METHOD FOR IN-SITU SYNTHESIS OF TUNGSTEN CARBIDE POWDER

Abstract

The present disclosure provides a method for in-situ synthesizing tungsten carbide powder. In this method, cemented carbide scrap is used as an electrode and the molten salt electrolysis process is used to in-situ synthesize tungsten carbide powder, where a bidirectional pulse is used in the molten salt electrolysis process. In the method provided by the present disclosure, by using the bidirectional pulse and using the cemented carbide scrap as electrode in the molten salt medium, when the tungsten carbide scrap is oxidized, tungsten is dissolved in ionic form, deposited after the direction of current changes, and reacted with the carbon anode sludge in situ to generate tungsten carbide powder. In the present disclosure, the carbon anode sludge is treated appropriately, the recycled product can be used in upmarket application, there is no need to apply complicated processes to process the tungsten powder into tungsten carbide, and the tungsten carbide nanopowder with high-performance can be recycled and prepared in a short process.

Claims

1. A method for in-situ synthesizing tungsten carbide powder, comprising: using at least one cemented carbide scrap as an electrode, and in-situ synthesizing tungsten carbide powder by a molten salt electrolysis process, wherein bidirectional pulse is used to electrolyse in a molten salt electrolysis process.

2. The method for in-situ synthesizing tungsten carbide powder according to claim 1, wherein a ratio of a height of a forward pulse to a height of a reverse pulse is 1:1 and a ratio of time of the forward pulse to time of the reverse pulse is 1:1.

3. The method for in-situ synthesizing tungsten carbide powder according to claim 2, wherein the height of the forward pulse is 150-250 mA and the time of the forward pulse is 30-50 s.

4. The method for in-situ synthesizing tungsten carbide powder according to claim 1, wherein in the molten salt electrolysis process, molten salt of fluoride and/or chloride is used as an electrolyte.

5. The method for in-situ synthesizing tungsten carbide powder according to claim 4, wherein the molten salt comprises a mixture of NaF and KF.

6. The method for in-situ synthesizing tungsten carbide powder according to claim 1, wherein the at least cemented carbide scrap includes two separate cemented carbide scrap as two electrodes.

7. The method for in-situ synthesizing tungsten carbide powder according to claim 1, wherein a purity of the tungsten carbide powder is more than 99%.

8. The method for in-situ synthesizing tungsten carbide powder according to claim 1, wherein the tungsten carbide powder has a particle size in a range of from about 1 nm to about 1,000 nm.

9. The method for in-situ synthesizing tungsten carbide powder according to claim 1, wherein the tungsten carbide powder has a particle size in a range of from about 80 nm to about 100 nm.

10. The method for in-situ synthesizing tungsten carbide powder according to claim 2, wherein a purity of the tungsten carbide powder is more than 99%.

11. The method for in-situ synthesizing tungsten carbide powder according to claim 3, wherein a purity of the tungsten carbide powder is more than 99%.

12. The method for in-situ synthesizing tungsten carbide powder according to claim 4, wherein a purity of the tungsten carbide powder is more than 99%.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0016] FIG. 1 is a current-time curve of the first 300 seconds (s) of the electrolysis according to Embodiment 1 of the present disclosure.

[0017] FIG. 2 is a voltage-time curve of the first 300 s of the electrolysis according to Embodiment 1 of the present disclosure.

[0018] FIG. 3 is an analysis diagram about the composition of the product obtained after electrolysis for 6 hours according to Embodiment 1 of the present disclosure.

[0019] FIG. 4 is a current time curve of the first 300 s of the electrolysis according to Embodiment 3 of the present disclosure.

[0020] FIG. 5 is a voltage time curve of the first 300 s of the electrolysis according to Embodiment 3 of the present disclosure.

[0021] FIG. 6 is an analysis diagram about the composition of the product obtained after electrolysis for 6 hours according to Embodiment 3 of the present disclosure.

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0022] In order to explain the objectives, solutions, and advantages of the embodiments of the present disclosure more clearly, the solutions according to the embodiments of the present disclosure will be clearly and completely described below. It should be noted that, the described embodiments are part of embodiments of the present disclosure, rather than all of the embodiments. Based on embodiments in the present disclosure, all other embodiments obtained by those of ordinary skill in the art without creative work are within the scope of protection of the present disclosure.

[0023] The experimental reagents and materials used in embodiments of the present disclosure are commercially available, unless otherwise specified. The cemented carbide scraps contain tungsten and carbide. The carbide in the cemented carbide scraps acts as the source for carbon in the tungsten carbide powder as the product provided in the present disclosure. As shown in Emodiments 1 and 3 below, the two separate cemented carbide scraps are preferably used as both electrodes including both anode and cathode for desired reaction efficiency. As shown in Embodiment 2, a cemented carbide scrap can be used as one electride while a counter electrode such as a graphite rod is used. The term “anode sludge” is used herein to indicate the place whether anodic oxidation reaction occurs. The tungsten carbide produced is in the form of powder. Such a tungsten carbide (WC) powder falls into the electode mud immediately after produced, so it will not participate in any further reaction.

Embodiment 1

[0024] The present embodiment provides a method for in-situ synthesizing tungsten carbide powder. The method includes the following steps: using NaF—KF molten salt having a temperature of 800° C. as electrolyte; under a protection of inert gas, applying a pulse current with a pulse height of 150 mA between two electrodes, which are two cemented carbide scraps, where the time of forward pulse is 30 s and the time of reverse pulse is 30 s; and collecting tungsten carbide powder in the molten salt after a total of 6 hours of electrolysis. The NaF—KF molten salt had a molar ratio of 2:3 for NaF to KF. FIG. 1 shows a current time curve of the first 300 s and FIG. 2 shows the voltage time curve of the first 300 s.

[0025] An analysis diagram about the composition of a product obtained after 6 hours of electrolysis is shown by FIG. 3, and it can be seen that the product is pure tungsten carbide, which can be used as an upmarket product.

Embodiment 2

[0026] The present embodiment provides a method for in-situ synthesizing tungsten carbide powder. The method includes the following steps: using NaF—KF molten salt (having a molar ratio of 2:3) as electrolyte; under a protection of inert gas, applying a pulse current with a pulse height of 200 mA between a working electrode which is a cemented carbide scrap and a counter electrode which is a graphite rod, where the time of forward pulse is 40 s and the time of reverse pulse is 40 s; and collecting tungsten carbide powder in the molten salt after a total of 5 hours of electrolysis.

Embodiment 3

[0027] The present embodiment provides a method for in-situ synthesizing tungsten carbide powder. The method includes the following steps: using NaF—KF molten salt (having a molar ratio of 2:3) having a temperature of 800° C. as electrolyte; under a protection of inert gas, applying a pulse current with the pulse height of 100 mA between two electrodes which are two cemented carbide scraps, where the time of the forward pulse is 20 s and the time of the reverse pulse is 20 s, and collecting tungsten carbide powder in the molten salt after a total of 6 hours of electrolysis. FIG. 4 shows a current time curve of the first 300 s and FIG. 5 shows a voltage time curve of the first 300 s.

[0028] An analysis diagram about the composition of a product obtained after 6 hours of electrolysis is shown by FIG. 6, and it can be seen that the phases containing tungsten include tungsten carbide and a small amount of impurities of tungsten phase, which is a result of insufficient reaction caused by insufficient pulse height and short retention time.

[0029] It should be noted that the above embodiments are only used to explain the solutions of the present disclosure, but are not limited thereto; although the present disclosure has been described in detail with reference to the foregoing embodiments, it should be understood by those skilled in the art that they can still modify the solutions documented in the foregoing embodiments and make equivalent substitutions to a part of the features; and these modifications and substitutions do not make the essence of the corresponding solutions depart from the scope of the solutions of various embodiments of the present disclosure.

Industrial Applicability

[0030] The present disclosure provides a method for in-situ synthesizing tungsten carbide powder. In the method provided by the present disclosure, cemented carbide scrap is used as an electrode and the molten salt electrolysis process is used to in-situ synthesize tungsten carbide powder, where a bidirectional pulse is used in the molten salt electrolysis process. In the method provided by the present disclosure, by using the bidirectional pulse and using the cemented carbide scrap as electrode in the molten salt medium, when the tungsten carbide scrap is oxidized, tungsten is dissolved in ionic form, deposited after the direction of current changes, and reacted with the carbon anode sludge in situ to generate tungsten carbide powder. In the present disclosure, the carbon anode sludge is treated appropriately, the recycled product can be used in upmarket application, there is no need to apply complicated processes to process the tungsten powder into tungsten carbide, the tungsten carbide nanopowder with high-performance can be recycled and prepared in a short process, and there is a good commercial value and application prospect.