Method for modifying waste hard alloy powder and application

Abstract

The invention relates to the field of recycling of waste hard alloy, in particular to a method for modifying waste hard alloy powder and application. The method comprises the following steps: 1) adding a certain proportion of graphite powder into waste hard alloy powder recovered by an electrochemical method, and then carrying out high-energy ball milling to obtain mixed powder; 2, the mixed powder is subjected to high-temperature carbonization under the inert atmosphere, and the WC-Co composite powder.The method has the advantages that carbon-deficient phases, intermetallic compounds and other impurity phases influencing the hard alloy performance in the waste hard alloy powder can be eliminated, and it is guaranteed that the WC-Co composite powder high in purity, fine in particle size and uniform in particle size distribution is obtained.

Description

Technical Field

[0001] The present invention relates to the field of recycling and reuse of waste cemented carbide, and particularly to a method for modifying waste cemented carbide powder and its application. Background Art

[0002] Cemented carbide has excellent properties such as high strength, high hardness, wear resistance and corrosion resistance, and is applied to important fields such as mechanical manufacturing and energy exploration. However, due to its extremely harsh service environment, a large amount of cemented carbide is discarded, resulting in waste of resources, and it needs to be recycled. At present, there are various recycling methods, but there are many problems with the regenerated cemented carbide powder obtained. In particular, the waste cemented carbide powder obtained by electrochemical recycling has a complex phase and uneven particle size, and cannot be directly used to prepare cemented carbide. Therefore, there is an urgent need to provide a new method for modifying recycled waste cemented carbide powder to solve problems such as complex phase and uneven particle size of the waste alloy powder obtained by electrochemical method, so that it can be directly used to prepare recycled cemented carbide and improve the resource utilization efficiency. Summary of the Invention

[0003] In order to solve the above technical problems, the present invention provides a method for modifying waste cemented carbide powder. The method for modifying waste cemented carbide powder provided by the present invention controls the particle size of the powder by adopting the method of high-energy ball milling - carbonization, combined with optimized ball-to-material ratio, ball milling speed and ball milling time. At the same time, by controlling the carbon ratio, carbonization temperature and inert atmosphere, impurity phases such as carbon-deficient phases and intermetallic compounds that affect the performance of cemented carbide in the waste cemented carbide powder are eliminated, ensuring the obtained WC-Co composite powder with high purity, fine particle size and uniform particle size distribution.

[0004] In the first aspect, the method for modifying waste cemented carbide powder provided by the present invention includes the following steps: 1) Adding a certain proportion of graphite powder to the waste cemented carbide powder recycled by the electrochemical method for high-energy ball milling to obtain a mixed powder.

[0005] 2) Performing high-temperature carbonization on the mixed powder in an inert atmosphere to obtain a WC-Co composite powder. The method for modifying recycled waste cemented carbide powder provided by the present invention can solve problems such as many impurity phases and uneven particle size in the waste cemented carbide powder, thereby obtaining a WC-Co composite powder with high purity, fine particle size and uniform particle size distribution. The method of the present invention can not only effectively eliminate the carbon-deficient phase in the waste cemented carbide powder, but also make the particle size of the WC-Co composite powder more uniform and have properties such as high purity by adopting optimized treatment conditions such as high-energy ball milling and high-temperature carbonization treatment, providing a new technical solution for the high-value utilization of waste cemented carbide powder and having good application prospects.

[0006] Preferably, the addition amount of graphite powder is calculated according to the contents of W and C elements in the waste cemented carbide powder, and the W / C molar ratio (carbon ratio) is 1:1.0 to 1:1.5, preferably 1:1.1 to 1:1.5. For example, 1:1.0, 1:1.2, 1:1.3, 1:1.4, 1:1.5, etc. The most preferred carbon ratio is 1:1.2 to 1:1.4. In the present invention, the ratio of graphite powder is calculated according to the contents of W and C elements in the waste cemented carbide powder. By adding a certain ratio of graphite powder (carbon ratio 1:1.0 to 1:1.5) to the waste cemented carbide powder recovered by the electrochemical method, an unexpected improvement in comprehensive performance can be achieved. Especially under the preferred carbon ratio, it can more effectively eliminate the carbon-deficient phase, intermetallic compounds and other impurity phases that affect the performance of the cemented carbide in the powder, and can well obtain WC-Co composite powder with uniform particle size distribution, which can be directly used for the preparation of recycled cemented carbide subsequently.

[0007] Preferably, the ball-to-material ratio of the high-energy ball milling is 10:1 to 18:1. For example, 10:1, 11:1, 12:1, 13:1, 14:1, 15:1, 16:1, 17:1, etc.

[0008] Preferably, the ball milling speed of the high-energy ball milling is 200 rpm to 500 rpm, and the ball milling time is 8 h to 50 h. By controlling the ball-to-material ratio, ball milling speed and ball milling time to optimize the ball milling process, the present invention can effectively eliminate some carbon-deficient phases existing in the waste cemented carbide powder and make the particle size distribution of the powder more uniform.

[0009] More preferably, the ball milling speed of the high-energy ball milling is 300 rpm to 400 rpm, preferably 350 rpm to 400 rpm, and the ball milling time is 10 h to 30 h, preferably 10 h to 15 h.

[0010] More preferably, the ball-to-material ratio of the high-energy ball milling is 12:1 to 15:1, preferably 14:1 to 15:1.

[0011] Preferably, the carbonization temperature of the high-temperature carbonization is 700°C to 1000°C, and the carbonization time is 0.5 h to 3 h. For example, the carbonization temperature is 700°C, 750°C, 800°C, 850°C, 900°C, 950°C, 980°C, 1000°C, etc.; the carbonization time is 0.5 h, 1 h, 1.2 h, 1.5 h, 2 h, etc. In the present invention, on the basis of optimizing the ratio of graphite powder and ball milling conditions, the carbon-deficient phase in the waste cemented carbide powder can be carbon-supplemented by high-temperature carbonization to obtain a composite powder containing only WC and Co phases. Further optimized high-temperature carbonization parameters can more effectively eliminate the carbon-deficient phase in the waste cemented carbide powder, improve the powder composition uniformity and particle size distribution at the same time, and obtain WC-Co composite powder that can be directly used for the preparation of recycled cemented carbide.

[0012] Further preferably, the carbonization temperature of the high-temperature carbonization is 750 °C to 1000 °C; preferably, the carbonization temperature of the high-temperature carbonization is 800 °C to 1000 °C, and the carbonization time is 1 h to 2 h, preferably 1 h to 1.5 h.

[0013] Further preferably, the inert atmosphere is an argon atmosphere, and the inlet gas flow rate is 200 mL / min to 400 mL / min. By optimizing and controlling the carbonization temperature, carbonization time, and the inert gas argon and its flow rate, the present invention can further eliminate the carbon-deficient phase present in the powder, and improve the powder composition uniformity and particle size distribution.

[0014] Preferably, the addition amount of graphite powder is calculated according to the contents of W and C elements in the waste cemented carbide powder, and the graphite powder and the waste cemented carbide powder recovered by the electrochemical method are simultaneously put into a ball milling tank, and high-energy ball milling is carried out by using a planetary ball mill.

[0015] In a second aspect, the present invention provides a WC-Co composite powder obtained by the method for modifying the recovered waste cemented carbide powder. The method of the present invention can obtain a WC-Co composite powder with high purity, and better powder composition uniformity and particle size distribution, and can be directly used for preparing a harder recycled cemented carbide.

[0016] In a third aspect, the present invention provides a cemented carbide, and the raw material of the cemented carbide includes the WC-Co composite powder obtained by the method for modifying the waste cemented carbide powder.

[0017] In a fourth aspect, the present invention provides the application of the WC-Co composite powder obtained by the method for modifying the waste cemented carbide powder or the above WC-Co composite powder in the preparation of a cemented carbide. The method for modifying the waste cemented carbide powder provided by the present invention is innovative, and is more feasible and environmentally friendly in actual operation. The present invention provides a new method with a simple process, environmental protection and high efficiency for modifying the waste cemented carbide powder, and also provides new ideas for the high-value utilization of the waste cemented carbide powder.

[0018] The beneficial effects of the present invention are at least as follows: The present invention uses the waste cemented carbide powder recovered by the electrochemical method and graphite powder as raw materials, and modifies the complex impurity phases and uneven particle sizes existing in the above powders through high-energy ball milling-carbonization treatment to obtain a WC-Co composite powder with high purity. By optimizing the ball-to-material ratio, ball milling speed, and ball milling time, the ball milling efficiency is improved, and the problem of uneven particle size of the powder is improved; by optimizing the carbonization temperature and carbonization time, the carbon-deficient phase, intermetallic compounds and other impurity phases that affect the performance of the cemented carbide existing in the waste cemented carbide powder can be effectively eliminated, and a WC-Co composite powder with high purity, fine particle size and uniform particle size distribution can be ensured. Description of the Drawings

[0019] To more clearly illustrate the technical solutions in the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0020] Figure 1 Schematic diagram of a scanning electron microscope of the powder after ball milling provided in Embodiment 1 of the present invention.

[0021] Figure 2 Schematic diagram of the X-ray diffraction result of the powder after carbonization provided in Embodiment 1 of the present invention.

[0022] Figure 3 Schematic diagram of a scanning electron microscope of the powder after carbonization provided in Embodiment 1 of the present invention. Detailed implementation manners

[0023] To make the objectives, technical solutions, and advantages of the present invention clearer, the following will clearly and completely describe the technical solutions in the present invention. Obviously, the described embodiments are some embodiments of the present invention, rather than all of them. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of the present invention.

[0024] In the ranges disclosed in the present invention, the endpoints and any values are not limited to the precise ranges or values. These ranges or values should be understood to include values close to these ranges or values. For numerical ranges, between the endpoint values of each range, between the endpoint values of each range and individual point values, and between individual point values, they can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed in the present invention.

[0025] In the embodiments of the present invention, for those not specifying specific technologies or conditions, they shall be in accordance with the technologies or conditions described in the literature in this field or in accordance with the product instructions. For devices, instruments, reagents, etc. not specifying the manufacturer, they are all conventional products that can be obtained through regular channels. The experimental reagents and raw materials involved are all commercially available products, and the reagents are all analytical pure products.

[0026] In the embodiments of the present invention, the particle size distribution range of the waste cemented carbide powder recovered by the electrochemical method is 1 - 20 µm, and the specific components are as follows in the table.

[0027] Table 1 Composition of waste cemented carbide powder (wt.%)

[0028] Example 1 This example provides a method for modifying waste cemented carbide powder, and the specific formula is as follows: Table 2 Composition of the mixed powder before ball milling

[0029] High-energy ball milling: Weigh 50.08 g of waste cemented carbide powder and 2.52 g of graphite powder under the conditions of a ball-to-material ratio of 15:1 and a carbon ratio (molar ratio of W / C) of 1:1.2. After mixing, place them in a ball milling tank and perform ball milling using a planetary ball mill. The ball milling speed is 400 rpm, and the ball milling time is 10 h to obtain a mixed powder.

[0030] The scanning electron microscope results of the powder after ball milling are as Figure 1 shown.

[0031] High-temperature carbonization: Use a tube furnace to perform carbonization treatment on the ball-milled powder in an argon atmosphere. The inlet gas flow rate is 200 mL / min, the carbonization temperature is 850 °C, and the carbonization time is 1 h.

[0032] After the carbonization is completed, a WC-Co composite powder is obtained.

[0033] The X-ray diffraction results of the WC-Co composite powder obtained by carbonization are as Figure 2 shown, and the scanning electron microscope results are as Figure 3 shown.

[0034] Example 2 This example provides a method for modifying waste cemented carbide powder, and the specific formula is as follows: Table 3 Composition of the mixed powder before ball milling

[0035] High-energy ball milling: Weigh 50.08 g of waste cemented carbide powder and 2.52 g of graphite powder under the conditions of a ball-to-material ratio of 15:1 and a carbon ratio of 1:1.2. After mixing, place them in a ball milling tank and perform ball milling using a planetary ball mill. The ball milling speed is 400 rpm, and the ball milling time is 10 h to obtain a mixed powder.

[0036] High-temperature carbonization: Use a tube furnace to perform carbonization treatment on the ball-milled powder in an argon atmosphere. The inlet gas flow rate is 200 mL / min, the carbonization temperature is 950 °C, and the carbonization time is 1 h.

[0037] After the carbonization is completed, a WC-Co composite powder is obtained.

[0038] Example 3 This example provides a method for modifying waste cemented carbide powder, and the specific formula is as follows: Table 4 Composition of the mixed powder before ball milling

[0039] High-energy ball milling: Weigh 50.08 g of waste cemented carbide powder and 2.52 g of graphite powder under the conditions of a ball-to-material ratio of 15:1 and a carbon ratio of 1:1.2. After mixing, place them in a ball milling tank and use a planetary ball mill for ball milling. The ball milling speed is 400 rpm and the ball milling time is 10 h to obtain a mixed powder.

[0040] High-temperature carbonization: Use a tube furnace to perform carbonization treatment on the ball-milled powder under an argon atmosphere. The inlet gas flow rate is 200 mL / min, the carbonization temperature is 800 °C, and the carbonization time is 1 h.

[0041] After the carbonization is completed, WC-Co composite powder is obtained.

[0042] Example 4 This example provides a method for modifying waste cemented carbide powder, which is as follows: Table 5 Composition of the mixed powder before ball milling

[0043] High-energy ball milling: Weigh 50.08 g of waste cemented carbide powder and 2.52 g of graphite powder under the conditions of a ball-to-material ratio of 15:1 and a carbon ratio of 1:1.2. After mixing, place them in a ball milling tank and use a planetary ball mill for ball milling. The ball milling speed is 400 rpm and the ball milling time is 10 h to obtain a mixed powder.

[0044] High-temperature carbonization: Use a tube furnace to perform carbonization treatment on the ball-milled powder under an argon atmosphere. The inlet gas flow rate is 200 mL / min, the carbonization temperature is 750 °C, and the carbonization time is 1 h.

[0045] After the carbonization is completed, WC-Co composite powder is obtained.

[0046] Example 5 This example provides a method for modifying waste cemented carbide powder, and the specific formula is as follows: Table 6 Composition of the mixed powder before ball milling

[0047] High-energy ball milling: Weigh 50.08 g of waste cemented carbide powder and 2.52 g of graphite powder under the conditions of a ball-to-material ratio of 15:1 and a carbon ratio of 1:1.2. After mixing, place them in a ball milling tank and use a planetary ball mill for ball milling. The ball milling speed is 400 rpm and the ball milling time is 10 h to obtain a mixed powder.

[0048] High-temperature carbonization: The milled powder was carbonized in a tubular furnace under an argon atmosphere. The inlet gas flow rate was 200 mL / min, the carbonization temperature was 700 °C, and the carbonization time was 1 h.

[0049] After carbonization, WC-Co composite powder was obtained.

[0050] Example 6 This example provides a method for modifying waste cemented carbide powder, and the specific formula is as follows: Table 7 Composition of the mixed powder before ball milling

[0051] High-energy ball milling: Under the conditions of a ball-to-material ratio of 15:1 and a carbon ratio of 1:1.4, 49.34 g of waste cemented carbide powder and 3.26 g of graphite powder were weighed, mixed and placed in a ball milling tank. A planetary ball mill was used for ball milling. The ball milling speed was 400 rpm, and the ball milling time was 10 h to obtain a mixed powder.

[0052] High-temperature carbonization: The milled powder was carbonized in a tubular furnace under an argon atmosphere. The inlet gas flow rate was 200 mL / min, the carbonization temperature was 1000 °C, and the carbonization time was 1 h.

[0053] After carbonization, WC-Co composite powder was obtained.

[0054] Comparative Example 1 Comparative Example 1 provides a method for modifying waste cemented carbide powder, which is different from the example in that no high-temperature carbonization treatment is carried out. The details are as follows: High-energy ball milling: Under the conditions of a ball-to-material ratio of 15:1 and a carbon ratio of 1:1.0, 50.60 g of waste cemented carbide powder and 2.10 g of graphite powder were weighed, mixed and placed in a ball milling tank. A planetary ball mill was used for ball milling. The ball milling speed was 400 rpm, and the ball milling time was 50 h to obtain a mixed powder.

[0055] Comparative Example 2 Comparative Example 2 provides a method for modifying waste cemented carbide powder, which is different from the example in that no high-energy ball milling treatment is carried out. The details are as follows: High-temperature carbonization: Under the condition of a carbon ratio of 1:1.4, 5.00 g of waste cemented carbide powder and 0.30 g of graphite powder were weighed, thoroughly ground and placed in a corundum boat. A tubular furnace was used to carbonize the above powder under an argon atmosphere. The inlet gas flow rate was 200 mL / min, the carbonization temperature was 950 °C, and the carbonization time was 1 h. After carbonization, the product powder was obtained.

[0056] Experimental Example 1 The WC-Co composite powder obtained after carbonization in Example 6 was sintered into a cemented carbide block using a spark plasma sintering furnace, and the density, hardness, and fracture toughness of the block were tested.

[0057] The hardness and fracture toughness of the cemented carbide block are shown in Table 8.

[0058] Table 8 Mechanical properties of WC-Co cemented carbide blocks

[0059] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for modifying waste cemented carbide powder, characterized in that It includes the following steps: 1) Add a certain proportion of graphite powder to the waste cemented carbide powder recovered by the electrochemical method and perform high-energy ball milling to obtain a mixed powder; 2) Carry out high-temperature carbonization on the mixed powder under an inert atmosphere to obtain a WC-Co composite powder.

2. The method for modifying waste cemented carbide powder according to claim 1, characterized in that Calculate the addition amount of graphite powder according to the contents of W and C elements in the waste cemented carbide powder, and the carbon molar ratio is 1:1.0 to 1:1.5, preferably 1:1.1 to 1:1.

5.

3. The method for modifying waste cemented carbide powder according to claim 2, characterized in that, The ball-to-material ratio of the high-energy ball milling is 10:1 to 18:

1.

4. The method for modifying waste cemented carbide powder according to any one of claims 1-3, characterized in that, The ball milling speed of the high-energy ball milling is 200 rpm to 500 rpm, and the ball milling time is 8 h to 50 h; Preferably, the ball milling speed of the high-energy ball milling is 300 rpm to 400 rpm, and the ball milling time is 10 h to 30 h.

5. The method for modifying waste cemented carbide powder according to claim 4, characterized in that, The ball-to-material ratio of the high-energy ball milling is 12:1 to 15:1, preferably 14:1 to 15:

1.

6. The method for modifying waste cemented carbide powder according to any one of claims 1-5, characterized in that, The carbonization temperature of the high-temperature carbonization is 700 °C to 1000 °C, and the carbonization time is 0.5 h to 3 h; Preferably, the carbonization temperature of the high-temperature carbonization is 750 °C to 1000 °C, and the carbonization time is 1 h to 2 h.

7. The method for modifying waste cemented carbide powder according to any one of claims 1-6, characterized in that The inert atmosphere is an argon atmosphere, and the inlet gas flow rate is 200 mL / min to 400 mL / min.

8. The WC-Co composite powder obtained by the method for modifying the waste cemented carbide powder according to any one of claims 1-7.

9. A cemented carbide, characterized in that, The raw material of the cemented carbide includes the WC-Co composite powder obtained by the method for modifying the waste cemented carbide powder according to any one of claims 1-7.

10. The application of the WC-Co composite powder obtained by the method for modifying the waste cemented carbide powder according to any one of claims 1-7 or the WC-Co composite powder according to claim 8 in the preparation of cemented carbide.

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