CN113024819A

CN113024819A - SiBCN ceramic precursor and synthesis method thereof

Info

Publication number: CN113024819A
Application number: CN202110242944.XA
Authority: CN
Inventors: 邵长伟; 龙鑫; 王兵; 王应德; 王小宙; 苟燕子; 韩成
Original assignee: National University of Defense Technology
Current assignee: National University of Defense Technology
Priority date: 2021-03-05
Filing date: 2021-03-05
Publication date: 2021-06-25
Anticipated expiration: 2041-03-05
Also published as: CN113024819B

Abstract

The invention discloses a SiBCN ceramic precursor and a synthesis method thereof. The synthesis method of the SiBCN ceramic precursor uses decaborane and an organosilicon compound as raw materials, and utilizes the dehydrogenation condensation reaction of the decaborane and the organosilicon compound, which is simple and efficient. A new SiBCN ceramic precursor is synthesized. The reaction can be carried out at room temperature. The synthesis yield reaches more than 82 wt%. There are no other by-products except hydrogen. The atom utilization rate is high, which is convenient for large-scale production. The synthesized Si-C ‑N‑B multi-component ceramic precursors have good solubility and high ceramic yield, and are suitable for a variety of solution processing processes to prepare complex-shaped ceramic materials.

Description

SiBCN ceramic precursor and synthesis method thereof

Technical Field

The invention relates to the technical field of new materials, in particular to a SiBCN ceramic precursor and a synthesis method thereof.

Background

The polyborosilazane is an important precursor for preparing the multi-element composite ceramic material, can be used for preparing various forms of ceramic materials such as SiBCN ceramic fiber, SiBN ceramic fiber, SiBCN ceramic matrix composite material and the like by combining different processing and forming methods with high-temperature inorganic formation, and can also be used for enhancing the oxidation resistance of other carbon materials. Researchers at home and abroad construct various SiBCN ceramic precursors, some are obtained by adding boron element into Si-N main chain polymer for modification, and some are obtained by performing co-ammonolysis polymerization directly through chlorosilane and chloroborane. Due to the covalent bond formation method of elements such as boron, nitrogen, silicon and the like, the synthetic products are often multi-branched polymers, and the synthetic process requires low temperature conditions and generates a considerable amount of byproducts.

Disclosure of Invention

The invention provides a SiBCN ceramic precursor and a synthesis method thereof, which are used for overcoming the defects that the synthesized product is a multi-branched polymer, the synthesis process needs low temperature condition and generates a considerable amount of byproducts and the like in the prior art.

In order to achieve the above purpose, the invention provides a method for synthesizing a SiBCN ceramic precursor, which comprises the following steps:

s1: weighing decaborane and an organic silicon compound according to the mass ratio of 1: 1;

s2: dissolving the decaborane in anhydrous tetrahydrofuran to obtain a decaborane solution;

dissolving the organic silicon compound in anhydrous tetrahydrofuran to obtain an organic silicon compound solution;

s3: selecting a reaction kettle with a stirrer, replacing air in the reaction kettle with inert gas, and adding the decaborane solution into the reaction kettle;

s4: adding an organic silicon compound solution into a reaction kettle under the condition of stirring;

s5: after the charging is finished, continuously stirring at room temperature for 10-20 h, and then carrying out reduced pressure distillation for 10-20 h under the condition of constant-temperature water bath at 60 ℃ to obtain the SiBCN ceramic precursor

In order to achieve the purpose, the invention also provides a SiBCN ceramic precursor synthesized by the synthesis method.

Compared with the prior art, the invention has the beneficial effects that:

the synthesis method of the SiBCN ceramic precursor provided by the invention uses decaborane (B)₁₀H₁₄) And an organic silicon compound is used as a raw material, a new SiBCN ceramic precursor is simply and efficiently synthesized by utilizing the dehydrogenation condensation reaction of decaborane and the organic silicon compound, the reaction can be carried out at room temperature, the synthesis yield reaches over 90 wt%, no other by-products except hydrogen exist, the atom utilization rate is high, the large-scale production is facilitated, and the synthesized Si-C-N-B multi-element ceramic precursor has good solubility and high ceramic yield, and is suitable for various solution processing technologies to prepare ceramic materials with complex shapes.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the structures shown in the drawings without creative efforts.

FIG. 1 is an infrared spectrum of a SiBCN ceramic precursor of example 1 in accordance with the present invention;

FIG. 2 is an XPS elemental analysis spectrum of a SiBCN ceramic precursor in example 1 of the present invention;

FIG. 3 is a graph of the thermal weight loss of the SiBCN ceramic precursor of example 1 of the present invention;

FIG. 4 is a comparison graph of the IR spectra of SiBCN ceramic precursors of examples 1, 2, and 3 of the present invention.

The implementation, functional features and advantages of the objects of the present invention will be further explained with reference to the accompanying drawings.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

In addition, the technical solutions in the embodiments of the present invention may be combined with each other, but it must be based on the realization of those skilled in the art, and when the technical solutions are contradictory or cannot be realized, such a combination of technical solutions should not be considered to exist, and is not within the protection scope of the present invention.

The drugs/reagents used are all commercially available without specific mention.

The invention provides a synthesis method of a SiBCN ceramic precursor, which comprises the following steps:

s5: and after the addition is finished, continuously stirring at room temperature for 10-20 h, and then carrying out reduced pressure distillation for 10-20 h under the condition of a constant-temperature water bath at the temperature of 60 ℃ to remove the solvent, thereby obtaining the SiBCN ceramic precursor.

Preferably, the organosilicon compound is a small molecule containing two or more amine groups and also containing a silicon group.

Preferably, the organosilicon compound is one of 1, 3-bis (aminopropyl) tetramethyldisiloxane, [3- (trimethoxysilyl) propyl ] ethylenediamine and octamethylcyclotetrasilazane.

Preferably, the structural formula of the 1, 3-bis (aminopropyl) tetramethyldisiloxane is as follows:

the structural formula of the [3- (trimethoxysilyl) propyl ] ethylenediamine is as follows:

the structural formula of the octamethylcyclotetrasilazane is as follows:

preferably, in the step S2, the substance amount concentration of the decaborane in the decaborane solution is 0.2-0.6 mol/L;

the mass concentration of the organic silicon compound in the organic silicon compound solution is 0.2-0.6 mol/L. After dispersion, the dispersion is beneficial to stable reaction and avoids over-quick reaction and heat release.

Preferably, in step S3, the inert gas is nitrogen or argon, and the concentration is greater than 99.9%, so as to avoid introducing impurities and ensure the quality of the synthesized product.

Preferably, the inert gas is introduced at a speed of 0.5-2L/min.

Preferably, in the step S4, the adding speed of the organic silicon compound solution is 5-20 mL/min. The reaction speed is controlled to make the reaction smooth.

The invention also provides a SiBCN ceramic precursor synthesized by the synthesis method.

Preferably, the SiBCN ceramic precursor has the number average molecular weight of 2053-4037, the weight average molecular weight of 2279-9090 and the molecular weight dispersity of 1.11-2.25, can be dissolved in tetrahydrofuran, N-dimethylformamide and dimethyl sulfoxide, and is heated to 1000 ℃ in an inert atmosphere so that the mass retention rate (ceramic yield) reaches over 75 wt%.

Example 1

The embodiment provides a method for synthesizing a SiBCN ceramic precursor, which comprises the following steps:

s1: 0.1mol of decaborane and 0.1mol of 1, 3-bis (aminopropyl) tetramethyldisiloxane are weighed out.

S2: dissolving decaborane in anhydrous tetrahydrofuran to obtain a decaborane solution; the substance amount concentration of decaborane in the decaborane solution was 0.2 mol/L.

Dissolving 1, 3-bis (aminopropyl) tetramethyldisiloxane in anhydrous tetrahydrofuran to obtain an organic silicon compound solution; the mass concentration of 1, 3-bis (aminopropyl) tetramethyldisiloxane in the organosilicon compound solution was 0.2 mol/L.

S3: selecting a reaction kettle with a stirrer, replacing air in the reaction kettle with nitrogen (the introduction speed is 0.5L/min), and adding decaborane solution into the reaction kettle;

s4: under the condition of stirring, the organosilicon compound solution is added into the reaction kettle at the speed of 20 mL/min.

S5: and after the addition is finished, continuously stirring for 10 hours at room temperature, and then carrying out reduced pressure distillation for 20 hours under the condition of a constant-temperature water bath at the temperature of 60 ℃ to remove the solvent, thereby obtaining a powdery solid, namely the SiBCN ceramic precursor.

The SiBCN ceramic precursor synthesized in this example had B, C, N contents of 14.6 wt%, 24.5 wt%, and 3.6 wt%, respectively, a number average molecular weight of 2053, a weight average molecular weight of 2279, and a molecular weight dispersion of 1.11, and was soluble in tetrahydrofuran, N-dimethylformamide, and dimethylsulfoxide. The infrared spectrogram, the XPS elemental analysis spectrogram and the thermal weight loss curve of the SiBCN ceramic precursor are respectively shown in figures 1-3. As can be seen from the IR spectrum of FIG. 1, the SiBCN ceramic precursor contains C-H bonds and Si-C bonds for the alkyl groups as well as B-H, B-N, Si-O-Si chemical bonds. From the XPS spectrum of fig. 2, it is also shown that the SiBCN ceramic precursor mainly contains Si, B, C, N and O elements. The thermal weight loss plot of fig. 3 shows that the ceramic yield of the SiBCN ceramic precursor was 82.9 wt%.

Example 2

s1: 0.1mol of decaborane and 0.1mol of [3- (trimethoxysilyl) propyl ] ethylenediamine were weighed out.

S2: dissolving decaborane in anhydrous tetrahydrofuran to obtain a decaborane solution; the substance amount concentration of decaborane in the decaborane solution was 0.4 mol/L.

Dissolving [3- (trimethoxysilyl) propyl ] ethylenediamine in anhydrous tetrahydrofuran to obtain an organic silicon compound solution; the amount concentration of the substance of [3- (trimethoxysilyl) propyl ] ethylenediamine in the organosilicon compound solution was 0.6 mol/L.

S3: selecting a reaction kettle with a stirrer, replacing air in the reaction kettle with nitrogen (the introduction speed is 1.0L/min), and adding decaborane solution into the reaction kettle;

s4: under the condition of stirring, the organosilicon compound solution is added into the reaction kettle at the speed of 10 mL/min.

S5: after the addition, stirring is continued for 16h at room temperature, and then the solvent is removed by vacuum distillation for 16h under the condition of constant temperature water bath at 60 ℃ to obtain powdery solid, namely the SiBCN ceramic precursor.

The SiBCN ceramic precursor synthesized in this example had B, C, N contents of 17.2 wt%, 29.2 wt%, and 4.3 wt%, respectively, a number average molecular weight of 4037, a weight average molecular weight of 9090, and a molecular weight dispersion of 2.25, and was soluble in tetrahydrofuran, N-dimethylformamide, and dimethylsulfoxide. The ceramic yield of the SiBCN ceramic precursor was 81.8 wt%. As can be seen from fig. 4, the chemical structure of the SiBCN ceramic precursor synthesized in this example is similar to that of the SiBCN precursor synthesized in example 1.

Example 3

s1: 0.1mol of decaborane and 0.1mol of octamethylcyclotetrasilazane were weighed out.

S2: dissolving decaborane in anhydrous tetrahydrofuran to obtain a decaborane solution; the substance amount concentration of decaborane in the decaborane solution was 0.6 mol/L.

Dissolving octamethylcyclotetrasilazane in anhydrous tetrahydrofuran to obtain an organosilicon compound solution; the substance content of octamethylcyclotetrasilazane in the organosilicon compound solution was 0.4 mol/L.

S3: selecting a reaction kettle with a stirrer, replacing air in the reaction kettle with nitrogen (the introduction speed is 2.0L/min), and adding decaborane solution into the reaction kettle;

s4: under the condition of stirring, the organosilicon compound solution is added into the reaction kettle at the speed of 5 mL/min.

S5: and after the addition is finished, continuously stirring at room temperature for 20h, and then carrying out reduced pressure distillation for 10h under the condition of a constant-temperature water bath at 60 ℃ to remove the solvent, thus obtaining a powdery solid, namely the SiBCN ceramic precursor.

The SiBCN ceramic precursor synthesized in this example had B, C, N contents of 27.6 wt%, 18.5 wt%, and 12.3 wt%, respectively, a number average molecular weight of 2712, a weight average molecular weight of 3895, and a molecular weight dispersion of 1.43, and was soluble in tetrahydrofuran, N-dimethylformamide, and dimethylsulfoxide, and had a ceramic yield of 76.9 wt%. As can be seen in fig. 4, the chemical structure of the SiBCN ceramic precursor synthesized in this example is similar to that of the SiBCN precursor synthesized in example 1.

The above description is only a preferred embodiment of the present invention, and is not intended to limit the scope of the present invention, and all modifications and equivalents of the present invention, which are made by the contents of the present specification and the accompanying drawings, or directly/indirectly applied to other related technical fields, are included in the scope of the present invention.

Claims

1. a synthetic method of SiBCN ceramic precursor, is characterized in that, comprises the following steps:

S1: Weigh decaborane and the organosilicon compound in a ratio of 1:1;

Dissolving the organosilicon compound in anhydrous tetrahydrofuran to obtain an organosilicon compound solution;

S3: choose the reactor with stirring, replace the air in the reactor with an inert gas, then add the decaborane solution to the reactor;

S4: under stirring conditions, add organosilicon compound solution to the reactor;

S5: After the feeding is completed, continue to stir at room temperature for 10-20 hours, and then distill under reduced pressure for 10-20 hours under the condition of a constant temperature water bath at 60°C to obtain a SiBCN ceramic precursor.

2 . The synthesis method of claim 1 , wherein the organosilicon compound is a small molecule containing two or more amine groups and simultaneously containing silicon groups. 3 .

3. The synthetic method of claim 2, wherein the organosilicon compound is 1,3-bis(aminopropanyl)tetramethyldisilazane, [3-(trimethoxysilyl)propane] one of ethylenediamine and octamethylcyclotetrasilazane.

4. synthetic method as claimed in claim 3, is characterized in that, the structural formula of described 1,3-bis (aminopropanyl) tetramethyldisilazane is as follows:

The structural formula of the [3-(trimethoxysilyl)propyl]ethylenediamine is as follows:

The structural formula of described octamethylcyclotetrasilazane is as follows:

5. The synthetic method of claim 1, wherein, in step S2, the substance concentration of decaborane in the decaborane solution is 0.2 to 0.6 mol/L;

The substance concentration of the organosilicon compound in the organosilicon compound solution is 0.2-0.6 mol/L.

6. The synthesis method of claim 1, wherein in step S3, the inert gas is nitrogen or argon, and the concentration is greater than 99.9%.

7 . The synthesis method of claim 1 , wherein the inert gas is introduced at a rate of 0.5 to 2 L/min. 8 .

8 . The synthesis method of claim 1 , wherein, in step S4 , the addition rate of the organosilicon compound solution is 5-20 mL/min. 9 .

9 . A SiBCN ceramic precursor, characterized in that it is synthesized by the synthesis method of any one of claims 1 to 8 . 10 .

10. The SiBCN ceramic precursor according to claim 9, wherein the SiBCN ceramic precursor has a number-average molecular weight of 2053-4037, a weight-average molecular weight of 2279-9090, and a molecular weight dispersion of 1.11-2.25. Soluble in tetrahydrofuran, N,N-dimethylformamide and dimethylsulfoxide.