A method for preparing WC powder and WC-Co alloy using a high-temperature gradient carbonization process.

Abstract

The application discloses a kind of WC powder and WC-Co alloy prepared by high-temperature gradient carbonization process, and relates to the technical field of hard alloy.Adopt tungsten powder and carbon source as raw material, after ball milling and mixing, first carbonization is carried out at 800-900 DEG C, then second carbonization is carried out at 900-1100 DEG C, continue third carbonization is carried out at 1100-1150 DEG C, then fourth carbonization is carried out at 1150-1350 DEG C, finally fifth carbonization is carried out at 1350-1500 DEG C, and is prepared.The tungsten carbide powder prepared by the application presents excellent dispersity, only a small amount of fine nano-agglomerated particles, and the agglomerated particles are loose and porous, and the alloy performance is more excellent.

Description

Technical Field

[0001] This invention relates to the field of cemented carbide technology, specifically to a method for preparing WC powder and WC-Co alloy using a high-temperature gradient carbonization process. Background Technology

[0002] Ultrafine / nanocrystalline alloy products are a research hotspot in aerospace, communications, and electronics fields due to their excellent high strength, high hardness, good wear / corrosion resistance, and resistance to brittle fracture. Currently, high-purity WC powder or WC-Co composite powder with concentrated particle size distribution, intact crystals, and good temperature sensitivity are typically used as raw materials, with the addition of appropriate inhibitors, combined with trace element modification technology and novel sintering techniques to prepare ultrafine-grained cemented carbides. The preparation of ultrafine / nanocrystalline WC powder generally employs a stepwise hydrogen reduction carbonization process or a carbon-assisted direct-heat hydrogen reduction carbonization process, requiring low oxygen content, good chemical stability, narrow particle size distribution, and low impurity content in the W powder. Therefore, the process requires further improvement. Summary of the Invention

[0003] The purpose of this invention is to at least solve one of the technical problems existing in the prior art, and to provide a method for preparing WC powder and WC-Co alloy using a high-temperature gradient carbonization process.

[0004] The technical solution of the present invention is as follows:

[0005] A method for preparing WC powder using a high-temperature gradient carbonization process includes the following steps: using tungsten powder and carbon source as raw materials, ball milling and mixing them, performing a first carbonization at 800-900℃, then a second carbonization at 900-1100℃, continuing with a third carbonization at 1100-1150℃, then a fourth carbonization at 1150-1350℃, and finally a fifth carbonization at 1350-1500℃ to obtain the powder.

[0006] As a preferred embodiment of the present invention, the first carbonization time is 10-40 min, the second carbonization time is 50-60 min, the third carbonization time is 20-40 min, the fourth carbonization time is 10-30 min, and the fifth carbonization time is 10-30 min.

[0007] As a preferred embodiment of the present invention, a mixture of methane and hydrogen gas is introduced during the fifth carbonization.

[0008] As a preferred embodiment of the present invention, the carbon source is porous carbon, and its preparation method is as follows:

[0009] Diatomaceous earth is added to furfuryl alcohol, mixed evenly, and then heated under vacuum at 90-100℃ for 1-5 hours. Then it is sintered at 600-800℃ in an inert atmosphere for 1-3 hours, then treated with alkaline solution for 10-30 minutes, washed, and dried to obtain the final product.

[0010] As a preferred embodiment of the present invention, the tungsten powder is blue tungsten and / or purple tungsten.

[0011] As a preferred embodiment of the present invention, the Fess particle size of the tungsten powder is 0.1-0.6 μm.

[0012] The present invention also discloses a WC powder, characterized in that it is prepared by any one of the preparation methods described in claims 1-6.

[0013] The present invention also discloses a WC-Co alloy, which uses WC powder as described above as a raw material.

[0014] The beneficial effects of this invention are as follows: the tungsten carbide powder prepared using blue tungsten and / or purple tungsten exhibits excellent dispersibility, with only a small number of fine nano-agglomerates. These agglomerates are loose and porous, and the porous structure of purple tungsten facilitates contact with gases and the removal of other gases during the carbonization process. Simultaneously, the use of a porous carbon source further enhances contact with the reducing atmosphere during carbonization, resulting in better carburizing and reduction effects and superior performance. Attached Figure Description

[0015] Figure 1 SEM of Example 3;

[0016] Figure 2 This is the SEM for comparative example 1. Detailed Implementation

[0017] The embodiments of the present invention are described in detail below. These embodiments are exemplary and are only used to explain the present invention, and should not be construed as limiting the invention. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in the art or according to the product instructions. Reagents or instruments used, unless otherwise specified, are all commercially available conventional products.

[0018] Example 1

[0019] A method for preparing WC powder using a high-temperature gradient carbonization process includes the following steps: using tungsten powder and carbon source as raw materials, ball milling and mixing them, performing a first carbonization at 800℃, then a second carbonization at 900℃, continuing with a third carbonization at 1100℃, followed by a fourth carbonization at 1150-1350℃, and finally a fifth carbonization at 1350℃ to obtain the powder.

[0020] The first carbonization time is 10 minutes, the second carbonization time is 50 minutes, the third carbonization time is 40 minutes, the fourth carbonization time is 10 minutes, and the fifth carbonization time is 10 minutes.

[0021] A 1:1 mixture of methane and hydrogen gas is introduced during the fifth carbonization process.

[0022] The carbon source is porous carbon, and its preparation method is as follows:

[0023] Diatomaceous earth was added to furfuryl alcohol and mixed evenly. The mixture was then heated under vacuum at 90°C for 3 hours, sintered at 600°C under an inert atmosphere for 1 hour, treated with alkali solution for 10 minutes, washed, and dried to obtain the final product.

[0024] The tungsten powder is blue tungsten.

[0025] The Fess particle size of the tungsten powder is 0.5 μm.

[0026] Example 2

[0027] A method for preparing WC powder using a high-temperature gradient carbonization process includes the following steps: using tungsten powder and carbon source as raw materials, ball milling and mixing them, performing a first carbonization at 900℃, then a second carbonization at 1100℃, continuing with a third carbonization at 1150℃, followed by a fourth carbonization at 1350℃, and finally a fifth carbonization at 1500℃ to obtain the powder.

[0028] The first carbonization time is 20 minutes, the second carbonization time is 50 minutes, the third carbonization time is 30 minutes, the fourth carbonization time is 20 minutes, and the fifth carbonization time is 30 minutes.

[0029] A mixture of methane and hydrogen in a 1:1 volume ratio is introduced during the fifth carbonization process.

[0030] The carbon source is porous carbon, and its preparation method is as follows:

[0031] Diatomaceous earth was added to furfuryl alcohol and mixed evenly. The mixture was then heated under vacuum at 90°C for 3 hours, sintered at 600°C under an inert atmosphere for 1 hour, treated with alkali solution for 10 minutes, washed, and dried to obtain the final product.

[0032] The tungsten powder is blue tungsten.

[0033] The Fess particle size of the tungsten powder is 0.5 μm.

[0034] Example 3

[0035] A method for preparing WC powder using a high-temperature gradient carbonization process includes the following steps: using tungsten powder and carbon source as raw materials, ball milling and mixing them, performing a first carbonization at 850℃, then a second carbonization at 1100℃, continuing with a third carbonization at 1150℃, followed by a fourth carbonization at 1250℃, and finally a fifth carbonization at 1400℃ to obtain the powder.

[0036] The first carbonization time is 30 minutes, the second carbonization time is 50 minutes, the third carbonization time is 30 minutes, the fourth carbonization time is 20 minutes, and the fifth carbonization time is 10 minutes.

[0037] A mixture of methane and hydrogen in a 1:1 volume ratio is introduced during the fifth carbonization process.

[0038] The carbon source is porous carbon, and its preparation method is as follows:

[0039] Diatomaceous earth was added to furfuryl alcohol and mixed evenly. The mixture was then heated under vacuum at 90°C for 3 hours, sintered at 600°C under an inert atmosphere for 1 hour, treated with alkali solution for 10 minutes, washed, and dried to obtain the final product.

[0040] The tungsten powder is blue tungsten.

[0041] The Fess particle size of the tungsten powder is 0.5 μm.

[0042] Example 4

[0043] A method for preparing WC powder using a high-temperature gradient carbonization process includes the following steps: using tungsten powder and carbon source as raw materials, ball milling and mixing them, performing a first carbonization at 850℃, then a second carbonization at 1100℃, continuing with a third carbonization at 1150℃, followed by a fourth carbonization at 1250℃, and finally a fifth carbonization at 1400℃ to obtain the powder.

[0044] The first carbonization time is 30 minutes, the second carbonization time is 50 minutes, the third carbonization time is 30 minutes, the fourth carbonization time is 20 minutes, and the fifth carbonization time is 10 minutes.

[0045] A mixture of methane and hydrogen in a 1:1 volume ratio is introduced during the fifth carbonization process.

[0046] The carbon source is porous carbon, and its preparation method is as follows:

[0047] Diatomaceous earth was added to furfuryl alcohol and mixed evenly. The mixture was then heated under vacuum at 90°C for 3 hours, sintered at 600°C under an inert atmosphere for 1 hour, treated with alkali solution for 10 minutes, washed, and dried to obtain the final product.

[0048] The tungsten powder is purple tungsten.

[0049] The Fess particle size of the tungsten powder is 0.5 μm.

[0050] Example 5

[0051] A method for preparing WC powder using a high-temperature gradient carbonization process includes the following steps: using tungsten powder and carbon source as raw materials, ball milling and mixing them, performing a first carbonization at 850℃, then a second carbonization at 1100℃, continuing with a third carbonization at 1150℃, followed by a fourth carbonization at 1250℃, and finally a fifth carbonization at 1400℃ to obtain the powder.

[0052] The first carbonization time is 30 minutes, the second carbonization time is 50 minutes, the third carbonization time is 30 minutes, the fourth carbonization time is 20 minutes, and the fifth carbonization time is 10 minutes.

[0053] A mixture of methane and hydrogen in a 1:1 volume ratio is introduced during the fifth carbonization process.

[0054] The carbon source is porous carbon, and its preparation method is as follows:

[0055] Diatomaceous earth was added to furfuryl alcohol and mixed evenly. The mixture was then heated under vacuum at 90°C for 3 hours, sintered at 600°C under an inert atmosphere for 1 hour, treated with alkali solution for 10 minutes, washed, and dried to obtain the final product.

[0056] The tungsten powder is a mixture of blue tungsten and purple tungsten in a 1:1 mass ratio.

[0057] The Fess particle size of the tungsten powder is 0.5 μm.

[0058] Comparative Example 1

[0059] A method for preparing WC powder using a high-temperature gradient carbonization process includes the following steps: using tungsten powder and carbon source as raw materials, ball milling and mixing, and then carbonizing at 1450℃ for 120 min.

[0060] The carbon source is porous carbon, and its preparation method is as follows:

[0061] Diatomaceous earth was added to furfuryl alcohol and mixed evenly. The mixture was then heated under vacuum at 90°C for 3 hours, sintered at 600°C under an inert atmosphere for 1 hour, treated with alkali solution for 10 minutes, washed, and dried to obtain the final product.

[0062] The tungsten powder is a mixture of blue tungsten and purple tungsten in a 1:1 mass ratio.

[0063] The Fess particle size of the tungsten powder is 0.5 μm.

[0064] Comparative Example 2

[0065] A method for preparing WC powder using a high-temperature gradient carbonization process includes the following steps: using tungsten powder and carbon source as raw materials, ball milling and mixing them, performing a first carbonization at 850℃, then a second carbonization at 1100℃, continuing with a third carbonization at 1150℃, followed by a fourth carbonization at 1250℃, and finally a fifth carbonization at 1400℃ to obtain the powder.

[0066] The first carbonization time is 30 minutes, the second carbonization time is 50 minutes, the third carbonization time is 30 minutes, the fourth carbonization time is 20 minutes, and the fifth carbonization time is 10 minutes.

[0067] A mixture of methane and hydrogen in a 1:1 volume ratio is introduced during the fifth carbonization process.

[0068] The carbon source is carbon black.

[0069] The Fess particle size of the tungsten powder is 0.5 μm.

[0070] Using WC powder as described above as raw material, 6wt% Co was added, and the mixture was ball-milled, formed into blanks, and sintered to obtain the final product.

[0071] Microscopic SEM images of the sample from Example 3 show that the WC structure is loose, uniformly dispersed, with fine particles, high degree of carbonization, and few lattice defects.

[0072] Microscopic SEM images of the sample from Comparative Example 1 show that there is a small amount of aggregation and dispersion, which is worse than that of the Example.

[0073] Meanwhile, the properties of the prepared WC-Co alloy were tested, and the test results are shown in Table 1.

[0074] Table 1. Performance test results of the examples and comparative examples.

[0075] Sample <![CDATA[Coercive force (A.m -1 )]]> Hardness (HRA) Flexural strength (MPa) Example 1 42500 93.6 4221 Example 2 42200 93.8 4260 Example 3 42300 93.5 4321 Example 4 42100 93.1 4251 Example 5 42600 93.8 4236 Comparative Example 1 40210 91.2 4013 Comparative Example 2 41000 92.3 4120

[0076] As can be seen from the table above, the performance of the examples is superior to that of the comparative examples. The possible reasons are as follows: the tungsten carbide powder prepared using blue tungsten and / or purple tungsten exhibits excellent dispersibility, with only a small number of fine nano-agglomerates. These agglomerates are loose and porous, and the porous structure of purple tungsten facilitates contact with gases and the removal of other gases during the carbonization process. Simultaneously, the use of a porous carbon source further facilitates contact with the reducing atmosphere during carbonization, resulting in better carburizing and reduction effects, thus leading to superior performance.

[0077] Without causing conflict, those skilled in the art can freely combine and use the above-mentioned additional technical features.

[0078] The embodiments described above are merely preferred embodiments of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various other corresponding changes and modifications based on the technical solutions and concepts described above, and all such changes and modifications should fall within the protection scope of the claims of the present invention.

Claims

1. A method for producing WC powder by a high temperature gradient carbonization process, characterized by, The method comprises the following steps: The tungsten powder and a carbon source are mixed uniformly by ball milling, and then subjected to first carbonization at 800-900 DEG C, second carbonization at 900-1100 DEG C, third carbonization at 1100-1150 DEG C, fourth carbonization at 1150-1350 DEG C, and fifth carbonization at 1350-1500 DEG C to obtain the WC powder; The carbon source is porous carbon, and the preparation method is as follows: Diatomite is added into furfuryl alcohol, mixed uniformly, vacuum heated at 90-100 DEG C for 1-5 h, sintered at 600-800 DEG C under inert atmosphere for 1-3 h, then treated with alkali solution for 10-30 min, washed, and dried to obtain the porous carbon; The tungsten powder is blue tungsten and / or purple tungsten.

2. The method of claim 1, wherein the WC powder is prepared by a high-temperature gradient carbonization process. The first carbonization time is 10-40 min, the second carbonization time is 50-60 min, the third carbonization time is 20-40 min, the fourth carbonization time is 10-30 min, and the fifth carbonization time is 10-30 min.

3. The method of claim 1, wherein the WC powder is prepared by a high-temperature gradient carbonization process. The mixed gas of methane and hydrogen is introduced during the five carbonization processes.

4. The method of claim 1, wherein the WC powder is prepared by a high-temperature gradient carbonization process. The Fess particle size of the tungsten powder is 0.1-0.6 μm.

5. A WC powder, characterized in that, The WC powder is prepared by the preparation method of any one of claims 1-4.

6. A WC-Co alloy, characterized by, The WC powder prepared by the preparation method of claim 5 is used as the raw material.

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