A SiBCN ceramic precursor with low viscosity and high ceramic yield, and preparation method and use thereof

Abstract

The present invention provides a low-viscosity, high-ceramic yield SiBCN ceramic precursor and its preparation method and use. The SiBCN ceramic precursor contains silicon, boron, carbon and nitrogen elements; the SiBCN ceramic precursor does not contain organic solvents and has a viscosity of ≤20mPa·s; the SiBCN ceramic precursor proposed by the present invention can maintain the excellent properties of SiBCN ceramic products such as high thermal stability and high oxidation resistance, while focusing on improving the process performance of the SiBCN ceramic precursor, so as to achieve the infiltration and sealing of micro-nano porous materials. The extremely low-viscosity, addition-curable SiBCN ceramic precursor provided by the present invention can achieve impregnation and infiltration of micro-nano pores on the surface of composite materials that cannot be filled by conventional precursors, and can induce vinyl addition curing by heating, so that the impregnation and infiltration precursor is retained in situ in the pores. The above characteristics can greatly improve the impregnation and sealing effects.

Description

Technical Field

[0001] The invention belongs to the field of ceramic materials, and in particular relates to a SiBCN ceramic precursor with low viscosity and high ceramic yield, and a preparation method and application thereof. Background Art

[0002] Silicon boron carbon nitride (SiBCN) ceramics have excellent high temperature resistance (above 2000℃), oxidation resistance and high temperature creep resistance, and are an important high-performance multi-element ceramic material. SiBCN ceramics are generally prepared by curing and pyrolysis of SiBCN ceramic precursors containing elements such as silicon, boron, carbon and nitrogen in the molecule.

[0003] At present, most SiBCN ceramic precursors are solids with high molecular weight or high viscosity liquids, which means that when they are used as the matrix of ceramic-based composite materials, solvents often need to be added for dilution to reduce the viscosity. This operation will result in a low overall ceramic yield from precursor to ceramic and a long preparation cycle for the composite material. In addition, the impregnation and cracking process of ceramic-based composite materials is currently the mainstream preparation process for large-sized special-shaped components, and precursors such as polycarbosilane and polyzirconia are usually used as raw materials. The viscosity of these precursors is usually above 100mPa·s, and the density of the ceramic-based composite materials prepared therefrom can only reach about 90%. The remaining pores are limited by the viscosity of the precursor and cannot be impregnated and infiltrated, and the density cannot be further increased. Summary of the invention

[0004] In order to improve the technical problems existing in the above-mentioned prior art, the present invention provides a SiBCN ceramic precursor with low viscosity and high ceramic yield, and a preparation method and use thereof. The SiBCN ceramic precursor has the characteristics of low viscosity and high ceramic yield, and the ceramic-based composite material prepared from the SiBCN ceramic precursor has good compactness and high density, which meets the performance requirements of ceramic-based composite components for air tightness or ablation resistance. At the same time, the preparation process of the SiBCN ceramic precursor is simple, further expanding its application in the fields of ceramic-based composite materials and ceramic coatings.

[0005] In order to achieve the above-mentioned invention object, the present invention adopts the following technical scheme:

[0006] A SiBCN ceramic precursor, wherein the SiBCN ceramic precursor contains silicon, boron, carbon and nitrogen elements; the SiBCN ceramic precursor satisfies the following three conditions at the same time:

[0007] (1) The SiBCN ceramic precursor has a curing weight loss rate of ≤10% at 200-250° C. and in an inert atmosphere;

[0008] (2) After the SiBCN ceramic precursor is pyrolyzed at 900° C. in an inert atmosphere, the oxygen content in the ceramic is ≤ 2%;

[0009] (3) The weight loss rate of the SiBCN ceramic precursor between 900° C. and 1500° C. in an inert atmosphere is ≤5%.

[0010] According to an embodiment of the present invention, the SiBCN ceramic precursor satisfies (1) the curing weight loss rate of the SiBCN ceramic precursor at 200-250°C and inert atmosphere is ≤10%, indicating that the SiBCN ceramic precursor has the characteristic of low curing residual weight; wherein, the curing weight loss rate refers to the proportion of weight lost by the precursor before and after curing, specifically the weight difference between the precursor before and after curing and the weight ratio of the precursor before curing, that is, (weight of the precursor-weight of the cured product) / weight of the precursor; wherein 200-250°C means that the curing temperature is any temperature between 200 and 250°C, that is, the curing weight loss rate of the SiBCN ceramic precursor when cured from room temperature to any temperature between 200 and 250°C is ≤10%.

[0011] According to an embodiment of the present invention, the SiBCN ceramic precursor satisfies (2) the oxygen content in the ceramic after the SiBCN ceramic precursor is cracked at 900° C. in an inert atmosphere is ≤2%, indicating that the SiBCN ceramic precursor has the characteristic of low oxygen content.

[0012] According to an embodiment of the present invention, the SiBCN ceramic precursor satisfies (3) the weight loss rate of the SiBCN ceramic precursor between 900°C and 1500°C under an inert atmosphere is ≤5%; indicating that the SiBCN ceramic product prepared by the SiBCN ceramic precursor has the characteristic of high thermal stability; wherein the weight loss rate refers to the weight ratio of the ceramic obtained by pyrolysis of the precursor at 900°C after being heated to pyrolysis at 1500°C, that is, (ceramic weight before pyrolysis at 1500°C - ceramic weight after pyrolysis at 1500°C) / ceramic weight before pyrolysis at 1500°C.

[0013] According to an embodiment of the present invention, the SiBCN ceramic precursor further contains a free radical initiator.

[0014] According to an embodiment of the present invention, the free radical initiator is selected from at least one of azobisisobutyronitrile, dicumyl peroxide, dibenzoyl peroxide and azobisisoheptylnitrile.

[0015] According to an embodiment of the present invention, the weight of the free radical initiator accounts for 0.5% to 3% of the total weight of the SiBCN ceramic precursor, such as 0.5%, 1%, 1.5%, 2%, 2.5% or 3%. The introduction of the free radical initiator can reduce the curing temperature of the SiBCN ceramic precursor and reduce its curing weight loss rate.

[0016] According to an embodiment of the present invention, the SiBCN ceramic precursor does not contain an organic solvent and has a viscosity of ≤20 mPa·s, for example, 1 to 18 mPa·s, such as 1 mPa·s, 2 mPa·s, 3 mPa·s, 4 mPa·s, 5 mPa·s, 6 mPa·s, 8 mPa·s, 10 mPa·s, 12 mPa·s, 15 mPa·s, 18 mPa·s or 20 mPa·s, indicating that the SiBCN ceramic precursor has a lower viscosity.

[0017] According to an embodiment of the present invention, the viscosity of the SiBCN ceramic precursor after being sealed and stored at 25° C. for 12 months is ≤25 mPa·s, indicating that the SiBCN ceramic precursor has good storage stability.

[0018] According to an embodiment of the present invention, the SiBCN ceramic precursor is in a liquid state at room temperature.

[0019] According to an embodiment of the present invention, the SiBCN ceramic precursor can form an amorphous SiBCN ceramic after being cracked at 900-1500° C. in an inert atmosphere.

[0020] According to an embodiment of the present invention, the yield of the SiBCN ceramic produced by cracking the SiBCN ceramic precursor at 1500° C. in an inert atmosphere is ≥55%, such as ≥60%, that is, the weight of the SiBCN ceramic / the weight of the SiBCN ceramic precursor is ≥55%, such as ≥60%. This indicates that the SiBCN ceramic precursor has a high ceramic yield.

[0021] The present invention also provides a SiBCN ceramic precursor, which is prepared by a one-pot reaction using boron trichloride as a boron source, vinyl dichlorosilane as a silicon source, ammonia as a nitrogen source, and trimethylchlorosilane as a capping agent.

[0022] According to an embodiment of the present invention, the SiBCN ceramic precursor is defined as described above.

[0023] According to an embodiment of the present invention, the vinyl-containing dichlorosilane is at least one selected from methylvinyldichlorosilane, vinyldichlorosilane and divinyldichlorosilane.

[0024] According to an embodiment of the present invention, methyl hydrogen dichlorosilane and / or dimethyl dichlorosilane may be selectively added to the silicon source, wherein the total mole number of methyl hydrogen dichlorosilane and / or dimethyl dichlorosilane does not exceed the total mole number of vinyl dichlorosilane. Exemplarily, the silicon source is vinyl dichlorosilane, or a combination of vinyl dichlorosilane and methyl hydrogen dichlorosilane, or a combination of vinyl dichlorosilane and dimethyl dichlorosilane, or a combination of vinyl dichlorosilane, methyl hydrogen dichlorosilane and dimethyl dichlorosilane.

[0025] According to an embodiment of the present invention, the one-pot reaction refers to mixing a boron source, a silicon source, a nitrogen source and a capping agent, reacting them, and directly obtaining the SiBCN ceramic precursor of the present application without separation of intermediates.

[0026] According to an embodiment of the present invention, a boron source, a silicon source, a nitrogen source and a capping agent are mixed at a temperature of -5 to -20°C; illustratively, the boron source, the silicon source and the capping agent are mixed at a temperature of -5 to -10°C; then, a nitrogen source is added at a temperature of -15 to -20°C and mixing is continued.

[0027] According to an embodiment of the present invention, the reaction is, for example, first reacted at 25-35°C for 3-6 hours, then distilled under reduced pressure at 25-40°C for 1-5 hours, and finally distilled under reduced pressure at 100-120°C for 1-2 hours.

[0028] According to an embodiment of the present invention, the molar ratio of the boron source to the capping agent is 1:(0.15-0.35), for example, 1:0.15, 1:0.20, 1:0.25, 1:0.30 or 1:0.35.

[0029] According to an embodiment of the present invention, the molar ratio of the boron source to the silicon source is 1:(1-3), for example, 1:1, 1:1.5, 1:2, 1:2.5 or 1:3.

[0030] According to an embodiment of the present invention, the molar amount of the nitrogen source is 1.3 to 2 times the sum of the molar number of chlorine in the boron source, the molar number of chlorine in the silicon source and the molar number of chlorine in the capping agent, for example, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9 or 2 times.

[0031] According to an embodiment of the present invention, the one-pot reaction is carried out in the presence of a solvent.

[0032] According to an embodiment of the present invention, the solvent is selected from at least one of petroleum ether, n-heptane, n-hexane, toluene and xylene.

[0033] According to an embodiment of the present invention, the amount of the solvent is 4 to 10 times, for example, 4, 5, 6, 7, 8, 9 or 10 times the total weight of the boron source, the silicon source and the capping agent.

[0034] According to an embodiment of the present invention, the one-pot reaction is carried out under the protection of an inert atmosphere.

[0035] According to an embodiment of the present invention, the inert atmosphere is at least one of nitrogen, argon or helium.

[0036] According to an embodiment of the present invention, the one-pot reaction further comprises adding a free radical initiator after completion.

[0037] The present invention also provides a method for preparing the above-mentioned SiBCN ceramic precursor, which comprises the following steps: using boron trichloride as a boron source, vinyl dichlorosilane as a silicon source, ammonia as a nitrogen source, and trimethylchlorosilane as a capping agent to prepare the SiBCN ceramic precursor through a one-pot reaction.

[0038] According to an embodiment of the present invention, the preparation method comprises the following steps: mixing boron trichloride, vinyl dichlorosilane, optionally adding or not adding methyl hydrogen dichlorosilane and / or dimethyl dichlorosilane, ammonia and trimethyl chlorosilane, reacting to prepare the SiBCN ceramic precursor.

[0039] According to an embodiment of the present invention, the mixing is carried out at a temperature of -20 to -5°C, that is, the boron source, silicon source, nitrogen source and capping agent are mixed at a temperature of -5 to -20°C; illustratively, the boron source, silicon source and capping agent are mixed at a temperature of -5 to -10°C; then, the nitrogen source is added at a temperature of -15 to -20°C and the mixing is continued.

[0040] According to an embodiment of the present invention, the reaction is, for example, first reacted at 25-35°C for 3-6 hours, then distilled under reduced pressure at 25-40°C for 1-5 hours, and finally distilled under reduced pressure at 100-120°C for 1-2 hours.

[0041] According to an embodiment of the present invention, the preparation method comprises the following steps:

[0042] (1) Under the protection of an inert atmosphere, adding a solvent to the system;

[0043] (2) at a temperature of -5 to -10°C, introducing boron trichloride gas into the system, followed by adding vinyl dichlorosilane, optionally with or without methyl hydrogen dichlorosilane and / or dimethyl dichlorosilane, and trimethyl chlorosilane;

[0044] (3) introducing ammonia gas into the system at a temperature of -15 to -20°C;

[0045] (4) reacting at 25-35°C for 3-6 hours and filtering;

[0046] (5) distilling the filtrate under reduced pressure at 25-40°C for 1-5 hours, heating it to 100-120°C and distilling it under reduced pressure for 1-2 hours;

[0047] (6) Add a free radical initiator to the system and stir evenly to obtain the SiBCN ceramic precursor.

[0048] The present invention also provides application of the SiBCN ceramic precursor in ceramic-based composite materials and ceramic coatings.

[0049] According to an embodiment of the present invention, the SiBCN ceramic precursor is used for preparing a ceramic-based composite material by a PIP method and as a sealing coating of a ceramic-based composite material.

[0050] Beneficial effects:

[0051] The present invention provides a low-viscosity, high-ceramic yield SiBCN ceramic precursor, and a preparation method and use thereof. The SiBCN ceramic precursor proposed in the present invention can maintain the excellent properties of the SiBCN ceramic product such as high thermal stability and high oxidation resistance, while focusing on improving the process performance of the SiBCN ceramic precursor, so as to achieve the infiltration and sealing of micro-nano porous materials. The extremely low-viscosity, addition-curable SiBCN ceramic precursor provided by the present invention can achieve the impregnation and infiltration of micro-nano pores on the surface of composite materials that cannot be filled by conventional precursors, and can induce vinyl addition curing by heating, so that the impregnated and infiltrated precursor is retained in situ in the pores. The above characteristics can greatly improve the impregnation and sealing effects. The use of the SiBCN ceramic precursor of the present invention can further increase the density of the composite material, and can further improve the density, meeting the performance requirements of ceramic-based composite components for air tightness or ablation resistance. DETAILED DESCRIPTION

[0052] The present invention will be described in further detail below in conjunction with specific embodiments. It should be understood that the following embodiments are only exemplary descriptions and explanations of the present invention and should not be construed as limiting the scope of protection of the present invention. All technologies implemented based on the above content of the present invention are included in the scope that the present invention is intended to protect.

[0053] Unless otherwise specified, the experimental methods used in the following examples are all conventional methods; the reagents, materials, etc. used in the following examples, unless otherwise specified, can be obtained from commercial channels.

[0054] Example 1

[0055] In this embodiment, the SiBCN ceramic precursor is prepared by the following method.

[0056] Under the protection of inert gas, add 2kg of n-heptane to the system; cool down to -5℃, introduce 1mol of boron trichloride gas into the system, then add 1.5mol of methylvinyldichlorosilane, 0.5mol of methylhydrogendichlorosilane and 0.15mol of trimethylchlorosilane; continue to cool down to -15℃, introduce 9.3mol of ammonia into the system. Return the system to 25℃ for reaction for 3h, filter; distill the filtrate under reduced pressure at 25℃ for 1h, heat to 100℃ for distillation under reduced pressure for 2h; add 0.5% of azobisisobutyronitrile to the system, stir evenly, and obtain 160.5g of SiBCN ceramic precursor (yield 84.3%), the obtained precursor does not contain organic solvent and has a viscosity of 5mPa·s.

[0057] The obtained precursor was heated to 60°C at 3°C / min under nitrogen and kept for 1h, then heated to 150°C at 3°C / min and kept for 1h, then heated to 200°C at 3°C / min and kept for 1h, then heated to 250°C at 3°C / min and kept for 2h to obtain a solidified product with a curing weight loss rate of 5.2%. The obtained solidified product was pyrolyzed at 900°C in a nitrogen atmosphere with a yield of 70.23%, and the oxygen content in the ceramic product was 1.68%. The 900°C pyrolysis product was pyrolyzed at 1500°C at 10°C / min in an argon atmosphere for 2h with a weight loss rate of 4%.

[0058] Example 2

[0059] In this embodiment, the SiBCN ceramic precursor is prepared by the following method.

[0060] Under the protection of inert gas, add 2.2kg of n-hexane to the system; cool to -10℃, introduce 1mol of boron trichloride gas into the system, then add 1.5mol of methylvinyldichlorosilane and 0.3mol of trimethylchlorosilane; continue to cool to -20℃, introduce 9.5mol of ammonia into the system. Return the system to 35℃ for reaction for 3h, filter; distill the filtrate under reduced pressure at 40℃ for 5h, heat to 100℃ for distillation under reduced pressure for 1h; add 1% of diisopropylbenzene peroxide to the system, stir evenly, and obtain 150.2g of SiBCN ceramic precursor (yield 93.4%), which contains no organic solvent and has a viscosity of 3mPa·s.

[0061] The obtained precursor was heated to 100°C at 3°C / min under nitrogen and kept for 1h, then heated to 150°C at 3°C / min and kept for 1h, then heated to 200°C at 3°C / min and kept for 1h, then heated to 250°C at 3°C / min and kept for 2h to obtain a solidified product with a curing weight loss rate of 9.5%. The obtained solidified product was pyrolyzed at 900°C in a nitrogen atmosphere with a yield of 67.92%, and the oxygen content in the ceramic product was 1.23%. The 900°C pyrolysis product was pyrolyzed at 1500°C at 10°C / min in an argon atmosphere for 2h with a weight loss rate of 4.5%.

[0062] Example 3

[0063] In this embodiment, the SiBCN ceramic precursor is prepared by the following method.

[0064] Under the protection of inert gas, 4.5 kg of toluene was added to the system; the temperature was lowered to -10 ° C, 1 mol of boron trichloride gas was introduced into the system, and then 1.5 mol of vinyl dichlorosilane, 1.5 mol of dimethyl dichlorosilane and 0.35 mol of trimethyl chlorosilane were added; the temperature was further lowered to -20 ° C, and 18 mol of ammonia gas was introduced into the system. The system was warmed up to 30 ° C for reaction for 3 hours, and filtered; the filtrate was distilled at 40 ° C for 3 hours, and then heated to 100 ° C for distillation at reduced pressure for 2 hours; 3% of diisopropylbenzene peroxide was added to the system, and stirred evenly to obtain 230.7 g of SiBCN ceramic precursor (yield 85.3%), which contained no organic solvent and had a viscosity of 15 mPa·s.

[0065] The obtained precursor was heated to 100°C at 3°C / min under nitrogen and kept for 1h, then heated to 150°C at 3°C / min and kept for 1h, then heated to 200°C at 3°C / min and kept for 1h, then heated to 250°C at 3°C / min and kept for 2h to obtain a solidified product with a curing weight loss rate of 8.3%. The obtained solidified product was pyrolyzed at 900°C in a nitrogen atmosphere with a yield of 66.85%, and the oxygen content in the ceramic product was 1.1%. The 900°C pyrolysis product was pyrolyzed at 1500°C at 10°C / min in an argon atmosphere for 2h with a weight loss rate of 3.8%.

[0066] Example 4

[0067] The other operations are the same as those in Example 1, except that the system is returned to 25°C for reaction for 3 hours and filtered; the filtrate is distilled at 25°C under reduced pressure for 1 hour, heated to 100°C for distillation under reduced pressure for 2 hours, and then continued to be heated to 170°C for distillation under reduced pressure for 1 hour; 0.5% of azobisisobutyronitrile is added to the system and stirred evenly to obtain 110.89 g (yield 58.27%) of SiBCN ceramic precursor, and the viscosity of the obtained precursor is 400 mPa·s.

[0068] The obtained precursor was heated to 60°C at 3°C / min under nitrogen and kept for 1h, then heated to 150°C at 3°C / min and kept for 1h, then heated to 200°C at 3°C / min and kept for 1h, then heated to 250°C at 3°C / min and kept for 2h to obtain a solidified product with a curing weight loss rate of 2.3%. The obtained solidified product was pyrolyzed at 900°C in a nitrogen atmosphere with a yield of 75.4%, and the oxygen content in the ceramic product was 1.7%. The 900°C pyrolysis product was pyrolyzed at 1500°C at 10°C / min in an argon atmosphere for 2h with a weight loss rate of 3.5%.

[0069] Comparative Example 1

[0070] The other operations were the same as those in Example 1, except that trimethylchlorosilane capping agent was not added.

[0071] 40.1 g (yield 22.2%) of SiBCN ceramic precursor was obtained, and the viscosity of the precursor was 150 mPa·s. The obtained precursor was heated to 60°C at 3°C / min under nitrogen and kept for 1 hour, then heated to 150°C at 3°C / min and kept for 1 hour, then heated to 200°C at 3°C / min and kept for 1 hour, then heated to 250°C at 3°C / min and kept for 2 hours to obtain a solidified product, and the solidification weight loss rate was 3.7%. The obtained solidified product had a pyrolysis yield of 76.3% at 900°C in a nitrogen atmosphere, and the oxygen content in the ceramic product was 2.2%. The 900°C pyrolysis product was heated to 1500°C at 10°C / min in an argon atmosphere and pyrolyzed for 2 hours, and the weight loss rate was 12%.

[0072] Comparative Example 2

[0073] The other operations were the same as in Example 1, except that dimethyldichlorosilane was used to replace methylvinyldichlorosilane.

[0074] 165.7 g (yield 87.07%) of SiBCN ceramic precursor was obtained, and the viscosity of the precursor was 10 mPa·s. The obtained precursor was heated to 60°C at 3°C / min under nitrogen and kept warm for 1 hour, then heated to 150°C at 3°C / min and kept warm for 1 hour, then heated to 200°C at 3°C / min and kept warm for 1 hour, then heated to 250°C at 3°C / min and kept warm for 2 hours to obtain a solidified product, and the solidification weight loss rate was 30.7%. The obtained solidified product had a pyrolysis yield of 62.8% at 900°C in a nitrogen atmosphere, and the oxygen content in the ceramic product was 1.33%. The 900°C pyrolysis product was heated to 1500°C at 10°C / min in an argon atmosphere for 2 hours, and the weight loss rate was 8%.

[0075] The above is an explanation of the embodiments of the present invention. However, the present invention is not limited to the above embodiments. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A SiBCN ceramic precursor, It is characterized in that The SiBCN ceramic precursor contains silicon, boron, carbon and nitrogen elements; the SiBCN ceramic precursor also satisfies: (1) The SiBCN ceramic precursor has a curing weight loss rate of ≤10% at 200-250°C in an inert atmosphere; (2) After the SiBCN ceramic precursor is pyrolyzed at 900° C. in an inert atmosphere, the oxygen content in the ceramic is ≤ 2%; (3) The SiBCN ceramic precursor has a weight loss rate of ≤5% between 900°C and 1500°C in an inert atmosphere; The SiBCN ceramic precursor contains a free radical initiator; the free radical initiator is selected from at least one of azobisisobutyronitrile, diisopropylbenzene peroxide, dibenzoyl peroxide and azobisisoheptylnitrile; The SiBCN ceramic precursor does not contain an organic solvent and has a viscosity of ≤15 mPa·s; and / or, the SiBCN ceramic precursor is cured, pyrolyzed at 900° C. in an inert atmosphere, and pyrolyzed at 1500° C. in an inert atmosphere, to obtain a yield of SiBCN ceramics of ≥55%; The SiBCN ceramic precursor is prepared by a one-pot reaction using boron trichloride as a boron source, vinyl-containing dichlorosilane as a silicon source, ammonia as a nitrogen source, and trimethylchlorosilane as a capping agent.

2. The SiBCN ceramic precursor according to claim 1, It is characterized in that The weight of the free radical initiator accounts for 0.5% to 3% of the total weight of the SiBCN ceramic precursor.

3. The SiBCN ceramic precursor according to claim 1, It is characterized in that The vinyl-containing dichlorosilane is selected from at least one of methylvinyldichlorosilane, vinyldichlorosilane and divinyldichlorosilane; The silicon source includes methyl hydrogen dichlorosilane and / or dimethyl dichlorosilane, and the total mole number of methyl hydrogen dichlorosilane and / or dimethyl dichlorosilane does not exceed the total mole number of vinyl-containing dichlorosilane.

4. The SiBCN ceramic precursor according to claim 1, It is characterized in that Mix the boron source, silicon source, nitrogen source and capping agent at a temperature of -5 to -20°C; The reaction is firstly carried out at 25-35° C. for 3-6 hours, then distilled under reduced pressure at 25-40° C. for 1-5 hours, and finally distilled under reduced pressure at 100-120° C. for 1-2 hours.

5. The SiBCN ceramic precursor according to claim 1, It is characterized in that The molar ratio of the boron source to the end-capping agent is 1:(0.15-0.35); The molar ratio of the boron source to the silicon source is 1:(1-3); The molar amount of the nitrogen source is 1.3 to 2 times the sum of the molar number of the chlorine element in the boron source, the molar number of the chlorine element in the silicon source and the molar number of the chlorine element in the capping agent; The one-pot reaction includes adding a free radical initiator after completion.

6. A method for preparing the SiBCN ceramic precursor according to any one of claims 1 to 5, It is characterized in that The preparation method comprises the following steps: using boron trichloride as a boron source, using vinyl-containing dichlorosilane as a silicon source, using ammonia as a nitrogen source, and using trimethylchlorosilane as a capping agent to prepare the product through a one-pot reaction; The preparation method comprises the following steps: mixing boron trichloride, vinyl-containing dichlorosilane, methylhydrogendichlorosilane and / or dimethyldichlorosilane with or without addition, ammonia and trimethylchlorosilane, and reacting to prepare the SiBCN ceramic precursor.

7. The method for preparing a SiBCN ceramic precursor according to claim 6, It is characterized in that The mixing is carried out at a temperature of -20 to -5°C; The reaction is firstly carried out at 25-35° C. for 3-6 hours, then distilled under reduced pressure at 25-40° C. for 1-5 hours, and finally distilled under reduced pressure at 100-120° C. for 1-2 hours.

8. Use of the SiBCN ceramic precursor according to any one of claims 1 to 5 in ceramic matrix composites and ceramic coatings.