Rare earth doped tungsten oxide 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 rare earth doped tungsten oxide composite material and a preparation method and application thereof. The preparation method comprises the following steps: by taking a nano rare earth oxide particle suspension as a raw material, crushing the solution and the suspension into tiny liquid drops to be dispersed and distributed in a manner of centrifugal atomization with a tungsten salt solution, forming mixed liquid drops according to a certain proportion, and then rapidly drying and forming the mixed liquid drops by heating to obtain a precursor; the rare earth element is wrapped in the precursor in the form of nano oxide particles. And then through high-temperature calcination, rare earth elements are uniformly distributed at the grain boundary of tungsten oxide in the form of nano oxide, and no pollutant is left after calcination. The suspension-solution mixing method can effectively solve the problems of non-uniform distribution of rare earth elements in the solid-solid mixing process and non-uniform particle size of rare earth oxide in the traditional ball milling process.

Description

Technical Field

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

[0002] Tungsten possesses excellent physical and chemical properties, such as a high melting point, high thermal conductivity, and high high-temperature strength. The particle size and uniformity of the original tungsten powder significantly affect the properties of tungsten alloys. Furthermore, tungsten powder is a crucial raw material for preparing cemented carbides. Adding rare earth elements to tungsten alloys and cemented carbides can improve alloy performance. Traditionally, rare earth oxide powder and tungsten powder or tungsten carbide powder are added through composite ball milling during the ball milling stage. However, conventional ball milling methods are currently ineffective in reducing the size of rare earth oxide powder. Furthermore, the small amount of rare earth oxide particles after ball milling is difficult to achieve uniform mixing with the matrix in the solid state, resulting in larger and less uniform rare earth oxide particles in the matrix after subsequent sintering. Summary of the Invention

[0003] The purpose of this invention is to provide a rare earth-doped tungsten oxide 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-doped tungsten oxide composite materials, comprising the following steps: The rare earth oxide suspension and the tungsten salt solution were centrifuged and atomized separately. The droplets formed by atomization were then combined to obtain the rare earth oxide-ammonium paratungstate precursor. The ambient temperature for the composite process was not higher than 300°C. The rare earth oxide-ammonium paratungstate precursor is calcined to obtain the rare earth doped tungsten oxide composite material.

[0005] Preferably, the rare earth oxides in the rare earth oxide suspension include at least one of cerium oxide, lanthanum oxide, yttrium oxide, and ytterbium oxide; The mass concentration of rare earth oxides in the rare earth oxide suspension does not exceed 10 g / L.

[0006] Preferably, the method for preparing the rare earth oxide suspension includes: mixing rare earth oxides and a dispersant, and then ball milling them; The dispersant includes polyethylene glycol 600 and polyethylene glycol 400, wherein the mass ratio of polyethylene glycol 600 to polyethylene glycol 400 is 1:1~5; The ball mill has a ball-to-material ratio of 1~15:1, a rotation speed of 500~1000 rpm, and a time of 3~20 h.

[0007] Preferably, the tungsten salt solution includes at least one of ammonium tungstate solution and ammonium metatungstate solution; The WO3 content in the tungsten salt solution is 100~370g / L; The volume ratio of the rare earth oxide suspension to the tungsten salt solution is 1:4.

[0008] Preferably, the rotation speed of the centrifugal atomization is 1000~30000 rpm.

[0009] Preferably, the ambient temperature of the composite is 160~300℃.

[0010] Preferably, the calcination temperature is 600~1100℃; the calcination atmosphere is air.

[0011] The present invention also provides a rare earth-doped tungsten oxide composite material prepared by the preparation method described above, comprising a micron-sized tungsten oxide matrix and a nano-sized rare earth-tungsten composite oxide doped at the grain boundaries of the micron-sized tungsten oxide matrix.

[0012] Preferably, the mass percentage of rare earth elements in the rare earth-doped tungsten oxide composite material is no more than 3%.

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

[0014] This invention provides a method for preparing a rare earth-doped tungsten oxide composite material, comprising the following steps: centrifuging and atomizing a rare earth oxide suspension and a tungsten salt solution separately; combining the atomized droplets to obtain a rare earth oxide-ammonium paratungstate precursor; the atomization temperature is not higher than 300℃; and calcining the rare earth oxide-ammonium paratungstate precursor to obtain the rare earth-doped tungsten oxide composite material. This invention uses a nano-rare earth oxide particle suspension as raw material, and centrifuges and a tungsten salt solution to break the solution and suspension into tiny droplets that are dispersed and distributed in a certain proportion, forming mixed droplets. Heating then causes the mixed droplets to rapidly crystallize to form a precursor, in which rare earth elements exist as nano-oxide particles. Subsequently, high-temperature calcination forms a rare earth-tungsten composite oxide, which is uniformly distributed at the tungsten oxide grain boundaries, and no contaminants remain after calcination. This suspension-solution mixing method effectively solves the problems of uneven distribution of rare earth elements during solid-solid mixing and uneven particle size of rare earth oxides in traditional ball milling processes. Attached Figure Description

[0015] Figure 1 The images show the physical composition and particle size distribution of the suspension obtained in Example 1. Figure 2Here is a SEM image of the precursor obtained in Example 1; Figure 3 The XRD pattern of the precursor obtained in Example 1; Figure 4 SEM image of the composite material obtained in Example 1; Figure 5 The image shows the XRD pattern of the composite material obtained in Example 1. Figure 6 TEM image of the composite material obtained in Example 1; Figure 7 The XRD pattern of the composite tungsten powder in Test Example 1; Figure 8 Fracture morphology of WC-6.5Co cemented carbide prepared from the composite material of Example 1 and untreated tungsten powder. Detailed Implementation

[0016] This invention provides a method for preparing rare earth-doped tungsten oxide composite materials, comprising the following steps: The rare earth oxide suspension and the tungsten salt solution were centrifuged and atomized separately. The droplets formed by atomization were then combined to obtain the rare earth oxide-ammonium paratungstate precursor. The ambient temperature for the composite process was not higher than 300°C. The rare earth oxide-ammonium paratungstate precursor is calcined to obtain the rare earth doped tungsten oxide composite material.

[0017] In this invention, a rare earth oxide suspension and a tungsten salt solution are centrifuged and atomized separately. The droplets formed by atomization are then combined to obtain a rare earth oxide-ammonium paratungstate precursor.

[0018] In this invention, the rare earth oxides in the rare earth oxide suspension preferably include at least one of cerium oxide, lanthanum oxide, yttrium oxide, and ytterbium oxide; the mass concentration of the rare earth oxides in the rare earth oxide suspension is preferably no more than 10 g / L. In this invention, the particle size of the rare earth oxides in the rare earth oxide suspension is in the nanometer range.

[0019] In this invention, the preferred method for preparing the rare earth oxide suspension includes: mixing rare earth oxides and a dispersant, and then ball milling; the dispersant preferably includes polyethylene glycol 600 and polyethylene glycol 400, and the mass ratio of polyethylene glycol 600 to polyethylene glycol 400 is preferably 1:1 to 5, specifically 1:1, 1:2, 1:3, 1:4, or 1:5; the ball-to-material ratio of the ball milling is preferably 1 to 15:1, specifically 1:1, 3:1, 5:1, 8:1, 10:1, 12:1, or 15:1; the rotation speed is preferably 500 to 1000 rpm, specifically 500 rpm, 600 rpm, 700 rpm, 800 rpm, 900 rpm, or 1000 rpm; and the time is preferably 3 to 20 hours, specifically 3 hours, 5 hours, 10 hours, 15 hours, or 20 hours.

[0020] In this invention, the tungsten salt solution preferably includes at least one of ammonium tungstate solution and ammonium metatungstate solution; 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. In this invention, the volume ratio of the rare earth oxide suspension to the tungsten salt solution is preferably 1:4.

[0021] In this invention, the preferred rotation speed of the centrifugal atomization is 1000~30000 rpm, specifically 1000 rpm, 5000 rpm, 10000 rpm, 15000 rpm, 20000 rpm, 25000 rpm, or 30000 rpm. In this invention, the temperature of the centrifugal atomization and the temperature of the composite process are the same, and will not be elaborated further here.

[0022] In this invention, the ambient temperature of the composite is not higher than 300°C, preferably 160~300°C, specifically 160°C, 180°C, 200°C, 250°C, or 300°C.

[0023] After obtaining the rare earth oxide-ammonium paratungstate precursor, the present invention calcines the rare earth oxide-ammonium paratungstate precursor to obtain the rare earth doped tungsten oxide composite material.

[0024] In this invention, the calcination temperature is preferably 600~1100℃, specifically 600℃, 700℃, 800℃, 900℃, 1000℃, or 1100℃; the holding time is preferably 4 hours; and the calcination atmosphere is preferably air.

[0025] The present invention also provides a rare earth-doped tungsten oxide composite material prepared by the preparation method described above, comprising a micron-sized tungsten oxide matrix and a nano-sized rare earth-tungsten composite oxide doped at the grain boundaries of the micron-sized tungsten oxide matrix.

[0026] In this invention, the mass percentage of rare earth elements in the rare earth-doped tungsten oxide composite material is preferably no more than 3%.

[0027] The present invention also provides the application of the rare earth-doped tungsten oxide composite material described in the above technical solution in the preparation of alloys.

[0028] Unless otherwise specified, the materials and equipment used in this invention are all commercially available products in the field.

[0029] 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.

[0030] Example 1 Polyethylene glycol 600 and polyethylene glycol 400 were selected as dispersants with a mass ratio of 1:4. Cerium oxide and dispersants were mixed and ball-milled with a ball-to-material ratio of 12:1, a rotation speed of 600 rpm, and a time of 3 h to obtain a 10 g / L cerium oxide particle suspension. At an ambient temperature of 180℃, a cerium oxide particle suspension with a volume ratio of 1:4 and an ammonium tungstate aqueous solution (with a WO3 content of 370 g / L) were placed in a centrifugal spray device for centrifugal atomization at a speed of 25000 rpm. The droplets formed by atomization were combined to obtain a rare earth oxide-ammonium paratungstate precursor. The rare earth oxide-ammonium paratungstate precursor obtained above was calcined in air at 800°C for 4 hours to obtain a rare earth-doped tungsten oxide composite material, wherein the mass percentage of rare earth elements was 0.82%.

[0031] Performance testing Test Example 1 Figure 1 Here are the physical images and particle size distribution diagrams of the cerium oxide particle suspension obtained in Example 1. Figure 1 It can be seen that the rare earth oxides obtained after ball milling have a size of approximately 150 nm.

[0032] Figure 2 Here is a SEM image of the precursor obtained in Example 1. Figure 3 The XRD pattern of the precursor obtained in Example 1 shows that the precursor has an amorphous structure and the spherical particle size is in the micrometer range.

[0033] Figure 4 Here is a SEM image of the composite material obtained in Example 1. Figure 5The image shows the XRD pattern of the composite material obtained in Example 1. Figure 6 The image shows a TEM image of the composite material obtained in Example 1. It can be seen that after calcination, the tungsten oxide particles are micrometer-sized, and uniformly distributed nano-sized rare earth-tungsten composite oxides are found at the tungsten oxide grain boundaries.

[0034] The composite material obtained in Example 1 was reduced at 900°C for 1 hour to obtain composite tungsten powder. Figure 7 The image shows the XRD pattern of the composite tungsten powder. Compared with tungsten powder without rare earth elements, the rare earth elements, tungsten, and oxygen elements form compounds that are retained in the tungsten powder after reduction.

[0035] Test Example 2 The composite material obtained in Example 1 was used to prepare WC-6.5Co cemented carbide; The specific process is as follows: the 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 according to GB / T385-12015; untreated tungsten powder was used as a control. Figure 8 (a) shows the fracture morphology of the WC-6.5Co cemented carbide prepared from the composite material of Example 1. Figure 8 (b) shows the fracture morphology of WC-6.5Co cemented carbide prepared from untreated tungsten powder. Figure 8 (c) is the force-displacement curve; as can be seen from the figure, no obvious crack initiation and defects were found at the fracture surface of the WC-6.5Co cemented carbide prepared from the composite material of Example 1.

[0036] The specific results are shown in Table 1; Table 1. Performance results of the alloys obtained from the composite material preparation in Example 1.

[0037] The results show that the rare earth-doped tungsten oxide composite material provided by the present invention can effectively improve the bending strength, hardness and fracture toughness of subsequent cemented carbide products.

[0038] 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 producing a rare earth-doped tungsten oxide composite material, characterized by, The method comprises the following steps: The rare earth oxide suspension and the tungsten salt solution are centrifugally atomized respectively, and the liquid drops formed by the atomization are combined to obtain a rare earth oxide-ammonium paratungstate precursor; the combining is performed at an ambient temperature not higher than 300 DEG C; The rare earth oxide-ammonium paratungstate precursor is calcined to obtain the rare earth doped tungsten oxide composite material.

2. The production method according to claim 1, characterized by, The rare earth oxide in the rare earth oxide suspension comprises at least one of cerium oxide, lanthanum oxide, yttrium oxide and ytterbium oxide; The mass concentration of the rare earth oxide in the rare earth oxide suspension is not more than 10 g / L.

3. The production method according to claim 1 or 2, characterized by, The preparation method of the rare earth oxide suspension comprises: mixing the rare earth oxide and a dispersant, and performing ball milling; The dispersant comprises polyethylene glycol 600 and polyethylene glycol 400, and the mass ratio of the polyethylene glycol 600 to the polyethylene glycol 400 is 1:1-5; The ball-to-material ratio of the ball milling is 1-15:1, the rotating speed is 500-1000 rpm, and the time is 3-20 h.

4. The production method according to claim 2, characterized by, The tungsten salt solution comprises at least one of an ammonium tungstate solution and an ammonium metatungstate solution; The content of WO3 in the tungsten salt solution is 100-370 g / L; The volume ratio of the rare earth oxide suspension to the tungsten salt solution is 1:

4.

5. The preparation method according to claim 1, characterized in that, The rotating speed of the centrifugal atomization is 1000-30000 rpm.

6. The method of claim 1, wherein, The ambient temperature of the combining is 160-300 DEG C.

7. The preparation method according to claim 1, characterized in that, The calcination temperature is 600-1100 DEG C, and the atmosphere of the calcination is air.

8. The rare earth-doped tungsten oxide composite material prepared by the method of any one of claims 1 to 7, characterized in that, The composite material comprises a micron-sized tungsten oxide matrix and a nanometer-sized rare earth-tungsten composite oxide doped at the grain boundaries of the micron-sized tungsten oxide matrix.

9. The rare earth doped tungsten oxide composite material of claim 8, wherein, The mass percentage of the rare earth element in the rare earth doped tungsten oxide composite material is not higher than 3%.

10. Use of the rare earth doped tungsten oxide composite material in claim 8 or 9 in the preparation of an alloy.

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