Preparation method of C/SiC composite material with vibrissa-nostril-like structure
Technical Field
The invention belongs to the field of porous materials, and particularly relates to a preparation method of a C/SiC composite material with a vibrissa-nostril-like structure.
Background
Foam carbon (foam carbon) refers to a foamed porous carbon material. Carbon foam is a lightweight porous material with a three-dimensional network structure composed of cells and interconnected cell walls. Besides the conventional properties of carbon materials, the carbon foam has the characteristics of small density, high strength, thermal shock resistance, easiness in processing and the like, and good physical and chemical properties of wave absorption and the like, and the excellent properties enable the carbon foam to be applied to various technical fields of chemical industry, aerospace, electronics and the like.
The foam carbon has the high-temperature stability of the C material and the heat insulation performance of the light material. It is a potential high-temperature thermal insulation material for aviation. However, most of the carbon foams are made of organic substances through high-temperature foaming and carbonization, and the materials obtained by the method have large pores (mostly micron-sized or more), and the pores can provide channels for convection and radiation heat transfer at high temperature, so that the thermal conductivity of the materials is obviously increased along with the temperature rise, and the high-temperature heat insulation performance of the materials is not good and does not reach the expected level of people.
Disclosure of Invention
In order to solve the problem of poor high-temperature heat insulation performance of carbon foam, the invention aims to provide a preparation method of a C/SiC composite material with a vibrissa-like nostril structure.
The invention adopts the following technical scheme for achieving the purpose:
a C/SiC composite material with the structure similar to nasal hair and nostril is prepared from starch and SiO2Is prepared from water as solvent, disperser and waterThe foaming agent is prepared by forming silicon dioxide-containing foam carbon by carrying out sol, foaming, gel curing and carbonization on starch; after in-situ high-temperature carbon thermal reduction reaction, a large number of SiC nanowires grow in air holes of foam carbon, the generation of the SiC nanowires modifies the pore structure of the foam C, limits convection and radiation heat transfer, and obviously reduces the thermal conductivity of the material, and the specific steps are as follows:
1) preparing a silicon-containing starch sol:
putting starch, silicon dioxide, water and a dispersing agent into a planetary ball mill according to a certain proportion, and ball-milling and uniformly mixing to obtain stable silicon dioxide-containing starch sol;
2) a foaming step:
adding a foaming agent into the silica-containing starch sol obtained in the step 1), stirring for 20min by using a stirrer, and standing for 2 h at the temperature of 30-45 ℃ to obtain porous sol;
3) and (3) gel curing:
heating the porous sol obtained in the step 2) in a water bath at 80-100 ℃, preserving heat for 40 min, and drying at 110 ℃ to constant weight to obtain porous gel;
4) and (3) carbonizing:
carbonizing the porous gel obtained in the step 3) to constant weight at 600 ℃ under the protection of nitrogen or argon to obtain silicon dioxide-containing foamy carbon;
5) a carbothermic reduction reaction step:
and (3) heating the foam carbon containing the silicon dioxide obtained in the step (4) to 1550-1850 ℃ at a heating rate of 10-15 ℃/min under the protection of argon, preserving heat at 1500-1800 ℃ for 3-10 h, and cooling along with a furnace to obtain the C/SiC composite material with the vibrissa-nostril structure.
The starch in the step 1) is one or more of wheat starch, corn starch, sweet potato starch, sorghum starch and the like.
The dispersant in the step 1) is one or more of polyacrylamide, CAMTMENT FS20 and tetramethylethylenediamine.
The foaming agent in the step 2) is one or more of lauryl triethanolamine sulfate, yeast, egg white, baking soda and the like.
The mass ratio of the starch to the silicon dioxide to the foaming agent to the water to the dispersing agent is 100: 5-15: 0.5-10: 80-130: 0.02-1.
The preparation method of the C/SiC composite material with the vibrissa-nostril-like structure, which is disclosed by the invention, has the following characteristics by adopting the technical scheme:
1. the material prepared by the method can resist the high temperature of 2000 ℃; the melting point or decomposition temperature of C and SiC in the composite material is more than 2300 ℃, and the obtained composite material can be used at higher temperature
2. The material has excellent high-temperature heat-insulating property. According to the method, the SiC nanowires with high purity and small diameter (< 150 nm) and large length (>100 microns) are obtained through carbon thermal in-situ reaction, the nanowires modify the pore structure performance of the foam carbon, the composite material has a nanometer pore structure, convection and radiation heat transfer of the foam carbon are effectively reduced, and the material has low high-temperature heat conductivity.
3. The method uses starch and SiO2The raw materials are green and cheap, and the preparation process is simple.
Drawings
FIG. 1 is a scanning electron micrograph of the C/SiC composite material prepared in example 1 of the process of the present invention.
FIG. 2 is a scanning electron micrograph of SiC nanowires in the foam gas of the composite material prepared in example 1 of the method of the present invention.
Detailed description of the preferred embodiments
The invention is described with reference to the accompanying drawings and specific examples:
example 1: putting 100 parts of wheat starch, 9 parts of silicon dioxide, 105 parts of water and 0.5 part of polyacrylamide into a planetary ball mill, and ball-milling for 2 hours at the speed of 30 r/min to obtain the product containing SiO2The starch sol of (a); adding 1 part of yeast into the sol, stirring for 20min at the speed of 800 r/min, and preserving heat for 2 h at 35 ℃ to obtain porous sol; putting the porous sol into a water bath, keeping the temperature at 100 ℃ for 40 min, taking out a sample, putting the sample into an oven, and drying the sample at 110 ℃ to constant weight to obtain porous gel; keeping the temperature of 600 ℃ in a nitrogen atmosphere until the weight is constant to obtain porous carbon; under the condition of argon protection, the method comprises the following steps of,raising the temperature to 1530 ℃ at the heating rate of 15 ℃/min, keeping the temperature for 10 h, and cooling along with the furnace, wherein the properties of the prepared C/SiC composite material with the vibrissa-nostril-like structure are shown in the table 1, the microstructure photo of the composite material is shown in the table 1, and the microstructure photo of the SiC nanowires in the foam carbon pores is shown in the table 2.
Example 2: putting 100 parts of sorghum starch, 10 parts of silicon dioxide, 90 parts of water and 0.1 part of tetramethylethylenediamine into a planetary ball mill for ball milling for 2 hours at a speed of 30 r/min to obtain the product containing SiO2The starch sol of (a); adding 1 part of yeast into the sol, stirring for 20min at the speed of 800 r/min, and preserving heat for 2 h at 35 ℃ to obtain porous sol; putting the porous sol into a water bath, keeping the temperature at 95 ℃ for 40 min, taking out a sample, putting the sample into an oven, and drying the sample at 110 ℃ to constant weight to obtain porous gel; keeping the temperature at 600 ℃ in a nitrogen atmosphere until the weight is constant to obtain porous carbon; and under the protection of argon, heating to 1600 ℃ at a heating rate of 14 ℃/min, preserving the heat for 4 h, and cooling along with the furnace to obtain the C/SiC composite material with the vibrissa-nostril structure.
Example 3: putting 100 parts of corn starch, 11 parts of silicon dioxide, 85 parts of water and 0.05 part of CAMTMENT FS20 into a planetary ball mill, and ball-milling for 2 hours at 30 r/min to obtain the product containing SiO2The starch sol of (a); adding 1 part of yeast and 3 parts of baking soda into the sol, stirring at 800 r/min for 20min, and keeping the temperature at 35 ℃ for 2 h to obtain porous sol; putting the porous sol into a water bath, preserving the heat at 98 ℃ for 40 min, taking out a sample, putting the sample into an oven, and drying the sample at 110 ℃ to constant weight to obtain porous gel; keeping the temperature at 600 ℃ in a nitrogen atmosphere to obtain porous carbon with constant weight; under the protection of argon, the temperature is raised to 1800 ℃ at the heating rate of 12 ℃/min, and the temperature is kept for 2 h and then the C/SiC composite material with the vibrissa-like-nostril structure is obtained after furnace cooling.
Example 4: putting 100 parts of wheat starch, 10 parts of silicon dioxide, 110 parts of water and 0.5 part of polyacrylamide into a planetary ball mill, and ball-milling for 2 hours at the speed of 30 r/min to obtain the product containing SiO2The starch sol of (a); adding 5 parts of dodecyl sulfuric acid triethanolamine into the sol, stirring for 20min at the speed of 800 r/min, and keeping the temperature at 35 ℃ for 2 h to obtain porous sol; putting the porous sol into a water bath, preserving the heat at 100 ℃ for 40 min, taking out a sample, putting the sample into an oven, and drying the sample at 110 ℃ to constant weight to obtain porous gel; nitrogen gasKeeping the temperature at 600 ℃ and balancing the weight to obtain porous carbon; under the protection of argon, the temperature is raised to 1550 ℃ at the heating rate of 10 ℃/min, and the C/SiC composite material with the vibrissa-nostril structure is obtained after the temperature is preserved for 10 h at 1550 ℃. .
Example 5: putting 100 parts of sorghum starch, 8 parts of silicon dioxide, 90 parts of water and 0.05 part of CAMTMENT FS20 into a planetary ball mill for ball milling for 2 hours at a speed of 30 r/min to obtain the product containing SiO2The starch sol of (a); adding 5 parts of lauryl triethanolamine sulfate into the sol, stirring for 10min at a speed of 800 r/min, and keeping the temperature at 25 ℃ for 2 h to obtain porous sol; putting the porous sol into a water bath kettle, preserving the heat at 94 ℃ for 40 min, and drying at 110 ℃ to constant weight to obtain porous gel; keeping the temperature of 600 ℃ in a nitrogen atmosphere until the weight is constant to obtain porous carbon; and under the protection of argon, heating to 1750 ℃ at the heating rate of 10-15 ℃/min, preserving heat for 4 hours, and cooling along with the furnace to obtain the C/SiC composite material with the vibrissa-nostril like structure.
TABLE 1