A method for producing a high-performance tungsten or molybdenum alloy

Abstract

The application relates to a preparation method of high-performance tungsten alloy or molybdenum alloy. Carbide and didodecyldimethylammonium chloride are dispersed in ethanol to form sol system A; the sol system A is mixed with a tungsten salt aqueous solution or a molybdenum salt aqueous solution, heated and stirred after pH is adjusted to 4-6 to form sol system B with high dispersity; a crosslinking agent is added to the sol system B for gelation treatment to obtain a gel; the gel is vacuum dried to obtain precursor powder; the precursor powder is calcined and high-speed crushed, then hydrogen reduction is carried out to obtain core-shell structure carbide@tungsten powder or core-shell structure carbide@molybdenum powder; the powder is pressed into a compact, then high-temperature sintering is carried out to obtain high-performance tungsten alloy or molybdenum alloy. The application is controllable, simple and can regulate the content (0.05-5%) of the carbide in the tungsten alloy or molybdenum alloy, solves the problems that the second phase particle size, dispersity and structure are difficult to regulate in the traditional tungsten alloy or molybdenum alloy preparation process, and the comprehensive performance of the alloy is poor.

Description

Technical Field

[0001] This invention belongs to the field of alloy material preparation technology, specifically a method for preparing high-performance tungsten alloys or molybdenum alloys. Background Technology

[0002] Tungsten and molybdenum alloys possess excellent properties such as high density and melting point, high strength and elastic modulus, low coefficient of thermal expansion, and good corrosion resistance, making them widely used in aerospace, nuclear energy, electronics, metallurgy, and chemical industries. However, tungsten and molybdenum alloys also have drawbacks such as low recrystallization temperature, low toughness, high low-temperature brittleness, radiation hardening, and embrittlement. These limitations prevent them from meeting the demanding requirements of high-performance tungsten and molybdenum alloys in harsh working conditions in civilian and other fields, thus restricting their application and promotion in these areas.

[0003] Currently, effective methods to address this problem include second-phase dispersion strengthening and grain refinement. Adding carbides such as zirconium, titanium, and hafnium to tungsten or molybdenum alloys can significantly refine tungsten or molybdenum grains. This grain refinement and uniform dispersion of carbides within the grains greatly increase the recrystallization temperature of the tungsten or molybdenum alloys, improving their strength, toughness, wear resistance, and thermal stability, thus meeting stringent service requirements. However, traditional solid-solid mixing and solid-liquid mixing methods result in problems with controlling the particle size, morphology, and uniformity of the raw tungsten or molybdenum powders and second-phase particles. The alloys still exhibit severe second-phase agglomeration and poor dispersion. This leads to a situation where, although the strength of carbide-doped tungsten or molybdenum alloys is improved, their toughness is lower than that of pure tungsten or pure molybdenum. How to prepare highly dispersed carbide-doped tungsten composite powder to obtain high-strength and high-toughness tungsten alloys, or how to prepare highly dispersed carbide-doped molybdenum composite powder to obtain high-strength and high-toughness molybdenum alloys, remains an urgent problem to be solved. Summary of the Invention

[0004] The purpose of this invention is to provide a method for preparing high-performance tungsten or molybdenum alloys. The core-shell structured carbide@tungsten powder or core-shell structured carbide@molybdenum powder prepared by this method exhibits good dispersion and high sintering activity. Consequently, the prepared tungsten or molybdenum alloys have fine and uniform grains, high density, and uniform carbide particle distribution, resulting in multiple strengthening effects. This invention allows for the control of carbide content in tungsten or molybdenum alloys, solving the problem of poor overall alloy performance caused by the difficulty in controlling the dispersion and structure of the second phase in traditional tungsten or molybdenum alloy preparation processes.

[0005] This invention is specifically achieved through the following technical solution: a method for preparing a high-performance tungsten alloy according to this invention includes the following steps:

[0006] 1) Disperse carbide particles (MeC) and dioctadecyl dimethyl ammonium chloride in ethanol to form a stable sol system A, and prepare an aqueous solution of tungsten salt using water as a solvent;

[0007] The carbide mentioned in this step is selected from any one or more of zirconium carbide, hafnium carbide, and titanium carbide, and the tungsten salt is selected from any one or more of sodium tungstate, ammonium metatungstate, potassium tungstate, and ammonium paratungstate, and the concentration of tungsten ions in the tungsten salt aqueous solution is 2-7 mol / L.

[0008] 2) Mix the tungsten salt aqueous solution prepared in step 1) with the prepared sol system A at a volume ratio of 5:1 and stir until homogeneous. Adjust the pH of the mixture to 4-6 with an acid solution. Heat and stir at 60℃-85℃ for 0.5-2.5h to form a highly dispersed sol system B. Add a crosslinking agent to sol system B and perform gelation treatment for 1-4h to obtain a gel, thereby achieving uniform mixing and high dispersion of carbide particles and tungsten source.

[0009] The crosslinking agent mentioned in this step is selected from any one or more of polypropylene glycol glycidyl ether, tetraisocyanate, and trimethylolpropane;

[0010] 3) The gel from step 2) is vacuum dried at 80-120℃ for 4-8 hours to obtain precursor powder;

[0011] 4) The precursor powder obtained in step 3) is calcined in air at 400-600℃ for 2-5 hours, cooled to room temperature, and then subjected to high-speed pulverization to obtain powder with good dispersibility and high porosity; the powder is then subjected to two-stage hydrogen reduction to obtain core-shell structured carbide@tungsten powder.

[0012] 5) Press the core-shell structured carbide@tungsten powder obtained in step 4) into a green compact. The pressing pressure is 150-200 MPa, and the holding time is 20-40 min. Then, sinter it in a hydrogen atmosphere at a temperature of 1800-2300℃ for 6-14 h with a hydrogen flow rate of 8-15 m³ / h. 3 / h, ultimately producing a high-performance tungsten alloy.

[0013] Preferably, the concentration of the carbide in step 1) in sol system A is 0.024-0.7 mol / L; and the concentration of bis(octadecyl)dimethylammonium chloride in sol system A is 10-50 mmol / L.

[0014] Preferably, in step 2), the acid solution used to adjust the pH is phosphoric acid with a concentration of 0.5-2 mol / L, the concentration of the crosslinking agent is preferably 30-55 mmol / L, and the volume ratio of the crosslinking agent to the sol system B is 1:10 to 1:1000.

[0015] Preferably, in step 4), the high-speed pulverization speed of the pulverizer is 32000 r / min, and the time is 30-80 s.

[0016] Preferably, in step 4), the hydrogen reduction temperature is 450-660℃, the time is 0.5-8h, and the hydrogen flow rate is 14m³ / h. 3 / h~18m 3 / h, powder spreading height ≤2 / 3; second-stage hydrogen reduction temperature is 800-960℃, time is 2-5h, hydrogen flow rate is 15m³ / h. 3 / h~20m 3 / h, powder spreading height ≤2 / 3.

[0017] The core-shell structured carbide@tungsten powder prepared according to the above method has a particle size of 0.1-7 μm. The carbide is at least one of zirconium carbide, hafnium carbide, and titanium carbide, and the carbide accounts for 0.05-5% of the mass of the core-shell structured carbide@tungsten powder, with the balance being tungsten.

[0018] The high-performance tungsten alloy prepared according to the above method has a density of over 98.6%, a fracture grain size of 1-20 μm, a hardness of 200-400 HV, and a recrystallization temperature exceeding 1400℃. The high-performance tungsten alloy exhibits a room temperature tensile strength of over 1350 MPa and an elongation of over 20%, while its high-temperature tensile strength at 1200℃ reaches 500-800 MPa and an elongation of over 30%.

[0019] This invention also provides a method for preparing a high-performance molybdenum alloy, the preparation process of which is the same as that of the high-performance tungsten alloy described above, except that: the tungsten salt aqueous solution in step 1) of the aforementioned method is replaced with a molybdenum salt aqueous solution, wherein the molybdenum salt is selected from any one or more of sodium molybdate, ammonium metamolybdate, potassium molybdate, and ammonium paramolybdate, and the concentration of molybdenum ions in the molybdenum salt aqueous solution is 2-7 mol / L; after adding the crosslinking agent in step 2) of the aforementioned method, a gelation treatment is performed for 1-4 hours to obtain a gel, which achieves uniform mixing and high dispersion of carbide particles and molybdenum source; after two-stage hydrogen reduction in step 4), a core-shell structured carbide@molybdenum powder is obtained; in step 5), the obtained core-shell structured carbide@molybdenum powder is pressed into a green blank and sintered in a hydrogen atmosphere to finally obtain the high-performance molybdenum alloy described above.

[0020] Furthermore, the particle size of the core-shell structured carbide@molybdenum powder prepared according to the aforementioned method is 0.1-7 μm, the carbide is at least one of zirconium carbide, hafnium carbide, and titanium carbide, and the carbide accounts for 0.05-5% of the mass of the core-shell structured carbide@molybdenum powder, with the balance being molybdenum.

[0021] Furthermore, the high-performance molybdenum alloy prepared according to the aforementioned method has a density of over 99%, a fracture grain size of 1-20 μm, a hardness of 200-400 HV, and a recrystallization temperature exceeding 1300℃; the high-performance molybdenum alloy has a room temperature tensile strength of over 900 MPa and an elongation of over 40%, and a high-temperature tensile strength of over 200 MPa and an elongation of over 30% at 1200℃.

[0022] The tungsten and molybdenum alloys prepared above can meet the requirements of use under harsh working conditions and are commonly used as materials for high-temperature refractory structural components and high-radiation protection materials.

[0023] Compared with existing technologies, this invention has significant advantages and beneficial effects. Through the above technical solution, this invention achieves considerable technological advancement and practicality, and has broad application value, possessing at least the following advantages:

[0024] (1) This invention utilizes a two-phase water-oil system to achieve high solvent dispersion of carbide (MeC) particles. By adjusting the pH and heating and stirring, a highly dispersed sol system is formed. By adding a crosslinking agent to the sol system, gelation treatment is performed to form MeC@RN. + —WO4 2- Or MeC@RN + —MoO4 2- The gel structure allows for high dispersion and uniform mixing of carbide particles with the tungsten or molybdenum source, preventing agglomeration and powder clustering of tungsten or molybdenum particles during subsequent hydrogen reduction, thus significantly improving the dispersibility and stability of the tungsten or molybdenum particles. By adjusting the calcination and hydrogen reduction process parameters, carbide@tungsten powder or carbide@molybdenum powder with a core-shell structure is prepared. Finally, high-performance carbide-reinforced tungsten alloys or carbide-reinforced molybdenum alloys are prepared through compaction and high-temperature sintering. This invention achieves uniform dispersion of carbide particles in tungsten or molybdenum alloys, exerting multiple strengthening effects. The alloy strength is more than twice that of pure tungsten or pure molybdenum, the toughness is no less than that of pure tungsten or pure molybdenum, and the recrystallization temperature is increased by 300-600℃, meeting the requirements for use under harsh conditions such as ultra-high temperature (above 1300℃) and strong radiation.

[0025] (2) In the hydrogen reduction process of this invention, the highly dispersed and high-porosity powder structure promotes the rapid diffusion of hydrogen and water vapor products, effectively controlling the growth and agglomeration of powder particles. Simultaneously, this structure provides favorable conditions for the gas-phase migration and nucleation growth of tungsten (molybdenum) hydrated oxides, promoting the growth of tungsten (molybdenum) on carbide nuclei. This allows for the controlled preparation of unique core-shell structured carbide@tungsten powder or core-shell structured carbide@molybdenum powder. The prepared core-shell structured carbide@tungsten powder or core-shell structured carbide@molybdenum powder exhibits good dispersion and high sintering activity. Consequently, the prepared tungsten alloy or molybdenum alloy has fine and uniform grains, high density, and uniform carbide particle distribution, resulting in multiple strengthening effects and significantly improving the performance of the tungsten alloy or molybdenum alloy.

[0026] (3) The process of this invention is controllable, the method is simple and easy to operate. It can control the content and uniform distribution of grains and second phase carbides in tungsten alloys or molybdenum alloys, and solve the problem of poor overall performance of the alloy due to the difficulty in controlling the uniform distribution and structure of the second phase in the traditional tungsten alloy or molybdenum alloy preparation process. Attached Figure Description

[0027] Figure 1 These are low-magnification SEM images (a) and high-magnification SEM images (b) of the core-shell structured hafnium carbide@tungsten powder prepared in Example 1;

[0028] Figure 2 Here is a SEM image of the fracture surface of the high-performance tungsten alloy prepared in Example 1;

[0029] Figure 3 Here is a SEM image of the core-shell structured zirconium carbide@molybdenum powder prepared in Example 3;

[0030] Figure 4 Here is a SEM image of the fracture surface of the high-performance molybdenum alloy prepared in Example 3;

[0031] Figure 5 The room temperature stress-strain curves are those of the high-performance tungsten alloy prepared in Example 2 and the high-performance molybdenum alloy prepared in Example 4, as well as pure tungsten and pure molybdenum.

[0032] Figure 6 These are the high-temperature stress-strain curves at 1200℃ for pure tungsten and the tungsten alloy prepared in Example 1;

[0033] Figure 7 These are the high-temperature stress-strain curves at 1200℃ for pure molybdenum and the molybdenum alloy prepared in Example 3. Detailed Implementation

[0034] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below in conjunction with specific embodiments. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0035] Example 1

[0036] 1) 0.005 mol hafnium carbide and 1 mmol dioctadecyl dimethyl ammonium chloride were dispersed in 50 mL of ethanol to form a stable sol system A, which made the hafnium carbide particles highly dispersed and greatly improved the surface activity. The concentration of hafnium carbide in sol system A was 0.1 mol / L and the concentration of dioctadecyl dimethyl ammonium chloride was 20 mmol / L. A 4 mol / L tungsten salt aqueous solution was prepared using water as solvent. Sodium tungstate was selected as the tungsten salt.

[0037] 2) Mix the tungsten salt aqueous solution prepared in step 1) with the prepared sol system A at a volume ratio of 5:1, stir until homogeneous, adjust the pH of the mixture to approximately 4.5 using a 1 mol / L phosphoric acid solution, and heat and stir at 65°C for 1 hour to form a highly dispersed sol system B. Add 30 mmol / L trimethylolpropane to sol system B and perform gelation treatment for 2 hours to obtain a gel. The volume ratio of trimethylolpropane to sol system B is 1:10.

[0038] 3) The gel from step 2) was vacuum dried at 90°C for 6 hours to obtain the precursor powder.

[0039] 4) The precursor powder obtained in step 3) was calcined in air at 400℃ for 4 hours, cooled to room temperature, and then subjected to high-speed pulverization at a speed of 32,000 rpm for 40 seconds to obtain powder with good dispersion and high porosity; the powder was then subjected to two-stage hydrogen reduction to obtain core-shell structured hafnium carbide@tungsten powder.

[0040] One stage of hydrogen reduction involved a temperature of 450℃, a duration of 4 hours, and a hydrogen flow rate of 14 m³ / h. 3 / h, powder spreading height ≤2 / 3; second-stage hydrogen reduction temperature is 850℃, time is 3h, hydrogen flow rate is 20m³ / h. 3 / h, powder spreading height ≤2 / 3.

[0041] The obtained core-shell structured hafnium carbide@tungsten powder contains 0.5% hafnium carbide by mass, with the remainder being tungsten.

[0042] 5) The core-shell structured hafnium carbide@tungsten powder obtained in step 4) was cold isostatically pressed into a green compact at a pressure of 150 MPa and a holding time of 30 min; then sintered in a hydrogen atmosphere at a temperature of 1800℃ and a holding time of 6 h, with a hydrogen flow rate of 15 m³ / h. 3 / h, ultimately producing a high-performance tungsten alloy.

[0043] Figure 1 These are low-magnification SEM images (a) and high-magnification SEM images (b) of the core-shell structured hafnium carbide@tungsten powder prepared in this embodiment. Figure 1 As shown in (a), the core-shell structured hafnium carbide@tungsten powder is nearly spherical with a particle size of 0.1-2 μm; Figure 1 As shown in (b), hafnium carbide@tungsten powder has a core-shell structure.

[0044] Figure 2 These are SEM images of the fracture surface of the prepared high-performance tungsten alloy. Figure 2 It is known that fine hafnium carbide particles are dispersed inside tungsten grains, which can hinder grain growth, refine grains, and play a role in grain refinement and strengthening. At the same time, the nano hafnium carbide particles distributed inside the grains hinder dislocation migration, increase the recrystallization temperature of tungsten alloys, and improve their room temperature and high temperature strength.

[0045] Example 2

[0046] 1) 0.035 mol of titanium carbide and 2.5 mmol of dioctadecyl dimethyl ammonium chloride were dispersed in 50 mL of ethanol to form a stable sol system A, which made the titanium carbide particles highly dispersed and greatly improved the surface activity. The concentration of titanium carbide in sol system A was 0.7 mol / L and the concentration of dioctadecyl dimethyl ammonium chloride was 50 mmol / L. A 3 mol / L tungsten salt aqueous solution was prepared using water as solvent. Ammonium paratungstate was selected as the tungsten salt.

[0047] 2) Mix the tungsten salt aqueous solution prepared in step 1) with the prepared sol system A at a volume ratio of 5:1, stir until homogeneous, adjust the pH of the mixture to approximately 6 using a 0.5 mol / L phosphoric acid solution, and heat and stir at 70°C for 1.5 h to form a highly dispersed sol system B. Add 40 mmol / L polypropylene glycol glycidyl ether to sol system B and perform gelation treatment for 4 h to obtain a gel. The volume ratio of polypropylene glycol glycidyl ether to sol system B is 1:10.

[0048] 3) The gel from step 2) was vacuum dried at 100°C for 5 hours to obtain the precursor powder.

[0049] 4) The precursor powder obtained in step 3) was calcined in air at 600℃ for 3 hours, cooled to room temperature, and then subjected to high-speed pulverization at a speed of 32,000 rpm for 30 seconds. This yielded a powder with good dispersibility and high porosity. The powder was then subjected to two-stage hydrogen reduction to obtain core-shell structured titanium carbide@tungsten powder.

[0050] One stage of hydrogen reduction involved a temperature of 550℃, a duration of 5 hours, and a hydrogen flow rate of 18 m³ / h. 3 / h, powder spreading height ≤2 / 3; second-stage hydrogen reduction temperature is 920℃, time is 3.5h, hydrogen flow rate is 18m³ / h. 3 / h, powder spreading height ≤2 / 3.

[0051] The obtained core-shell structured titanium carbide@tungsten powder contains 1.5% titanium carbide by mass, with the remainder being tungsten.

[0052] 5) The core-shell structured titanium carbide@tungsten powder obtained in step 4) was cold isostatically pressed into a green compact at a pressure of 200 MPa and a holding time of 20 min; then sintered in a hydrogen atmosphere at a temperature of 1900℃ and a holding time of 6 h, with a hydrogen flow rate of 10 m³ / h. 3 / h, ultimately producing a high-performance tungsten alloy.

[0053] Example 3

[0054] 1) Disperse 0.012 mol zirconium carbide and 2 mmol bis(octadecyl)dimethylammonium chloride in 50 mL ethanol to form a stable sol system A, which makes the zirconium carbide particles highly dispersed; the concentration of zirconium carbide in sol system A is 0.24 mol / L and the concentration of bis(octadecyl)dimethylammonium chloride is 40 mmol / L. Prepare a 5 mol / L aqueous solution of molybdenum salt using water as solvent. Sodium molybdate is selected as the molybdenum salt.

[0055] 2) Mix the molybdenum salt aqueous solution prepared in step 1) with the prepared sol system A at a volume ratio of 5:1, stir until homogeneous, adjust the pH of the mixture to approximately 5 using a 2 mol / L phosphoric acid solution, and heat and stir at 85°C for 2 hours to form a highly dispersed sol system B. Add 55 mmol / L trimethylolpropane to sol system B and perform gelation treatment for 3 hours to obtain a gel. The volume ratio of trimethylolpropane to sol system B is 1:10.

[0056] 3) The gel from step 2) was vacuum dried at 120°C for 4 hours to obtain the precursor powder.

[0057] 4) The precursor powder obtained in step 3) was calcined in air at 450℃ for 4 hours, cooled to room temperature, and then subjected to high-speed pulverization at a speed of 32,000 rpm for 50 seconds. This yielded a powder with good dispersibility and high porosity. The powder was then subjected to two-stage hydrogen reduction to obtain core-shell structured zirconium carbide@molybdenum powder.

[0058] One stage of hydrogen reduction involves a temperature of 500℃, a duration of 4 hours, and a hydrogen flow rate of 15m³. 3 / h, powder spreading height ≤2 / 3; second-stage hydrogen reduction temperature is 800℃, time is 5h, hydrogen flow rate is 15m³ / h. 3 / h, powder spreading height ≤2 / 3.

[0059] The obtained core-shell structured zirconium carbide@molybdenum powder contains 1.0% zirconium carbide by mass, with the remainder being molybdenum.

[0060] 5) The core-shell structured zirconium carbide@molybdenum powder obtained in step 4) was cold isostatically pressed into a green compact at a pressure of 180 MPa and a holding time of 20 min; then sintered in a hydrogen atmosphere at a temperature of 1850 °C and a holding time of 7 h, with a hydrogen flow rate of 15 m³ / h. 3 / h, ultimately producing a high-performance molybdenum alloy.

[0061] Figure 3 This is a SEM image of the core-shell structured zirconium carbide@molybdenum powder prepared in this embodiment. Figure 3 It can be seen that the powder particles are uniform in size, nearly spherical, and have an average particle size of 0.1-2μm.

[0062] Figure 4 This is a SEM image of the fracture surface of the high-performance molybdenum alloy prepared in this embodiment. Figure 4 It is known that zirconium carbide particles are dispersed inside the molybdenum grains, hindering grain growth and refining the grains. The nano-zirconium carbide particles distributed inside the grains hinder dislocation migration and play a role in grain refinement and strengthening, thereby improving its room temperature and high temperature strength.

[0063] Example 4

[0064] 1) Disperse 0.0012 mol hafnium carbide and 1.5 mmol dioctadecyl dimethyl ammonium chloride in 50 mL ethanol to form a stable sol system A, which makes the hafnium carbide particles highly dispersed; the concentration of hafnium carbide in sol system A is 0.024 mol / L, the concentration of dioctadecyl dimethyl ammonium chloride is 30 mmol / L, and a 3 mol / L molybdenum salt aqueous solution is prepared using water as solvent, and ammonium paramolybdate is selected as the molybdenum salt.

[0065] 2) Mix the molybdenum salt aqueous solution prepared in step 1) with the prepared sol system A at a volume ratio of 5:1, stir until homogeneous, adjust the pH of the mixture to approximately 5 using a 1 mol / L phosphoric acid solution, and heat and stir at 85°C for 2 hours to form a highly dispersed sol system B. Add 50 mmol / L tetraisocyanate to sol system B and perform gelation treatment for 3 hours to obtain a gel. The volume ratio of tetraisocyanate to sol system B is 1:10.

[0066] 3) The gel from step 2) was vacuum dried at 100°C for 4 hours to obtain the precursor powder.

[0067] 4) The precursor powder obtained in step 3) was calcined in air at 500℃ for 4 hours, cooled to room temperature, and then subjected to high-speed pulverization at a speed of 32,000 rpm for 60 seconds. This yielded a powder with good dispersibility and high porosity. The powder was then subjected to two-stage hydrogen reduction to obtain core-shell structured hafnium carbide@molybdenum powder.

[0068] One stage of hydrogen reduction involves a temperature of 600℃, a duration of 3 hours, and a hydrogen flow rate of 15m³ / h. 3 / h, powder spreading height ≤2 / 3; second-stage hydrogen reduction temperature is 860℃, time is 4h, hydrogen flow rate is 15m³ / h. 3 / h, powder spreading height ≤2 / 3.

[0069] The obtained core-shell structured hafnium carbide@molybdenum powder contains 0.3% hafnium carbide by mass, with the remainder being molybdenum.

[0070] 5) The core-shell structured hafnium@molybdenum carbide powder obtained in step 4) was cold isostatically pressed into a green compact at a pressure of 150 MPa and a holding time of 40 min; then sintered in a hydrogen atmosphere at a temperature of 1950 °C and a holding time of 7 h, with a hydrogen flow rate of 15 m³ / h. 3 / h, ultimately yielding a high-performance molybdenum alloy.

[0071] Figure 5 These are the room temperature stress-strain curves of the high-performance tungsten alloy prepared in Example 2, the high-performance molybdenum alloy prepared in Example 4, and pure tungsten and pure molybdenum. Figure 5 It is known that the tensile strength of tungsten alloys with the addition of titanium carbide is nearly 600 MPa higher than that of pure tungsten, and the elongation is more than doubled. The tensile strength of molybdenum alloys with the addition of hafnium carbide is nearly 600 MPa higher than that of pure molybdenum, and the room temperature elongation is more than 25% higher. Therefore, this invention solves the problem of reduced elongation after adding carbides to tungsten or molybdenum alloys using traditional methods.

[0072] Figure 6 These are the high-temperature stress-strain curves at 1200℃ for pure tungsten and the high-performance tungsten alloy prepared in Example 1. Figure 6It can be seen that the high-temperature tensile strength and high-temperature elongation of tungsten alloys with the addition of hafnium carbide are more than twice that of pure tungsten.

[0073] Figure 7 These are the high-temperature stress-strain curves at 1200℃ for pure molybdenum and the molybdenum alloy prepared in Example 3. Figure 7 It can be seen that the high-temperature tensile strength of the molybdenum alloy with the addition of zirconium carbide is more than twice that of pure molybdenum, and the high-temperature elongation is more than 50% higher than that of pure molybdenum.

[0074] The room temperature mechanical properties of the high-performance tungsten alloys or high-performance molybdenum alloys prepared in Examples 1-4 were tested using an INSTRON-5967 universal testing machine (USA), and the high temperature tensile strength of the high-performance tungsten alloys or high-performance molybdenum alloys prepared in Examples 1-4 was tested using a Gleeble-1500 thermal simulation testing machine. The results are shown in Table 1 below:

[0075] Table 1. Properties of the high-performance tungsten alloys or high-performance molybdenum alloys prepared in Examples 1-4

[0076]

[0077]

[0078] The above description is merely an embodiment of the present invention and is not intended to limit the present invention in any way. The present invention can also have other embodiments based on the above structure and function, which will not be listed hereafter. Therefore, any simple modifications, equivalent changes, and alterations made by those skilled in the art to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A method for preparing high-performance tungsten alloys, characterized in that... Includes the following steps: 1) Disperse the carbide and dioctadecyldimethylammonium chloride in ethanol to form a stable sol system A, and prepare an aqueous solution of tungsten salt using water as a solvent; The carbide mentioned in this step is selected from any one or more of zirconium carbide, hafnium carbide, and titanium carbide, and the tungsten salt is selected from any one or more of sodium tungstate, ammonium metatungstate, potassium tungstate, and ammonium paratungstate, and the concentration of tungsten ions in the tungsten salt aqueous solution is 2-7 mol / L. 2) Mix the tungsten salt aqueous solution prepared in step 1) with the prepared sol system A at a volume ratio of 5:1, stir evenly, adjust the pH of the mixture to 4-6 with acid solution, heat and stir at 60℃-85℃ for 0.5-2.5h to form a highly dispersed sol system B, add a crosslinking agent to sol system B and perform gelation treatment for 1-4h to obtain a gel. The crosslinking agent mentioned in this step is selected from any one or more of polypropylene glycol glycidyl ether, tetraisocyanate, and trimethylolpropane; 3) The gel obtained in step 2) is vacuum dried at 80-120℃ for 4-8 hours to obtain precursor powder; 4) The precursor powder obtained in step 3) is calcined in air at 400-600℃ for 2-5 hours, cooled to room temperature, and then pulverized at high speed. The pulverized powder is then subjected to two-stage hydrogen reduction to obtain core-shell structured carbide@tungsten powder. 5) Press the core-shell structured carbide@tungsten powder obtained in step 4) into a green compact. The pressing pressure is 150-200 MPa, and the holding time is 20-40 min. Then, sinter it in a hydrogen atmosphere at a temperature of 1800-2300℃ for 6-14 h with a hydrogen flow rate of 8-15 m³ / h. 3 / h, ultimately producing a high-performance tungsten alloy.

2. The method for preparing high-performance tungsten alloy as described in claim 1, characterized in that... The concentration of the carbide in step 1) in sol system A is 0.024-0.7 mol / L; the concentration of dioctadecyl dimethyl ammonium chloride in sol system A is 10-50 mmol / L.

3. The method for preparing high-performance tungsten alloy as described in claim 1, characterized in that... In step 2), the acid solution used to adjust the pH is phosphoric acid with a concentration of 0.5-2 mol / L, and the concentration of the crosslinking agent is 30-55 mmol / L.

4. The method for preparing high-performance tungsten alloy as described in claim 1, characterized in that... In step 4), the pulverizer speed is 32000 r / min and the time is 30-80 s during high-speed pulverization.

5. The method for preparing high-performance tungsten alloy as described in claim 1, characterized in that... In step 4), the hydrogen reduction temperature is 450-660℃, the time is 0.5-8h, and the hydrogen flow rate is 14m³ / h. 3 / h~18m 3 / h, powder spreading height ≤2 / 3; second-stage hydrogen reduction temperature is 800-960℃, time is 2-5h, hydrogen flow rate is 15m³ / h. 3 / h~20m 3 / h, powder spreading height ≤2 / 3.

6. The method for preparing high-performance tungsten alloy according to any one of claims 1-5, characterized in that... The particle size of the core-shell structured carbide@tungsten powder obtained in step 4) is 0.1-7 μm. The carbide is at least one of zirconium carbide, hafnium carbide, and titanium carbide, and the carbide accounts for 0.05-5% of the mass of the core-shell structured carbide@tungsten powder, with the balance being tungsten.

7. The method for preparing high-performance tungsten alloy according to any one of claims 1-5, characterized in that... The high-performance tungsten alloy prepared in step 5) has a density of over 98.6%, a fracture grain size of 1-20 μm, a hardness of 200-400 HV, and a recrystallization temperature of over 1400℃. The high-performance tungsten alloy has a room temperature tensile strength of over 1350 MPa and an elongation of over 20%, and a high temperature tensile strength of 500-800 MPa and an elongation of over 30% at 1200℃.

8. A method for preparing high-performance molybdenum alloys, characterized in that... According to the preparation method of any one of claims 1-5, the tungsten salt aqueous solution in step 1) is replaced with a molybdenum salt aqueous solution, wherein the molybdenum salt is selected from any one or more of sodium molybdate, ammonium metamolybdate, potassium molybdate, and ammonium paramolybdate, and the concentration of molybdenum ions in the molybdenum salt aqueous solution is 2-7 mol / L; after adding the crosslinking agent in step 2), a gelation treatment is performed for 1-4 hours to obtain a gel, thereby achieving uniform mixing and high dispersion of carbide particles and molybdenum source; after two-stage hydrogen reduction in step 4), core-shell structured carbide@molybdenum powder is obtained; after pressing the obtained core-shell structured carbide@molybdenum powder into a green body, it is sintered in a hydrogen atmosphere to finally obtain the high-performance molybdenum alloy.

9. The method for preparing high-performance molybdenum alloy as described in claim 8, characterized in that... The particle size of the core-shell structured carbide@molybdenum powder obtained in step 4) is 0.1-7 μm. The carbide is at least one of zirconium carbide, hafnium carbide, and titanium carbide, and the carbide accounts for 0.05-5% of the mass of the core-shell structured carbide@molybdenum powder, with the balance being molybdenum.

10. The method for preparing the high-performance molybdenum alloy as described in claim 8, characterized in that... The final high-performance molybdenum alloy has a density of over 99%, a fracture grain size of 1-20 μm, a hardness of 200-400 HV, and a recrystallization temperature exceeding 1300℃. The high-performance molybdenum alloy has a room temperature tensile strength of over 900 MPa and an elongation of over 40%, and a high-temperature tensile strength of over 200 MPa and an elongation of over 30% at 1200℃.

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