Patent Application
20240383815
The present application belongs to the field of high-temperature thermal insulation materials, particularly relates to a high-temperature-resistant and oxidation-resistant light-weight heat-insulation foam material and a preparation method thereof, and more specifically to a SiBCN foam material, a SiHfBCN foam material, a SiBCN/C composite foam material, or a SiHfBCN/C composite foam material and preparation method thereof.
Foam materials with high porosity, low density, and low thermal conductivity are common thermal insulation materials, such as polyurethane foam, alumina foam, silicon carbide foam, carbon foam, etc. Among the above-mentioned foams, the lightweight carbon foam with three-dimensional mesh structure has broad application prospects in the field of heat (thermal) insulation because of its low density, low thermal conductivity, low thermal expansion coefficient, and good high temperature stability. However, although carbon foam can be used at temperatures up to 2000° C. in an inert environment, it is easily oxidized in an aerobic environment, and it can be used in air for a long time at only 350° C. and has low mechanical strength, which leads to its application being limited. Therefore, the development of a light-weight heat-insulation foam material with high temperature resistance and oxidation resistance functions has important application value.
In view of the shortcomings and defects existing in the prior art, the present application aims to provide a high-temperature-resistant and oxidation-resistant light-weight heat-insulation foam material and a preparation method thereof. The SiBCN foam material, SiHfBCN foam material, SiBCN/C composite foam material or SiHfBCN/C composite foam material obtained by the present application has the advantages of high temperature resistance, a low thermal conductivity, oxidation resistance, a low density, and a high strength.
In order to achieve the above-mentioned purpose, the first aspect of the present application provides a high-temperature-resistant and oxidation-resistant light-weight heat-insulation foam material, using the following technical solutions: A high-temperature-resistant and oxidation-resistant light-weight heat-insulation foam material, being one selected from the group consisting of a SiBCN foam material, a SiHfBCN foam material, a SiBCN/C composite foam material and a SiHfBCN/C composite foam material, and prepared from a precursor solution through processes of template impregnation, curing, drying and cracking;
The SiBCN/C composite foam material is a composite foam material formed by attaching SiBCN materials to the surface of C layer; The SiHfBCN/C composite foam material is a composite foam material formed by attaching SiHfBCN materials to the surface of C layer.
In the present application, the SiBCN foam material or the SiHfBCN foam material is obtained by performing processes of impregnation, curing, drying, and cracking sequentially using the polyurethane foam as the template and the SiBCN precursor solution or the SiHfBCN precursor solution as the impregnation solution, wherein the polyurethane foam is chosen as the template for the main purpose that the polyurethane foam has a unique pore structure, its raw materials are easy available at low cost, and in the cracking process, the polyurethane foam will be ablated without residue, so as to obtain the SiBCN foam material or the SiHfBCN foam material with porous structure. The main purpose of choosing the SiBCN precursor solution as the impregnation solution is that during the curing process and cracking process (i.e., ceramic transformation process) of the SiBCN precursor, free carbon will combined with BN to form BNCx structure, which can greatly reduce the reaction activity of the free carbon and the diffusion rate of atoms in the system, thus preventing the carbon thermal reduction reaction between the free carbon and Si3N4 in SiBCN foam material, at the same time, the special SiOxN4-x structure in the foam material will also prevent the diffusion of oxygen atoms, making SiBCN foam material with good high-temperature resistance and oxidation resistance. The main purpose of selecting the SiHfBCN precursor solution as the impregnating solution is that the high temperature element Hf in the SiHfBCN precursor can further improve the high-temperature resistance of the foam material, and the SixOyHfz structure formed after oxidation can prevent the diffusion of oxygen atoms, thus making the SiHfBCN ceramic foam also have good antioxidant properties.
In the present application, the SiBCN foam material or the SiHfBCN foam material is obtained by performing processes of impregnation, curing, drying and cracking sequentially using the organic carbon-modified polyurethane foam as the template and the SiBCN precursor solution or the SiHfBCN precursor solution as the impregnation solution, wherein the main purpose of selecting the organic carbon-modified polyurethane foam as the template is to modify polyurethane foam by using organic carbon source, so as to obtain polyurethane foam material with carbon skeleton. Then, in the subsequent cracking process, the polyurethane foam material will be ablated without residue, thus enabling the carbon skeleton to be compounded with the SiBCN foam material to obtain a SiBCN/C multilayer skeleton foam material, or with the SiHfBCN foam material to obtain a SiHfBCN/C multilayer skeleton foam material. Carbon has a higher temperature resistance grade, and the foam material with the C-layer has a higher temperature resistance performance, and a higher strength retention under high temperature condition.
In the above-mentioned high-temperature-resistant and oxidation-resistant light-weight heat-insulation foam material, as one preferred embodiment, the SiBCN foam material has a density of equal to and greater than 0.07 g/cm3, a room temperature compressive strength of equal to and greater than 0.3 MPa, and a room temperature thermal conductivity of equal to and greater than 0.046 W/(m·K);
The second aspect of the present application provides a preparation method of the high-temperature-resistant and oxidation-resistant light-weight heat-insulation foam material, comprising the following steps:
The impregnation process in the present application means that the template is completely impregnated into the impregnating solution for adsorption, and the impregnation process completed when the template is saturated with adsorption. The different structure of the template has an effect on the microstructure, density, strength, and thermal conductivity of the resulting foam material.
In the above-mentioned preparation method, as one preferred embodiment, a mass fraction of the SiBCN precursor in the SiBCN precursor solution or a mass fraction of the SiHfBCN precursor in the SiHfBCN precursor solution is 5%˜80% (such as 7%, 25%, 38%, 46%, 57%, 68%, and 75%), and a mass of the catalyst is 0.5%˜5% (such as 0.8%, 1.5%, 2.5%, 3.5%, and 4.5%) of a mass of the SiBCN precursor or the SiHfBCN precursor;
In the present application, the mass fraction of the SiBCN precursor solution or the SiHfBCN precursor solution affects the microstructure, density, strength, and thermal conductivity of the resulting foam material. The larger the mass fraction of the SiBCN precursor solution or the SiHfBCN precursor solution, the higher density, higher strength and higher thermal conductivity of the resulting foam material. The aim of adding the catalyst to the SiBCN precursor solution or the SiHfBCN precursor solution is to catalyze the curing reaction in the curing process. If the concentration of the added catalyst is too high, the reaction rate will be too high, which is not conducive to the formation of a uniform porous structure of the foam material; if the concentration of the added catalyst is too low, the reaction rate will be too slow.
In the above-mentioned preparation method, as one preferred embodiment, the organic solvent is liquid alkane;
In the present application, the main purpose of choosing the above-mentioned organic solvent(s) is (are) that such solvents can dissolve the SiBCN precursors or the SiHfBCN precursors, at the same time, such solvent does not dissolve polyurethane foam materials and can be compatible with polyurethane foam materials; moreover, the above-mentioned organic solvents are non-toxic or low toxicity, and will not cause harm to human health when used.
In the above-mentioned preparation method, as one preferred embodiment, the catalyst is at least one of the group consisting of diisopropylbenzene peroxide (dicumyl peroxide), dibenzoyl peroxide, azodiisobutyronitrile, azodiisoheptanitrile and divinylbenzene;
In the above-mentioned preparation method, as one preferred embodiment, the organic carbon-modified polyurethane foam is prepared by immersing the polyurethane foam in an organic carbon source and then curing the organic carbon source attached to the polyurethane foam;
In the above-mentioned preparation method, as one preferred embodiment, when the organic carbon source is furfuryl alcohol, the process for preparing the organic carbon-modified polyurethane foam further includes adding formic acid or methyl p-toluenesulfonate as a catalyst into the furfuryl alcohol;
When the organic carbon source is a phenolic resin, the process for preparing the organic carbon-modified polyurethane foam further includes adding hexamethylenetetramine as a catalyst and anhydrous ethanol as a solvent into the phenolic resin;
When the organic carbon source is resorcinol-formaldehyde sol, the process for preparing the organic carbon-modified polyurethane foam further includes adding at least one selected from the group consisting of sodium carbonate, sodium hydroxide, and barium hydroxide as a catalyst and deionized water as a solvent into the resorcinol-formaldehyde sol;
In the present application, when the polyurethane foam is immersed in the organic carbon source, the purpose of adding a catalyst simultaneously is to catalyze the curing reaction of the organic carbon source.
In the above-mentioned preparation method, as one preferred embodiment, in the process for preparing the organic carbon-modified polyurethane foam, the used polyurethane foam has a reticulated open-cell structure with an average pore diameter of 1 μm˜1 mm (such as 20 μm, 100 μm, 300 μm, 500 μm and 800 μm); preferably, the polyurethane foam has a density of 0.025˜0.1 g/cm3 (such as 0.030 g/cm3, 0.040 g/cm3, 0.050 g/cm3, 0.070 g/cm3and 0.090 g/cm3) and a porosity of more than 92%.
In the present application, when the average pore size of polyurethane foam is too small, it is not conducive to the preparation of blocks and the resulting foam material is easy to crack; when the average pore size of polyurethane foam is too large, the thermal conductivity of the resulting foam material is too large and the strength is low.
In the above-mentioned preparation method, as one preferred embodiment, in the process for preparing the organic carbon-modified polyurethane foam, a vacuum degree of the immersing is 10 Pa˜105 Pa (such as 100 Pa, 500 Pa, 103 Pa and 104 Pa), and an immersing time is 0.1˜2 h (such as 0.5 h, 0.8 h, 1.2 h and 1.5 h).
In the above-mentioned preparation method, as one preferred embodiment, the polyurethane foam used directly as the template has a reticulated open-cell structure with an average pore size of 1 μm˜1 mm (such as 20 μm, 100 μm, 300 μm, 500 μm and 800 μm); preferably, the polyurethane foam has a density of 0.025˜0.1 g/cm3 (such as 0.030 g/cm3, 0.040 g/cm3, 0.050 g/cm3, 0.070 g/cm3 and 0.090 g/cm3) and a porosity of more than 92%.
In the above-mentioned preparation method, as one preferred embodiment, in the impregnation process, a vacuum degree is 10 Pa˜105 Pa (such as 100 Pa, 500 Pa, 103 Pa and 104 Pa) and an impregnation time is 1˜2 h (such as 0.5 h, 0.8 h, 1.2 h and 1.5 h).
In the above-mentioned preparation method, as one preferred embodiment, the curing process is to raise a temperature from room temperature to 100˜280° C. (such as 120° C., 150° C., 220° C. and 240° C.) at a heating rate of 0.01˜5° C./min (such as 0.05° C./min, 0.5° C./min, 1° C./min, 2° C./min and 4° C./min) under a non-oxygen sealing condition (non-oxygen, gas circulation), and to keep the temperature for 2˜8 hours.
In the curing process of the present application, if the heating rate is too large, the resulting foam material will be prone to cracking; and if the heating rate is too small, the curing process cycle will be too long and the energy consumption will be high.
In the above-mentioned preparation method, as one preferred embodiment, the drying process is to raise a temperature from room temperature to 100˜280° C. (such as 120° C., 150° C., 220° C. and 240° C.) at a heating rate of 0.01˜1° C./min (such as 0.03° C./min, 0.08° C./min, 0.1° C./min, 0.5° C./min and 0.8° C./min) in an inert atmosphere of nitrogen or argon (non-oxygen and gas circulation), and then keep the temperature for 4˜24 hours (such as 5 h, 10 h, 15 h, 18 h and 22 h).
In the present application, the main purpose of performing the drying process is to remove the organic solvent from the system. In the drying process, if the heating rate is too large, the resulting foam material will be prone to cracking, and if the heating rate is too small, the drying process cycle will be too long and the energy consumption will be high.
In the above-mentioned preparation method, as one preferred embodiment, the cracking process is to raise a temperature from room temperature to 800˜1500° C. (such as 1000° C., 1100° C., 1200° C., 1300° C. and 1400° C.) at a heating rate of 0.1˜5° C./min (such as 0.3° C./min, 0.5° C./min, 1° C./min, 2° C./min and 4° C./min) in an inert atmosphere of nitrogen or argon (non-oxygen and gas circulation), and then keep the temperature for 2˜8 hours (such as 3 h, 4 h, 5 h, 6 h and 7h).
In the cracking process of the present application, if the heating rate is too large, the resulting foam material will be prone to cracking; and if the heating rate is too small, the cracking process cycle will be too long and the energy consumption will be high. In the cracking process, if the cracking temperature is too high, the thermal conductivity of the obtained foam material will be too high; and if the cracking temperature is too low, the cracking will be insufficient. Compared with the prior art, the present application has the following beneficial effects:
The SiBCN foam material and the SiHfBCN foam material prepared by the present application have the advantages of a light weight, a high strength, oxidation resistance and a low thermal conductivity. SiBCN and SiHfBCN have good compatibility with carbon, and the resulting SiBCN/C composite foam material or SiHfBCN/C composite foam material has the advantages of a light weight, a high strength, high temperature resistance, a low thermal conductivity and oxidation resistance.
The high-temperature-resistant, oxidation-resistant, light-weight heat-insulation foam material and its preparation method of the present application will be described below with reference to the accompanying drawings and examples. It should be understood that these examples are only used to illustrate the present application and not to limit the scope of the present application. It should be understood that, after reading the content of the present application, those skilled in the art application make various changes and modifications to the present application, and these equivalent forms also fall within the scope defined by the appended claims of the present application.
The SiBCN precursor used in the following examples is polyborosilazane (the number-average molecular weight of polyborosilazane is 400˜600 g/mol, and the viscosity at 80° C. is 100˜300 cp), purchased from the Institute of Chemistry, Chinese Academy of Sciences, or Shandong Zibo Industry and Trade Co., Ltd. The SiHfBCN precursor (the number-average molecular weight of hafnium-containing polyborosilazane is 500˜1000 g/mol, and the room temperature viscosity is 100˜500 cp) was made in the laboratory (the specific preparation method is described below), wherein the polysilazane HTT1800 is a polysilazane containing vinyl active groups (its molecular structure is described below), purchased from Guangzhou Honghai Chemical Technology Co., Ltd., and the rest of the raw materials can be purchased from the market.
Preparation of SiHfBCN precursor: at room temperature, toluene was pre-added in a Schlenk reactor filled with inert gas atmosphere, and polysilazane HTT1800 was dissolved in toluene to prepare a solution with volume fraction of 40%; then, the toluene solution of Hf (NEt2)4 with volume fraction of 6% was added dropwise to the Schlenk reactor (wherein the volume ratio of Hf (NEt2)4 to polysilazane HTT1800 is 1:9), and stirred for 2 h after mixing; the reaction system was cooled to −50° C., and the toluene solution of borane dimethyl sulfide BH3·(CH3)2S with volume fraction of 6% was added dropwise to the mixture solution (wherein the volume ratio of BH3·(CH3)2S to polysilazane HTT1800 is 1:18), and stirred for 2 hours; then the reaction system was heated to room temperature for 24 hours; finally, the SiHfBCN precursor can be obtained by evaporating the toluene at 50-60° C. under vacuum.
The specific embodiment of the present application provides a high-temperature-resistant and oxidation-resistant light-weight heat-insulation foam material, wherein the preparation method of a SiBCN foam material or a SiHfBCN foam material, as shown in
Another specific embodiment of the present application provides a high-temperature-resistant and oxidation-resistant light-weight heat-insulation foam material,
A SiBCN foam material, whose preparation method comprises the following steps:
The SiBCN foam material performance test are as follows: The density test is carried out in accordance with GB/T 17911-2006 (Refractory products-method of test for ceramic fibre products); the room temperature compressive strength test is carried out according to GB/T 1453-2005 (Test method for flatwise compression properties of sandwich constructions or cores); the thermal conductivity test is carried out in accordance with GB/T 10295-2008 (Thermal insulation—Determination of steady-state thermal resistance and related properties—Heat flow meter apparatus).
The microscopic morphology of the prepared SiBCN foam material sample is shown in
A SiHfBCN foam material, whose preparation method comprises the following steps:
The microscopic morphology of the prepared SiHfBCN foam material sample is not much different from that in
A SiBCN/C composite foam material, whose preparation method comprises the following steps:
The microscopic morphology of the prepared SiBCN/Ccomposite foam material sample is not much different from that in
A SiHfBCN/C composite foam material, whose preparation method comprises the following steps:
S6.Cracking process: Increase a temperature of the SiHfBCN/C pre-solid foam from room temperature to 1500° C. at a heating rate of 3° C./min under an inert environment of argon, and then keep the temperature for 2 hours to obtain the SiHfBCN/C composite foam material.
The microscopic morphology of the prepared SiHfBCN/C composite foam material sample is not much different from that in
Example 5 is the same as Example 1, except that the preparation of the precursor solution in S1 is different.
S1.Preparation of the precursor solution in Example 5: Dissolve a SiBCN precursor in n-nonane to prepare a 20 wt % SiBCN precursor solution, add 2.5% dicumyl peroxide as catalyst by mass of the SiBCN precursor, and stir for 20 minutes under the condition of sealing until the mixture is uniform.
The microscopic morphology of the prepared SiBCN foam material sample is shown in
Example 6 is the same as Example 1, except that the preparation of the precursor solution in S1 is different.
S1.The preparation of the precursor solution in Example 6: Dissolve a SiBCN precursor in n-nonaneto prepare a 30 wt % SiBCN precursor solution, add 5% dicumyl peroxide as catalyst by mass of the SiBCN precursor, and stir for 30 minutes under the condition of sealing until the mixture is uniform.
The microscopic morphology of the prepared SiBCN foam material sample is shown in
Example 7 is the same as Example 2, except that the preparation of the precursor solution in S1 is different.
S1. The preparation of the precursor solution in Example 7: Dissolve a SiHfBCN precursor in n-tridecane to prepare a 20 wt % SiHfBCN precursor solution, then add 2.5% dicumyl peroxide as catalyst by mass of the SiHfBCN precursor, and stir for 20 minutes under the condition of sealing until the mixture is uniform.
The microscopic morphology of the prepared SiHfBCN foam material sample is not much different from that in
Example 8 is the same as Example 2, except that the preparation of the precursor solution in S1 is different.
S1. The preparation of the precursor solution in Example 8: Dissolve a SiHfBCN precursor in n-tridecane to prepare a 30 wt % SiHfBCN precursor solution, then add 5% dicumyl peroxide as catalyst by mass of the SiHfBCN precursor, and stir for 30 minutes under the condition of sealing until the mixture is uniform.
The microscopic morphology of the prepared SiHfBCN foam material sample is not much different from that in
Example 9 is the same as Example 3, except that the preparation of the precursor solution in S2 is different.
The microscopic morphology of the prepared SiBCN/C composite foam material sample is not much different from that in
Example 10 is the same as Example 3, except that the preparation of the precursor solution in S2 is different.
The microscopic morphology of the prepared SiBCN/C composite foam material sample is not much different from that in
Example 11 is the same as Example 4, except that the preparation of the precursor solution in S2 is different.
The microscopic morphology of the prepared SiHfBCN composite foam material sample is not much different from that in
Example 12 is the same as Example 4, except that the preparation of the precursor solution in S2 is different.
The microscopic morphology of the prepared SiHfBCN composite foam material sample is not much different from that in
The above descriptions are only the preferred embodiments of the present application and are not intended to limit the present application. Any modification, equivalent replacement, improvement and the like made within the spirit and principles of the present application shall fall within the scope of protection of the pending claims of the present application.
| Number | Date | Country | Kind |
|---|---|---|---|
| 202111289414.7 | Nov 2021 | CN | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/CN2021/128855 | 11/5/2021 | WO |
