Method for preparing microporous semicircular tube type silicon carbide sintering kiln furniture

Abstract

The invention discloses a method for preparing microporous semicircular tube type silicon carbide sintering kiln furniture, which comprises the following specific steps: 1, mixing silicon carbide aggregate, a pore forming agent and a sintering aid in proportion to obtain a dry mixed material sample; 2, fully wet-mixing the dry-mixed material sample with a binder to obtain a wet-mixed material sample, and screening to obtain a granulation sample; and 3, filling the granulated sample into a mold, and carrying out vibration fluidization, isostatic compaction and demolding to obtain a tubular silicon carbide green body. And 4, placing the tubular silicon carbide green body in a kiln for reaction sintering to obtain the tubular silicon carbide. And 5, segmenting the tubular silicon carbide by laser cutting to prepare the microporous semicircular tubular silicon carbide sintering kiln furniture. The microporous semicircular tube type silicon carbide sintering kiln furniture prepared by the invention is high in high-temperature strength and strong in permeability, not only can play a role in bearing, but also is beneficial to atmosphere flow in a furnace, and the heat efficiency is improved; meanwhile, the kiln furniture is small in expansion rate, high in thermal shock resistance and suitable for the sintering process of various tubular ceramic green high-temperature intermittent kilns and high-temperature continuous kilns.

Description

Technical Field

[0001] The present invention relates to high-temperature sintering kiln furniture, and particularly to a method for preparing a microporous semi-circular tube-shaped silicon carbide sintering kiln furniture. Background Art

[0002] Sintering kiln furniture plays a crucial role in the ceramic production process. First, it spaces and supports the green bodies to be sintered, preventing the green bodies from contacting each other and causing adhesion or damage. Second, it pads and protects the green bodies, avoiding the green bodies from contacting the bottom of the kiln or other components and causing contamination or damage. Third, it facilitates handling and use, helping to improve production efficiency. Fourth, the reasonable design and use of kiln furniture can promote the uniform distribution and precise control of the temperature in the furnace, thereby improving the quality and performance of the sintered products.

[0003] Currently, most of the tube-shaped sintering kiln furniture on the market are made of dense materials, with poor gas permeability, low high-temperature strength, poor thermal shock resistance, and a service life of only 4 - 8 months. Therefore, the present invention uses large-particle silicon carbide and prepares a microporous semi-circular tube-shaped silicon carbide sintering kiln furniture with good gas permeability, high high-temperature strength, and high thermal shock resistance through a special process. Summary of the Invention

[0004] The purpose of the present invention is to provide a method for preparing a microporous semi-circular tube-shaped silicon carbide sintering kiln furniture, so as to solve the problems of low gas permeability, low high-temperature strength, and poor high-temperature thermal shock resistance of the sintering kiln furniture.

[0005] The technical solution of the present invention is as follows: A method for preparing a microporous semi-circular tube-shaped silicon carbide sintering kiln furniture, the preparation steps are as follows: (1) Select large-particle silicon carbide as the aggregate, and mix it with a pore-forming agent and a sintering aid in proportion to obtain a dry-mixed material sample; (2) Thoroughly wet-mix the above dry-mixed material sample with the atomized binder to obtain a wet-mixed material sample. Then, perform a classification screening process on the wet-mixed material sample to obtain a granulated sample with uniform particle size; (3) Fill the granulated sample into a molding die, and through vibration fluidization, make the material distribution more uniform, and then put it into an isostatic pressing forming device for forming operation.

[0006] (4) After forming, dry and demold to obtain a tube-shaped silicon carbide green body; (5) Place the tube-shaped silicon carbide green body in a sintering furnace and sinter it according to a preset program to finally obtain a microporous tube-shaped silicon carbide; (6) Use laser cutting technology to cut and divide the microporous tube-shaped silicon carbide to obtain the required microporous semi-circular tube-shaped silicon carbide sintering kiln furniture.

[0007] Among them: the particle size of the large-particle silicon carbide in step (1) is 50 - 500 µm, the pore-forming agent is one or more of carbon powder, starch, graphite, ammonium carbonate, etc.; the sintering aid is one or more of nano zirconia, alumina, calcium oxide, magnesium oxide, mullite powder, etc.; the mass ratio of the large-particle silicon carbide to the pore-forming agent is 7:3 - 9:1, and the mass ratio of the large-particle silicon carbide to the sintering aid is 70:3 - 90:1.

[0008] The dry mixing in step (1) is carried out using one of a dry ball mill, a planetary ball mill, and a three-dimensional motion mixer; the mixing time is 1 - 12 h, and the mixing rate is 10 - 500 r / min.

[0009] The mass ratio of the dry-mixed material sample to the atomized binder in step (2) is 40:1 - 10:1.

[0010] The vibration fluidization frequency in step (3) is 20 - 60 times / min, and the vibration time is 5 - 30 min.

[0011] The forming operation pressure in step (3) is 50 - 150 Mpa, and the pressure holding time is 5 - 15 min.

[0012] The drying temperature in step (4) is 40 - 80 °C, and the drying time is 2 - 6 h.

[0013] The preset program in step (5) is: first heat up to 1200 - 1550 °C, keep it warm in the air atmosphere for 0.5 - 4 h, and then cool down naturally; the heating rate is 2 - 10 °C / min.

[0014] For the microporous semi-circular tube-shaped silicon carbide sintering kiln furniture described above, the gas permeability can reach 12×10 4 -30×10 4 m 3 / (m 2 ·h·bar), and the flexural strength is 12 - 40 MPa.

[0015] The beneficial effects of the present invention: 1. The silicon carbide sintering kiln prepared by the present invention has ultra-high gas permeability and good flexural strength. Due to the microporosity of silicon carbide, it has a large specific surface area, so it can efficiently convert the sensible heat of the gas flow into solid radiant heat. Under the influence of radiation, the temperature distribution in the sintering furnace becomes more and more uniform, and the temperature gradient gradually decreases, improving the anti-temperature difference change ability of the silicon carbide sintering kiln furniture. It is applicable to the firing process of high-temperature ceramic products in different industries, especially applicable to the firing process of ceramic membrane tubes in industries such as gas purification and water treatment.

[0016] 2. The preparation process of the present invention is simple, easy to operate, and convenient for industrial production. Brief Description of the Drawings

[0017] Figure 1 Physical diagram of the kiln furniture described in the present invention.

[0018] Figure 2 Microscopic cross-section diagram of the kiln furniture described in the present invention. Detailed Description of the Invention

[0019] The present invention will be further explained below in conjunction with the embodiments. The following embodiments are only used to illustrate the present invention, but not to limit the scope of implementation of the present invention. Embodiment 1

[0020] Silicon carbide with a particle size of 50 μm, pore-forming agents (carbon powder and mullite fiber), and sintering aids (nano-zirconia and magnesium oxide) are uniformly mixed in a mass ratio of 7:2:1 by mechanical stirring. The stirring time is 12 h and the stirring speed is 100 r / min to obtain a dry-mixed sample; then the dry-mixed sample is mixed with the atomized binder in a ratio of 20:1 to obtain a wet-mixed sample. Then, the wet-mixed sample is screened to obtain a granulated sample, and the granulated sample is filled into a molding die. After vibration fluidization with a frequency of 20 times / min and a vibration time of 30 min, it is then put into an isostatic pressing forming device for forming operation. The operation pressure is 50 Mpa and the pressure holding time is 15 min. After forming, it is dried at a constant temperature of 40 °C for 6 h and then demolded to obtain a tubular silicon carbide green body; then the tubular silicon carbide green body is put into a sintering furnace. First, it is heated up to 1200 °C in a programmed manner, held in an air atmosphere for 4 h, and then cooled naturally. The heating rate is 2 °C / min; finally, laser cutting technology is used to cut and divide the microporous tubular silicon carbide to obtain a microporous semi-circular tubular silicon carbide sintered kiln furniture.

[0021] After testing, the obtained microporous semi-circular tubular silicon carbide sintered kiln furniture has an N2 gas permeation flux of 12.9×10 4 m 3 / m 2 ·h·bar, a flexural strength of 37.8 MPa, and after 20 air-cooling cycles at 0 - 800 °C, the strength decrease is less than 10%. Embodiment 2

[0022] Silicon carbide with a particle size of 200 μm is uniformly mixed with pore formers (carbon powder and mullite fiber) and sintering aids (nano zirconia and magnesium oxide) in a mass ratio of 7:3:3 by mechanical stirring for 6 h at a stirring speed of 200 r / min to obtain a dry mixed sample; then the dry mixed sample is mixed with the atomized binder in a ratio of 10:1 to obtain a wet mixed sample, and then the wet mixed sample is screened to obtain a granulated sample. The granulated sample is filled into a molding die and subjected to vibration fluidization at a frequency of 30 times / min and a vibration time of 20 min, and then put into an isostatic pressing molding equipment for molding operation. The operation pressure is 150 Mpa and the pressure holding time is 5 min. After molding, it is dried at a constant temperature of 80 °C for 2 h and then demolded to obtain a tubular silicon carbide green body; then the tubular silicon carbide green body is put into a sintering furnace, first heated to 1550 °C at a programmed heating rate, held for 0.5 h in an air atmosphere, and then cooled naturally. The heating rate is 4 °C / min; finally, the microporous tubular silicon carbide is cut and segmented by laser cutting technology to obtain a microporous semi-circular tubular silicon carbide sintering kiln furniture.

[0023] After testing, the obtained microporous semi-circular tubular silicon carbide sintering kiln furniture has an N2 gas permeation flux of 14.6×10 4 m 3 / m 2 ·h·bar, a flexural strength of 32.2 MPa, and after 20 air-cooling cycles at 0 - 800 °C, the strength decrease is less than 10%. Example 3

[0024] Silicon carbide with a particle size of 300 μm is uniformly mixed with pore formers (carbon powder and mullite fiber) and sintering aids (nano zirconia and magnesium oxide) in a mass ratio of 8:2:1 by mechanical stirring for 4 h at a stirring speed of 300 r / min to obtain a dry mixed sample; then the dry mixed sample is mixed with the atomized binder in a ratio of 20:1 to obtain a wet mixed sample, and then the wet mixed sample is screened to obtain a granulated sample. The granulated sample is filled into a molding die and subjected to vibration fluidization at a frequency of 40 times / min and a vibration time of 20 min, and then put into an isostatic pressing molding equipment for molding operation. The operation pressure is 80 Mpa and the pressure holding time is 10 min. After molding, it is dried at a constant temperature of 50 °C for 4 h and then demolded to obtain a tubular silicon carbide green body; then the tubular silicon carbide green body is put into a sintering furnace, first heated to 1300 °C at a programmed heating rate, held for 3 h in an air atmosphere, and then cooled naturally. The heating rate is 6 °C / min; finally, the microporous tubular silicon carbide is cut and segmented by laser cutting technology to obtain a microporous semi-circular tubular silicon carbide sintering kiln furniture.

[0025] After testing, the obtained microporous semi-circular tubular silicon carbide sintering kiln furniture has an N2 gas permeation flux of 18.5×10 4 m 3 / m2 ·h·bar, the flexural strength is 29.3 MPa. After 20 air-cooling cycles at 0 - 800 °C, the strength reduction is less than 10%. Example 4

[0026] Silicon carbide with a particle size of 400 μm was uniformly mixed with pore-forming agents (carbon powder and mullite fiber) and sintering aids (nano-zirconia and magnesium oxide) in a mass ratio of 8:1:1 by mechanical stirring for 3 h at a stirring speed of 400 r / min to obtain a dry-mixed sample. Then, the dry-mixed sample was mixed with the atomized binder in a ratio of 30:1 to obtain a wet-mixed sample. Then, the wet-mixed sample was screened to obtain a granulated sample. Then, the granulated sample was loaded into a molding die and subjected to vibration fluidization with a frequency of 50 times / min and a vibration time of 10 min. Then, it was put into an isostatic pressing molding device for molding operation with an operating pressure of 120 Mpa and a pressure holding time of 8 min. After molding, it was dried at a constant temperature of 60 °C for 3 h and then demolded to obtain a tubular silicon carbide green body. Then, the tubular silicon carbide green body was put into a sintering furnace, first heated to 1400 °C at a programmed heating rate, held for 1 h in an air atmosphere, and then cooled naturally with a heating rate of 8 °C / min. Finally, the microporous tubular silicon carbide was cut and segmented by laser cutting technology to obtain a microporous semi-circular tubular silicon carbide sintering kiln furniture.

[0027] After testing, for the obtained microporous semi-circular tubular silicon carbide sintering kiln furniture, the N2 gas permeation flux is 23.4×10 4 m 3 / m 2 ·h·bar, the flexural strength is 24.1 MPa. After 20 air-cooling cycles at 0 - 800 °C, the strength reduction is less than 10%. Example 5

[0028] Silicon carbide with a particle size of 500 μm is uniformly mixed with pore-forming agents (carbon powder and mullite fiber) and sintering aids (nano-zirconia and magnesia) in a mass ratio of 9:1:1 by mechanical stirring for 1 h at a stirring speed of 500 r / min to obtain a dry-mixed sample; then the dry-mixed sample is mixed with the atomized binder in a ratio of 40:1 to obtain a wet-mixed sample, and then the wet-mixed sample is screened to obtain a granulated sample. The granulated sample is filled into a molding die and subjected to vibration fluidization with a frequency of 60 times / min and a vibration time of 5 min, and then placed in an isostatic pressing equipment for molding operation with an operating pressure of 50 Mpa and a pressure holding time of 10 min. After molding, it is dried at a constant temperature of 70 °C for 2 h and then demolded to obtain a tubular silicon carbide green body; then the tubular silicon carbide green body is placed in a sintering furnace, first heated to 1400 °C at a programmed rate, held in an air atmosphere for 0.5 h, and then cooled naturally with a heating rate of 10 °C / min; finally, the microporous tubular silicon carbide is cut and segmented by laser cutting technology to obtain a microporous semi-circular tubular silicon carbide sintering kiln furniture.

[0029] After testing, the obtained microporous semi-circular tubular silicon carbide sintering kiln furniture has an N2 gas permeation flux of 29.6×10 4 m 3 / m 2 ·h·bar, a flexural strength of 13.8 MPa, and the strength decreases by less than 10% after 20 air-cooling cycles at 0-800 °C.

Claims

1. A method for preparing a microporous semi-circular tubular silicon carbide sintering kiln furniture, characterized in that, The preparation steps are as follows: (1)Select large-particle silicon carbide as the aggregate, mix it with a pore-forming agent and a sintering aid in proportion, and then perform dry mixing operation to obtain a dry-mixed sample; (2)Fully wet-mix the above dry-mixed sample with the atomized binder to obtain a wet-mixed sample; then carry out classification screening on the wet-mixed sample to obtain a granulated sample with uniform particle size; (3)Load the granulated sample into a molding die, and through vibration fluidization, make the material distribution more uniform, and then put it into an isostatic pressing molding equipment for molding operation; (4)After molding, place it in an oven for constant-temperature drying, demold after drying to obtain a tubular silicon carbide green body; (5)Place the tubular silicon carbide green body in a high-temperature sintering furnace for sintering to obtain microporous tubular silicon carbide; (6)Use laser cutting technology to cut the microporous tubular silicon carbide to obtain the required microporous semi-circular tubular silicon carbide sintering kiln furniture.

2. The method for preparing a microporous semi-circular tubular silicon carbide sintering kiln furniture according to claim 1, characterized in that, In step (1), the particle size of the large-particle silicon carbide is 50-500 µm, the pore-forming agent is one or more of carbon powder, starch, graphite, ammonium carbonate, and the sintering aid is one or more of nano zirconia, alumina, calcium oxide, magnesium oxide, mullite powder; the mass ratio of the large-particle silicon carbide to the pore-forming agent is 7:3-9:1, and the mass ratio of the large-particle silicon carbide to the sintering aid is 70:3-90:

1.

3. The method for preparing a microporous semi-circular tubular silicon carbide sintering kiln furniture according to claim 1, characterized in that, In step (1), the dry mixing is carried out using one of a dry ball mill, a planetary ball mill, and a three-dimensional motion mixer; the mixing time is 1-12 h, and the mixing rate is 10-500 r / min.

4. A method for preparing a microporous semi-circular tubular silicon carbide sintering kiln furniture according to claim 1, characterized in that, In step (2), the mass ratio of the dry-mixed sample to the atomized binder is 40:1-10:

1.

5. A method for preparing a microporous semi-circular tubular silicon carbide sintering kiln furniture according to claim 1, characterized in that, In step (3), the vibration fluidization frequency is 20-60 times / min, and the vibration time is 5-30 min.

6. The method for preparing a microporous semi-circular tube-shaped silicon carbide sintering kiln furniture according to claim 1, characterized in that, In step (3), the molding operation pressure is 50-150 Mpa, and the pressure holding time is 5-15 min.

7. The method for preparing a microporous semi-circular tubular silicon carbide sintering kiln furniture according to claim 1, wherein In step (4), the drying temperature is 40-80 °C, and the drying time is 2-6 h.

8. The method for preparing a microporous semi-circular tubular silicon carbide sintering kiln furniture according to claim 1, wherein, In step (5), the sintering procedure is: first heat up to 1200-1550 °C, keep it warm in an air atmosphere for 0.5-4 h, and then cool down naturally; the heating rate is 2-10 °C / min.

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