Preparation method of hafnium boride powder with three-dimensional hollow tubular structure

Abstract

The present invention discloses a preparation method of hafnium boride powder with a three-dimensional hollow tubular structure, which is prepared by using boric acid and hafnium oxide as raw materials through a sol-assisted mechanical grinding method. The preparation process of the present invention is simple, does not involve complex reaction processes, does not require special instruments and drugs, has a short production cycle, and low raw material prices. Moreover, the prepared hafnium boride powder has high purity and a uniform and good micro-morphology, and can provide a technical basis and commercial potential for the large-scale synthesis of ultra-high temperature ceramic materials.

Description

Technical Field

[0001] The present invention belongs to the technical field of ultra-high temperature ceramic powder preparation, and particularly relates to a method for preparing hafnium boride powder with a three-dimensional hollow tubular structure. Background Art

[0002] Ultra-high temperature ceramics (UHTCs), having extremely high melting points, high Young's moduli, high hardnesses, and high thermal conductivities, are used in reentry vehicle thermal protection materials and other high-temperature thermal insulation fields. In particular, hafnium boride (HfB 2 ) powder, due to its high melting temperature, excellent wear resistance, and corrosion resistance, makes it a potential candidate material for use in hypersonic aerospace vehicles. However, the properties and applications of ceramic nanomaterials are greatly affected by their morphologies, so it is very important to controllably synthesize nanostructures with various particle morphologies.

[0003] Currently, ultra-high temperature ceramic powders are mainly used as second-phase dopants to form composite materials. Conventional boride ceramic powders are granular or flaky, and often need to be toughened and the specific surface area increased during subsequent forming applications to improve their mechanical properties and overcome the deficiencies in the mechanical properties and sintering ability of composite materials. And hafnium boride powder is mainly spherical and rod-shaped in addition to irregular morphologies. It is of great significance to prepare hafnium boride powder with a hollow tubular structure having a three-dimensional structure and a large specific surface area. Summary of the Invention

[0004] The purpose of the present invention is to provide a method for preparing HfB 2 powder with a three-dimensional hollow tubular structure. This method contains only a single component, is simple to operate, the reaction process is easy to control, the production cycle is relatively short, and the prepared hafnium boride powder has high purity and a uniform and good microstructure, providing a technical basis for the preparation of high-performance and high-strength ultra-high temperature composite ceramic materials.

[0005] To achieve the above purpose, the present invention adopts the following technical solutions:

[0006] A method for preparing hafnium boride powder with a three-dimensional hollow tubular structure, comprising the following steps:

[0007] Step 1: Pour the mixed powder of boric acid and sorbitol into acetic acid, and stir at a constant temperature until completely dissolved to obtain a mixed solution A;

[0008] Step 2: Add hafnium oxide to the mixed solution A, and continue to stir evenly at a constant temperature to obtain a mixed solution B;

[0009] Step 3: Place the mixed solution B in an oil bath environment and stir vigorously to foam it and make it gel to obtain a hafnium boride precursor;

[0010] Step 4: Put the hafnium boride precursor obtained in Step 3 into a high-temperature calcination furnace for calcination to obtain hafnium boride powder with a three-dimensional hollow tubular structure.

[0011] Further, in Step 1, the molar ratio of boric acid to sorbitol is 1:0.2 - 0.5.

[0012] Further, in Step 1, the temperature of the constant-temperature stirring is 70 - 90 °C, the stirring method is magnetic stirring, and the rotation speed is 50 - 400 rpm.

[0013] Further, in Step 2, the molar ratio of hafnium oxide to boric acid in Step 1 is 1:2.5 - 6.

[0014] Further, in Step 2, the temperature of the constant-temperature stirring is 70 - 90 °C, the stirring method is magnetic stirring, the rotation speed is 50 - 400 rpm, and the stirring time is 4 - 8 h.

[0015] Further, in Step 3, the oil bath temperature for stirring and foaming is 120 - 150 °C, and the stirring time is 2 - 6 h.

[0016] Further, in Step 4, the calcination is carried out using high-purity argon as the protective gas, the calcination temperature is 1500 - 1700 °C, and the time is 30 - 180 min.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0018] 1. The method for preparing hafnium boride powder by sol-assisted mechanical grinding provided by the present invention has a simple preparation process, does not involve complex reaction processes, does not require special instruments and chemicals, has a short production cycle, and low raw material prices. Moreover, the prepared hafnium boride powder has high purity and a uniform and good micro-morphology. Based on this, it has the potential for large-scale synthesis of ultra-high temperature ceramic materials with mechanical properties such as high toughness and light weight, and has the potential for commercialization and industrialization.

[0019] 2. The nano-powder material prepared by the method of the present invention has a uniform chemical composition, does not show any impurity peaks in the XRD pattern, has high purity, and can be directly used without secondary treatment.

[0020] 3. The three-dimensional hollow tubular structure HfB 2 powder prepared by the method of the present invention has a uniform and good micro-morphology. The branches of the tubular hafnium boride are 2 - 10 μm long, the average diameter is about 1 - 3 μm, the wall thickness of the tube is 100 nm - 3 μm, and the angular distribution range between each tubular structure is 20° - 60°. Description of the Drawings

[0021] To more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0022] Figure 1 In (a)-(c), scanning electron microscope photos of the three-dimensional hollow tubular structure HfB 2 powder prepared in Example 1 of the present invention at different magnifications, and (d) is the XRD pattern.

[0023] Figure 2 In (a)-(b), scanning electron microscope photos of the three-dimensional hollow tubular structure HfB 2 powder prepared in Example 2 of the present invention at different magnifications, and (c) is the XRD pattern.

[0024] Figure 3 In (a)-(b), scanning electron microscope photos of the three-dimensional hollow tubular structure HfB 2 powder prepared in Example 3 of the present invention at different magnifications, and (c) is the XRD pattern.

[0025] Figure 4 In (a)-(b), scanning electron microscope photos of the three-dimensional hollow tubular structure HfB 2 powder prepared in Example 4 of the present invention at different magnifications, and (c) is the XRD pattern. Detailed implementation manners

[0026] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the protection scope of the present invention.

[0027] In the following embodiments, the stirring speed of the magnetic stirrer is 400 rpm.

[0028] Example 1

[0029] This example provides a method for preparing three-dimensional hollow tubular structure hafnium boride powder by sol-assisted mechanical grinding method, including the following steps:

[0030] Step 1: Weigh 3.1 g (0.05 mol) of boric acid and 2.4 g (molar amount of 0.013 mol) of sorbitol and put them into the same beaker for mixing. Then pour 10 mL of acetic acid (analytical pure) into it, and use an oil bath magnetic stirrer to gradually heat it up to 70 °C. Keep stirring magnetically at a constant temperature until the boric acid and sorbitol are completely dissolved in acetic acid and the solution becomes completely clear, obtaining a mixed solution A.

[0031] Step 2: Weigh 2 g of hafnium oxide (molar amount of 0.01 mol) and add it to the mixed solution A. Use an oil bath magnetic stirrer to heat it up to 80 °C and keep stirring magnetically at a constant temperature for 4 h to obtain a mixed solution B.

[0032] Step 3: Transfer the mixed solution B to an oil bath environment at 130 °C and keep stirring for 4 h to make it foam and then gel, obtaining a hafnium boride precursor.

[0033] Step 4: Directly put the hafnium boride precursor into a graphite crucible, place it in a high-temperature tube furnace, use high-purity argon (Ar≥99.999%) as the protective gas, heat it from room temperature to 1550 °C at a rate of 5 °C / min, keep it at a constant temperature for 60 min, and finally cool it naturally to room temperature to obtain hafnium boride powder with a three-dimensional hollow tubular structure.

[0034] Example 2

[0035] This example provides a method for preparing hafnium boride powder with a three-dimensional hollow tubular structure by a sol-assisted mechanical grinding method, including the following steps:

[0036] Step 1: Weigh 1.8 g (molar amount of 0.029 mol) of boric acid and 2.0 g (molar amount of 0.011 mol) of sorbitol and put them into the same beaker for mixing. Then pour 10 mL of acetic acid (analytical pure) into it, and use an oil bath magnetic stirrer to gradually heat it up to 70 °C. Keep stirring magnetically at a constant temperature until the boric acid and sorbitol are completely dissolved in acetic acid and the solution becomes completely clear, obtaining a mixed solution A.

[0037] Step 2: Weigh 2 g of hafnium oxide (molar amount of 0.01 mol) and add it to the mixed solution A. Use an oil bath magnetic stirrer to heat it up to 80 °C and keep stirring magnetically at a constant temperature for 4 h to obtain a mixed solution B.

[0038] Step 3: Transfer the mixed solution B to an oil bath environment at 120 °C and keep stirring for 8 h to make it foam and then gel, obtaining a hafnium boride precursor.

[0039] Step 4: Directly put the hafnium boride precursor into a graphite crucible, place it in a high-temperature tube furnace, use high-purity argon (Ar≥99.999%) as the protective gas, heat it from room temperature to 1500 °C at a rate of 5 °C / min, keep it at a constant temperature for 180 min, and finally cool it naturally to room temperature to obtain hafnium boride powder with a three-dimensional hollow tubular structure.

[0040] Example 3

[0041] This example provides a method for preparing hafnium boride powder with a three-dimensional hollow tubular structure by a sol-assisted mechanical grinding method, including the following steps:

[0042] Step 1: Weigh 3.1 g (molar amount of 0.05 mol) of boric acid and 3.2 g (molar amount of 0.0176 mol) of sorbitol and put them into the same beaker for mixing. Then pour 15 mL of acetic acid (analytical pure) into it, and use an oil bath magnetic stirrer to gradually heat it up to 80 °C, and keep stirring magnetically at a constant temperature until the boric acid and sorbitol are completely dissolved in acetic acid and the solution becomes completely clear, obtaining a mixed solution A.

[0043] Step 2: Weigh 2 g of hafnium oxide (molar amount of 0.01 mol) and add it to the mixed solution A. Use an oil bath magnetic stirrer to heat it up to 90 °C and keep stirring magnetically at a constant temperature for 4 h to obtain a mixed solution B.

[0044] Step 3: Transfer the mixed solution B to an oil bath environment at 150 °C and keep stirring for 4 h to make it foam and then gel, obtaining a hafnium boride precursor.

[0045] Step 4: Directly put the hafnium boride precursor into a graphite crucible, place it in a high-temperature tube furnace, use high-purity argon (Ar≥99.999%) as the protective gas, heat it from room temperature to 1600 °C at a rate of 5 °C / min, keep it warm for 120 min, and finally cool it naturally to room temperature, thereby obtaining hafnium boride powder with a three-dimensional hollow tubular structure.

[0046] Example 4

[0047] This example provides a method for preparing hafnium boride powder with a three-dimensional hollow tubular structure by a sol-assisted mechanical grinding method, including the following steps:

[0048] Step 1: Weigh 3.1 g (molar amount of 0.05 mol) of boric acid and 2.4 g (molar amount of 0.0132 mol) of sorbitol and put them into the same beaker for mixing. Then pour 10 mL of acetic acid (analytical pure) into it, and use an oil bath magnetic stirrer to gradually heat it up to 90 °C, and keep stirring magnetically at a constant temperature until the boric acid and sorbitol are completely dissolved in acetic acid and the solution becomes completely clear, obtaining a mixed solution A.

[0049] Step 2: Weigh 2 g of hafnium oxide (molar amount of 0.01 mol) and add it to the mixed solution A. Continue to stir magnetically at a constant temperature of 90 °C for 2 h to obtain a mixed solution B.

[0050] Step 3: Transfer the mixed solution B to an oil bath environment at 150 °C and keep stirring for 6 h to make it foam and then gel, obtaining a hafnium boride precursor.

[0051] Step 4: directly load the hafnium boride precursor into a graphite crucible, place it in a high-temperature tube furnace, use high-purity argon (Ar≥99.999%) as a protective gas, heat from room temperature to 1700°C at a rate of 5°C / min, keep warm for 30 minutes, and finally cool naturally to room temperature to obtain a three-dimensional hollow tubular structure of hafnium boride powder.

[0052] Purity detection and morphology observation were performed on the hafnium boride powders prepared in Examples 1-4 of the present invention, and the following results were obtained:

[0053] Figure 1 (a)-(c) are three-dimensional hollow tubular structures HfB prepared in Example 1 of the present invention. 2 SEM photos of the powder at different magnifications, (d) is the XRD pattern. SEM shows that the calcined HfB 2 The powder is a three-dimensional hollow tubular structure. Different hollow tubular structures share a common center and extend outward in a branched manner. The length of the tubular branch hafnium boride is 5-10μm, the average diameter is about 1-2μm, the wall thickness is 200-500nm, and the angle distribution range between each hollow tubular structure is 20°-60°. The XRD spectrum shows that the prepared three-dimensional tubular HfB 2 The powder has high purity and no other obvious impurities were found.

[0054] Figure 2 (a)-(b) are three-dimensional hollow tubular structures HfB prepared in Example 2 of the present invention. 2 SEM photos of the powder at different magnifications, (c) is the XRD spectrum. SEM shows that the calcined HfB 2 The powder is a three-dimensional hollow tubular structure. Different hollow tubular structures extend outward in a branched manner. The length of the tubular branched hafnium boride is 5-10μm, the average diameter is about 1-2μm, the wall thickness is 2-3μm, and the angle distribution range between each hollow tubular structure is 20°-60°. There are pores of different sizes inside the rod-shaped hafnium boride. The XRD spectrum shows that the prepared three-dimensional tubular HfB 2 The powder has high purity and no other obvious impurities were found.

[0055] Figure 3 (a)-(b) The three-dimensional hollow tubular structure HfB prepared in Example 3 of the present invention 2 SEM photos of the powder at different magnifications, (c) is the XRD spectrum. SEM shows that the calcined HfB 2The powder is a three-dimensional hollow tubular structure. Different hollow tubular structures share a common center and extend outward in a branched manner. The length of the hafnium boride tubular branches is 5 - 10 μm, the average diameter is about 1 - 2 μm, and the wall thickness is 100 - 300 nm. The included angle distribution range between each hollow tubular structure is 20° - 60°, indicating that increasing the boron content can further control its wall thickness. The XRD pattern shows that the prepared three-dimensional tubular HfB 2 The powder has a high purity and no other obvious impurities are found.

[0056] Figure 4 In (a)-(b) of this invention, the scanning electron microscope photos of the three-dimensional hollow tubular structure HfB prepared in Example 4 of the present invention 2 The powder at different magnification levels, and (c) is the XRD pattern. SEM shows that the calcined HfB 2 The powder is a three-dimensional hollow tubular structure. Different hollow tube structures share a common center and extend outward in a branched manner. The length of the hafnium boride tubular branches is 3 - 10 μm, the average diameter is about 1 - 3 μm, and the wall thickness is 500 nm - 1 μm. The included angle distribution range between each hollow tubular structure is 20° - 60°. The XRD pattern shows that the prepared three-dimensional tubular HfB 2 The powder has a high purity and no other obvious impurities are found.

[0057] The results show that by adjusting the sol formulation and preparation process, the present invention can prepare three-dimensional hollow tubular structure HfB 2 nano-powder by sol-assisted mechanical grinding method under high-temperature (1500 - 1700 °C) atmosphere calcination conditions. The embodiments of the present invention not only have a simple preparation process, do not involve complex reaction processes, can be prepared with a short cycle and low raw material prices, but also the prepared hafnium boride three-dimensional structure powder has a high purity and meets the requirements of different hollow structure wall thicknesses, and can provide a technical basis and commercial potential for large-scale synthesis of ultra-high temperature ceramic materials.

[0058] The above is only a preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed by the present invention should be covered by the protection scope of the present invention.

Claims

1. A method for preparing a three-dimensional hollow tubular structure of hafnium boride powder. It is characterized in that The steps include: Step 1, pouring the mixed powder of boric acid and sorbitol into acetic acid, stirring at a constant temperature until completely dissolved, to obtain a mixed solution A; Step 2, adding hafnium oxide to the mixed solution A, and continuing to stir evenly at a constant temperature to obtain a mixed solution B; Step 3, placing the mixed solution B in an oil bath environment and stirring and foaming it fully, wherein the oil bath temperature for stirring and foaming is 120-150° C. and the stirring time is 2-6 hours, so as to gel it and obtain a hafnium boride precursor; Step 4: Place the hafnium boride precursor obtained in step 3 into a high-temperature calcining furnace and calcine to obtain hafnium boride powder with a three-dimensional hollow tubular structure.

2. The method for preparing the three-dimensional hollow tubular structure hafnium boride powder according to claim 1, Features: In step 1, the molar ratio of boric acid to sorbitol is 1:0.2-0.

5.

3. The method for preparing the three-dimensional hollow tubular structure hafnium boride powder according to claim 1, Features: In step 1, the temperature of the constant temperature stirring is 70-90° C., the stirring method is magnetic stirring, and the rotation speed is 50-400 rpm.

4. The method for preparing the three-dimensional hollow tubular structure hafnium boride powder according to claim 1, Features: The molar ratio of hafnium oxide in step 2 to boric acid in step 1 is 1:2.5-6.

5. The method for preparing the three-dimensional hollow tubular structure hafnium boride powder according to claim 1, Features: In step 2, the temperature of the constant temperature stirring is 70-90° C., the stirring method is magnetic stirring, the rotation speed is 50-400 rpm, and the stirring time is 4-8 hours.

6. The method for preparing the three-dimensional hollow tubular structure hafnium boride powder according to claim 1, Features: In step 4, the calcination is carried out using high-purity argon as the protective gas, the calcination temperature is 1500-1700° C., and the time is 30-180 min.

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