Preparation method capable of preparing high-purity ZrC powder on large scale and ZrC powder

Abstract

The invention provides a preparation method capable of preparing high-purity ZrC powder on a large scale and ZrC powder.The preparation method comprises the steps that firstly, zirconium metal salt, deionized water, organic ligands and absolute ethyl alcohol are subjected to ultrasonic mixing, and a metal salt solution and an organic solution are obtained; pouring the organic solution into the metal salt solution to form a mixed solution, and ultrasonically removing gas in the solution; dropwise adding a small amount of ammonia water into the mixed solution, shaking, performing ultrasonic treatment to enable the solution to be uniform, and standing for a period of time to obtain metal organic gel; centrifugally cleaning the gel, and drying the cleaned gel in a drying oven at a certain temperature to obtain dry gel powder; and finally, putting the dry gel powder into a graphite crucible, and carrying out high-temperature cracking in a vacuum carbon tube furnace to obtain the high-purity ZrC powder. Impurities are prevented from being introduced into a traditional ball milling process, the metal organic gel can achieve uniform combination of metal ions and organic ligand atoms, the ZrC powder is endowed with the excellent characteristics of 50-200 nm nanoscale size, high purity, uniform distribution, spherical morphology and the like, and meanwhile the preparation method is short in period, low in temperature, low in cost, environmentally friendly in raw material and suitable for industrial production. The method is easy to control and suitable for large-scale preparation.

Description

Technical Field

[0001] The present invention relates to the technical field of material chemistry, and specifically to a preparation method for large-scale preparation of high-purity ZrC powder and ZrC powder. Background Art

[0002] ZrC ceramic is an ultra-high temperature material with the advantages of high melting point, high hardness and good thermal conductivity. It has excellent high temperature chemical stability and ablation resistance at high temperature. Compared with HfC and TaC, which are also ultra-high temperature carbide materials, ZrC has low cost, simple preparation technology and low equipment requirements. It can be used in launcher shell coatings, nuclear fuel particle coatings, and ultra-high temperature materials, and has broad application prospects in the aerospace field.

[0003] The existing methods for preparing ZrC powder include carbothermal reduction, sol-gel, high-energy ball milling and self-propagating high-temperature synthesis. Carbothermal reduction is the most widely used method for preparing ZrC. It is inexpensive, simple in process and suitable for large-scale production. However, the high preparation temperature leads to coarsening of particles, and it is difficult to avoid the introduction of impurities during mixing. Existing literature shows (OBRADOVIĆ N, FENG L, FILIPOVIĆ S, et al. Effect of mechanical activation on carbothermal synthesis and densification of ZrC [J]. Journal of theEuropean Ceramic Society, 2023, 43(16): 7306-13.) that a mixture of ZrO2 and C is obtained by high-energy ball milling, and ZrC is prepared by carbothermal reduction. The grinding time is 0-120 minutes. The powder obtained at a synthesis temperature of 1600°C has a significant carbon content. As the ball milling time increases, ZrO2 appears in the powder, and the size of the ZrC particles is also larger (3.9-5.4μm). This method is difficult to meet the requirements for preparing high-purity nano ZrC powder.

[0004] Therefore, those skilled in the art urgently need to provide a preparation method and ZrC powder that can be used to prepare high-purity ZrC powder on a large scale, avoid the introduction of impurities by the traditional ball milling process, use metal organic gel as a precursor, and achieve uniform atomic-scale bonding of metal ions and organic ligands through metal organic gel. The prepared ZrC powder has high purity, a nanoscale size of 50-200nm, and is uniformly distributed. The preparation method has a short cycle, low temperature, and low cost, and is suitable for large-scale preparation. Summary of the invention

[0005] The purpose of the present invention is to provide a preparation method and ZrC powder capable of preparing high-purity ZrC powder on a large scale, avoiding the introduction of impurities by a traditional ball milling process, using a metal organic gel as a precursor, and realizing uniform atomic-scale combination of metal ions and organic ligands through the metal organic gel. The prepared ZrC powder has high purity, a nanometer size of 50-200nm, and uniform distribution, and the preparation method has a short cycle, a low temperature, and a low cost, and is suitable for large-scale preparation.

[0006] The present invention provides a preparation method for large-scale preparation of high-purity ZrC powder and ZrC powder, comprising the following steps: S1. Mixing zirconium metal salt with deionized water, ultrasonicating and stirring with a water bath ultrasonic device until completely dissolved, to obtain a metal salt solution; S2, mixing the organic ligand with ethanol, performing ultrasound and stirring until the organic ligand is completely dissolved to obtain an organic solution; S3, mixing the metal salt solution obtained in step S1 with the organic solution obtained in step S2, performing ultrasound treatment until no bubbles are generated in the solution to obtain a metal organic sol, and allowing the mixture to stand for a preset time; S4, adding a preset amount of ammonia water to the metal organic sol obtained in step S3, shaking and ultrasonicating until the sol is evenly mixed, and standing for a preset time to obtain a metal organic gel; S5, placing the metal organic gel obtained in step S4 in a high temperature oven for drying until a dry metal organic gel is obtained; S6, washing the dried metal organic gel obtained in step S5 by centrifugation in a centrifuge, and drying the washed gel in a high-temperature oven until a pure dry gel powder is obtained; S7, placing the dry gel powder obtained in step S6 in a graphite crucible, and pyrolyzing it in a vacuum carbon tube furnace to finally obtain high-purity ZrC powder.

[0007] Preferably, in step S1, the zirconium metal salt is ZrCl4; the total amount of the zirconium metal salt added is 1-60 mmol; the amount of deionized water added is 2-120 ml; the frequency of ultrasound performed using a water bath ultrasound device is 40 kHz, and the temperature of ultrasound is 20-30°C.

[0008] Preferably, in step S2, the organic ligand is pyromellitic acid; the amount of the organic ligand added is 1-60 mmol; and the amount of the ethanol added is 2-120 ml.

[0009] Preferably, in step S3, the organic solution is poured into the metal salt solution for mixing; after obtaining the metal organic sol, the solution is allowed to stand for 1 to 48 hours.

[0010] Preferably, in step S4, the amount of ammonia water added is 50-30000ul; and the standing time is 1-48h.

[0011] Preferably, in step S5, the drying temperature in the high temperature oven is 120° C. and the drying time is 12 to 24 hours.

[0012] Preferably, in step S6, the rotation speed of the centrifuge is 8000 rpm, the centrifugal cleaning time is 5 min, and the centrifugal cleaning is performed 3 times.

[0013] Preferably, in step S6, the drying temperature in the high temperature oven is 120° C. and the drying time is 12 to 24 hours.

[0014] Preferably, in step S7, the cracking process is: the heating rate of the vacuum carbon tube furnace is 5~20℃ / min, first keeping warm in an environment of 800℃ for 1~6 hours, and then keeping warm in an environment of 1400~1700℃ for 1~3 hours; at the same time, cracking is carried out in a negative pressure argon environment, the flow rate of the argon gas is 100~300 sccm, and the negative pressure environment is less than 100 Pa.

[0015] The present invention also provides a ZrC powder, which is processed by the above-mentioned preparation method capable of preparing high-purity ZrC powder on a large scale.

[0016] The present invention provides a preparation method and ZrC powder capable of preparing high-purity ZrC powder on a large scale, which has the following advantages: 1. The present invention uses zirconium chloride as the metal source and pyromellitic acid as the organic ligand, which has lower cost than other organic metal compounds; 2. The present invention increases the pH of the sol by adding ammonia water to promote the transition from sol to gel, and can react with chloride ions in the sol to generate ammonium chloride, thereby removing chloride ion impurities in the sol. The ammonium chloride can be removed by washing with water, thereby improving the purity of the ZrC nanopowder after pyrolysis; 3. The present invention uses metal organic gel as a precursor, which can achieve uniform atomic-scale bonding of metal ions and organic ligands, effectively reducing the preparation temperature of ZrC after pyrolysis, and can obtain ZrC nanopowders with uniform morphology and size distribution, and the obtained powders have high purity; 4. The present invention avoids the ball milling process and effectively reduces the chance of impurities being introduced. At the same time, the preparation method of the present invention has a short preparation cycle, a low temperature, a low cost, is easy to control, and is suitable for large-scale preparation. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 The data diagram is a Fourier transform infrared spectroscopy analysis data of the metal organic xerogel powder and pyromellitic acid (PMA) in Examples 1 to 3; Figure 2 The data diagram of X-ray diffractometer analysis of ZrC nanopowder prepared in Examples 1 to 4; Figure 3 The microscopic morphology of the ZrC nanopowder prepared in Example 3 was scanned by a scanning electron microscope; Figure 4 This is a high-resolution image of the ZrC nanopowder prepared in Example 2 taken by a transmission electron microscope; Figure 5 The energy spectrum analysis diagram of Zr and C in the ZrC nanopowder prepared in Example 5; Figure 6 This is a photo of the metal organic gel prepared in Example 6. DETAILED DESCRIPTION

[0018] The present invention can be better understood according to the following examples. However, it is easy for those skilled in the art to understand that the contents described in the examples are only used to illustrate the present invention, and should not and will not limit the present invention described in detail in the claims.

[0019] The experimental methods described in the following examples are conventional methods unless otherwise specified; the reagents and materials described are commercially available unless otherwise specified.

[0020] The present invention provides a preparation method for large-scale preparation of high-purity ZrC powder and ZrC powder, comprising the following steps: S1. Mix the zirconium metal salt with deionized water, and use a water bath ultrasonic device to perform ultrasonication and stirring until the mixture is completely dissolved to obtain a metal salt solution.

[0021] Specifically, in step S1, the zirconium metal salt is ZrCl4; the total amount of zirconium metal salt added is 1-60 mmol; the amount of deionized water added is 2-120 ml; the frequency of the ultrasonic wave performed by the water bath ultrasonic equipment is 40 kHz, and the temperature of the ultrasonic wave is 20-30°C.

[0022] The invention uses chloride salt of zirconium metal as a metal source and pyromellitic acid as an organic ligand, and has lower cost than other organic metal compounds.

[0023] S2. Mix the organic ligand with ethanol, perform ultrasound and stirring until it is completely dissolved to obtain an organic solution.

[0024] Specifically, in step S2, the organic ligand is pyromellitic acid; the amount of the organic ligand added is 1-60 mmol; and the amount of ethanol added is 2-120 ml.

[0025] S3, mixing the metal salt solution obtained in step S1 with the organic solution obtained in step S2, performing ultrasonic treatment until no bubbles are generated in the solution to obtain a metal organic sol, and allowing the mixture to stand for a preset time.

[0026] Specifically, in step S3, the organic solution is poured into the metal salt solution for mixing; after obtaining the metal organic sol, the solution is allowed to stand for 1 to 48 hours.

[0027] S4, adding a preset amount of ammonia water to the metal organic sol obtained in step S3, shaking and ultrasonicating until the sol is evenly mixed, and leaving it to stand for a preset time to obtain the metal organic gel.

[0028] Specifically, in step S4, the amount of ammonia water added is 50-30000 μl; and the standing time is 1-48 hours.

[0029] The present invention increases the pH of the sol by adding ammonia water to promote the transition from sol to gel, and can react with chloride ions in the sol to generate ammonium chloride, thereby removing chloride ion impurities in the sol. The ammonium chloride can be removed by washing with water, thereby improving the purity of the ZrC nanopowder after pyrolysis.

[0030] S5, placing the metal organic gel obtained in step S4 in a high temperature oven for drying until a dry metal organic gel is obtained.

[0031] Specifically, in step S5, the temperature of the high temperature oven is 120° C. and the drying time is 12 to 24 hours.

[0032] S6. The dried metal organic gel obtained in step S5 is centrifuged and cleaned in a centrifuge, and the cleaned gel is placed in a high-temperature oven for drying until a pure dry gel powder is obtained.

[0033] Specifically, in step S6, the speed of the centrifuge is 8000 rpm, the centrifugal cleaning time is 5 minutes, and the centrifugal cleaning is performed 3 times. The drying temperature in the high-temperature oven is 120° C., and the time is 12 to 24 hours.

[0034] The present invention uses metal organic gel as a precursor, and can realize the uniform combination of metal ions and organic ligands at the atomic scale through the metal organic gel, effectively reducing the preparation temperature of ZrC after pyrolysis, and can obtain ZrC nanopowder with uniform morphology and size distribution, and the obtained powder has high purity; S7, placing the dry gel powder obtained in step S6 in a graphite crucible, and pyrolyzing it in a vacuum carbon tube furnace to finally obtain high-purity ZrC powder.

[0035] Specifically, in step S7, the cracking process is as follows: the temperature rise rate of the vacuum carbon tube furnace is 5-20°C / min, firstly, the temperature is kept at 800°C for 1-6 hours, and then at 1400-1700°C for 1-3 hours. At the same time, the cracking is carried out in a negative pressure argon environment, the flow rate of the argon gas is 100-300 sccm, and the negative pressure environment is less than 100 Pa.

[0036] Example 1 The present invention provides a preparation method for large-scale preparation of high-purity ZrC powder and ZrC powder, comprising the following steps: S1. Mix 1 mmol of ZrCl4 with 2 ml of H2O, and perform ultrasonication at a frequency of 40 kHz at 25°C using a water bath ultrasonic device and stir until the mixture is completely dissolved to obtain a metal salt solution; S2, mixing 1 mmol of pyromellitic acid with 2 ml of ethanol, ultrasonicating at a frequency of 40 kHz at 25° C. and stirring until completely dissolved to obtain an organic solution; S3, pouring the organic solution obtained in step S2 into the metal salt solution obtained in step S1, performing ultrasound at a frequency of 40 kHz at 25° C. until no bubbles are generated in the solution to obtain a metal organic sol, and standing for 1 hour; S4, adding 500 μl of ammonia water to the metal organic sol obtained in step S3, immediately shaking and ultrasonicating until the sol is evenly mixed, and leaving it to stand for 2 hours to obtain the metal organic gel; S5, placing the metal organic gel obtained in step S4 in a high temperature oven for drying until a dry metal organic gel is obtained; the drying temperature in the high temperature oven is 120° C. and the drying time is 18 hours; S6, washing the metal organic gel obtained in step S5 in a centrifuge, the speed of the centrifuge is 8000 rpm, the washing time is 5 min, and the washing is repeated 3 times; and the washed gel is placed in a high temperature oven for drying until a pure dry gel powder is obtained; the drying temperature in the high temperature oven is 120° C., and the drying time is 18 h; S7. The dry gel powder obtained in step S6 is placed in a graphite crucible and pyrolyzed in a vacuum carbon tube furnace to finally obtain high-purity ZrC powder; the pyrolysis process is as follows: the heating rate of the vacuum carbon tube furnace is 10°C / min, firstly kept in an environment of 800°C for 3 h, and then kept in an environment of 1500°C for 1 h; at the same time, the pyrolysis is carried out in a negative pressure argon environment, the flow rate of the argon is 100sccm, and the negative pressure environment is less than 100 Pa.

[0037] Example 2 This embodiment provides a preparation method and ZrC powder capable of preparing high-purity ZrC powder on a large scale, comprising the following steps: S1. Mix 1.5 mmol of ZrCl4 with 2 ml of H2O, and use a water bath ultrasonic device to ultrasonicate at a frequency of 40 kHz at 25°C and stir until completely dissolved to obtain a metal salt solution.

[0038] S2. Mix 1 mmol of pyromellitic acid with 2 ml of ethanol, perform ultrasound at a frequency of 40 kHz at 25° C. and stir until the mixture is completely dissolved to obtain an organic solution.

[0039] S3, mixing the metal salt solution obtained in step S1 with the organic solution obtained in step S2, and performing ultrasonic treatment until no bubbles are generated in the solution to obtain a metal organic sol, and allowing the mixture to stand for 2 hours.

[0040] S4. Add 500 μl of ammonia water to the metal organic sol obtained in step S3, shake and perform ultrasound until the sol is evenly mixed, and let it stand for 2 hours to obtain the metal organic gel.

[0041] S5, placing the metal organic gel obtained in step S4 in a high temperature oven for drying until a dry metal organic gel is obtained; the drying temperature in the high temperature oven is 120° C. and the drying time is 18 hours; S6, washing the metal organic gel obtained in step S5 in a centrifuge, the speed of the centrifuge is 8000 rpm, the washing time is 5 min, and the washing is repeated 3 times; and the washed gel is placed in a high temperature oven for drying until a pure dry gel powder is obtained; the drying temperature in the high temperature oven is 120° C., and the drying time is 18 h; S7. The dry gel powder obtained in step S6 is placed in a graphite crucible and pyrolyzed in a vacuum carbon tube furnace to finally obtain high-purity ZrC powder; the pyrolysis process is as follows: the heating rate of the vacuum carbon tube furnace is 10°C / min, firstly kept in an environment of 800°C for 3 h, and then kept in an environment of 1500°C for 1 h; at the same time, the pyrolysis is carried out in a negative pressure argon environment, the flow rate of the argon is 100sccm, and the negative pressure environment is less than 100 Pa.

[0042] Example 3 This embodiment provides a preparation method and ZrC powder capable of preparing high-purity ZrC powder on a large scale, comprising the following steps: S1. Mix 2 mmol of ZrCl4 with 2 ml of H2O, and perform ultrasonication at a frequency of 40 kHz at 25°C using a water bath ultrasonic device and stir until the mixture is completely dissolved to obtain a metal salt solution.

[0043] S2. Mix 1 mmol of pyromellitic acid with 2 ml of ethanol, perform ultrasound at a frequency of 40 kHz at 25° C. and stir until the mixture is completely dissolved to obtain an organic solution.

[0044] S3, mixing the metal salt solution obtained in step S1 with the organic solution obtained in step S2, and subjecting the mixture to ultrasonic treatment until no bubbles are generated in the solution to obtain a metal organic sol, and allowing the mixture to stand for 2 hours.

[0045] S4. Add 500 μl of ammonia water to the metal organic sol obtained in step S3, shake and perform ultrasound until the sol is evenly mixed, and let it stand for 2 hours to obtain the metal organic gel.

[0046] S5, placing the metal organic gel obtained in step S4 in a high temperature oven for drying until a dry metal organic gel is obtained; the drying temperature in the high temperature oven is 120° C. and the drying time is 18 hours; S6, washing the metal organic gel obtained in step S5 in a centrifuge, the speed of the centrifuge is 8000 rpm, the washing time is 5 min, and the washing is repeated 3 times; and the washed gel is placed in a high temperature oven for drying until a pure dry gel powder is obtained; the drying temperature in the high temperature oven is 120° C., and the drying time is 18 h; S7. The dry gel powder obtained in step S6 is placed in a graphite crucible and pyrolyzed in a vacuum carbon tube furnace to finally obtain high-purity ZrC powder; the pyrolysis process is as follows: the heating rate of the vacuum carbon tube furnace is 10°C / min, firstly kept in an environment of 800°C for 3 h, and then kept in an environment of 1500°C for 1 h; at the same time, the pyrolysis is carried out in a negative pressure argon environment, the flow rate of the argon is 100sccm, and the negative pressure environment is less than 100 Pa.

[0047] Example 4 This embodiment provides a preparation method and ZrC powder capable of preparing high-purity ZrC powder on a large scale, comprising the following steps: S1. Mix 2.5 mmol of ZrCl4 with 2 ml of H2O, and use a water bath ultrasonic device to ultrasonicate at a frequency of 40 kHz at 25°C and stir until completely dissolved to obtain a metal salt solution.

[0048] S2. Mix 1 mmol of pyromellitic acid with 2 ml of ethanol, perform ultrasound at a frequency of 40 kHz at 25° C. and stir until the mixture is completely dissolved to obtain an organic solution.

[0049] S3, mixing the metal salt solution obtained in step S1 with the organic solution obtained in step S2, and subjecting the mixture to ultrasonic treatment until no bubbles are generated in the solution to obtain a metal organic sol, and allowing the mixture to stand for 2 hours.

[0050] S4. Add 500 μl of ammonia water to the metal organic sol obtained in step S3, shake and perform ultrasound until the sol is evenly mixed, and let it stand for 2 hours to obtain the metal organic gel.

[0051] S5, placing the metal organic gel obtained in step S4 in a high temperature oven for drying until a dry metal organic gel is obtained; the drying temperature in the high temperature oven is 120° C. and the drying time is 18 hours; S6, washing the metal organic gel obtained in step S5 in a centrifuge, the speed of the centrifuge is 8000 rpm, the washing time is 5 min, and the washing is repeated 3 times; and the washed gel is placed in a high temperature oven for drying until a pure dry gel powder is obtained; the drying temperature in the high temperature oven is 120° C., and the drying time is 18 h; S7. The dry gel powder obtained in step S6 is placed in a graphite crucible and pyrolyzed in a vacuum carbon tube furnace to finally obtain high-purity ZrC powder; the pyrolysis process is as follows: the heating rate of the vacuum carbon tube furnace is 5°C / min, firstly kept at 800°C for 3 h, and then kept at 1500°C for 1 h; at the same time, the pyrolysis is carried out in a negative pressure argon environment, the flow rate of the argon is 100sccm, and the negative pressure environment is less than 100 Pa.

[0052] Example 5 This embodiment provides a preparation method and ZrC powder capable of preparing high-purity ZrC powder on a large scale, comprising the following steps: S1. Mix 60 mmol of ZrCl4 with 60 ml of H2O, perform ultrasonication at a frequency of 40 kHz at 30°C using a water bath ultrasonic device and stir until the mixture is completely dissolved to obtain a metal salt solution.

[0053] S2. 30 mmol of pyromellitic acid was mixed with 60 ml of ethanol, and ultrasonicated at a frequency of 40 kHz at 30° C. and stirred until completely dissolved to obtain an organic solution.

[0054] S3, mixing the metal salt solution obtained in step S1 with the organic solution obtained in step S2, and performing ultrasonic treatment until no bubbles are generated in the solution to obtain a metal organic sol, and allowing the mixture to stand for 24 hours.

[0055] S4. Add 15000 μl of ammonia water to the metal organic sol obtained in step S3, shake and perform ultrasound until the sol is evenly mixed, and let it stand for 24 hours to obtain the metal organic gel.

[0056] S5, placing the metal organic gel obtained in step S4 in a high temperature oven for drying until a dry metal organic gel is obtained; the drying temperature in the high temperature oven is 120° C. and the drying time is 24 hours; S6. The metal organic gel obtained in step S5 is centrifuged and washed in a centrifuge at a speed of 8000 rpm for 5 minutes and washed three times; and the washed gel is placed in a high-temperature oven for drying until a pure dry gel powder is obtained; the drying temperature in the high-temperature oven is 120° C. for 24 hours.

[0057] S7. The dry gel powder obtained in step S6 is placed in a graphite crucible and pyrolyzed in a vacuum carbon tube furnace to finally obtain high-purity ZrC powder; the pyrolysis process is as follows: the heating rate of the vacuum carbon tube furnace is 15°C / min, firstly kept in an environment of 800°C for 6 hours, and then kept in an environment of 1700°C for 3 hours; at the same time, the pyrolysis is carried out in a negative pressure argon environment, the flow rate of the argon is 300sccm, and the negative pressure environment is less than 100 Pa.

[0058] Example 6 This embodiment provides a preparation method and ZrC powder capable of preparing high-purity ZrC powder on a large scale, comprising the following steps: S1. Mix 60 mmol of ZrCl4 with 120 ml of H2O, perform ultrasound at a frequency of 40 kHz at 20°C using a water bath ultrasound device and stir until the mixture is completely dissolved to obtain a metal salt solution.

[0059] S2. 60 mmol of pyromellitic acid was mixed with 120 ml of ethanol, and ultrasonicated at a frequency of 40 kHz at 20° C. and stirred until completely dissolved to obtain an organic solution.

[0060] S3, mixing the metal salt solution obtained in step S1 with the organic solution obtained in step S2, and subjecting the mixture to ultrasonic treatment until no bubbles are generated in the solution to obtain a metal organic sol, and allowing the mixture to stand for 48 hours.

[0061] S4. Add 30000 μl of ammonia water to the metal organic sol obtained in step S3, shake and perform ultrasound until the sol is evenly mixed, and let it stand for 48 hours to obtain the metal organic gel.

[0062] S5, placing the metal organic gel obtained in step S4 in a high temperature oven for drying until a dry metal organic gel is obtained; the drying temperature in the high temperature oven is 120° C. and the drying time is 24 hours; S6. The metal organic gel obtained in step S5 is centrifuged and washed in a centrifuge at a speed of 8000 rpm for 5 minutes and washed three times; and the washed gel is placed in a high-temperature oven for drying until a pure dry gel powder is obtained; the drying temperature in the high-temperature oven is 120° C. for 24 hours.

[0063] S7. The dry gel powder obtained in step S6 is placed in a graphite crucible and pyrolyzed in a vacuum carbon tube furnace to finally obtain high-purity ZrC powder; the pyrolysis process is as follows: the heating rate of the vacuum carbon tube furnace is 5°C / min, firstly kept at 800°C for 6 hours, and then kept at 1700°C for 3 hours; at the same time, the pyrolysis is carried out in a negative pressure argon environment, the flow rate of the argon is 300sccm, and the negative pressure environment is less than 100 Pa.

[0064] Example 7 This embodiment provides a preparation method and ZrC powder capable of preparing high-purity ZrC powder on a large scale, comprising the following steps: S1. Mix 2 mmol of ZrCl4 with 2 ml of H2O, perform ultrasound at a frequency of 40 kHz at 20°C using a water bath ultrasound device and stir until the mixture is completely dissolved to obtain a metal salt solution.

[0065] S2. Mix 1 mmol of pyromellitic acid with 2 ml of ethanol, perform ultrasound at a frequency of 40 kHz at 20° C. and stir until the mixture is completely dissolved to obtain an organic solution.

[0066] S3, mixing the metal salt solution obtained in step S1 with the organic solution obtained in step S2, and performing ultrasonic treatment until no bubbles are generated in the solution to obtain a metal organic sol, and allowing to stand for 1 hour.

[0067] S4. Add 50 μl of ammonia water to the metal organic sol obtained in step S3, shake and perform ultrasound until the sol is evenly mixed, and let it stand for 1 hour to obtain the metal organic gel.

[0068] S5, placing the metal organic gel obtained in step S4 in a high temperature oven for drying until a dry metal organic gel is obtained; the drying temperature in the high temperature oven is 120° C. and the drying time is 12 hours; S6. The metal organic gel obtained in step S5 is centrifuged and washed in a centrifuge at a speed of 8000 rpm for 5 minutes and washed three times; and the washed gel is placed in a high-temperature oven for drying until a pure dry gel powder is obtained; the drying temperature in the high-temperature oven is 120° C. for 12 hours.

[0069] S7. The dry gel powder obtained in step S6 is placed in a graphite crucible and pyrolyzed in a vacuum carbon tube furnace to finally obtain high-purity ZrC powder; the pyrolysis process is as follows: the heating rate of the vacuum carbon tube furnace is 20°C / min, firstly kept at 800°C for 1 h, and then kept at 1400°C for 1 h; at the same time, the pyrolysis is carried out in a negative pressure argon environment, the flow rate of the argon is 200sccm, and the negative pressure environment is less than 100 Pa.

[0070] Figure 1 The data graph of infrared spectrum analysis of metal organic xerogel powder in Examples 1 to 3. Among them, PMA shown in the figure is the Fourier infrared spectrum of pyromellitic acid; 1:1 is the Fourier infrared spectrum of metal organic xerogel powder prepared in Example 1; 1.5:1 is the Fourier infrared spectrum of metal organic xerogel powder prepared in Example 2; 2:1 is the Fourier infrared spectrum of metal organic xerogel powder prepared in Example 3. It can be seen from the figure that the Fourier infrared absorption spectra of metal organic xerogel powder in Examples 1, 2, and 3 are all at 620cm -1 and 1527cm -1 The Zr-O-Zr and Zr-OC absorption peaks are shown respectively, and at 1120 cm -1 and 768cm -1 All of them showed the characteristic absorption peak of CH of the benzene ring skeleton of PMA, indicating that a metal organic gel containing Zr ions and organic ligands was synthesized.

[0071] Figure 2 is the XRD of the ZrC nanopowder prepared in Examples 1 to 4. Among them, 1.5:1 shown in the figure is the XRD of the ZrC nanopowder prepared in Example 1; 1.5:1 is the XRD of the ZrC nanopowder prepared in Example 2; 2:1 is the XRD of the ZrC nanopowder prepared in Example 3; 2.5:1 is the XRD of the ZrC nanopowder prepared in Example 4. It can be seen from the data graph that the nanopowders prepared in Examples 1 to 3 show single-phase ZrC, and the medium-entropy ZrC nanopowder prepared in Example 4 contains a zirconium oxide phase, indicating that the carbon source in Example 4 is insufficient. .

[0072] Figure 3 This is a scanning electron microscope (SEM) microscopic morphology of the ZrC nanopowder prepared in Example 3. It can be seen from the figure that the obtained ZrC particles are small (50-150nm) and evenly distributed.

[0073] Figure 4 This is a high-resolution transmission electron microscope image (hereinafter referred to as HRTEM) of the ZrC nanopowder prepared in Example 2. The image shows that the stripe spacing with a periodic lattice structure is 0.2385 nm, which is basically consistent with the crystal plane spacing of the (200) plane of the ZrC standard card PDF#65-0973.

[0074] Figure 5 This is the energy spectrum analysis diagram of Zr and C in the ZrC nanopowder prepared in Example 5. The figure shows that the two elements Zr and C are uniformly dispersed at the nanoscale without segregation.

[0075] Figure 6This is the metal organic gel prepared in Example 6. As can be seen from the figure, the metal organic gel prepared on an enlarged scale is completely gelled and has good uniformity, indicating that this method is feasible for large-scale preparation of ZrC.

[0076] In summary, the present invention avoids the introduction of impurities by the traditional ball milling process. The metal organic gel (amorphous MOFs) can achieve uniform atomic-scale bonding of metal ions and organic ligands, giving the ZrC powder excellent properties such as 50-200nm nanoscale size, high purity, uniform distribution, and spherical morphology. At the same time, the preparation method described in the present invention has a short cycle, low temperature, low cost, environmentally friendly raw materials, easy control, and is suitable for large-scale preparation.

[0077] A person skilled in the art can make various modifications and applications without departing from the essential characteristics of the embodiments. For example, each component detailed in the embodiments can be modified and operated, and the differences related to the modifications and applications can be considered to be included in the scope of protection of the present invention defined by the appended claims.

[0078] The embodiments referred to in this specification mean that the specific features, structures or characteristics described in conjunction with the embodiments are included in at least one embodiment of the present invention. These terms appearing in various places in the specification do not necessarily refer to the same embodiment. In addition, when specific features, structures or characteristics are described in conjunction with any embodiment, it is considered that they fall within the scope of these specific features, structures or characteristics that can be implemented by a person of ordinary skill in the art in conjunction with other embodiments.

Claims

1. A method for preparing high-purity ZrC powder on a large scale and ZrC powder, characterized in that: The following steps are involved: S1. Mixing zirconium metal salt with deionized water, ultrasonicating and stirring with a water bath ultrasonic device until completely dissolved, to obtain a metal salt solution; S2, mixing the organic ligand with ethanol, performing ultrasound and stirring until the organic ligand is completely dissolved to obtain an organic solution; S3, mixing the metal salt solution obtained in step S1 with the organic solution obtained in step S2, performing ultrasound treatment until no bubbles are generated in the solution to obtain a metal organic sol, and allowing the mixture to stand for a preset time; S4, adding a preset amount of ammonia water to the metal organic sol obtained in step S3, shaking and ultrasonicating until the sol is evenly mixed, and standing for a preset time to obtain a metal organic gel; S5, placing the metal organic gel obtained in step S4 in a high temperature oven for drying until a dry metal organic gel is obtained; S6, washing the dried metal organic gel obtained in step S5 by centrifugation in a centrifuge, and drying the washed gel in a high-temperature oven until a pure dry gel powder is obtained; S7, placing the dry gel powder obtained in step S6 in a graphite crucible, and pyrolyzing it in a vacuum carbon tube furnace to finally obtain high-purity ZrC powder.

2. The method for preparing high-purity ZrC powder on a large scale according to claim 1, characterized in that: In the step S1, the zirconium metal salt is ZrCl4; the total amount of the zirconium metal salt added is 1-60 mmol; the amount of deionized water added is 2-120 ml; the frequency of ultrasonication using a water bath ultrasonic device is 40 kHz, and the temperature of ultrasonication is 20-30°C.

3. The method for preparing high-purity ZrC powder on a large scale according to claim 1, characterized in that: In the step S2, the organic ligand is pyromellitic acid; the amount of the organic ligand added is 1-60 mmol; and the amount of the ethanol added is 2-120 ml.

4. The method for preparing high-purity ZrC powder on a large scale according to claim 1, characterized in that: In the step S3, the organic solution is poured into the metal salt solution for mixing; after obtaining the metal organic sol, the solution is allowed to stand for 1 to 48 hours.

5. The method for preparing high-purity ZrC powder on a large scale according to claim 1, characterized in that: In the step S4, the amount of ammonia water added is 50-30000ul; and the standing time is 1-48h.

6. The method for preparing high-purity ZrC powder on a large scale according to claim 1, characterized in that: In step S5, the drying temperature in the high temperature oven is 120° C. and the drying time is 12 to 24 hours.

7. The method for preparing high-purity ZrC powder on a large scale according to claim 1, characterized in that: In step S6, the rotation speed of the centrifuge is 8000 rpm, the centrifugal cleaning time is 5 min, and the centrifugal cleaning is performed 3 times.

8. The method for preparing high-purity ZrC powder on a large scale according to claim 1, characterized in that: In step S6, the drying temperature in the high temperature oven is 120° C. and the drying time is 12 to 24 hours.

9. The method for preparing high-purity ZrC powder on a large scale according to claim 1, characterized in that: In step S7, the cracking process is as follows: the heating rate of the vacuum carbon tube furnace is 5-20°C / min, firstly, the temperature is kept at 800°C for 1-6 hours, and then at 1400-1700°C for 1-3 hours; at the same time, the cracking is carried out in a negative pressure argon environment, the flow rate of the argon is 100-300 sccm, and the negative pressure environment is less than 100 Pa.

10. A ZrC powder, characterized in that: The ZrC powder is processed by the preparation method for large-scale preparation of high-purity ZrC powder as described in any one of claims 1 to 9.

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