A method for producing a nanoscale tungsten-based composite powder doped with carbide particles

Abstract

The application discloses a preparation method of a nano tungsten-based composite powder doped with carbide particles, and comprises the following steps: 1, ball-milling and uniformly dispersing tungsten trioxide to obtain pretreated tungsten source powder; 2, dispersing and surface modifying nano carbide particles, and low-energy ball-milling the nano carbide particles with the pretreated tungsten source powder to obtain nano zirconium carbide-tungsten trioxide composite powder; 3, mixing the nano zirconium carbide-tungsten trioxide composite powder with carbon nano particles, and carrying out carbon thermal pre-reduction to obtain pre-reduction powder; and 4, hydrogen-reducing the pre-reduction powder to obtain the nano tungsten-based composite powder doped with uniform carbide particles. By introducing the nano carbide particles and the carbon nano particles, and by cooperating with the carbon thermal pre-reduction and the hydrogen reduction, the nucleation rate in the reduction process is remarkably improved, the tungsten powder granularity is effectively refined, the dispersivity of the nano carbide particles and the tungsten powder particle size are regulated, and finally the nano tungsten-based composite powder doped with uniform carbide particles is obtained.

Description

Technical Field

[0001] This invention belongs to the field of powder preparation engineering technology, specifically relating to a method for preparing nano-tungsten-based composite powder doped with carbide particles. Background Technology

[0002] Tungsten metal possesses a range of excellent physical and chemical properties, including an extremely high melting point (approximately 3410℃), good high-temperature strength, high elastic modulus, excellent electrical and thermal conductivity, strong corrosion resistance, low coefficient of thermal expansion, low vapor pressure and evaporation rate, as well as a high sputtering threshold and low hydrogen / helium retention rate. Based on these characteristics, tungsten and its alloys have irreplaceable application value in key industrial fields such as nuclear energy, aerospace, defense, electronics, chemical engineering, and metallurgy.

[0003] Carbide ceramics possess extremely high hardness and wear resistance. Introducing them into a tungsten matrix can significantly improve the material's room-temperature and high-temperature mechanical properties and thermal stability. However, the traditional process of mixing tungsten powder and carbides and then sintering often suffers from problems such as large raw material particle size, low sintering activity, uneven mixing, and coarse mixing scale. This leads to higher sintering temperatures, coarser microstructure, abnormal growth of the second phase, and its concentration at grain boundaries, making it difficult to obtain the ideal microstructure and overall performance. Although researchers have tried various improvement methods, such as high-energy ball milling alloying and solid-liquid mixing processes, they still generally face challenges such as severe particle agglomeration, poor dispersibility, difficulty in accurately controlling the particle size and distribution uniformity of the tungsten matrix and the second phase, high cost, and difficulty in scaling up the process.

[0004] Therefore, the preparation of tungsten-based nanoparticle composite powders doped with carbide particles still faces many challenges. How to achieve efficient doping of nanoparticles with carbide particles and control the particle size of tungsten powder at low cost and high efficiency is a current challenge in the field. Summary of the Invention

[0005] The technical problem to be solved by this invention is to address the shortcomings of the prior art by providing a method for preparing tungsten nanoparticle-doped composite powder. This method introduces tungsten nanoparticles and carbon nanoparticles, and through the combination of carbothermal pre-reduction and hydrogen reduction, significantly improves the nucleation rate during the reduction process, effectively refines the particle size of the tungsten powder, and achieves control over the dispersibility of the tungsten nanoparticles and the size of the tungsten powder particles, ultimately obtaining a uniformly doped tungsten nanoparticle-doped composite powder.

[0006] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is: a method for preparing tungsten-based nanoparticle composite powder doped with carbide particles, characterized in that the method includes the following steps: Step 1: Place tungsten trioxide in a solvent and add a dispersant, then ball mill and disperse it evenly. After drying, obtain pretreated tungsten source powder. Step 2: The nano carbide particles are dispersed and surface modified with the aid of a dispersant, and then mixed with the pretreated tungsten source powder obtained in Step 1. After low-energy ball milling and drying, uniformly dispersed nano zirconium carbide-tungsten trioxide composite powder is obtained. Step 3: Mix the nano-zirconium carbide-tungsten trioxide composite powder obtained in Step 2 with carbon nanoparticles evenly, and then perform carbothermic pre-reduction by heating and heat preservation to obtain pre-reduced powder. Step 4: After spreading the pre-reduced powder obtained in Step 3, hydrogen reduction is carried out to finally obtain nano-tungsten-based composite powder with uniformly doped carbide particles.

[0007] This invention uses ball-milled and uniformly dispersed tungsten trioxide as the tungsten source, with nanoscale refractory carbide particles as the reinforcing phase. Through the synergistic effect of dispersion and surface modification, the surface structure of the carbide is improved, enhancing wettability and dispersibility. Then, low-energy ball milling achieves uniform mixing of tungsten trioxide and nanoscale carbide particles at the nanoscale, regulating the dispersibility and pore structure of the mixed powder, providing channels for gas phase migration and nucleation, and inhibiting the agglomeration of tungsten particles during subsequent reduction. Afterwards, the powder is uniformly mixed with carbon nanoparticles and pre-reduced carbothermally. In the pre-reduced powder, since the carbothermal effect is insufficient to completely reduce tungsten trioxide to tungsten, a small amount of oxide is retained to control the carbon content, facilitating subsequent hydrogen reduction. Furthermore, the carbon nanoparticles in the carbothermal pre-reduction process act as a reducing agent during carbothermal reduction, and also serve as high-density nucleation sites driving uniform nucleation. They are largely consumed during carbothermal reduction, accompanied by significant volume shrinkage, generating a rich internal pore structure and in-situ submicron pores, effectively... The process effectively inhibits the coagulation and coarsening process between particles, suppresses grain boundary migration-driven particle coarsening, and helps to obtain ultrafine tungsten particles. Finally, combined with hydrogen reduction, the small amount of residual oxides in the pre-reduced powder are completely reduced. By using carbothermal pre-reduction and two-step reduction, the problem of generating gaseous intermediate product WO2(OH)2 and depositing on the surface of tungsten powder due to the chemical vapor migration mechanism in traditional hydrogen reduction is avoided, thus effectively inhibiting the growth of tungsten particles during the reduction process. The gaseous migration mechanism further promotes the uniform distribution of the reinforcing phase in the tungsten matrix. The dispersed nano-carbide particles serve as heterogeneous nucleation sites, promoting the formation of a large number of tungsten crystal nuclei on the surface of tungsten trioxide particles. Finally, a nano-tungsten-based composite powder with highly dispersed and uniformly doped carbide particles is obtained. This composite powder has high sintering activity and can be formed at a lower temperature to form a high-performance carbide dispersion-reinforced tungsten-based composite material, which significantly improves the mechanical properties of the composite material and overcomes the performance deficiencies caused by the easy agglomeration and uneven distribution of the reinforcing phase in traditional processes.

[0008] The method for preparing a nano-tungsten-based composite powder doped with carbide particles described above is characterized in that the average grain size of the tungsten trioxide in step one is less than 100 nm. This invention, by employing nanoscale tungsten trioxide, facilitates uniform mixing of tungsten trioxide and carbides at the nanoscale, suppressing the agglomeration of tungsten particles during subsequent reduction.

[0009] The method for preparing tungsten-based nanoparticle composite powder doped with carbide particles described above is characterized in that, in step one, the solvent is ethanol, the dispersant is polyethylene glycol, the mass of the solvent is 50%~70% of the mass of tungsten trioxide, the mass of the dispersant is 0.3%~0.6% of the mass of tungsten trioxide, the ball milling speed is 200r / min~300r / min, and the time is 2h~6h. This invention, by controlling the composition and mass of the solvent and dispersant, as well as the ball milling parameters, achieves optimal crushing and dispersion effects, facilitating the crushing and uniform dispersion of tungsten trioxide and promoting thorough and uniform mixing with nanoparticle carbide particles.

[0010] The method for preparing a nano-tungsten-based composite powder doped with carbide particles described above is characterized in that the nano-carbide particles in step two are nano-zirconium carbide particles with an average particle size of no more than 50 nm. This invention, by employing nano-zirconium carbide particles, possesses extremely high hardness and wear resistance. Introducing them into a tungsten metal matrix can significantly improve its room temperature and high temperature mechanical properties and thermal stability.

[0011] The method for preparing a nano-tungsten-based composite powder doped with carbide particles, as described above, is characterized in that the dispersant in step two is polyethylene glycol and / or polyvinylpyrrolidone, the mass ratio of the nano-carbide particles to the dispersant is 0.4~0.5:0.05~0.2, and the dispersion and surface modification are performed by ultrasonic treatment. This invention, by controlling the composition and proportion of the dispersant and employing ultrasonic treatment, enables the nano-carbide particles to be more diffusely distributed within the tungsten trioxide matrix, achieving uniform mixing with tungsten trioxide at the nanoscale, which helps to suppress the agglomeration of tungsten particles during subsequent reduction.

[0012] The method for preparing a nano-tungsten-based composite powder doped with carbide particles described above is characterized in that the mass ratio of the nano-carbide particles to the pretreated tungsten source powder in step two is 0.4~0.5:50~65. This invention, by controlling the mass ratio of nano-carbide particles to the pretreated tungsten source powder and incorporating an appropriate amount of nano-carbide particles, enables the composite powder to possess optimal room-temperature and high-temperature mechanical properties and thermal stability.

[0013] The method for preparing a nano-tungsten-based composite powder doped with carbide particles described above is characterized in that the carbon nanoparticles in step three are nano-carbon black with an average particle size not exceeding 50 nm and a carbon mass content greater than 98%. This invention utilizes nano-carbon black, which has the characteristics of large volume and fine particle size, and can serve as a dispersed nucleation site throughout the reaction process.

[0014] The method for preparing tungsten-based nanoparticle composite powder doped with carbide particles described above is characterized in that the mass of the carbon nanoparticles in step three is 5% to 10% of the mass of the zirconium carbide-tungsten trioxide composite powder. This invention promotes the formation of numerous tungsten crystal nuclei on the surface of tungsten trioxide particles by using an appropriate amount of carbon nanoparticles as heterogeneous nucleation sites. This prevents excessive doping from causing particle agglomeration, which would instead become a bonding center for tungsten particle agglomeration, ultimately leading to particle coarsening and reduced powder size uniformity.

[0015] The method for preparing tungsten-based nanoparticle composite powder doped with carbide particles described above is characterized in that the carbothermic pre-reduction temperature in step three is 950℃~1050℃, and the holding time is 2h~4h. This invention, through the parameters of the carbothermic pre-reduction, ensures that a large amount of tungsten trioxide is reduced to tungsten, while retaining a small amount of oxide to control the carbon content. This allows carbon nanoparticles to act as high-density nucleation sites, driving uniform nucleation and effectively suppressing grain boundary migration-driven particle coarsening, thus contributing to the acquisition of ultrafine tungsten particles.

[0016] The method for preparing nano-tungsten-based composite powder doped with carbide particles described above is characterized in that the hydrogen reduction temperature in step four is 750℃~850℃, and the holding time is 1h~4h. This invention, by controlling the parameters of hydrogen reduction, ensures that tungsten trioxide is reduced while the particle size of the composite powder does not easily increase, preventing insufficient powder coarsening caused by excessively high reduction temperatures or excessively long holding times.

[0017] Compared with the prior art, the present invention has the following advantages: 1. This invention optimizes the surface properties of nano-carbide particles through the synergistic effect of surface modification and dispersant, thereby improving their wettability and dispersion stability in the system. This lays the foundation for achieving uniform mixing of nano-carbide and tungsten trioxide-containing nanocomposite powder, and controls the distribution of nano-carbide in tungsten-based composite materials from the source.

[0018] 2. The present invention uses tungsten trioxide as the tungsten source, which not only improves the mixing uniformity with nano carbide particles, but also enhances the stability of tungsten particles in subsequent processing. At the same time, it promotes the uniform distribution of nano carbides in the alloy and realizes the control of particle size and dispersion state.

[0019] 3. This invention further promotes the uniform distribution of the reinforcing phase in the tungsten matrix through the gas phase transport mechanism in the process of carbothermic pre-reduction combined with hydrogen reduction, which is beneficial for the subsequent preparation of high-performance tungsten-based composite materials with dispersed carbide distribution.

[0020] 4. The method for preparing tungsten-based nanoparticle composite powder doped with carbide particles of the present invention aims to achieve highly uniform dispersion of tungsten matrix and nanoparticle carbide. The average grain size of the composite powder obtained by this method can be refined to below 100 nm, and the grain size distribution is concentrated. At the same time, compared with traditional coarse-grained carbides with large grain boundary distribution, the carbides in the present invention can be uniformly doped in the tungsten matrix, which provides a good precursor basis for subsequent sintering to prepare tungsten-based composite materials with uniform carbide particle distribution and excellent mechanical properties.

[0021] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0022] Figure 1 This is a SEM image of the tungsten and zirconium carbide nanocomposite powder prepared in Example 1 of the present invention.

[0023] Figure 2 This is a TEM image of the tungsten and zirconium carbide nanocomposite powder prepared in Example 1 of the present invention. Detailed Implementation

[0024] Example 1 This embodiment includes the following steps: Step 1: Place tungsten trioxide with an average grain size of less than 80 nm in 60% ethanol and add 0.5% polyethylene glycol by weight of tungsten trioxide. Then ball mill at 300 r / min for 6 h and dry to obtain pretreated tungsten source powder. Step 2: Mix 0.5g of zirconium carbide nanoparticles with an average particle size of 40nm with 0.2g of polyvinylpyrrolidone. Under continuous stirring and ultrasonic treatment, a uniformly dispersed zirconium carbide nanoparticle suspension is obtained. Then, 50g of the pretreated tungsten source powder obtained in Step 1 is added to the zirconium carbide nanoparticle suspension. After that, the mixture is ball-milled at a speed of 200r / min and dried to obtain a uniformly dispersed zirconium carbide-tungsten trioxide composite powder. Step 3: Add 5% by mass of nano-carbon black with an average particle size of 20 nm and a carbon content greater than 98% to the nano-zirconium carbide-tungsten trioxide composite powder obtained in Step 2, mix evenly, and then keep at 950℃ for 4 h for carbothermal pre-reduction to obtain pre-reduced powder. Step 4: After spreading the pre-reduced powder obtained in Step 3, reduce it with hydrogen at 900℃ for 1 hour to finally obtain nano-tungsten-based composite powder with uniformly doped carbide particles.

[0025] Figure 1 This is a SEM image of the tungsten and zirconium carbide nanocomposite powder prepared in this embodiment. Figure 2 This is a TEM image of the tungsten and zirconium carbide nanocomposite powder prepared in Example 1 of this invention. Figure 1 and Figure 2 As can be seen from the figure, the average particle size of the uniformly doped carbide nano-tungsten-based composite powder prepared in this embodiment is about 80 nm; wherein the average particle size of the dispersed carbide particles is about 25 nm.

[0026] Example 2 This embodiment includes the following steps: Step 1: Place tungsten trioxide with an average grain size of less than 100 nm in 60% ethanol by mass of tungsten trioxide and add 0.3% polyethylene glycol by mass of tungsten trioxide. Then ball mill at 200 r / min for 4 h and dry to obtain pretreated tungsten source powder. Step 2: Mix 0.4g of zirconium carbide nanoparticles with an average particle size of 50nm with 0.05g of polyethylene glycol. Under continuous stirring and ultrasonic treatment, a uniformly dispersed zirconium carbide nanoparticle suspension is obtained. Then, 60g of the pretreated tungsten source powder obtained in Step 1 is added to the zirconium carbide nanoparticle suspension. After that, the mixture is ball-milled at a speed of 300r / min and dried to obtain a uniformly dispersed zirconium carbide-tungsten trioxide composite powder. Step 3: Add 7.5% by mass of nano-carbon black with an average particle size of 30 nm and a carbon content greater than 98% to the nano-zirconium carbide-tungsten trioxide composite powder obtained in Step 2, mix evenly, and then carry out carbothermic pre-reduction at 1050℃ for 2 h to obtain pre-reduced powder. Step 4: After spreading the pre-reduced powder obtained in Step 3, reduce it with hydrogen at 750℃ for 2 hours to finally obtain nano-tungsten-based composite powder with uniformly doped carbide particles.

[0027] Testing revealed that the average particle size of the uniformly doped carbide nano-tungsten-based composite powder prepared in this embodiment was approximately 88 nm; the average particle size of the dispersed carbide particles was approximately 15 nm.

[0028] Example 3 This embodiment includes the following steps: Step 1: Place tungsten trioxide with an average grain size of less than 90 nm in 70% ethanol by weight of tungsten trioxide and add 0.5% polyethylene glycol by weight of tungsten trioxide. Then ball mill at 250 r / min for 4 h and dry to obtain pretreated tungsten source powder. Step 2: Mix 0.4g of zirconium carbide nanoparticles with an average particle size of 50nm with 0.05g of polyethylene glycol and polyvinylpyrrolidone. Under continuous stirring and ultrasonic treatment, a uniformly dispersed zirconium carbide nanoparticle suspension is obtained. Then, 65g of the pretreated tungsten source powder obtained in Step 1 is added to the zirconium carbide nanoparticle suspension. After that, the mixture is ball-milled at a speed of 200r / min and dried to obtain a uniformly dispersed zirconium carbide-tungsten trioxide composite powder. Step 3: Add 7.5% by mass of nano-carbon black with an average particle size of 25 nm and a carbon content greater than 98% to the nano-zirconium carbide-tungsten trioxide composite powder obtained in Step 2, mix evenly, and then keep at 1000℃ for 3 h for carbothermal pre-reduction to obtain pre-reduced powder. Step 4: After spreading the pre-reduced powder obtained in Step 3, reduce it with hydrogen at 850℃ for 2 hours to finally obtain nano-tungsten-based composite powder with uniformly doped carbide particles.

[0029] Testing revealed that the average particle size of the uniformly doped carbide nano-tungsten-based composite powder prepared in this embodiment was approximately 90 nm; the average particle size of the dispersed carbide particles was approximately 20 nm.

[0030] Example 4 This embodiment includes the following steps: Step 1: Place tungsten trioxide with an average grain size of less than 100 nm in 50% ethanol and add 0.6% polyethylene glycol by weight of tungsten trioxide. Then ball mill at 200 r / min for 2 h and dry to obtain pretreated tungsten source powder. Step 2: Mix 0.5g of zirconium carbide nanoparticles with an average particle size of 60nm with 0.1g of polyvinylpyrrolidone. Under continuous stirring and ultrasonic treatment, a uniformly dispersed zirconium carbide nanoparticle suspension is obtained. Then, 50g of the pretreated tungsten source powder obtained in Step 1 is added to the zirconium carbide nanoparticle suspension. After that, the mixture is ball-milled at a speed of 250r / min and dried to obtain a uniformly dispersed zirconium carbide-tungsten trioxide composite powder. Step 3: Add 10% by mass of nano-carbon black with an average particle size of 30 nm and a carbon content greater than 98% to the nano-zirconium carbide-tungsten trioxide composite powder obtained in Step 2, mix evenly, and then keep at 1050℃ for 4 h for carbothermal pre-reduction to obtain pre-reduced powder. Step 4: After spreading the pre-reduced powder obtained in Step 3, reduce it with hydrogen at 850℃ for 4 hours to finally obtain nano-tungsten-based composite powder with uniformly doped carbide particles.

[0031] Testing revealed that the average particle size of the uniformly doped carbide nano-tungsten-based composite powder prepared in this embodiment was approximately 96 nm; the average particle size of the dispersed carbide particles was approximately 25 nm.

[0032] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention in any way. Any simple modifications, alterations, and equivalent changes made to the above embodiments based on the inventive essence shall still fall within the protection scope of the present invention.

Claims

1. A method for preparing tungsten-based nanoparticle composite powder doped with carbide particles, characterized in that, The method includes the following steps: Step 1: Place tungsten trioxide in a solvent and add a dispersant, then ball mill and disperse it evenly. After drying, obtain pretreated tungsten source powder. Step 2: The nano carbide particles are dispersed and surface modified with the aid of a dispersant, and then mixed with the pretreated tungsten source powder obtained in Step 1. After low-energy ball milling and drying, uniformly dispersed nano zirconium carbide-tungsten trioxide composite powder is obtained. Step 3: Mix the nano-zirconium carbide-tungsten trioxide composite powder obtained in Step 2 with carbon nanoparticles evenly, and then perform carbothermic pre-reduction by heating and heat preservation to obtain pre-reduced powder. Step 4: After spreading the pre-reduced powder obtained in Step 3, hydrogen reduction is carried out to finally obtain nano-tungsten-based composite powder with uniformly doped carbide particles.

2. The method for preparing tungsten-based nanoparticle-doped composite powder according to claim 1, characterized in that, The average grain size of tungsten trioxide mentioned in step one is less than 100 nm.

3. The method for preparing tungsten-based nanoparticle-doped composite powder according to claim 1, characterized in that, In step one, the solvent is ethanol, the dispersant is polyethylene glycol, the mass of the solvent is 50% to 70% of the mass of tungsten trioxide, the mass of the dispersant is 0.3% to 0.6% of the mass of tungsten trioxide, the ball milling speed is 200 r / min to 300 r / min, and the time is 2 h to 6 h.

4. The method for preparing tungsten-based nanoparticle composite powder doped with carbide particles according to claim 1, characterized in that, The nano carbide particles mentioned in step two are zirconium carbide nanoparticles with an average particle size of no more than 50 nm.

5. The method for preparing nano-tungsten-based composite powder doped with carbide particles according to claim 1, characterized in that, The dispersant in step two is polyethylene glycol and / or polyvinylpyrrolidone, the mass ratio of the nano-carbide particles to the dispersant is 0.4~0.5:0.05~0.2, and the dispersion and surface modification are performed by ultrasonic treatment.

6. The method for preparing tungsten-based nanoparticle composite powder doped with carbide particles according to claim 1, characterized in that, In step two, the mass ratio of the nano-carbide particles to the pretreated tungsten source powder is 0.4~0.5:50~65.

7. The method for preparing tungsten-based nanoparticle-doped composite powder according to claim 1, characterized in that, The carbon nanoparticles mentioned in step three are nano-carbon black with an average particle size of no more than 50 nm and a carbon mass content of more than 98%.

8. The method for preparing nano-tungsten-based composite powder doped with carbide particles according to claim 1, characterized in that, The mass of the carbon nanoparticles mentioned in step three is 5% to 10% of the mass of the nano-zirconium carbide-tungsten trioxide composite powder.

9. The method for preparing tungsten-based nanoparticle composite powder doped with carbide particles according to claim 1, characterized in that, The temperature for the carbothermic pre-reduction in step three is 950℃~1050℃, and the holding time is 2h~4h.

10. The method for preparing tungsten-based nanoparticle composite powder doped with carbide particles according to claim 1, characterized in that, The hydrogen reduction temperature in step four is 750℃~900℃, and the holding time is 1h~4h.

Images