A method for synthesizing a tantalum carbide precursor containing unsaturated bonds and its application

Abstract

The present invention discloses a synthesis method and application of a tantalum carbide precursor containing an unsaturated bond. The synthesis method uses unsaturated alcohol instead of saturated alcohol to synthesize tantalum alkoxide (i.e., an unsaturated alcohol solution in which tantalum salt is dissolved), uses tantalum alkoxide as a tantalum source, and uses allyl phenolic resin as a carbon source. The TaC precursor is synthesized by free radical copolymerization. More C=C bond crosslinking sites are introduced into the precursor, so that the tantalum source and the carbon source are mixed intramolecularly through the C=C bond addition polymerization reaction, thereby improving the crosslinking degree of the precursor. The technical problem of few crosslinking sites and failure to achieve intramolecular mixing of the tantalum source and the carbon source in the prior art is solved.

Description

Technical Field

[0001] The invention relates to the technical field of ceramic materials, and in particular to a synthesis method and application of a tantalum carbide precursor containing an unsaturated bond. Background Art

[0002] Tantalum carbide (TaC) is a transition metal carbide ceramic. Due to its advantages such as high melting point (3880℃), high hardness (14-19 GPa), high elastic modulus (470-540 GPa), high tensile strength (600-700 MPa) and good high temperature performance, it has good application prospects in the field of ultra-high temperature resistant materials.

[0003] TaC is difficult to process and shape due to its high melting point, high hardness and difficulty in sintering. The traditional solid phase reaction method has high reaction temperature, low product purity and is only suitable for the preparation of TaC ceramic powder. The precursor conversion method can design the molecular structure of the precursor and then control the performance of the product. At the same time, it has good processability during the preparation process and can be used to prepare ceramic powders, fibers, coatings and composite material matrices. And because the raw material components can be evenly mixed at the molecular level, the diffusion distance between elements is shortened, thereby reducing the pyrolysis temperature and avoiding the problem of coarse grains, which has a high application value.

[0004] At present, TaC precursors are usually synthesized using tantalum alkoxide complexes. In the process of synthesizing tantalum alkoxide complex precursors, TaCl5 is mainly used as a metal source, and tantalum alkoxide is obtained by substitution reaction with alcohol. Since tantalum alkoxide hydrolyzes violently, ligands such as acetylacetone are used to react with tantalum alkoxide to form a complex to achieve controllable hydrolysis and condensation to obtain a polymer precursor. At the same time, in order to ensure that the subsequent carbon thermal reduction reaction is sufficient, a carbon source is often added to the precursor solution. This hydrolysis and condensation synthesis process has the disadvantages of few cross-linking sites and failure to achieve intramolecular mixing of tantalum source and carbon source. Summary of the invention

[0005] The technical problem to be solved by the present invention is to overcome the deficiencies of the prior art and provide a method for synthesizing a tantalum carbide precursor containing unsaturated bonds with a high degree of crosslinking and an application thereof.

[0006] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0007] A method for synthesizing a tantalum carbide precursor containing an unsaturated bond comprises the following steps:

[0008] Tantalum alkoxide is used as a tantalum source, and allyl-modified phenolic resin is used as a carbon source. The tantalum source and the carbon source are mixed and stirred, a free radical initiator is added, and a free radical copolymerization reaction is carried out at a temperature of 70 to 80° C. for 1 to 13 hours to obtain a tantalum carbide precursor containing an unsaturated bond. The tantalum alkoxide is obtained by a substitution reaction between a tantalum salt and an unsaturated alcohol containing an unsaturated bond in the molecule. The mass ratio of the carbon source to the tantalum source satisfies the carbon source: tantalum salt in the tantalum source = 0.4 to 0.8:1, and the unsaturated alcohol is one or more of 4-pentene-1-ol, 4-pentene-2-ol, 3-butene-1-ol and 1-pentene-3-ol.

[0009] As a further improvement to the above technical solution:

[0010] The free radical initiator is one or more of dicumyl peroxide, azobisisobutyronitrile, azobisisoheptylnitrile and didodecanol peroxide. In certain embodiments of the present invention, the free radical initiator may also be dicumyl peroxide, azobisisobutyronitrile or azobisisoheptyl, but dicumyl peroxide has a low decomposition temperature and is prone to decomposition under natural storage conditions to generate dimethylbenzyl alcohol, acetophenone and methane. Azo initiators are also self-reactive, decompose to release a large amount of heat and cyanide, and are toxic, flammable and explosive.

[0011] Preferably, the didodecanol peroxide used as the free radical initiator of the present invention is insensitive to vibration, and its decomposition products are low-toxic lauric acid ester and carbon dioxide, which is safer and easier to store.

[0012] Preferably, the amount of didodecanoyl peroxide used is 5 to 7 wt % of the total mass of the carbon source and the tantalum source.

[0013] The tantalum alkoxide is prepared by the following steps: mixing tantalum salt and unsaturated alcohol in a molar ratio of 1:6 to 10, and stirring for 0.5 to 1 h;

[0014] The tantalum salt is tantalum pentachloride. In certain embodiments of the present invention, the unsaturated alcohol uses 4-pentene-1-ol and 4-pentene-2-ol, but the cost is higher than that of 3-butene-1-ol and 1-pentene-3-ol. Preferably, the unsaturated alcohol is one or both of 3-butene-1-ol and 1-pentene-3-ol.

[0015] The allyl modified phenolic resin is prepared by the following steps:

[0016] A1. Stirring the linear phenolic resin and n-butanol at a temperature of 70 to 80° C. for 2 to 3 h to obtain a phenolic resin solution;

[0017] A2. Add a catalyst to the phenolic resin solution, add allyl chloride at a temperature below 45° C. to react by stirring, and obtain an allyl-modified phenolic resin after filtering, washing, and removing the solvent.

[0018] Since the boiling point of allyl chloride is 45° C., if allyl chloride is added at 80-90° C., it will boil rapidly and cause allyl chloride loss. Therefore, the present invention first cools the reaction system to below 45° C., and then raises the temperature after the addition of allyl chloride is completed to increase the reaction rate.

[0019] In step A1, the mass ratio of the linear phenolic resin to n-butanol is 1:0.8-1.2.

[0020] In step A2, adding a catalyst to the phenolic resin solution and adding allyl chloride at a temperature below 45° C. for stirring reaction comprises the following steps:

[0021] B1, adding a catalyst to the phenolic resin solution, keeping the temperature at 80-90° C. for 1-1.5 h to obtain a reaction system;

[0022] B2. Add allyl chloride dropwise into the reaction system at 35-45°C, then raise the temperature to 80-90°C and stir for 5.5-6.5 h.

[0023] In step B1, the catalyst is KOH, and the mass ratio of the catalyst to the linear phenolic resin in the phenolic resin solution is 1:5-6.

[0024] In step B2, the mass ratio of the allyl chloride to the linear phenolic resin in the reaction system is 1:1-2.

[0025] In step A2, the washing is performed multiple times with deionized water.

[0026] As a general inventive concept, the present invention also provides an application of the above-mentioned method for synthesizing a tantalum carbide precursor containing unsaturated bonds in the preparation of tantalum carbide ceramic materials.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] The invention discloses a method for synthesizing a tantalum carbide precursor containing an unsaturated bond. The method comprises the following steps: using an unsaturated alcohol to replace a saturated alcohol to synthesize a tantalum alkoxide (i.e., an unsaturated alcohol solution in which a tantalum salt is dissolved); using the tantalum alkoxide as a tantalum source and an allyl phenolic resin as a carbon source; and synthesizing a TaC precursor through a free radical copolymerization reaction. More C=C bond cross-linking sites are introduced into the precursor, so that the tantalum source and the carbon source are mixed in the molecule through a C=C bond addition polymerization reaction, thereby improving the cross-linking degree of the precursor. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is the infrared spectrum of the tantalum carbide precursor synthesized in Example 2 and Example 5.

[0030] Figure 2This is the hydrogen nuclear magnetic resonance spectrum of the tantalum carbide precursor synthesized in Example 2 and Example 5.

[0031] Figure 3 TG curves of tantalum carbide precursors synthesized in Examples 1 to 6 and Comparative Examples 1 and 2.

[0032] Figure 4 This is the infrared spectrum of the tantalum carbide precursor synthesized in Comparative Example 1 and Comparative Example 2. DETAILED DESCRIPTION

[0033] The present invention will be described in further detail below. Unless otherwise specified, the instruments or materials used in the present invention are commercially available.

[0034] Embodiment 1:

[0035] A method for synthesizing a tantalum carbide precursor containing an unsaturated bond in this embodiment comprises the following steps:

[0036] S1. Preparation of raw materials

[0037] 3-Butene-1-oltantalum is prepared by the following steps: 100 g of TaCl5 is dissolved in 200 ml of 3-butene-1-ol under nitrogen conditions at room temperature, and magnetic stirring is performed for 1 h to complete the reaction to obtain 3-butene-1-oltantalum.

[0038] The allyl modified phenolic resin solution is prepared by the following steps:

[0039] A1. Dissolve 100 g of linear phenolic resin in 100 g of n-butanol, heat to 70°C and stir for 2 h to fully dissolve the phenolic resin to obtain a phenolic resin solution.

[0040] A2. Add 20 g of KOH to the phenolic resin solution, heat it to 80°C, keep it warm for 1 h, then cool it to 40°C, add 50 g of allyl chloride dropwise to the flask, heat it to 80°C again after the addition is complete, and continue the reaction for 6 h until a large amount of precipitate is produced. After filtering to obtain a clear solution, wash it three times with distilled water, and finally remove most of the solvent by reduced pressure distillation to obtain a red allyl-modified phenolic resin solution.

[0041] S2. Free Radical Copolymerization

[0042] Under nitrogen conditions, 3-butene-1-ol tantalum was used as a tantalum source, and an allyl-modified phenolic resin (AN resin for short) solution was used as a carbon source. The carbon source and the tantalum source were mixed in a mass ratio of m(AN):m(TaCl5)=0.4, and stirred at room temperature for 1 h. Then, 7 wt% of didodecanoyl peroxide of the total mass of the carbon source and the tantalum source was added, and the temperature was raised to 70°C for reaction for 13 h to obtain the tantalum carbide precursor containing unsaturated bonds in this embodiment (denoted as PTC-Butene-0.4 precursor, in liquid state).

[0043] The synthesis mechanism of the PTC-Butene-0.4 precursor of this embodiment is shown in the following formula: 3-butene-1-tantalum alcohol is mostly tetrasubstituted due to the steric hindrance effect, and the allyl group in the AN resin may be connected to the phenol-OH or to the benzene ring skeleton. When the didodecanol peroxide initiator is added and the temperature is raised to above 70°C, the initiator decomposes to produce free radicals, resulting in a free radical copolymerization reaction between the tantalum alcohol salt and the AN resin, thereby achieving uniform mixing of the tantalum source and the carbon source in the precursor molecule.

[0044]

[0045] The PTC-Butene-0.4 precursor of this example was pyrolyzed at 1400°C to obtain TaC powder, in which the oxygen content of TaC powder was 2.26 wt%, and the free carbon content was almost undetectable. Figure 3 As shown in the figure, with the increase of pyrolysis temperature, the precursor is transformed into TaC powder through inorganic transformation, oxide crystallization and carbon thermal reduction processes in sequence, and the ceramic yield at 1400℃ is 51.54%.

[0046] Embodiment 2:

[0047] A method for synthesizing a tantalum carbide precursor containing an unsaturated bond in this embodiment comprises the following steps:

[0048] S1. Preparation of raw materials

[0049] 3-Butene-1-oltantalum is prepared by the following steps: 100 g of TaCl5 is dissolved in 200 ml of 3-butene-1-ol under nitrogen conditions at room temperature, and magnetic stirring is performed for 1 h to complete the reaction to obtain 3-butene-1-oltantalum.

[0050] The allyl modified phenolic resin solution is prepared by the following steps:

[0051] A1. Dissolve 100 g of linear phenolic resin in 100 g of n-butanol, heat to 70°C and stir for 2 h to fully dissolve the phenolic resin to obtain a phenolic resin solution.

[0052] A2. Add 20 g of KOH to the phenolic resin solution, raise the temperature to 80°C, keep warm for 1 h, then cool to 40°C, add 66.7 g of allyl chloride dropwise, raise the temperature to 80°C again after the addition is complete, and continue the reaction for 6 h until a large amount of precipitate is produced. After filtering to obtain a clear solution, wash it three times with distilled water, and finally remove most of the solvent by reduced pressure distillation to obtain a red allyl-modified phenolic resin (AN) solution.

[0053] S2. Free Radical Copolymerization

[0054] Under nitrogen conditions, 3-butene-1-ol tantalum and AN resin solution were mixed in a ratio of m(AN):m(TaCl5)=0.5, and after stirring at room temperature for 1 h, 7 wt% of the total mass of carbon source and tantalum source was added. The temperature was raised to 80°C and reacted for 13 h to obtain the tantalum carbide precursor containing unsaturated bonds in this example (denoted as PTC-Butene-0.5 precursor, in liquid state).

[0055] The infrared spectrum of the PTC-Butene-0.5 precursor of this example is as follows Figure 1 As shown, 1640 cm -1 The C=C stretching vibration peak indicates that an unsaturated double bond is introduced into the precursor.

[0056] The PTC-Butene-0.5 precursor of this embodiment was subjected to a nuclear magnetic resonance hydrogen spectrum test, and the test results are as follows: Figure 2 As shown in the figure, the resonance peaks at 4.9-5.2 ppm and 5.7-5.9 ppm correspond to the H on carbon 1 and carbon 2 of the C=C bond at the end, respectively, proving once again that the C=C bond was introduced into the precursor. The characteristic peak at 2.1-2.4 ppm belongs to the H on the methylene near the C=C end of 3-butene-1-alkanol tantalum, and the resonance peaks at 3.2-3.5 ppm and 3.6-4.1 ppm correspond to the H on the carbon 3 of the allyl group directly connected to the benzene ring and the H on the methylene between the benzene rings, respectively, proving that 3-butene-1-alkanol tantalum and AN resin were introduced into the PTC molecular structure, achieving the mixing of tantalum source and carbon source in the precursor molecule.

[0057] The PTC-Butene-0.5 precursor of this embodiment is pyrolyzed at 1400°C to obtain TaC powder. The oxygen content of the TaC powder is 0.89 wt%, the free carbon content is 2.91 wt%, and the thermogravimetric curve of the precursor is as follows: Figure 3 As shown, the ceramic yield at 1400℃ is 50.13%.

[0058] Embodiment 3:

[0059] A method for synthesizing a tantalum carbide precursor containing an unsaturated bond in this embodiment comprises the following steps:

[0060] S1. Preparation of raw materials

[0061] 3-Butene-1-oltantalum is prepared by the following steps: 100 g of TaCl5 is dissolved in 200 ml of 3-butene-1-ol under nitrogen conditions at room temperature, and magnetic stirring is performed for 1 h to complete the reaction to obtain 3-butene-1-oltantalum.

[0062] The allyl modified phenolic resin solution is prepared by the following steps:

[0063] A1. Dissolve 100 g of linear phenolic resin in 100 g of n-butanol, heat to 70°C and stir for 2 h to fully dissolve the phenolic resin to obtain a phenolic resin solution.

[0064] A2. Add 20 g of KOH to the phenolic resin solution, heat it to 80°C, keep it warm for 1 hour, then cool it to 40°C, add 100 g of allyl chloride dropwise to the flask, heat it to 80°C again after the addition is complete, and continue the reaction for 6 hours until a large amount of precipitation is produced. After filtering to obtain a clear solution, wash it with distilled water three times, and finally remove most of the solvent by vacuum distillation to obtain a red allyl-modified phenolic resin (AN) solution.

[0065] S2. Free Radical Copolymerization

[0066] Under nitrogen conditions, 3-butene-1-ol tantalum and AN resin were mixed in a ratio of m(AN):m(TaCl5)=0.7, and after stirring at room temperature for 1 h, 7 wt% of the total mass of carbon source and tantalum source was added. The temperature was raised to 80°C and reacted for 13 h to obtain the tantalum carbide precursor containing unsaturated bonds in this example (denoted as PTC-Butene-0.7 precursor, in liquid state).

[0067] The PTC-Butene-0.7 precursor of this embodiment is pyrolyzed at 1400°C to obtain TaC powder. The oxygen content of the TaC powder is 0.87 wt%, the free carbon content is 8.29 wt%, and the thermogravimetric curve of the precursor is as follows: Figure 3 As shown, the ceramic yield at 1400℃ is 48.52%.

[0068] Embodiment 4:

[0069] A method for synthesizing a tantalum carbide precursor containing an unsaturated bond in this embodiment comprises the following steps:

[0070] S1. Preparation of raw materials

[0071] 1-Pentene-3-oltantalum is prepared by the following steps: 100 g of TaCl5 is dissolved in 250 ml of 1-pentene-3-ol at room temperature under nitrogen conditions, and magnetic stirring is performed for 1 h to complete the reaction, thereby obtaining 1-pentene-3-oltantalum;

[0072] The allyl modified phenolic resin solution is prepared by the following steps:

[0073] A1. Dissolve 100 g of linear phenolic resin in 100 g of n-butanol, heat to 70°C and stir for 2 h to fully dissolve the phenolic resin to obtain a phenolic resin solution.

[0074] A2. Add 20 g of KOH to the phenolic resin solution, heat it to 80°C, keep it warm for 1 hour, then cool it to 40°C, add 50 g of allyl chloride dropwise to the flask, heat it to 80°C again after the addition is complete, and continue the reaction for 6 hours until a large amount of precipitation is produced. After filtering to obtain a clear solution, wash it three times with distilled water, and finally remove most of the solvent by vacuum distillation to obtain a red allyl-modified phenolic resin (AN resin) solution.

[0075] S2. Free Radical Copolymerization

[0076] Under nitrogen conditions, 1-pentene-3-tantalum alcohol and AN resin were mixed in a ratio of m(AN):m(TaCl5)=0.4, stirred at room temperature for 1 h, and then 5 wt% of the total mass of carbon source and tantalum source was added. The temperature was raised to 80°C for reaction for 1 h to obtain the tantalum carbide precursor containing unsaturated bonds in this embodiment (referred to as PTC-Pentene-0.4 precursor, in solid state). Compared with 3-butene-1-tantalum alcohol, the free radical copolymerization reaction of 1-pentene-3-tantalum alcohol is faster and can be completed in a shorter reaction time.

[0077] The PTC-Pentene-0.4 precursor of this example was pyrolyzed at 1400°C to obtain TaC powder. The oxygen content in the TaC powder was 3.53 wt %, and free carbon was almost undetectable. The thermogravimetric curve of the precursor was as follows: Figure 3 As shown, the ceramic yield at 1400℃ is 61.55%.

[0078] The synthesis mechanism of the PTC-Pentene-0.4 precursor of this embodiment is shown in the following formula: 1-pentene-3-tantalum alkoxide and AN resin are reacted by free radical copolymerization to synthesize TaC precursor. Since 1-pentene-3-tantalum alkoxide contains side chains, it has a greater steric hindrance effect than 3-butene-1-tantalum alkoxide, and most of them undergo tri-substitution.

[0079]

[0080] Embodiment 5:

[0081] A method for synthesizing a tantalum carbide precursor containing an unsaturated bond in this embodiment comprises the following steps:

[0082] S1. Preparation of raw materials

[0083] 1-Pentene-3-oltantalum is prepared by the following steps: 100 g of TaCl5 is dissolved in 250 ml of 1-pentene-3-ol at room temperature under nitrogen conditions, and magnetic stirring is performed for 1 h to complete the reaction, thereby obtaining 1-pentene-3-oltantalum;

[0084] The allyl modified phenolic resin solution is prepared by the following steps:

[0085] A1. Dissolve 100 g of linear phenolic resin in 100 g of n-butanol, heat to 70°C and stir for 2 h to fully dissolve the phenolic resin to obtain a phenolic resin solution.

[0086] A2. Add 20 g of KOH to the phenolic resin solution, raise the temperature to 80°C, keep warm for 1 h, then cool to 40°C, add 66.7 g of allyl chloride dropwise to the flask, raise the temperature to 80°C again after the addition is complete, and continue the reaction for 6 h until a large amount of precipitate is produced. After filtering to obtain a clear solution, wash it three times with distilled water, and finally remove most of the solvent by reduced pressure distillation to obtain a red allyl-modified phenolic resin (AN) solution.

[0087] S2. Free Radical Copolymerization

[0088] Under nitrogen conditions, 1-pentene-3-ol tantalum and AN resin were mixed in a ratio of m(AN):m(TaCl5)=0.6, and after stirring at room temperature for 1 h, 5 wt% of the total mass of carbon source and tantalum source was added. The temperature was raised to 80°C and reacted for 1 h to obtain the tantalum carbide precursor containing unsaturated bonds in this example (denoted as PTC-Pentene-0.6 precursor, in solid state).

[0089] The PTC-Pentene-0.6 precursor of this embodiment is pyrolyzed at 1400°C to obtain TaC powder. The oxygen content of the TaC powder is 1.23 wt%, the free carbon content is 1.59 wt%, and the thermogravimetric curve of the precursor is as follows: Figure 3 As shown, the ceramic yield at 1400℃ is 58.01%.

[0090] The infrared spectrum of the PTC-Pentene-0.6 precursor of this example is as follows Figure 1 As shown, 1640 cm -1 The C=C stretching vibration peak indicates that unsaturated double bonds are introduced into the precursor, and the intensity of the C=C bond characteristic peak is lower than that of PTC-Butene, indicating that PTC-Pentene has a higher degree of cross-linking and a more complete free radical copolymerization reaction.

[0091] The PTC-Pentene-0.6 precursor of this embodiment was subjected to a nuclear magnetic resonance hydrogen spectrum test, and the test results are as follows: Figure 2 As shown, the types of characteristic peaks contained are similar to those of PTC-Butene-0.5 in Example 2, and the uniform mixing of the tantalum source and the carbon source in the precursor molecule is also achieved. The intensity of the C=C bond characteristic peak of PTC-Pentene-0.6 in Example 5 is lower than that of PTC-Butene-0.5 in Example 2, which once again proves that PTC-Pentene-0.6 in Example 5 has a higher degree of crosslinking, and therefore is solid after the free radical copolymerization reaction, while PTC-Butene-0.5 in Example 2 is liquid due to the lower degree of crosslinking.

[0092] Embodiment 6:

[0093] A method for synthesizing a tantalum carbide precursor containing an unsaturated bond in this embodiment comprises the following steps:

[0094] S1. Preparation of raw materials

[0095] 1-Pentene-3-oltantalum is prepared by the following steps: 100 g of TaCl5 is dissolved in 250 ml of 1-pentene-3-ol under nitrogen conditions at room temperature, and magnetic stirring is performed for 1 h to complete the reaction to obtain 1-pentene-3-oltantalum.

[0096] The allyl modified phenolic resin solution is prepared by the following steps:

[0097] A1. Dissolve 100 g of linear phenolic resin in 100 g of n-butanol, heat to 70°C and stir for 2 h to fully dissolve the phenolic resin to obtain a phenolic resin solution.

[0098] A2. Add 20 g of KOH to the phenolic resin solution, heat it to 80°C, keep it warm for 1 hour, then cool it to 40°C, add 100 g of allyl chloride dropwise to the flask, heat it to 80°C again after the addition is complete, and continue the reaction for 6 hours until a large amount of precipitation is produced. After filtering to obtain a clear solution, wash it with distilled water three times, and finally remove most of the solvent by vacuum distillation to obtain a red allyl-modified phenolic resin (AN) solution.

[0099] S2. Free Radical Copolymerization

[0100] Under nitrogen conditions, 1-pentene-3-ol tantalum and AN were mixed in a ratio of m(AN):m(TaCl5)=0.8, and after stirring at room temperature for 1 h, 5 wt% of the total mass of the carbon source and the tantalum source was added with didodecanoyl peroxide, and the temperature was raised to 80°C for reaction for 1 h to obtain the tantalum carbide precursor containing unsaturated bonds in this example (denoted as PTC-Pentene-0.8 precursor, in a solid state).

[0101] The PTC-Pentene-0.8 precursor of this embodiment is pyrolyzed at 1400°C to obtain TaC powder. The oxygen content of the TaC powder is 0.99 wt%, the free carbon content is 6.96 wt%, and the thermogravimetric curve of the precursor is as follows: Figure 3 As shown in the figure, the yield of ceramics at 1400℃ is 56.49%. Due to the higher degree of cross-linking of PTC-Pentene and less mass loss during the inorganic process, the yield of ceramics at 1400℃ is generally higher than that of PTC-Butene.

[0102] Comparative Example 1:

[0103] A tantalum carbide precursor synthesis method of this comparative example comprises the following steps:

[0104] S1. Preparation of tantalum source, including the following steps:

[0105] A1. Under nitrogen conditions at room temperature, dissolve 100 g of TaCl5 in 128 ml of propanol and stir magnetically for 1 h to complete the reaction to obtain tantalum propoxide.

[0106] A2. Add 86 ml of acetylacetone to the tantalum propoxide solution, raise the temperature to 60°C and react for 1 h to generate a tantalum propoxide complex, which reduces the hydrolysis activity of tantalum propoxide.

[0107] A3. Add 10 ml of deionized water to the tantalum propoxide complex and react at 60°C for 1 h to allow the tantalum propoxide complex to undergo controllable hydrolysis to obtain a tantalum source.

[0108] S2, high temperature cross-linking curing reaction

[0109] The hydrolyzed tantalum propanol complex was used as the tantalum source, and 50 ml of a 50% by volume ethanol solution of a linear phenolic resin was used as the carbon source. The carbon source was added to the tantalum source and stirred for 30 min to mix the tantalum source and the carbon source evenly. The mixture was vacuum distilled at 60°C for 30 min to remove excess solvent, and the temperature was raised to 200°C for reaction for 2 h to fully cross-link and solidify, thereby obtaining the tantalum carbide precursor of this comparative example (referred to as PTC-Propanol precursor).

[0110] The thermogravimetric curve of the PTC-Propanol precursor of this comparative example is as follows Figure 3 As shown, TaC powder was obtained after pyrolysis at 1400 °C, and the ceramic yield was 45.61%.

[0111] Comparative Example 2:

[0112] A tantalum carbide precursor synthesis method of this comparative example comprises the following steps:

[0113] S1. Preparation of tantalum source, including the following steps:

[0114] A1. Under nitrogen conditions at room temperature, dissolve 100 g of TaCl5 in 152 ml of n-butanol and stir magnetically for 1 h to complete the reaction to obtain tantalum n-butoxide.

[0115] A2. Add 58 ml of acetylacetone to the n-butanol solution, raise the temperature to 60°C and react for 1 h to generate tantalum n-butoxide complex and reduce the hydrolysis activity of tantalum n-butoxide.

[0116] A3. Add 15 ml of deionized water to the tantalum n-butoxide complex and react at 60°C for 1 h to allow the tantalum n-butoxide complex to undergo controllable hydrolysis to obtain a tantalum source.

[0117] S2, high temperature cross-linking curing reaction

[0118] The hydrolyzed n-butoxide tantalum complex was used as the tantalum source, and 50 ml of a 50% by volume ethanol solution of a linear phenolic resin was used as the carbon source. The carbon source was added to the tantalum source and stirred for 30 min to evenly mix the tantalum source and the carbon source. The mixture was vacuum distilled at 60°C for 30 min to remove excess solvent, and the temperature was raised to 200°C for reaction for 2 h to fully crosslink and solidify, thereby obtaining the tantalum carbide precursor of this comparative example (referred to as PTC-Butanol precursor).

[0119] The thermogravimetric curve of the PTC-Butanol precursor of this comparative example is as follows Figure 3 As shown, TaC powder was obtained after pyrolysis at 1400 °C, and the ceramic yield was 43.31%.

[0120] The infrared spectra of the PTC-Propanol precursor of Comparative Example 1 and the PTC-Butanol precursor of Comparative Example 2 are as follows: Figure 4 As shown in Figure 2, due to the conjugated structure formed by acetylacetone and tantalum, the stretching vibration peaks of C=O, C=C, and C-CH3 red-shift to 1567 cm -1 、1540 cm -1 and 1287 cm -1 , Ta-OC structure at 1038 cm -1 The stretching vibration peak at 878 cm -1 The strong peak at is the stretching vibration peak of the Ta-O-Ta main chain formed after dehydration condensation.

[0121] Since Comparative Examples 1 and 2 use saturated alcohols, which do not contain C=C bonds in their molecular structures, free radicals cannot be generated by breaking the C=C bonds, i.e., free radical copolymerization cannot occur. In the PTC-Propanol precursor of Comparative Example 1 and the PTC-Butanol precursor of Comparative Example 2, which are synthesized from saturated alcohols by dehydration condensation, the tantalum source and the carbon source are mixed only by mechanical stirring, and the target element is not mixed in the precursor molecules, and the 1640 cm-1 chromatogram cannot be detected in the infrared spectrum. -1 The characteristic peak of C=C bond at the wave number indicates that the main chain structure does not contain unsaturated bonds as cross-linking sites, the precursor has a low degree of cross-linking, and the mass loss during pyrolysis is greater, and the ceramic yield is also lower (the ceramic yield is the mass ratio of the pyrolysis product to the precursor, and the ceramic yield can reflect the mass loss during pyrolysis). This proves that the TaC precursor based on the free radical copolymerization method of the present invention has better performance.

[0122] Although the present invention has been disclosed as above with preferred embodiments, it is not intended to limit the present invention. Any technician familiar with the art can make many possible changes and modifications to the technical solution of the present invention by using the technical content disclosed above without departing from the scope of the technical solution of the present invention, or modify it into an equivalent embodiment of equivalent changes. Therefore, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present invention without departing from the content of the technical solution of the present invention should fall within the scope of protection of the technical solution of the present invention.

Claims

1. A method for synthesizing a tantalum carbide precursor containing an unsaturated bond, characterized in that: The following steps are involved: Tantalum alkoxide is used as a tantalum source, and allyl-modified phenolic resin is used as a carbon source. The tantalum source and the carbon source are mixed and stirred, a free radical initiator is added, and a free radical copolymerization reaction is carried out at a temperature of 70 to 80°C for 1 to 13 hours to obtain a tantalum carbide precursor containing an unsaturated bond. The tantalum alkoxide is obtained by a substitution reaction between a tantalum salt and an unsaturated alcohol containing a double bond in the molecule. The mass ratio of the carbon source to the tantalum source satisfies the carbon source: tantalum salt in the tantalum source = 0.4 to 0.8:1, and the unsaturated alcohol is one or more of 4-pentene-1-ol, 4-pentene-2-ol, 3-butene-1-ol and 1-pentene-3-ol.

2. The method for synthesizing a tantalum carbide precursor containing an unsaturated bond according to claim 1, characterized in that: The free radical initiator is one or more of dicumyl peroxide, azobisisobutyronitrile, azobisisoheptanoyl peroxide and didodecanoyl peroxide.

3. The method for synthesizing a tantalum carbide precursor containing an unsaturated bond according to claim 1, characterized in that: The tantalum alkoxide is prepared by the following steps: mixing tantalum salt and unsaturated alcohol in a molar ratio of 1:6 to 10, and stirring for 0.5 to 1 h; The tantalum salt is tantalum pentachloride.

4. The method for synthesizing a tantalum carbide precursor containing an unsaturated bond according to claim 1, characterized in that: The allyl modified phenolic resin is prepared by the following steps: A1. Stirring the linear phenolic resin and n-butanol at a temperature of 70 to 80° C. for 2 to 3 h to obtain a phenolic resin solution; A2. Add a catalyst to the phenolic resin solution, add allyl chloride at a temperature below 45° C. to react by stirring, and obtain an allyl-modified phenolic resin after filtering, washing, and removing the solvent.

5. The method for synthesizing a tantalum carbide precursor containing an unsaturated bond according to claim 4, characterized in that: In step A1, the mass ratio of the linear phenolic resin to n-butanol is 1:0.8-1.

2.

6. The method for synthesizing a tantalum carbide precursor containing an unsaturated bond according to claim 4, characterized in that: In step A2, adding a catalyst to the phenolic resin solution and adding allyl chloride at a temperature below 45° C. for stirring reaction comprises the following steps: B1, adding a catalyst to the phenolic resin solution, keeping the temperature at 80-90° C. for 1-1.5 h to obtain a reaction system; B2. Add allyl chloride dropwise into the reaction system at 35-45°C, then raise the temperature to 80-90°C and stir for 5.5-6.5 h.

7. The method for synthesizing a tantalum carbide precursor containing an unsaturated bond according to claim 6, characterized in that: In step B1, the catalyst is KOH, and the mass ratio of the catalyst to the linear phenolic resin in the phenolic resin solution is 1:5-6.

8. The method for synthesizing a tantalum carbide precursor containing an unsaturated bond according to claim 6, characterized in that: In step B2, the mass ratio of the allyl chloride to the linear phenolic resin in the reaction system is 1:1-2.

9. The method for synthesizing a tantalum carbide precursor containing an unsaturated bond according to claim 4, characterized in that: In step A2, the washing is performed multiple times with deionized water.

10. Use of the method for synthesizing a tantalum carbide precursor containing unsaturated bonds according to any one of claims 1 to 9 in preparing tantalum carbide ceramic materials.

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