A method for preparing high-wear-resistant cemented carbide from returned material

Abstract

The present invention provides a method for preparing high-wear-resistant cemented carbide from return materials. The method comprises mixing the return materials with Cr3C2 powder, VC powder, cobalt powder, and nickel powder to prepare the high-wear-resistant cemented carbide. The cobalt and nickel contents in the raw materials are 13-22 wt%, the sum of the added amounts of the Cr3C2 powder and the VC powder is 0.1-0.5 wt% of the total mass of the raw materials, and the balance is the return materials. The present invention uses return materials of four types of grains, which not only maximizes the processing range of the return materials; the four types of grain raw materials are reasonably matched, Cr3C2 and VC are added, and the deep mixing effect of long-term ball milling can be achieved in 4-6 hours of ball milling without destroying paraffin or PEG. Double-layer 235-mesh sieve wet filtration is used for reasonable impurity removal, SG1.2mm nozzle spraying is adopted, large-tonnage press bidirectional pressing is used, and 1450-1480°C and 6-10MPa pressure sintering is carried out, resulting in a perfect process; the alloy structure is effectively regulated and optimized, and the hardness and transverse rupture strength are simultaneously improved. The product can be used for wear-resistant parts with high wear resistance requirements.

Description

Technical Field

[0001] The invention belongs to the technical field of cemented carbide, and in particular relates to a method for preparing high-wear-resistant cemented carbide from returned materials. Background Art

[0002] In the process of cemented carbide production, it is inevitable to produce a small amount of return materials such as wall cleaning materials, dust collection materials, tailings after product production, waste compacts, and semi-finished product processing scraps, which account for 1.0% to 2.0% of the material input. At present, the main way is to use 10% of the return materials as admixtures after calcination or to remix the entire batch into a low-grade product mixture for downgrading. However, in order to ensure the stability of product quality, the return materials are not allowed to be used as admixtures for fine-grained, ultra-fine-grained products, high-quality medium-grained, and coarse-grained products, and the ways to downgrade them are also very limited. The proportion of raw material costs in the total cost of the cemented carbide industry is very high. Improving the utilization rate of return materials is undoubtedly a very important task. Engineering and technical personnel have made a lot of attempts and explorations for this purpose.

[0003] "Production of Special-Shaped Cemented Carbides by Sanaloi Company of Japan" provides the production of special-shaped cemented carbides. The return material of about 65% is generated during the semi-finished product processing. Through hydrogen reduction, three-time sampling, wax mixing and drying, the prepared mixture can solve the problems of dirtiness and uncertain composition. The mixture has good pressing performance and uniformity. It is a typical traditional method of calcination, dewaxing, impurity removal and then reforming.

[0004] Chinese Patent No. 201610149705.9 discloses a process for producing carbide woodworking blades using fine-particle return material. The process involves dewaxing with a hot water dewaxing solution, adding a molding agent primarily composed of xylene during ball milling, and then pressing, adjusting the dewaxing process, and sintering. The resulting carbide woodworking blades exhibit significantly improved wear resistance and heat resistance, reasonable hardness, and significantly reduced manufacturing costs. The patent's dewaxing process not only increases costs but also inevitably affects the material. The acidic dewaxing solution can significantly corrode elements such as cobalt. Furthermore, the molding agent is very complex and contains more than 10% rubber, making the spraying and dewaxing processes difficult to control. The residual content after dewaxing is relatively high, ultimately affecting alloy performance. The rubber molding agent gradually increases the carbon concentration in the sintering furnace, affecting the alloy's quality stability. Therefore, this patent is not suitable for producing high-quality alloy products.

[0005] Chinese Patent 201610995255.5 discloses a method for producing a mixed material by heating the slurry to above 60°C, filtering it with a screen to remove impurities, and then drying and sieving it. However, this method overlooks a quality risk. The wet grinding process in cemented carbide production strictly controls the temperature of the ball mill. A cooling water jacket is designed in the interlayer of the ball mill to ensure that the water temperature is below 25°C to prevent the material from becoming oxygenated. When the slurry is heated above 60°C, the powder will become significantly oxygenated. The subsequent carbon-oxygen reaction in production will be very complex and difficult to control, which will have a fatal impact on the quality of the alloy. The patent uses a 320-mesh filter to remove paraffin wax. In reality, the paraffin wax is evenly distributed on the surface of the mixture, and incomplete removal makes it difficult to control the paraffin content and the carbon content of the alloy in subsequent production.

[0006] The study "Study on the Process of Dry Ball Grinding Return Material to Produce Cemented Carbide" uses a high ball-to-material ratio and short dry grinding time to crush the return material, achieving the goal of reducing the pressing pressure of the return material and controlling the microstructure. The focus of this paper is on crushing the return material, improving the pressing pressure and microstructure.

[0007] It can be seen from the above patents and literature that the processing of return materials is still mainly based on removing the forming agent, controlling the dirtiness, composition and organizational structure, and improving the pressing performance. The cost of calcining to remove the forming agent is high, dewaxing the dewaxing liquid will have a serious impact on the mixture, and heating the slurry to above 60°C to filter and remove the forming agent will cause the mixture to increase oxygen significantly, which cannot effectively solve the problem of removing impurities from the return material; the method of improving the pressing performance by using special forming agents will not only result in a relatively high residue content after dewaxing, but also cause changes in the carbon atmosphere of the sintering furnace, affecting the quality of the alloy. In fact, there is still no mature way to use the return material.

[0008] Therefore, there is an urgent need for a return material processing method and a high wear-resistant cemented carbide preparation method to solve the above-mentioned problems. Summary of the Invention

[0009] To address the aforementioned issues in the prior art, the present invention proposes a method for producing highly wear-resistant cemented carbide from return materials. This method addresses the bottlenecks of existing cemented carbide production technology, which include the difficulty in handling and controlling return materials and the lack of mature applications. The present invention provides a method for processing and using return materials, effectively managing the return materials and meeting the actual application requirements of the product.

[0010] The present invention proposes a method for preparing high-wear-resistant cemented carbide from returned materials. The method comprises mixing the returned materials with Cr3C2 powder, VC powder, cobalt powder and nickel powder to prepare the high-wear-resistant cemented carbide, wherein the cobalt and nickel contents in the raw materials are 13-22wt%, the sum of the added amounts of the Cr3C2 powder and the VC powder is 0.5-1.5wt% of the total mass of the raw materials; the remainder is the returned materials.

[0011] As a specific embodiment of the present invention, the method comprises the following steps:

[0012] S1: mixing Cr3C2 powder and VC powder and ball milling to obtain a first mixture;

[0013] S2: mixing the first mixture obtained in step S1 and the returned material with ball milling to obtain a second mixture;

[0014] S3: mixing the second mixture obtained in step S2 with cobalt powder and nickel powder, and then ball-milling and filtering to obtain a third mixture;

[0015] S4: drying, granulating, pressing, and sintering the third mixture obtained in step S3 to obtain the high wear-resistant cemented carbide.

[0016] As a specific embodiment of the present invention, the return material includes return material with a grain size of 0.7-1.0μm, return material with a grain size of 1.2-1.6μm, return material with a grain size of 2.0-2.4μm, and return material with a grain size of 2.8-3.6μm; the Fisher particle size of the Cr3C2 powder is 1.0-1.5μm; and the Fisher particle size of the VC powder is 1.0-1.5μm.

[0017] As a specific embodiment of the present invention, based on the total weight of the returned material as 100%, the 0.7-1.0 μm returned material accounts for 30%-50%, the 1.2-1.6 μm returned material accounts for 5%-20%, the 2.0-2.4 μm returned material accounts for 10%-20%, and the 2.8-3.6 μm returned material accounts for 20%-50%.

[0018] According to the present invention, the components of the return material include at least two of Co, Ni, WC, Cr3C2, and VC. In addition to the return material, the raw materials for preparing the high-wear-resistant cemented carbide only use less than 0.5% of Cr3C2 powder and VC powder to adjust the composition. The total amount of Co and Ni in the raw materials is controlled to 13-22wt%, and the total amount of Cr3C2 and VC is controlled to 0.5-1.5wt%.

[0019] As a specific embodiment of the present invention, based on the total mass of the raw materials, the content of cobalt and nickel in the raw materials is 13-22wt%; the content of Cr3C2 powder and VC powder is 0.5-1.5wt%.

[0020] As a specific embodiment of the present invention, the return material includes a molding agent, and the molding agent is paraffin or PEG; the molding agent is paraffin or PEG; the amount of the molding agent is controlled to be 2%-2.3% of the total mass of the raw materials.

[0021] As a specific embodiment of the present invention, the hardness of the cemented carbide is: 82.7-88.5HRA, transverse rupture strength is 2820-3310MPa, and fracture toughness is 17.0-21.0MPa·m -1 / 2 Compared with existing alloys with the same bonding phase content, the hardness is increased by 0.5-3.0HRA and the transverse rupture strength is increased by 500-800 Mpa.

[0022] As a specific embodiment of the present invention, in step S1, the ball milling time is 2-3 hours. The amount of alcohol added for ball milling pretreatment is 250-300 ml of alcohol per kilogram of powder.

[0023] As a specific embodiment of the present invention, in step S2, the ball milling time is 4-6 hours.

[0024] As a specific embodiment of the present invention, in step S3, the filtration includes wet filtration using a sieve, and the model of the sieve is a 235-mesh sieve.

[0025] As a specific embodiment of the present invention, in step S4, the drying includes spray drying. Preferably, the spray drying is performed using a 1.2 mm nozzle at a pressure of 1.1-1.2 MPa.

[0026] As a specific embodiment of the present invention, in step S4, the pressing is performed by bidirectional pressing using a large-tonnage press.

[0027] The sintering is pressure sintering. In step S4, the sintering temperature is 1450-1480° C. and the sintering pressure is 6-10 MPa.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] In the method for preparing high-wear-resistant cemented carbide from return materials of the present invention, return materials of four kinds of grains are used, which not only expands the processing range of the return materials to the maximum extent; the four kinds of grain raw materials are reasonably matched, Cr3C2 and VC are added, and the brand design is reasonable. Ball milling for 4-6 hours can achieve the deep mixing effect of long-term ball milling without destroying paraffin or PEG, double-layer 235-mesh sieve wet filtration is used for reasonable impurity removal, SG1.2mm nozzle spraying, large-tonnage press bidirectional pressing, and 1450-1480°C and 6-10MPa pressure sintering are used, and the process is perfect; the alloy structure is effectively regulated and optimized, the hardness and transverse fracture strength are simultaneously improved, and the fracture toughness is not reduced or slightly reduced. The product can be used for wear-resistant parts with high wear resistance requirements. Judging from the current actual use results, the service life of the product is greatly improved and very stable, and various types of return materials can be effectively processed without degradation. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is a metallographic photograph of the high wear-resistant cemented carbide obtained in Example 1 of the present invention;

[0031] Figure 2 A comparison chart of the hardness of the high wear-resistant cemented carbide prepared in Example 1 of the present invention and the cemented carbides of Comparative Examples 1 and 2;

[0032] Figure 3 A comparison chart of the hardness of the high wear-resistant cemented carbide prepared in Example 3 of the present invention and the cemented carbides of Comparative Examples 3 and 4;

[0033] Figure 4 A comparison chart of the hardness of the high wear-resistant cemented carbide prepared in Example 5 of the present invention and the cemented carbides of Comparative Examples 1 and 2;

[0034] Figure 5 This is a comparison chart of the transverse rupture strength of the high wear-resistant cemented carbide prepared in Example 1 of the present invention and the cemented carbides of Comparative Examples 1 and 2;

[0035] Figure 6 This is a comparison chart of the transverse rupture strength of the high wear-resistant cemented carbide prepared in Example 3 of the present invention and the cemented carbides of Comparative Examples 3 and 4;

[0036] Figure 7 This is a comparison chart of the transverse rupture strength of the high wear-resistant cemented carbide prepared in Example 5 of the present invention and the cemented carbides of Comparative Examples 1 and 2;

[0037] Figure 8 A comparison chart of the fracture toughness of the high wear-resistant cemented carbide prepared in Example 1 of the present invention and the cemented carbides of Comparative Examples 1 and 2;

[0038] Figure 9 This is a comparison chart of the fracture toughness of the high wear-resistant cemented carbide prepared in Example 3 of the present invention and the cemented carbides of Comparative Examples 3 and 4;

[0039] Figure 10 This is a comparison chart of the fracture toughness of the high wear-resistant cemented carbide prepared in Example 5 of the present invention and the cemented carbides of Comparative Examples 1 and 2. DETAILED DESCRIPTION

[0040] The present invention will be further described below with reference to specific examples, but they do not constitute any limitation to the present invention.

[0041] The hardness HRA of the cemented carbide used in the embodiments of the present invention is measured using a Rockwell hardness tester, and the fracture toughness of the alloy with a binder phase content greater than or equal to 15% is measured using an indentation method with a pressure of 100 kg.

[0042] Example 1

[0043] This embodiment provides a method for preparing high wear-resistant cemented carbide from returned materials, the specific details of which are as follows:

[0044] S1: mixing Cr3C2 powder and VC powder and ball milling to obtain a first mixture;

[0045] The total weight percentage of 1.1μm Cr3C2 and 1.3μm VC powders is 0.5%, and 270ml of anhydrous alcohol is added per kilogram of powder and ball milled for 2 hours.

[0046] S2: adding the returned material to the first mixture obtained in step S1, mixing and ball milling to obtain a second mixture;

[0047] Among them, based on the total mass of returned materials, the returned materials with fine grain size of 0.7-1.0μm accounted for 30%, the returned materials with medium grain size of 1.2-1.6μm accounted for 10%, the returned materials with coarse grain size of 2.0-2.4μm accounted for 10%, and the returned materials with coarse grain size of 2.8-3.6μm accounted for 49.5%;

[0048] S3: The second mixture obtained in step S2 is mixed with cobalt powder and nickel powder, ball-milled, and then filtered to obtain a third mixture; the Cr3C2 content in the third mixture is 0.3%, the VC content is 0.2%, the content of the return material with a fine grain size of 0.7-1.0 μm is 23.85%, the content of the return material with a medium grain size of 1.2-1.6 μm is 7.95%, the content of the return material with a coarse grain size of 2.0-2.4 μm is 7.95%, the content of the return material with a coarse grain size of 2.8-3.6 μm is 39.75%, the content of cobalt is 9.5%, and the content of nickel is 10.5%, as shown in Table 1;

[0049] S4: filtering, drying, granulating, pressing, and sintering the third mixture obtained in step S3, wherein the mixture is wet-filtered through a double-layer 235-mesh sieve, spray-dried using an SG1.2mm nozzle, granulated, bidirectionally pressed using a 315-ton press, and sintered at a pressure of 1460°C and 6MPa to obtain the highly wear-resistant cemented carbide.

[0050] The high wear-resistant cemented carbide obtained in Example 1 has a density of 13.45 g / cm 3 , hardness 84.0HRA, transverse rupture strength 3250MPa, fracture toughness 19.6MPa / m 1 / 2 In a metal processing enterprise in Zhangjiagang, Jiangsu, the steel processing single tonnage exceeds 25% of its peers' products, and the wear resistance is higher.

[0051] The metallographic photograph of the high wear-resistant cemented carbide obtained in Example 1 is as follows: Figure 1 As shown, it can be seen that the WC grains are well matched and evenly distributed without other defects.

[0052] Examples 2-6

[0053] Examples 2-6 were prepared according to the steps of Example 1, wherein the conditions are shown in Table 1.

[0054] The high wear-resistant cemented carbide obtained in Example 2 has a density of 14.15 g / cm 3 , hardness 88.5HRA, transverse rupture strength 3100MPa, fracture toughness 17.0MPa / m 1 / 2 In a saw blade manufacturer in Taizhou, Jiangsu, the saw blade rolling capacity reaches 300 tons, which is three times that of the original high-speed steel, with higher wear resistance, service life and cost-effectiveness.

[0055] The high wear-resistant cemented carbide obtained in Example 3 has a density of 14.05 g / cm 3 , hardness 87.5HRA, transverse fracture strength 3230MPa, fracture toughness 18.4MPa / m 1 / 2 In a mold material factory in Zhongshan, Guangdong, it replaced YG15 brand mold material with excellent comprehensive performance, and received positive reviews and repeated orders.

[0056] The high wear-resistant cemented carbide obtained in Example 4 has a density of 13.35 g / cm 3 , hardness 82.7HRA, transverse fracture strength 2820MPa, fracture toughness 21.0MPa / m 1 / 2 At a metal processing company in Yichun, Heilongjiang Province, the output of a single processing operation reached 1.5 times that of the company's existing products, demonstrating better wear resistance.

[0057] The high wear-resistant cemented carbide obtained in Example 5 has a density of 13.48 g / cm 3 , hardness 84.3HRA, transverse fracture strength 3310MPa, fracture toughness 19.8MPa / m 1 / 2 At a machinery equipment company in Mianzhu City, Sichuan Province, the single tonnage of steel processed exceeds 35% of existing products, demonstrating its high wear resistance.

[0058] The high wear-resistant cemented carbide obtained in Example 6 has a density of 14.03 g / cm 3 , hardness 87.0HRA, transverse fracture strength 3150MPa, fracture toughness 18.8MPa / m 1 / 2 In a steel processing enterprise in Xuancheng, Anhui, the service life of the product exceeded 1 / 3 of the original product, and its wear resistance was demonstrated.

[0059] Comparative Examples 1-4

[0060] Comparative Example 1 is a coarse-grained alloy with a grain size of 2.0-2.4 μm and a Co content of 20%.

[0061] Comparative Example 2 is a fine-grained alloy with a grain size of 0.8-1.2 μm and a Co content of 20%.

[0062] Comparative Example 3 is a coarse-grained alloy with a grain size of 2.0-2.4 μm and a Co content of 15%.

[0063] Comparative Example 4 is a fine-grained alloy with a grain size of 0.8-1.2 μm and a Co content of 15%.

[0064] The composition and process parameters of the high wear-resistant cemented carbides prepared in Examples 1-6 of the present invention are tabulated and illustrated as shown in Table 1:

[0065] Table 1

[0066]

[0067] The performance of the high wear-resistant cemented carbides prepared in Examples 1, 3, and 5 of the present invention was compared with that of the cemented carbides prepared in Comparative Examples 1-4. Figure 2-Figure 10 As shown, the hard alloy obtained by the present invention is superior to the hard alloys of Comparative Examples 1-4 in terms of hardness, transverse fracture strength and fracture toughness.

[0068] In summary, the method for preparing high-wear-resistant cemented carbide from return materials of the present invention uses return materials of four kinds of grains, which not only maximizes the processing range of return materials; the reasonable combination of the four kinds of grain raw materials, the addition of Cr3C2 and VC, and the reasonable design of grades, 4-6 hours of ball milling can achieve the deep mixing effect of long-term ball milling without destroying paraffin or PEG, double-layer 235 mesh sieve wet filtration for reasonable impurity removal, SG1.2mm nozzle spraying, large-tonnage press bidirectional pressing, and 1450-1480℃ and 6-10MPa pressure sintering, the process is perfect; effectively regulate and optimize the alloy structure, hardness and transverse fracture strength are improved at the same time, fracture toughness is not reduced or slightly reduced, the product can be used for wear-resistant parts with higher wear resistance requirements, compared with existing products, combined with actual use results, the product service life is greatly improved and very stable, and can effectively and non-degradingly process various types of return materials.

[0069] Any numerical value mentioned in the present invention includes all values ​​that increase by one unit each time from the lowest value to the highest value if there is only a gap of two units between any minimum value and any maximum value. For example, if the amount of a component, or the value of a process variable such as temperature, pressure, time, etc. is stated to be 50-90, it is meant in this specification to specifically list values ​​such as 51-89, 52-88... and 69-71 and 70-71. For non-integer values, it is appropriate to consider units of 0.1, 0.01, 0.001 or 0.0001. These are just some special examples. In this application, in a similar manner, all possible combinations of numerical values ​​between the listed lowest value and the listed highest value are considered to have been disclosed.

[0070] It should be noted that the embodiments described above are only used to explain the present invention and do not constitute any limitation of the present invention. The present invention has been described with reference to typical embodiments, but it should be understood that the words used therein are descriptive and explanatory words, rather than restrictive words. The present invention may be modified as specified within the scope of the claims of the present invention, and the present invention may be revised without departing from the scope and spirit of the present invention. Although the present invention described therein relates to specific methods, materials and embodiments, it does not mean that the present invention is limited to the specific examples disclosed therein. On the contrary, the present invention can be extended to all other methods and applications with the same function.

Claims

1. A method for preparing high wear-resistant cemented carbide from returned materials, characterized in that: The method comprises the steps of mixing the return material with Cr3C2 powder, VC powder, cobalt powder and nickel powder to prepare a high wear-resistant hard alloy; The cobalt and nickel content in the raw materials is 13-22wt%, the sum of the added amounts of the Cr3C2 powder and VC powder is 0.5-1.5wt% of the total mass of the raw materials, and the remainder is the returned material; The return materials include return materials with a grain size of 0.7-1.0 μm, return materials with a grain size of 1.2-1.6 μm, return materials with a grain size of 2.0-2.4 μm, and return materials with a grain size of 2.8-3.6 μm. Based on the total weight of the return materials being 100%, the return materials with a grain size of 0.7-1.0 μm account for 30-50%, the return materials with a grain size of 1.2-1.6 μm account for 5-20%, the return materials with a grain size of 2.0-2.4 μm account for 10-20%, and the return materials with a grain size of 2.8-3.6 μm account for 20-50%. The return materials are wall cleaning materials, dust collection materials, tailings after product production, waste compacts, and semi-finished product processing scraps generated during the cemented carbide production process.

2. The method according to claim 1, characterized in that The following steps are involved: S1: mixing Cr3C2 powder and VC powder and ball milling to obtain a first mixture; S2: mixing the first mixture obtained in step S1 and the returned material with ball milling to obtain a second mixture; S3: mixing the second mixture obtained in step S2 with cobalt powder and nickel powder, and then ball-milling and filtering to obtain a third mixture; S4: drying, granulating, pressing, and sintering the third mixture obtained in step S3 to obtain the high wear-resistant cemented carbide.

3. The method according to claim 1 or 2, characterized in that The Cr3C2 powder has a Fisher particle size of 1.0-1.5 μm; the VC powder has a Fisher particle size of 1.0-1.5 μm.

4. The method according to claim 1 or 2, characterized in that The return material includes a molding agent, which is paraffin or PEG; the amount of the molding agent is controlled to be 2-2.3 wt% of the total mass of the raw materials.

5. The method according to claim 1 or 2, characterized in that The hardness of the cemented carbide is: 82.7-88.5HRA, transverse fracture strength is 2820-3310MPa, and fracture toughness is 17.0-21.0MPa·m -1 / 2 Compared with existing alloys with the same bonding phase content, the hardness is increased by 0.5-3.0HRA and the transverse rupture strength is increased by 500-800 MPa.

6. The method according to claim 2, characterized in that In the step S1, the ball milling time is 2-3 hours; and / or In step S2, the ball milling time is 4-6 hours.

7. The method according to claim 2, characterized in that In step S3, the filtration includes wet filtration using a sieve, and the sieve is a 235-mesh sieve.

8. The method according to claim 2, characterized in that In step S4, the drying comprises spray drying; and / or The sintering is pressure sintering, the sintering temperature is 1450-1480° C., and the sintering pressure is 6-10 MPa.

9. The method according to claim 8, characterized in that In the step S4, a 1.2 mm nozzle is used for spray drying at a pressure of 1.1 to 1.2 MPa.

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