A plate-like ultra-coarse tungsten carbide single crystal and a method for preparing the same

Abstract

The application provides a plate-shaped super-coarse tungsten carbide monocrystal and a preparation method thereof. The preparation method comprises the following steps: mixing tungsten carbide, a flux metal, graphite and an inducing agent, heating to melting, keeping warm for reaction, cooling to room temperature after the reaction is completed, and separating to obtain the plate-shaped super-coarse tungsten carbide monocrystal. The flux metal is metal iron or cobalt. The inducing agent is a mixture of metal yttrium, titanium and vanadium. The method has the advantages of easy raw material source, simple synthesis method, low cost, and the obtained tungsten carbide monocrystal is complete in development, and can be used in hard alloys in the geological and mining industries.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of tungsten metallurgy, and more particularly to a plate-shaped ultra-coarse tungsten carbide and a preparation method thereof. BACKGROUND

[0002] Coarse tungsten carbide has the advantages of few micro-defects, high microhardness, good impact toughness, and complete grain development, and is a high-quality raw material for preparing earth-mining hard alloys. Coarse tungsten carbide hard alloys can achieve high impact toughness and excellent fatigue resistance of mining tools. Generally, the hardness (i.e. wear resistance) and strength (i.e. fracture resistance) of hard alloys can be regulated by changing the morphology and particle size of tungsten carbide in the hard alloy, the type and content of the binder phase, and the addition amount of other tungsten carbides, so that the hard alloys are widely used in various places.

[0003] Tungsten carbide (WC) is a close-packed hexagonal crystal with anisotropy, and the traditional micro-morphology is a triangular prism structure. The mechanical properties of different crystal planes are quite different, and the hardness and strength on the WC (0001) crystal plane are much higher than those on other crystal planes (about twice). However, the hardness and strength of hard alloys are a pair of contradictory parameters, and the improvement of one performance usually comes at the expense of the other. If the preferred growth of the WC (0001) crystal plane or the growth rate of WC on the (1010) crystal plane can be inhibited, the elongation ratio (defined as the ratio of the lengths of the triangular prism parallel and perpendicular to the (0001) crystal plane) of the WC triangular prism crystal can be expanded, i.e. the plate-shaped transformation of the WC grain can be realized. By increasing the proportion of the WC (0001) plane, the hardness and strength of the WC grain can be improved at the same time, thereby greatly improving the mechanical properties of the hard alloy. Therefore, the plate-shaped regulation of the traditional WC triangular prism morphology can better solve the above-mentioned contradiction.

[0004] At present, the preparation method of tungsten carbide powder is mainly to mix tungsten powder and carbon powder and then carbonize at high temperature. However, since the reaction is a solid-solid reaction and there is a large density difference between tungsten and tungsten carbide, the carbonization process is often accompanied by the problem of grain explosion, and it is difficult to obtain single-crystal WC particles with good grain development. Secondly, the diffusion speed of carbon in tungsten grain is slow, and the existence of large-particle tungsten powder will lead to incomplete carbonization, thereby seriously affecting the mechanical properties of the WC grain. In addition, if you want to obtain plate-shaped WC grains, you usually need special sintering process, strict control of the morphology of raw materials or addition of inducers. Although these means can make a certain amount of WC grains develop towards plate-shaped, they will also cause uncontrollable changes in the morphology of more WC grains, and at the same time, affect the structure of the alloy, greatly reducing the stability of its performance. Therefore, the known methods cannot obtain ideal ultra-coarse single-crystal tungsten carbide particles with plate-shaped morphology. SUMMARY

[0005] In order to solve the above technical problems in the prior art, the present application provides a preparation method of plate-shaped super-coarse tungsten carbide single crystal, which comprises the following steps: heating tungsten carbide, graphite, flux metal and an inducing agent to form a melt, and then performing a reaction after heat preservation, and finally cooling and separating to obtain plate-shaped super-coarse tungsten carbide single crystal. The method can effectively control the morphology of tungsten carbide and promote the plate-shaped growth of tungsten carbide.

[0006] In order to achieve the above-mentioned purpose, the technical scheme of the present application is as follows:

[0007] A preparation method of plate-shaped super-coarse tungsten carbide single crystal, comprising the following steps:

[0008] Mixing tungsten carbide, flux metal, graphite and an inducing agent, heating to melt, then performing a reaction after heat preservation, cooling to room temperature after the reaction is completed, and separating to obtain plate-shaped super-coarse tungsten carbide single crystal;

[0009] The flux metal is metal iron or cobalt, and the inducing agent is a mixture of metal yttrium, titanium and vanadium.

[0010] In some embodiments, the mass of the inducing agent is 0.5-3% of the total mass of the tungsten carbide, flux metal and graphite.

[0011] In some embodiments, the inducing agent consists of the following components in percentage by mass:

[0012] Titanium 50-90%

[0013] Yttrium 0-25%

[0014] Vanadium 0-25%;

[0015] The content of yttrium and vanadium is >0.

[0016] In some embodiments, the mass ratio of the tungsten carbide, flux metal and graphite is (40-60):(60-40):(5-10). Preferably, the mass ratio of the tungsten carbide, flux metal and graphite is (45-55):(55-45):(5-10).

[0017] In some embodiments, the reaction temperature is 1550-1700℃.

[0018] In some embodiments, the reaction time is 1-3h.

[0019] In some embodiments, the heating reaction is carried out under vacuum condition, and the vacuum degree is ≤50Pa; or the heating reaction is carried out under inert gas protection, or the heating reaction is carried out under reducing atmosphere.

[0020] In some embodiments, the reducing atmosphere is specifically a mixed gas atmosphere consisting of 90 vol.% N2 and 10 vol.% H2, or a CO gas atmosphere.

[0021] In some embodiments, the cooling rate is 0.5-30℃ / min.

[0022] In some embodiments, after cooling to room temperature, the plate-like coarse-grained tungsten carbide is separated by anodic stripping voltammetry, and then washed with water and dried.

[0023] In some embodiments, the acid used in the anodic stripping voltammetry is dilute hydrochloric acid or dilute sulfuric acid, and the voltage is constant at 0.3-1.3V.

[0024] In some embodiments, before adding the treatment, the tungsten carbide, the flux metal and the inducer are mixed thoroughly to obtain a mixture, and the graphite is covered on the mixture.

[0025] In some embodiments, the tungsten carbide, the flux metal, the graphite and the inducer are placed in an alumina crucible for reaction.

[0026] In some embodiments, the heating device is a high-temperature muffle furnace or an induction melting furnace.

[0027] In some embodiments, the concentration of the dilute hydrochloric acid or dilute sulfuric acid is 0.8-1.2 mol / L; the dilute hydrochloric acid can be prepared by mixing concentrated hydrochloric acid with a concentration of 36.0-38.0% with deionized water in a certain proportion; and the dilute sulfuric acid can be prepared by mixing a sulfuric acid aqueous solution with a mass fraction of ≥70% with deionized water in a certain proportion. The anodic stripping voltammetry is specifically: using dilute hydrochloric acid or dilute sulfuric acid as an electrolyte, using the method of electrochemical dissolution to separate the flux metal from the tungsten carbide, the anode residue being a mixture of graphite and plate-like ultra-coarse single-crystal tungsten carbide, and the cathode deposit being the flux metal (iron or cobalt); the free carbon can be removed by washing the anode with water for multiple times to obtain the plate-like ultra-coarse single-crystal tungsten carbide.

[0028] In some embodiments, the preparation of the plate-like ultra-coarse single-crystal tungsten carbide comprises the following steps:

[0029] S1, mixing the tungsten carbide, the flux metal and the inducer uniformly and then placing them in a corundum crucible;

[0030] S2, adding graphite on the mixture obtained in step S1, compacting, heating to 1550-1700℃, reacting for 1-3h, and then controlling the cooling rate to be 0.5-30℃ / min to cool to room temperature to obtain an alloy block;

[0031] S3, separating the flux metal in the alloy block obtained in step S2 by anodic stripping voltammetry, the constant voltage is 0.3-1.3V, and the electrolyte is a dilute hydrochloric acid or dilute sulfuric acid solution with a concentration of 1mol / L;

[0032] S4, collecting the residue of the anode, removing free carbon by water washing, and obtaining the plate-shaped ultra-coarse single-crystal tungsten carbide after drying; the flux metal deposited on the cathode can be collected and recycled.

[0033] The application also provides the plate-shaped ultra-coarse single-crystal tungsten carbide prepared by the preparation method of any one of the above embodiments.

[0034] Compared with the prior art, the application has the following beneficial effects:

[0035] The application uses tungsten carbide, flux metal, graphite and specific inducers as raw materials, melts the flux metal at high temperature, and makes the tungsten carbide complete the process of "dissolution-recrystallization" in the melt, the addition of the inducers controls the morphology of the tungsten carbide and promotes the growth of the plate-shaped tungsten carbide. The ultra-coarse single-crystal tungsten carbide prepared by the method of the application is complete in development, has a significant plate-shaped morphology, has a large length-height ratio (length-height ratio≥4.5), and is a high-quality raw material for producing hard alloy products.

[0036] Further, the application further promotes the growth of the plate-shaped single-crystal tungsten carbide by controlling the ratio of the raw materials, and the addition of excessive graphite avoids the generation of M6C substances.

[0037] In addition, the alloy block obtained after cooling removes the flux metal by anodic stripping voltammetry, and removes free carbon by water washing, which can effectively remove impurities on the surface of the tungsten carbide, and the flux metal can be collected and recycled directly.

[0038] The method of the application also has the following advantages:

[0039] (1) The method of the application can control the morphology of the tungsten carbide to directly prepare the ultra-coarse single-crystal tungsten carbide with a plate-shaped morphology, and is easier in process and flow.

[0040] (2) The ultra-coarse single-crystal tungsten carbide obtained by the application has less impurities, and the obtained tungsten carbide has a high length-height ratio and is complete in development, which can greatly improve the mechanical properties of the alloy when applied to the hard alloy.

[0041] (3) The method of the application is simple in preparation process and low in cost. BRIEF DESCRIPTION OF DRAWINGS

[0042] Figure 1 The X-ray diffraction pattern of the plate-shaped ultra-coarse single-crystal tungsten carbide obtained in Example 1;

[0043] Figure 2A scanning electron microscope image of the plate-like ultra-coarse tungsten carbide monocrystal obtained in Example 1, magnification 20 times;

[0044] Figure 3 An X-ray diffraction pattern of the ultra-coarse tungsten carbide monocrystal obtained in Comparative Example 1;

[0045] Figure 4 A scanning electron microscope image of the ultra-coarse tungsten carbide monocrystal obtained in Comparative Example 1, magnification 20 times. DETAILED DESCRIPTION

[0046] In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present application. However, it will be apparent to one skilled in the art that the present application can be practiced without the specific details set forth in this description. In other instances, well-known methods have not been described in detail in order to avoid obscuring the present application.

[0047] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in the description herein is for describing particular embodiments only and is not intended to be limiting of the application.

[0048] Example 1

[0049] A plate-like ultra-coarse tungsten carbide monocrystal, the preparation method comprising the following steps:

[0050] The tungsten carbide powder, the metal cobalt powder, the inducer metal powder and the graphite powder are weighed according to the mass ratio of 46.5:46.5:1:6, wherein the inducer metal powder is composed of the metal yttrium powder, the titanium powder and the vanadium powder according to the mass percentage of 20%, 60% and 20% respectively; the tungsten carbide powder, the metal cobalt powder and the metal yttrium powder, the titanium powder and the vanadium powder are mixed uniformly by using a mortar, then the mixed powder is placed in a corundum crucible, the corresponding graphite powder is covered on the surface of the mixed powder, the mixed powder is manually compacted, and then the mixed powder is heated to 1600°C in a high-temperature muffle furnace under the protection of inert gas (nitrogen), and the mixed powder is kept for 3 hours; after the reaction is completed, the cooling speed is controlled to be 1.5°C / min, the alloy block is taken out after the temperature is reduced to room temperature; the cobalt metal in the alloy block is dissolved by using an electrochemical anodic dissolution voltammetry, the anode is the alloy block, the cathode is a copper sheet, the electrolyte is 1 mol / L dilute hydrochloric acid, and the constant voltage is 1V, so that the cobalt metal is deposited on the cathode, and the anode mud is washed with water to remove free carbon, and then dried to obtain the plate-like ultra-coarse tungsten carbide monocrystal. It is detected that the average length-height ratio of the tungsten carbide monocrystal obtained in this embodiment is 9.5, as shown in Figs. 1 and 2. Figure 1 and Figure 2 The average length-height ratio of the tungsten carbide monocrystal obtained in this embodiment is 9.5, as shown in Figs. 1 and 2.

[0051] Example 2

[0052] A plate-shaped super-coarse tungsten carbide monocrystal, and a preparation method thereof, the method comprising the following steps:

[0053] The tungsten carbide powder, the metal cobalt powder, the inducer metal powder and the graphite powder are weighed according to the mass ratio of 46.5:46.5:1:6, wherein the inducer metal powder is composed of the metal yttrium powder, the titanium powder and the vanadium powder according to the mass percentage of 20%, 60% and 20% respectively; the tungsten carbide powder, the metal cobalt powder and the metal yttrium powder, the titanium powder and the vanadium powder are mixed uniformly by using a mortar, and then the mixed powder is placed in a corundum crucible, and then the graphite powder is covered on the surface of the mixed powder, and then the mixed powder is manually compacted and heated to 1600 DEG C in a high-temperature muffle furnace under the protection of inert gas, and then the alloy block is taken out after being kept for 3 hours and the cooling speed is controlled to be 2 DEG C / min, and then the cobalt metal in the alloy block is dissolved by using an electrochemical anodic dissolution voltammetry, the anode is the alloy block, the cathode is a copper sheet, the electrolyte is 1 mol / L dilute hydrochloric acid, the constant voltage is 1 V, the iron is deposited at the cathode, and then the anode mud is washed by water to remove the free carbon, and then the anode mud is dried to obtain the plate-shaped super-coarse tungsten carbide monocrystal. The average length-height ratio of the tungsten carbide monocrystal obtained in the embodiment is 5.4.

[0054] Embodiment 3

[0055] A plate-shaped super-coarse tungsten carbide monocrystal, and a preparation method thereof, the method comprising the following steps:

[0056] The tungsten carbide powder, the metal cobalt powder, the inducer metal powder and the graphite powder are weighed according to the mass ratio of 46.5:46.5:1:6, wherein the inducer metal powder is composed of the metal yttrium powder, the titanium powder and the vanadium powder according to the mass percentage of 20%, 60% and 20% respectively; the tungsten carbide powder, the metal cobalt powder and the metal yttrium powder, the titanium powder and the vanadium powder are mixed uniformly by using a mortar, and then the mixed powder is placed in a corundum crucible, and then the graphite powder is covered on the surface of the mixed powder, and then the mixed powder is manually compacted and heated to 1600 DEG C in a high-temperature muffle furnace under the protection of inert gas, and then the alloy block is taken out after being kept for 3 hours and the cooling speed is controlled to be 2 DEG C / min, and then the cobalt metal in the alloy block is dissolved by using an electrochemical anodic dissolution voltammetry, the anode is the alloy block, the cathode is a copper sheet, the electrolyte is 1 mol / L dilute hydrochloric acid, the constant voltage is 1 V, the iron is deposited at the cathode, and then the anode mud is washed by water to remove the free carbon, and then the anode mud is dried to obtain the plate-shaped super-coarse tungsten carbide monocrystal. The average length-height ratio of the tungsten carbide monocrystal obtained in the embodiment is 5.4.

[0057] Embodiment 4

[0058] A plate-shaped super-coarse tungsten carbide monocrystal, and a preparation method thereof, the method comprising the following steps:

[0059] The tungsten carbide powder, the metal cobalt powder, the inducer metal powder and the graphite powder are weighed according to the mass ratio of 43:50:1:6, wherein the inducer metal powder is composed of the metal yttrium powder, the titanium powder and the vanadium powder according to the mass percentage of 20%, 60% and 20% respectively; the tungsten carbide powder, the metal cobalt powder and the metal yttrium powder, the titanium powder and the vanadium powder are mixed uniformly by using a mortar, then the mixed powder is placed in a corundum crucible, the graphite powder is covered on the surface of the mixed powder, the mixed powder is manually compacted, and then the mixed powder is heated to 1600 DEG C in a high-temperature muffle furnace under the protection of inert gas, the temperature is kept for 3 hours, the cooling speed is controlled to be 1.5 DEG C / min, the alloy block is taken out after the temperature decreases to room temperature; the cobalt metal in the alloy block is dissolved by using the electrochemical anodic stripping voltammetry, the anode is the alloy block, the cathode is a copper sheet, the electrolyte is 1 mol / L dilute hydrochloric acid, the constant voltage is 1 V, the cobalt is deposited on the cathode, the free carbon is removed by washing the anode mud, and then the anode mud is dried to obtain the plate-shaped super-coarse tungsten carbide monocrystal particles; the average length-height ratio of the tungsten carbide monocrystal obtained in the embodiment is 6.3.

[0060] Example 5

[0061] A plate-shaped super-coarse tungsten carbide monocrystal, a preparation method thereof comprises the following steps:

[0062] The tungsten carbide powder, the metal cobalt powder, the inducer metal powder and the graphite powder are weighed according to the mass ratio of 43:50:1:6, wherein the inducer metal powder is composed of the metal yttrium powder, the titanium powder and the vanadium powder according to the mass percentage of 20%, 60% and 20% respectively; the tungsten carbide powder, the metal cobalt powder and the metal yttrium powder, the titanium powder and the vanadium powder are mixed uniformly by using a mortar, then the mixed powder is placed in a corundum crucible, the graphite powder is covered on the surface of the mixed powder, the mixed powder is manually compacted, and then the mixed powder is heated to 1600 DEG C in a high-temperature muffle furnace under the protection of inert gas, the temperature is kept for 3 hours, the cooling speed is controlled to be 1.5 DEG C / min, the alloy block is taken out after the temperature decreases to room temperature; the cobalt metal in the alloy block is dissolved by using the electrochemical anodic stripping voltammetry, the anode is the alloy block, the cathode is a copper sheet, the electrolyte is 1 mol / L dilute hydrochloric acid, the constant voltage is 1 V, the cobalt is deposited on the cathode, the free carbon is removed by washing the anode mud, and then the anode mud is dried to obtain the plate-shaped super-coarse tungsten carbide monocrystal particles; the average length-height ratio of the tungsten carbide monocrystal obtained in the embodiment is 6.3.

[0063] Example 6

[0064] A plate-shaped super-coarse tungsten carbide monocrystal, a preparation method thereof comprises the following steps:

[0065] The tungsten carbide powder, the metal cobalt powder, the inducer metal powder and the graphite powder are weighed according to the mass ratio of 46.5:46.5:1:6, wherein the inducer metal powder is composed of the metal yttrium powder, the titanium powder and the vanadium powder according to the mass percentage of 10%, 70% and 20% respectively; the tungsten carbide powder, the metal cobalt powder and the metal yttrium powder, the titanium powder and the vanadium powder are mixed uniformly by using a mortar, then the mixed powder is placed in a corundum crucible, the corresponding graphite powder is covered on the surface of the mixed powder, and the mixed powder is manually compacted and heated to 1600 DEG C in a high-temperature muffle furnace under the protection of inert gas (nitrogen) for 3 hours; after the reaction is completed, the cooling speed is controlled to be 1.5 DEG C / min, the alloy block is taken out after the temperature decreases to room temperature; the cobalt metal in the alloy block is dissolved by using the electrochemical anodic stripping voltammetry, the anode is the alloy block, the cathode is a copper sheet, the electrolyte is 1 mol / L dilute hydrochloric acid, the constant voltage is 1 V, the cobalt metal is deposited at the cathode, the anode mud is washed by water to remove free carbon, and then is dried to obtain the plate-shaped super coarse single crystal tungsten carbide. It is detected that the average length-height ratio of the tungsten carbide single crystal obtained in the embodiment is 7.2.

[0066] Example 7

[0067] A plate-shaped super coarse single crystal tungsten carbide, a preparation method thereof comprises the following steps:

[0068] The tungsten carbide powder, the metal cobalt powder, the inducer metal powder and the graphite powder are weighed according to the mass ratio of 46.5:46.5:1:6, wherein the inducer metal powder is composed of the metal yttrium powder, the titanium powder and the vanadium powder according to the mass percentage of 20%, 56% and 24% respectively; the tungsten carbide powder, the metal cobalt powder and the metal yttrium powder, the titanium powder and the vanadium powder are mixed uniformly by using a mortar, then the mixed powder is placed in a corundum crucible, the corresponding graphite powder is covered on the surface of the mixed powder, and the mixed powder is manually compacted and heated to 1600 DEG C in a high-temperature muffle furnace under the protection of inert gas (nitrogen) for 3 hours; after the reaction is completed, the cooling speed is controlled to be 1.5 DEG C / min, the alloy block is taken out after the temperature decreases to room temperature; the cobalt metal in the alloy block is dissolved by using the electrochemical anodic stripping voltammetry, the anode is the alloy block, the cathode is a copper sheet, the electrolyte is 1 mol / L dilute hydrochloric acid, the constant voltage is 1 V, the cobalt metal is deposited at the cathode, the anode mud is washed by water to remove free carbon, and then is dried to obtain the plate-shaped super coarse single crystal tungsten carbide. It is detected that the average length-height ratio of the tungsten carbide single crystal obtained in the embodiment is 6.7.

[0069] Example 8

[0070] A plate-shaped super coarse single crystal tungsten carbide, a preparation method thereof comprises the following steps:

[0071] The tungsten carbide powder, the metal cobalt powder, the inducer metal powder and the graphite powder are weighed according to the mass ratio of 46.5:46.5:1:6, wherein the inducer metal powder is composed of the metal yttrium powder, the titanium powder and the vanadium powder according to the mass percentage of 10%, 80% and 10% respectively; the tungsten carbide powder, the metal cobalt powder, the metal yttrium powder, the titanium powder and the vanadium powder are mixed uniformly by using a mortar; the mixed powder is placed in a corundum crucible; the corresponding graphite powder is covered on the surface of the mixed powder; the mixed powder is manually compacted; the compacted mixed powder is heated to 1600 DEG C in a high-temperature muffle furnace under the protection of inert gas (nitrogen); the temperature is kept for 3 hours; after the reaction is completed, the temperature is decreased at a speed of 1.5 DEG C / min; the alloy block is taken out when the temperature decreases to room temperature; the cobalt metal in the alloy block is dissolved by using the electrochemical anodic stripping voltammetry; the anode is the alloy block; the cathode is a copper sheet; the electrolyte is 1 mol / L dilute hydrochloric acid; the constant voltage is 1V; the cobalt metal is deposited at the cathode; the anode mud is washed by water to remove free carbon; the anode mud is dried to obtain the plate-shaped super coarse single crystal tungsten carbide. It is detected that the average length-height ratio of the tungsten carbide single crystal obtained in the embodiment is 6.1.

[0072] Comparative Example 1

[0073] A plate-shaped super coarse single crystal tungsten carbide, a preparation method thereof comprises the following steps:

[0074] The tungsten carbide powder, the metal cobalt powder and the graphite powder are weighed according to the mass ratio of 47:47:6; the tungsten carbide powder and the metal cobalt powder are mixed uniformly by using a mortar; the mixed powder is placed in a corundum crucible; the corresponding graphite powder is covered on the surface of the mixed powder; the mixed powder is manually compacted; the compacted mixed powder is heated to 1600 DEG C in a high-temperature muffle furnace under the protection of inert gas (nitrogen); the temperature is kept for 3 hours; the temperature is decreased at a speed of 1.5 DEG C / min; the alloy block is taken out when the temperature decreases to room temperature; the cobalt metal in the alloy block is dissolved by using the electrochemical anodic stripping voltammetry; the anode is the alloy block; the cathode is a copper sheet; the electrolyte is 1 mol / L dilute hydrochloric acid; the constant voltage is 1V; the cobalt is deposited at the cathode; the anode mud is washed by water to remove free carbon; the anode mud is dried to obtain the super coarse single crystal tungsten carbide particles. It is detected that, as shown in Figs. 1 and 2, the average length-height ratio of the tungsten carbide single crystal obtained in the embodiment is 1.9. Figure 3 and Figure 4

[0075] Comparative Example 2

[0076] A plate-shaped super coarse single crystal tungsten carbide, a preparation method thereof comprises the following steps:

[0077] ​The tungsten carbide powder, the metal cobalt powder, the inducer metal powder and the graphite powder are weighed according to the mass ratio of 46.5:46.5:1:6, wherein the inducer metal powder is the metal titanium powder; the tungsten carbide powder, the metal cobalt powder and the titanium powder are mixed uniformly by using a mortar, then the mixed powder is placed in a corundum crucible, then the corresponding graphite powder is covered on the surface of the mixed powder, and the mixed powder is manually compacted and heated to 1600 DEG C in a high-temperature muffle furnace under the protection of inert gas (nitrogen) for 3 hours; after the reaction is completed, the cooling speed is controlled to be 1.5 DEG C / min, the alloy block is taken out after the temperature decreases to room temperature; the cobalt metal in the alloy block is dissolved by using an electrochemical anodic stripping voltammetry, the anode is the alloy block, the cathode is a copper sheet, the electrolyte is 1 mol / L dilute hydrochloric acid, the constant voltage is 1V, the cobalt metal is deposited at the cathode, the anode mud is washed by water to remove free carbon, and then is dried to obtain the plate-shaped super coarse single crystal tungsten carbide. It is detected that the average length-height ratio of the tungsten carbide single crystal obtained in the embodiment is 4.2.

[0078] Comparative Example 3

[0079] A plate-shaped super coarse single crystal tungsten carbide, and a preparation method thereof, are provided.

[0080] The tungsten carbide powder, the metal cobalt powder, the inducer metal powder and the graphite powder are weighed according to the mass ratio of 46.5:46.5:1:6, wherein the inducer metal powder is the metal titanium powder; the tungsten carbide powder, the metal cobalt powder and the titanium powder are mixed uniformly by using a mortar, then the mixed powder is placed in a corundum crucible, then the corresponding graphite powder is covered on the surface of the mixed powder, and the mixed powder is manually compacted and heated to 1600 DEG C in a high-temperature muffle furnace under the protection of inert gas (nitrogen) for 3 hours; after the reaction is completed, the cooling speed is controlled to be 1.5 DEG C / min, the alloy block is taken out after the temperature decreases to room temperature; the cobalt metal in the alloy block is dissolved by using an electrochemical anodic stripping voltammetry, the anode is the alloy block, the cathode is a copper sheet, the electrolyte is 1 mol / L dilute hydrochloric acid, the constant voltage is 1V, the cobalt metal is deposited at the cathode, the anode mud is washed by water to remove free carbon, and then is dried to obtain the plate-shaped super coarse single crystal tungsten carbide. It is detected that the average length-height ratio of the tungsten carbide single crystal obtained in the embodiment is 4.2.

[0081] Comparative Example 4

[0082] A plate-shaped super coarse single crystal tungsten carbide, and a preparation method thereof, are provided.

[0083] The tungsten carbide powder, the metal cobalt powder, the inducer metal powder and the graphite powder are weighed according to the mass ratio of 46.5:46.5:1:6, wherein the inducer metal powder is composed of the metal titanium powder and the vanadium powder according to the mass percentage of 80% and 20% respectively; the tungsten carbide powder, the metal cobalt powder, the titanium powder and the yttrium powder are mixed uniformly by using a mortar; then the mixed powder is placed in a corundum crucible, the corresponding graphite powder is covered on the surface of the mixed powder, and the mixed powder is manually compacted; then the mixed powder is heated to 1600 DEG C in a high-temperature muffle furnace under the protection of inert gas (nitrogen), and is kept for 3 hours; after the reaction is completed, the cooling speed is controlled to be 1.5 DEG C / min, the alloy block is taken out after the temperature is reduced to room temperature; the cobalt metal in the alloy block is dissolved by using an electrochemical anodic dissolution voltammetry method, the anode is the alloy block, the cathode is a copper sheet, the electrolyte is 1 mol / L dilute hydrochloric acid, the constant voltage is 1V, the cobalt metal is deposited at the cathode, the anode mud is washed by water to remove free carbon, and then is dried to obtain a plate-shaped ultra-coarse tungsten carbide single crystal. It is detected that the average length-height ratio of the tungsten carbide single crystal obtained in the embodiment is 3.7.

[0084] The technical features of the above embodiments can be combined arbitrarily, and for the sake of brevity, all possible combinations of the technical features in the above embodiments are not described, however, as long as the combinations of the technical features do not exist contradictory, it should be considered that the combinations are within the scope of the present disclosure.

[0085] The above embodiments only express several embodiments of the present application, the description is more specific and detailed, but it should not be understood as a limitation on the scope of the patent. It should be pointed out that for ordinary skilled in the art, without departing from the concept of the present application, a number of variations and improvements can be made, which are within the scope of the present application. Therefore, the scope of protection of the present application should be subject to the appended claims.

Claims

1. A method for producing a plate-like ultra-coarse single-crystal tungsten carbide, characterized by, The method comprises the following steps: The tungsten carbide, flux metal, graphite and inducer are mixed, heated to 1550-1700℃, melted, and then reacted after holding, and after the reaction is completed, the product is cooled to room temperature, separated, and a plate-shaped super-coarse tungsten carbide single crystal is obtained; The flux metal is iron or cobalt, and the inducer is a mixture of yttrium, titanium and vanadium; The mass ratio of the tungsten carbide, flux metal and graphite is (40-60):(40-60):(5-10); The added mass of the inducer is 0.5-3% of the total mass of the tungsten carbide, flux metal and graphite; The inducer consists of the following components in percentage by mass: Titanium 50-80% Yttrium 10-25% Vanadium 10-25%.

2. The method of producing a plate-like ultra coarse single-crystal tungsten carbide according to claim 1, characterized by, The mass ratio of the tungsten carbide, flux metal and graphite is (45-55):(45-55):(5-10).

3. The method of claim 1, wherein the plate-like tungsten carbide single crystal is prepared by the steps of: preparing a tungsten carbide single crystal by a chemical vapor deposition method; and performing a heat treatment on the tungsten carbide single crystal to form a plate-like tungsten carbide single crystal. The reaction time is 1-3 hours.

4. The method of claim 1, wherein the plate-like ultra coarse single-crystal tungsten carbide is prepared by the steps of: The heating reaction is performed under vacuum condition, the vacuum degree is ≤50 Pa, or the heating reaction is performed under inert gas protection, or the heating reaction is performed under reducing atmosphere, and / or the cooling rate is 0.5-30℃ / min. ​ 5. The method of producing a plate-like ultra coarse single-crystal tungsten carbide according to any one of claims 1 to 4, characterized in that, After being cooled to room temperature, the plate-shaped coarse tungsten carbide is separated by anodic stripping voltammetry, then washed with water and dried.

6. The method of claim 5, wherein the plate-like tungsten carbide single crystal is prepared by the steps of: preparing a tungsten carbide single crystal by a chemical vapor deposition method; and performing a heat treatment on the tungsten carbide single crystal. The acid used in the anodic stripping voltammetry is dilute hydrochloric acid or dilute sulfuric acid, and the voltage is constant 0.3-1.3V.

7. The plate-shaped super-coarse tungsten carbide single crystal obtained by the preparation method of any one of claims 1-6.

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