Ablation-resistant tantalum ethoxide modified polyborosilazane resin as well as preparation method and application thereof

Abstract

The invention provides ablation-resistant tantalum ethoxide modified polyborosilazane resin as well as a preparation method and application of the ablation-resistant tantalum ethoxide modified polyborosilazane resin. The preparation method comprises the following steps: S1, reacting boron trichloride, methyl dichlorosilane and hexamethyldisilazane under the protection of an inert atmosphere to obtain a polyborosilazane fluid; s2, under the protection of inert atmosphere, reacting the polyborosilazane fluid, divinyl benzene and tantalum ethoxide in the presence of a catalyst to obtain a tantalum ethoxide modified polyborosilazane oligomer fluid; s3, under the protection of inert atmosphere, heating and curing the tantalum ethoxide modified polyborosilazane oligomer fluid to obtain the ablation-resistant resin. The tantalum ethoxide modified polyborosilazane resin disclosed by the invention has a high crosslinking degree and shows excellent high temperature resistance and oxidation resistance.

Description

Technical Field

[0001] The present invention relates to the field of chemical engineering technology, and specifically to an ethanol tantalum modified polyborosilazane resin with ablation resistance, its preparation method and application. Background Technique

[0002] On the surfaces of aircraft, rocket combustion chambers and nozzles, as well as instrument surfaces in high-temperature environments, a layer of thermal protection material is required to protect the integrity of their internal structures and enable the normal operation of the engine. Therefore, in recent years, ablation-resistant materials have been widely used in the high-speed protection of the internal structures and instruments of spacecraft and the military industry, especially in extremely high-temperature situations. Polyborosilazane is a type of silicon-containing polymer with excellent high-temperature resistance and oxidation resistance. For a long time, the research on polyborosilazane has mainly focused on the design and application as a ceramic precursor, and there has been less research on using polyborosilazane as a resin. With the increasing demand for ablation-resistant materials in the aerospace and military industries in recent years, polyborosilazane resin with excellent high-temperature resistance and oxidation resistance has great application prospects as a thermal protection material in extreme environments. However, traditional polyborosilazane resins have a low cross-linking degree and limited high-temperature resistance, and still need to be further modified to improve their performance. Summary of the Invention

[0003] To solve the problems of the above-mentioned prior art, the present invention provides an ethanol tantalum modified polyborosilazane resin with ablation resistance, its preparation method and application. The ethanol tantalum modified polyborosilazane resin of the present invention has a high cross-linking degree and exhibits excellent high-temperature resistance and oxidation resistance.

[0004] The present invention is achieved through the following technical solutions: In the first aspect, the present invention provides a preparation method of an ethanol tantalum modified polyborosilazane resin with ablation resistance, including; S1, under the protection of an inert atmosphere, react boron trichloride, methyldichlorosilane and hexamethyldisilazane to obtain a polyborosilazane fluid; S2, under the protection of an inert atmosphere, react the polyborosilazane fluid, divinylbenzene and ethanol tantalum in the presence of a catalyst to obtain an ethanol tantalum modified polyborosilazane oligomer fluid; S3, under the protection of an inert atmosphere, heat and cure the ethanol tantalum modified polyborosilazane oligomer fluid to obtain an ablation-resistant resin.

[0005] Preferably, S1 is specifically: mix boron trichloride, methyldichlorosilane and hexamethyldisilazane under a low-temperature bath condition, and then heat for reaction.

[0006] Furthermore, the temperature of the low-temperature bath is -40~-10 °C.

[0007] Further, the heating for reaction specifically is: first, raise the temperature to 120 °C to 150 °C, react for 3 to 6 h, then raise the temperature to 230 to 260 °C, and react for 2 to 4 h.

[0008] Preferably, in S2, the mass ratio of polyborosilazane fluid, divinylbenzene, and tantalum ethoxide is 1:(0.5 to 2):(0.25 to 1).

[0009] Preferably, in S2, the catalyst is Karstedt catalyst.

[0010] Preferably, in S2, the reaction temperature is 40 to 60 °C, and the reaction time is 2 to 6 h.

[0011] Preferably, in S3, the curing temperature is 300 to 600 °C, and the curing time is 2 to 5 h.

[0012] In the second aspect, the present invention provides a char-resistant tantalum ethoxide modified polyborosilazane resin obtained by the preparation method as described above.

[0013] In the third aspect, the present invention provides the application of the char-resistant tantalum ethoxide modified polyborosilazane resin as a thermal protection material.

[0014] Compared with the prior art, the present invention has the following beneficial effects: The present invention provides a preparation method of a char-resistant tantalum ethoxide modified polyborosilazane resin. The preparation method first uses boron trichloride, methyldichlorosilane, and hexamethyldisilazane as raw materials to prepare polyborosilazane fluid; then adds a divinylbenzene crosslinking agent, a tantalum ethoxide modifier, and a catalyst to the above polyborosilazane fluid and mixes them evenly to obtain a tantalum ethoxide modified polyborosilazane oligomer fluid, and finally obtains a char-resistant resin material through high-temperature curing. This method introduces tantalum element into the polyborosilazane resin. The introduction of tantalum can improve the high-temperature resistance and antioxidant properties of the polyborosilazane resin; meanwhile, the crosslinking agent divinylbenzene is used. Divinylbenzene is a chemical molecule with both vinyl and benzene ring groups. Introducing divinylbenzene into the resin oligomer can increase the crosslinking degree, high-temperature resistance, and hybridization of the product.

[0015] The tantalum ethoxide modified polyborosilazane resin prepared by the present invention has a high crosslinking degree, exhibits excellent high-temperature stability and antioxidant properties, can be applied to thermal protection materials in extremely high-temperature occasions, and has a very broad application prospect in high-tech fields such as aerospace. Description of the Drawings

[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0017] Figure 1 Thermogravimetric test data graphs of the resins prepared in Examples 1, 2, 3, 4, and Comparative Examples 1 and 2. Detailed implementation manners

[0018] The following illustrates the implementation manners of the present invention through specific examples. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific implementation manners. Various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0019] It should be noted that the process equipment or devices not specifically noted in the following examples all adopt conventional equipment or devices in the art.

[0020] It should be noted that the terms "include" and "have" and any of their variations are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or device that includes a series of steps or units does not necessarily limit to those clearly listed steps or units, but may include other steps or units not clearly listed or inherent to these processes, methods, products, or devices. Moreover, unless otherwise stated, the numbering of each method step is only a convenient tool for identifying each method step, rather than limiting the arrangement order of each method step or the scope of implementation of the present invention. The change or adjustment of their relative relationships, without substantial change in technical content, should also be regarded as the scope of implementation of the present invention.

[0021] The preparation method of the ablative-resistant tantalum ethoxide modified polyborosilazane resin of the present invention is characterized by including: S1, under the protection of an inert atmosphere, reacting boron trichloride, methyldichlorosilane, and hexamethyldisilazane to obtain a polyborosilazane fluid; S2, under the protection of an inert atmosphere, reacting the polyborosilazane fluid, divinylbenzene, and tantalum ethoxide in the presence of a catalyst to obtain a tantalum ethoxide modified polyborosilazane oligomer fluid; S3, under the protection of an inert atmosphere, heating and curing the tantalum ethoxide modified polyborosilazane oligomer fluid to obtain an ablative-resistant resin.

[0022] The ablative-resistant ethanol tantalum modified polyborosilazane resin of the present invention introduces a crosslinking agent, divinylbenzene. Divinylbenzene is a chemical molecule with both vinyl and benzene ring groups. Introducing divinylbenzene into the resin oligomer can increase the crosslinking degree, high-temperature resistance, and hybridization of the product; and through the reaction with the modifier ethanol tantalum, tantalum element is introduced into the polyborosilazane. The melting point of the metal element tantalum is as high as 3017 °C (second only to tungsten, rhenium, etc.), and it still maintains strength and creep resistance at high temperatures; and the thermal expansion coefficient of tantalum is close to that of glass, with high dimensional stability at high temperatures. The introduction of tantalum can further improve the high-temperature resistance and antioxidant properties of the polyborosilazane resin.

[0023] In a preferred embodiment of the present invention, S1 is: mixing boron trichloride, methyldichlorosilane, and hexamethyldisilazane under a low-temperature bath condition, then first heating to 120 - 150 °C and reacting for 3 - 6 h, and then heating to 230 - 260 °C and reacting for 2 - 4 h.

[0024] Specifically, place the reactor in a low-temperature bath and continuously introduce an inert gas. Inject boron trichloride and methyldichlorosilane into the reactor with a syringe respectively; then add hexamethyldisilazane to a constant-pressure dropping funnel in the same way and slowly drip it into the reactor; then first heat to 120 - 150 °C and react for 3 - 6 h. After the reaction, remove the by-products by decompression; subsequently, heat to 230 - 260 °C and react for 2 - 4 h. The reactants further undergo polycondensation reactions at high temperatures to obtain a turbid viscous polyborosilazane fluid.

[0025] Among them, since the boiling point of boron trichloride is extremely low, in order to prevent the reactants from volatilizing in the initial stage, a low-temperature bath is selected for the reaction, and the temperature of the low-temperature bath is -40 - -10 °C.

[0026] In a preferred embodiment of the present invention, the molar ratio of boron trichloride, methyldichlorosilane, and hexamethyldisilazane is 1:1:4.

[0027] In a preferred embodiment of the present invention, in S2, the mass ratio of the polyborosilazane fluid, divinylbenzene, and ethanol tantalum is 1:(0.5 - 2):(0.25 - 1), and the catalyst is Karstedt catalyst.

[0028] In a preferred embodiment of the present invention, in S2, the reaction temperature is 40 - 60 °C, and the reaction time is 2 - 6 h.

[0029] In a preferred embodiment of the present invention, in S3, the curing temperature is 300 - 600 °C, and the curing time is 2 - 5 h.

[0030] The ablative-resistant ethanol tantalum modified polyborosilazane resin obtained by the present invention has a structure of a highly crosslinked network structure with tantalum-doped boron-nitrogen rings, and the structural formula is as shown in formula (1):

[0031] Formula (1) In Formula (1), both Si-H and N-H are reaction nodes and can react with tantalum ethoxide to attach tantalum metal to the main chain.

[0032] Example 1 (1) Slowly add 23.4 g of boron trichloride, 23.0 g of methyldichlorosilane, and 129.1 g of hexamethyldisilazane dropwise into a three-necked flask placed in a low-temperature bath at -30 °C, and continuously introduce an inert gas. First, slowly heat the reaction system to 130 °C and keep it warm for 5 h. After the reaction, remove the by-products under reduced pressure; then raise the temperature to 240 °C and keep it warm for 3 h. The reactants further undergo a polycondensation reaction at high temperature to obtain a turbid viscous polyborosilazane fluid; (2) Under the protection of a flowing inert gas, add 1 g of the polyborosilazane fluid prepared in step (1), 1 g of divinylbenzene cross-linking agent, and 0.5 g of tantalum ethoxide modifier to a reaction flask. After mixing evenly by magnetic stirring at room temperature for 1 h, then dropwise add a trace amount of Karstedt catalyst, and place it in an oil bath at 40 °C for reaction for 5 h to obtain a tantalum ethoxide-modified polyborosilazane oligomer fluid; (3) Place the tantalum ethoxide-modified polyborosilazane oligomer fluid in step (2) into a mold, put it into a tube furnace, and cure it at a high temperature of 400 °C for 4 h under the protection of an inert gas to obtain an ablative-resistant resin.

[0033] Example 2 (1) Slowly add 23.4 g of boron trichloride, 23.0 g of methyldichlorosilane, and 129.1 g of hexamethyldisilazane dropwise into a three-necked flask placed in a low-temperature bath at -30 °C, and continuously introduce an inert gas. First, slowly heat the reaction system to 120 °C and keep it warm for 6 h. After the reaction, remove the by-products under reduced pressure; then raise the temperature to 230 °C and keep it warm for 4 h. The reactants further undergo a polycondensation reaction at high temperature to obtain a turbid viscous polyborosilazane fluid; (2) Under the protection of a flowing inert gas, add 1 g of the polyborosilazane fluid prepared in step (1), 2 g of divinylbenzene cross-linking agent, and 0.25 g of tantalum ethoxide modifier to a reaction flask. After mixing evenly by magnetic stirring at room temperature for 1 h, then dropwise add a trace amount of Karstedt catalyst, and place it in an oil bath at 60 °C for reaction for 6 h to obtain a tantalum ethoxide-modified polyborosilazane oligomer fluid; (3) Place the tantalum ethoxide-modified polyborosilazane oligomer fluid in step (2) into a mold, put it into a tube furnace, and cure it at a high temperature of 300 °C for 5 h under the protection of an inert gas to obtain an ablative-resistant resin.

[0034] Example 3 (1) Slowly add 23.4 g of boron trichloride, 23.0 g of methyldichlorosilane, and 129.1 g of hexamethyldisilazane dropwise into a three-necked flask placed in a -30 °C low-temperature bath, and continuously introduce an inert gas. First, slowly heat the reaction system to 140 °C and keep it warm for 4 h. After the reaction, remove the by-products by reduced pressure; then raise the temperature to 260 °C and keep it warm for 2 h. The reactants further undergo a polycondensation reaction at high temperature to obtain a turbid viscous polyborosilazane fluid; (2) Under the protection of a flowing inert gas, add 1 g of the polyborosilazane fluid prepared in step (1), 0.5 g of divinylbenzene cross-linking agent, and 1 g of ethanol tantalum modifier to a reaction flask. After magnetically stirring for 1 h at room temperature to mix evenly, then dropwise add a trace amount of Karstedt catalyst, and place it in an oil bath at 50 °C for reaction for 4 h to obtain an ethanol tantalum-modified polyborosilazane oligomer fluid; (3) Place the ethanol tantalum-modified polyborosilazane oligomer fluid in step (2) in a mold, put it into a tubular furnace, and cure it at a high temperature of 500 °C for 3 h under the protection of an inert gas to obtain an ablation-resistant resin.

[0035] Example 4 (1) Slowly add 23.4 g of boron trichloride, 23.0 g of methyldichlorosilane, and 129.1 g of hexamethyldisilazane dropwise into a three-necked flask placed in a -30 °C low-temperature bath, and continuously introduce an inert gas. First, slowly heat the reaction system to 150 °C and keep it warm for 3 h. After the reaction, remove the by-products by reduced pressure; then raise the temperature to 250 °C and keep it warm for 3 h. The reactants further undergo a polycondensation reaction at high temperature to obtain a turbid viscous polyborosilazane fluid; (2) Under the protection of a flowing inert gas, add 1 g of the polyborosilazane fluid prepared in step (1), 0.75 g of divinylbenzene cross-linking agent, and 0.75 g of ethanol tantalum modifier to a reaction flask. After magnetically stirring for 1 h at room temperature to mix evenly, then dropwise add a trace amount of Karstedt catalyst, and place it in an oil bath at 60 °C for reaction for 2 h to obtain an ethanol tantalum-modified polyborosilazane oligomer fluid; (3) Place the ethanol tantalum-modified polyborosilazane oligomer fluid in step (2) in a mold, put it into a tubular furnace, and cure it at a high temperature of 600 °C for 2 h under the protection of an inert gas to obtain an ablation-resistant resin.

[0036] Comparative Example 1 (1) Slowly add 23.4 g of boron trichloride, 23.0 g of methyldichlorosilane, and 129.1 g of hexamethyldisilazane dropwise into a three-necked flask placed in a -30 °C low-temperature bath, and continuously introduce an inert gas. First, slowly heat the reaction system to 130 °C and keep it warm for 5 h. After the reaction, remove the by-products under reduced pressure; then raise the temperature to 240 °C and keep it warm for 3 h. The reactants further undergo a polycondensation reaction at high temperature to obtain a turbid and viscous polyborosilazane fluid; (2) Place the polyborosilazane fluid in step (1) into a mold, put it into a tubular furnace, and cure it at a high temperature of 400 °C for 4 h under the protection of an inert gas to obtain a polyborosilazane resin.

[0037] Comparative Example 2 (1) Slowly add 23.4 g of boron trichloride, 23.0 g of methyldichlorosilane, and 129.1 g of hexamethyldisilazane dropwise into a three-necked flask placed in a -30 °C low-temperature bath, and continuously introduce an inert gas. First, slowly heat the reaction system to 130 °C and keep it warm for 5 h. After the reaction, remove the by-products under reduced pressure; then raise the temperature to 240 °C and keep it warm for 3 h. The reactants further undergo a polycondensation reaction at high temperature to obtain a turbid and viscous polyborosilazane fluid; (2) Under the protection of a flowing inert gas, add 1 g of the polyborosilazane fluid prepared in step (1) and 1 g of divinylbenzene cross-linking agent into a reaction flask. After magnetically stirring for 1 h at room temperature to mix evenly, a polyborosilazane oligomer fluid is obtained; (3) Place the polyborosilazane oligomer fluid in step (2) into a mold, put it into a tubular furnace, and cure it at a high temperature of 400 °C for 4 h under the protection of an inert gas to obtain a polyborosilazane resin.

[0038] Figure 1 It is a thermogravimetric test data graph of the resins prepared in Examples 1, 2, 3, 4 and Comparative Examples 1 and 2. Table 1 lists the specific values of the char yields of each resin at 800 °C.

[0039] Table 1 Char Yields of Each Resin at 800 °C

[0040] From Figure 1As can be seen from Table 1, compared with Comparative Example 1, the char yield of the crosslinked polyborosilazane resin in Comparative Example 2 at 800 °C has increased, indicating that the introduction of divinylbenzene into the resin oligomer can increase the crosslinking degree and high-temperature resistance of the product. However, simply introducing divinylbenzene, the improvement in the high-temperature resistance of the resin is relatively small. Compared with Comparative Example 2, after being modified with tantalum ethoxide in Examples 1 to 4 of the present invention, the high-temperature resistance of the resin has been greatly improved, and the char yields of the resins in Examples 1 to 4 all exceed 70%. The char yield of the tantalum ethoxide-modified polyborosilazane resin prepared in Example 1 with the best performance tested in the present invention at 800 °C has increased by 32% compared with the pure polyborosilazane resin in Comparative Example 1, and has increased by 25.6% compared with the polyborosilazane resin in Comparative Example 2, indicating that introducing tantalum elements into polyborosilazane can greatly improve its high-temperature resistance.

Claims

1. A method for preparing an ablation-resistant tantalum ethoxide modified polyborosilazane resin, characterized in that: include; S1, under the protection of an inert atmosphere, reacting boron trichloride, methyldichlorosilane and hexamethyldisilazane to obtain a polyborosilazane fluid; S2, under the protection of an inert atmosphere, reacting a polyborosilazane fluid, divinylbenzene and tantalum ethoxide in the presence of a catalyst to obtain a tantalum ethoxide-modified polyborosilazane oligomer fluid; S3, under the protection of an inert atmosphere, heating and curing the tantalum ethoxide modified polyborosilazane oligomer fluid to obtain an ablation-resistant resin.

2. The method for preparing the ablation-resistant tantalum ethoxide modified polyborosilazane resin according to claim 1, characterized in that: S1 specifically comprises: mixing boron trichloride, methyldichlorosilane and hexamethyldisilazane in a low temperature bath, and then heating to react.

3. The method for preparing the ablation-resistant tantalum ethoxide modified polyborosilazane resin according to claim 2, characterized in that: The temperature of the low temperature bath is -40~-10 ℃.

4. The method for preparing the ablation-resistant tantalum ethoxide modified polyborosilazane resin according to claim 2, characterized in that: The specific steps of heating the reaction are: first raising the temperature to 120°C~150°C, reacting for 3~6 hours, and then raising the temperature to 230~260°C, reacting for 2~4 hours.

5. The method for preparing the ablation-resistant tantalum ethoxide modified polyborosilazane resin according to claim 1, characterized in that: In S2, the mass ratio of polyborosilazane fluid, divinylbenzene and tantalum ethoxide is 1:(0.5~2):(0.25~1).

6. The method for preparing the ablation-resistant tantalum ethoxide modified polyborosilazane resin according to claim 1, characterized in that: In S2, the catalyst is a Karstedt catalyst.

7. The method for preparing the ablation-resistant tantalum ethoxide modified polyborosilazane resin according to claim 1, characterized in that: In S2, the reaction temperature is 40~60 °C and the reaction time is 2~6 h.

8. The method for preparing the ablation-resistant tantalum ethoxide modified polyborosilazane resin according to claim 1, characterized in that: In S3, the curing temperature is 300~600 °C and the curing time is 2~5 h.

9. An ablation-resistant tantalum ethoxide modified polyborosilazane resin obtained by the preparation method according to any one of claims 1 to 8.

10. Use of the ablation-resistant tantalum ethoxide modified polyborosilazane resin according to claim 9 as a thermal protection material.

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