High-mobility pure-phase tungsten diboride and its preparation method

Abstract

The present invention discloses a tungsten boride with high fluidity and a pure phase thereof and a preparation method thereof. The method includes: (1) mixing tungsten powder, boron powder and grinding balls for ball milling to obtain a tungsten-boron mixed powder; (2) under an inert atmosphere, subjecting the tungsten-boron mixed powder to pressure sintering to obtain a pure-phase tungsten boride powder; (3) self-mixing the pure-phase tungsten boride powder; (4) screening the self-mixed tungsten boride powder to obtain a tungsten boride with high fluidity and a pure phase. The tungsten boride prepared by this method has a single phase and no other impurity phases, and at the same time has high fluidity.

Description

Technical Field

[0001] The invention belongs to the technical field of material preparation, and in particular relates to high-fluidity pure-phase tungsten diboride and a preparation method thereof. Background Art

[0002] Tungsten-boron compounds have a wide range of applications due to their high melting point, high hardness, high electrical conductivity and excellent wear resistance. At the same time, thanks to the high atomic number of tungsten, it has a good shielding effect on gamma rays, and the boron element has a high neutron absorption cross-section and a wide absorption energy range, making tungsten-boron compounds a new type of nuclear shielding material that can shield both gamma rays and neutrons.

[0003] However, there are many types of tungsten-boron compounds, including W 2 B.W.B.W.B. 2 , W 2 B 5 、WB 4 Etc. Therefore, the preparation of tungsten boron compounds with a single phase is now a difficulty in this field. In addition, the fluidity of tungsten boron compound powder directly determines the breadth of its application field. High-fluidity powder can be used as raw material powder for plasma spheroidization and thermal spraying. High-fluidity powder has advantages over ordinary powder in terms of powder feeding difficulty and powder feeding uniformity. However, because tungsten borides are mostly prepared by high-temperature solid-phase synthesis, they are usually subject to the influence of raw material powder properties, and the fluidity of the prepared tungsten borides is poor, which cannot meet the powder feeding requirements of plasma spheroidization and thermal spraying.

[0004] Therefore, the existing preparation method of tungsten boride needs to be improved. Summary of the invention

[0005] The present invention aims to solve one of the technical problems in the related art at least to a certain extent. To this end, one object of the present invention is to provide a high-fluidity pure-phase tungsten diboride and a preparation method thereof, wherein the tungsten diboride prepared by the method has a single phase, no other impurities, and high fluidity.

[0006] In one aspect of the present invention, the present invention provides a method for preparing high-flow pure phase tungsten diboride. According to an embodiment of the present invention, the method comprises:

[0007] (1) mixing tungsten powder, boron powder and grinding balls for ball milling to obtain tungsten-boron mixed powder;

[0008] (2) sintering the tungsten-boron mixed powder under pressure in an inert atmosphere to obtain pure phase tungsten diboride powder;

[0009] (3) self-mixing the pure phase tungsten diboride powder;

[0010] (4) Screen the self-mixed pure tungsten boride powder to obtain pure tungsten boride with high fluidity.

[0011] According to the method for preparing pure tungsten boride with high fluidity according to an embodiment of the present invention, by mixing tungsten powder, boron powder and grinding balls and then performing ball milling, ball milling can make the tungsten powder and boron powder fully and evenly mixed. Then, the ball-milled tungsten-boron mixed powder is subjected to pressure sintering under an inert atmosphere. Pressure sintering under an inert atmosphere can reduce the volatilization of boron powder at high temperatures, reduce the waste of raw materials, make the theoretically calculated amount of boron powder more in line with the actual situation, and thus make the prepared tungsten boride powder have a single phase. Then, the pure tungsten boride powder is self-mixed. Self-mixing can make the particles of the tungsten boride powder collide with each other, reduce the particle edges and corners, and improve the fluidity of the tungsten boride powder. Finally, the self-mixed tungsten boride powder is screened. Screening can make the particle size distribution of the tungsten boride powder more concentrated, and obtain pure tungsten boride with high fluidity. Therefore, the tungsten boride prepared by this method has a single phase, no other impurity phases, and high fluidity at the same time.

[0012] In addition, the method for preparing pure tungsten boride with high fluidity according to the above embodiment of the present invention may further have the following additional technical features:

[0013] In some embodiments of the present invention, in step (1), the particle size of the tungsten powder is 15 - 30 μm, and the particle size of the boron powder is 2 - 5 μm. Thus, it is beneficial to evenly mix the tungsten powder and boron powder.

[0014] In some embodiments of the present invention, before step (1), the tungsten powder is pre-screened through an 80 - 325 mesh sieve and the oversize is taken. Thus, tungsten powder with a larger particle size can be screened out, and tungsten powder with a larger particle size has better fluidity.

[0015] In some embodiments of the present invention, in step (1), the molar ratio of the tungsten powder to the boron powder is 1:(2.05 - 2.15).

[0016] In some embodiments of the present invention, in step (1), the ratio of the total mass of the tungsten powder and boron powder to the mass of the grinding balls is 1:(0.2 - 2).

[0017] In some embodiments of the present invention, in step (1), the rotation speed of the ball milling is 100 - 200 r / min, and the time is 10 - 60 min.

[0018] In some embodiments of the present invention, in step (2), the sintering temperature is 1100 - 1600 °C, and the heat preservation time is 1 - 6 h.

[0019] In some embodiments of the present invention, in step (2), the inert atmosphere includes argon or nitrogen, and sintering is carried out under pressure of the inert atmosphere at 0.05 - 0.15 MPa.

[0020] In some embodiments of the present invention, in step (3), the rotation speed of the self - mixing is 20 - 60 Hz, and the time is 15 - 60 min.

[0021] In some embodiments of the present invention, in step (4), the self - mixed tungsten boride powder is passed through a 80 - 325 mesh sieve, and the undersize is taken. Thus, the particle size distribution of the tungsten boride powder is more concentrated, which helps to improve the fluidity of the tungsten boride powder.

[0022] In a second aspect of the present invention, the present invention provides a high - fluidity pure - phase tungsten boride. According to the embodiments of the present invention, the high - fluidity pure - phase tungsten boride is prepared by the above - mentioned method. Thus, the phase of the high - fluidity pure - phase tungsten boride is single without other impurity phases, and at the same time, it has high fluidity.

[0023] The additional aspects and advantages of the present invention will be given in part in the following description, become apparent in part from the following description, or be understood through the practice of the present invention. Brief Description of the Drawings

[0024] The above - mentioned and / or additional aspects and advantages of the present invention will become apparent and be readily understood from the description of the embodiments in conjunction with the following drawings, where:

[0025] Figure 1 is a schematic flow chart of a method for preparing high - fluidity pure - phase tungsten boride according to an embodiment of the present invention;

[0026] Figure 2 is a process flow chart of a method for preparing high - fluidity pure - phase tungsten boride according to an embodiment of the present invention;

[0027] Figure 3 is an XRD pattern of the high - fluidity pure - phase tungsten boride obtained in Example 1;

[0028] Figure 4 is an SEM image of the high - fluidity pure - phase tungsten boride obtained in Example 1. Detailed Description of the Embodiments

[0029] The embodiments described below by referring to the drawings are exemplary and are intended to explain the present invention, and should not be construed as limiting the present invention.

[0030] In one aspect of the present invention, the present invention provides a method for preparing high - fluidity pure - phase tungsten boride. According to the embodiments of the present invention, referring to Figure 1 and Figure 2, the method includes:

[0031] S100: Mix tungsten powder, boron powder and grinding balls and perform ball milling

[0032] In this step, by mixing tungsten powder, boron powder and grinding balls and performing ball milling, tungsten-boron mixed powder can be obtained. Specifically, tungsten powder, boron powder and grinding balls are placed in a horizontal planetary ball milling equipment for ball milling. Among them, the grinding balls can be spherical or quasi-spherical grinding balls. At the same time, the rotation speed of ball milling is 100-200 r / min and the time is 10-60 min.

[0033] Further, the particle size of the tungsten powder is 15-30 μm, and the particle size of the boron powder is 2-5 μm. The inventor found that if the particle size of the tungsten powder is too large, the cost will increase; if the particle size of the tungsten powder is too small, the fluidity of the tungsten powder will be too poor; if the particle size of the boron powder is too large, it is not conducive to uniform mixing with the tungsten powder; if the particle size of the boron powder is too small, agglomeration is likely to occur and it is not conducive to uniform mixing with the tungsten powder.

[0034] Further, the tungsten powder is pre-screened through an 80-325 mesh sieve and the oversize is taken. Specifically, before mixing the tungsten powder, boron powder and grinding balls, the tungsten powder is pre-screened through an 80-325 mesh sieve. The inventor found that pre-screening the tungsten powder and taking the oversize can obtain tungsten powder with a larger particle size, and the tungsten powder with a larger particle size has better fluidity. Thus, on the one hand, it helps to mix uniformly with the boron powder, and on the other hand, it is also beneficial to obtain tungsten boride powder with high fluidity subsequently.

[0035] Further, the molar ratio of tungsten powder to boron powder is 1:(2.05-2.15). The inventor found that if the addition amount of boron powder is too much, it is easy to generate W 2 B 5 heterophase, if the addition amount of boron powder is too little, it is easy to generate WB heterophase.

[0036] Further, the ratio of the total mass of tungsten powder and boron powder to the mass of grinding balls is 1:(0.2-2). The inventor found that if the addition amount of grinding balls is too much, the coarse-grained tungsten powder will be broken, resulting in poor fluidity of the tungsten powder; if the addition amount of grinding balls is too little, the boron powder and tungsten powder will be mixed unevenly, and it is easy to generate heterophase during subsequent sintering.

[0037] S200: Under an inert atmosphere, perform pressure sintering on the tungsten-boron mixed powder

[0038] In this step, under an inert atmosphere, perform pressure sintering on the tungsten-boron mixed powder, and pure-phase tungsten boride powder can be obtained. Specifically, under the protection of an inert atmosphere, the tungsten-boron mixed powder obtained in step S100 is placed in a vacuum high-temperature box furnace for pressure sintering to obtain pure-phase tungsten boride powder. Among them, the inert atmosphere includes argon or nitrogen, and

[0039] The inert atmosphere is pressurized to 0.05-0.15 MPa for sintering. The inventors found that by sintering the tungsten-boron mixed powder under the protection of inert atmosphere pressure, the following boronization reaction occurs between the boron powder and the tungsten powder: W+B=WB, WB+B=WB 2 , avoiding

[0040] The formation of other impurity phases besides tungsten diboride phase.

[0041] Furthermore, the sintering temperature is 1100-1600°C, and the holding time is 1-6 hours. The inventors found that if the sintering temperature is too high, the boronizing reaction is likely to continue, resulting in the formation of an impurity phase with a higher boron molar ratio. If the sintering temperature is too low, the reaction driving force is insufficient, which is likely to lead to an incomplete reaction and the formation of an impurity phase with a lower boron molar ratio.

[0042] 0S300: Self-mixing of pure phase tungsten diboride powder

[0043] In this step, the pure phase tungsten diboride powder obtained in step S100 is self-mixed. Specifically, without adding grinding balls, the pure phase tungsten diboride powder is placed in a mixer for self-mixing. Through self-mixing, the particles of the tungsten diboride powder collide with each other, thereby reducing the particle angles and improving the fluidity of the tungsten diboride powder. The speed of the self-mixing is 20 to 60 Hz, and the time is 15 to 60 minutes.

[0044] 5S400: Screening of pure phase tungsten diboride powder after self-mixing

[0045] In this step, the tungsten diboride powder after self-mixing is sieved, and the sieve residue is taken to obtain high-fluidity pure phase tungsten diboride. Specifically, the tungsten diboride powder after self-mixing is passed through a 80-325 mesh sieve, and the sieve residue is taken. The inventors found that if the mesh number of the sieve is too large, it will result in less sieve residue and a low output-input ratio. In addition, the sieve residue of the high-mesh sieve is

[0046] The particle size of tungsten diboride powder is fine and its fluidity is poor. If the mesh size of the sieve is too small, it will not be able to effectively screen out abnormally coarse particles, and the purpose of making the particle size distribution of tungsten diboride powder more concentrated cannot be achieved.

[0047] In the second aspect of the present invention, the present invention proposes a high-flowability pure-phase tungsten diboride. According to an embodiment of the present invention, the high-flowability pure-phase tungsten diboride is prepared by the above-mentioned method. As a result, the high-flowability pure-phase tungsten diboride has a single phase without other impurities and has high fluidity, and the fluidity can reach more than 9.5s / 50g.

[0048] It should be noted that the characteristics and advantages described above for the method for preparing high-fluidity pure-phase tungsten diboride are also applicable to the high-fluidity pure-phase tungsten diboride, and will not be described in detail here.

[0049] The present invention will be described below with reference to specific embodiments. It should be noted that these embodiments are merely descriptive and do not limit the present invention in any way.

[0050] Example 1

[0051] (1) Tungsten powder with a particle size of 20 μm is passed through an 80-mesh sieve. The tungsten powder on the sieve and boron powder with a particle size of 3 μm are mixed at a molar ratio of 1:2.1, and ball milling is carried out using a horizontal planetary ball milling device. The grinding balls are spherical grinding balls, the ball-to-material ratio is 0.5:1, the rotation speed is 150 r / min, and the mixing ball milling time is 30 min to obtain tungsten-boron mixed powder;

[0052] (2) Under the protection of argon atmosphere with a pressure of 0.10 Mpa, the obtained tungsten-boron mixed powder is placed in a vacuum high-temperature box furnace for sintering. The sintering temperature is 1400 °C, and the holding time is 2 h to obtain pure-phase tungsten boride powder;

[0053] (3) Without adding grinding balls, the obtained pure-phase tungsten boride powder is self-mixed using a mixer. The self-mixing rotation speed is 50 Hz, and the self-mixing time is 30 min;

[0054] (4) The obtained self-mixed pure-phase tungsten boride powder is passed through a 140-mesh sieve, and the material under the sieve is taken to obtain pure-phase tungsten boride powder with a fluidity of 7.69 s / 50 g.

[0055] After testing, the XRD pattern of the finally obtained pure-phase tungsten boride powder with a fluidity of 7.69 s / 50 g is shown in Figure 3 , and the SEM image is shown in Figure 4 .

[0056] From Figure 3 it can be seen that the diffraction peaks of the product correspond exactly to the standard pattern of WB 2 , and there are no other impurity peaks, indicating that the product is pure-phase WB 2 . From Figure 4 it can be seen that the particle sizes between the particles of the tungsten boride powder product are relatively close, and the particle edges and corners are relatively smooth, indicating that the fluidity of the tungsten boride powder is better.

[0057] Example 2

[0058] (1) Tungsten powder with a particle size of 16 μm is passed through a 60-mesh sieve. The tungsten powder on the sieve and boron powder with a particle size of 2.5 μm are mixed at a molar ratio of 1:2.05, and ball milling is carried out using a horizontal planetary ball milling device. The grinding balls are spherical grinding balls, the ball-to-material ratio is 0.2:1, the rotation speed is 100 r / min, and the mixing ball milling time is 10 min to obtain tungsten-boron mixed powder;

[0059] (2) Under the protection of argon atmosphere with a pressure of 0.05 Mpa, the obtained tungsten-boron mixed powder was placed in a vacuum high-temperature box furnace for sintering. The sintering temperature was 1100 °C and the holding time was 1 h to obtain pure-phase tungsten boride powder;

[0060] (3) Without adding grinding balls, the obtained pure-phase tungsten boride powder was self-mixed by a mixer. The self-mixing speed was 20 Hz and the self-mixing time was 15 min;

[0061] (4) The self-mixed pure-phase tungsten boride powder was passed through an 80-mesh sieve, and the undersize was taken to obtain pure-phase tungsten boride powder with a fluidity of 9.28 s / 50 g.

[0062] XRD test and SEM test were carried out on the obtained boride powder. It can be seen from the XRD pattern that the product is pure-phase WB 2 , and it can be seen from the SEM pattern that the fluidity of the tungsten boride powder product is better.

[0063] Example 3

[0064] (1) The tungsten powder with a particle size of 25 μm was passed through a 140-mesh sieve, and the oversize tungsten powder and boron powder with a particle size of 3.5 μm were mixed at a molar ratio of 1:2.08. A horizontal planetary ball mill was used for ball milling. The grinding balls were spherical grinding balls, the ball-to-material ratio was 1.5:1, the rotation speed was 180 r / min, and the mixed ball milling time was 50 min to obtain tungsten-boron mixed powder;

[0065] (2) Under the protection of argon atmosphere with a pressure of 0.12 Mpa, the obtained tungsten-boron mixed powder was placed in a vacuum high-temperature box furnace for sintering. The sintering temperature was 1500 °C and the holding time was 4 h to obtain pure-phase tungsten boride powder;

[0066] (3) Without adding grinding balls, the obtained pure-phase tungsten boride powder was self-mixed by a mixer. The self-mixing speed was 40 Hz and the self-mixing time was 50 min;

[0067] (4) The self-mixed pure-phase tungsten boride powder was passed through a 200-mesh sieve, and the undersize was taken to obtain pure-phase tungsten boride powder with a fluidity of 8.98 s / 50 g.

[0068] XRD test and SEM test were carried out on the obtained boride powder. It can be seen from the XRD pattern that the product is pure-phase WB 2 , and it can be seen from the SEM pattern that the fluidity of the tungsten boride powder product is better.

[0069] Example 4

[0070] (1) Pass the tungsten powder with a particle size of 30 μm through a 325-mesh sieve. Take the tungsten powder on the sieve and boron powder with a particle size of 4 μm and mix them in a molar ratio of 1:2.15. Use a horizontal planetary ball mill for ball milling. The grinding balls are spherical grinding balls, the ball-to-material ratio is 2:1, the rotation speed is 200 r / min, and the mixing ball milling time is 60 min to obtain a tungsten-boron mixed powder;

[0071] (2) Under the protection of argon atmosphere with a pressure of 0.15 Mpa, place the obtained tungsten-boron mixed powder in a vacuum high-temperature box furnace for sintering. The sintering temperature is 1600 °C and the holding time is 6 h to obtain a pure-phase tungsten boride powder;

[0072] (3) Without adding grinding balls, self-mix the obtained pure-phase tungsten boride powder with a mixer. The self-mixing rotation speed is 60 Hz and the self-mixing time is 60 min;

[0073] (4) Pass the self-mixed pure-phase tungsten boride powder through a 325-mesh sieve. Take the material under the sieve to obtain a pure-phase tungsten boride powder with a fluidity of 9.37 s / 50 g.

[0074] Perform XRD testing and SEM testing on the obtained boride powder. It can be seen from the XRD pattern that the product is a pure phase of WB 2 and it can be seen from the SEM image that the fluidity of the tungsten boride powder product is better.

[0075] In the description of this specification, the description with reference to terms such as "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples. In addition, without contradiction, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples.

[0076] Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those of ordinary skill in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present invention.

Claims

1. A method for preparing tungsten boride with high fluidity and pure phase, characterized in that, it includes: (1) Mix tungsten powder, boron powder and grinding balls for ball milling to obtain tungsten-boron mixed powder; (2) Under an inert atmosphere, subject the tungsten-boron mixed powder to pressure sintering to obtain pure-phase tungsten boride powder; (3) Self-mix the pure-phase tungsten boride powder; (4) Screen the self-mixed pure-phase tungsten boride powder to obtain high-fluidity pure-phase tungsten boride; In step (1), the particle size of the tungsten powder is 15-30 μm, and the particle size of the boron powder is 2-5 μm. In step (2), the inert atmosphere includes argon or nitrogen, and sintering is carried out under a pressure of 0.05-0.15 MPa with the inert atmosphere. In step (4), the self-mixed tungsten boride powder is passed through a 80-325 mesh sieve and the undersize is taken.

2. The method according to claim 1, characterized in that, before step (1) is carried out, the tungsten powder is pre-screened through an 80-325 mesh sieve and the oversize is taken.

3. The method according to claim 1, characterized in that, in step (1), the molar ratio of the tungsten powder to the boron powder is 1:(2.05-2.15).

4. The method according to claim 1, characterized in that, in step (1), the ratio of the total mass of the tungsten powder and boron powder to the mass of the grinding balls is 1:(0.2-2).

5. The method according to claim 1, characterized in that, in step (1), the rotation speed of the ball milling is 100-200 r / min, and the time is 10-60 min.

6. The method according to claim 1, characterized in that, in step (2), the sintering temperature is 1100-1600 °C, and the holding time is 1-6 h.

7. The method according to claim 1, characterized in that, in step (3), the self-mixing time is 15-60 min.

8. A high-fluidity pure-phase tungsten boride, characterized in that, the high-fluidity pure-phase tungsten boride is prepared by the method according to any one of claims 1-7.

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