Preparation method of flour-toughened silicon carbide porous foamed ceramic
By mixing low-gluten flour with silicon carbide powder and using chemical reactions to generate silicon carbide, the problem of difficulty in preparing high-toughness silicon carbide foam ceramics in the prior art is solved, and high-efficiency preparation of high-toughness materials suitable for industrial production is achieved.
Patent Information
- Application Number
- CN202510409344.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-02
- Publication Date
- 2025-06-27
AI Technical Summary
The prior art is difficult to prepare highly tough silicon carbide foam ceramics, resulting in limited applications in the optical and electronic fields.
High toughness silicon carbide porous foam ceramics are prepared by using low-gluten flour as the reinforced phase precursor, mixed with silicon carbide powder, and chemical reaction between carbon and silicon source derived from low-gluten flour is prepared.
It realizes the effective preparation of high-tough silicon carbide porous foam ceramics, with a toughness of 10.56MPa·m1/2, and is suitable for large-scale industrial production.
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Figure CN120208694A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the field of silicon carbide ceramics. Background Art
[0002] Silicon carbide foam ceramics play an important role in the optical and electronic fields due to their excellent mechanical strength. Their high-strength characteristics can ensure the structural integrity and stability of the material as a high-performance substrate and radiator in extreme environments, not only extending the service life but also significantly improving the reliability of electronic components and optical devices under high temperature, high pressure, and other harsh conditions. Therefore, it has become an ideal choice for the support structure of optical lenses and high-efficiency heat dissipation materials. Currently, the main method for preparing high-strength silicon carbide foam is the polymer pre-impregnation method, that is, impregnating polyurethane sponge with silicon carbide slurry containing sintering aids and preparing it through high-temperature sintering. However, the introduction of sintering aids in this method will cause intergranular fracture between silicon carbide particles due to stress concentration, thus significantly reducing the toughness of the material and making it difficult to meet the strict requirements for material properties in the optical and electronic fields. In addition, there is currently no preparation method for high-toughness silicon carbide foam ceramics, which has become a key bottleneck restricting its wide application. Summary of the Invention
[0003] The present invention aims to solve the problem that high-toughness silicon carbide foam ceramics cannot be manufactured in the prior art, and further provides a preparation method for flour-toughened porous silicon carbide foam ceramics.
[0004] A preparation method for flour-toughened porous silicon carbide foam ceramics is carried out according to the following steps:
[0005] 1. Mix silicon carbide powder with low-gluten flour to obtain a silicon carbide / low-gluten flour mixed powder;
[0006] 2. Add deionized water to the silicon carbide / low-gluten flour mixed powder and disperse it evenly to obtain a silicon carbide / low-gluten flour slurry;
[0007] 3. At room temperature, immerse polyurethane sponge in the silicon carbide / low-gluten flour slurry, then take it out and use a roller press to extrude the excess slurry to obtain a silicon carbide / low-gluten flour / polyurethane block;
[0008] 4. Dry the silicon carbide / low-gluten flour / polyurethane block to obtain a silicon carbide / low-gluten flour / polyurethane preform;
[0009] 5. Carbonize the silicon carbide / low-gluten flour / polyurethane preform in a nitrogen atmosphere to obtain silicon carbide / carbon porous foam;
[0010] VI. Spread the waste silicon powder at the bottom of the graphite crucible, place the silicon carbide / carbon porous foam above the waste silicon powder, then tightly cover the crucible lid, and use boron nitride slurry to seal the gap between the graphite crucible and the crucible lid. Finally, conduct a sintering reaction to obtain the silicon carbide porous foam ceramic toughened by flour.
[0011] The beneficial effects of the present invention are as follows:
[0012] 1. Based on the existing polymer pre-impregnation method, the present invention uses low-gluten flour as the precursor of the reinforcing phase. Further, through the chemical reaction between the carbon derived from low-gluten flour and the silicon source, a highly tough silicon carbide porous foam ceramic is prepared. In a high-temperature argon environment, the carbon derived from low-gluten flour reacts with gaseous silicon to form silicon carbide, realizing the effective preparation of the highly tough silicon carbide porous foam ceramic.
[0013] 2. When the mass ratio of silicon carbide powder to low-gluten flour in the present invention is 20:1, the average pore diameter of the highly tough silicon carbide porous foam ceramic is 1050 μm, and it has a toughness of 10.56 MPa·m 1 / 2 .
[0014] 3. The present invention has the remarkable advantages of simple process and easy process control, and is suitable for large-scale industrial production. By using common raw materials such as silicon carbide powder, low-gluten flour, commercial polyurethane sponge, and waste silicon powder, the method takes dispersion, impregnation, carbonization, and reaction sintering as the core process steps, realizing the efficient preparation of the highly tough silicon carbide porous foam ceramic. Description of the Drawings
[0015] Figure 1 SEM pattern of the silicon carbide / carbon porous foam prepared in Step 5 of Example 1;
[0016] Figure 2 XRD pattern of the silicon carbide porous foam ceramic toughened by flour prepared in Example 1;
[0017] Figure 3 SEM pattern of the silicon carbide porous foam ceramic toughened by flour prepared in Example 1;
[0018] Figure 4 Pore size distribution pattern of the silicon carbide porous foam ceramic toughened by flour prepared in Example 1;
[0019] Figure 5 Toughness pattern of the silicon carbide porous foam ceramic toughened by flour prepared in Examples 1 to 5. Detailed Embodiments
[0020] Detailed Embodiment 1: A preparation method of a silicon carbide porous foam ceramic toughened by flour in this embodiment is carried out according to the following steps:
[0021] 1. Mix silicon carbide powder with cake flour to obtain a silicon carbide / cake flour mixed powder;
[0022] 2. Add deionized water to the silicon carbide / cake flour mixed powder and disperse evenly to obtain a silicon carbide / cake flour slurry;
[0023] 3. At room temperature, immerse a polyurethane sponge in the silicon carbide / cake flour slurry, then take it out and use a roll press to extrude the excess slurry to obtain a silicon carbide / cake flour / polyurethane block;
[0024] 4. Dry the silicon carbide / cake flour / polyurethane block to obtain a silicon carbide / cake flour / polyurethane preform;
[0025] 5. Carbonize the silicon carbide / cake flour / polyurethane preform under a nitrogen atmosphere to obtain a silicon carbide / carbon porous foam;
[0026] 6. Spread waste silicon powder at the bottom of a graphite crucible, place the silicon carbide / carbon porous foam above the waste silicon powder, then tightly cover the crucible lid, and use boron nitride slurry to seal the gap between the graphite crucible and the crucible lid. Finally, conduct a sintering reaction to obtain a silicon carbide porous foam ceramic toughened by flour.
[0027] The mechanism of the sintering reaction in Step 6 of this specific embodiment is as follows:
[0028] Si + C → SiC (reaction temperature 1500°C - 2000°C).
[0029] In Step 6 of this embodiment, the crucible is sealed in air and then placed in an argon furnace. The sealing is to reduce the loss of silicon vapor. However, due to the poor sealing effect, the air in the crucible will also become argon.
[0030] The beneficial effects of this embodiment are:
[0031] 1. Based on the existing polymer impregnation method, this embodiment uses cake flour as the precursor of the reinforcing phase. Further, through the chemical reaction between the carbon derived from cake flour and the silicon source, a high-toughness silicon carbide porous foam ceramic is prepared. In a high-temperature argon environment, the carbon derived from cake flour reacts with gaseous silicon to form silicon carbide, effectively preparing a high-toughness silicon carbide porous foam ceramic.
[0032] 2. When the mass ratio of silicon carbide powder to cake flour in this embodiment is 20:1, the average pore diameter of the high-toughness silicon carbide porous foam ceramic is 1050 μm, and it has a toughness of 10.56 MPa·m 1 / 2 .
[0033] 3. This embodiment has the remarkable advantages of simple process and easy process control, and is suitable for large-scale industrial production. By using common raw materials such as silicon carbide powder, low-gluten flour, commercial polyurethane sponge and waste silicon powder, this method takes dispersion, impregnation, carbonization and reaction sintering as the core process steps to realize the efficient preparation of high-toughness silicon carbide porous foam ceramics.
[0034] Specific Embodiment 2: The difference between this embodiment and Specific Embodiment 1 is that: the particle size of the silicon carbide powder described in Step 1 is 50nm - 70nm; the mass ratio of the silicon carbide powder to the low-gluten flour described in Step 1 is (10 - 30):1. Others are the same as Specific Embodiment 1.
[0035] Specific Embodiment 3: The difference between this embodiment and either Specific Embodiment 1 or 2 is that: the volume ratio of deionized water to the mass of the silicon carbide / low-gluten flour mixed powder described in Step 2 is (1 - 1.5) mL:1 g; the specific dispersion uniformity in Step 2 is carried out under the condition of a rotation speed of 1500 r / min - 2000 r / min for 5 min - 15 min. Others are the same as Specific Embodiment 1 or 2.
[0036] Specific Embodiment 4: The difference between this embodiment and any one of Specific Embodiments 1 to 3 is that: the pore size of the polyurethane sponge described in Step 3 is 15 PPI - 20 PPI. Others are the same as Specific Embodiment 3.
[0037] Specific Embodiment 5: The difference between this embodiment and any one of Specific Embodiments 1 to 4 is that: at room temperature in Step 3, the polyurethane sponge is impregnated in the silicon carbide / low-gluten flour slurry for 30 min - 60 min; the specific extrusion of the excess slurry using a roller press in Step 3 is carried out according to the following steps: the gap between the double rollers of the roller press is set to 10% - 20% of the height of the polyurethane sponge, and then carried out under the condition that the sponge traveling speed is 10 cm / min - 20 cm / min. Others are the same as Specific Embodiments 1 to 4.
[0038] Specific Embodiment 6: The difference between this embodiment and any one of Specific Embodiments 1 to 5 is that: the drying described in Step 4 is specifically carried out at a temperature of 85°C - 95°C for 12 h - 24 h. Others are the same as Specific Embodiments 1 to 5.
[0039] Specific Embodiment 7: The difference between this embodiment and any one of Specific Embodiments 1 to 6 is that: the carbonization described in Step 5 is specifically carried out in a nitrogen atmosphere at a rate of 0.5°C / min - 2°C / min, heated to 600°C - 800°C, and held at 600°C - 800°C in a nitrogen atmosphere for 2 h - 4 h, and finally cooled to room temperature naturally in a nitrogen atmosphere. Others are the same as Specific Embodiments 1 to 6.
[0040] Embodiment 8: The difference between this embodiment and any one of Embodiments 1 to 7 is that: the particle size of the waste silicon powder described in Step 6 is 400 mesh to 600 mesh; the mass ratio of the waste silicon powder to the silicon carbide / carbon porous foam described in Step 6 is (3 to 5):1. Others are the same as those in Embodiments 1 to 7.
[0041] Embodiment 9: The difference between this embodiment and any one of Embodiments 1 to 8 is that: the boron nitride slurry described in Step 6 is composed of 15% to 30% hexagonal boron nitride, 5% to 10% sodium silicate, 1% to 5% polyvinyl alcohol and the balance deionized water by mass percentage; in Step 6, a boron nitride ceramic member is used, and the silicon carbide / carbon porous foam is arranged 1 cm to 5 cm directly above the waste silicon powder. Others are the same as those in Embodiments 1 to 8.
[0042] Embodiment 10: The difference between this embodiment and any one of Embodiments 1 to 9 is that: the sintering reaction described in Step 6 is specifically carried out according to the following steps: in an argon atmosphere, first heat up to 800°C to 1000°C at a rate of 5°C / min to 10°C / min, and then heat up to 1500°C to 2000°C at a rate of 2.5°C / min to 5°C / min, and maintain for 4 h to 6 h under a nitrogen atmosphere and at a temperature of 1500°C to 2000°C, then in an argon atmosphere, cool down to 800°C to 1000°C at a rate of 2°C / min to 2.5°C / min, and finally cool down to room temperature at a cooling rate of 5°C / min to 10°C / min. Others are the same as those in Embodiments 1 to 9.
[0043] The following examples are used to verify the beneficial effects of the present invention:
[0044] Example 1:
[0045] A preparation method of silicon carbide porous foam ceramics for toughening flour is carried out according to the following steps:
[0046] I. Mix silicon carbide powder with low-gluten flour to obtain a silicon carbide / low-gluten flour mixed powder;
[0047] The average particle size of the silicon carbide powder is 60 nm; the mass ratio of the silicon carbide powder to the low-gluten flour is 20:1;
[0048] II. Add deionized water to the silicon carbide / low-gluten flour mixed powder and disperse for 15 min under the condition of a rotation speed of 1500 r / min to obtain a silicon carbide / low-gluten flour slurry;
[0049] The volume ratio of the deionized water to the mass of the silicon carbide / low-gluten flour mixed powder is 1 mL:1 g;
[0050] III. At room temperature, immerse the polyurethane sponge in the silicon carbide / low-gluten flour slurry for 30 min, then take it out. Use a rolling press, set the gap between the two rollers of the rolling press to 10% of the height of the polyurethane sponge, and then extrude the excess slurry under the condition that the sponge traveling speed is 10 cm / min to obtain a silicon carbide / low-gluten flour / polyurethane block;
[0051] The pore size of the polyurethane sponge described is 15 PPI;
[0052] IV. Under the condition that the temperature is 95 °C, dry the silicon carbide / low-gluten flour / polyurethane block for 24 h to obtain a silicon carbide / low-gluten flour / polyurethane preform;
[0053] V. Under a nitrogen atmosphere, heat the silicon carbide / low-gluten flour / polyurethane preform to 800 °C at a rate of 2 °C / min, and keep it at 800 °C for 4 h under a nitrogen atmosphere. Finally, cool it naturally to room temperature under a nitrogen atmosphere to obtain a silicon carbide / carbon porous foam;
[0054] VI. Spread the waste silicon powder at the bottom of the graphite crucible. Use a boron nitride ceramic component to place the silicon carbide / carbon porous foam 1 cm directly above the waste silicon powder, then cover the crucible lid tightly, and use boron nitride slurry to seal the gap between the graphite crucible and the crucible lid. Under an argon atmosphere, first heat it to 800 °C at a rate of 5 °C / min, then heat it to 2000 °C at a rate of 2.5 °C / min, and keep it at 2000 °C for 4 h under a nitrogen atmosphere. Then, under an argon atmosphere, cool it to 800 °C at a rate of 2 °C / min, and finally cool it to room temperature at a cooling rate of 5 °C / min to obtain a silicon carbide porous foam ceramic toughened with flour;
[0055] The average particle size of the waste silicon powder described is 500 mesh; the mass ratio of the waste silicon powder to the silicon carbide / carbon porous foam is 3:1;
[0056] The boron nitride slurry is composed of 30% hexagonal boron nitride, 10% sodium silicate, 5% polyvinyl alcohol and the balance deionized water by mass percentage.
[0057] The silicon carbide powder, low-gluten flour, boron nitride slurry and polyurethane sponge in this example are from Inner Mongolia Haitai Huacai Technology Co., Ltd.; the mass percentage of protein in the low-gluten flour is 6% - 9%; the purity of hexagonal boron nitride in the boron nitride slurry is 98%, the average particle size of hexagonal boron nitride is 10 μm, and the solid content of the boron nitride slurry is 45%. The waste silicon comes from Zhalainuoer Coal Industry Co., Ltd. with a purity of 99%.
[0058] The toughness of the silicon carbide porous foam ceramic toughened with flour prepared in Example 1 is 10.56 MPa·m1 / 2 。
[0059] Example 2: The difference between this example and Example 1 is that the mass ratio of the silicon carbide powder to the cake flour in Step 1 is 10:1. Others are the same as in Example 1.
[0060] The toughness of the cake flour toughened silicon carbide porous foam ceramic prepared in Example 2 is 2.32 MPa·m 1 / 2 。
[0061] Example 3: The difference between this example and Example 1 is that the mass ratio of the silicon carbide powder to the cake flour in Step 1 is 15:1. Others are the same as in Example 1.
[0062] The toughness of the cake flour toughened silicon carbide porous foam ceramic prepared in Example 3 is 5.79 MPa·m 1 / 2 。
[0063] Example 4: The difference between this example and Example 1 is that the mass ratio of the silicon carbide powder to the cake flour in Step 1 is 25:1. Others are the same as in Example 1.
[0064] The toughness of the cake flour toughened silicon carbide porous foam ceramic prepared in Example 4 is 9.28 MPa·m 1 / 2 。
[0065] Example 5: The difference between this example and Example 1 is that the mass ratio of the silicon carbide powder to the cake flour in Step 1 is 30:1. Others are the same as in Example 1.
[0066] The toughness of the cake flour toughened silicon carbide porous foam ceramic prepared in Example 5 is 8.21 MPa·m 1 / 2 。
[0067] Figure 1 is the SEM pattern of the silicon carbide / carbon porous foam prepared in Step 5 of Example 1; It can be seen from the figure that the silicon carbide / carbon porous foam has a certain honeycomb structure.
[0068] Figure 2 is the XRD pattern of the cake flour toughened silicon carbide porous foam ceramic prepared in Example 1; It can be seen from the figure that the main phase of the high-toughness silicon carbide porous foam ceramic is silicon carbide, indicating that the carbon in the porous foam carbon reacts with silicon vapor to form silicon carbide.
[0069] Figure 3 is the SEM pattern of the cake flour toughened silicon carbide porous foam ceramic prepared in Example 1; It can be seen from the figure that the high-toughness silicon carbide porous foam ceramic is mainly composed of silicon carbide blocks and silicon carbide nanowires, indicating that the high-toughness silicon carbide porous foam ceramic containing silicon carbide nanowires is successfully prepared by the method in the example.
[0070] Figure 4 Pore size distribution pattern of the flour toughened silicon carbide porous foam ceramic prepared in Example 1; It can be seen from the figure that the average pore size of the high toughness silicon carbide porous foam ceramic is 1050 μm.
[0071] Tested in accordance with the GB / T 1965-2023 standard; Figure 5 Toughness pattern of the flour toughened silicon carbide porous foam ceramics prepared in Examples 1 to 5; It can be seen from the figure that when the mass ratio of the silicon carbide powder to the low-gluten flour is 20:1, the toughness of the high toughness silicon carbide porous foam ceramic can reach up to 10.56 MPa·m 1 / 2 , indicating that the silicon carbide nanowires generated by the reaction can effectively enhance the toughness of the silicon carbide porous foam ceramic.
Claims
1. A method for preparing flour-toughened silicon carbide porous foam ceramics, characterized in that It is carried out in the following steps:
1. Mixing silicon carbide powder with low-gluten flour to obtain silicon carbide / low-gluten flour mixed powder; 2. Add deionized water to the silicon carbide / low-gluten flour mixed powder and disperse it evenly to obtain silicon carbide / low-gluten flour slurry; 3. At room temperature, immerse the polyurethane sponge in the silicon carbide / low-gluten flour slurry, then take it out and use a roller press to squeeze out the excess slurry to obtain a silicon carbide / low-gluten flour / polyurethane block; 4. Drying the silicon carbide / low-gluten flour / polyurethane block to obtain a silicon carbide / low-gluten flour / polyurethane preform; 5. Carbonizing the silicon carbide / low-gluten flour / polyurethane preform under a nitrogen atmosphere to obtain a silicon carbide / carbon porous foam; 6. Spread the waste silicon powder on the bottom of the graphite crucible, place the silicon carbide / carbon porous foam on top of the waste silicon powder, then cover the crucible tightly, and use boron nitride slurry to seal the gap between the graphite crucible and the crucible cover, and finally sinter the reaction to obtain flour-reinforced silicon carbide porous foam ceramics.
2. The method for preparing a flour-toughened silicon carbide porous foam ceramic according to claim 1, characterized in that The particle size of the silicon carbide powder described in step one is 50nm~70nm; the mass ratio of the silicon carbide powder described in step one to low-gluten flour is (10~30):
1.
3. The method for preparing a flour-toughened silicon carbide porous foam ceramic according to claim 1, characterized in that The mass ratio of the volume of deionized water to the silicon carbide / low-gluten flour mixed powder described in step 2 is (1-1.5) mL:1 g; the uniform dispersion described in step 2 is specifically dispersed for 5 min to 15 min at a rotation speed of 1500 r / min to 2000 r / min.
4. The method for preparing a flour-toughened silicon carbide porous foam ceramic according to claim 1, characterized in that The pore size of the polyurethane sponge described in step 3 is 15PPI-20PPI.
5. The method for preparing a flour-toughened silicon carbide porous foam ceramic according to claim 1, characterized in that In step three, at room temperature, the polyurethane sponge is immersed in the silicon carbide / low-gluten flour slurry for 30 minutes to 60 minutes; the use of a roller press to squeeze out excess slurry as described in step three is specifically carried out according to the following steps: the gap between the double rollers of the roller press is set to 10% to 20% of the height of the polyurethane sponge, and then the sponge is moved at a speed of 10 cm / min to 20 cm / min.
6. The method for preparing a flour-toughened silicon carbide porous foam ceramic according to claim 1, characterized in that The drying described in step 4 is specifically carried out at a temperature of 85° C. to 95° C. for 12 h to 24 h.
7. The method for preparing a flour-toughened silicon carbide porous foam ceramic according to claim 1, characterized in that The carbonization described in step 5 is specifically to heat up to 600°C to 800°C at a rate of 0.5°C / min to 2°C / min under a nitrogen atmosphere, and to keep the temperature at 600°C to 800°C for 2h to 4h under a nitrogen atmosphere, and finally to cool naturally to room temperature under a nitrogen atmosphere.
8. The method for preparing a flour-toughened silicon carbide porous foam ceramic according to claim 1, characterized in that The particle size of the waste silicon powder described in step six is 400 mesh to 600 mesh; the mass ratio of the waste silicon powder described in step six to the silicon carbide / carbon porous foam is (3 to 5):
1.
9. The method for preparing a flour-toughened silicon carbide porous foam ceramic according to claim 1, characterized in that The boron nitride slurry described in step six is composed of 15% to 30% hexagonal boron nitride, 5% to 10% sodium silicate, 1% to 5% polyvinyl alcohol and the balance deionized water in mass percentage; in step six, a boron nitride ceramic component is used, and the silicon carbide / carbon porous foam is set 1cm to 5cm above the waste silicon powder.
10. The method for preparing a flour-toughened silicon carbide porous foam ceramic according to claim 1, characterized in that The sintering reaction described in step six is specifically carried out according to the following steps: in an argon atmosphere, first heat up to 800°C~1000°C at a rate of 5°C / min~10°C / min, then heat up to 1500°C~2000°C at a rate of 2.5°C / min~5°C / min, and maintain for 4h~6h in a nitrogen atmosphere and a temperature of 1500°C~2000°C, then cool down to 800°C~1000°C at a rate of 2°C / min~2.5°C / min in an argon atmosphere, and finally cool down to room temperature at a cooling rate of 5°C / min~10°C / min.