High-purity superfine titanium diboride and preparation method thereof

Abstract

The invention provides high-purity superfine titanium diboride and a preparation method thereof, and relates to the field of titanium diboride preparation. The method comprises the following steps: mixing boron oxide, titanium hydride, a carbon source, nano rare earth oxide and an organic solvent, and drying to obtain a mixture; in a vacuum environment, performing first roasting on the mixture to obtain a first roasted material; and in an oxygen-containing atmosphere, carrying out second roasting on the first roasting material to obtain the high-purity superfine titanium diboride. In the first roasting process, boron oxide, titanium hydride and a carbon source are completely melted and fully contacted, then further, the carbon source forms a carbon skeleton, the contact area between the melted boron oxide and titanium hydride and the carbon skeleton is further enlarged, liquid-liquid mixing and the increase of the contact area can reduce the reaction kinetic conditions, the reaction temperature is greatly reduced, and the reaction time is greatly shortened. The particle size of the generated titanium diboride is reduced, and the molten boron oxide and titanium hydride react on the porous carbon skeleton in a liquid-liquid form to generate the high-purity superfine titanium diboride.

Description

Technical Field

[0001] This application relates to the field of titanium diboride preparation, and more particularly to a high-purity ultrafine titanium diboride and its preparation method. Background Technology

[0002] Titanium diboride has a wide range of applications, primarily as follows: as an additive incorporated into metal substrates such as aluminum, copper, and iron, it can refine grains and enhance performance; when combined with ceramics such as silicon carbide and alumina, it can significantly improve the mechanical strength and toughness of the material, making it suitable for armor protection; when incorporated into resins, it can be made into safe and efficient PTC heating materials for various household appliances. Furthermore, its excellent electrical conductivity and resistance to metal corrosion make it suitable for electrodes, crucibles, and cathodes in aluminum electrolysis cells, contributing to energy conservation and extending equipment life; it can also be used to manufacture wear-resistant parts such as ceramic knives and molds.

[0003] However, the quality of titanium diboride powder determines the performance of the finished product. Current technologies for preparing ultrafine titanium diboride mainly rely on ball milling and molten salt methods. Ball milling achieves particle size refinement through adjustments to the ball milling process and method, while the molten salt method achieves ultrafine powder preparation through solid-liquid bonding. However, current methods for preparing titanium diboride generally suffer from the drawback of producing powders with large particle sizes.

[0004] Therefore, there is an urgent need to provide a method for preparing ultrafine titanium diboride powder to solve the above problems. Summary of the Invention

[0005] The purpose of this application is to provide a high-purity, ultrafine titanium diboride and its preparation method to solve the above-mentioned problems.

[0006] To achieve the above objectives, the first aspect of this application provides a method for preparing high-purity ultrafine titanium diboride, comprising: Boron oxide, titanium hydride, carbon source, nano-rare earth oxides and organic solvents are mixed and dried to obtain a mixture; The mixture is subjected to a first calcination under vacuum to obtain a first calcined material; Under an oxygen-containing atmosphere, the first calcined material is subjected to a second calcination to obtain high-purity ultrafine titanium diboride.

[0007] Optionally, the carbon source includes phenolic resin.

[0008] Optionally, the nano-rare earth oxide includes one or more of cerium oxide, lanthanum oxide, neodymium oxide, yttrium oxide, and praseodymium oxide.

[0009] Optionally, the organic solvent includes ethanol and / or acetone.

[0010] Optionally, the method for preparing high-purity ultrafine titanium diboride satisfies at least one of the following conditions: (1) The mass ratio of the boron oxide, the titanium hydride, and the carbon source is 1-3:1-3:4-8; (2) The mass ratio of the nano-rare earth oxide to the carbon source is 1-5:40-80.

[0011] Optionally, the mass ratio of boron oxide to titanium hydride is 1:1.

[0012] Optionally, the first calcination includes a third calcination, a fourth calcination, and a fifth calcination performed sequentially; The third roasting temperature is 500-600℃, and the time is 1-2 hours; The fourth roasting temperature is 700-800℃, and the time is 2-4 hours; The fifth roasting temperature is 1200-1400℃, and the time is 2-4 hours.

[0013] Optionally, the method for preparing high-purity ultrafine titanium diboride satisfies at least one of the following conditions: (1) The second roasting temperature is 700-1000℃ and the time is 3-6h; (2) After the second roasting, acid washing, water washing and drying are carried out in sequence.

[0014] The second aspect of this application provides a high-purity ultrafine titanium diboride, which is prepared by the aforementioned method for preparing high-purity ultrafine titanium diboride.

[0015] Optionally, the high-purity ultrafine titanium diboride has a particle size of less than 200 nm and a purity of >99%.

[0016] Compared with the prior art, the beneficial effects of this application include: The method for preparing high-purity ultrafine titanium diboride provided in this application involves the following steps: During the first calcination process, boron oxide, titanium hydride, and a carbon source are completely melted and brought into full contact. Then, the carbon source forms a carbon skeleton, further expanding the contact area between the molten boron oxide and titanium hydride and the carbon skeleton. This liquid-liquid mixing and increased contact area reduce reaction kinetics, significantly lowering the reaction temperature and resulting in a smaller titanium diboride particle size. The molten boron oxide and titanium hydride react in a liquid-liquid form on the porous carbon skeleton to generate high-purity ultrafine titanium diboride. Furthermore, during the synthesis of high-purity ultrafine titanium diboride, nano-rare earth oxides act like "nails" at the grain boundaries of the synthesized titanium diboride particles, restricting grain boundary movement and thus hindering grain merging and growth. High-purity ultrafine titanium diboride.

[0017] The high-purity ultrafine titanium diboride provided in this application has fine particle size and high purity. Attached Figure Description

[0018] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation on the scope of this application.

[0019] Figure 1 The image shows a SEM image of the high-purity ultrafine titanium diboride provided in Example 1. Detailed Implementation

[0020] First, the solution provided in this application will be explained in more detail as follows: The first aspect of this application provides a method for preparing high-purity ultrafine titanium diboride, comprising: Boron oxide, titanium hydride, carbon source, nano-rare earth oxides and organic solvents are mixed and dried to obtain a mixture; In some embodiments, the mixing includes first mixing the boron oxide, the titanium hydride, and the carbon source to obtain a first mixture; second mixing the nano-rare earth oxide and the organic solvent to obtain a second mixture; and third mixing the first mixture and the second mixture, followed by ultrasonication. It should be noted that the titanium source in the prior art (such as metatitanic acid) is solid when reacting at high temperatures, and the reaction to form titanium diboride is essentially a solid-liquid reaction. Solid-liquid reactions lead to high reaction temperatures and larger particle sizes. In contrast, the titanium source (titanium hydride) in this application has a low melting point and is liquid at 450°C. Therefore, the reaction of titanium diboride in this application is essentially a liquid-liquid reaction with uniform mixing. At the same time, the liquid-liquid reaction temperature is lower, and uniform mixing leads to higher reaction purity. The lower reaction temperature leads to finer particle size, which is more conducive to the formation of high-purity and ultrafine titanium diboride. The mixture is subjected to a first calcination under vacuum to obtain a first calcined material; Under an oxygen-containing atmosphere, the first calcined material is subjected to a second calcination to obtain high-purity ultrafine titanium diboride.

[0021] It should be noted that the second roasting can achieve the purpose of high-temperature oxidation and decarburization.

[0022] In some embodiments, the carbon source includes phenolic resin.

[0023] In some embodiments, the nano-rare earth oxide includes one or more of cerium oxide, lanthanum oxide, neodymium oxide, yttrium oxide, and praseodymium oxide.

[0024] In some embodiments, the organic solvent includes ethanol and / or acetone.

[0025] In some embodiments, the method for preparing high-purity ultrafine titanium diboride satisfies at least one of the following conditions: (1) The mass ratio of the boron oxide, the titanium hydride, and the carbon source is 1-3:1-3:4-8; It should be noted that if the mass ratio of carbon source is too low, it cannot provide a sufficient porous carbon framework, which is not conducive to the synthesis of high-purity ultrafine titanium diboride. If the mass ratio is too high, the ratio of boron oxide and titanium hydride will decrease, the amount of titanium diboride synthesized will decrease, and the efficiency will decrease. Optionally, the mass ratio of boron oxide, titanium hydride and carbon source can be any value between 1:1:4, 2:1:4, 3:1:4, 1:2:4, 1:3:4, 2:2:5, 2:3:6, 2:2:7, 2:3:8 or 1-3:1-3:4-8; (2) The mass ratio of the nano-rare earth oxide to the carbon source is 1-5:40-80.

[0026] Optionally, the mass ratio of nano-rare earth oxides to carbon source can be any value between 1:40, 2:40, 3:40, 4:40, 5:40, 1:50, 1:60, 1:70, 1:80, 5:80, or 1-5:40-80.

[0027] It should be noted that if the proportion of nano-rare earth oxides added is too low, it will not be able to refine the product particles or enhance the product dispersibility; if the proportion added is too high, it will lead to waste and increase the preparation cost.

[0028] In some embodiments, the mass ratio of boron oxide to titanium hydride is 1:1.

[0029] It should be noted that the ratio of boron oxide to titanium hydride is 1:1 by mass, which is mainly determined by the reaction ratio. During the reaction, some titanium hydride will be lost. Based on the overall experimental results, the purity obtained by the 1:1 reaction is higher.

[0030] In some embodiments, the first calcination includes a third calcination, a fourth calcination, and a fifth calcination performed sequentially. It is important to note that both boron oxide and titanium hydride have a melting point of 450℃, while phenolic resin has a melting point of around 200℃ and a carbonization temperature of 600℃. Therefore, during the third calcination (500-600℃), the properties of these three substances allow them to be mixed together in liquid form. Then, during the fourth calcination, as the carbon source gradually carbonizes, titanium hydride and boron oxide adhere to the carbonized porous carbon framework in molten form, further expanding the contact area between them and the porous carbon framework (reducing agent). Simultaneously, the nano-rare earth oxides adhere to the porous carbon framework, further promoting the carbothermic reduction reaction and lowering the reaction temperature. With the fifth calcination, the molten titanium hydride and boron oxide react in a liquid-liquid form within the porous carbon framework, directly generating nano-high-purity ultrafine titanium diboride. The carbonization of phenolic resin into porous carbon, while boron oxide and titanium hydride remain in liquid-liquid contact, makes the reaction to produce titanium diboride easier. The third roasting temperature is 500-600℃, and the time is 1-2 hours; Optionally, the temperature of the third sintering can be any value between 500℃, 510℃, 520℃, 530℃, 540℃, 550℃, 560℃, 570℃, 580℃, 590℃, 600℃ or 500-600℃, and the time can be any value between 1h, 1.5h, 2h or 1-2h. It is important to note that the third roasting process melts all the boron oxide, titanium hydride, and carbon source, achieving intermolecular mixing and full contact. This full contact not only allows the carbon source to form a uniform framework after carbonization but also enables subsequent reactions to be more complete, with fewer impurities and higher purity. If the third roasting time is too short, the above raw materials cannot be fully mixed with each other; if the time is too long, it wastes time and consumes too much energy. Time constraints: Too short a time will not allow for sufficient mixing, while too long a time will be a waste of time and energy. The fourth roasting temperature is 700-800℃, and the time is 2-4 hours; Optionally, the temperature of the third sintering can be any value between 700℃, 710℃, 720℃, 730℃, 740℃, 750℃, 760℃, 770℃, 780℃, 790℃, 800℃ or 700-800℃, and the time can be any value between 2h, 3h, 4h or 2-4h. It is important to note that the fourth roasting mainly carbonizes the carbon source, generating a porous carbon framework structure, which further expands the contact area between boron oxide, titanium hydride, and the reducing agent, thus lowering the required reaction temperature (i.e., the temperature of the fifth roasting). If the holding time of the fourth roasting is too short, the porous carbon framework cannot be fully formed; if the time is too long, it wastes time and consumes too much energy. The fifth roasting temperature is 1200-1400℃, and the time is 2-4 hours.

[0031] Optionally, the temperature of the fifth roasting can be any value between 1200℃, 1250℃, 1300℃, 1350℃, 1400℃ or 1200-1400℃, and the time can be any value between 2h, 3h, 4h or 2-4h.

[0032] It is important to note that the fifth calcination mainly involves the molecular-level bonding of boron oxide and titanium hydride on a porous carbon framework in a liquid-liquid form. This reaction occurs over a shorter distance, at a lower temperature, and is more likely to occur, directly precipitating nano-high-purity ultrafine titanium diboride in a liquid-liquid form, resulting in a fine product particle size. However, if the holding time of the fifth calcination is too short, the reaction cannot be fully completed; if the holding time is too long, energy consumption is high, and the particle size will further increase, which is not conducive to the preparation of high-purity ultrafine titanium diboride.

[0033] It is also important to note that during the fifth calcination and holding process for synthesizing high-purity ultrafine titanium diboride, nano-rare earth oxides act like "nails" at the grain boundaries of the synthesized titanium diboride particles, restricting grain boundary movement and thus hindering grain aggregation and growth. Simultaneously, the surface charge of the nano-rare earth oxides prevents the aggregation of primary particles due to van der Waals forces through electrostatic repulsion or steric hindrance, maintaining the dispersed state of the generated small-sized titanium diboride particles. The pinning and steric hindrance effects of the nano-rare earth oxides synergistically interact with the fifth calcination and holding process. The fifth calcination and holding temperature, due to the liquid-liquid reaction occurring on the carbon framework, significantly lowers the reaction temperature, thereby reducing the kinetics for further particle growth. The addition of nano-rare earth oxides, on the one hand, further restricts grain movement and hinders particle growth through the pinning effect, and on the other hand, improves the particle dispersibility of high-purity ultrafine titanium diboride through electrostatic repulsion or steric hindrance. The heating of the nano-rare earth oxides and the fifth calcination and holding synthesis have a very good synergistic effect.

[0034] In some embodiments, the method for preparing high-purity ultrafine titanium diboride satisfies at least one of the following conditions: (1) The second roasting temperature is 700-1000℃ and the time is 3-6h; Optionally, the temperature of the second roasting can be any value between 700℃, 800℃, 900℃, 1000℃ or 700-1000℃, and the time can be any value between 3h, 4h, 5h, 6h or 3-6h. (2) After the second roasting, acid washing, water washing and drying are carried out in sequence.

[0035] It should be noted that acid washing can remove the small amount of Ti and nano-rare earth oxides generated, while water washing can remove the acid residue from the acid washing process.

[0036] In some embodiments, the pickling temperature is ≥80°C.

[0037] The second aspect of this application provides a high-purity ultrafine titanium diboride, which is prepared by the aforementioned method for preparing high-purity ultrafine titanium diboride.

[0038] In some embodiments, the high-purity ultrafine titanium diboride has a particle size of less than 200 nm and a purity of >99%.

[0039] Optionally, the particle size of high-purity ultrafine titanium diboride can be any value of 10nm, 50nm, 100nm, 150nm, 190nm or less than 200nm, and the purity can be any value of 99.1%, 99.9%, 99.99% or greater than 99%.

[0040] The implementation schemes of this application will be described in detail below with reference to specific embodiments. However, those skilled in the art will understand that the following embodiments are only for illustrating this application and should not be regarded as limiting the scope of this application. Unless otherwise specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments used without specified manufacturers are all conventional products that can be purchased commercially.

[0041] Example 1 This embodiment provides a high-purity, ultrafine titanium diboride and its preparation method. The preparation steps are as follows: S1: Boron oxide, titanium hydride and phenolic resin are dried and then mixed evenly by ball milling in a mass ratio of 2:2:6 to serve as the first reaction material. S2: According to the mass ratio of nano-rare earth oxide to carbon source of 3:60, add the corresponding mass of nano-rare earth oxide (lanthanum oxide) to organic solvent (ethanol), and disperse it evenly by ultrasonic stirring, as the second reaction raw material; S3: Add reactant one to reactant two, continue ultrasonic stirring for a certain time, then dry and sieve to obtain reactant three; S4: Place the reaction material three into a graphite crucible and heat it in a vacuum furnace; first, heat it to 550°C and hold it for 2 hours; then, continue heating it to 750°C and hold it for 3 hours; then, heat it to 1300°C and hold it for 3 hours; after the third heating is completed, allow it to cool naturally to room temperature and remove the material. S5: The extracted material is subjected to high-temperature oxidation and decarburization in a muffle furnace (heated to 900℃ and held for 5 hours), then naturally cooled to room temperature, and then acid-washed with 40% sulfuric acid (temperature 90℃) - washed with water (to remove acid), dried, and sieved to obtain the final high-purity ultrafine titanium diboride.

[0042] SEM images of this high-purity, ultrafine titanium diboride are shown below. Figure 1 As shown.

[0043] Example 2 The difference from Example 1 is that in step S1, the mass ratio of boron oxide, titanium hydride, and phenolic resin is 2:2:4.

[0044] Example 3 The difference from Example 1 is that in step S2, the mass ratio of nano-rare earth oxides to carbon source is 3:80.

[0045] Comparative Example 1 The difference from Example 1 is that titanium hydride in step S1 is replaced with metatitanic acid.

[0046] Comparative Example 2 The difference from Example 1 is that no nano-rare earth oxides are added in step S2.

[0047] Comparative Example 3 The difference from Example 1 is that in step S4, the temperature is directly raised to 1400°C in a vacuum furnace without multi-step heating.

[0048] Comparative Example 4 The difference from Example 1 is that in step S1, the mass ratio of boron oxide, titanium hydride, and phenolic resin is 4:5:3.

[0049] Comparative Example 5 The difference from Example 1 is that the mass ratio of nano-rare earth oxides to carbon source is 0.5:90.

[0050] The high-purity ultrafine titanium diboride prepared in the above examples was subjected to particle size and purity tests, and the specific test results are shown in Table 1.

[0051] Table 1. Particle size and purity tests

[0052] analyze: The results above show that when the preparation conditions are within the range of the high-purity ultrafine titanium diboride preparation method provided in this application, high-purity ultrafine titanium diboride with a wavelength of <200 nm and a purity of ≥99% can be obtained.

[0053] Comparing Examples 1 and 2, it can be seen that a decrease in the carbon source ratio is detrimental to the synthesis of titanium boride, resulting in larger particle size and lower purity. Comparing Examples 1 and 3, it can be seen that a decrease in the proportion of nano-rare earth oxides is detrimental to the particle size control of titanium boride, resulting in larger particle size. Comparing Examples 1 and Comparative Example 1, it can be seen that replacing the reaction product with metatitanic acid resulted in coarser product particle size and lower purity. This indicates that titanium hydride, melted into a liquid during preparation, undergoes a liquid-liquid reaction with boron oxide, which contributes to both reducing the particle size and improving the purity of the synthesized product. The addition of nano-rare earth oxides plays an important role in controlling the particle size of the product. Comparing Example 1 and Comparative Example 2, it can be seen that without the addition of nano-rare earth oxides, the product particle size cannot be controlled below 200 nm, indicating that nano-rare earth oxides play a crucial role in controlling the product particle size. Comparing Example 1 and Comparative Example 3, it can be seen that directly heating to the reaction temperature in step S4 results in coarse product particles and reduced purity, demonstrating that segmented heating in the first calcination process plays a crucial role in controlling the particle size and purity of the product. Comparing Example 1 with Comparative Examples 4 and 5, it shows that the ratio of reaction raw materials plays a crucial role in controlling the particle size and purity of the product.

[0054] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

[0055] Furthermore, those skilled in the art will understand that although some embodiments herein include certain features included in other embodiments but not others, combinations of features from different embodiments are intended to be within the scope of this application and form different embodiments. For example, any of the claimed embodiments can be used in any combination. The information disclosed in this background section is intended only to enhance the understanding of the general background of this application and should not be construed as an admission or in any way implying that such information constitutes prior art known to those skilled in the art.

Claims

1. A method for preparing high-purity ultrafine titanium diboride, characterized in that, include: Boron oxide, titanium hydride, carbon source, nano-rare earth oxides and organic solvents are mixed and dried to obtain a mixture; The mixture is subjected to a first calcination under vacuum to obtain a first calcined material; Under an oxygen-containing atmosphere, the first calcined material is subjected to a second calcination to obtain high-purity ultrafine titanium diboride.

2. The method for preparing high-purity ultrafine titanium diboride according to claim 1, characterized in that, The carbon source includes phenolic resin.

3. The method for preparing high-purity ultrafine titanium diboride according to claim 1, characterized in that, The nano-rare earth oxides include one or more of cerium oxide, lanthanum oxide, neodymium oxide, yttrium oxide, and praseodymium oxide.

4. The method for preparing high-purity ultrafine titanium diboride according to claim 1, characterized in that, The organic solvents include ethanol and / or acetone.

5. The method for preparing high-purity ultrafine titanium diboride according to claim 1, characterized in that, At least one of the following conditions must be met: (1) The mass ratio of the boron oxide, the titanium hydride, and the carbon source is 1-3:1-3:4-8; (2) The mass ratio of the nano-rare earth oxide to the carbon source is 1-5:40-80.

6. The method for preparing high-purity ultrafine titanium diboride according to claim 5, characterized in that, The mass ratio of boron oxide to titanium hydride is 1:

1.

7. The method for preparing high-purity ultrafine titanium diboride according to claim 1, characterized in that, The first roasting includes a third roasting, a fourth roasting, and a fifth roasting performed sequentially; The third roasting temperature is 500-600℃, and the time is 1-2 hours; The fourth roasting temperature is 700-800℃, and the time is 2-4 hours; The fifth roasting temperature is 1200-1400℃, and the time is 2-4 hours.

8. The method for preparing high-purity ultrafine titanium diboride according to any one of claims 1-7, characterized in that, At least one of the following conditions must be met: (1) The second roasting temperature is 700-1000℃ and the time is 3-6h; (2) After the second roasting, acid washing, water washing and drying are carried out in sequence.

9. A high-purity, ultrafine titanium diboride, characterized in that, It is prepared by the method for preparing high-purity ultrafine titanium diboride according to any one of claims 1-8.

10. The high-purity ultrafine titanium diboride according to claim 9, characterized in that, The high-purity ultrafine titanium diboride has a particle size of less than 200 nm and a purity of >99%.

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