High-purity titanium diboride powder and method for preparing the same

Abstract

The application belongs to the technical field of metal boride materials, and specifically provides high-purity titanium diboride powder and a preparation method thereof, characterized by comprising the following steps: S01. taking TiH2 coarse powder, crushing to obtain TiH2 fine powder; S02. taking NaBH4 coarse powder, crushing to obtain NaBH4 fine powder; S03. taking the TiH2 fine powder and the NaBH4 fine powder, mixing and ball milling, then briquetting, placing, then passing nitrogen, and sintering to obtain sintered material; the sintering treatment is to place the compacted material in an atmosphere furnace with a sodium vapor condensation reaction tank to perform stage heating and heat preservation operation; S04. taking the sintered material, performing airflow crushing, sieving and magnetic separation to obtain the titanium diboride powder. The preparation method can reduce production energy consumption and improve the purity of the prepared titanium diboride powder.

Description

Technical Field

[0001] This application belongs to the field of metal boride materials technology, and in particular relates to a high-purity titanium diboride powder and its preparation method. Background Technology

[0002] Titanium diboride is an intermetallic compound that combines the ultra-high melting point (3225℃), high hardness (25-30 GPa), and chemical stability of ceramics with the excellent electrical conductivity of metals (resistivity 14-28 μΩ·cm). Traditional methods for synthesizing titanium diboride include the sol-gel method, carbothermal reduction method, and direct elemental synthesis method. The sol-gel method can synthesize high-purity nanoscale particles at low temperatures, but its high process and raw material costs limit its large-scale production. The carbothermal reduction method is suitable for large-scale production, but requires temperatures exceeding 1600℃, long holding times, large synthesized particles, and significant challenges in subsequent crushing. Furthermore, the high free carbon residue (0.5-2 wt%) limits its application in high-end fields. The direct synthesis method using titanium and boron powder avoids the introduction of additional carbon, but boron raw material costs are high, and the synthesis reaction is highly exothermic. This method also results in large particle sizes, significant challenges in subsequent crushing, and poor overall economic efficiency.

[0003] Patent application CN117383577A discloses a process for preparing high-purity titanium diboride powder. The method uses titanium dioxide obtained after calcining metatitanic acid as the titanium source, boron oxide as the boron source, and resin and carbon black as the carbon source. A preform is obtained through stepwise mixing, kneading, extrusion, and curing, followed by sintering and crushing to obtain titanium diboride powder. This method can still be classified as a carbothermal reduction method, which cannot completely avoid free carbon, has a long process time, and carries a high risk of introducing metallic impurities. It does not offer a significant advantage over the most commonly used carbothermal reduction process.

[0004] Patent application CN106631032A discloses a method for preparing high-purity titanium diboride powder. The method uses titanium dioxide as the titanium source, boron carbide as the boron source, and carbon black as the carbon source, supplemented by a polymetallic oxide catalyst. The mixture undergoes a high-temperature carbothermic reduction reaction to obtain titanium diboride. However, this method cannot avoid generating free carbon, and the boron carbide, carbon black, and catalyst contain high levels of impurities that are difficult to completely remove during the process, making it challenging to obtain high-purity titanium diboride.

[0005] Although existing technologies attempt to optimize the process, they still cannot simultaneously meet the four core indicators of low metal impurities, no free carbon, fine particle size, and low energy consumption. Therefore, it is necessary to find a high-purity titanium diboride powder and its preparation method that can reduce energy consumption while improving product purity. Summary of the Invention

[0006] To address the aforementioned issues and further reduce energy consumption while improving product purity, this application provides a high-purity titanium diboride powder and its preparation method.

[0007] This application first provides a method for preparing high-purity titanium diboride powder, including the following steps:

[0008] S01. Take TiH2 coarse powder, crush it to obtain TiH2 fine powder (D50=2-3 micrometers);

[0009] S02. Take coarse NaBH4 powder, crush it to obtain fine NaBH4 powder (D50=6-10 micrometers);

[0010] S03. Take TiH2 fine powder and NaBH4 fine powder, mix them at high speed, then press them into blocks to obtain a green body, place it, then pass nitrogen gas through it and sinter it to obtain a sintered material; the sintering process involves placing the green body in an atmosphere furnace with a sodium vapor condensation reactor for stage heating and heat preservation operations.

[0011] S04. Take the sintered material, and then crush it through airflow, sieve it, and magnetically separate it to obtain the final product;

[0012] In step S03, the molar ratio of TiH2 fine powder to NaBH4 fine powder is 1:(2.1-2.5).

[0013] In step S03, the ball milling speed is set to 1200-1500 rpm for 30-45 minutes.

[0014] In step S03, the molding pressure is controlled to be 2-5 MPa during briquetting.

[0015] By adopting the above technical solution, TiH2, as the titanium source, can be mixed with NaBH4, pressed into blocks, and sintered to obtain high-purity TiB2. This fundamentally avoids residual carbon impurities in the carbothermic reduction path and improves product purity. During the mixing and ball milling stage, titanium elements in the micro-sized TiH2 can be incorporated into the NaBH4 crystal through lattice defects generated by mechanical grinding, forming a new doped crystal structure. This doped crystal reacts in the low-temperature range of the subsequent heating process and is concentratedly converted into the target TiB2 product. The reaction process can be represented by the following reaction formula:

[0016]

[0017]

[0018] The NaH byproduct generated after the reaction decomposes in the high-temperature zone of the stage heating and escapes from the system with the inert gas, thus obtaining high-purity TiB2 sintered material.

[0019] Furthermore, in step S03, the staged heating includes a first-stage heating, a second-stage heating, and a third-stage heating:

[0020] The temperature gradient is set at 5℃ / min for the first stage of heating, raising the room temperature to 420-430℃, and the holding time accounts for 5 / 8 of the total holding time;

[0021] The second stage of heating is set with a temperature gradient of 3℃ / min, and the temperature continues to rise to 725-775℃, with the holding time accounting for 1 / 8 of the total holding time;

[0022] The three-stage heating setting has a temperature gradient of 3℃ / min, and the temperature continues to rise to 1375-1420℃, with the holding time accounting for 1 / 4 of the total holding time.

[0023] By adopting the above technical solution, TiB2 is concentrated in the low-temperature zone of the first stage of heating in the raw material briquettes. The subsequent second stage of heating provides a temperature buffer for the reaction system, avoiding the decomposition and loss of unreacted raw materials due to the sudden rise to high temperature. After the heat preservation treatment of the second stage of heating, the reaction is close to complete. Further raising the temperature to the high-temperature zone can promote the decomposition of reaction by-products and retain the target product TiB2, finally obtaining high-purity titanium diboride sintered material.

[0024] Furthermore, in step S04, the airflow crushing process is set with a compressed airflow of 300-500 m / s, a working fluid pressure of 0.5-0.7 MPa, a feeder frequency of 20-28 Hz, a classifier frequency of 25-32 Hz, and an induced draft fan frequency of 35-40 Hz.

[0025] In step S04, permanent magnets are used for magnetic separation, with a magnetic induction intensity of 12000-50000Gs.

[0026] This application also provides a high-purity titanium diboride powder, which is prepared by the above-described preparation method.

[0027] Compared with the prior art, this application has the following beneficial effects:

[0028] 1. This application provides a raw material process for preparing high-purity titanium diboride. By using TiH2 and NaBH4 through ball milling, briquetting, and sintering, a low-impurity, high-purity TiB2 product can be obtained. This process can fundamentally avoid carbon residue in the traditional carbothermal reduction method and simplify the impurity removal operation.

[0029] 2. This application uses staged heating and heat preservation to sinter the raw material briquettes; in the first stage of heating at low temperature, the Ti and B doped crystals in the molding material react and concentrate to form TiB2. After the second stage of heating buffer, the third stage of heating can remove the reaction byproducts. While purifying TiB2, it avoids the reaction material from being continuously heated in the high-temperature zone, which would lead to an increase in energy consumption.

[0030] 3. The preparation method of this application can yield a high-purity (≥99.5%), free carbon-free, low-metal impurity (Fe≤52.2ppm, Zn≤3.5ppm, Cu≤5.4ppm) micron-sized titanium diboride powder. Attached Figure Description

[0031] Figure 1 The results of SEM (Scanning Electron Microscopy) testing of the high-purity titanium diboride powder prepared according to Example 1 of this application are shown.

[0032] Figure 2 The X-ray diffraction test results are for the high-purity titanium diboride powder prepared according to Example 1 of this application. Detailed Implementation

[0033] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0034] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0035] When using “including,” “having,” and “contains” as described herein, the intention is to cover non-exclusive inclusion, unless an explicit qualifying term such as “only,” “consisting of,” etc., is used, in which case another component may be added.

[0036] The terms "preferred," "more preferably," "better," and "even better" used in this application refer to embodiments of this application that provide certain beneficial effects under certain circumstances. However, other embodiments may also be preferred under the same or other circumstances. Furthermore, the description of one or more preferred embodiments does not imply that other embodiments are unavailable, nor is it intended to exclude other embodiments from the scope of this application. That is, in this application, "preferred," "more preferably," "better," and "even better" are merely descriptions of implementations or embodiments with better effects, but do not constitute a limitation on the scope of protection of this application.

[0037] In this application, terms such as "further," "even more," and "particularly" are used for descriptive purposes and indicate differences in content, but should not be construed as limiting the scope of protection of this application.

[0038] In this application, "at least one" means one or more, such as one, two, or more. "Multiple" or "several" means at least two, such as two, three, etc., and "multi-layered" means at least two layers, such as two layers, three layers, etc., unless otherwise explicitly specified. In the description of this application, "several" means at least one, such as one, two, etc., unless otherwise explicitly specified.

[0039] When a numerical range is disclosed herein, the range is considered continuous and includes the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Furthermore, when the range refers to integers, it includes every integer between the minimum and maximum values ​​of the range. Additionally, when multiple ranges are provided to describe a feature or characteristic, the ranges may be combined. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges to which they are incorporated.

[0040] Unless otherwise specified, all steps in this application may be performed sequentially or randomly. For example, the method comprising steps (a) and (b) indicates that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the mention that the method may also include step (c) indicates that step (c) may be added to the method in any order; for example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc. Unless otherwise stated, singular terms may include plural forms and should not be construed as having a quantity of one.

[0041] In this application, "above" or "below" includes the number itself. For example, "below 1" includes 1.

[0042] In this application, room temperature refers to 0~40℃, including but not limited to 10~40℃, or further to 20~30℃.

[0043] The present application will be further illustrated by the following examples, but these examples do not limit the scope of the present application.

[0044] When numerical ranges are given in the embodiments, it should be understood that, unless otherwise stated in this application, both endpoints of each numerical range and any value between the two endpoints may be selected. Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. All reagents or instruments whose manufacturers are not specified are conventional products that can be purchased commercially. In addition to the specific methods, equipment, and materials used in the embodiments, based on the knowledge of the prior art possessed by one of ordinary skill in the art and the description in this application, any prior art methods, equipment, and materials similar to or equivalent to those described, used, or made by the methods, equipment, and materials in the embodiments of this application may be used to implement this application.

[0045] Example 1

[0046] Coarse TiH2 powder was dried overnight in a blower dryer, and then mechanically crushed to obtain fine TiH2 powder (D50 = 2 μm, D90 = 4.5 μm). Coarse NaBH4 powder was similarly mechanically crushed to obtain fine NaBH4 powder (D50 = 6 μm, D90 = 11.2 μm). The TiH2 and NaBH4 powders were then initially mixed at a molar ratio of 1:2.1. The mixture was then transferred to a ball mill at 1200 rpm and mixed for 30 minutes to obtain a final mixture. This mixture was then added to a biaxial press die and subjected to a pressure of 2 MPa to obtain a 60 mm diameter die. 60mm 20mm square molding materials were left to stand overnight, then transferred to a high-purity graphite crucible and pushed into an atmosphere furnace with a sodium vapor condenser. The furnace was evacuated to below 100 Pa and then stopped. Argon gas was then introduced to atmospheric pressure, followed by heating. The heating curve was as follows: room temperature to 420℃, 5℃ / min, followed by a holding time of 7.5h; 420℃ to 725℃, 3℃ / min, followed by a holding time of 1.5h; 725℃ to 1375℃, 3℃ / min, followed by a holding time of 3h. The material was then allowed to cool naturally to room temperature to obtain the sintered material. The argon gas flow rate was maintained at 10L / min throughout the heating and cooling processes.

[0047] The sintered material was placed in an ultra-high pressure airflow crusher, with the compressed airflow set at 300 m / s, working fluid pressure at 0.5 MPa, feeder frequency at 20 Hz, classifier frequency at 25 Hz, and induced draft fan frequency at 35 Hz. After crushing for 1 hour, the material was passed through a 325-mesh sieve. The residue was then magnetically separated by a permanent magnet (B=12000 Gs) to obtain high-purity titanium diboride powder. Scanning electron microscopy results are shown below. Figure 1 As shown.

[0048] Example 1: XRD diffraction test results of titanium diboride powder are as follows Figure 2As shown, the XRD pattern of the prepared titanium diboride powder completely matches the main diffraction peaks of the standard card PDF#35-0741, confirming that the target product has only titanium diboride peaks and no other impurity peaks or phases.

[0049] Example 2

[0050] Coarse TiH2 powder was dried overnight in a blower dryer, and then mechanically ground to obtain fine TiH2 powder (D50 = 2.3 μm, D90 = 4.7 μm). Coarse NaBH4 powder was similarly mechanically ground to obtain fine NaBH4 powder (D50 = 7.1 μm, D90 = 11.5 μm). The TiH2 and NaBH4 powders were then initially mixed at a molar ratio of 1:2.3. The mixture was then transferred to a ball mill at 1450 rpm for 40 minutes to obtain a final mixture. This mixture was then added to a biaxial press die and subjected to a pressure of 3.2 MPa to obtain a 60 mm diameter die. 60mm A 20mm square molding material was left to stand overnight. The material was then transferred to a high-purity graphite crucible and pushed into an atmosphere furnace equipped with a sodium vapor condenser. The furnace was evacuated to below 100 Pa and then stopped. Argon gas was then introduced to atmospheric pressure, followed by heating. The heating curves were as follows: room temperature to 425℃, 5℃ / min, followed by a 9-hour holding period; 425℃ to 750℃, 3℃ / min, followed by a 1.8-hour holding period; 750℃ to 1400℃, 3℃ / min, followed by a 3.6-hour holding period. The material was then allowed to cool naturally back to room temperature. The argon gas flow rate was maintained at 10 L / min throughout the heating and cooling processes.

[0051] The sintered material was placed in an ultra-high pressure airflow crusher, with a compressed airflow of 400 m / s, a working fluid pressure of 0.7 MPa, a feeder frequency of 23 Hz, a classifier wheel frequency of 28 Hz, and an induced draft fan frequency of 40 Hz. After crushing for 1.5 hours, the material was passed through a 325-mesh sieve. The residue was then magnetically separated by a permanent magnet (B=40000 Gs) to obtain high-purity titanium diboride powder.

[0052] Example 3

[0053] Coarse TiH2 powder was dried overnight in a blower dryer, and then mechanically crushed to obtain fine TiH2 powder (D50 = 3 μm, D90 = 5.2 μm). Coarse NaBH4 powder was similarly mechanically crushed to obtain fine NaBH4 powder (D50 = 10 μm, D90 = 13.7 μm). The TiH2 and NaBH4 powders were then initially mixed at a molar ratio of 1:2.5. The mixture was then transferred to a ball mill and milled at 1500 rpm for 45 minutes to obtain a final mixture. This mixture was then added to a biaxial press die and subjected to a pressure of 5 MPa to obtain a 60 mm diameter die. 60mm A 20mm square molding material was left to stand overnight. The material was then transferred to a high-purity graphite crucible and pushed into an atmosphere furnace equipped with a sodium vapor condenser. The furnace was evacuated to below 100 Pa and then stopped. Argon gas was then introduced to atmospheric pressure, followed by heating. The heating curves were as follows: room temperature to 430℃, 5℃ / min, followed by a 10-hour holding period; 430℃ to 775℃, 3℃ / min, followed by a 2-hour holding period; 775℃ to 1420℃, 3℃ / min, followed by a 4-hour holding period. The material was then allowed to cool naturally back to room temperature. The argon gas flow rate was maintained at 10 L / min throughout both the heating and cooling processes.

[0054] The sintered material was placed in an ultra-high pressure airflow crusher, with a compressed airflow of 500 m / s, a working fluid pressure of 0.7 MPa, a feeder frequency of 28 Hz, a classifier wheel frequency of 32 Hz, and an induced draft fan frequency of 40 Hz. After crushing for 2 hours, the material was passed through a 325-mesh sieve. The residue was then magnetically separated by a permanent magnet (B=50000 Gs) to obtain high-purity titanium diboride powder.

[0055] Comparative Example 1

[0056] The only difference between this comparative example and Example 1 is that the preparation steps of the sintering material are as follows:

[0057] The mixture was added to the die of a biaxial press, and a pressure of 3 MPa was applied to obtain a 60 mm diameter die. 60mm A 20mm square molding material was formed, then transferred to a high-purity graphite crucible, and then pushed into an atmosphere furnace with a sodium vapor condensation reactor. The vacuum was evacuated to below 100Pa and then stopped. Argon gas was then introduced to atmospheric pressure, and the temperature was raised. The heating curve used was: room temperature to 425℃, 5℃ / min, then held for 2h; 425℃ to 725℃, 3℃ / min, then held for 7.5h; 725℃ to 1375℃, 3℃ / min, then held for 2h. After that, it was naturally cooled to room temperature to obtain the sintered material.

[0058] The remaining steps are the same as in Example 1.

[0059] Comparative Example 2

[0060] The only difference between this comparative example and Example 1 is that an equimolar amount of elemental boron is used instead of NaBH4 fine powder, and it is pressed and sintered with TiH2 fine powder to obtain sintered material.

[0061] The remaining steps are the same as in Example 1.

[0062] Performance testing

[0063] The product specifications and testing standards of high-purity titanium diboride in Examples 1-3 and Comparative Examples 1-2 are shown in Table 1.

[0064] Table 1. Product indicators and testing standards of high-purity titanium diboride in Examples 1-3 and Comparative Examples 1-2

[0065]

[0066] The test results are shown in Table 2.

[0067] Table 2. Detection results of high-purity titanium diboride powder in Examples 1-3 and Comparative Examples 1-2

[0068]

[0069] Based on Examples 1-3 and Comparative Examples 1-2, and in conjunction with Tables 1 and 2, it can be concluded that the particle size (D90) of titanium diboride powder and its specific surface area show a positive correlation within a certain range. The titanium diboride powder obtained using the example schemes has a finer particle size and a larger specific surface area. When used as an additive in semiconductor boron carbide / silicon carbide ceramics, it can significantly optimize the density, mechanical strength, and overall performance of the components. Regarding the content of metallic impurities, since no elements such as iron, calcium, magnesium, and silicon are introduced in the process, the results of impurity detection may originate from external introduction during mechanical processing, and the content is within the internal control range of this application, not affecting the purity of the product. However, the Na component introduced in the process, from the impurity... In terms of content, both Comparative Examples 1 and 2 showed significant fluctuations compared to the Example schemes. In Comparative Example 1, the Na content reached 120.7 ppm, which was significantly higher than the average level of the Example schemes. This may be due to an imbalance in the temperature rise and holding test parameters during the sintering process, resulting in a sharp increase in the Na impurity content in the product. Combined with the purity test data of Comparative Example 1, this further confirms that the sintering of Comparative Example 1 was incomplete. In contrast, Comparative Example 2 used elemental boron instead of NaBH4, and the Na element was not introduced into the scheme, resulting in a Na content of almost 0. However, judging from the purity data of Comparative Example 2, using elemental boron as the reaction raw material, only a low-purity titanium diboride product was obtained under the conditions of the Comparative Example scheme.

[0070] Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A method for producing high-purity titanium diboride powder, characterized by comprising: The method comprises the following steps: ​ S01. Take TiH2 coarse powder, crush to obtain TiH2 fine powder; the particle size D50 of the TiH2 fine powder is 2-3 microns; S02. Take NaBH4 coarse powder, crush to obtain NaBH4 fine powder; the particle size D50 of the NaBH4 fine powder is 6-10 microns; S03. Take the TiH2 fine powder and the NaBH4 fine powder, mix and ball mill, then press and form to obtain a green body, place, then pass nitrogen, and sinter to obtain a sintered material; the sintering process is carried out in a furnace with a sodium vapor condensation reaction tank; the stage heating comprises one-stage heating, two-stage heating and three-stage heating: the one-stage heating is set at a temperature gradient of 5 ℃ / min, the room temperature is heated to 420-430 ℃, and the holding time accounts for 5 / 8 of the total holding time; the two-stage heating is set at a temperature gradient of 3 ℃ / min, and the heating continues to 725-775 ℃, and the holding time accounts for 1 / 8 of the total holding time; the three-stage heating is set at a temperature gradient of 3 ℃ / min, and the heating continues to 1375-1420 ℃, and the holding time accounts for 1 / 4 of the total holding time; S04. Take the sintered material, and obtain the product after air flow crushing, sieving and magnetic separation.

2. The method of claim 1, wherein the titanium diboride powder has a purity of 99.9% or more. In the step S03, the molar ratio of the TiH2 fine powder to the NaBH4 fine powder is 1:(2.1-2.5).

3. The method of claim 1, wherein the titanium diboride powder has a purity of 99.9% or more. In the step S03, the ball milling is set at a rotation speed of 1200-1500 rpm for 30-45 min.

4. The method of claim 1, wherein the titanium diboride powder has a purity of 99.9% or more. In the step S03, the forming pressure is controlled to be 2-5 MPa.

5. The method of claim 1, wherein the titanium diboride powder has a purity of 99.9% or more. In the step S04, the air flow crushing is set at a compressed air flow of 300-500 m / s, a working medium pressure of 0.5-0.7 MPa, a feeder frequency of 20-28 Hz, a grading wheel frequency of 25-32 Hz, and an air blower frequency of 35-40 Hz.

6. The method of claim 1, wherein the titanium diboride powder has a purity of 99.9% or more. In the step S04, the magnetic separation uses a permanent magnet, and the magnetic induction intensity is 12000-50000 Gs.

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