Nano hard alloy and preparation method thereof
By designing new bonding phase components and high entropy bonding phases, the problem of grain growth in nanocarbide carbide during sintering is solved, and the preparation of nanocarbide carbide without adding grain inhibitors is realized, which improves the mechanical properties and structural density of cemented carbide.
Patent Information
- Application Number
- CN202510394694.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-31
- Publication Date
- 2025-06-17
AI Technical Summary
During the sintering process, existing nanocarbides are prone to lose their nanocrystalline characteristics due to grain growth, resulting in tissue structure defects and performance degradation, and grain inhibitors are required to control growth.
The new bonding phase component design is adopted, including Co, Ni, Fe and Cr, Re, Ru, Os and other components. By defining the components and content of the bonding phase, the carbon content is reduced, the WC grain growth is inhibited, and the liquid phase sintering is formed through the high-entropy bonding phase, which hinders the movement of W and C atoms and controls the grain size.
Without adding grain inhibitors, the growth of nanoWC grains is effectively controlled, the "ball grinding state" of the nano hard phase is maintained, the hardness, strength and comprehensive mechanical properties of cemented carbide are improved, and the process is simple, suitable for large-scale industrial production.
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Figure CN120158664A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of cemented carbides, and particularly relates to a nano-cemented carbide and a preparation method thereof. Background Art
[0002] Compared with ordinary cemented carbides, nano-cemented carbides have significantly improved comprehensive properties, such as high hardness and high strength. Nano-cemented carbide products have been widely used in fields such as automobiles, aerospace, energy, electronic communications, and new energy manufacturing. However, the preparation process of nano-cemented carbides is complex. The biggest difficulty is that the nano-cemented carbide powder grows rapidly during the sintering process, losing its nano-crystalline characteristics. Therefore, it is necessary to add grain growth inhibitors. However, the specific surface area of nano-powders is large and the surface activity is strong. Despite the addition of grain inhibitors, the nano-powders are still prone to abnormal growth during the sintering process, resulting in organizational structure defects and affecting the comprehensive properties of the cemented carbides. Summary of the Invention
[0003] The technical problem to be solved by the present invention is to overcome the deficiencies of the prior art and provide a nano-cemented carbide with a novel binder phase replacing the cobalt binder phase, high density, uniform organizational structure, and good mechanical properties. Correspondingly, the present invention also provides a preparation method of a nano-cemented carbide that does not require the addition of grain inhibitors, can effectively inhibit grain growth, and is simple and convenient.
[0004] To solve the above technical problems, the present invention adopts the following technical solutions.
[0005] A nano-cemented carbide includes a binder phase and a nano-carbide phase. The mass fraction of the binder phase is 8% - 18%, and the rest is the nano-carbide phase (i.e., the mass fraction is 92% - 82%). The components of the binder phase include a first component (also referred to as the first component group), a second component (also referred to as the second component group), and a W component. The first component is at least one of Co, Ni, and Fe. The second component is at least two of Cr, Re, Ru, Rh, Pd, Os, Ir, and Pt. And the total number of components of the first component and the second component is at least 5;
[0006] The components of the binder phase satisfy the condition: X≥0.40,
[0007] X = [(a Cr +a Re +a Ru +a Rh +a Pd +a Os +a Ir +a Pt ) / n] / [(a Co +a Ni +a Fe ) / m] Formula (1)
[0008] In formula (1), a Cr , a Re , a Ru , a Rh , a Pd , a Os , a Ir , a Pt are respectively the atomic percentages of Cr, Re, Ru, Rh, Pd, Os, Ir, and Pt in all components of the binder phase, n is the number of components of the second component, a Co , a Ni , a Fe are respectively the atomic percentages of Co, Ni, and Fe in all components of the binder phase, m is the number of components of the first component, and the atomic percentages of each component in the first component and each component in the second component in all components of the binder phase are 5% to 35%. a w is the atomic percentage of the W component in all components of the binder phase, and the value range of a w is 5% to 35%.
[0009] For the above-mentioned nano-cemented carbide, preferably, 0.40 ≤ X ≤ 1.50.
[0010] For the above-mentioned nano-cemented carbide, preferably, a w has a value range of 7% to 15%.
[0011] For the above-mentioned nano-cemented carbide, preferably, the mixing entropy of all components of the binder phase satisfies the condition: mixing entropy △S mix ≥ 1.51R, where R is the molar gas constant,
[0012]
[0013] In formula (2), N is the total number of atoms of all components of the binder phase, n1 to n r are respectively the number of atoms of each component in the binder phase, r is the number of all components of the binder phase, and k is the Boltzmann constant.
[0014] For the above-mentioned nano-cemented carbide, preferably, the mixing entropy △S mix ≥ 1.61R.
[0015] For the above-mentioned nano-cemented carbide, preferably, the nano-hard phase is a WC phase, and the average grain size of the WC phase is less than 0.2 μm.
[0016] As a general technical concept, the present invention also provides a preparation method of the above-mentioned nano-cemented carbide, including the following steps:
[0017] (1) Prepare WC powder, the first raw material powder, and the second raw material powder. The first raw material powder is at least one of Co powder, Ni powder, and Fe powder, and the second raw material powder is at least two of Cr3C2 powder, Re powder, Ru powder, Rh powder, Pd powder, Os powder, Ir powder, and Pt powder. The total number of raw materials of the first raw material powder and the second raw material powder is at least five. First, perform pre-ball milling on the WC powder, and then add the first raw material powder and the second raw material powder and ball mill them evenly to obtain a mixture.
[0018] (2) Dry and granulate the mixture, then press it into a shape, and then perform hydrogen dewaxing, sintering, and cooling to obtain a nano-cemented carbide.
[0019] For the above method for preparing nano-cemented carbide, preferably, in step (1), the Fsss particle sizes of the Co powder, Ni powder, and Fe powder are all ≤ 0.5 μm, the Fsss particle sizes of the Cr3C2 powder, Re powder, Ru powder, Rh powder, Pd powder, Os powder, Ir powder, and Pt powder are all ≤ 1 μm, the Fsss particle size of the WC powder is ≤ 0.4 μm. After the WC powder undergoes pre-ball milling, the Fsss particle size of the pre-ball milled WC powder is < 0.2 μm, and the Fsss particle size of the pre-ball milled WC powder is < the Fsss particle size of the WC powder.
[0020] For the above method for preparing nano-cemented carbide, preferably, in step (1), the time for pre-ball milling is 30 h to 80 h, and the time for ball milling is 20 h to 50 h.
[0021] For the above method for preparing nano-cemented carbide, preferably, in step (1), the purity of the WC powder is not less than 99.9%, and the purities of the Co powder, Ni powder, Fe powder, Cr3C2 powder, Re powder, Ru powder, Rh powder, Pd powder, Os powder, Ir powder, and Pt powder are not less than 99.5%.
[0022] For the above method for preparing nano-cemented carbide, preferably, in step (2), the temperature for hydrogen dewaxing is 300 °C to 450 °C; the sintering is high-temperature pressure sintering, and the process of high-temperature pressure sintering is: heat up to 1400 °C to 1600 °C under vacuum conditions, hold for 20 min to 60 min, and then introduce 50 bar to 80 bar of high-pressure argon gas and hold for 20 min to 60 min.
[0023] Compared with the prior art, the advantages of the present invention are:
[0024] (1) The nano-cermet of the present invention adopts a new binder phase component design, which limits the components and content of the binder phase, enables a higher content of W atoms to be dissolved in the binder phase, reduces the carbon content in the binder phase, and effectively inhibits the growth of WC grains. Without adding any grain inhibitors, the growth of nano-WC grains in the cermet is effectively controlled, so that the nano-hard phase (WC grains) of the cermet maintains a "milled state", solving the problem of grain growth (including abnormal growth) of the nano-hard phase grains. The hard phase in the nano-cermet of the present invention is a nano-hard phase, that is, a cermet with nano-sized grains. The nano-hard phase grains have strong fine grain strengthening and defect passivation effects, which can improve the hardness and strength of the cermet. Compared with the existing conventional cermets with inhibitors such as Cr3C2 / VC, the nano-cermet of the present invention has better comprehensive mechanical properties, and its organizational structure is uniform and the density is high.
[0025] (2) The mixing entropy △S of all components in the binder phase of the nano-cermet of the present invention mix ≥1.51R. Since the components of the binder phase are strictly limited in the present invention, liquid phase sintering is achieved during high-temperature pressure sintering, forming a high-entropy binder phase, effectively solving the pore defects of the nano-cermet and obtaining a high-density cermet. The high-entropy binder phase has a strong diffusion retardation effect, which can effectively hinder the movement of W and C atoms and play a strong restrictive role in the dissolution, precipitation and growth of WC grain size. Since more W atoms are dissolved in the binder phase, the entropy value of the binder phase alloy is further increased. The cobalt in the binder phase of the existing WC-Co cermet has low hardness and poor high-temperature performance. Due to the high-entropy characteristics of the present invention, the binder phase has good wear resistance and high-temperature performance. It can be seen that the high-entropy binder phase and nano-WC grains of the present invention synergistically strengthen the organizational structure of the cermet, making the nano-cermet of the present invention have better comprehensive mechanics.
[0026] (3) The nano-cermet of the present invention is prepared by powder metallurgy method. The preparation process does not require adding grain inhibitors, has a simple process, low cost, good effect, and is suitable for large-scale industrial production. Description of the Drawings
[0027] Figure 1 It is a scanning electron microscope photograph of the nano-cermet of Example 1 of the present invention. Detailed Embodiments
[0028] The present invention will be further described below in conjunction with the drawings of the specification and specific preferred embodiments, but the protection scope of the present invention is not limited thereby. The materials and instruments used in the following embodiments are all commercially available.
[0029] Example 1
[0030] A nano-cemented carbide of the present invention comprises a binder phase and a nano-hard phase. The mass fraction of the binder phase is 14.62% (volume fraction is 16.89%), and the rest is the nano-hard phase, that is, the mass fraction of the nano-hard phase is 85.38%. The components of the binder phase include a first component, a second component, and a W component. The first component is Co and Ni, and the second component is Re, Ru, and Os;
[0031] The components of the binder phase satisfy the condition: X = 0.41,
[0032] X = [(a Cr + a Re + a Ru + a Rh + a Pd + a Os + a Ir + a Pt ) / n] / [(a Co + a Ni + a Fe ) / m] Formula (1)
[0033] where a Cr , a Re , a Ru , a Rh , a Pd , a Os , a Ir , a Pt are the atomic percentages of Cr, Re, Ru, Rh, Pd, Os, Ir, and Pt in all components of the binder phase respectively, a Re , a Ru , a Os are 8.9%, 12.7%, and 12.9% respectively, a Cr , a Rh , a Pd , a Ir , a Pt are all 0, n is the number of components of the second component, which is 3, a Co , a Ni , a Fe are the atomic percentages of Co, Ni, and Fe in all components of the binder phase respectively, a Co , a Ni are 28.6% and 27.7% respectively, a Fe is 0, m is the number of components of the first component, which is 2, a w is the atomic percentage of the W component in all components of the binder phase, a w is 9.2%.
[0034] In this embodiment, the mixing entropy of all components of the binder phase satisfies the condition: mixing entropy ΔS mix= 1.67R, where R is the molar gas constant, R = 8.31 J·K -1 ·mol -1 ,
[0035]
[0036] In Equation (2), N is the total number of atoms of all components in the binder phase, n1 to n r are the number of atoms of each component (each element) in the binder phase, r is the number of all components (all elements) in the binder phase, r is 5 in this embodiment, k is the Boltzmann constant, k = 1.38054×10 -23 J / K.
[0037] In this embodiment, the nano hard phase is the WC phase, and the average grain size of the WC phase is 0.18 μm.
[0038] A preparation method of the nano cemented carbide of this embodiment includes the following steps:
[0039] (1) Prepare the raw material WC powder, the first raw material powder and the second raw material powder according to Table 1. The first raw material powder is Co powder and Ni powder, and the second raw material powder is Re powder, Ru powder and Os powder. Add 15 kg of ball milling rods to the wet mill, then add the WC powder and pre-ball mill for 45 h. The Fsss particle size of the pre-ball milled WC powder is 0.15 μm. Then add the first raw material powder and the second raw material powder, add 25 g of PEG4000 and 5 g of PEG600 molding agents, and ball mill for 30 h. The ball milling medium is anhydrous alcohol, and a mixed material is obtained after ball milling.
[0040] Table 1 Raw material characteristic table of Example 1
[0041] Raw material name Fsss particle size / μm Mass / g Purity / % Co powder 0.4 27.9 99.98 Ni powder 0.4 27.9 99.85 Re powder 0.7 35.3 99.95 Ru powder 0.8 19.2 99.90 Os powder 0.9 36.1 99.72 WC powder 0.35 853.6 99.93
[0042] (2) Spray dry and granulate the mixed material, then press it into shape. First, heat it to 350 °C for hydrogen dewaxing, and then perform high-temperature pressure sintering, that is, heat it to 1460 °C under vacuum conditions, hold for 30 min, then introduce 60 bar high-pressure argon gas, hold for 40 min, and cool to room temperature to obtain the nano cemented carbide. The scanning electron microscope photograph of the nano cemented carbide is as Figure 1 shown. It can be seen from the figure that the microstructure of the nano cemented carbide is uniform, the WC grain size does not grow abnormally, and the average grain size of the WC phase is 0.18 μm. The performance of the nano cemented carbide is shown in Table 4.
[0043] Example 2
[0044] A nano-cemented carbide of the present invention includes a binder phase and a nano-hard phase. The mass fraction of the binder phase is 11.97% (volume fraction is 16.89%), and the rest is 88.03% of the nano-hard phase. The components of the binder phase include a first component, a second component, and a W component. The first component is Co, Ni, and Fe, and the second component is Cr, Re, and Ru;
[0045] The components of the binder phase satisfy the condition: X = 0.44,
[0046] X = [(a Cr + a Re + a Ru + a Rh + a Pd + a Os + a Ir + a Pt ) / n] / [(a Co + a Ni + a Fe ) / m] Formula (1)
[0047] where a Cr , a Re , a Ru , a Rh , a Pd , a Os , a Ir , a Pt are the atomic percentages of Cr, Re, Ru, Rh, Pd, Os, Ir, and Pt in all components of the binder phase, respectively. a Cr , a Re , a Ru are 8.5%, 7.8%, and 11.3% respectively. a Rh , a Pd , a Os , a Ir , a Pt are all 0. n is the number of components of the second component, which is 3. a Co , a Ni , a Fe are the atomic percentages of Co, Ni, and Fe in all components of the binder phase, respectively. a Co , a Ni , a Fe are 21.5%, 20.9%, and 20.1% respectively. m is the number of components of the first component, which is 3. a w is the atomic percentage of the W component in all components of the binder phase, and a w is 9.9%.
[0048] In this embodiment, the mixing entropy of all components of the binder phase satisfies the condition: mixing entropy △S mix= 1.86R, where R is the molar gas constant, R = 8.31 J·K -1 ·mol -1 ,
[0049]
[0050] In formula (2), N is the total number of atoms of all components in the binder phase, n1 to n r are the number of atoms of each component (each element) in the binder phase respectively, r is the number of all components in the binder phase, r is 6 in this embodiment, k is the Boltzmann constant, k = 1.38054×10 -23 J / K.
[0051] In this embodiment, the nano hard phase is the WC phase, and the average grain size of the WC phase is 0.17 μm.
[0052] A preparation method of the nano cemented carbide of this embodiment includes the following steps:
[0053] (1) Prepare raw material WC powder, the first raw material powder and the second raw material powder according to Table 2. The first raw material powder is Co powder, Ni powder and Fe powder, and the second raw material powder is Cr powder, Re powder and Ru powder. Add 15 kg of ball milling rods into the wet mill, then add WC powder for pre-ball milling for 45 h. The Fsss particle size of the WC powder after pre-ball milling is 0.15 μm. Then add the first raw material powder and the second raw material powder, add 25 g of PEG4000 and 5 g of PEG600 molding agents, and ball mill for 35 h. The ball milling medium is anhydrous alcohol to obtain a mixed material.
[0054] Table 2 Raw material characteristic table of Example 2
[0055]
[0056]
[0057] (2) Spray dry and granulate the mixed material, then press it into shape. First, heat it to 350 °C for hydrogen dewaxing, and then carry out high-temperature pressure sintering, that is, heat it to 1480 °C under vacuum, keep it warm for 30 min, then introduce 60 bar high-pressure argon gas, keep it warm for 30 min, and cool it to room temperature to obtain the nano cemented carbide. The performance of this nano cemented carbide is shown in Table 4.
[0058] Comparative Example 1
[0059] A cemented carbide, which includes a binder phase and a hard phase. The mass fraction of the binder phase is 10.05% (volume fraction 16.89%), and the rest is the hard phase. The difference is that the components of the binder phase are Co, Cr and V.
[0060] The preparation method of this cemented carbide is basically the same as that of Example 1, except that: 897.5 g of WC powder, 90.0 g of Co powder, 7.0 g of Cr3C2 powder, and 5.5 g of VC powder. The properties of this cemented carbide are shown in Table 4.
[0061] Comparative Example 2
[0062] A cemented carbide includes a binder phase and a hard phase. The mass fraction of the binder phase is 14.32% (volume fraction 16.89%), and the rest is the hard phase. The components of the binder phase include a first component, a second component, and a W component. The first component is Co and Ni, the second component is Re, Ru, and Os, and the components of the binder phase are calculated according to Equation (1) to obtain X = 0.36, a Re 、a Ru 、a Os are 8.0%, 11.5%, and 12.1% respectively, a Co 、a Ni are 29.8% and 29.2% respectively, a w is 9.4%. According to Equation (2), the mixing entropy △S of all components of the binder phase is calculated mix = 1.65R.
[0063] The preparation method of this cemented carbide is basically the same as that of Example 1, except that: the raw material characteristics in step (1) are shown in Table 3. The properties of this cemented carbide are shown in Table 4.
[0064] Table 3 Raw material characteristics table of Comparative Example 2
[0065] Raw material name Fsss / μm Mass / g Purity / % Co powder 0.4 29.6 99.98 Ni powder 0.4 29.6 99.85 Re powder 0.7 32.8 99.95 Ru powder 0.8 17.8 99.90 Os powder 0.9 33.5 99.72 WC powder 0.35 856.7 99.93
[0066] Table 4 is the performance data table of the nano-cemented carbide of Examples 1-2 and the cemented carbide of Comparative Examples 1-2. Under the same preparation process conditions, compared with Comparative Examples 1 and 2, the average WC grain size of the nano-cemented carbide of the present invention is less than 0.2 μm, and it has high density, uniform microstructure, and better comprehensive mechanical properties. The manufacturing process of the present invention is mature, the manufacturing cost is low, and it is suitable for large-scale industrial production.
[0067] Table 4 Performance data table of the cemented carbide of Examples 1-2 and Comparative Examples 1-2
[0068]
[0069]
[0070] The above are only the preferred embodiments of the present invention, and do not impose any form of limitation on the present invention. Although the present invention has been disclosed above with the preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make many possible changes and modifications to the technical solution of the present invention by using the methods and technical contents disclosed above, or modify it into equivalent embodiments with equivalent changes. Therefore, any simple modification, equivalent replacement, equivalent change and modification made to the above embodiments based on the technical essence of the present invention without departing from the technical solution of the present invention still fall within the scope of protection of the technical solution of the present invention.
Claims
1. A nano cemented carbide, characterized in that: The invention comprises a binder phase and a nano-hard phase, wherein the mass fraction of the binder phase is 8% to 18%, and the rest is the nano-hard phase, and the components of the binder phase include a first component, a second component and a W component, wherein the first component is at least one component selected from Co, Ni and Fe, and the second component is at least two components selected from Cr, Re, Ru, Rh, Pd, Os, Ir and Pt, and the total number of components of the first component and the second component is at least 5; The components of the binder phase meet the conditions: X≥0.40, X = [(a Cr + a Re + a Ru + a Rh + a Pd + a Os + a Ir + a Pt ) / n] / [(a Co + a Ni + a Fe ) / m] Equation (1) In formula (1), a Cr 、a Re 、a Ru 、a Rh 、a Pd 、a Os 、a Ir 、a Pt are the atomic percentages of Cr, Re, Ru, Rh, Pd, Os, Ir, and Pt in all components of the binder phase, n is the number of components of the second component, a Co 、a Ni 、a Fe The atomic percentages of Co, Ni and Fe in all components of the bonding phase are respectively, m is the number of components of the first component, and the atomic percentages of each component in the first component and each component in the second component in all components of the bonding phase are 5% to 35%, a w is the atomic percentage of the W component in all components of the binder phase, a w The value range is 5% to 35%.
2. The nano-hard alloy according to claim 1, characterized in that: 0.40≤X≤1.50。 3. The nano-hard alloy according to claim 1, characterized in that: a w The value range is 7% to 15%.
4. The nano-hard alloy according to claim 1, characterized in that: The mixing entropy of all components of the binder phase satisfies the condition: mixing entropy △S mix ≥1.51R, R is the gas molar constant, In formula (2), N is the total number of atoms of all components of the binder phase, n1 to n r are the number of atoms of each component in the bonding phase, r is the number of all components in the bonding phase, and k is the Boltzmann constant.
5. The nano-hard alloy according to claim 4, characterized in that: Mixing entropy △S mix ≥1.61R.
6. The nano-hard alloy according to any one of claims 1 to 5, characterized in that: The nano hard phase is a WC phase, and the average grain size of the WC phase is less than 0.2 μm.
7. A method for preparing nano-hard alloy according to any one of claims 1 to 6, characterized in that: The following steps are involved: (1) preparing WC powder, a first raw material powder and a second raw material powder, wherein the first raw material powder is at least one of Co powder, Ni powder and Fe powder, and the second raw material powder is at least two of Cr3C2 powder, Re powder, Ru powder, Rh powder, Pd powder, Os powder, Ir powder and Pt powder, and the total number of raw materials of the first raw material powder and the second raw material powder is at least 5, firstly pre-milling the WC powder, and then adding the first raw material powder and the second raw material powder and milling and mixing them evenly to obtain a mixed material; (2) Drying and granulating the mixed material, and then pressing and molding it, and then hydrogen dewaxing, sintering, and cooling it to obtain nano cemented carbide.
8. The method for preparing nano-hard alloy according to claim 7, characterized in that: In step (1), the Fsss particle size of the Co powder, Ni powder and Fe powder is ≤0.5μm, the Fsss particle size of the Cr3C2 powder, Re powder, Ru powder, Rh powder, Pd powder, Os powder, Ir powder and Pt powder is ≤1μm, the Fsss particle size of the WC powder is ≤0.4μm, and after the WC powder is pre-milled, the Fsss particle size of the pre-milled WC powder is <0.2μm, and the Fsss particle size of the pre-milled WC powder is <the Fsss particle size of the WC powder.
9. The method for preparing nano-hard alloy according to claim 7, characterized in that: In step (1), the pre-ball milling time is 30 h to 80 h, and the ball milling time is 20 h to 50 h.
10. The method for preparing nano-hard alloy according to any one of claims 7 to 9, characterized in that: In step (1), the purity of the WC powder is not less than 99.9%, and the purity of the Co powder, Ni powder, Fe powder, Cr3C2 powder, Re powder, Ru powder, Rh powder, Pd powder, Os powder, Ir powder and Pt powder is not less than 99.5%.
11. The method for preparing nano-hard alloy according to any one of claims 7 to 9, characterized in that: In step (2), the temperature of the hydrogen dewaxing is 300°C to 450°C; the sintering is high-temperature pressure sintering, and the process of the high-temperature pressure sintering is: heating to 1400°C to 1600°C under vacuum conditions, keeping warm for 20min to 60min, then introducing 50bar to 80bar high-pressure argon gas, and keeping warm for 20min to 60min.