Rapid method for the preparation of transition metal borides

Abstract

The present invention relates to a method for the rapid preparation of transition metal borides, which comprises the steps of: using a tungsten rod as a cathode, and using a mixture of boron powder and metal oxide pressed into a lump as an anode, placing the lump mixture and the tungsten rod in an arc furnace; filling the arc furnace with a buffer gas after evacuating the arc furnace and controlling the arc to start an arc, and controlling the arc furnace to close the arc immediately after igniting the lump mixture, so that the lump mixture undergoes a continuous combustion reaction to obtain transition metal borides. The present invention uses a direct current arc plasma method to prepare the transition metal borides, which has the advantages of simple operation, low cost, environmental friendliness, and controllable reaction atmosphere, and the preparation process is simple, rapid, and has no impact on the environment.

Description

[Technical field]

[0001] The present invention relates to a method for the rapid preparation of transition metal borides, which belongs to the field of nanomaterials by the DC arc method. [Background technology]

[0002] In recent years, transition metal borides (TMBs) have attracted great interest due to their unique mechanical and electrical performance. These compounds have excellent properties such as large bulk modulus, high hardness, ultra-high melting point, good thermal stability, strong oxidation resistance, and excellent electrical transmission performance, and are therefore widely used in the fields of super-combustion press engines, rocket propulsion, high supersonic flight, atmospheric reentry, electromechanical hard coats, and claw and cutter tools. For example, titanium diboride, as one of the emerging engineering ceramic materials, has the characteristics of high hardness, high elastic modulus, high workability, excellent wear resistance, and excellent thermal and electrical conductivity. Baharvandi et al. used B4C and TiB2 as raw materials and pressureless sintered at temperatures of 2050 / 2150 °C to synthesize B4C-TiB2 dual-phase ceramic materials. The addition of TiB2 can reduce the porosity and inhibit grain growth, and the higher the synthesis temperature is, the better the density is for the same TiB2 content.

[0003] Common methods for producing transition metal borides include reducing a mixture of boron halide and metal halide with hydrogen gas, reducing a mixture of boron trioxide and metal oxide with carbon, and reducing metal oxide with electrolytic molten salt and simple boron. The above methods are widely used in producing metal borides, but have some problems. For example, a mixture of boron halide and metal halide can be reduced with hydrogen gas, and a mixture of boron halide and volatile metal halide can be thermally decomposed on a wire in hydrogen gas to produce a small amount of pure metal boride. A relatively large amount of metal borides can be produced by reducing a mixture of diboron trioxide and metal oxide with carbon. However, at high temperatures, the volatility of various oxides is different, which causes changes in the chemical composition, and the product is likely to be contaminated by boron, boron carbide, and carbon generated in the middle. As for the electrolytic molten salt method, this method can produce many metal borides, and some of them have already reached the industrial production level. However, the current efficiency is low, some of the phases and products that may generate borides are difficult to separate purely from the molten salt, and some of the above methods require a long production time and additional processing of impurities generated during the production process.

[0004] Therefore, the prior art still has room for improvement and development. Summary of the Invention [Problem to be solved by the invention]

[0005] In view of the above-mentioned shortcomings of the prior art, the objective of the present application is to provide a rapid method for producing transition metal borides, which aims to solve the technical problems that the conventional production process of transition metal borides is complicated and has a large impact on the environment.

[0006] The rapid synthesis method for transition metal borides of the present invention adopts the following technical solutions:

[0007] A tungsten rod and a mass mixture of boron powder and metal oxide are prepared, and the mass mixture and the tungsten rod are placed in an arc furnace as an anode and a cathode, respectively. The arc furnace is evacuated and then filled with a buffer gas. The arc furnace is controlled to start an arc, and the lumpy mixture is ignited. The arc furnace is immediately controlled to close the arc, and the lumpy mixture is continuously subjected to a combustion reaction to obtain a transition metal boride.

[0008] In the above embodiment, the arc furnace is used to provide a heat source, so that the arc can be closed by igniting one end of the anode, and the reaction proceeds in the form of a combustion wave until the entire anode is completely reacted. The transition metal boride is rapidly produced by the arc plasma method, which has the advantages of simple operation, low cost, environmental friendliness, and controllable reaction atmosphere, so that the production process is simple and has no impact on the environment.

[0009] In some embodiments, the buffer gas is argon gas.

[0010] In some embodiments, the metal oxide is one of tricobalt tetroxide, triiron tetroxide, high nickel oxide, titanium dioxide, and vanadium dioxide.

[0011] In some embodiments, the gap between the bulk mixture and the tungsten rod in the arc furnace is 1 to 3 mm.

[0012] In some embodiments, the discharge current of the arc is 12 to 50 A, and the discharge time of the arc is 1 to 30 s.

[0013] In some embodiments, the degree of vacuum after evacuation of the arc furnace is 3 Pa or less.

[0014] In some embodiments, the gas pressure after the buffer gas is filled is 40 to 80 KPa.

[0015] In some embodiments, the transition metal boride comprises one of nickel boride, cobalt boride, vanadium diboride, and titanium diboride.

[0016] The range of the gap between the lump mixture and the tungsten rod and the range of the gas pressure in the arc furnace can make the arc more stable. The discharge current and discharge time of the arc can be adjusted according to the range of the gap and the pressure to obtain a better production effect of the metal boride. [Brief description of the drawings]

[0017] [Figure 1] 1 is a flow chart of the rapid production method of transition metal borides of the present invention. [Diagram 2] FIG. 1 is a schematic diagram of an arc furnace used in the rapid production method of transition metal borides of the present invention. [Diagram 3] 1 is an X-ray diffraction pattern of nickel boride nanoparticles prepared in Example 1 of the present invention. [Figure 4] FIG. 2 is a transmission electron microscope image of nickel boride nanoparticles prepared in Example 1 of the present invention. [Diagram 5] 1 is an X-ray diffraction pattern of vanadium diboride nanoparticles prepared in Example 2 of the present invention. [Figure 6] FIG. 2 is a transmission electron microscope image of vanadium diboride nanoparticles prepared in Example 2 of the present invention. [Figure 7] 1 is an X-ray diffraction pattern of titanium diboride nanoparticles prepared in Example 3 of the present invention. [Figure 8] FIG. 2 is a transmission electron microscope image of titanium diboride nanoparticles prepared in Example 3 of the present invention. [Figure 9] 1 is an X-ray diffraction pattern of the cobalt boride nanoparticles prepared in Example 4 of the present invention. [Figure 10] FIG. 2 is a transmission electron microscope image of the cobalt boride nanoparticles prepared in Example 4 of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] The present invention will now be described in more detail with reference to the accompanying drawings and specific examples, but the scope of protection of the present invention is not limited to the above.

[0019] As shown in FIG. 1 and FIG. 2, the rapid synthesis method for transition metal borides provided by the present invention includes steps S1 and S2.

[0020] In step S1, a mass mixture of a tungsten rod, boron powder and metal oxide is prepared, and the mass mixture and the tungsten rod are placed in an arc furnace as an anode and a cathode, respectively.

[0021] In step S2, the arc furnace is evacuated, then buffer gas is filled in, and the arc furnace is controlled to start an arc, the lumpy mixture is ignited, and then the arc furnace is controlled to close the arc, so that the lumpy mixture is continuously subjected to a combustion reaction to obtain transition metal boride.

[0022] In the above embodiment, the arc furnace is used to provide a heat source, so that the arc can be closed by igniting one end of the anode, and the reaction takes place in the form of a combustion wave until the entire anode is completely reacted. The transition metal boride is rapidly produced using the arc plasma method, which has the advantages of simple operation, low cost, environmental friendliness, and controllable reaction atmosphere, and the production process is simple and has no impact on the environment.

[0023] Optionally, the buffer gas is argon gas.

[0024] Optionally, the metal oxide is one of tricobalt tetroxide, triiron tetroxide, high nickel oxide, titanium dioxide, and vanadium dioxide.

[0025] Optionally, the gap between the bulk mixture and the tungsten rod in the arc furnace is 1-3 mm.

[0026] Optionally, the discharge current of the arc is 12-50A and the discharge time of the arc is 1-30s.

[0027] Optionally, the vacuum level of the arc furnace after evacuation is 3 Pa or less.

[0028] Optionally, the gas pressure after filling with the buffer gas is 40-80 KPa.

[0029] Optionally, the transition metal boride comprises one of nickel boride, cobalt boride, vanadium diboride, and titanium diboride.

[0030] The range of the gap between the lump mixture and the tungsten rod and the gas pressure range in the arc furnace can make the arc more stable. The discharge current and discharge time of the arc can be adjusted to the above range of the gap and pressure range to obtain a better production effect of metal boride.

[0031] The rapid production method of a transition metal boride provided by the present invention will be described in detail below with reference to specific Examples 1 to 5.

[0032] <Example 1> (1) Manufacturing of discharge anodes A mixture of boron powder and high nickel oxide with a ratio of 6:1 is placed in a mortar and the two materials are mixed uniformly to obtain a mixture, which is then placed in a hydraulic press to compress into a lump mixture.

[0033] (2) The tungsten rod was used as the cathode and the lump mixture as the anode. The tungsten rod and the lump mixture were placed in an arc furnace with a gap of 1 mm between the two electrodes. The arc furnace was evacuated to a vacuum of 3 Pa, the DC arc discharge current was set to 12 A, and the arc was started after filling with 70 KPa of argon gas. The discharge time was set to 1 s, and the reactants on the inner wall of the reaction chamber were collected as nickel boride particles.

[0034] <Example 2> (1) Manufacturing of discharge anodes A mixture of boron powder and vanadium dioxide in a ratio of 8:1 was placed in a mortar and the two materials were mixed uniformly to obtain a mixture, which was then placed in a hydraulic press to compress into a lump mixture.

[0035] (2) Using a tungsten rod as the cathode and the lump mixture as the anode, the tungsten rod and the lump mixture are placed in an arc furnace with a distance of 2 mm between the electrodes. The arc furnace is evacuated to a vacuum of 2 Pa, the DC arc discharge current is set to 20 A, and the arc is started after filling with 80 KPa of argon gas. The discharge time is set to 10 s, and the reactants on the inner wall of the reaction chamber are collected as vanadium diboride particles.

[0036] <Example 3> (1) Manufacturing of discharge anodes A mixture of boron powder and titanium dioxide in a ratio of 4:1 was placed in a mortar to mix the two materials uniformly to obtain a mixture, which was then placed in a hydraulic press to compress into a lump mixture.

[0037] (2) Using the tungsten rod as the cathode and the lump mixture as the anode, the tungsten rod and the lump mixture are placed in an arc furnace with a gap of 3 mm between the electrodes. The arc furnace is evacuated to a vacuum of 3 Pa, the DC arc discharge current is set to 50 A, and the furnace is filled with 40 KPa argon gas. Then the arc is started and the discharge time is set to 5 s. The reactants on the inner wall of the reaction chamber are collected as titanium boride particles.

[0038] <Example 4> (1) Manufacturing of discharge anodes A mixture of boron powder and tricobalt tetroxide in a ratio of 10:1 was placed in a mortar to mix the two materials uniformly to obtain a mixture, which was then placed in a hydraulic press to compress into a lump mixture.

[0039] (2) Using the tungsten rod as the cathode and the lump mixture as the anode, the tungsten rod and the lump mixture are placed in an arc furnace with a gap of 1 mm between the electrodes. The arc furnace is evacuated to a vacuum of 3 Pa, the DC arc discharge current is set to 12 A, and the arc is started after filling with 70 KPa argon gas. The discharge time is set to 30 s, and the reactants on the inner wall of the reaction chamber are collected as cobalt boride particles.

[0040] <Example 5> (1) Manufacturing of discharge anodes A mixture of boron powder and triiron tetroxide in a ratio of 10:1 was placed in a mortar to mix the two materials uniformly to obtain a mixture, which was then placed in a hydraulic press to compress into a lump mixture.

[0041] (2) Using the tungsten rod as the cathode and the lump mixture as the anode, the tungsten rod and the lump mixture are placed in an arc furnace with a gap of 1 mm between the electrodes. The arc furnace is evacuated to a vacuum of 3 Pa, the DC arc discharge current is set to 12 A, and the arc is started after filling with 70 KPa argon gas. The discharge time is set to 5 s, and the reactants on the inner wall of the reaction chamber are collected as iron boride particles.

[0042] Further, the transition metal boride prepared in Example 1 is analyzed. FIG. 3 is the X-ray diffraction pattern of the nickel boride particles prepared in Example 1. As shown in the measurement results, the diffraction peak of the product is almost consistent with the standard spectrum below. That is, high-purity nickel boride particles were obtained by the DC arc method in Example 1. Furthermore, FIG. 4 is a transmission electron microscope image of the nickel boride particles prepared in Example 1, and the planar spacing d of the nickel boride particles was measured to be 0.28 nm. This value corresponds to the (110) crystal plane of the nickel boride structure, and it is declared that nickel boride has been successfully prepared.

[0043] Further, the vanadium diboride particles prepared in Example 2 are analyzed. FIG. 5 is the X-ray diffraction pattern of the vanadium diboride particles prepared in Example 2. As shown in the measurement results, the diffraction peak of the product is almost consistent with the standard spectrum below. That is, high-purity vanadium diboride particles were obtained by the DC arc method in Example 2. Furthermore, FIG. 6 is a transmission electron microscope image of the vanadium diboride particles prepared in Example 2, and the planar spacing d of the nickel boride particles was measured to be 0.12 nm. This value corresponds to the (201) crystal plane of the vanadium diboride structure, and it is declared that vanadium diboride has been successfully prepared.

[0044] Further, the titanium diboride particles prepared in Example 3 are analyzed. FIG. 7 is the X-ray diffraction pattern of the titanium diboride particles prepared in Example 3. As shown in the measurement results, the diffraction peak of the product is basically consistent with the standard spectrum below. That is, the DC arc method of Example 3 has produced high-purity titanium diboride particles. Furthermore, FIG. 8 is a transmission electron microscope image of the titanium diboride particles prepared in Example 3, and the planar spacing d of the nickel boride particles is measured to be 0.12 nm. This value corresponds to the (201) crystal plane of the nickel boride structure, proclaiming that titanium diboride has been successfully produced.

[0045] Further, the titanium diboride particles prepared in Example 4 are analyzed. Here, FIG. 9 is the X-ray diffraction pattern of the cobalt boride particles prepared in Example 4. As shown in the detection results, the diffraction peaks of the product are basically consistent with the standard spectrum below. That is, the DC arc method of Example 4 has produced high-purity cobalt boride particles. Furthermore, FIG. 10 is a transmission electron microscope image of the cobalt boride particles prepared in Example 4, and the planar spacing d of the nickel boride particles is measured to be 0.12 nm. This value corresponds to the (111) crystal plane of the nickel boride structure, proclaiming that the cobalt boride has been successfully prepared.

[0046] The above examples are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above examples, and any other changes, modifications, substitutions, combinations, and simplifications made without departing from the spirit and principles of the present invention are all included in the protection scope of the present invention.

Claims

1. Providing a tungsten rod and a bulk mixture of boron powder and metal oxide, and placing the tungsten rod and the bulk mixture as an anode and a cathode, respectively, in an arc furnace; and then evacuating the arc furnace, filling it with a buffer gas, controlling the arc furnace to start an arc, igniting the lumpy mixture, and immediately controlling the arc furnace to close the arc, thereby causing a continuous combustion reaction of the lumpy mixture to obtain transition metal borides.

2. 2. The method for rapid synthesis of transition metal borides according to claim 1, wherein the buffer gas is argon gas.

3. 2. The method for rapid synthesis of transition metal borides according to claim 1, wherein the metal oxide is one of tricobalt tetroxide, triiron tetroxide, high nickel oxide, titanium dioxide, and vanadium dioxide.

4. 2. The method for rapidly producing transition metal borides according to claim 1, wherein the gap between the bulk mixture and the tungsten rod in the arc furnace is 1 to 3 mm.

5. 2. The method for rapidly producing transition metal borides according to claim 1, wherein the discharge current of the arc is 12 to 50 A, and the discharge time of the arc is 1 to 30 s.

6. 2. The method for rapidly producing a transition metal boride according to claim 1, wherein the degree of vacuum after evacuation of the arc furnace is 3 Pa or less.

7. 3. The method for rapidly producing transition metal borides according to claim 2, wherein the pressure of the argon gas is 40 to 80 KPa.

8. 2. The method of claim 1, wherein the transition metal boride comprises one of nickel boride, cobalt boride, vanadium diboride, and titanium diboride.

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