Metal-doped tungsten carbide and preparation method thereof

Abstract

The invention discloses a metal-doped tungsten carbide and a preparation method thereof. The preparation method of the metal-doped tungsten carbide comprises the following steps: mixing an ammonium tungstate solution with a soluble salt of a doped metal to obtain a mixed solution; evaporating the mixed solution to obtain doped ammonium paratungstate; calcining the doped ammonium paratungstate to obtain doped blue tungsten; reducing the doped blue tungsten to obtain doped tungsten powder; and carbonizing the doped tungsten powder to obtain metal-doped tungsten carbide. By adding the doped metal soluble salt to the ammonium tungstate solution, the metal ions are uniformly distributed in the solution, ensuring that the doped metal ions are uniformly mixed in the ammonium tungstate solution, which is helpful to generate a tungsten carbide material with uniform metal doping distribution, and improving the hardness and wear resistance of the metal-doped tungsten carbide.

Description

Technical Field

[0001] The invention relates to the technical field of conversion and utilization of waste cemented carbide resources, and more specifically, to metal-doped tungsten carbide and a preparation method thereof. Background Art

[0002] Tungsten carbide has high hardness and wear resistance, but pure tungsten carbide is brittle. By adding doped metal to tungsten carbide, its brittleness can be reduced and it can be made more wear-resistant. The wear-resistant enhancement effect makes the doped tungsten carbide applicable to cutting tools, wear-resistant parts and other fields. In the prior art, tungsten carbide powder and doped metal powder are directly mixed to prepare metal-doped tungsten carbide material, and then the mixed powder material is metallurgically cast. The doped metal obtained by this method is unevenly distributed in the tungsten carbide material.

[0003] Therefore, there is an urgent need to provide a metal-doped tungsten carbide and a preparation method thereof to improve the distribution uniformity of the doped metal in the tungsten carbide material. Summary of the invention

[0004] The purpose of the present invention is to overcome the above-mentioned defects of the prior art and provide a method for preparing metal-doped tungsten carbide, comprising the following steps:

[0005] (1) mixing an ammonium tungstate solution with a soluble salt of a doping metal to obtain a mixed solution;

[0006] (2) evaporating the mixed solution to obtain doped ammonium paratungstate;

[0007] (3) The doped ammonium paratungstate is calcined to obtain doped blue tungsten;

[0008] (4) The doped blue tungsten is subjected to reduction treatment to obtain doped tungsten powder;

[0009] (5) The doped tungsten powder is carbonized to obtain the metal-doped tungsten carbide.

[0010] The present invention also provides a metal-doped tungsten carbide, which is prepared by the above-mentioned preparation method of the metal-doped tungsten carbide.

[0011] Implementing the embodiments of the present invention will have the following beneficial effects:

[0012] In this embodiment, the ammonium tungstate solution is mixed with a soluble salt of a doped metal to obtain a mixed solution; the mixed solution is evaporated to obtain doped ammonium paratungstate; the doped ammonium paratungstate is calcined to obtain doped blue tungsten; the doped blue tungsten is reduced to obtain doped tungsten powder; the doped tungsten powder is carbonized to obtain metal-doped tungsten carbide. By adding the doped metal soluble salt to the ammonium tungstate solution, the metal ions are evenly distributed in the solution, ensuring that the doped metal ions are evenly mixed in the ammonium tungstate solution, which helps to generate a tungsten carbide material with a uniform metal doping distribution. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0014] in:

[0015] Figure 1 A flow chart of the preparation method of metal-doped tungsten carbide provided by the present invention. DETAILED DESCRIPTION

[0016] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0017] Reference Figure 1 The present invention discloses a method for preparing metal-doped tungsten carbide, comprising the following steps:

[0018] (1) Mixing ammonium tungstate solution with a soluble salt of a doping metal to obtain a mixed solution.

[0019] Ammonium tungstate solution is used as the main tungsten source to provide tungstate ions. The metal element to be doped is selected and prepared into a salt soluble in water or ammonium. The doped metal soluble salt includes one or more of metal soluble salts such as ammonium chromate and ammonium metavanadate. The ammonium tungstate solution and the doped metal soluble salt are mixed in a preset ratio. The mixing process requires sufficient stirring to ensure that the doped metal ions are evenly dispersed in the ammonium tungstate solution. Furthermore, the mass ratio of tungsten to doped metal in the ammonium tungstate solution and the doped metal soluble salt is 90:1 to 400:1, the mixing temperature of the ammonium tungstate solution and the doped metal soluble salt is 25°C to 30°C, and the mixing time is 1h to 3h.

[0020] In the prior art, tungsten carbide powder and doped metal powder are directly mixed during the preparation of metal-doped tungsten carbide. The mixing of the powders often results in problems such as agglomeration and separation, resulting in uneven distribution of the doped metal in the tungsten carbide.

[0021] In this embodiment, a soluble salt of a doped metal is added to the ammonium tungstate solution, and the metal ions are evenly distributed in the solution, which can ensure that the doped metal ions are evenly mixed at the molecular level in the ammonium tungstate solution, and is helpful in generating a tungsten carbide material with a uniform doping distribution of the doped metal in subsequent steps.

[0022] (2) Evaporating the mixed solution to obtain doped ammonium paratungstate.

[0023] The mixed solution is placed in an evaporator for evaporation. The ammonia is gradually evaporated by heating. The solute concentration in the solution gradually increases, and the solute begins to precipitate to form crystals, i.e., doped ammonium paratungstate. The evaporation temperature is 80°C to 100°C.

[0024] (3) Doped ammonium paratungstate is calcined to obtain doped blue tungsten.

[0025] The doped ammonium paratungstate is placed in a reduction furnace for calcination to obtain doped blue tungsten. Furthermore, the calcination temperature is 650° C. to 900° C., and the calcination time is 20 min to 40 min.

[0026] (4) The doped blue tungsten is subjected to reduction treatment to obtain doped tungsten powder.

[0027] The doped blue tungsten is reduced with hydrogen at high temperature to obtain doped tungsten powder. The reduction temperature affects the particle size and purity of the tungsten powder. Furthermore, the reduction temperature is 600°C to 950°C.

[0028] Furthermore, the doped tungsten powder obtained by reduction can be crushed and sieved to obtain doped tungsten powder of a desired particle size.

[0029] (5) The doped tungsten powder is carburized to obtain metal-doped tungsten carbide.

[0030] After the doped tungsten powder is mixed with a carbon source (such as graphite, activated carbon, etc.), a carbonization reaction is carried out at a high temperature to obtain metal-doped tungsten carbide. The reaction temperature and reaction time will affect the grain size and purity of the metal-doped tungsten carbide. Furthermore, the temperature of the carbonization treatment is 1300℃~1500℃, and the time is 10min~20min.

[0031] It can be understood that in this embodiment, the ammonium tungstate solution is mixed with the doped metal soluble salt to obtain a mixed solution; the mixed solution is evaporated to obtain doped ammonium paratungstate; the doped ammonium paratungstate is calcined to obtain doped blue tungsten; the doped blue tungsten is reduced to obtain doped tungsten powder; the doped tungsten powder is carbonized to obtain metal-doped tungsten carbide. By adding the doped metal soluble salt to the ammonium tungstate solution, the metal ions will be evenly distributed in the solution, ensuring that the doped metal ions are evenly mixed in the ammonium tungstate solution, which is helpful to generate a tungsten carbide material with uniform metal doping distribution and improve the hardness and wear resistance of the metal-doped tungsten carbide. Specific embodiment:

[0033] Embodiment 1:

[0034] (1) 1000 ml of ammonium tungstate solution (W: 200 g / L) was mixed with 3.5 g of ammonium chromate (Cr: 1.19 g) at 25°C for 3 h to obtain a mixed solution;

[0035] (2) placing the mixed solution in an evaporator and evaporating it at a temperature of 85° C. to obtain doped ammonium paratungstate;

[0036] (3) The doped ammonium paratungstate is placed in a reduction furnace for calcination at a temperature of 650° C. for 40 min to obtain doped blue tungsten;

[0037] (4) performing reduction treatment on the doped blue tungsten at a temperature of 700° C. to obtain doped tungsten powder;

[0038] (5) After the doped tungsten powder is mixed with graphite, a carbonization reaction is carried out at a temperature of 1300° C. for 20 minutes to obtain chromium-doped tungsten carbide.

[0039] Embodiment 2:

[0040] (1) 1000 ml of ammonium tungstate solution (W: 200 g / L) was mixed with 3.5 g of ammonium chromate (Cr: 1.19 g) at 30°C for 2 h to obtain a mixed solution;

[0041] (2) placing the mixed solution in an evaporator and evaporating it at a temperature of 95° C. to obtain doped ammonium paratungstate;

[0042] (3) The doped ammonium paratungstate is placed in a reduction furnace for calcination at a temperature of 800° C. for 30 min to obtain doped blue tungsten;

[0043] (4) performing reduction treatment on the doped blue tungsten at a temperature of 800° C. to obtain doped tungsten powder;

[0044] (5) After the doped tungsten powder is mixed with graphite, a carbonization reaction is carried out at a temperature of 1400° C. for 15 minutes to obtain chromium-doped tungsten carbide.

[0045] Embodiment 3:

[0046] (1) 1000 ml of ammonium tungstate solution (W: 200 g / L) was mixed with 3.5 g of ammonium chromate (Cr: 1.19 g) at 25°C for 1 h to obtain a mixed solution;

[0047] (2) placing the mixed solution in an evaporator for evaporation at a temperature of 100° C. to obtain doped ammonium paratungstate;

[0048] (3) The doped ammonium paratungstate is placed in a reduction furnace for calcination at a temperature of 900° C. for 20 min to obtain doped blue tungsten;

[0049] (4) performing reduction treatment on the doped blue tungsten at a temperature of 950° C. to obtain doped tungsten powder;

[0050] (5) After the doped tungsten powder is mixed with graphite, a carbonization reaction is carried out at a temperature of 1500° C. for 10 minutes to obtain chromium-doped tungsten carbide.

[0051] Comparative Example:

[0052] (1) 213 g of tungsten carbide powder (W: 200 g) and 1.19 g of chromium powder were mixed to obtain a mixed powder.

[0053] (2) The mixed powder is granulated.

[0054] (3) The granulated powder is placed in a mold and pressed into a green body.

[0055] (4) Sintering the green body at 1300° C. for 30 min to allow metallurgical bonding between the powder particles to form chromium-doped tungsten carbide.

[0056] Table 1: Tensile strength of tungsten carbide rods prepared in Examples 1 to 3 and Comparative Examples

[0057] tensile strength Example 1 <![CDATA[3600N / mm 2 <!-- 3 -->]]> Example 2 <![CDATA[3700N / mm 2 ]]> Example 3 <![CDATA[3680N / mm 2 ]]> Comparative Example <![CDATA[3100N / mm 2 ]]>

[0058] The chromium-doped tungsten carbide obtained in Examples 1 to 3 and the comparative example were used to prepare metal-doped tungsten carbide rods, and their tensile strengths were measured. The chromium-doped tungsten carbide materials prepared in Examples 1 to 3 had uniform chromium distribution, and the prepared tungsten carbide rods all had high tensile strength. The chromium-doped tungsten carbide materials prepared in the comparative example had uneven chromium distribution, and the tensile strength of the prepared tungsten carbide rods was significantly reduced.

[0059] The above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the patent application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A method for preparing metal-doped tungsten carbide, characterized in that: The following steps are involved: (1) mixing an ammonium tungstate solution with a soluble salt of a doping metal to obtain a mixed solution; (2) evaporating the mixed solution to obtain doped ammonium paratungstate; (3) The doped ammonium paratungstate is calcined to obtain doped blue tungsten; (4) The doped blue tungsten is subjected to reduction treatment to obtain doped tungsten powder; (5) The doped tungsten powder is subjected to a carbonization treatment to obtain the metal-doped tungsten carbide.

2. The method for preparing metal-doped tungsten carbide according to claim 1, characterized in that: The mass ratio of tungsten to doping metal in the ammonium tungstate solution and the doping metal soluble salt is 90:1 to 400:

1.

3. The method for preparing metal-doped tungsten carbide according to claim 2, characterized in that: The doped metal soluble salt includes one or more than two of ammonium chromate and ammonium metavanadate.

4. The method for preparing metal-doped tungsten carbide according to claim 1, characterized in that: In step (1), the temperature for mixing the ammonium tungstate solution and the soluble salt of the doped metal is 25° C. to 30° C., and the mixing time is 1 h to 3 h.

5. The method for preparing metal-doped tungsten carbide according to claim 1, characterized in that: The evaporation temperature in step (2) is 80°C to 100°C.

6. The method for preparing metal-doped tungsten carbide according to claim 1, characterized in that: The calcination temperature in step (3) is 650° C. to 900° C., and the calcination time is 20 min to 40 min.

7. The method for preparing metal-doped tungsten carbide according to claim 1, characterized in that: The temperature of the reduction treatment in step (4) is 600°C to 950°C.

8. The method for preparing metal-doped tungsten carbide according to claim 1, characterized in that: The temperature of the carbonization treatment in step (4) is 1300° C. to 1500° C., and the time of the carbonization treatment is 10 min to 20 min.

9. The method for preparing metal-doped tungsten carbide according to claim 8, characterized in that: The carbonization treatment includes mixing the doped tungsten powder with a carbon source and performing a carbonization reaction at a high temperature.

10. A metal-doped tungsten carbide, characterized in that: The metal-doped tungsten carbide is prepared by the preparation method of any one of claims 1 to 9.

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