Synthesis of (zrtati)c superhigh-temperature solid solution ceramic by a solvothermal polymer conversion ceramic method and method

Abstract

The application discloses a kind of (ZrTaTi) C superhigh-temperature solid solution ceramics synthesized by solvothermal polymer conversion ceramic method and method, belong to powder synthesis technical field.The method uses TaCl5, C 12 H 28 O4Zr and C 16 H 36 O4Ti respectively as tantalum source, zirconium source and titanium source precursor, with resin carbon as carbon source, (ZrTaTi) C precursor is successfully prepared by solvothermal method, then after high-temperature heat treatment, realize the complete conversion of polymer to single-phase solid solution ceramic, finally prepare nano (ZrTaTi) C superhigh-temperature ceramic solid solution.The application preparation process is simple, preparation period is short, preparation temperature is relatively low, suitable for mass production, has better application prospect.

Description

Technical Field

[0001] This invention belongs to the field of powder synthesis technology, specifically relating to a solvothermal polymer-conversion ceramic method for synthesizing (ZrTaTi)C ultra-high temperature solid solution ceramics and a method thereof. Background Technology

[0002] With the rapid development of aerospace technology, advanced high-speed aircraft have become a new strategic high ground in aerospace, and the development of new anti-oxidation and anti-ablation thermal structural materials for use in ultra-high temperature environments has become a key research direction in the aerospace field.

[0003] Ultra-high temperature ceramic materials have attracted widespread attention from scholars at home and abroad due to their excellent properties such as high melting point, high strength, good high-temperature stability and ablation resistance. Ultra-high temperature ceramics mainly include carbides, borides and nitrides of refractory transition metals. Among them, high-melting-point ultra-high temperature ceramic carbides such as ZrC (3540℃) are the most widely studied as ultra-high temperature ablation-resistant modifiers. However, due to the high melting point of its oxide (ZrO2: 2700℃), it is difficult for the particles to be fully sintered during the ablation process, and the resulting oxide layer often exhibits a loose, porous and discontinuous distribution (Y.Li,Y.Liu,C.Guo,Y.Chen,J.Liang,J.Zhang,J.Zhang,L.Guo,Ablation resistance of ZrC-based composite coating with multi-layer structure for carbon / carbon composite above 2200℃,Corros.Sci.207(2022)110600.). To further improve the ablation resistance of ZrC-based ceramic coatings in ultra-high temperature environments, second-phase materials are often added to modify them. For example, the ablation products of TaC and TiC (Ta2O5: 1800℃, TiO2: 1840℃) have relatively low melting points and can form a liquid oxide film during ablation, effectively filling the porous framework formed by ZrO2 (X.Pan,Y.Niu,T.Liu,X.Zhong,C.Li,M.Shi,X.Zheng,C.Ding,Ablation behaviors of ZrC-TiC coatings prepared by vacuum plasma spray:Above2000℃,J.Eur.Ceram.Soc.39(11)(2019)3292-3300.). Therefore, the additional introduction of TaC and TiC into the ZrC system can further improve its ablation resistance. In addition, researchers have found that compared with composite coatings of single carbides or multiple carbides, single-phase solid solution materials have superior physical and chemical properties, such as higher strength, better corrosion resistance and oxidation resistance. After oxidation and ablation, they generate multiphase oxides with better high-temperature stability, giving them better ablation resistance.

[0004] Currently, solid-state reaction methods are commonly used to prepare single-phase ultra-high temperature solid solution ceramics. This involves using a single carbide (or a corresponding oxide and inorganic carbon powder) as raw material and inducing a solid solution reaction through spark plasma sintering (SPS). E. Castle et al. prepared (HfTaZrTi)C and (HfTaZrNb)C ultra-high temperature carbides using a two-step sintering method via SPS. Compared to the mechanical properties of single carbides, the mechanical properties of the solid solution materials are significantly improved due to the solid solution strengthening effect caused by local lattice strain. Compared with single carbide (HfC, 31.5±1.3 GPa) and binary (Hf-Ta)C (32.9±1.8 GPa), the hardness of (Hf-Ta-Zr-Nb)C is significantly increased (36.1±1.6 GPa) (E. Castle, T. Csanádi, S. Grasso, J. Dusza, M. Reece, Processing and properties of high-entropy ultra-high temperature carbides, Sci. Rep. 8(1)(2018) 8609). However, this method involves a high-temperature and high-pressure process (>2000℃), and the solid solution grains will grow significantly during high-temperature sintering, forming micron-sized particles, which will have an adverse effect on the subsequent properties of the material (B. Du, Y. Liu, J. Xu, Y. Ouyang, Y. Cheng, T. Zhang, Fabrication and electromagnetic wave absorbing properties of the (Hf 0.25 Zr 0.25 Nb 0.25 Ta 0.25(See *C high-entropy ceramics*, *J. Alloys Compd.*, 969(2023) 172403.). Miao et al. prepared (Hf-Ta-Zr)C solid solution ceramics using a polymer-converted ceramic method with hafnium-tantalum ceramic precursors and ZrC precursors as raw materials. The heat treatment temperature was 1900℃, significantly lower than the preparation temperature of the solid-state reaction method (Q. Miao, Y. Fu, H. Chen, J. Zhang, J. Zhao, Y. Zhang, *Simultaneous enhancement of mechanical and ablation properties of C / C composites modified by (Hf-Ta-Zr)C solid solution ceramics*, *J. Eur. Ceram. Soc.*, 43(2023) 3182-3190). However, when using this method to prepare single-phase ultra-high temperature solid solution ceramics, the particle size of the obtained (Hf-Ta-Zr)C solid solution ceramics was still in the micrometer range.

[0005] The commonly used solid-state sintering method involves first uniformly dispersing the corresponding carbide (or corresponding oxide and inorganic carbon source) through ball milling or other methods, and then heat-treating it under high temperature and high pressure to induce a solid solution reaction and obtain a single-phase solid solution ceramic. This method usually has high requirements for equipment, and the reaction temperature is often higher than 2000℃. The high reaction temperature will result in larger particle size and a relatively wide size range of the product, which will have a certain negative impact on the final performance of the material.

[0006] Traditional multi-component solid solutions and high-entropy carbides typically exhibit low thermal conductivity, leading to severe stationary ablation due to their poor thermal conductivity and heat dissipation when used as ultra-high temperature ablation-resistant modifiers. Under prolonged and harsh aerodynamic heating, the materials' resistance to oxidation and ablation, as well as their mechanical load-bearing capacity, will significantly decrease. Nanomaterials possess extremely high theoretical thermal conductivity, making them easy to interlock in composite materials and form continuous and efficient thermal conduction pathways, significantly improving the thermal conductivity of composites even at low content. However, the tendency of nanomaterial powder to agglomerate and the high interfacial thermal resistance hinder the improvement of composite material thermal conductivity. If core-shell structured nanomaterial carbon-coated solid solution / high-entropy ceramic composites can be synthesized, it can effectively solve the problem of uneven dispersion of nanofillers, allowing the fillers to form interconnected thermal conduction pathways within the solid solution or high-entropy ceramic matrix, thereby improving the thermal conductivity of the composite material. Furthermore, the presence of the nanocarbon shell helps suppress grain growth in the solid solution / high-entropy ceramic during high-temperature heat treatment, resulting in grain refinement. Summary of the Invention

[0007] The purpose of this invention is to overcome the shortcomings of the prior art and provide a solvothermal polymer-conversion ceramic method for synthesizing (ZrTaTi)C ultra-high temperature solid solution ceramics, thereby solving the problems of large particle size and high preparation temperature in the prior art.

[0008] To achieve the above objectives, the present invention employs the following technical solution:

[0009] A method for synthesizing (ZrTaTi)C ultra-high temperature solid solution ceramics via a solvothermal polymer conversion ceramic method includes the following steps:

[0010] Step 1: Tantalum pentachloride, zirconium n-propoxide and tetrabutyl titanate are dissolved in anhydrous ethanol and ultrasonically dispersed to form a solution containing a transition metal source precursor.

[0011] Step 2: Dissolve the resin in anhydrous ethanol to form a carbon source solution;

[0012] Step 3: Mix the precursor solution containing the transition metal source and the carbon source solution, and disperse them by ultrasonication to form a reaction solution;

[0013] Step 4: Place the reaction solution in a reaction vessel for solvothermal reaction. After the reaction is completed, dry the reaction product to obtain (ZrTaTi)C ceramic precursor.

[0014] Step 5: Wrap the (ZrTaTi)C ceramic precursor in graphite paper, place it in a graphite crucible, and then place the graphite crucible in a heat treatment furnace. After reacting under an inert atmosphere, (ZrTaTi)C solid solution ceramic is obtained.

[0015] A further improvement of the present invention is that:

[0016] Preferably, in step 1, the atomic molar ratio of tantalum pentachloride, zirconium n-propoxide, and tetrabutyl titanate is 1:1:1.

[0017] Preferably, in step 2, the resin is a phenolic resin or an epoxy resin.

[0018] Preferably, in step 2, the amount of phenolic resin added is prepared according to a molar ratio of TaCl5 to phenolic resin of 1:1 to 2:1.

[0019] Preferably, in step 3, the ultrasonic dispersion time is 30-60 min.

[0020] Preferably, in step 4, the solvothermal reaction temperature is 140-180℃ and the solvothermal reaction time is 6-10h.

[0021] Preferably, in step 5, the heat treatment reaction temperature is 1900-2100℃ and the heat treatment time is 2h.

[0022] Preferably, in step 5, the heat treatment reaction atmosphere is an inert atmosphere.

[0023] A (ZrTaTi)C ultra-high temperature solid solution ceramic prepared by any of the above methods, wherein the (ZrTaTi)C ultra-high temperature solid solution ceramic is granular, including nearly spherical (ZrTaTi)C ultra-high temperature ceramic solid solution particles, and the (ZrTaTi)C ultra-high temperature ceramic solid solution particles are coated with a carbon layer.

[0024] Preferably, the average diameter of the granular ultra-high temperature solid solution ceramic particles is 500 nm.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] This invention discloses a method for synthesizing (ZrTaTi)C ultra-high temperature solid solution ceramics using a solvothermal polymer conversion ceramic method, employing TaCl5 and C. 12 H 28 O4Zr and C 16 H 36 Using O4Ti as tantalum, zirconium, and titanium precursors respectively, and resin carbon as the carbon source, a (ZrTaTi)C precursor was successfully prepared via a solvothermal method. Subsequent high-temperature heat treatment achieved a complete transformation of the polymer into a single-phase solid solution ceramic, ultimately yielding nanoscale (ZrTaTi)C ultra-high temperature solid solution ceramics. This invention features a simple preparation process, short preparation cycle, and relatively low preparation temperature, making it suitable for large-scale production and showing promising application prospects.

[0027] The solvothermal combined polymer-to-ceramic conversion method used in this invention can simultaneously leverage the advantages of both methods. It achieves uniform elemental distribution at the molecular scale and allows for control of the final product's microstructure by adjusting process parameters such as the precursor type, solvothermal reaction temperature, and reaction time. During the solvothermal synthesis of the (ZrTaTi)C precursor, as the solvothermal temperature and system pressure increase, the precursors TaCl5 and C... 12 H 28 O4Zr and C 16 H 36O4Ti initially dissolves in solution as ions or ion clusters, followed by hydrolysis and condensation reactions to form corresponding coordination aggregates. When the solute concentration exceeds the supersaturation concentration required for grain nucleation, crystal nuclei begin to precipitate. However, unlike other processes, the solute undergoes explosive nucleation during the solvothermal reaction, consuming a large amount of solute and shortening the subsequent growth cycle, ultimately resulting in a (ZrTaTi)C precursor with a smaller grain size. In subsequent heat treatment, the (ZrTaTi)C precursor first undergoes the removal of small molecules and some groups from its branches, completing the polymer-to-inorganic transformation to form inorganic compounds Ta2O5, ZrO2, and TiO2. With further increases in heat treatment temperature, the oxides undergo carbothermic reduction, gradually transforming into the corresponding carbides. Then, solid solution reactions occur between the carbides, ultimately forming a single-phase (ZrTaTi)C ultra-high temperature solid solution ceramic at 1900℃.

[0028] The method of the present invention, by preparing a process precursor, enables the preparation of (ZrTaTi)C ultra-high temperature solid solution ceramics with relatively low heat treatment temperature (below 2000℃), nanoscale particle size, and narrow size distribution.

[0029] The method of this invention, by changing the type of precursor raw material, can be widely applied to the preparation of various single-phase ultra-high temperature solid solution ceramics, and is easy to mass-produce, showing good application prospects. By combining the above two methods, single-phase ultra-high temperature solid solution ceramic materials containing transition metal components can be prepared.

[0030] The present invention also discloses a (ZrTaTi)C ultra-high temperature solid solution ceramic, which has near-spherical particles with a narrow particle size range and an average particle size of about 500 nm. When the particle size of the ultra-high temperature solid solution ceramic is reduced to the nanoscale, the material properties (such as mechanical properties, oxidation resistance, and ablation resistance) will also be significantly improved. Attached Figure Description

[0031] Figure 1 The XRD patterns of (ZrTaTi)C ultra-high temperature solid solution ceramics prepared by heat treatment at 1700℃, 1900℃ and 2100℃ respectively are shown.

[0032] Figure 2 SEM images of (ZrTaTi)C ultra-high temperature solid solution ceramics obtained after solvothermal reaction and heat treatment at 1700℃, 1900℃ and 2100℃, respectively.

[0033] In the figure, (a) shows the result after the solvothermal reaction; (b) shows the heat treatment temperature at 1700℃; (c) shows the heat treatment temperature at 1900℃; and (d) shows the heat treatment temperature at 2100℃.

[0034] Figure 3 This is a TEM image of (ZrTaTi)C ultra-high temperature solid solution ceramic obtained by heat treatment at 1900℃ using phenolic resin as a carbon source.

[0035] Among them, (a) is a high-angle annular dark-field scanning transmission electron micrograph; (b) is the corresponding surface scanning result.

[0036] Figure 4 These are SEM images of (ZrTaTi)C ultra-high temperature solid solution ceramics obtained directly by heat treatment at 1900℃ using the polymer conversion ceramic method without solvothermal reaction. Detailed Implementation

[0037] This invention first forms a (ZrTaTi)C precursor via a solvothermal method, and then achieves a complete transformation from the polymer precursor to a single-phase ultra-high temperature solid solution ceramic through high-temperature heat treatment, thus preparing a single-phase (ZrTaTi)C ultra-high temperature solid solution ceramic. Specifically, it includes the following steps:

[0038] Step 1: Add tantalum pentachloride (TaCl5) and zirconium propoxide (C) 12 H 28 O4Zr and tetrabutyl titanate C 16 H 36 O4Ti was dissolved in anhydrous ethanol, and the mixture was placed in an ultrasonic device to be fully dispersed until completely dissolved, forming a homogeneous emulsion; the atomic molar ratio of Zr:Ta:Ti in the mixture was 1:1:1.

[0039] Step 2: The resin is dissolved in anhydrous ethanol as a carbon source and dispersed for a certain period of time using an ultrasonic device to form a uniform carbon source solution; the resin carbon source used is one of phenolic resin and epoxy resin.

[0040] It should be noted that the carbon source in this invention is limited to resin, which enables the final particles to be nearly spherical, while other carbon sources are difficult to achieve this effect.

[0041] Step 3: Add the carbon source solution obtained in Step 2 to the homogeneous emulsion obtained in Step 1, and disperse it thoroughly in an ultrasonic device to form a homogeneous reaction solution; the reaction time is 30-60 min. The molar ratio of TaCl5 to phenolic resin in the emulsion is 1:1 to 2:1.

[0042] Step 4: Transfer the reaction solution obtained in Step 3 to a 100mL reactor for a solvothermal reaction. After a certain reaction time, place it in a forced-air drying oven for thorough drying to remove the remaining solvent from the product, obtaining the (ZrTaTi)C ceramic precursor. The solvothermal reaction temperature is 140-180℃, and the reaction time is 6-10h. The solvothermal reaction involves certain pressure and temperature, thus enabling the formation of crystal nuclei.

[0043] It should be noted that, during this reaction, because the solvothermal reaction takes place in a reactor with certain temperature and pressure, a large number of nucleation sites can be formed in a short period of time.

[0044] The (ZrTaTi)C ceramic precursor particles formed in this step are smaller than 100 nm in size, and therefore some agglomeration occurs between the particles.

[0045] Step 5: Wrap the dried (ZrTaTi)C ceramic precursor in graphite paper and place it in a graphite crucible. Put the graphite crucible into a high-temperature heat treatment furnace and react at 1900-2100℃ for 2 hours under an inert atmosphere to prepare (ZrTaTi)C ultra-high temperature solid solution ceramic.

[0046] It should be noted that during the heat treatment process, if the heat treatment time is too short or the heat treatment temperature is too low, it is difficult to generate pure-phase (ZrTaTi)C ultra-high temperature solid solution ceramics. On the other hand, if the heat treatment time is too long or the heat treatment temperature is too high, the resulting ultra-high temperature ceramic grains are likely to be large.

[0047] The single-phase (ZrTaTi)C ultra-high temperature solid solution ceramic provided by this invention consists of nearly spherical particles with a core-shell structure. The core is a (ZrTaTi)C ultra-high temperature ceramic solid solution, and the outer shell is a nano-carbon layer. The average particle size is approximately 500 nm. The specific process is as follows:

[0048] To better understand the present invention, the technical solution of the present invention will be further described below with reference to specific embodiments.

[0049] Example 1

[0050] Step 1: Mix TaCl5 and C in a molar ratio of 1:1:1. 12 H 28 O4Zr and C 16 H 36 O4Ti was dissolved in 50 mL of anhydrous ethanol. The mixture was then placed in an ultrasonic device to be fully dispersed until completely dissolved, forming a uniform white emulsion.

[0051] Step 2: Weigh a certain amount of phenolic resin (C6H6O)n·(CH2O)n according to the molar ratio of TaCl5 and phenolic resin of 1:1, and disperse it in 10mL of anhydrous ethanol. Sonicate the mixture for 30min until it is completely dissolved, forming a homogeneous orange-yellow solution.

[0052] Step 3: Add the phenolic resin solution obtained in Step 2 to the homogeneous emulsion obtained in Step 1. The solution turns orange-yellow instantly. Disperse the solution in an ultrasonic device for 30 minutes to form a homogeneous solution.

[0053] Step 4: Transfer the homogeneous solution obtained in Step 3 to a 100 mL reaction vessel for solvothermal reaction at 160 °C for 8 h. After the reaction is completed, take out the product and dry it thoroughly in an 80 °C forced-air drying oven to remove the residual solvent in the product, and obtain the (ZrTaTi)C precursor.

[0054] Step 5: Wrap the (ZrTaTi)C precursor obtained in Step 4 with graphite paper, place it in a graphite crucible, and place the graphite crucible in a heat treatment furnace. React at 1900℃ for 2 hours under inert gas protection to obtain (ZrTaTi)C ultra-high temperature solid solution ceramic.

[0055] from Figure 1 As can be seen from the data, single-phase (ZrTaTi)C ultra-high temperature solid solution ceramics were prepared by using phenolic resin as a carbon source and heat treatment at 1900℃. No diffraction peaks of related oxides were observed, indicating that single-phase (ZrTaTi)C ultra-high temperature solid solution ceramics were successfully prepared by solvothermal combined with polymer conversion ceramic method. Figure 2 As can be seen in (c), using phenolic resin as a carbon source can produce (ZrTaTi)C ultra-high temperature solid solution ceramics with uniform size distribution and nanoscale dimensions. Figure 3 (a) It can be seen that the (ZrTaTi)C ultra-high temperature solid solution ceramic is uniformly surrounded by a nano-carbon layer unique to polymer-converted ceramics, forming a unique core-shell structure ceramic particle. From Figure 3 (b) It can be seen that Zr, Ta, Ti and C are uniformly distributed at the nanoscale, and there is no elemental segregation or phase separation.

[0056] Example 2:

[0057] Step 1: Mix TaCl5 and C in a molar ratio of 1:1:1. 12 H 28 O4Zr and C 16 H 36 O4Ti was dissolved in 50 mL of anhydrous ethanol. The mixture was then placed in an ultrasonic device to be fully dispersed until completely dissolved, forming a uniform white emulsion.

[0058] Step 2: Weigh out phenolic resin (C6H6O)n·(CH2O)n according to the molar ratio of TaCl5 to phenolic resin of 2:1, disperse it in 10mL of anhydrous ethanol, and sonicate for 30min until completely dissolved to form a homogeneous orange-yellow solution.

[0059] Step 3: Add the phenolic resin solution obtained in Step 2 to the homogeneous emulsion obtained in Step 1. The solution turns orange-yellow instantly. Disperse the solution in an ultrasonic device for 30 minutes to form a homogeneous solution.

[0060] Step 4: Transfer the homogeneous solution obtained in Step 3 to a 100 mL reaction vessel for solvothermal reaction at 160 °C for 8 h. After the reaction is completed, take out the product and dry it thoroughly in an 80 °C forced-air drying oven to remove the residual solvent in the product, and obtain the (ZrTaTi)C precursor.

[0061] Step 5: Wrap the (ZrTaTi)C precursor obtained in Step 4 with graphite paper, place it in a graphite crucible, and place the graphite crucible in a heat treatment furnace. React at 1900℃ for 2 hours under inert gas protection to obtain (ZrTaTi)C ultra-high temperature solid solution ceramic.

[0062] Example 3:

[0063] Step 1: Mix TaCl5 and C in a molar ratio of 1:1:1. 12 H 28 O4Zr and C 16 H 36 O4Ti was dissolved in 50 mL of anhydrous ethanol. The mixture was then placed in an ultrasonic device to be fully dispersed until completely dissolved, forming a uniform white emulsion.

[0064] Step 2: Weigh a certain amount of epoxy resin (C) according to a 1:1 molar ratio of TaCl5 to epoxy resin. 11 H 12 O3)n was dispersed in 10 mL of anhydrous ethanol and ultrasonically dispersed for 30 min until completely dissolved, forming a homogeneous orange-yellow solution.

[0065] Step 3: Add the epoxy resin solution obtained in Step 2 to the homogeneous emulsion obtained in Step 1. The solution turns orange-yellow instantly. Disperse the solution in an ultrasonic device for 30 minutes to form a homogeneous solution.

[0066] Step 4: Transfer the homogeneous solution obtained in Step 3 to a 100 mL reaction vessel for solvothermal reaction at 160 °C for 8 h. After the reaction is completed, take out the product and dry it thoroughly in an 80 °C forced-air drying oven to remove the residual solvent in the product, and obtain the (ZrTaTi)C precursor.

[0067] Step 5: Wrap the (ZrTaTi)C precursor obtained in Step 4 with graphite paper, place it in a graphite crucible, and place the graphite crucible in a heat treatment furnace. React at 1900℃ for 2 hours under inert gas protection to obtain (ZrTaTi)C ultra-high temperature solid solution ceramic.

[0068] Example 4

[0069] Step 1: Mix TaCl5 and C in a molar ratio of 1:1:1. 12 H 28 O4Zr and C 16 H 36 O4Ti was dissolved in 50 mL of anhydrous ethanol. The mixture was then placed in an ultrasonic device to be fully dispersed until completely dissolved, forming a uniform white emulsion.

[0070] Step 2: Weigh a certain amount of phenolic resin (C6H6O)n·(CH2O)n according to the molar ratio of TaCl5 and phenolic resin of 1:1, and disperse it in 10mL of anhydrous ethanol. Sonicate the mixture for 30min until it is completely dissolved, forming a homogeneous orange-yellow solution.

[0071] Step 3: Add the phenolic resin solution obtained in Step 2 to the homogeneous emulsion obtained in Step 1. The solution turns orange-yellow instantly. Disperse the solution in an ultrasonic device for 40 minutes to form a homogeneous solution.

[0072] Step 4: Transfer the homogeneous solution obtained in Step 3 to a 100 mL reaction vessel for solvothermal reaction at 180 °C for 8 h. After the reaction is completed, take out the product and dry it thoroughly in an 80 °C forced-air drying oven to remove the residual solvent in the product, and obtain the (ZrTaTi)C precursor.

[0073] Step 5: Wrap the (ZrTaTi)C precursor obtained in Step 4 with graphite paper, place it in a graphite crucible, and place the graphite crucible in a heat treatment furnace. React at 2100℃ for 2 hours under inert gas protection to obtain (ZrTaTi)C ultra-high temperature solid solution ceramic.

[0074] from Figure 1 As can be seen, a single-phase (ZrTaTi)C ultra-high temperature solid solution ceramic was prepared by using phenolic resin as a carbon source and heat treatment at 2100℃, and its crystallinity was better. From Figure 2 As can be seen in (d), after heat treatment at 2100℃, smaller nanocrystals precipitated from the large solid solution particles.

[0075] Comparative Example 5:

[0076] Step 1: Mix TaCl5 and C in a molar ratio of 1:1:1. 12 H 28O4Zr and C 16 H 36 O4Ti was dissolved in 50 mL of anhydrous ethanol. The mixture was then placed in an ultrasonic device to be fully dispersed until completely dissolved, forming a uniform white emulsion.

[0077] Step 2: Weigh a certain amount of phenolic resin (C6H6O)n·(CH2O)n according to the molar ratio of TaCl5 and phenolic resin of 1:1, and disperse it in 10mL of anhydrous ethanol. Sonicate the mixture for 30min until it is completely dissolved, forming a homogeneous orange-yellow solution.

[0078] Step 3: Add the phenolic resin solution obtained in Step 2 to the homogeneous emulsion obtained in Step 1. The solution turns orange-yellow instantly. Disperse the solution in an ultrasonic device for 30 minutes to form a homogeneous solution.

[0079] Step 4: Transfer the homogeneous solution obtained in Step 3 to a 100 mL reaction vessel for solvothermal reaction at 160 °C for 8 h. After the reaction is completed, take out the product and dry it thoroughly in an 80 °C forced-air drying oven to remove the residual solvent in the product, and obtain the (ZrTaTi)C precursor.

[0080] Step 5: Wrap the (ZrTaTi)C precursor obtained in Step 4 with graphite paper and place it in a graphite crucible. Place the graphite crucible in a heat treatment furnace and react at 1700℃ for 2 hours under inert gas protection. No complete solid solution occurs between the ZrC, TaC and TiC phases, and the product is a multiphase ultra-high temperature ceramic carbide.

[0081] from Figure 1 As can be seen, even after heat treatment at 1700℃ using phenolic resin as the carbon source, some ZrC phases still did not completely dissolve, indicating that single-phase (ZrTaTi)C ultra-high temperature solid solution ceramics cannot be obtained after heat treatment at 1700℃. Figure 2 As can be seen in (b), after heat treatment at 1700℃, the solid solution particles are unevenly distributed due to the incomplete solid solution reaction.

[0082] Comparative Example 6:

[0083] Step 1: Mix TaCl5 and C in a molar ratio of 1:1:1. 12 H 28 O4Zr and C 16 H 36 O4Ti was dissolved in 50 mL of anhydrous ethanol. The mixture was then placed in an ultrasonic device to be fully dispersed until completely dissolved, forming a uniform white emulsion.

[0084] Step 2: Weigh a certain amount of phenolic resin (C6H6O)n·(CH2O)n according to the molar ratio of TaCl5 and phenolic resin of 1:1, and disperse it in 10mL of anhydrous ethanol. Sonicate the mixture for 30min until it is completely dissolved, forming a homogeneous orange-yellow solution.

[0085] Step 3: Add the phenolic resin solution obtained in Step 2 to the homogeneous emulsion obtained in Step 1. The solution turns orange-yellow instantly. Disperse the solution in an ultrasonic device for 30 minutes to form a homogeneous solution.

[0086] Step 4: Place the homogeneous solution obtained in Step 3 in an oven at 160℃ and react for 8 hours. After the reaction is complete, take out the product and dry it thoroughly in a forced-air drying oven at 80℃ to remove the residual solvent in the product and obtain the (ZrTaTi)C precursor.

[0087] Step 5: The (ZrTaTi)C precursor obtained in Step 4 was wrapped in graphite paper and placed in a graphite crucible. The graphite crucible was then placed in a heat treatment furnace and reacted at 1900℃ for 2 hours under inert gas protection to finally obtain (ZrTaTiC) ultra-high temperature solid solution ceramics with a particle size greater than 20 μm. Figure 4 It can be seen that the (ZrTaTi)C ultra-high temperature solid solution ceramics prepared directly by the polymer conversion ceramic method without solvothermal reaction also have relatively large particle sizes, making it impossible to effectively control the microstructure and particle size of the final product. These results indicate that combining the solvothermal method and the polymer conversion ceramic method is beneficial for preparing (ZrTaTi)C ultra-high temperature solid solution ceramics with a narrow particle size distribution and nanoscale dimensions.

[0088] In the preparation of (ZrTaTi)C ultra-high temperature solid solution ceramics, the solvothermal reaction and heat treatment temperature significantly affect the microstructure and phase composition of single-phase (ZrTaTi)C ultra-high temperature solid solution ceramics. When precursor powder obtained by directly reacting the precursor and carbon source mixture at 160℃ for 8 hours without solvothermal reaction, followed by heat treatment at 1900℃, although single-phase ultra-high temperature solid solution ceramics can be formed, the product particle size is in the micrometer range. When the reaction temperature is lower (≤1700℃), the carbides have not yet fully dissolved, ultimately forming multiphase ultra-high temperature carbide ceramics.

[0089] Example 7

[0090] Step 1: Mix TaCl5 and C in a molar ratio of 1:1:1. 12 H 28 O4Zr and C 16 H 36O4Ti was dissolved in 50 mL of anhydrous ethanol. The mixture was then placed in an ultrasonic device to be fully dispersed until completely dissolved, forming a uniform white emulsion.

[0091] Step 2: Weigh a certain amount of phenolic resin (C6H6O)n·(CH2O)n according to the molar ratio of TaCl5 to phenolic resin of 1.5:1, and disperse it in 10 mL of anhydrous ethanol. Sonicate the mixture for 40 min until it is completely dissolved, forming a homogeneous orange-yellow solution.

[0092] Step 3: Add the phenolic resin solution obtained in Step 2 to the homogeneous emulsion obtained in Step 1. The solution turns orange-yellow instantly. Disperse the solution in an ultrasonic device for 40 minutes to form a homogeneous solution.

[0093] Step 4: Transfer the homogeneous solution obtained in Step 3 to a 100 mL reaction vessel for solvothermal reaction at 140 °C for 10 h. After the reaction is completed, take out the product and dry it thoroughly in an 80 °C forced-air drying oven to remove the residual solvent in the product, and obtain the (ZrTaTi)C precursor.

[0094] Step 5: Wrap the (ZrTaTi)C precursor obtained in Step 4 with graphite paper, place it in a graphite crucible, and place the graphite crucible in a heat treatment furnace. React at 2000℃ for 2 hours under inert gas protection to obtain (ZrTaTi)C ultra-high temperature solid solution ceramic.

[0095] Example 8

[0096] Step 1: Mix TaCl5 and C in a molar ratio of 1:1:1. 12 H 28 O4Zr and C 16 H 36 O4Ti was dissolved in 50 mL of anhydrous ethanol. The mixture was then placed in an ultrasonic device to be fully dispersed until completely dissolved, forming a uniform white emulsion.

[0097] Step 2: Weigh a certain amount of phenolic resin (C6H6O)n·(CH2O)n according to the molar ratio of TaCl5 to phenolic resin of 1.5:1, disperse it in 10mL of anhydrous ethanol, and sonicate for 60min until completely dissolved to form an orange-yellow homogeneous solution.

[0098] Step 3: Add the phenolic resin solution obtained in Step 2 to the homogeneous emulsion obtained in Step 1. The solution turns orange-yellow instantly. Disperse the solution in an ultrasonic device for 60 minutes to form a homogeneous solution.

[0099] Step 4: Transfer the homogeneous solution obtained in Step 3 to a 100 mL reaction vessel for solvothermal reaction at 150 °C for 6 h. After the reaction is completed, take out the product and dry it thoroughly in an 80 °C forced-air drying oven to remove the residual solvent in the product, and obtain the (ZrTaTi)C precursor.

[0100] Step 5: Wrap the (ZrTaTi)C precursor obtained in Step 4 with graphite paper, place it in a graphite crucible, and place the graphite crucible in a heat treatment furnace. React at 2100℃ for 2 hours under inert gas protection to obtain (ZrTaTi)C ultra-high temperature solid solution ceramic.

[0101] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for synthesizing (ZrTaTi)C ultra-high temperature solid solution ceramics via a solvothermal polymer conversion ceramic method, characterized in that, Includes the following steps: Step 1: Tantalum pentachloride, zirconium propoxide, and tetrabutyl titanate are dissolved in anhydrous ethanol and ultrasonically dispersed to form a precursor solution containing a transition metal source; in Step 1, the atomic molar ratio of tantalum, zirconium, and titanium in tantalum pentachloride, zirconium propoxide, and tetrabutyl titanate is 1:1:

1. Step 2: Dissolve the resin in anhydrous ethanol to form a carbon source solution; Step 3: Mix the precursor solution containing the transition metal source and the carbon source solution, and disperse them by ultrasonication to form a reaction solution; Step 4: Place the reaction solution in a reaction vessel for a solvothermal reaction. After the reaction is completed, dry the reaction product to obtain the (ZrTaTi)C ceramic precursor. Step 5: Wrap the (ZrTaTi)C ceramic precursor in graphite paper, place it in a graphite crucible, and then place the graphite crucible in a heat treatment furnace. After reacting under an inert atmosphere, (ZrTaTi)C solid solution ceramic is obtained. The heat treatment reaction temperature is 1900-2100℃, and the heat treatment time is 2 h. (ZrTaTi)C ultra-high temperature solid solution ceramics are granular, including nearly spherical (ZrTaTi)C ultra-high temperature ceramic solid solution particles, which are encapsulated by a carbon layer.

2. The method for synthesizing (ZrTaTi)C ultra-high temperature solid solution ceramics by a solvothermal polymer conversion ceramic method according to claim 1, characterized in that, In step 2, the resin is phenolic resin or epoxy resin.

3. The method for synthesizing (ZrTaTi)C ultra-high temperature solid solution ceramics by a solvothermal polymer conversion ceramic method according to claim 2, characterized in that, In step 2, the amount of phenolic resin added is prepared according to the molar ratio of TaCl5 to phenolic resin of 1:1 to 2:

1.

4. The method for synthesizing (ZrTaTi)C ultra-high temperature solid solution ceramics by a solvothermal polymer conversion ceramic method according to claim 1, characterized in that, In step 3, the ultrasonic dispersion time is 30-60 min.

5. The method for synthesizing (ZrTaTi)C ultra-high temperature solid solution ceramics by a solvothermal polymer conversion ceramic method according to claim 1, characterized in that, In step 4, the solvothermal reaction temperature is 140-180 ℃, and the solvothermal reaction time is 6-10 h.

6. A (ZrTaTi)C ultra-high temperature solid solution ceramic prepared by any one of claims 1-5, characterized in that, (ZrTaTi)C ultra-high temperature solid solution ceramics are granular, including nearly spherical (ZrTaTi)C ultra-high temperature ceramic solid solution particles, which are encapsulated by a carbon layer.

7. The (ZrTaTi)C ultra-high temperature solid solution ceramic according to claim 6, characterized in that, The average diameter of the granular ultra-high temperature solid solution ceramic particles is 500 nm.

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