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Low-oxygen liquid SiHfBCN ceramic precursor, preparation method and SiHfBCN ceramic

A ceramic precursor and precursor technology, applied in the field of inorganic materials, can solve the problems of poor rheological properties, decreased performance of composite materials, low ceramic yield, etc., achieve excellent high temperature resistance and oxidation resistance, improve processing performance, flow Variable performance controllable effects

Inactive Publication Date: 2020-07-10
AEROSPACE RES INST OF MATERIAL & PROCESSING TECH +1
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  • Application Information

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Problems solved by technology

[0004] However, the sol-gel method is usually used to prepare precursors containing refractory metal hafnium, but the hafnium precursors prepared by this method have low solubility, poor stability, and low ceramic yield, which is not suitable for the preparation of large-scale ceramic matrix thermal structural composites. In addition, a large amount of oxygen is easily introduced during the preparation process to cause damage to the carbon fiber, resulting in a decrease in the performance of the composite material.
The polymer precursor method is an effective method to prepare oxygen-free precursors containing refractory metal hafnium, but there are also problems such as excessive rigidity of the main chain of the precursor, low solubility, and poor rheological properties.

Method used

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  • Low-oxygen liquid SiHfBCN ceramic precursor, preparation method and SiHfBCN ceramic
  • Low-oxygen liquid SiHfBCN ceramic precursor, preparation method and SiHfBCN ceramic
  • Low-oxygen liquid SiHfBCN ceramic precursor, preparation method and SiHfBCN ceramic

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preparation example Construction

[0041]The preparation method of the above-mentioned low-oxygen liquid SiHfBCN ceramic precursor specifically includes the following steps:

[0042] Step 1: replacing the air in the Schlenk reactor with an inert gas, specifically, firstly evacuating the reactor and then filling the inert gas, repeating 3 to 5 times. Add a certain amount of organic solvent, put the unsaturated group-containing liquid SiBCN precursor and the unsaturated group-containing hafnium precursor into the reactor in a certain proportion at 20 ~ 30 ℃, and add a certain amount of free radical initiator , a homogeneous solution is obtained after fully stirring.

[0043] Step 2: heating the obtained homogeneous solution to initiate radical polymerization between unsaturated groups in the system to obtain SiHfBCN precursor, the reaction temperature is 60-180°C, and the reaction time is 0.5-2h.

[0044] Step 3: After the reaction is completed, the temperature of the system is lowered to below 30 °C, and then t...

Embodiment 1

[0054] 1) The air in the Schlenk reactor is replaced with an inert gas, specifically, the reactor is first evacuated and then filled with an inert gas, repeating 3 to 5 times. Add solvent N,N-dimethylformamide 40ml, at 25 ℃ add SiBCN precursor (PSNB) 10g, dicocyl diallyl hafnium 10g, dicumyl peroxide 0.1g, stir well and get brown color Homogeneous solution.

[0055] 2) The homogeneous solution obtained above was heated to 140°C and kept for 0.5h.

[0056] 3) After the reaction is completed, the system temperature is lowered to below 30°C, and then the vacuum pump is turned on, and the solvent is removed by distillation under reduced pressure. The distillation temperature is 60°C, and the vacuum degree is -0.09 to -0.1Mpa, until no solvent escapes in the system. The vacuum was stopped, and the temperature was lowered, and finally a brown liquid SiHfBCN precursor was obtained.

[0057] 4) The SiHfBCN precursor is placed in a tube furnace, and the SiHfBCN ceramic can be obtaine...

Embodiment 2

[0061] 1) The air in the Schlenk reactor is replaced with an inert gas, specifically, the reactor is first evacuated and then filled with an inert gas, repeating 3 to 5 times. Add solvent N,N-dimethylformamide 30ml, add SiBCN precursor (PSNB) 10g, dimethyldiallyl hafnium 5g, dicumyl peroxide 0.075g at 25°C, stir well and get brown color Homogeneous solution.

[0062] 2) The homogeneous solution obtained above was heated to 140°C and kept for 0.5h.

[0063] 3) After the reaction is completed, the system temperature is lowered to below 30°C, and then the vacuum pump is turned on, and the solvent is removed by distillation under reduced pressure. The distillation temperature is 60°C, and the vacuum degree is -0.09 to -0.1Mpa, until no solvent escapes in the system. The vacuum was stopped, and the temperature was lowered, and finally a brown liquid SiHfBCN precursor was obtained.

[0064] 4) The SiHfBCN precursor is placed in a tube furnace, and the SiHfBCN ceramic can be obtain...

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Abstract

The invention relates to a novel low-oxygen liquid SiHfBCN ceramic precursor and a preparation method thereof. A SiBCN precursor and a hafnium precursor are dissolved in an organic solvent to form a homogeneous solution, a free radical initiator is added, heating is performed to initiate a free radical polymerization reaction of double bonds between the two precursors, and heating or vacuumizing is performed to remove the solvent to obtain viscous liquid, namely a SiHfBCN ceramic precursor. After the SiHfBCN ceramic precursor is subjected to pyrolysis treatment, homogeneous SiHfBCN ceramic canbe obtained. According to the method, the problem of poor solubility of the hafnium precursor is solved, meanwhile, a silicon-hafnium-boron-carbon-nitrogen precursor is prepared through free radicalpolymerization of unsaturated bonds, introduction of an oxygen element is avoided, no byproduct is generated, the preparation process is simple, and the problem that a traditional refractory metal hafnium compound is high in preparation temperature and difficult to sinter is solved.

Description

technical field [0001] The invention relates to a low-oxygen liquid SiHfBCN ceramic precursor, a preparation method and SiHfBCN ceramics, and belongs to the field of inorganic materials. Background technique [0002] SiC and SiBCN ceramics have excellent high temperature resistance and oxidation resistance, and are currently commonly used carbon fiber reinforced ceramic matrix thermal structural composites. usage requirements. The melting point of the refractory metal hafnium compound is above 3000 ℃, and the melting point of its oxide is also above 2500 ℃, which has excellent high temperature resistance. Difference. The introduction of refractory metal hafnium compounds into SiBCN ceramics to form homogeneous SiHfBCN ceramics can effectively combine the excellent oxidation resistance of Si-based ceramics and the excellent high temperature stability and ablation resistance of hafnium compounds, and can be used above 2000 ℃, It is the research focus in the field of ultra-h...

Claims

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Application Information

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IPC IPC(8): C08F283/00C08F230/04C04B35/58
CPCC08F283/00C04B35/58
Inventor 冯志海许艺芬胡继东俸翔田跃龙李媛
Owner AEROSPACE RES INST OF MATERIAL & PROCESSING TECH
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