Ternary boride metal ceramic and preparation method thereof

Abstract

The invention belongs to the technical field of metal ceramic, and particularly relates to a ternary boride metal ceramic and a preparation method thereof.The ternary boride metal ceramic comprises 90-95 wt% of a principal crystalline phase and 5-10 wt% of a binding phase, the principal crystalline phase is (Mo, W) 2 (Fe, Co and Ni) B2, the A site of the principal crystalline phase is composed of Mo and W elements, the B site of the principal crystalline phase is composed of Fe, Co and Ni elements, a stable single-phase solid solution is jointly formed, and the binding phase is a single-phase solid solution. The binding phase comprises at least one of elements Fe, Ni and Co. The preparation method comprises the steps of ball milling, drying, sintering and the like. The ternary boride metal ceramic prepared by the invention has excellent hardness, toughness, wear resistance and thermal stability, so that the ternary boride metal ceramic has longer service life and can meet more harsh service conditions.

Description

Technical Field

[0001] This invention belongs to the field of metal ceramic preparation technology, specifically relating to a ternary boride metal ceramic and its preparation method. Background Technology

[0002] Due to its high hardness and strength, cemented carbide is widely used as a cutting tool material for machining steel, stainless steel, heat-resistant alloys, cast iron, and other difficult-to-machine materials, making it the most widely used cermet today. However, traditional WC-Co cemented carbide also suffers from insufficient oxidation resistance and high-temperature strength (tungsten carbide oxidizes at temperatures above 600°C), as well as brittleness and reliability issues under certain severe working conditions.

[0003] To overcome these limitations, researchers are dedicated to developing wear-resistant materials that combine hardness, toughness, and chemical stability. Ternary boride-based cermets, with their excellent mechanical properties, good high-temperature resistance, and wear and corrosion resistance, have attracted attention in machining, cutting tool manufacturing, and parts manufacturing. Among the most studied and representative ternary boride cermets are Mo₂FeB₂, Mo₂NiB₂, and W₂CoB₂. Extensive research has shown that Mo₂FeB₂ can achieve good metallurgical bonding with steel materials, exhibiting high interfacial bonding strength and excellent wear resistance, while Mo₂NiB₂ and W₂CoB₂ cermets possess high hardness, high-temperature stability, and excellent wear and corrosion resistance.

[0004] However, existing ternary boride cermets have certain limitations under some harsh service conditions, exhibiting a relatively short service life, and their hardness, toughness, and wear resistance still need further improvement. Therefore, those skilled in the art urgently need to develop a novel ternary boride cermet and its preparation method. Summary of the Invention

[0005] The purpose of this invention is to provide a ternary boride cermet and its preparation method, so as to improve the hardness, toughness and wear resistance of the ternary boride cermet, thereby extending its service life under some harsh service conditions.

[0006] Based on one of the above-mentioned objectives, the present invention provides the following technical solution:

[0007] A ternary boride cermet contains 90-95 wt% of a main crystalline phase and 5-10 wt% of a bonding phase. The main crystalline phase is (Mo,W)₂(Fe,Co,Ni)B₂, wherein the A-site is composed of Mo and W elements, and the B-site is composed of Fe, Co, and Ni elements, which together form a stable single-phase solid solution. The bonding phase contains at least one element, Fe, Ni, or Co. In addition, the bonding phase may also contain an intermetallic phase. The grain size of the ternary boride cermet is 1-2 μm.

[0008] Preferably, the raw materials for preparing the ternary boride cermet include, by mass percentage: 20-30 wt% Mo2FeB2 powder, 20-40 wt% Mo2NiB2 powder, and 40-60 wt% W2CoB2 powder.

[0009] Preferably, the raw materials for preparing Mo2FeB2 include, by mass percentage: 20.7 wt% iron, 71.1 wt% molybdenum, and 8.2 wt% boron.

[0010] Preferably, the raw materials for preparing Mo2NiB2 include, by mass percentage: 21.53 wt% iron, 70.4 wt% molybdenum, and 9.07 wt% boron.

[0011] Preferably, the raw materials for preparing W2CoB2 include, by mass percentage: 73wt% tungsten, 20.67wt% cobalt, and 6.33wt% boron.

[0012] Preferably, the particle size of the Mo2FeB2 powder, Mo2NiB2 powder, and W2CoB2 powder is 1~3μm.

[0013] Based on the second objective mentioned above, this invention also proposes a preparation process for ternary boride metal ceramics, comprising the following steps: S1. Prepare and mix the raw materials Mo2FeB2, Mo2NiB2, and W2CoB2 according to their respective mass percentages to obtain the corresponding mixtures. Then, place each of the corresponding mixtures into a roller ball mill and wet-mill for 12-24 hours. The rotation speed of the roller ball mill is 90 r / min, the wet milling medium is anhydrous ethanol, and the grinding balls are ZrO2 balls. The mass ratio of the grinding balls, the corresponding mixtures, and anhydrous ethanol in the roller ball mill is 3:1:1.2. S2. After ball milling, the corresponding mixtures were dried in a vacuum drying oven at 70°C for 6 hours and then passed through a 200-mesh sieve to obtain the corresponding alloy powders. S3. The corresponding alloy powders were vacuum sintered at 1250-1300℃ for 30 min to obtain Mo2FeB2 powder, Mo2NiB2 powder and W2CoB2 powder respectively. S4. The Mo2FeB2 powder, Mo2NiB2 powder and W2CoB2 powder obtained in S3 are mixed according to the mass percentage of the raw materials for preparing ternary boride metal ceramics and filled into a graphite mold for hot pressing sintering. The hot pressing sintering temperature is 1400-1500℃, the pressure is 30-45MPa, and the sintering time is 30min to obtain the ternary boride metal ceramic.

[0014] Preferably, the ternary boride cermet prepared in step S4 consists of a (Mo,W)₂(Fe,Co,Ni)B₂ hard phase and a Fe-Co-Ni bonding phase. The (Mo,W)₂(Fe,Co,Ni)B₂ exhibits a crystal structure similar to W₂CoB₂. These ternary borides possess extremely strong BB covalent bonds, giving them excellent hardness, wear resistance, and thermal stability. Furthermore, the Fe-Co-Ni bonding phase exhibits higher hardness and better stability compared to pure Co or Fe bonding phases, effectively improving the impact resistance of the ceramic material while enhancing its hardness.

[0015] Compared with the prior art, the present invention has the following beneficial effects: The ternary boride cermet prepared by this invention possesses excellent hardness, toughness, wear resistance, and thermal stability. It is also resistant to oxidation, has a long service life, and can meet more demanding service conditions. Its hardness can reach 1680~1860 Hv, its flexural strength can reach 986~1150 MPa, and its fracture toughness can reach 8.7~9.6 MPa·m. 1 / 2 The coefficient of friction can reach 0.21~0.32. Attached Figure Description

[0016] Figure 1 This is a SEM image of the ternary boride cermet in Example 1 of the present invention. Detailed Implementation

[0017] This invention provides a ternary boride cermet containing 90-95 wt% of a main crystalline phase and 5-10 wt% of a bonding phase. The main crystalline phase is (Mo,W)₂(Fe,Co,Ni)B₂, wherein the A-site is composed of Mo and W elements, and the B-site is composed of Fe, Co, and Ni elements, which together form a stable single-phase solid solution. The bonding phase contains at least one element, Fe, Ni, or Co. In addition, the bonding phase may also contain an intermetallic phase. The grain size of the ternary boride cermet is 1-2 μm.

[0018] Specifically, the raw materials for preparing the ternary boride cermet include Mo2FeB2 powder, Mo2NiB2 powder, and W2CoB2 powder. The particle size of the Mo2FeB2 powder, Mo2NiB2 powder, and W2CoB2 powder is 1~3μm.

[0019] The following detailed explanation of the invention patent solution, using specific examples, illustrates the invention patent in detail.

[0020] Example 1 The ternary boride cermet provided in this embodiment comprises the following raw materials by mass percentage: 27.2 wt% Mo2FeB2 powder; 27.5 wt% Mo2NiB2 powder; and 45.3 wt% W2CoB2 powder.

[0021] The raw materials for preparing Mo2FeB2, by mass percentage, include: 20.7 wt% iron, 71.1 wt% molybdenum, and 8.2 wt% boron; the raw materials for preparing Mo2NiB2, by mass percentage, include: 21.53 wt% iron, 70.4 wt% molybdenum, and 9.07 wt% boron; and the raw materials for preparing W2CoB2, by mass percentage, include: 73 wt% tungsten, 20.67 wt% cobalt, and 6.33 wt% boron.

[0022] This embodiment also proposes a method for preparing the above-mentioned ternary boride metal ceramics, including the following steps: S1. Prepare and mix the raw materials Mo2FeB2, Mo2NiB2, and W2CoB2 according to their respective mass percentages to obtain corresponding mixtures. Then, place each mixture into a roller ball mill and wet-mill for 12 hours. The rotation speed of the roller ball mill is 90 r / min, the wet milling medium is anhydrous ethanol, and the grinding balls are ZrO2 balls. The mass ratio of the grinding balls, the corresponding mixture, and anhydrous ethanol in the roller ball mill is 3:1:1.2. S2. After ball milling, the corresponding mixtures were dried in a vacuum drying oven at 70°C for 6 hours and then passed through a 200-mesh sieve to obtain the corresponding alloy powders. S3. The corresponding alloy powders were vacuum sintered at 1250℃ for 30 min to obtain Mo2FeB2 powder, Mo2NiB2 powder and W2CoB2 powder respectively. S4. The Mo2FeB2 powder, Mo2NiB2 powder and W2CoB2 powder obtained in S3 are mixed according to the mass percentage of the raw materials for preparing ternary boride metal ceramics and filled into a graphite mold for hot pressing sintering. The hot pressing sintering temperature is 1450℃, the pressure is 45MPa and the sintering time is 30min to obtain the ternary boride metal ceramic.

[0023] Figure 1 The image shows a SEM image of the ternary boride cermet prepared in this embodiment.

[0024] Example 2 The only difference between this embodiment and Embodiment 1 is that the ternary boride cermet provided in this embodiment, by mass percentage, includes the following raw materials: 20wt% Mo2FeB2 powder; 40wt% Mo2NiB2 powder; and 40wt% W2CoB2 powder.

[0025] In step S1, wet milling is performed for 24 hours; in step S4, the hot pressing sintering temperature is 1500℃.

[0026] Example 3 The only difference between this embodiment and Embodiment 1 is that the ternary boride cermet provided in this embodiment, by mass percentage, includes the following raw materials: 30wt% Mo2FeB2 powder; 20wt% Mo2NiB2 powder; and 50wt% W2CoB2 powder.

[0027] In step S3, the vacuum sintering temperature is 1300℃; in step S4, the hot pressing sintering temperature is 1500℃ and the pressure is 30MPa.

[0028] Example 4 The only difference between this embodiment and Embodiment 1 is that the ternary boride cermet provided in this embodiment, by mass percentage, includes the following raw materials: 20wt% Mo2FeB2 powder; 20wt% Mo2NiB2 powder; and 60wt% W2CoB2 powder.

[0029] The hot pressing sintering temperature in step S4 is 1400℃.

[0030] Example 5 The only difference between this embodiment and Embodiment 1 is that the ternary boride cermet provided in this embodiment, by mass percentage, includes the following raw materials: 25wt% Mo2FeB2 powder; 40wt% Mo2NiB2 powder; and 35wt% W2CoB2 powder.

[0031] In step S1, wet milling is performed for 20 hours; in step S3, the vacuum sintering temperature is 1300℃; and in step S4, the pressure is 30MPa.

[0032] Example 6 The only difference between this embodiment and Embodiment 1 is that the ternary boride cermet provided in this embodiment, by mass percentage, includes the following raw materials: 30wt% Mo2FeB2 powder; 30wt% Mo2NiB2 powder; and 40wt% W2CoB2 powder.

[0033] In step S3, the temperature of vacuum sintering is 1300℃; in step S4, the temperature of hot pressing sintering is 1400℃.

[0034] Comparative Example 1 This comparative example provides a ternary boride composite ceramic and its preparation process. The only difference from Example 1 is that the ternary boride metal ceramic provided in this comparative example, by mass percentage, includes the following raw materials: 90 wt% Mo2FeB2 powder; 5 wt% Mo2NiB2 powder; and 5 wt% W2CoB2 powder.

[0035] In step S3, the temperature of vacuum sintering is 1300℃; in step S4, the temperature of hot pressing sintering is 1500℃.

[0036] Comparative Example 2 The only difference between this comparative example and Example 1 is that the ternary boride cermet provided in this comparative example, by mass percentage, includes the following raw materials: 5 wt% Mo2FeB2 powder; 85 wt% Mo2NiB2 powder; and 10 wt% W2CoB2 powder.

[0037] In step S3, the hot pressing sintering temperature in step S4 is 1400℃.

[0038] Performance Characterization The ternary boride cermets prepared in Examples 1-6 and Comparative Examples 1-2 were tested, and the test results are shown in Table 1: Table 1. Performance parameters of ternary boride cermets prepared in Examples 1-6 and Comparative Examples 1-2

[0039] As can be seen from the above examples and comparative examples, by introducing the (Mo,W)₂(Fe,Co,Ni)B₂ hard phase and the Fe-Co-Ni bonded phase, the (Mo,W)₂(Fe,Co,Ni)B₂ exhibits a crystal structure similar to W₂CoB₂ and possesses extremely strong BB covalent bonds, giving it excellent hardness, wear resistance, and thermal stability. Furthermore, the Fe-Co-Ni bonded phase has higher hardness and better stability than the pure Co or Fe bonded phases, effectively improving the impact resistance of ceramic materials while enhancing material hardness.

[0040] The ternary boride cermets prepared in the above embodiments of the present invention all possess excellent hardness, toughness, wear resistance, and thermal stability, and are not easily oxidized, resulting in a long service life and the ability to meet more demanding service conditions. Their hardness can reach 1680~1860 Hv, their flexural strength can reach 986~1150 MPa, and their fracture toughness can reach 8.7~9.6 MPa·m. 1 / 2 The friction coefficient can reach 0.21~0.32, and its hardness, bending strength and fracture toughness are all better than those of the comparative example, thus achieving significant technological progress.

[0041] Although the above embodiments have provided a detailed description of the present invention, they are only some embodiments of the present invention, and not all embodiments. Other embodiments can be obtained based on these embodiments without creative effort, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A ternary boride cermet, characterized in that, It contains 90-95 wt% of a main crystalline phase and 5-10 wt% of a bonding phase, wherein the main crystalline phase is (Mo,W)2(Fe,Co,Ni)B2 and the bonding phase contains at least one of the elements Fe, Ni, and Co.

2. The ternary boride cermet according to claim 1, characterized in that, The bonding phase includes an intermetallic phase.

3. The ternary boride metal ceramic according to claim 1, characterized in that, The grain size of the ternary boride cermet is 1~2μm.

4. A ternary boride cermet according to any one of claims 1-3, characterized in that, The raw materials for preparing the ternary boride cermet, by mass percentage, include: 20-30 wt% Mo2FeB2 powder, 20-40 wt% Mo2NiB2 powder, and 40-60 wt% W2CoB2 powder.

5. The ternary boride metal ceramic according to claim 4, characterized in that, The raw materials for preparing Mo2FeB2, by mass percentage, include: 20.7 wt% iron, 71.1 wt% molybdenum, and 8.2 wt% boron.

6. The ternary boride cermet according to claim 5, characterized in that, The raw materials for preparing Mo2NiB2, by mass percentage, include: 21.53 wt% iron, 70.4 wt% molybdenum, and 9.07 wt% boron.

7. A ternary boride metal ceramic according to claim 6, characterized in that, The raw materials for preparing W2CoB2, by mass percentage, include: 73 wt% tungsten, 20.67 wt% cobalt, and 6.33 wt% boron.

8. A ternary boride metal ceramic according to claim 7, characterized in that, The particle size of the Mo2FeB2 powder, Mo2NiB2 powder, and W2CoB2 powder is 1~3μm.

9. A preparation process for a ternary boride cermet based on claim 4 or 8, characterized in that, Includes the following steps: S1. Prepare and mix the raw materials Mo2FeB2, Mo2NiB2, and W2CoB2 according to their respective mass percentages to obtain the corresponding mixtures. Then, place each of the corresponding mixtures into a roller ball mill and wet-mill for 12-24 hours. The rotation speed of the roller ball mill is 90 r / min, the wet milling medium is anhydrous ethanol, and the grinding balls are ZrO2 balls. The mass ratio of the grinding balls, the corresponding mixtures, and anhydrous ethanol in the roller ball mill is 3:1:1.

2. S2. After ball milling, the corresponding mixtures were dried in a vacuum drying oven at 70°C for 6 hours and then passed through a 200-mesh sieve to obtain the corresponding alloy powders. S3. The corresponding alloy powders were vacuum sintered at 1250-1300℃ for 30 min to obtain Mo2FeB2 powder, Mo2NiB2 powder and W2CoB2 powder respectively. S4. The Mo2FeB2 powder, Mo2NiB2 powder and W2CoB2 powder obtained in S3 are mixed according to the mass percentage of the raw materials for preparing ternary boride metal ceramics and filled into a graphite mold for hot pressing sintering. The hot pressing sintering temperature is 1400-1500℃, the pressure is 30-45MPa, and the sintering time is 30min to obtain the ternary boride metal ceramic.

10. The preparation process according to claim 9, characterized in that, The ternary boride cermet prepared in step S4 consists of a (Mo,W)2(Fe,Co,Ni)B2 hard phase and a Fe-Co-Ni bonded phase, wherein (Mo,W)2(Fe,Co,Ni)B2 exhibits a crystal structure similar to W2CoB2.

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