Rare earth oxide doped tungsten composite material and preparation method and application thereof

Abstract

The invention belongs to the technical field of tungsten and tungsten products, and particularly relates to a preparation method and application of a rare earth oxide doped tungsten composite material. A tungsten salt solution and a rare earth metal salt solution are dispersed and distributed in a high-temperature environment in a tiny suspension form in an atomization manner and are mixed with each other. Then, at a high temperature, liquid drops formed by mixing are rapidly dried and are subjected to pyrolytic reaction to form tungsten oxide and nano rare earth oxide. In the subsequent reduction reaction, tungsten oxide is reduced into tungsten powder, and the rare earth oxide retains the original components and structure and is uniformly distributed. The invention provides the method capable of efficiently and industrially preparing the uniform rare earth doped tungsten powder in a short process, ammonium paratungstate does not need to be produced, the influence of the genetic effect of ammonium paratungstate is reduced, the process steps are reduced, and the energy utilization rate is increased; the rare earth and the tungsten element are uniformly mixed in a liquid-liquid mixing mode, the tungsten powder uniformly doped with the rare earth is obtained through high-temperature rapid oxidation, and no waste liquid is generated in the production process.

Description

Technical Field

[0001] This invention belongs to the technical field of tungsten and tungsten products, specifically relating to a rare earth oxide-doped tungsten composite material, its preparation method, and its application. Background Technology

[0002] Doping rare earth elements into cemented carbide can significantly improve material properties, but the uneven distribution of rare earth elements is a problem that urgently needs to be solved. Tungsten powder is an important raw material for the preparation of tungsten carbide cemented carbide. It is usually prepared from ammonium tungstate solution through a series of processes including calcination, reduction, carbonization, pressing, and sintering. However, research has found that ammonium paratungstate exhibits a hereditary effect; that is, the particle size and morphology of ammonium paratungstate greatly affect the grain size and properties of the cemented carbide prepared after subsequent calcination and hydrogen reduction processes, including tungsten oxide powder, tungsten powder, and the resulting cemented carbide. Summary of the Invention

[0003] The purpose of this invention is to provide a rare earth oxide-doped tungsten composite material, its preparation method, and its application.

[0004] To achieve the above objectives, the present invention provides the following technical solution: This invention provides a method for preparing rare earth oxide-doped tungsten composite materials, comprising the following steps: Tungsten salt solution and rare earth metal salt solution are atomized separately. The droplets formed by atomization are combined and then pyrolyzed to obtain rare earth oxide-doped tungsten oxide. The ambient temperature of the pyrolysis is not lower than 700℃. The rare earth oxide-doped tungsten oxide was calcined in a reducing atmosphere to obtain a rare earth oxide-doped tungsten composite material.

[0005] Preferably, the tungsten salt solution includes at least one of ammonium tungstate solution and ammonium metatungstate solution.

[0006] Preferably, the WO3 content in the tungsten salt solution is 100~370g / L.

[0007] Preferably, the rare earth metal salt solution includes at least one of cerium salt solution, lanthanum salt solution, yttrium salt solution, and ytterbium salt solution.

[0008] Preferably, the content of rare earth metal salts in the rare earth metal salt solution is not higher than 10 g / L.

[0009] Preferably, the atomization conditions include: a gas-liquid ratio of not more than 2:1, a gas pressure of not more than 0.5 MPa, and a liquid pressure of not more than 0.6 MPa.

[0010] Preferably, the ambient temperature for atomization and pyrolysis is 700~900℃.

[0011] Preferably, the reducing atmosphere is hydrogen. The calcination temperature is 800~1000℃, and the holding time is no more than 2 hours.

[0012] The present invention also provides a rare earth oxide-doped tungsten composite material prepared by the preparation method described above, comprising a submicron-sized tungsten matrix and nano-sized rare earth oxides doped at the grain boundaries of the submicron-sized tungsten matrix.

[0013] The present invention also provides the application of the rare earth oxide-doped tungsten composite material described in the above technical solution in the preparation of alloys.

[0014] This invention provides a method for preparing rare earth oxide-doped tungsten composite material, comprising the following steps: atomizing a tungsten salt solution and a rare earth metal salt solution respectively, and then pyrolyzing the atomized droplets to obtain rare earth oxide-doped tungsten oxide; the pyrolysis environment temperature is not lower than 700℃; and calcining the rare earth oxide-doped tungsten oxide in a reducing atmosphere to obtain the rare earth oxide-doped tungsten composite material.

[0015] This invention proposes a method for the rapid preparation of tungsten-doped composite materials via pyrolysis spraying. Tungsten salt solution and rare earth metal salt solution are dispersed in a high-temperature environment through atomization, where they are mixed. Subsequently, at high temperature, the resulting droplets rapidly dry and undergo pyrolysis to form tungsten oxide, while the rare earth salts are transformed into nano-rare earth oxides. In the subsequent reduction reaction, the tungsten oxide is reduced to tungsten powder, while the rare earth oxides retain their original composition and structure, achieving uniform distribution. This invention aims to provide a highly efficient, industrially feasible, and rapid method for preparing uniform rare earth-doped tungsten powder. This method eliminates the need for the production of ammonium paratungstate intermediates, reducing the genetic effects of ammonium paratungstate, decreasing process steps, and improving energy utilization. Furthermore, it utilizes liquid-liquid mixing to achieve uniform mixing of rare earth and tungsten elements, followed by rapid high-temperature oxidation to obtain uniform rare earth-doped tungsten powder, with no waste liquid generated during the production process. Attached Figure Description

[0016] Figure 1 The morphology and EDS spectrum of rare earth oxide-doped tungsten oxide prepared by pyrolysis in Example 1; Figure 2 The XRD pattern of rare earth oxide-doped tungsten oxide prepared by pyrolysis in Example 1; Figure 3 The image shows the morphology of the rare earth oxide-doped tungsten composite material obtained in Example 1. Figure 4 The XRD pattern of the rare earth oxide-doped tungsten composite material obtained in Example 1 is shown below. Figure 5The fracture morphology of WC-6Co cemented carbide prepared from the rare earth oxide-doped tungsten composite material obtained in Example 1 is shown. Detailed Implementation

[0017] This invention provides a method for preparing rare earth oxide-doped tungsten composite materials, comprising the following steps: Tungsten salt solution and rare earth metal salt solution are atomized separately. The droplets formed by atomization are combined and then pyrolyzed to obtain rare earth oxide-doped tungsten oxide. The ambient temperature of the pyrolysis is not lower than 700℃. The rare earth oxide-doped tungsten oxide was calcined in a reducing atmosphere to obtain a rare earth oxide-doped tungsten composite material.

[0018] This invention involves atomizing tungsten salt solution and rare earth metal salt solution separately, and then pyrolyzing the resulting droplets to obtain rare earth oxide-doped tungsten oxide.

[0019] In this invention, the tungsten salt solution preferably includes at least one of ammonium tungstate solution and ammonium metatungstate solution. In this invention, the WO3 content in the tungsten salt solution is preferably 100~370 g / L, specifically 100 g / L, 150 g / L, 200 g / L, 250 g / L, 300 g / L, 350 g / L, or 370 g / L.

[0020] In this invention, the rare earth metal salt solution preferably includes at least one selected from cerium salt solution, lanthanum salt solution, yttrium salt solution, and ytterbium salt solution. In this invention, the content of rare earth metal salts in the rare earth metal salt solution is preferably not higher than 10 g / L, more preferably 0.5~10 g / L. In this invention, the cerium salt solution preferably includes cerium nitrate solution.

[0021] In this invention, the volume ratio of the tungsten salt solution to the rare earth metal salt solution is preferably 1:1.

[0022] In this invention, the preferred atomization conditions include: a gas-liquid ratio not exceeding 2:1, preferably 1.2 to 2:1; a gas pressure not exceeding 0.5 MPa, preferably 0.3 to 0.5 MPa; and a liquid pressure not exceeding 0.6 MPa, preferably 0.4 to 0.6 MPa. This invention does not impose any special limitations on the atomization process; any process well-known to those skilled in the art can be used. In a specific embodiment of this invention, the atomization is preferably performed using an air-assisted two-fluid spray nozzle. In this invention, the ambient temperature for atomization is the same as the ambient temperature for pyrolysis, and will not be described further here.

[0023] In this invention, the ambient temperature of the pyrolysis is not lower than 700°C, preferably 700~900°C, specifically 700°C, 800°C, or 900°C.

[0024] After obtaining the rare earth oxide-doped tungsten oxide, the present invention calcines the rare earth oxide-doped tungsten oxide in a reducing atmosphere to obtain a rare earth oxide-doped tungsten composite material.

[0025] In this invention, the reducing atmosphere is preferably hydrogen; the calcination temperature is preferably 800~1000℃, specifically 800℃, 900℃, or 1000℃; and the holding time is preferably no more than 2 hours, preferably 1.5~2 hours.

[0026] The present invention also provides a rare earth oxide-doped tungsten composite material prepared by the preparation method described above, comprising a submicron-sized tungsten matrix and nano-sized rare earth oxides doped at the grain boundaries of the submicron-sized tungsten matrix.

[0027] In this invention, the mass percentage of rare earth elements in the rare earth oxide-doped tungsten composite material is preferably no more than 3%.

[0028] The present invention also provides the application of the rare earth oxide-doped tungsten composite material described in the above technical solution in the preparation of alloys.

[0029] Unless otherwise specified, the materials and equipment used in this invention are all commercially available products in the field.

[0030] The technical solutions of this invention will be clearly and completely described below with reference to the embodiments thereof. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0031] Example 1 An ammonium tungstate aqueous solution (WO3 content 370 g / L) and a cerium nitrate solution (cerium nitrate content 0.5 g / L) with a volume ratio of 1:1 were atomized using an air-assisted two-fluid spray nozzle at an ambient temperature of 910℃. The resulting droplets were then pyrolyzed to obtain rare earth oxide-doped tungsten oxide. The gas-liquid ratio during atomization was 1.2:1, the gas pressure was 0.3 MPa, and the liquid pressure was 0.45 MPa. The rare earth oxide-doped tungsten oxide obtained was calcined at 850℃ in a hydrogen atmosphere for 1.5 h to obtain a rare earth oxide-doped tungsten composite material, wherein the mass percentage of cerium element was 0.25%.

[0032] Performance testing Test Example 1 Figure 1The images show the morphology and EDS spectrum of the rare earth oxide-doped tungsten oxide prepared by pyrolysis in Example 1. It can be seen that the prepared sample has a micron-sized spherical structure. Figure 2 The corresponding XRD patterns show that the powders prepared by this method have W3O8 and WO3 structures.

[0033] Figure 3 and Figure 4 The images show the morphology and XRD patterns of the rare earth oxide-doped tungsten composite material obtained in Example 1. Uniformly distributed nano-cerium oxide particles were found at the grain boundaries of the tungsten powder. In the corresponding XRD patterns, due to the low content of rare earth elements, no rare earth element-related phases were found.

[0034] Test Example 2 The rare earth oxide-doped tungsten composite material obtained in Example 1 was used to prepare WC-6.5Co cemented carbide; The specific process is as follows: the rare earth oxide-doped tungsten composite material is subjected to hydrogen reduction, carbonization and sintering in sequence. The hydrogen reduction temperature is 900℃ and the time is 1h; the carbonization temperature is 1400℃ and the time is 2h; the sintering temperature is 1410℃ and the time is 1h, and the pressure is 9MPa. The performance of the obtained WC-6.5Co cemented carbide was tested in accordance with GB / T385-12015. Figure 5 The fracture morphology of the prepared WC-6Co cemented carbide is shown in the figure. As can be seen from the figure, no obvious crack initiation or defects were found at the fracture surface. The WC-6Co cemented carbide has a bending strength of 3286 MPa, a hardness of 94.3 HRA, and a density of 14.68 g / cm³. 3 .

[0035] Although the above embodiments have provided a detailed description of the present invention, they are only some embodiments of the present invention, and not all embodiments. Other embodiments can be obtained based on these embodiments without creative effort, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A method for preparing a rare earth oxide-doped tungsten composite material, characterized in that, Includes the following steps: Tungsten salt solution and rare earth metal salt solution are atomized separately. The droplets formed by atomization are combined and then pyrolyzed to obtain rare earth oxide-doped tungsten oxide. The ambient temperature of the pyrolysis is not lower than 700℃. The rare earth oxide-doped tungsten oxide was calcined in a reducing atmosphere to obtain a rare earth oxide-doped tungsten composite material.

2. The preparation method according to claim 1, characterized in that, The tungsten salt solution includes at least one of ammonium tungstate solution and ammonium metatungstate solution.

3. The preparation method according to claim 2, characterized in that, The WO3 content in the tungsten salt solution is 100~370g / L.

4. The preparation method according to claim 1, characterized in that, The rare earth metal salt solution includes at least one of cerium salt solution, lanthanum salt solution, yttrium salt solution, and ytterbium salt solution.

5. The preparation method according to claim 4, characterized in that, The content of rare earth metal salts in the rare earth metal salt solution is not higher than 10 g / L.

6. The preparation method according to claim 1, characterized in that, The atomization conditions include: a gas-liquid ratio not exceeding 2:1, a gas pressure not exceeding 0.5 MPa, and a liquid pressure not exceeding 0.6 MPa.

7. The preparation method according to claim 1 or 6, characterized in that, The ambient temperature for atomization and pyrolysis is 700~900℃.

8. The preparation method according to claim 1, characterized in that, The reducing atmosphere is hydrogen. The calcination temperature is 800~1000℃, and the holding time is no more than 2 hours.

9. The rare earth oxide-doped tungsten composite material prepared by the preparation method according to any one of claims 1 to 8, characterized in that, It includes a submicron-sized tungsten matrix and nano-sized rare earth oxides doped at the grain boundaries of the submicron-sized tungsten matrix.

10. The application of the rare earth oxide-doped tungsten composite material according to claim 9 in the preparation of alloys.

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