a recrystallization sintering process, which has high energy consumption, complicated preparation and high production cost, which is contrary to the low-cost concept required for wastewater and waste gas treatment. Therefore, it is crucial to develop a low-energy-consumption, low-cost and high-performance SiC ceramic membrane preparation method. SiC is easy to be oxidized to form SiO2 when in contact with air during sintering, and is not only easy to react with strong alkali solution at room temperature, but also easy to be corroded by sulfur oxides, nitrogen oxides, water vapor and alkali metal compounds under high temperature conditions, which seriously affects the thermal shock resistance and corrosion resistance of the silicon carbide ceramic membrane. Therefore, the oxidation of silicon carbide material is a key problem for the preparation of silicon carbide ceramic membrane, and how to effectively improve the mechanical properties and corrosion resistance of silicon carbide material is a problem to be solved at present and has important research and application value. SUMMARY

[0004] The present application aims to overcome the deficiencies of the prior art, and provides a preparation method of a high-corrosion-resistant silicon carbide porous ceramic membrane support body, which uses silicon carbide powder as aggregate, alumina and titanium dioxide as sintering aids, and walnut shell powder as a pore-forming agent, and forms mullite crystals in situ to enhance the neck bonding between silicon carbide particles, thereby improving the mechanical properties, water flux, and corrosion resistance of the material. Another object of the present application is to provide a product prepared by the above method.

[0005] The object of the present application is achieved by the following technical solutions:

[0006] The present application provides a preparation method of a high-corrosion-resistant silicon carbide porous ceramic membrane support body, which comprises the following steps:

[0007] (1) mixing silicon carbide powder as aggregate, alumina and titanium dioxide as sintering aids, and walnut shell powder as a pore-forming agent according to the mass ratio of silicon carbide powder: alumina: titanium dioxide: walnut shell powder = 70-87: 5-18: 8-12: 10-15, and then ball milling, aging, and drying to obtain a mixed powder;

[0008] (2) granulating and dry pressing the mixed powder to obtain a silicon carbide membrane support body green body after drying;

[0009] (3) sintering the silicon carbide membrane support body green body to obtain a high-corrosion-resistant silicon carbide porous ceramic membrane support body.

[0010] Further, the silicon carbide powder of the present application is composed of coarse silicon carbide powder with a particle size of D50 = 80-150 μm and fine particle size silicon carbide with a particle size of D50 = 26-35 μm; the walnut shell powder has a particle size of D50 = 30-80 μm. In step (1), the material: ball: water is 1: 1-2: 1, and ball milling is performed for 50-60 min, then 1-5 wt% polyethylene aqueous solution is added and ball milling is performed for 20-30 min, and the amount of polyethylene aqueous solution is 5-10 wt% of the mixed material; the aging time is 12-36 h. The drying temperature in steps (1) and (2) is 80-110℃, and the drying time is 2-24 h.

[0011] Further, the sintering schedule of step (3) of the present application is to heat from room temperature to 600-800℃ at 2℃ / min, keep for 100-120 min, then increase the temperature to 1150-1300℃ at 5℃ / min, keep for 110-140 min, and then naturally cool to room temperature in the furnace.

[0012] Another object of the present application is achieved by the following technical solutions:

[0013] The product prepared by the preparation method of the high corrosion-resistant silicon carbide porous ceramic membrane support provided by the application has a skeleton of silicon carbide particles, and mainly has silicon dioxide and mullite crystals at the neck bonding sites between the silicon carbide particles. The bending strength of the ceramic membrane support is 36-73 MPa, the porosity is 28-33%, the average pore size is 1.67-5.32 μm, the water flux is 0.7508-1.897 x 10 -6 L·m -2 ·h -1 ·bar -1 ; after corrosion in a 20% sulfuric acid solution at 90°C for 1 h, the bending strength is 84%-108% of the original bending strength, and after corrosion in a 1% sodium hydroxide solution at 90°C for 1 h, the bending strength is 94-103% of the original bending strength.

[0014] The application has the following beneficial effects:

[0015] (1) The silicon carbide porous ceramic membrane support prepared by the application has high mechanical strength, large water flux, excellent corrosion resistance and the like. In the sintering process, titanium dioxide and aluminum oxide are used as nucleating agents and sintering aids, and in-situ mullite crystals are formed with silicon dioxide to combine with silicon carbide to form a porous ceramic support, thereby enhancing the neck bonding between the silicon carbide particles and significantly improving the mechanical properties and corrosion resistance of the material. The flow and migration of the SiO2 film layer in the liquid phase at high temperature make the support porosity well connected, thereby improving the water flux.

[0016] (2) The application uses aluminum oxide and titanium dioxide as sintering aids and uses waste walnut shell powder as a pore-forming agent to prepare a high corrosion-resistant silicon carbide porous ceramic membrane support by an in-situ reaction sintering method, and has the advantages of simple operation, resource saving, low cost, low energy consumption and easy industrial production, and has a wide application prospect and is suitable for wastewater treatment, high-temperature waste gas filtration and the like. BRIEF DESCRIPTION OF DRAWINGS

[0017] The application will be further described in detail below with reference to the embodiments and the drawings:

[0018] Figure 1 is an XRD pattern of the silicon carbide porous ceramic membrane support prepared in the embodiment of the application;

[0019] Figure 2 is an SEM image (a: 500 times; b: 5000 times) of the silicon carbide porous ceramic membrane support prepared in the embodiment of the application;

[0020] Figure 3 is a pore size distribution graph of the silicon carbide porous ceramic membrane support prepared in the second embodiment of the application;

[0021] Figure 4 The flexural strength of the silicon carbide porous ceramic membrane support prepared in Example 1 of this invention after corrosion by a 20% sulfuric acid solution at 90°C is measured.

[0022] Figure 5 The flexural strength of the silicon carbide porous ceramic membrane support prepared in Example 1 of this invention after corrosion by a 1% sodium hydroxide solution at 90°C is measured. Detailed Implementation

[0023] Example 1:

[0024] This embodiment describes a method for preparing a highly corrosion-resistant porous silicon carbide ceramic membrane support, the steps of which are as follows:

[0025] (1) Using silicon carbide powder (coarse silicon carbide powder with a particle size of D50 = 80-150 μm and fine silicon carbide powder with a particle size of D50 = 26-35 μm) as aggregate, alumina and titanium dioxide as sintering aids, and walnut shell powder with a particle size of D50 = 30-80 μm as pore-forming agent, the mixture was prepared by mixing coarse silicon carbide powder: fine silicon carbide alumina: titanium dioxide: walnut shell powder = 49:21:18:12:15 by mass. The mixture was ball-milled at 516 r / min for 60 min according to the ratio of material:ball:water = 1:2:1. Then, a 5% polyethylene aqueous solution was added and the mixture was ball-milled for another 30 min. The amount of polyethylene aqueous solution was 5 wt% of the mixture. The resulting slurry was aged for 12 h and then dried at 110℃ for 2 h to obtain the mixed powder.

[0026] (2) The above mixed powder is granulated, dry-pressed under 12MPa pressure, and dried at 110℃ for 2h to obtain a silicon carbide film support green body with a certain strength.

[0027] (3) The above-mentioned silicon carbide film support green body is transferred to an electric furnace for sintering treatment. The sintering process is as follows: heat from room temperature to 600℃ at 2℃ / min, hold for 120min, then heat to 1300℃ at 5℃ / min, hold for 120min, and then cool naturally to room temperature with the furnace to obtain a highly corrosion-resistant silicon carbide porous ceramic film support.

[0028] Example 2:

[0029] This embodiment describes a method for preparing a highly corrosion-resistant porous silicon carbide ceramic membrane support, the steps of which are as follows:

[0030] (1) Fine silicon carbide powder with particle size D50 = 26-35 μm as aggregate, alumina, titanium dioxide as sintering aids, walnut shell powder with particle size D50 = 30-80 μm as pore-forming agent, the mixture obtained by mixing fine particle size silicon carbide alumina: titanium dioxide: walnut shell powder = 80: 12: 8: 10 (mass ratio), ball milling for 60 min at a speed of 516 r / min, then adding 5% polyethylene aqueous solution, continue ball milling for 30 min, the amount of polyethylene aqueous solution is 5% of the mixture, the obtained mixed slurry is aged for 36 h, then dried at 90℃ for 12 h, to obtain a mixed powder;

[0031] (2) The above mixed powder is granulated, dry pressed at a pressure of 12 MPa, and dried at a temperature of 110℃ for 2 h to obtain a green body of silicon carbide membrane support with certain strength;

[0032] (3) The above green body of silicon carbide membrane support is moved to an electric furnace for sintering treatment, the sintering schedule is: heating from room temperature to 800℃ at a rate of 2℃ / min, keeping for 100 min, then heating to 1250℃ at a rate of 5℃ / min, keeping for 110 min, then naturally cooling to room temperature in the furnace, to obtain a high corrosion-resistant silicon carbide porous ceramic membrane support.

[0033] Example Three:

[0034] The preparation method of a high corrosion-resistant silicon carbide porous ceramic membrane support in this embodiment is as follows:

[0035] (1) Fine silicon carbide powder with particle size D50 = 26-35 μm as aggregate, alumina, titanium dioxide as sintering aids, walnut shell powder with particle size D50 = 30-80 μm as pore-forming agent, the mixture obtained by mixing fine particle size silicon carbide alumina: titanium dioxide: walnut shell powder = 87: 5: 8: 10 (mass ratio), ball milling for 60 min at a speed of 516 r / min, then adding 1% polyethylene aqueous solution, continue ball milling for 30 min, the amount of polyethylene aqueous solution is 10% of the mixture, the obtained mixed slurry is aged for 12 h, then dried at 110℃ for 2 h, to obtain a mixed powder;

[0036] (2) The above mixed powder is granulated, dry pressed at a pressure of 12 MPa, and dried at a temperature of 80℃ for 24 h to obtain a green body of silicon carbide membrane support with certain strength;

[0037] (3) The green body of the silicon carbide membrane support is moved to an electric furnace for sintering treatment, and the sintering system is as follows: heating from room temperature to 800℃ at a rate of 2℃ / min, keeping for 120min, then heating to 1250℃ at a rate of 5℃ / min, keeping for 120min, and then naturally cooling to room temperature in the furnace, to obtain the high-corrosion-resistant silicon carbide porous ceramic membrane support.

[0038] Example Four:

[0039] The preparation method of the high-corrosion-resistant silicon carbide porous ceramic membrane support in this embodiment is as follows:

[0040] (1) Fine silicon carbide powder with a particle size of D50=26-35μm is used as the aggregate, alumina and titanium dioxide are used as the sintering aids, walnut shell powder with a particle size of D50=30-80μm is used as the pore-forming agent, and the mixture obtained by mixing the fine particle size silicon carbide, alumina, titanium dioxide and walnut shell powder in a mass ratio of 80:12:8:10 is ball milled at a speed of 516r / min for 50min, and then 3% polyethylene aqueous solution is added for further ball milling for 40min, the amount of the polyethylene aqueous solution is 7wt% of the mixture, the obtained mixed slurry is aged for 12h, and then dried at a temperature of 90℃ for 24h to obtain the mixed powder;

[0041] (2) The mixed powder is granulated and dry-pressed into a silicon carbide membrane support green body under a pressure of 12MPa and dried at a temperature of 110℃ for 2h;

[0042] (3) The silicon carbide membrane support green body is moved to an electric furnace for sintering treatment, and the sintering system is as follows: heating from room temperature to 800℃ at a rate of 2℃ / min, keeping for 120min, then heating to 1150℃ at a rate of 5℃ / min, keeping for 140min, and then naturally cooling to room temperature in the furnace, to obtain the high-corrosion-resistant silicon carbide porous ceramic membrane support.

[0043] The performance indexes of the silicon carbide porous ceramic membrane support prepared in the embodiment of the present application are shown in Table 1.

[0044] Table 1 Performance indexes of the silicon carbide porous ceramic membrane support prepared in the embodiment of the present application

[0045]

[0046] * Acid corrosion resistance: the flexural strength of the material is tested after being corroded in a 20% sulfuric acid solution at 90℃ for 1h.

[0047] * Alkali corrosion resistance: the flexural strength of the material is tested after being corroded in a 1% sodium hydroxide solution at 90℃ for 1h.

[0048] The silicon carbide porous ceramic membrane support prepared by the embodiment of the present application is in-situ reacted with silicon dioxide to form mullite crystals (see Figure 1 ) after adding alumina and titanium dioxide sintering aids, and the sintering aids are distributed in the necks of the silicon carbide particles, and the silicon carbide particles are broken through the crystals (see Figure 2 ), and the crystal phase in the necks mainly includes silicon dioxide and mullite crystals, thus having strong adhesion.

[0049] As shown in Figure 3 , the average pore diameter of the silicon carbide porous ceramic membrane support prepared by the second embodiment of the present application is 3.262 μm.

[0050] As shown in Figure 4 , the silicon carbide porous ceramic membrane support prepared by the first embodiment of the present application still maintains 90% of the original bending strength after being boiled in 20% sulfuric acid solution for 100 h, and has stable acid corrosion resistance.

[0051] As shown in Figure 5 , the silicon carbide porous ceramic membrane support prepared by the first embodiment of the present application has higher bending strength than the initial bending strength after being boiled in 1% sodium hydroxide solution for 100 h, and has excellent alkali corrosion resistance.

Claims

1. A method for producing a high corrosion-resistant porous silicon carbide ceramic membrane support, characterized by The method comprises the following steps: (1) mixing silicon carbide powder, alumina, titanium dioxide and walnut shell powder according to the mass ratio of silicon carbide powder: alumina: titanium dioxide: walnut shell powder = 70-87: 5-18: 8-12: 10-15, ball milling, aging and drying to obtain a mixed powder; the silicon carbide powder is composed of coarse silicon carbide powder with a particle size of D50 = 80-150 μm and fine silicon carbide powder with a particle size of D50 = 26-35 μm, and the walnut shell powder has a particle size of D50 = 30-80 μm; (2) granulating and dry-pressing the mixed powder, and drying to obtain a green body of a silicon carbide membrane support; (3) sintering the green body of the silicon carbide membrane support, and the sintering system is as follows: heating from room temperature to 600-800 ℃ at a rate of 2 ℃ / min, keeping the temperature for 100-120 min, then increasing the temperature to 1150-1300 ℃ at a rate of 5 ℃ / min, keeping the temperature for 110-140 min, and then naturally cooling to room temperature in the furnace, to obtain a high-corrosion-resistant porous silicon carbide ceramic membrane support.

2. The method of producing a high corrosion resistant silicon carbide porous ceramic membrane support according to claim 1, characterized by: In step (1), the mixture is ball milled for 50-60 min at a ratio of material: ball: water = 1: 1-2: 1, then 1-5 wt% polyethylene aqueous solution is added and ball milled for 20-30 min, and the amount of the polyethylene aqueous solution is 5-10 wt% of the mixture; the aging time is 12-36 h.

3. The method of producing a high corrosion resistant silicon carbide porous ceramic membrane support according to claim 1, characterized by: In steps (1) and (2), the drying temperature is 80-110 ℃, and the drying time is 2-24 h.

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