阅读说明：本技术 一种纳米硼化铪粉体的制备方法 (Preparation method of nano hafnium boride powder ) 是由 王振 黄竹林 李昕扬 胡晨光 胡小晔 李越 于 2021-07-27 设计创作，主要内容包括：本发明属于纳米材料制备领域,尤其涉及一种新型共沉淀法制备硼化铪粉体的方法。具体流程为：(1)将HfCl-(4)溶于乙酸得到透明溶液A；将硼酸、D-山梨醇溶于醋酸中,搅拌至完全溶解,得到透明溶液B；(2)待B溶液冷却至室温后,向溶液中逐滴加A并搅拌,有白色絮状物析出,溶液变成乳白色；(3)将溶胶烘干；(4)充分研磨得到白色粉末的硼化铪前驱体；(5)将硼化铪前驱体高温下煅烧得到硼化铪纳米粉体。本发明的制备方法操作简单,条件容易控制,生产周期短；制得的硼化铪粉体粒径为纳米级且分布均匀,具有良好的形貌特征以及超高的纯度,产率高。为实现高性能、高强度,超高温陶瓷材料的工程化、产业化制备提供了技术基础。(The invention belongs to the field of nano material preparation, and particularly relates to a novel method for preparing hafnium boride powder by a coprecipitation method. The specific process is as follows: (1) reacting HfCl 4 Dissolving in acetic acid to obtain a transparent solution A; dissolving boric acid and D-sorbitol in acetic acid, and stirring until the boric acid and the D-sorbitol are completely dissolved to obtain a transparent solution B; (2) after the solution B is cooled to room temperature, dropwise adding the solution A into the solution, stirring, and separating out white floccules to obtain milky solution; (3) drying the sol; (4) fully grinding to obtain a white powdery hafnium boride precursor; (5) and calcining the hafnium boride precursor at high temperature to obtain the hafnium boride nano powder. The preparation method of the invention has simple operation, easy control of conditions and short production period; the particle size of the prepared hafnium boride powder is nano-gradeUniform distribution, good appearance characteristics, ultrahigh purity and high yield. Provides a technical basis for the engineering and industrial preparation of the high-performance, high-strength and ultrahigh-temperature ceramic material.)

1. A preparation method of nano hafnium boride powder is characterized by comprising the following steps:

s1, pouring the mixed powder of boric acid and sorbitol into acetic acid, wherein the mass ratio of boric acid to sorbitol to acetic acid is 2 (2.8-3.8):10, stirring at the constant temperature of 60-90 ℃ to completely dissolve the boric acid and sorbitol into the acetic acid, thereby obtaining a clear mixed solution A, and cooling to the room temperature;

s2, mixing hafnium chloride and acetic acid according to the mass ratio of 3 (5-10), and stirring to obtain a clear light yellow mixed solution B;

s3, slowly dropping the mixed solution B into the mixed solution A at a constant speed of 1-10mL/min, wherein the mixing mass ratio of the mixed solution A, B is 1 (0.5-1.0), and continuously stirring to prepare milky hafnium boride precursor precipitate mixed solution;

s4, placing the mixed solution of the hafnium boride precursor precipitate into a constant-temperature drying box at the temperature of 100-150 ℃, and drying the mixed solution until the mixed solution is completely dried to obtain the hafnium boride precursor precipitate;

s5, grinding the hafnium boride precursor precipitate into powder, and calcining the powder for 60-120min at 1500-1650 ℃ in a high-temperature tube furnace by taking high-purity argon as protective gas to obtain high-purity hafnium boride powder;

wherein, the steps S1 and S2 are not in sequence.

2. The method for preparing nano hafnium boride powder according to claim 1, wherein the stirring manner in step S1 is magnetic stirring.

3. The method as claimed in claim 1, wherein the drying temperature at constant temperature in step S4 is 110-130 ℃.

4. The method according to claim 1, wherein the purity of the hafnium chloride and the acetic acid in step S2 is analytical grade.

5. The method for preparing hafnium boride nanoparticles as claimed in claim 1, wherein the high temperature calcination in step S5 is performed by gradient heating at a rate of 5-10 ℃/min from room temperature to 1000 ℃, then at a rate of 2-5 ℃/min to 1500-.

Technical Field

The invention belongs to the technical field of nano material preparation, and particularly relates to a novel method for preparing nano hafnium boride powder by a coprecipitation method.

Background

Hafnium diboride (HfB)₂) With hexagonal AlB₂The layered structure contains B atoms in a two-dimensional graphite ring, and hexagonal tightly-filled Hf layers are alternately formed, strong Hf-B ionic bonds and B-B covalent bonds lead to excellent characteristics of ultra-high melting point at 3250 ℃, high oxidation resistance, high hardness and the like, and the layered structure is one of the best candidate materials for hypersonic aircrafts, rocket propulsion systems, cutting tools, wear-resistant coatings, molten metal crucibles, plasma arc electrodes, nuclear reactor neutron absorbers and the like. However, the grain diameter of the existing commercial boride powder is tens of microns, the purity of the product is generally lower than 90 wt% after detection, and the product is basically blank in the aspect of development of high-purity superfine submicron boride ultrahigh-temperature ceramic powder, so that the sintering and comprehensive performance of the material are severely restricted.

At present, HfB₂The preparation method mainly comprises the following steps: direct reaction of elemental boron with hafnium [ j.am.ceramic. soc.2008,91,1481; j. mater.sci.2017,52,12689]Self-propagating synthesis method, carbon/boron thermal reduction method [ j.am.ceramic.soc.2008, 91,2709]And molten salt assisted synthesis method [ J.Adv.Mater.2020,9,35]And the like. For example, Blum et al, the American air force scientific research office, adopted homogeneous and heterogeneous reactions of hafnium (Hf) with boron (B) or carbon (C) powders under non-self-propagating high temperature synthesis (SHS) conditions to explore chemically assisted processes for ultra-high temperature ceramics under mild practical conditions. The threshold interactions of the Hf/B and Hf/C powder mixtures of relatively large Hf particle compositions occurred at around 700 ℃ and 800 ℃, respectively, but the synthesized hafnium boride powder had a large number of unknown impurities, although the single elements used reacted directly. Researchers in Shanghai silicon institute adopt a modified carbon thermal/boron temperature reduction method to calcine at a relatively low temperature (1600 ℃) to obtain 1HfB of micron₂Powder with low oxygen content (0.30 wt%). Researchers at southern China university of Engineers at 1100 deg.C with B and HfO₂As a precursor, HfB with the average grain diameter of 155nm of nanocrystalline is successfully synthesized in KCl/NaCl molten salt by adopting a molten salt synthesis technology₂Powder and demonstrates the substance diffusion mechanism in the molten salt-assisted synthesis [ J.Adv.Mater.2020,9,35]。

In general, the process can obtain HfB due to the special crystal structure and physical and chemical properties of hafnium boride₂The powder generally has the problem that the purity and the particle size are difficult to balance. High-purity products can be obtained at high temperature, but hundred-nanometer-level superfine powder is difficult to obtain due to sintering effect, and the low-temperature synthesis method is difficult to ensure that the full production is generated so as to introduce the mixed phases of hafnium carbide, hafnium oxide and the like. Meanwhile, considering that the superfine ceramic powder is beneficial to subsequent densification sintering and molding, the method has low cost and large-scale synthesis of the high-purity superfine HfB₂The powder method is still worth exploring.

Disclosure of Invention

The invention aims to overcome the defects of difficult balance of purity and grain size and high manufacturing cost of hafnium boride powder in the prior art and provides a preparation method of nano hafnium boride powder.

In order to solve the technical problem of the invention, the technical scheme is that the preparation method of the nano hafnium boride powder comprises the following steps;

s1, pouring the mixed powder of boric acid and sorbitol into acetic acid, wherein the mass ratio of boric acid to sorbitol to acetic acid is 2 (2.8-3.8):10, stirring at the constant temperature of 60-90 ℃ to completely dissolve the boric acid and sorbitol into the acetic acid, thereby obtaining a clear mixed solution A, and cooling to the room temperature;

s2, mixing hafnium chloride and acetic acid according to the mass ratio of 3 (5-10), and stirring to obtain a clear light yellow mixed solution B;

s3, slowly dropping the mixed solution B into the mixed solution A at a constant speed of 1-10mL/min, wherein the mixing mass ratio of the mixed solution A, B is 1 (0.5-1.0), and continuously stirring to prepare milky hafnium boride precursor precipitate mixed solution;

s4, placing the mixed solution of the hafnium boride precursor precipitate into a constant-temperature drying box at the temperature of 100-150 ℃, and drying the mixed solution until the mixed solution is completely dried to obtain the hafnium boride precursor precipitate;

s5, grinding the hafnium boride precursor precipitate into powder, and calcining the powder for 60-120min at 1500-1650 ℃ in a high-temperature tube furnace by taking high-purity argon as protective gas to obtain high-purity hafnium boride powder;

wherein, the steps S1 and S2 are not in sequence.

The further technical proposal of the preparation method of the nano hafnium boride powder is as follows:

preferably, the stirring manner in step S1 is magnetic stirring.

Preferably, the temperature of the constant temperature drying in the step S4 is 110-130 ℃.

Preferably, the purity of the hafnium chloride and the acetic acid in step S2 is analytical grade.

Preferably, the high-temperature calcination in the step S5 is performed by heating in a gradient manner at a rate of 5-10 ℃/min from room temperature to 1000 ℃, then heating at a rate of 2-5 ℃/min to 1550 ℃, performing heat preservation calcination at 1550 ℃ for 30min, then cooling at a rate of 2-5 ℃/min to 1000 ℃, then cooling at a rate of 5-10 ℃/min to 300 ℃, and finally naturally cooling to room temperature.

Compared with the prior art, the invention has the beneficial effects that:

1) aiming at the difficulty of developing hafnium boride powder products, the invention provides a coprecipitation method for preparing ultrapure nano HfB₂A method for synthesizing powder. Firstly, boric acid and sorbitol are used as raw materials to form sol in an acetic acid system, hafnium chloride is used as a hafnium source to be dissolved in a solvent acetic acid, the boric acid and the sorbitol react to form a complex after the boric acid and the sorbitol are mixed with each other to form a boron complex, the boron complex is solidified, and the sorbitol and the acetic acid undergo esterification reaction to form a small amount of water; as the chloride ions of the hafnium chloride are replaced with the carboxyl of the acetic acid, a small amount of products generate a framework of-Hf-O-Hf-through hydrolysis reaction, and a large amount of products continue to react with the complex of boron to generate molecular-level uniformly dispersed-Hf-O-C-B-precipitates. The precipitate is fully dried and ground into powder, and then put into a high-temperature tube furnaceHigh-temperature calcination, wherein the high-temperature calcination can fully carry out the carbothermic reduction reaction, and the high-purity superfine hafnium boride powder can be prepared.

2) The method for preparing the hafnium boride powder by the coprecipitation method directly obtains the ceramic precursor product with uniform chemical components through various complex reactions in the solution, and because the precipitate only contains a single component, the operation is simple, the conditions are easy to control, the yield is high, the production period is short, the nano powder material with small granularity and uniform distribution is easy to prepare, and the prepared hafnium boride powder has nano-scale size, good morphological characteristics and ultrahigh purity. The preparation process is relatively simple, does not need special instruments and medicines, does not relate to complex processing steps, is suitable for large-scale synthesis of the ultrahigh-temperature ceramic material, and has the potential of engineering preparation. Provides a technical basis for the engineering and industrial preparation of the high-performance, high-strength and ultrahigh-temperature ceramic material.

3) Microstructure analysis and detection of the product show that the hafnium boride powder prepared by the method has uniform size and good spherical particle microstructure, the particle size of the hafnium boride powder is about 100-500nm, and data are compared with a standard value in JCPDS Powder Diffraction File (PDF) through X-ray diffraction (XRD) detection, so that the hexagonal HfB₂The reference spectrum of the PDF card 75-1049 shows diffraction peaks of single-phase hafnium boride, and no signs of other impurities are observed.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed to be used in the description of the embodiments are briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on the drawings without creative efforts.

Fig. 1 is a scanning electron micrograph and an XRD pattern obtained by respectively subjecting the hafnium boride powder prepared in example 1 of the present invention to different magnifications using a scanning electron microscope and an X-ray diffraction analyzer.

FIG. 2 is an EDS element distribution diagram of hafnium boride powder prepared by the embodiment of the invention by using a scanning electron microscope.

Fig. 3 is a scanning electron microscope photograph obtained by performing morphology detection on the hafnium boride powder prepared in example 2 of the present invention under different magnifications by using a scanning electron microscope.

FIG. 4 is an EDS elemental content photograph and an XRD spectrum of the hafnium boride powder prepared in example 2 of the present invention, respectively, using a scanning electron microscope and an X-ray diffraction analyzer.

Fig. 5 is an XRD spectrum obtained by using an X-ray diffraction analyzer to perform substance detection on the hafnium boride powders prepared in examples 3 and 4 of the present invention, respectively.

Fig. 6 is a scanning electron microscope photograph obtained by performing morphology detection on the hafnium boride powder prepared in embodiments 3 and 4 of the present invention at magnifications of 60k and 20k, respectively, by using a scanning electron microscope.

Detailed Description

The technical solutions in the embodiments of the present invention are clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments of the present invention without making any creative effort, shall fall within the protection scope of the present invention.

The method for preparing hafnium boride powder by coprecipitation method provided by the present invention is described in detail below. Details which are not described in detail in the embodiments of the invention belong to the prior art which is known to the person skilled in the art.

Example 1

A method for preparing hafnium boride powder by a coprecipitation method comprises the following steps:

step S1, weighing 2.0g of boric acid and 3.5g of sorbitol, putting into the same beaker for mixing, then pouring 10mL of acetic acid (analytically pure) into the beaker, gradually heating to 80 ℃ under the oil bath heating condition by using a magnetic stirrer, stirring at constant temperature until the boric acid and the sorbitol are completely dissolved in the acetic acid and the solution is completely clarified, thus obtaining a clarified mixed solution A, and cooling to room temperature;

s2, weighing 6mL of acetic acid (analytically pure) and pouring the acetic acid into a beaker, weighing 3.2g of hafnium chloride and slowly pouring the hafnium chloride into the beaker, and continuously stirring to obtain a light yellow transparent mixed solution B;

step S3, slowly dripping the mixed solution B into the mixed solution A at a constant speed of 1mL/min under the condition that the mixed solution A is continuously stirred, so as to obtain a precursor of the white hafnium boride precipitate;

s4, putting the hafnium boride precursor precipitate mixture into a constant-temperature drying oven, and drying at 120 ℃ for 12h to completely dry the mixture so as to obtain a hafnium boride precursor precipitate;

step S5, grinding the hafnium boride precursor into powder, then placing the powder into a graphite crucible, placing the graphite crucible into a high-temperature tube furnace, taking high-purity argon (Ar is more than or equal to 99.999%) as protective gas, heating the powder from room temperature to 1000 ℃ at the speed of 5 ℃/min, then heating the powder to 1550 ℃ at the speed of 2 ℃/min, preserving the heat for 30min, then cooling the powder to 1000 ℃ at the speed of 2 ℃/min, then cooling the powder to 300 ℃ at the speed of 5 ℃/min, and finally naturally cooling the powder to room temperature to obtain the hafnium boride powder.

Example 2

A method for preparing hectogram hafnium boride powder by a coprecipitation method comprises the following steps:

step S1, weighing 20g of boric acid and 35g of sorbitol, putting into the same beaker, mixing, pouring 100mL of acetic acid (analytically pure), gradually heating to 80 ℃ by using an oil bath magnetic stirrer, stirring at constant temperature until the boric acid and the sorbitol are completely dissolved in the acetic acid and the solution is completely clarified, so as to obtain a clarified mixed solution A, and cooling to room temperature;

step S2, weighing 80mL of acetic acid (analytically pure) and pouring the acetic acid into a beaker, weighing 32g of hafnium chloride and slowly pouring the hafnium chloride into the beaker, and continuously stirring to obtain a light yellow transparent mixed solution B;

step S3, slowly dripping the mixed solution B into the mixed solution A at a constant speed of 5mL/min under the condition that the mixed solution A is continuously stirred, thereby obtaining a precursor of the white hafnium boride precipitate;

s4, putting the hafnium boride precursor precipitate mixture into a constant-temperature drying oven, and drying at 120 ℃ for 12h to completely dry the mixture so as to obtain a hafnium boride precursor precipitate;

and S5, grinding the hafnium boride precursor into powder by using a planetary ball mill, then placing the powder into a graphite crucible, placing the graphite crucible into a high-temperature tube furnace, taking high-purity argon (Ar is more than or equal to 99.999%) as protective gas, heating from room temperature to 1000 ℃ at the speed of 5 ℃/min, heating to 1550 ℃ at the speed of 2 ℃/min, preserving heat for 30min, cooling to 1000 ℃ at the speed of 2 ℃/min, cooling to 300 ℃ at the speed of 5 ℃/min, and finally naturally cooling to room temperature to obtain the hafnium boride powder.

Example 3

A method for preparing hafnium boride powder by a coprecipitation method comprises the following steps:

step S1, weighing 2.0g of boric acid and 3.8g of sorbitol, putting into the same beaker for mixing, then pouring 10mL of acetic acid (analytically pure) into the beaker, gradually heating to 60 ℃ under the oil bath heating condition by using a magnetic stirrer, stirring at constant temperature until the boric acid and the sorbitol are completely dissolved in the acetic acid and the solution is completely clarified, thus obtaining a clarified mixed solution A, and cooling to room temperature;

s2, measuring 8mL of acetic acid (analytically pure) and pouring the acetic acid into a beaker, weighing 3.0g of hafnium chloride and slowly pouring the hafnium chloride into the beaker, and continuously stirring to obtain a light yellow transparent mixed solution B;

step S3, slowly dripping the mixed solution B into the mixed solution A at a constant speed of 1mL/min under the condition that the mixed solution A is continuously stirred, so as to obtain a precursor of the white hafnium boride precipitate;

s4, putting the hafnium boride precursor precipitate mixture into a constant-temperature drying oven, and drying at 130 ℃ for 6 hours to completely dry the mixture so as to obtain a hafnium boride precursor precipitate;

and step S5, grinding the hafnium boride precursor into powder, then placing the powder into a graphite crucible, placing the graphite crucible into a high-temperature tube furnace, taking high-purity argon (Ar is more than or equal to 99.999%) as protective gas, heating the powder from room temperature to 1000 ℃ at the speed of 5 ℃/min, heating the powder to 1500 ℃ at the speed of 2 ℃/min, preserving the temperature for 120min, cooling the powder to 1000 ℃ at the speed of 2 ℃/min, cooling the powder to 300 ℃ at the speed of 5 ℃/min, and finally naturally cooling the powder to room temperature to obtain the hafnium boride powder.

Example 4

A method for preparing hafnium boride powder by a coprecipitation method comprises the following steps:

step S1, weighing 1.8g of boric acid and 3.5g of sorbitol, putting into the same beaker for mixing, then pouring 10mL of acetic acid (analytically pure) into the beaker, gradually heating to 80 ℃ under the oil bath heating condition by using a magnetic stirrer, stirring at constant temperature until the boric acid and the sorbitol are completely dissolved in the acetic acid and the solution is completely clarified, thus obtaining a clarified mixed solution A, and cooling to room temperature;

s2, measuring 8mL of acetic acid (analytically pure) and pouring the acetic acid into a beaker, weighing 3.2g of hafnium chloride and slowly pouring the hafnium chloride into the beaker, and continuously stirring to obtain a light yellow transparent mixed solution B;

step S3, slowly dripping the mixed solution B into the mixed solution A at a constant speed of 2mL/min under the condition that the mixed solution A is continuously stirred, so as to obtain a precursor of the white hafnium boride precipitate;

s4, putting the hafnium boride precursor precipitate mixture into a constant-temperature drying oven, and drying at 140 ℃ for 6 hours to completely dry the mixture so as to obtain a hafnium boride precursor precipitate;

step S5, grinding the hafnium boride precursor into powder, then placing the powder into a graphite crucible, placing the graphite crucible into a high-temperature tube furnace, taking high-purity argon (Ar is more than or equal to 99.999%) as protective gas, heating the powder from room temperature to 1000 ℃ at the speed of 5 ℃/min, then heating the powder to 1650 ℃ at the speed of 2 ℃/min, preserving the heat for 60min, then cooling the powder to 1000 ℃ at the speed of 2 ℃/min, then cooling the powder to 300 ℃ at the speed of 5 ℃/min, and finally naturally cooling the powder to room temperature to obtain the hafnium boride powder.

The hafnium boride powder obtained in the embodiment 1 and the embodiment 2 of the present invention after the scale up is subjected to purity detection and morphology observation, so as to obtain the following results:

fig. 1 is a scanning electron micrograph and an XRD pattern obtained by respectively subjecting the hafnium boride powder prepared in example 1 of the present invention to different magnifications using a scanning electron microscope and an X-ray diffraction analyzer. Wherein, FIG. 1 (a) is an FESEM photograph of the hafnium boride powder prepared in example 1 of the present invention at a magnification of 60 k; FIG. 1(b) is a diagram showing boronation obtained in example 1 of the present inventionFESEM photograph of hafnium powder under 20k of magnification; FIG. 1(c) is an FESEM photograph of the hafnium boride powder prepared in example 1 of the present invention at a magnification of 5 k; FIG. 1(d) is an XRD spectrum of the hafnium boride powder obtained in example 1 of the present invention. SEM picture of the hafnium boride powder obtained in example 1 of the present invention shows that HfB obtained by calcination₂The particle size of the particles is about 100nm to 400nm, the size and the appearance of the particles are uniform, the shape of the particles is circular, and the particle boundaries are clear. XRD results are shown in figure 1(d), and the single-phase nano HfB prepared by the coprecipitation method can be obtained₂The purity of the powder particles is high, and other obvious impurity peaks are not found.

FIG. 2 is an EDS element distribution diagram of hafnium boride powder prepared by the embodiment of the invention by using a scanning electron microscope. The hafnium boride powder prepared in the embodiment 1 of the present invention has uniform distribution of boron and hafnium elements and no aggregation phenomenon.

Fig. 3 is a scanning electron microscope photograph obtained by performing morphology detection on the hafnium boride powder prepared in example 2 of the present invention under different magnifications by using a scanning electron microscope. FIG. 3(a) is an FESEM photograph of the hafnium boride powder prepared in example 2 of the present invention at a magnification of 60 k; FIG. 3(b) is an FESEM photograph of the hafnium boride powder prepared in example 2 of the present invention at a magnification of 20 k; the hafnium boride powder prepared in the embodiment 2 of the invention has a substantially uniform spherical particle in microscopic morphology, a substantially uniform particle size, and a fusion phenomenon among partial particles. Analysis of FESEM pictures shows that the particle size is about 200-500nm, i.e. the powder prepared is in submicron level without subsequent crushing and classification treatment.

FIG. 4 is an EDS elemental content photograph and an XRD spectrum of the hafnium boride powder prepared in example 2 of the present invention, respectively, using a scanning electron microscope and an X-ray diffraction analyzer. Compared with a standard PDF card, the amplified hectogram hafnium boride powder shows single-phase hexagonal phase hafnium boride without any impurity peak on an XRD (X-ray diffraction) map, and EDS (electron-dispersive spectroscopy) boron elements and hafnium elements are uniformly distributed without aggregation. The mass ratio analysis of EDS element components shows that all the elements are boron and hafnium, the mass ratio is about Hf: B-9: 1, and the component is HfB₂。

FIG. 5(a) is an XRD spectrum of the hafnium boride powder obtained in example 3 of the present invention. FIG. 5(b) is an XRD spectrum of the hafnium boride powder obtained in example 4 of the present invention. As can be seen from fig. 5: in the embodiments 3 and 4 of the invention, different process conditions are changed, and the prepared hafnium boride powder shows single-phase hafnium boride on an XRD (X-ray diffraction) spectrum without any impurity peak phase.

Fig. 6 is a scanning electron microscope photograph obtained by performing morphology detection on the hafnium boride powder prepared in embodiments 3 and 4 of the present invention under different magnifications. FIG. 6(a) is an FESEM photograph at a magnification of 60k of the hafnium boride powder prepared in example 3 of the present invention; FIG. 6(b) is an FESEM photograph of the hafnium boride powder prepared in example 3 of the present invention at a magnification of 10 k; FIG. 6(c) is an FESEM photograph at a magnification of 60k of the hafnium boride powder obtained in example 4 of the present invention; FIG. 6(d) is an FESEM photograph of the hafnium boride powder obtained in example 4 of the present invention at a magnification of 10 k. As can be seen from fig. 1 and 6: the proportion of the carbon source is increased, and the micro appearance of the hafnium boride powder prepared in the comparative example 3 is mostly uneven and accompanied with amorphous carbon blocks; the micro-morphology of the hafnium boride powder prepared in the embodiment 4 of the invention is more in a small block shape due to the increase of the calcination temperature, and is more uniform. The hafnium boride powder prepared in the embodiment 1 of the present invention has a substantially uniform spherical particle in microscopic morphology.

The result shows that the high-purity single-phase HfB can be prepared under the condition of low-temperature (1550 ℃) atmosphere calcination by adopting a coprecipitation method through regulating the formula and the preparation process of the sol₂And (3) nano powder. In addition, the embodiment of the invention has simple preparation process, does not relate to complex reaction process, can be prepared in short period and low raw material price, and the prepared HfB₂The powder has high purity, fine particle size and good micro-morphology, and can provide a technical basis and a commercial potential for large-scale synthesis of the ultrahigh-temperature ceramic material.

The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are included in the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.