Preparation method of large-size titanium diboride powder

Abstract

The application provides a preparation method of large-size titanium diboride powder and belongs to the technical field of titanium diboride powder; the preparation method comprises the steps of modifying titanium dioxide, pretreating carbon black and mixing and sintering; in the step of modifying titanium dioxide, boric acid and lithium carbonate are added into an ethanol solution, then titanium dioxide is added, ultrasonic dispersion is carried out, and coated titanium dioxide is obtained; the coated titanium dioxide is added into a niobium nitrate solution, stirring is carried out at room temperature for 20-30 min, after drying, the modified titanium dioxide is obtained by keeping the temperature at 580-600 DEG C for 110-120 min; the titanium diboride powder prepared by the method has uniform size distribution, high purity and good stability.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of titanium diboride powder, and particularly relates to a preparation method of large-size titanium diboride powder. BACKGROUND

[0002] Titanium diboride is an ultra-hard ceramic material with a hexagonal crystal structure, and has a high melting point of 3225 DEG C, high hardness, excellent high-temperature resistance, wear resistance and corrosion resistance, good electrical conductivity and thermal conductivity, and excellent thermal shock resistance, and can maintain structural stability at high temperatures.

[0003] Based on the above properties, titanium diboride powder has an irreplaceable role in many fields; in the field of super-hard materials, titanium diboride can be used as a reinforcing phase or matrix material for tools and molds, and is used for processing high-hardness alloys, ceramics and other difficult-to-machine materials; in the field of high-temperature structural materials, it can be used to prepare high-temperature components and high-temperature crucibles for the metallurgical industry; in the field of electrode materials, it can be used for aluminum electrolysis cathodes and molten salt electrolysis electrodes, and can extend the service life of the electrodes due to its high electrical conductivity and corrosion resistance; in the field of composite materials, titanium diboride can be used as a reinforcing phase for metal-based and ceramic-based composite materials to improve the strength, hardness and high-temperature resistance of the composite materials; titanium diboride can also be used in the field of protective materials to prepare bulletproof armor layers and the like, and can achieve efficient protection due to its high hardness and radiation resistance.

[0004] However, existing titanium diboride powders are mostly nanoscale or microscale, and when preparing composite materials, the specific surface area of small-size powders is large, the surface activity is high, and the powders are easy to agglomerate during the forming process, and are not uniformly dispersed in the matrix, so that a uniform reinforcing network cannot be formed, which causes defects such as pores and cracks in the sintered body, and thus the composite material is easy to break at the interface when subjected to stress, which reduces the density and mechanical properties of the composite material, and the reinforcing effect of titanium diboride cannot be fully utilized; large-size titanium diboride powders with regular morphology can construct a more stable skeleton structure, reduce the number of grain boundaries, and are more conducive to ensuring the structural integrity and performance stability of the material, thereby improving the fracture toughness, electrical conductivity and thermal conductivity, and high-temperature stability of the composite material.

[0005] Therefore, it is of great significance to prepare large-size titanium diboride powders.

[0006] The prior art usually adopts carbon thermal reduction method and molten salt assisted method when preparing large-size titanium diboride powder; wherein, the reaction temperature of the carbon thermal reduction method is high, the energy consumption is large, the period is long, the grain growth is disordered, the size distribution is wide, and the product purity is not high; the molten salt assisted method is to carry out the reaction in a salt medium, which can reduce the reaction temperature, promote the crystal growth and morphology aggregation, but the solubility of the reactants in the molten salt system is limited, and the anisotropic growth of the crystals in the reaction system is obvious, so it is difficult to obtain uniform large-size titanium diboride powder.

[0007] Therefore, it is a technical problem to be solved by the prior art to provide a preparation method of large-size titanium diboride powder, which can accurately control the size of titanium diboride powder, has uniform size distribution, and has high product purity. SUMMARY

[0008] In order to solve the technical problems existing in the prior art, the present application provides a preparation method of large-size titanium diboride powder, which can accurately control the size of titanium diboride crystals, and the obtained product has uniform size distribution and high purity.

[0009] In view of the above technical problems, the present application adopts the following technical solutions:

[0010] A preparation method of large-size titanium diboride powder, comprising the steps of modifying titanium dioxide, carbon black pretreatment and mixing sintering, and the specific operation is as follows:

[0011] 1. Modified titanium dioxide

[0012] Boric acid, lithium carbonate are added to the ethanol solution, stirred at 500-560 rpm for 35-40 min, then titanium dioxide is added, ultrasonic dispersion is carried out, the ultrasonic time is 1.5-2.0 h, the ultrasonic power is 210-220 W, the ultrasonic frequency is 32-36 kHz, after ultrasonic dispersion, vacuum drying is carried out at 110-120℃ for 4.0-5.0 h, coated titanium dioxide is obtained; the coated titanium dioxide is added to the niobium nitrate solution, stirred at room temperature for 20-30 min, the stirring speed is 400-450 rpm, after drying, calcination is carried out, the temperature is increased to 580-600℃ at a rate of 3.0-4.0℃ / min, and the temperature is kept for 110-120 min, the calcination atmosphere is argon, after calcination, the temperature is naturally cooled to room temperature, and modified titanium dioxide is obtained;

[0013] The mass ratio of the ethanol solution, boric acid, lithium carbonate and titanium dioxide is 300:3.5-3.7:2.0-2.4:50-54;

[0014] The volume concentration of the ethanol solution is 62-67%;

[0015] The mass ratio of the coated titanium dioxide and niobium nitrate solution is 13-15:20-25;

[0016] The niobium nitrate solution is a mixture of niobium nitrate and deionized water, wherein the mass ratio of niobium nitrate to deionized water is 0.18-0.20:20.

[0017] 2. Carbon black pretreatment

[0018] Carbon black and urea were ball-milled in a ball mill with a ball-to-material ratio of 3-5:1, a milling speed of 250-300 rpm, and a milling time of 1.8-2.2 h. After milling, the temperature was increased to 800-820 °C at a rate of 3.0-4.0 °C / min under a nitrogen atmosphere and calcined for 2.5-3.0 h. After calcination, the mixture was allowed to cool naturally to room temperature and then added to a potassium hydroxide solution. The mixture was stirred at 46-50 °C for 60-80 min, dried, and then calcined at 840-850 °C for 2.0-2.3 h under an argon atmosphere. After washing and drying, pretreated carbon black was obtained.

[0019] The mass ratio of carbon black, urea, and potassium hydroxide solution is 10-12:28-33:55-60;

[0020] The mass concentration of the potassium hydroxide solution is 25-30.

[0021] 3. Mixed sintering

[0022] Modified titanium dioxide, boron carbide, pretreated carbon black, and additives were mixed and added to deionized water. After stirring evenly, the mixture was spray-dried, with the inlet temperature controlled at 210-220℃, the outlet temperature at 100-105℃, and the centrifugal speed at 8000-10000 rpm. Then, the mixture was sintered under an argon atmosphere, with the temperature increased to 1250-1300℃ at a rate of 3.0-4.0℃ / min and held for 2.5-3.0 h. Then, the temperature was increased to 1880-1920℃ at a rate of 1.5-2.0℃ / min and held for 7.0-8.0 h. After naturally cooling to room temperature, the mixture was treated by air jet milling to obtain TiB2 crystals with D50=30-50μm.

[0023] The mass ratio of the modified titanium dioxide, boron carbide, pretreated carbon black, and deionized water is 32-37:38-42:22-26:500.

[0024] The auxiliary agent is one of auxiliary agent one or auxiliary agent two;

[0025] The first additive is titanium diboride; the second additive is at least one of zirconium oxide, yttrium oxide, and niobium oxide.

[0026] The mass ratio of the modified titanium dioxide to the first additive is 32-37:5.0-5.25;

[0027] The mass ratio of the modified titanium dioxide to the second additive is 32-37:0.30.

[0028] This invention uses anatase titanium dioxide as the titanium source, carbon black as the carbon source, and boron carbide as the boron source. First, the titanium dioxide is modified. Boric acid and lithium carbonate react in an ethanol solution to generate a LiBO2 sol. During ultrasonic dispersion, the sol uniformly coats the titanium dioxide surface through electrostatic adsorption and hydrogen bonding. Nb in the niobium nitrate solution... 5+ On the adsorption and coating surface, LiBO2, with its low melting point, melts into a liquid phase during high-temperature calcination. This liquid phase acts as a high-speed mass transfer channel, accelerating the diffusion of reactants between titanium dioxide, boron carbide, and carbon black, resulting in a faster and more uniform reaction, reducing impurity formation, and Nb... 5+ This process can guide the growth of titanium diboride grains along dominant crystal planes, avoiding disordered agglomeration and improving product purity. In the carbon black pretreatment step, urea is used to dope the carbon black. After high-temperature calcination, nitrogen atoms diffuse into the carbon black lattice, introducing more reactive sites. Potassium hydroxide etches the carbon black, generating a large number of pores and defects, which increases the contact area between the carbon source and the reactants, thereby enhancing the reducing ability of the carbon black, promoting the reaction, reducing residual carbon, reducing product impurities, and enhancing the high-temperature stability of the carbon black. This ensures the continuous and stable progress of the reduction reaction, allowing the titanium diboride grains to grow synchronously, and ensuring the stability and dimensional uniformity of the titanium diboride product.

[0029] Compared with the prior art, the present invention has achieved the following beneficial effects:

[0030] 1. The large-size titanium diboride powder prepared by the method of the present invention has a purity of 99.2-99.5%;

[0031] 2. The large-size titanium diboride powder prepared by the preparation method of the present invention, as analyzed by XRD pattern, has a (001) crystal plane area of ​​323015-600738, a (002) crystal plane area of ​​169305-299576, a total area of ​​2303465-5471700, and the ratio of (001) and (002) crystal plane areas is 14.986-21.373%. Attached Figure Description

[0032] Figure 1 This is a 1000x SEM image of the large-size titanium diboride powder obtained in Example 3.

[0033] Figure 2 The image shows a 700x SEM image of the large-sized titanium diboride powder prepared in Comparative Example 3-1.

[0034] Figure 3 The images show the XRD patterns of large-size titanium diboride powders prepared in Examples 1-3, Comparative Examples 3-1, and Comparative Examples 3-2. Detailed Implementation

[0035] To provide a clearer understanding of the technical features, objectives, and effects of the present invention, specific embodiments of the present invention are now described.

[0036] Example 1

[0037] 1. Modified titanium dioxide

[0038] Add 3.7g boric acid and 2.4g lithium carbonate to 300g ethanol solution, stir at 560rpm for 40min, then add 54g titanium dioxide and ultrasonically disperse for 2.0h, ultrasonic power 220W, ultrasonic frequency 36kHz. After ultrasonic dispersion, vacuum dry at 120℃ for 5.0h to obtain coated titanium dioxide. Add 15g coated titanium dioxide to 25g niobium nitrate solution, stir at room temperature for 30min at 450rpm, dry and then calcine. Increase the temperature to 600℃ at a rate of 4.0℃ / min and hold for 120min in an argon atmosphere. After calcine, cool naturally to room temperature to obtain modified titanium dioxide.

[0039] The volume concentration of the ethanol solution is 67%.

[0040] The niobium nitrate solution is a mixture of niobium nitrate and deionized water, with a mass ratio of niobium nitrate to deionized water of 0.18:20.

[0041] 2. Carbon black pretreatment

[0042] 12g of carbon black and 33g of urea were placed in a ball mill and ball-to-material ratio of 5:1. The ball milling speed was 300 rpm and the ball milling time was 2.2h. After ball milling, the temperature was increased to 820℃ at a rate of 4.0℃ / min under a nitrogen atmosphere and calcined at this temperature for 3.0h. After calcination, the mixture was allowed to cool naturally to room temperature and then added to 60g of 30wt% potassium hydroxide solution. The mixture was stirred at 50℃ for 80min and dried. After drying, the mixture was calcined under an argon atmosphere and calcined at 850℃ for 2.3h. After washing and drying, pretreated carbon black was obtained.

[0043] 3. Mixed sintering

[0044] 37g of modified titanium dioxide, 42g of boron carbide, 26g of pretreated carbon black and 5.25g of titanium diboride were mixed and added to 500g of deionized water. After stirring evenly, the mixture was spray-dried, with the inlet temperature controlled at 220℃, the outlet temperature at 105℃, and the centrifugation speed at 10000rpm. Then, the mixture was sintered under an argon atmosphere, with the temperature increased to 1300℃ at a rate of 4.0℃ / min and held for 3.0h. Then, the temperature was increased to 1920℃ at a rate of 2.0℃ / min and held for 8.0h. After naturally cooling to room temperature, the mixture was treated by air jet milling to obtain TiB2 powder with D50=50μm.

[0045] Example 2

[0046] 1. Modified titanium dioxide

[0047] Add 3.5g boric acid and 2.0g lithium carbonate to 300g ethanol solution, stir at 500rpm for 35min, then add 50g titanium dioxide and ultrasonically disperse for 1.5h, ultrasonic power 210W, ultrasonic frequency 32kHz. After ultrasonic dispersion, vacuum dry at 110℃ for 4.0h to obtain coated titanium dioxide. Add 13g coated titanium dioxide to 20g niobium nitrate solution, stir at room temperature for 20min at 400rpm, dry and then calcine. Increase the temperature to 580℃ at a rate of 3.0℃ / min and hold for 110min in an argon atmosphere. After calcination, cool naturally to room temperature to obtain modified titanium dioxide.

[0048] The volume concentration of the ethanol solution is 62%;

[0049] The niobium nitrate solution is a mixture of niobium nitrate and deionized water, with a mass ratio of niobium nitrate to deionized water of 0.20:20.

[0050] 2. Carbon black pretreatment

[0051] 10g of carbon black and 28g of urea were placed in a ball mill and ball-to-material ratio of 3:1. The ball milling speed was 250 rpm and the ball milling time was 1.8h. After ball milling, the temperature was increased to 800℃ at a rate of 3.0℃ / min under a nitrogen atmosphere and calcined at this temperature for 2.5h. After calcination, the mixture was allowed to cool naturally to room temperature and then added to 55g of 25wt% potassium hydroxide solution. The mixture was stirred at 46℃ for 60min and dried. After drying, the mixture was calcined under an argon atmosphere and calcined at 840℃ for 2.0h. After washing and drying, pretreated carbon black was obtained.

[0052] 3. Mixed sintering

[0053] 32g of modified titanium dioxide, 38g of boron carbide, 22g of pretreated carbon black and 0.30g of additives were mixed and added to 500g of deionized water. After stirring evenly, the mixture was spray-dried, with the inlet temperature controlled at 210℃, the outlet temperature at 100℃, and the centrifugal speed at 8000rpm. Then, the mixture was sintered under an argon atmosphere, with the temperature increased to 1250℃ at a rate of 3.0℃ / min and held for 2.5h. Then, the temperature was increased to 1880℃ at a rate of 1.5℃ / min and held for 7.0h. After naturally cooling to room temperature, the mixture was treated by an air jet mill to obtain TiB2 powder with D50=30μm.

[0054] The additive is a mixture of zirconium oxide, niobium oxide, and yttrium oxide, wherein the mass ratio of zirconium oxide, niobium oxide, and yttrium oxide is 1:1:1.

[0055] Example 3

[0056] 1. Modified titanium dioxide

[0057] Add 3.6g boric acid and 2.2g lithium carbonate to 300g ethanol solution, stir at 530rpm for 37min, then add 52g titanium dioxide and ultrasonically disperse for 1.8h, ultrasonic power 215W, ultrasonic frequency 34kHz. After ultrasonic dispersion, vacuum dry at 115℃ for 4.5h to obtain coated titanium dioxide. Add 14g coated titanium dioxide to 23g niobium nitrate solution, stir at room temperature for 25min at 430rpm, dry and then calcine. Increase the temperature to 590℃ at a rate of 3.5℃ / min and hold for 115min in an argon atmosphere. After calcination, allow to cool naturally to room temperature to obtain modified titanium dioxide.

[0058] The volume concentration of the ethanol solution is 63%;

[0059] The niobium nitrate solution is a mixture of niobium nitrate and deionized water, with a mass ratio of niobium nitrate to deionized water of 0.18:20.

[0060] 2. Carbon black pretreatment

[0061] 11g of carbon black and 30g of urea were placed in a ball mill and ball-to-material ratio of 4:1. The ball milling speed was 280 rpm and the ball milling time was 2.0h. After ball milling, the temperature was increased to 810℃ at a rate of 3.5℃ / min under a nitrogen atmosphere and calcined at this temperature for 2.8h. After calcination, the mixture was allowed to cool naturally to room temperature and then added to 58g of 27wt% potassium hydroxide solution. The mixture was stirred at 48℃ for 70min and dried. After drying, the mixture was calcined under an argon atmosphere and calcined at 845℃ for 2.2h. After washing and drying, pretreated carbon black was obtained.

[0062] 3. Mixed sintering

[0063] 35g of modified titanium dioxide, 40g of boron carbide, 24g of pretreated carbon black and 5.0g of titanium diboride were mixed and added to 500g of deionized water. After stirring evenly, the mixture was spray-dried, with the inlet temperature controlled at 215℃, the outlet temperature at 103℃, and the centrifugal speed at 9000rpm. Then, the mixture was sintered under an argon atmosphere, with the temperature increased to 1280℃ at a rate of 3.5℃ / min and held for 2.8h. Then, the temperature was increased to 1900℃ at a rate of 1.7℃ / min and held for 7.5h. After naturally cooling to room temperature, the mixture was treated by air jet milling to obtain TiB2 powder with D50=40μm.

[0064] The SEM image of the large-size titanium diboride powder prepared in Example 3 at 1000x magnification is shown in the attached figure in the instruction manual. Figure 1 .

[0065] Comparative Example 3-1

[0066] Based on Example 3, the following changes were made:

[0067] The modified titanium dioxide step is omitted; in the mixing and sintering step, the modified titanium dioxide is replaced in equal amounts with untreated titanium dioxide;

[0068] The remaining operations are exactly the same as in Example 3.

[0069] The SEM image of the large-sized titanium diboride powder prepared in Comparative Example 3-1 at 700x magnification is shown in the attached figure in the instruction manual. Figure 2 .

[0070] Comparative Example 3-2

[0071] Based on Example 3, the following changes were made:

[0072] The carbon black pretreatment step is omitted, and in the mixing and sintering step, the pretreated carbon black is replaced with an equal amount of untreated carbon black.

[0073] The remaining operations are exactly the same as in Example 3.

[0074] Performance testing

[0075] 1. Purity

[0076] The purity of the titanium diboride powders prepared in Examples 1-3, Comparative Example 3-1, and Comparative Example 3-2 was tested, and the results are as follows:

[0077]

[0078] 2. Grain orientation

[0079] XRD tests were performed on the titanium diboride powders prepared in Examples 1-3, Comparative Examples 3-1, and 3-2. The XRD patterns are shown in the attached figures in the instruction manual. Figure 3 The XRD diffraction peaks were integrated, and the proportions of the sum of the areas of (001) and (002) peaks were calculated. The results are as follows:

[0080]

[0081] The above results show that the sum of the area ratios of the (001) and (002) crystal planes in Examples 1-3 is greater than 14%, confirming that the precursor modification process effectively induced highly ordered growth of titanium diboride grains along the c-axis, forming a preferred orientation of the (001) crystal plane family. In contrast, Comparative Example 3-1, due to the omission of titanium dioxide modification treatment, directly used untreated titanium dioxide as the titanium source, resulting in disordered growth of titanium diboride grains, accompanied by impurity phase encapsulation and random stacking, which seriously hindered the orientation growth of crystals along the c-axis. In Comparative Example 3-2, due to the omission of carbon black pretreatment, residual carbon and other impurities were distributed in the gaps between titanium diboride grains, hindering mass transport, and thus causing abnormal grain growth and orientation disorder due to uneven mass transfer.

[0082] Unless otherwise specified, all proportions mentioned in this invention are mass proportions, and all percentages are mass percentages.

[0083] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention 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 the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing large-size titanium diboride powder, characterized in that, This includes modified titanium dioxide, carbon black pretreatment, and mixing and sintering steps; The modified titanium dioxide step is as follows: boric acid and lithium carbonate are added to an ethanol solution, and then titanium dioxide is added and ultrasonically dispersed to obtain coated titanium dioxide. Add the coated titanium dioxide to the niobium nitrate solution, stir at room temperature for 20-30 min, dry, and then calcine at 580-600℃ for 110-120 min to obtain modified titanium dioxide. The mass ratio of the ethanol solution, boric acid, lithium carbonate, and titanium dioxide is 300:3.5-3.7:2.0-2.4:50-54. The carbon black pretreatment step is as follows: carbon black and urea are placed in a ball mill for ball milling, and then calcined at 800-820℃ for 2.5-3.0h under a nitrogen atmosphere. Then, carbon black is added to a potassium hydroxide solution, stirred at 46-50℃ for 60-80min, and calcined at 840-850℃ for 2.0-2.3h to obtain pretreated carbon black. The mixed sintering step involves mixing modified titanium dioxide, boron carbide, pretreated carbon black, and additives, adding them to deionized water, stirring until homogeneous, spray drying, sintering under an argon atmosphere, naturally cooling to room temperature, and then processing with an air jet mill to obtain TiB2 crystals with D50=30-50μm.

2. The method for preparing large-size titanium diboride powder according to claim 1, characterized in that, In the modified titanium dioxide step, the volume concentration of the ethanol solution is 62-67%. The titanium dioxide is anatase titanium dioxide.

3. The method for preparing large-size titanium diboride powder according to claim 1, characterized in that, In the modified titanium dioxide step, the mass ratio of the coated titanium dioxide to the niobium nitrate solution is 13-15:20-25; The niobium nitrate solution is a mixture of niobium nitrate and deionized water, wherein the mass ratio of niobium nitrate to deionized water is 0.18-0.20:

20.

4. The method for preparing large-size titanium diboride powder according to claim 1, characterized in that, In the carbon black pretreatment step, the mass ratio of carbon black, urea, and potassium hydroxide solution is 10-12:28-33:55-60. The mass concentration of the potassium hydroxide solution is 25-30%.

5. The method for preparing large-size titanium diboride powder according to claim 1, characterized in that, The mixing and sintering step involves mixing modified titanium dioxide, boron carbide, pretreated carbon black, and additives, adding them to deionized water, stirring until homogeneous, and then spray drying. The inlet temperature is controlled at 210-220℃, the outlet temperature at 100-105℃, and the centrifugal speed at 8000-10000 rpm. Sintering is then carried out under an argon atmosphere, with the temperature increased to 1250-1300℃ at a rate of 3.0-4.0℃ / min and held for 2.5-3.0 h. The temperature is then increased to 1880-1920℃ at a rate of 1.5-2.0℃ / min and held for 7.0-8.0 h. After natural cooling to room temperature, the mixture is treated by air jet milling to obtain TiB2 crystals with D50=30-50μm.

6. The method for preparing large-size titanium diboride powder according to claim 5, characterized in that, The mass ratio of the modified titanium dioxide, boron carbide, pretreated carbon black, and deionized water is 32-37:38-42:22-26:

500.

7. The method for preparing large-size titanium diboride powder according to claim 1, characterized in that, The auxiliary agent is one of auxiliary agent one or auxiliary agent two; The first additive is titanium diboride; the second additive is at least one of zirconium oxide, yttrium oxide, and niobium oxide. The mass ratio of the modified titanium dioxide to the first additive is 32-37:5.0-5.25; The mass ratio of the modified titanium dioxide to the second additive is 32-37:0.30.

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