A method for preparing high-purity TiB2 powder at low temperature and high efficiency

Abstract

The application belongs to the field of ceramic powder preparation, and discloses a method for preparing high-purity TiB2 powder at low temperature and high efficiency. The method comprises the following steps: uniformly mixing a titanium source, a boron source, a reducing agent, an alkaline additive and deionized water / organic solvent, drying, and then placing the mixture in a microwave reaction furnace to perform a low-temperature reduction reaction. The product is treated by water immersion, suction filtration and drying to obtain high-purity TiB2 powder. The reducing agent is a mixed reducing agent of Al powder and carbon powder, and an alkaline additive is introduced to activate the reaction and promote the reaction at low temperature. Meanwhile, by taking advantage of microwave heating, high-purity TiB2 powder with small crystal grains (D50<1.0 mm) and low carbon and oxygen content (<0.35%) is prepared at 700-1000 DEG C for 5-25 min. Compared with the existing TiB2 preparation method with high energy consumption (1500-2000 DEG C), low efficiency (15-30 h) and high cost, the method has the advantages of low reduction temperature and short time, high product purity, low energy consumption, high efficiency, green pollution-free and low cost, and the process is simple and easy to control, and can be applied to industrialized mass production of TiB2.

Description

Technical Field

[0001] This invention relates to the field of ceramic powder preparation, specifically to a method for preparing high-purity TiB2 powder at low temperature and with high efficiency. Background Technology

[0002] Titanium diboride (TiB2), as a high-temperature resistant ceramic material, possesses excellent properties such as high hardness, high melting point, good chemical stability, wear resistance, and good electrical and thermal conductivity. It has wide applications in cutting tools, metal (ceramic) matrix composites, wear-resistant parts, and cathode materials for aluminum electrolytic cells. The key to its application performance lies in the quality (purity and particle size) of TiB2 powder. Therefore, how to prepare high-quality TiB2 powder remains a focus and hot topic of current research.

[0003] The main methods for preparing TiB2 powder include boronothermal / carbothermal reduction, carbothermal reduction, self-propagating high-temperature method, mechanical alloying, and sol-gel method. Among these, mechanical alloying and sol-gel methods hold promise for preparing nanoscale TiB2 powder, but their processes are complex and their production costs are high, making industrial-scale production difficult. TiB2 prepared by self-propagating high-temperature methods (including aluminothermal, siliconothermal, and magnesiumothermal reduction methods) has a high impurity content, requiring acid washing for impurity removal, which is difficult to completely remove, resulting in low purity. Patent CN114873600A discloses a method for preparing high-purity TiB2 ceramic powder using a self-propagating high-temperature method. TiO2, a boron source (boron oxide / boric acid), and Ca / Mg powder are mixed uniformly and placed in a self-propagating reactor. Under argon protection, a self-propagating reaction is initiated (400℃~700℃) to obtain crude TiB2 product. The crude product is then acid-leached, washed, and dried to obtain TiB2 powder. However, this method involves many types of impurity phases, requiring multiple acid washing purification processes that are difficult to completely remove, resulting in a complex process and severe environmental pollution. Currently, the industrial method for large-scale production of TiB2 is the boronothermal / carbothermal reduction method, which involves uniformly mixing titanium dioxide, carbon black, and boron carbide, reducing them at a high temperature of 1500–2000℃ for 15–30 hours, and then crushing and classifying them by air jet milling to obtain micron-sized TiB2 powder. However, this method has high reduction temperature and high energy consumption, and the prepared TiB2 powder has a high content of residual carbon and O impurities (C>0.6%, O>1.2%), which seriously reduces its sintering performance. In addition, the reaction time of 15–30 hours is not only inefficient, but the continuous high temperature also causes abnormal coarsening of TiB2 grains, which is not conducive to its subsequent ceramic sintering. Carbothermal reduction is a common synthesis method for TiB2 powder. V. Moradi et al. prepared TiB2 with a residual carbon content of 0.92% and a D50 of 3.28 μm by reacting at 1380 °C for 1 h after mechanical activation by ball milling for 24 h using TiO2, H3BO3 and graphite as raw materials (V. Moradi, L. Nikzad, I. Mobasherpour. Low temperature synthesis of titaniumdiboride by carbothermal method[J], Ceramicas International, 44(2018):19421-19426). However, the purity of TiB2 was low and it required 24 h of mechanical activation, resulting in low efficiency.

[0004] In summary, current methods for preparing TiB2 ceramic powder all have shortcomings: such as high reaction temperature, long reaction time, poor product activity; complex preparation process, difficult process control; high impurity content and low purity of the product; and environmental pollution caused by acid / alkali washing purification process. How to prepare high-purity TiB2 at low temperature and with high efficiency remains an urgent technical problem to be solved. Summary of the Invention

[0005] This invention addresses the shortcomings of existing TiB2 powder preparation technologies by proposing a method for preparing TiB2 powder that is low in energy consumption, high in efficiency, high in purity, uses readily available raw materials, has a simple process, is environmentally friendly, and is easy to industrialize.

[0006] To achieve the above objectives, the specific technical solution of the present invention is as follows:

[0007] A method for preparing high-purity TiB2 powder at low temperature and with high efficiency includes the following steps:

[0008] Step 1: Mix the four raw materials, namely titanium source, boron source, reducing agent and alkaline additive, in a molar ratio of 2:(1-4):(3-12):(1-10); the reducing agent is a mixture of Al powder and carbon powder in a molar ratio of (0.5-1.2):1.

[0009] Step 2: Load the prepared raw materials into a ball mill jar for wet ball milling, and then dry them after the ball milling is completed.

[0010] Step 3: Place the dried raw material into a microwave oven for reaction at a temperature of 700-1000℃ for 2-25 minutes.

[0011] Step 4: The reaction product is soaked in water at 40-100℃, filtered, and then dried in an oven at 80-150℃ for 6-12 hours to obtain high-purity TiB2 powder.

[0012] Furthermore, the alkaline auxiliary agent is one or more of NaNO2, NaNO3, KNO2, KNO3, Na2O, and K2O.

[0013] Furthermore, the boron source is one or more of boron carbide, anhydrous sodium tetraborate, sodium metaborate, and potassium metaborate.

[0014] Furthermore, the titanium source is one or more of TiO2 powder, sodium titanate, and potassium titanate.

[0015] Furthermore, the carbon powder is one or more of graphite, carbon black, and activated carbon.

[0016] Furthermore, the reactor described in step 3 is either continuous or intermittent, with a microwave power of 4KW to 8KW and a heating rate of 30 to 110℃ / min.

[0017] Further, the wet ball milling in step 2 is performed using deionized water or an organic solvent and zirconia balls as the milling medium; wherein the mass ratio of the balls:raw material:deionized water or organic solvent is controlled at 5:1:(2~20), the ball mill speed is 400 r / min, the ball milling time is 1~12 h, the drying temperature is 80~150℃, and the drying time is 6~12 h.

[0018] Furthermore, the obtained TiB2 powder has an average particle size (D50) <1.0 μm, a purity >99.3%, and C and O contents both less than 0.35%.

[0019] On the other hand, the present invention can also dehydrate the obtained filtrate as a by-product to obtain high-purity NaAlO2 / KAlO2 by-product, effectively realizing the recycling and reuse of by-products.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] (1) Using Al powder and carbon powder as a mixed reducing agent, in addition to utilizing the high reactivity of Al powder as a reducing agent, the reducing atmosphere generated by the carbon powder reducing agent can effectively inhibit the oxidation of Al powder as a reducing agent, reduce the content of Al2O3 byproducts, and improve the purity of TiB2. Al powder melts into a liquid state at 660℃, and Al powder is easy to volatilize during the reaction process. The reducing atmosphere generated by the carbon powder reducing agent can effectively inhibit the volatilization of Al, greatly improving the utilization rate of Al powder. Furthermore, the reducing gas generated by the carbon powder reducing agent can accelerate the reaction rate, improve the reduction efficiency, and greatly reduce the amount of Al powder reducing agent used (about 40%). The use of mixed reducing agents can effectively reduce the reaction temperature (<1000℃), realize the combination of self-propagating high-temperature method (aluminothermic) and carbothermic method, shorten the reaction time, and improve the reduction efficiency. At the same time, carbon powder reducing agent is inexpensive, which can significantly reduce production costs.

[0022] (2) Currently, the industrial preparation temperature of TiB2 powder is above 1500℃ and the time is >1h. The high reaction temperature and long reaction time result in coarse TiB2 powder grains and uneven particle size distribution. This invention uses microwave heating, which takes advantage of the high energy utilization rate of microwaves, the absence of temperature gradient, and the fast heating speed. At the same time, the non-thermal effect of microwaves reduces the apparent activation energy of the reaction, which can accelerate the reaction rate. The reaction temperature is reduced to 700-1000℃, and after holding at this temperature for 2-25 minutes, high-purity TiB2 powder is obtained with an average particle size (D50) of less than 1.0μm.

[0023] (3) Adding one or more of NaNO2, NaNO3, KNO2, KNO3, Na2O and K2O to the raw materials can effectively remove the main byproduct Al2O3 in the reaction products, improve the purity of TiB2, and promote the forward reaction, thereby increasing the yield of TiB2 and the reaction efficiency.

[0024] (4) The filtrate obtained in this invention is used as a by-product for dehydration treatment. The high-purity NaAlO2 / KAlO2 by-product can be used in many fields, effectively realizing the recycling and reuse of by-products, reducing production costs, reducing environmental pollution, and is a green and environmentally friendly production process with important social, economic and environmental value. Attached Figure Description

[0025] Figure 1 This is the XRD pattern of TiB2 powder obtained in Example 3 of the present invention.

[0026] Figure 2 The image shows the XRD pattern of TiB2 powder obtained in Comparative Example 1 of this invention.

[0027] Figure 3 The image shows the XRD pattern of the TiB2 powder obtained in Comparative Example 3 of this invention.

[0028] Figure 4 This is a SEM image of the TiB2 powder obtained in Example 3 of the present invention.

[0029] Figure 5 This is a SEM image of the TiB2 powder obtained in Comparative Example 3 of the present invention.

[0030] Figure 6 This is a particle size distribution diagram of the TiB2 powder obtained in Example 3 of the present invention. Detailed Implementation

[0031] The present invention will now be described in detail with reference to the accompanying drawings.

[0032] A method for preparing high-purity TiB2 powder at low temperature and with high efficiency includes the following steps:

[0033] Step 1: Mix the four raw materials—titanium source, boron source, reducing agent, and alkaline additive—in a molar ratio of 2:(1-4):(3-12):(1-10). The reducing agent is a mixture of Al powder and carbon powder in a molar ratio of (0.5-1.2):1. The alkaline additive is one or more of NaNO2, NaNO3, KNO2, KNO3, Na2O, and K2O. The boron source is one or more of boron carbide, anhydrous sodium tetraborate, sodium metaborate, and potassium metaborate. The titanium source is one or more of TiO2 powder, sodium titanate, and potassium titanate. The carbon powder is one or more of graphite, carbon black, and activated carbon.

[0034] Step 2: Load the prepared raw materials into a ball mill jar for wet ball milling. The wet ball milling is carried out with deionized water or organic solvent and zirconia balls as the ball milling medium. The mass ratio of balls:raw materials:deionized water or organic solvent is controlled at 5:1:(2~20). The ball mill speed is 400 r / min and the ball milling time is 1~12 h. After the ball milling is completed, the materials are dried at a temperature of 80~150℃ for 6~12 h.

[0035] Step 3: Place the dried raw material into a microwave reactor for reaction. The reactor can be continuous or intermittent, with a microwave power of 4KW to 8KW, a heating rate of 30 to 110℃ / min, a reaction temperature of 700 to 1000℃, and a reaction time of 2 to 25 min.

[0036] Step 4: The reaction product is soaked in water at 40-100℃, filtered, and then dried in an oven at 80-150℃ for 6-12 hours to obtain high-purity TiB2 powder. The average particle size (D50) of the obtained TiB2 powder is <1.0μm, the purity is >99.3%, and the C and O contents are both less than 0.35%.

[0037] Step 5 involves dehydrating the obtained filtrate as a byproduct to obtain high-purity NaAlO2 / KAlO2 byproducts, effectively realizing the recycling and reuse of byproducts.

[0038] To better illustrate the present invention and facilitate understanding of its technical solutions, the present invention will be further described in detail below. However, the following embodiments are merely simplified examples of the present invention and do not represent or limit the scope of protection of the present invention. The scope of protection of the present invention is determined by the claims.

[0039] The following are typical but non-limiting embodiments of the present invention:

[0040] Example 1

[0041] A method for preparing high-purity TiB2 powder at low temperature and with high efficiency includes the following steps:

[0042] Step 1: Mix the five raw materials TiO2, boron carbide, Al powder, carbon powder and KNO2 in a molar ratio of 2:1:1.85:3.7:4.7.

[0043] Step 2: Load the prepared raw materials into a ball mill jar and add deionized water or organic solvent. Use zirconia balls as the milling medium, and control the mass ratio of balls:material:deionized water or organic solvent at 5:1:(2-20). Mill at 400 r / min for 1-12 hours until uniformly mixed. After milling, place in an oven at 80-150℃ for 6-12 hours for drying.

[0044] Step 3: Place the dried raw material into a microwave reactor for reaction. The heating rate is 40℃ / min, the reaction temperature is 1000℃, and the reaction time is 5min.

[0045] Step 4: The reaction product is soaked in water at 40-100℃, filtered, and then dried in an oven at 80-150℃ for 6-12 hours to obtain high-purity TiB2 powder.

[0046] Step 5: The obtained filtrate is dehydrated as a by-product to obtain high-purity KAlO2 by-product, effectively realizing the recycling and reuse of by-products.

[0047] The TiB2 powder prepared in this example has a purity of 99.35% and an average particle size of 0.5 μm.

[0048] Example 2

[0049] A method for preparing high-purity TiB2 powder at low temperature and with high efficiency includes the following steps:

[0050] Step 1: Potassium titanate, potassium metaborate, Al powder, carbon powder and KNO3 are mixed in a molar ratio of 2:3.3:1.48:1.78:4.7.

[0051] Step 2: Pour the prepared raw materials into a ball mill jar and add deionized water or organic solvent. Use zirconia balls as the milling medium, and control the mass ratio of balls:material:deionized water or organic solvent at 5:1:(2-20). Mill at 400 r / min for 1-12 hours until uniformly mixed. After milling, place in an oven at 80-150℃ for 6-12 hours for drying.

[0052] Step 3: Place the dried raw material into a microwave reactor for reaction. The heating rate is 50℃ / min, the reaction temperature is 700℃, and the reaction time is 10min.

[0053] Step 4: The reaction product is soaked in water at 40-100℃, filtered, and then dried in an oven at 80-150℃ for 6-12 hours to obtain high-purity TiB2 powder.

[0054] Step 5: The obtained filtrate is dehydrated as a by-product to obtain high-purity KAlO2 by-product, effectively realizing the recycling and reuse of by-products.

[0055] The TiB2 powder prepared in this example has a purity of 99.53% and an average particle size of 0.67 μm, which is high in purity and small in particle size.

[0056] Table 1 compares the chemical composition of the TiB2 powder obtained in Example 2 of this invention with that of commercially available TiB2 powder. As shown in the table, the commercially available TiB2 powder has a purity of 97.81%, an O content of 1.41%, and a carbon content of 0.78%, indicating low purity and high impurity content, especially high O impurity content, which is detrimental to subsequent sintering. In contrast, the TiB2 powder obtained in Example 2 of this invention has a purity as high as 99.53%, an O content of only 0.31%, and a carbon content of only 0.16%, demonstrating high purity and low impurity content, which meets the purity and impurity content requirements for subsequent sintering.

[0057] Table 1 Chemical composition of TiB2 ceramic powder obtained in Example 2 of the present invention

[0058]

[0059] Example 3

[0060] A method for preparing high-purity TiB2 powder at low temperature and with high efficiency includes the following steps:

[0061] Step 1: The five raw materials, TiO2, anhydrous sodium tetraborate, Al powder, carbon powder and NaNO2, are mixed in a molar ratio of 2:1:4:4:2.

[0062] Step 2: Pour the prepared raw materials into a ball mill jar and add deionized water or organic solvent. Use zirconia balls as the milling medium, and control the mass ratio of balls:material:deionized water or organic solvent at 5:1:(2-20). Mill at 400 r / min for 1-12 hours until uniformly mixed. After milling, place in an oven at 80-150℃ for 6-12 hours for drying.

[0063] Step 3: Place the dried raw material into a microwave reactor for reaction. The heating rate is 100℃ / min, the reaction temperature is 1000℃, and the reaction time is 25min.

[0064] Step 4: The reaction product is soaked in water at 80-100℃, filtered, and then dried in an oven at 80-150℃ for 6-12 hours to obtain high-purity TiB2 powder.

[0065] Step 5 involves dehydrating the obtained filtrate as a byproduct to obtain high-purity NaAlO2 byproduct, effectively realizing the recycling and reuse of byproducts.

[0066] The TiB2 powder prepared in this example has a purity of 99.68% and an average particle size of 0.96 μm.

[0067] Using Al powder and C powder as a mixed reducing agent, the reaction equation in this example is as follows: 2TiO2 + Na2B4O7 + 4Al + 2NaNO2 + 4C = 2TiB2 + 4NaAlO2 + 4CO + NO + NO2. It can be seen that TiO2:Al = 1:2, that is, to generate 1 mol TiB2, 2 mol Al reducing agent + 2 mol C reducing agent are required.

[0068] Figure 1 This is the XRD pattern of the TiB2 powder obtained in this embodiment. Figure 1 It can be seen that the obtained TiB2 powder did not contain any other impurity phases, and the phase purity of TiB2 was above 99%. Figure 4 This is a SEM image of the TiB2 powder obtained in this embodiment. As can be seen from the image, the individual grain size is between 30 and 500 nm, with a regular shape and a typical hexagonal structure. Figure 6 This is a particle size distribution diagram of the TiB2 powder obtained in this embodiment. Figure 6 It can be clearly seen that the average particle size is 0.96 μm and the particle size distribution is uniform.

[0069] Example 4

[0070] A method for preparing TiB2 powder includes the following steps:

[0071] Step 1: Sodium titanate, boron carbide, anhydrous sodium tetraborate, Al powder, carbon powder and NaNO2 are mixed in a molar ratio of 2:1:1:2:1.

[0072] Step 2: Pour the prepared raw materials into a ball mill jar and add deionized water or organic solvent. Use zirconia balls as the milling medium, and control the mass ratio of balls:material:deionized water or organic solvent at 5:1:(2-20). Mill at 400 r / min for 1-12 hours until uniformly mixed. After milling, place in an oven at 80-150℃ for 6-12 hours for drying.

[0073] Step 3: Place the dried raw material into a microwave reactor for reaction. The heating rate is 100℃ / min, the reaction temperature is 900℃, and the reaction time is 25min.

[0074] Step 4: The reaction product is soaked in water at 80-100℃, filtered, and then dried in an oven at 80-150℃ for 6-12 hours to obtain TiB2 powder.

[0075] Step 5: The obtained filtrate is dehydrated as a by-product to obtain high-purity NaAlO2 by-product, effectively realizing the recycling and reuse of by-products.

[0076] The TiB2 powder prepared in this example has a purity of 99.42% and an average particle size of 1.8 μm.

[0077] Example 5

[0078] A method for preparing TiB2 powder includes the following steps:

[0079] Step 1: The four raw materials, TiO2, sodium metaborate, Al powder, carbon powder and NaNO2, are mixed in a molar ratio of 2:1:1.64:1.36:1.

[0080] Step 2: Pour the prepared raw materials into a ball mill jar and add deionized water or organic solvent. Use zirconia balls as the milling medium, and control the mass ratio of balls:material:deionized water or organic solvent at 5:1:(2-20). Mill at 400 r / min for 1-12 hours until uniformly mixed. After milling, place in an oven at 80-150℃ for 6-12 hours for drying.

[0081] Step 3: Place the dried raw material into a microwave reactor for reaction. The heating rate is 75℃ / min, the reaction temperature is 1000℃, and the reaction time is 15min.

[0082] Step 4: The reaction product is soaked in water at 80-100℃, filtered, and then dried in an oven at 80-150℃ for 6-12 hours to obtain TiB2 powder.

[0083] Step 5: The obtained filtrate is dehydrated as a by-product to obtain high-purity NaAlO2 by-product, effectively realizing the recycling and reuse of by-products.

[0084] The TiB2 powder prepared in this example has a purity of 99.31% and an average particle size of 0.8 μm.

[0085] Example 6

[0086] A method for preparing TiB2 powder includes the following steps:

[0087] Step 1: Sodium titanate, anhydrous sodium tetraborate, Al powder, carbon powder and NaNO3 are mixed in a molar ratio of 1:2:2:4:5.

[0088] Step 2: Pour the prepared raw materials into a ball mill jar and add deionized water or organic solvent. Use zirconia balls as the milling medium, and control the mass ratio of balls:material:deionized water or organic solvent at 5:1:(2-20). Mill at 400 r / min for 1-12 hours until uniformly mixed. After milling, place in an oven at 80-150℃ for 6-12 hours for drying.

[0089] Step 3: Place the dried raw material into a microwave reactor for reaction. The heating rate is 100℃ / min, the reaction temperature is 1200℃, and the reaction time is 25min.

[0090] Step 4: The reaction product is soaked in water at 80-100℃, filtered, and then dried in an oven at 80-150℃ for 6-12 hours to obtain TiB2 powder.

[0091] Step 5: The obtained filtrate is dehydrated as a by-product to obtain high-purity NaAlO2 by-product, effectively realizing the recycling and reuse of by-products.

[0092] The TiB2 powder prepared in this example has a purity of 99.6% and an average particle size of 2.4 μm.

[0093] Example 7

[0094] A method for preparing TiB2 powder includes the following steps:

[0095] Step 1: Sodium titanate, boron carbide, Al powder, carbon powder and NaNO3 are mixed in a molar ratio of 1:2:3.28:2.72:5.

[0096] Step 2: Pour the prepared raw materials into a ball mill jar and add deionized water or organic solvent. Use zirconia balls as the milling medium, and control the mass ratio of balls:material:deionized water or organic solvent at 5:1:(2-20). Mill at 400 r / min for 1-12 hours until uniformly mixed. After milling, place in an oven at 80-150℃ for 6-12 hours for drying.

[0097] Step 3: Place the dried raw material into a microwave reactor for reaction. The heating rate is 100℃ / min, the reaction temperature is 1100℃, and the reaction time is 25min.

[0098] Step 4: The reaction product is soaked in water at 80-100℃, filtered, and then dried in an oven at 80-150℃ for 6-12 hours to obtain TiB2 powder.

[0099] Step 5: The obtained filtrate is dehydrated as a by-product to obtain high-purity NaAlO2 by-product, effectively realizing the recycling and reuse of by-products.

[0100] The TiB2 powder prepared in this example has a purity of 99.56% and an average particle size of 1.3 μm.

[0101] Comparative Example 1

[0102] A method for preparing TiB2 powder includes the following steps:

[0103] Step 1: The four raw materials, TiO2, anhydrous sodium tetraborate, Al powder and NaNO2, are mixed in a molar ratio of 2:1:6.67:4.67.

[0104] Step 2: Pour the prepared raw materials into a ball mill jar and add deionized water or organic solvent. Use zirconia balls as the milling medium, and control the mass ratio of balls:material:deionized water or organic solvent at 5:1:(2-20). Mill at 400 r / min for 1-12 hours until uniformly mixed. After milling, place in an oven at 80-150℃ for 6-12 hours for drying.

[0105] Step 3: Place the dried raw material into a microwave reactor for reaction. The heating rate is 100℃ / min, the reaction temperature is 1000℃, and the reaction time is 25min.

[0106] Step 4: The reaction product is soaked in water at 80-100℃, filtered, and then dried in an oven at 80-150℃ for 6-12 hours to obtain TiB2 powder.

[0107] The TiB2 powder prepared in this example has a purity of 85.3% and an average particle size of 2.4 μm.

[0108] Using pure Al as the reducing agent, the reaction in this example is based on the following reaction equation: 6TiO2 + 3Na2B4O7 + 20Al + 14NaNO2 = 6TiB2 + 20NaAlO2 + 7NO + 7NO2. It can be seen that the molar ratio of TiO2 to Al in the raw materials is 3:10, that is, 3.33 mol of Al reducing agent is required to produce 1 mol of TiB2.

[0109] Figure 2 The images show the XRD patterns of TiB2 powder obtained before and after water immersion in this embodiment (1000℃ Z represents water immersion). From... Figure 2 It can be seen that the Na-containing impurity phase in the obtained TiB2 powder is Na2Al2B2O7, not NaAlO2, and the phase purity of TiB2 is only about 35%.

[0110] Comparative Example 2

[0111] A method for preparing TiB2 powder includes the following steps:

[0112] Step 1: The five raw materials, sodium titanate, sodium metaborate, Al powder, carbon powder and NaNO3, are mixed in a molar ratio of 2:3.3:1.48:3.7:4.7.

[0113] Step 2: Pour the prepared raw materials into a ball mill jar and add deionized water or organic solvent. Use zirconia balls as the milling medium, and control the mass ratio of balls:material:deionized water or organic solvent at 5:1:(2-20). Mill at 400 r / min for 1-12 hours until uniformly mixed. After milling, place in an oven at 80-150℃ for 6-12 hours for drying.

[0114] Step 3: Place the dried raw material into a microwave reactor for reaction. The heating rate is 70℃ / min, the reaction temperature is 1100℃, and the reaction time is 15min.

[0115] Step 4: The reaction product is soaked in water at 40-100℃, filtered, and then dried in an oven at 80-150℃ for 6-12 hours to obtain TiB2 powder.

[0116] The TiB2 powder prepared in this example has a purity of only 45%, residual C is present in XRD, and the average particle size is 0.75 μm.

[0117] Comparative Example 3

[0118] A method for preparing TiB2 powder includes the following steps:

[0119] Step 1: The four raw materials, TiO2, anhydrous sodium tetraborate, Al powder, carbon powder and NaNO2, are mixed in a molar ratio of 2:1:7.2:4:2.

[0120] Step 2: Pour the prepared raw materials into a ball mill jar and add deionized water or organic solvent. Use zirconia balls as the milling medium, and control the mass ratio of balls:material:deionized water or organic solvent at 5:1:(2-20). Mill at 400 r / min for 1-12 hours until uniformly mixed. After milling, place in an oven at 80-150℃ for 6-12 hours for drying.

[0121] Step 3: Place the dried raw material into a microwave reactor for reaction. The heating rate is 100℃ / min, the reaction temperature is 1200℃, and the reaction time is 25min.

[0122] Step 4: The reaction product is soaked in water at 80-100℃, filtered, and then dried in an oven at 80-150℃ for 6-12 hours to obtain TiB2 powder.

[0123] The XRD pattern of the TiB2 powder obtained in this comparative example. Figure 3It can be seen that the obtained TiB2 powder has obvious Al2O3 diffraction peaks, and the phase purity of TiB2 is about 75%. Figure 5 The image shows the SEM image of the TiB2 powder obtained in this comparative example. As can be seen from the image, the size of a single TiB2 grain is greater than 500 nm, and a large number of Al2O3 grains are attached to the surface of the TiB2 grains, making it difficult to separate TiB2 and Al2O3.

[0124] The analysis results of the TiB2 powder obtained by comparing Example 3 and Comparative Example 1 show that the use of a mixed reducing agent of Al powder and carbon powder can significantly reduce the content of by-products such as Al2O3, improve the purity of TiB2 powder, and greatly reduce the amount of Al powder reducing agent used (the molar ratio of reducing agent is reduced by about 40% compared to pure Al powder).

[0125] The embodiments described above are preferred embodiments of the present invention and do not impose any other limitations on the present invention. Any person skilled in the art may make changes or imitations based on the above content. However, any changes made to the above embodiments based on the essence of the method of the present invention without departing from the scope of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A method for preparing high-purity TiB2 powder at low temperature and with high efficiency, characterized in that, Includes the following steps: Step 1: Mix the four raw materials—titanium source, boron source, reducing agent, and additives—in a molar ratio of 2:(1-4):(3-12):(1-10); the reducing agent is a mixture of Al powder and carbon powder in a molar ratio of (0.5-1.2):1; the additives are one or more of NaNO2, NaNO3, KNO2, KNO3, Na2O, and K2O. Step 2: Load the prepared raw materials into a ball mill jar for wet ball milling, and then dry them after the ball milling is completed. Step 3: Place the dried raw material into a microwave oven for reaction at a temperature of 700-1000℃ for 2-25 minutes. Step 4: The reaction product is soaked in water at 40~100℃, filtered, and then dried in an oven at 80~150℃ for 6~12 hours to obtain high-purity TiB2 powder with a purity >99.3%.

2. The method for preparing high-purity TiB2 powder at low temperature and high efficiency according to claim 1, characterized in that, The boron source is one or more of boron carbide, anhydrous sodium tetraborate, sodium metaborate, and potassium metaborate.

3. The method for preparing high-purity TiB2 powder at low temperature and high efficiency according to claim 1, characterized in that, The titanium source is one or more of TiO2 powder, sodium titanate, and potassium titanate.

4. The method for preparing high-purity TiB2 powder at low temperature and high efficiency according to claim 1, characterized in that, The carbon powder is one or more of graphite, carbon black, and activated carbon.

5. The method for preparing high-purity TiB2 powder at low temperature and high efficiency according to claim 1, characterized in that, The reactor described in step 3 is either continuous or intermittent, with a microwave power of 4KW~8KW and a heating rate of 30~110℃ / min.

6. The method for preparing high-purity TiB2 powder at low temperature and high efficiency according to claim 1, characterized in that, Step 2 describes wet ball milling, which involves using deionized water or an organic solvent and zirconia balls as the milling medium. The mass ratio of balls to raw materials to deionized water or organic solvent is controlled at 5:1:(2~20). The ball mill speed is 400 r / min, the milling time is 1~12 h, the drying temperature is 80~150℃, and the drying time is 6~12 h.

Images