阅读说明：本技术 一种四组元SiHfBC聚合物陶瓷先驱体的制备方法及其应用 (Preparation method and application of four-component SiHfBC polymer ceramic precursor ) 是由 韩文波 吕杨 赵广东 张幸红 王武举 王春霖 于 2021-11-17 设计创作，主要内容包括：一种四组元SiHfBC聚合物陶瓷先驱体的制备方法及其应用,本发明涉及有机高分子材料领域,具体涉及一种陶瓷先驱体的制备方法及其应用。本发明要解决现有多元陶瓷先驱体含氧量过高的技术问题。方法：将四氯化铪溶解在四氢呋喃溶剂,制备先驱体溶液；加入甲基乙烯基二氯硅烷和硼烷二甲硫醚反应；升温加热,进行交联反应；固化处理。将所述一种四组元SiHfBC聚合物陶瓷先驱体进行热解制备得到SiHfBC聚合物陶瓷。本发明反应过程,可有效地调整SiHfBC聚合物陶瓷先驱体的结构,保证先驱体中元素分布的均匀性。通过固化反应脱去小分子形成高聚物,最终经过热解形成共价键连接稳定的SiHfBC聚合物陶瓷。本发明用于制备SiHfBC聚合物陶瓷。(The invention discloses a preparation method and application of a four-component SiHfBC polymer ceramic precursor, relates to the field of organic high polymer materials, and particularly relates to a preparation method and application of a ceramic precursor. The invention aims to solve the technical problem that the oxygen content of the prior multi-component ceramic precursor is too high. The method comprises the following steps: dissolving hafnium tetrachloride in a tetrahydrofuran solvent to prepare a precursor solution; adding methyl vinyl dichlorosilane and borane dimethylsulfide for reaction; heating to carry out crosslinking reaction; and (5) curing treatment. And pyrolyzing the four-component SiHfBC polymer ceramic precursor to prepare the SiHfBC polymer ceramic. The reaction process of the invention can effectively adjust the structure of the SiHfBC polymer ceramic precursor and ensure the uniformity of element distribution in the precursor. Micromolecules are removed through a curing reaction to form a high polymer, and finally the SiHfBC polymer ceramic with stable covalent bond connection is formed through pyrolysis. The method is used for preparing the SiHfBC polymer ceramic.)

1. A preparation method of a four-component SiHfBC polymer ceramic precursor is characterized by comprising the following steps:

firstly, dissolving hafnium tetrachloride in tetrahydrofuran solvent, pouring into a three-neck bottle, controlling the temperature by adopting an oil bath pan, and introducing N₂Stirring to obtain a precursor solution A;

secondly, adding methyl vinyl dichlorosilane and borane dimethylsulfide into the precursor solution A obtained in the first step through a constant-pressure separating funnel respectively, stirring for reaction, and controlling the temperature of a condenser pipe by using a circulating cooling water device to obtain a precursor solution B;

thirdly, heating the precursor solution B obtained in the second step to carry out crosslinking reaction to obtain a precursor solution C;

and fourthly, curing the precursor solution C obtained in the third step to obtain the four-component SiHfBC polymer ceramic precursor.

2. The method for preparing a four-component SiHfBC polymer ceramic precursor as claimed in claim 1, wherein the molar ratio of hafnium tetrachloride to tetrahydrofuran in step one is 1: 200.

3. The preparation method of the four-component SiHfBC polymer ceramic precursor as claimed in claim 1, wherein the temperature of the oil bath pot is controlled to be 10-25 ℃ and the stirring time is controlled to be 0.3-0.5 h.

4. The preparation method of the four-component SiHfBC polymer ceramic precursor as claimed in claim 1, wherein the molar ratio of the methylvinyldichlorosilane to the hafnium tetrachloride in the second step is 10 (1-4), and the molar ratio of the methylvinyldichlorosilane to the borane dimethylsulfide is 10 (2-8).

5. The preparation method of the four-component SiHfBC polymer ceramic precursor as claimed in claim 1, wherein magnetic stirring is adopted in the second step, and the stirring time is controlled to be 0.5-1 h.

6. The preparation method of the four-component SiHfBC polymer ceramic precursor as claimed in claim 1, wherein the temperature of the condenser tube in the second step is controlled to be-10-0 ℃.

7. The preparation method of the four-component SiHfBC polymer ceramic precursor as claimed in claim 1, wherein in the third step, the temperature rise rate is controlled to 10 ℃/h, the temperature is raised to 100 ℃, and the temperature is maintained for the crosslinking reaction for 2-3 h.

8. The preparation method of the four-component SiHfBC polymer ceramic precursor as claimed in claim 1, wherein the four-component SiHfBC polymer ceramic precursor is subjected to curing treatment in the fourth step, wherein the initial temperature is 120 ℃, the heating rate is controlled to be 20 ℃/h, the temperature is increased to 200 ℃, and the temperature holding time is 6-10 h.

9. The use of a four-component SiHfBC polymer ceramic precursor according to claim 1, wherein said four-component SiHfBC polymer ceramic precursor is used as a ceramic precursor to produce a SiHfBC polymer ceramic.

10. The use of a four-component SiHfBC polymer ceramic precursor according to claim 9, wherein the four-component SiHfBC polymer ceramic precursor is pyrolyzed to produce a SiHfBC polymer ceramic; the ceramic yield is 41-68%;

the pyrolysis process comprises the following steps: controlling the heating rate to be 5 ℃/min, heating to 900-1800 ℃, keeping the temperature for 1-3 h, then controlling the cooling rate to be 5 ℃/min, and cooling to the room temperature.

Technical Field

The invention relates to the field of organic polymer materials, in particular to a preparation method and application of a ceramic precursor.

Background

The ultrahigh-temperature ceramic material is an important member of a high-temperature material family, and has the characteristics of moderate density, moderate strength, excellent ablation resistance and the like. However, with HfB₂Or HfC, is difficult to fully meet the requirements of practical engineering applications due to its inherent brittleness and low reliability. Aiming at the problems, the preparation process of the continuous fiber toughened composite material can greatly improve the damage tolerance and reliability of the material, meet the requirement of long-term high-temperature oxidation resistance and has good engineering application prospect. However, due to the great difference of the physicochemical properties of different kinds of ceramics, it is difficult to realize the uniform dispersion of the ultra-high temperature multi-phase ceramic powder in the matrix, which restricts the synergistic matching of the oxidation resistance and the high temperature resistance of the multi-component ceramic phase. And the Polymer Derived Ceramics (PDCs) can realize the molecular dispersion of each component and have good structural designability and functional characteristics. Therefore, its application in many critical areas is receiving a wide range of attention, especially in high temperature resistant materials (ceramic fibers, ceramic matrix composites, thermal barrier coatings and ceramic foams/aerogels).

As early as the early 60's of the 20 th century, processes for the preparation of silicone polymers to silicon-based ceramics have been proposed, resulting in polymer-derived ceramics. Then, researchers have prepared silicon nitride/SiC ceramics and SiC ceramic fibers with small diameters by thermal decomposition of polysiloxane precursors. Given the great potential of such preformed polymers in material science, a number of precursor polymers for the synthesis of silicon-based ceramics are being developed. The key phenomenon of polymer conversion to ceramic during pyrolysis provides an important avenue for developing new silicon-based ceramics, such as coatings/films, small diameter fibers, ceramic matrix composites, and non-oxide ceramics that are stable below 2000 ℃. Therefore, the synthesis of the precursor meeting the use requirement is a crucial step in the preparation of the high-performance ceramic matrix composite.

At present, ceramic precursors such as SiBOC, SiAlOC, SiZrOC and the like are prepared by scientific research institutions, but the oxide content in the ceramic matrix composite material with multi-component is too high, the structure of the matrix becomes loose and porous under the oxidation environment higher than 1600 ℃, and the oxidation resistance and the mechanical property are greatly reduced. If the prepared carbon fiber toughened ceramic matrix composite contains a large amount of oxygen, the damage to the fiber is great under the oxidation environment with higher temperature, so that the preparation method of the oxygen-free SiHfBC ceramic precursor is necessary to be researched.

Disclosure of Invention

The invention provides a preparation method of a four-component SiHfBC polymer ceramic precursor, aiming at solving the technical problem that the oxygen content of the existing multi-component ceramic precursor is too high.

A preparation method of a four-component SiHfBC polymer ceramic precursor comprises the following steps:

firstly, dissolving hafnium tetrachloride in tetrahydrofuran solvent, pouring into a three-neck bottle, controlling the temperature by adopting an oil bath pan, and introducing N₂Stirring to obtain a precursor solution A;

secondly, adding methyl vinyl dichlorosilane and borane dimethylsulfide into the precursor solution A obtained in the first step through a constant-pressure separating funnel respectively, stirring for reaction, and controlling the temperature of a condenser pipe by using a circulating cooling water device to obtain a precursor solution B;

thirdly, heating the precursor solution B obtained in the second step to carry out crosslinking reaction to obtain a precursor solution C;

and fourthly, curing the precursor solution C obtained in the third step to obtain the four-component SiHfBC polymer ceramic precursor.

The four-component SiHfBC polymer ceramic precursor is used as a ceramic precursor for preparing SiHfBC polymer ceramic.

Pyrolyzing the four-component SiHfBC polymer ceramic precursor to prepare SiHfBC polymer ceramic; the ceramic yield is 42-61%;

the pyrolysis process comprises the following steps: controlling the heating rate to be 5 ℃/min, heating to 900-1800 ℃, keeping the temperature for 1-3 h, then controlling the cooling rate to be 5 ℃/min, and cooling to the room temperature.

The invention aims to synthesize a SiHfBC polymer ceramic precursor, and mainly solves the problem that elements such as Hf and the like are crosslinked in a Si-based skeleton in the curing process, namely Si, Hf, B and C are connected through covalent bonds to form a precursor polymer containing a large amount of elements such as Si, Hf, B and C, so that a preparation scheme of the SiHfBC polymer ceramic precursor is obtained. In the process, the structure of the SiHfBC polymer ceramic precursor can be effectively adjusted through the molecular level design of the precursor, and the uniformity of element distribution in the precursor is ensured. And then removing small molecules from the precursor through a curing reaction to form a high polymer, and finally forming SiHfBC polymer ceramic with stable covalent bond connection through pyrolysis.

The invention has the beneficial effects that:

in the SiHfBC polymer ceramic precursor prepared by the method, Si, Hf, B and C are connected through covalent bonds to form a high-molecular precursor structure which is stable through chemical bonding. Precursor polymers with different ceramic yields can be obtained according to different mole ratios of the added reagents. The ceramic yield of the SiHfBC precursor prepared according to the steps is 42-61%, and the SiHfBC polymer ceramic precursor of 40g is pyrolyzed at high temperature to obtain the SiHfBC ceramic powder of 16-24 g.

The method is used for preparing the SiHfBC polymer ceramic.

Drawings

FIG. 1 is a FTIR picture of a four-component SiHfBC polymer ceramic precursor prepared in example one and example three, wherein a represents example one and c represents example three;

FIG. 2 is an XRD plot of a SiHfBC polymer ceramic prepared by pyrolysis of a four-component SiHfBC polymer ceramic precursor as described in example one, whereinRepresents SiC, represents HfB₂；

FIG. 3 is a graph of elemental distribution of a scanning transmission electron image of SiHfBC polymer ceramic prepared by pyrolysis of a four-component SiHfBC polymer ceramic precursor according to example three; (a) representing HAADF image of the SiHfBC polymer ceramic, (B) representing Si element surface scanning image of the SiHfBC polymer ceramic, (C) representing Hf element surface scanning image of the SiHfBC polymer ceramic, (d) representing BF image of the SiHfBC polymer ceramic, (e) representing B element surface scanning image of the SiHfBC polymer ceramic, and (f) representing C element surface scanning image of the SiHfBC polymer ceramic;

fig. 4 is a TG picture of a four-component SiHfBC polymer ceramic precursor prepared in example one and example two, wherein 1 represents example one and 2 represents example two.

Detailed Description

The technical solution of the present invention is not limited to the specific embodiments listed below, and includes any combination of the specific embodiments.

The first embodiment is as follows: the preparation method of the four-component SiHfBC polymer ceramic precursor comprises the following steps:

firstly, dissolving hafnium tetrachloride in tetrahydrofuran solvent, pouring into a three-neck bottle, controlling the temperature by adopting an oil bath pan, and introducing N₂Stirring to obtain a precursor solution A;

secondly, adding methyl vinyl dichlorosilane and borane dimethylsulfide into the precursor solution A obtained in the first step through a constant-pressure separating funnel respectively, stirring for reaction, and controlling the temperature of a condenser pipe by using a circulating cooling water device to obtain a precursor solution B;

thirdly, heating the precursor solution B obtained in the second step to carry out crosslinking reaction to obtain a precursor solution C;

and fourthly, curing the precursor solution C obtained in the third step to obtain the four-component SiHfBC polymer ceramic precursor.

The second embodiment is as follows: the first difference between the present embodiment and the specific embodiment is: step one, the molar ratio of the hafnium tetrachloride to the tetrahydrofuran is 1: 200. The rest is the same as the first embodiment.

The third concrete implementation mode: the present embodiment differs from the first or second embodiment in that: in the first step, the temperature of the oil bath pot is controlled to be 10-25 ℃, and the stirring time is controlled to be 0.3-0.5 h. The other embodiments are the same as the first embodiment or the second embodiment.

The fourth concrete implementation mode: the difference between this embodiment mode and one of the first to third embodiment modes is: and in the second step, the molar ratio of the methyl vinyl dichlorosilane to the hafnium tetrachloride is 10 (1-4), and the molar ratio of the methyl vinyl dichlorosilane to the borane dimethylsulfide is 10 (2-8). The others are the same as one of the first to third embodiments.

The fifth concrete implementation mode: the difference between this embodiment and one of the first to fourth embodiments is: and step two, magnetic stirring is adopted, and the stirring time is controlled to be 0.5-1 h. The others are the same as one of the first to fourth embodiments.

The sixth specific implementation mode: the difference between this embodiment and one of the first to fifth embodiments is: and step two, controlling the temperature of the condensation pipe to be-10-0 ℃. The others are the same as one of the first to fifth embodiments.

The seventh embodiment: the difference between this embodiment and one of the first to sixth embodiments is: and step three, controlling the heating rate to be 10 ℃/h, heating to 100 ℃, and keeping the temperature to perform crosslinking reaction for 2-3 h. The others are the same as one of the first to sixth embodiments.

The specific implementation mode is eight: the present embodiment differs from one of the first to seventh embodiments in that: and step four, curing treatment, wherein the initial temperature is 120 ℃, the heating rate is controlled to be 20 ℃/h, the temperature is increased to 200 ℃, and the temperature holding time is 6-10 h. The others are the same as one of the first to seventh embodiments.

The specific implementation method nine: the application of the four-component SiHfBC polymer ceramic precursor is used for preparing SiHfBC polymer ceramic by taking the four-component SiHfBC polymer ceramic precursor as a ceramic precursor.

The detailed implementation mode is ten: the present embodiment differs from the ninth embodiment in that: pyrolyzing the four-component SiHfBC polymer ceramic precursor to prepare SiHfBC polymer ceramic; the ceramic yield is 41-68%;

the pyrolysis process comprises the following steps: controlling the heating rate to be 5 ℃/min, heating to 900-1800 ℃, keeping the temperature for 1-3 h, then controlling the cooling rate to be 5 ℃/min, and cooling to the room temperature. The rest is the same as the embodiment nine.

The following examples were used to demonstrate the beneficial effects of the present invention:

the first embodiment is as follows:

the preparation method of the four-component SiHfBC polymer ceramic precursor provided by the embodiment comprises the following steps:

firstly, dissolving hafnium tetrachloride in tetrahydrofuran solvent at room temperature, pouring into a three-neck flask, utilizing a circulating cooling water device, adopting an oil bath pan to control the temperature to be 10 ℃, and introducing N at the flow rate of 50mL/min₂Magnetically stirring for 0.3h to obtain a precursor solution A; the molar ratio of the hafnium tetrachloride to the tetrahydrofuran is 1: 200;

secondly, adding methyl vinyl dichlorosilane and borane dimethylsulfide into the precursor solution A obtained in the first step through a constant-pressure separating funnel respectively, controlling the temperature of an oil bath kettle to be 20 ℃, carrying out magnetic stirring for reaction for 1 hour, and controlling the temperature of a condenser pipe to be-5 ℃ by utilizing a circulating cooling water device to obtain a precursor solution B; the molar ratio of the methylvinyldichlorosilane to the hafnium tetrachloride is 10:1, and the molar ratio of the methylvinyldichlorosilane to the borane dimethylsulfide is 10: 2;

thirdly, heating the oil bath kettle, controlling the heating rate to be 10 ℃/h, heating the precursor solution B obtained in the second step to 100 ℃, closing the circulating cooling water device, heating and keeping the temperature to be 100 ℃, and carrying out crosslinking reaction for 2h to obtain a precursor solution C;

and fourthly, curing the precursor solution C obtained in the third step, wherein the initial temperature is 120 ℃, the heating rate is controlled to be 20 ℃/h, the temperature is increased to 200 ℃, and the temperature holding time is 6h, so that the four-component SiHfBC polymer ceramic precursor is obtained.

Pyrolyzing the four-component SiHfBC polymer ceramic precursor to prepare SiHfBC polymer ceramic;

the pyrolysis process comprises the following steps: controlling the heating rate to be 5 ℃/min, heating to 1800 ℃, keeping the temperature for 1h, then controlling the cooling rate to be 5 ℃/min, and cooling to the room temperature.

Example two:

the preparation method of the four-component SiHfBC polymer ceramic precursor provided by the embodiment comprises the following steps:

firstly, dissolving hafnium tetrachloride in tetrahydrofuran solvent at room temperature, pouring into a three-neck flask, utilizing a circulating cooling water device, adopting an oil bath pan to control the temperature to be 10 ℃, and introducing N at the flow rate of 50mL/min₂Magnetically stirring for 0.3h to obtain a precursor solution A; the molar ratio of the hafnium tetrachloride to the tetrahydrofuran is 1: 200;

secondly, adding methyl vinyl dichlorosilane and borane dimethylsulfide into the precursor solution A obtained in the first step through a constant-pressure separating funnel respectively, controlling the temperature of an oil bath kettle to be 20 ℃, carrying out magnetic stirring for reaction for 1 hour, and controlling the temperature of a condenser pipe to be 0 ℃ by utilizing a circulating cooling water device to obtain a precursor solution B; the molar ratio of the methylvinyldichlorosilane to the hafnium tetrachloride is 10:2, and the molar ratio of the methylvinyldichlorosilane to the borane dimethylsulfide is 10: 4;

thirdly, heating the oil bath kettle, controlling the heating rate to be 10 ℃/h, heating the precursor solution B obtained in the second step to 100 ℃, closing the circulating cooling water device, heating and keeping the temperature to be 100 ℃, and carrying out crosslinking reaction for 2h to obtain a precursor solution C;

and fourthly, curing the precursor solution C obtained in the third step, wherein the initial temperature is 120 ℃, the heating rate is controlled to be 20 ℃/h, the temperature is increased to 200 ℃, and the temperature holding time is 8h, so that the four-component SiHfBC polymer ceramic precursor is obtained.

Pyrolyzing the four-component SiHfBC polymer ceramic precursor to prepare SiHfBC polymer ceramic;

the pyrolysis process comprises the following steps: controlling the heating rate to be 5 ℃/min, heating to 1800 ℃, keeping the temperature for 2h, then controlling the cooling rate to be 5 ℃/min, and cooling to the room temperature.

Example three:

the preparation method of the four-component SiHfBC polymer ceramic precursor provided by the embodiment comprises the following steps:

firstly, dissolving hafnium tetrachloride in tetrahydrofuran solvent at room temperature, pouring into a three-neck flask, and utilizingThe circulating cooling water device adopts an oil bath pan to control the temperature to be 10 ℃ and the flow rate to be 50mL/min and then N is introduced₂Magnetically stirring for 0.3h to obtain a precursor solution A; the molar ratio of the hafnium tetrachloride to the tetrahydrofuran is 1: 200;

secondly, adding methyl vinyl dichlorosilane and borane dimethylsulfide into the precursor solution A obtained in the first step through a constant-pressure separating funnel respectively, controlling the temperature of an oil bath kettle to be 20 ℃, carrying out magnetic stirring for reaction for 1 hour, and controlling the temperature of a condenser pipe to be-2 ℃ by utilizing a circulating cooling water device to obtain a precursor solution B; the molar ratio of the methylvinyldichlorosilane to the hafnium tetrachloride is 10:3, and the molar ratio of the methylvinyldichlorosilane to the borane dimethylsulfide is 10: 6;

thirdly, heating the oil bath kettle, controlling the heating rate to be 10 ℃/h, heating the precursor solution B obtained in the second step to 100 ℃, closing the circulating cooling water device, heating and keeping the temperature to be 100 ℃, and carrying out crosslinking reaction for 2h to obtain a precursor solution C;

and fourthly, curing the precursor solution C obtained in the third step, wherein the initial temperature is 120 ℃, the heating rate is controlled to be 20 ℃/h, the temperature is increased to 200 ℃, and the temperature holding time is 6h, so that the four-component SiHfBC polymer ceramic precursor is obtained.

Pyrolyzing the four-component SiHfBC polymer ceramic precursor to prepare SiHfBC polymer ceramic;

the pyrolysis process comprises the following steps: controlling the heating rate to be 5 ℃/min, heating to 1800 ℃, keeping the temperature for 3h, then controlling the cooling rate to be 5 ℃/min, and cooling to the room temperature.

The four-component SiHfBC polymer ceramic precursors prepared in the examples were tested:

FIG. 1 is a FTIR picture of a four-component SiHfBC polymer ceramic precursor prepared in example one and example three, wherein a represents example one and c represents example three; from the figure, it can be confirmed that Hf element and B element are crosslinked in Si-based skeleton, and four elements on molecular chain segment are integrally connected together, which provides important precondition for subsequent experiment development and ensures to obtain expected result.

FIG. 2 shows an embodiment 1The four-component SiHfBC polymer ceramic precursor is pyrolyzed to prepare an XRD picture of the SiHfBC polymer ceramic, whereinRepresents SiC, represents HfB₂(ii) a It can be seen that only HfB is present in the figure₂And the characteristic peak of SiC, no other miscellaneous peak exists, which indicates that the oxygen in the ceramic matrix is completely removed and HfB is prepared₂The final purpose of the invention for preparing the SiHfBC polymer ceramic precursor is to obtain HfB with higher purity₂-SiC ceramic, such in situ generated HfB₂the-SiC ceramic has higher sintering activity and more excellent high-temperature resistance and oxidation resistance, and has wider engineering application.

FIG. 3 is a graph of elemental distribution of a scanning transmission electron image of a SiHfBC polymer ceramic prepared by pyrolysis of a four-component SiHfBC polymer ceramic precursor according to a third example, wherein (a) represents a HAADF image of the SiHfBC polymer ceramic, (B) represents a Si elemental profile of the SiHfBC polymer ceramic, (C) represents a Hf elemental profile of the SiHfBC polymer ceramic, (d) represents a BF image of the SiHfBC polymer ceramic, (e) represents a B elemental profile of the SiHfBC polymer ceramic, and (f) represents a C elemental profile of the SiHfBC polymer ceramic; (ii) a It can be seen from the figure that the distribution of each element in the SiHfBC polymer ceramic is very uniform, the dispersibility is good, and the HfB generated in situ₂the-SiC crystal grains have higher sintering activity.

FIG. 4 is a TG picture of the four-component SiHfBC polymer ceramic precursors prepared in the first and second examples, and it can be seen from the graph that the pyrolysis process of the SiHfBC polymer ceramic precursors is roughly divided into 3 stages, the pyrolysis temperature is decreased by about 25% at 20-260 deg.C, decreased by about 13% at 260-800 deg.C, decreased by about 1% at 800-1400 deg.C, and the ceramic yield is increased with the increase of Hf content, and the final ceramic yield is 61% and 42%, respectively.