A multi-scale honeycomb structure Ti(C,N)-based cermet and its preparation method

Abstract

This invention discloses a multi-scale honeycomb structure Ti(C,N)-based cermet and its preparation method. The cermet has the following composition (mass fraction): Ti: 50.56~53.92, W: 1.96~2.04, Ta: 1.48~1.52, Nb: 1.87~1.93, Mo: 7.51~8.18, Ni: 11.91~16.23, C: 12.61~14.29, N: 6.93~7.06. The preparation method includes the following steps: (1) using Ti(C,N) as the base metal. (1) Using C,N), WC, TaC, NbC, Mo2C, Ni and graphite powder as raw materials, the mixture is prepared and ball-milled; (2) The mixed slurry is poured into a bubbling fluidized bed for fluidized drying to obtain mixed powder; (3) The mixed powder is pressed and sintered under vacuum to obtain multi-scale honeycomb structure Ti(C,N) based metal ceramic, which has good comprehensive mechanical properties; This method achieves multi-scale distribution of fine crystal agglomerates in the mixture by adjusting the drying process, and has the characteristics of low cost, simple process and easy industrialization.

Description

Technical Field

[0001] This invention belongs to the field of powder metallurgy technology, specifically relating to a multi-scale honeycomb structure Ti(C,N)-based cermet and its preparation method. Background Technology

[0002] Ti(C,N)-based cermets are increasingly being used in cutting tools, mold materials, and high-temperature wear-resistant parts due to their high hardness, excellent chemical stability, wear resistance, and high-temperature oxidation resistance. Compared with traditional WC-Co cemented carbides, cermets have lower production costs and superior performance. When used as tool materials for dry and continuous cutting, they offer better service life and cutting efficiency than cemented carbide tools. Therefore, Ti(C,N)-based cermets can be considered an ideal alternative to cemented carbide, well-suited to the high-speed, precision, and intelligent development trends of modern machining.

[0003] Currently, the main problem with Ti(C,N)-based cermets is their relatively low strength and toughness, making it difficult for them to meet the requirements of complex working conditions and limiting their development in other application fields. Some researchers have studied the strengthening and toughening of cermets from various aspects, such as interface purification, process optimization, and the addition of nanophases. Although these methods can improve the overall mechanical properties of cermets to some extent, the addition of nanoparticles and other additives is difficult to disperse in the mixture during actual production, resulting in uneven final products. Process optimization involves the development and use of new preparation equipment, which also increases production costs, preventing large-scale application in the industrial field. Meanwhile, some researchers have developed mixed-crystal structure cermets with both coarse and fine hard phase grains, which can improve their hardness and toughness to some extent. However, some fine particles preferentially dissolve during liquid-phase sintering and precipitate on the surface of coarse particles, causing the coarse hard phase to grow, making it difficult to obtain mixed-crystal structure Ti(C,N)-based cermets with a bimodal distribution of coarse and fine particles. To achieve a balance between high hardness and high toughness, a network structure with a coarse-grained matrix and fine-grained agglomerates has gradually attracted researchers in the field of cemented carbide. This structure possesses the good toughness of coarse grains while exhibiting the high hardness and strength of fine grains, resulting in excellent comprehensive mechanical properties. Patent CN 106191498A discloses "a method for preparing a network structure cemented carbide," which involves spraying a suspension of a mixture containing high-cobalt coarse grains onto fine-grained mixed agglomerates to prepare a mixed-grained cemented carbide. However, compared to traditional cemented carbide production processes, this method significantly increases the raw material and time costs, has a lower matrix content, and produces a uniform agglomerate size, making it difficult to meet the diverse requirements of industrial production. Patent CN 101787479 B discloses a "network structure cemented carbide and its preparation method." This method prepares a network structure cemented carbide by granulation of low-cobalt cemented carbide agglomerates and a high-cobalt cemented carbide matrix through processes such as incorporating forming agents. This results in a network structure cemented carbide with superior comprehensive mechanical properties. However, this method involves a complex process and produces cemented carbide with relatively high porosity. In the field of cermets, patent CN 114752835 A discloses a "Ti(C,N)-based cermet with a honeycomb structure and its preparation method." This method uses two types of hard phase powders with different grain sizes and prepares the cermet microstructure through in-situ carbothermal reduction, resulting in a microstructure containing both agglomerates and a matrix. The comprehensive mechanical properties are improved compared to cermets prepared by traditional methods. However, this method also suffers from drawbacks such as cumbersome processes, high time and raw material costs. Furthermore, the boiling of the slurry in the container during oven drying makes the location and size of bubbles uncontrollable, and the final agglomerate size and distribution cannot be controlled, making it difficult to handle various working conditions in actual production.Therefore, in order to meet the various application needs in the actual production of Ti(C,N)-based cermets and expand their application scope, it is particularly important to develop a multi-scale honeycomb structure Ti(C,N)-based cermet with simple and controllable process, low cost, and controllable agglomerate size. Summary of the Invention

[0004] The purpose of this invention is to provide a multi-scale honeycomb structure Ti(C,N)-based cermet and its preparation method to solve the problems of low hardness in coarse-grained cermets and low toughness in fine-grained cermets.

[0005] This application is achieved through the following technical solution:

[0006] First, this application provides a multi-scale honeycomb structure Ti(C,N)-based cermet, which is a honeycomb microstructure composed of fine-grained agglomerates of different sizes and a coarse-grained matrix surrounding them; the fine-grained agglomerates are composed of hard phase particles with a core-ring structure, coreless hard phase particles, and a Ni-based binder phase; the coarse-grained matrix is ​​composed of hard phase particles with a core-ring structure and a Ni-based binder phase; the core component of the hard phase particles with a core-ring structure is Ti(C,N), and the ring phase component is (Ti,Mo,W,Ta,Nb)(C,N); the component of the coreless hard phase particles is (Ti,Mo,W,Ta,Nb)(C,N).

[0007] The particle size of the aforementioned fine-grained agglomerates exhibits a multi-scale distribution in the cermet, meaning that the total volume fraction of fine-grained agglomerates in the cermet ranges from 33.4% to 56.1%. These fine-grained agglomerates include large, medium, and small agglomerates. Specifically, small-scale agglomerates have a size of 20–40 μm (inclusive of 20 μm and 40 μm) and account for 1.6–5.2% of the cermet's volume fraction; medium-scale agglomerates have a size of 40–100 μm (exclusive of 40 μm but inclusive of 100 μm) and account for 15.3–24.7% of the cermet's volume fraction; and large-scale agglomerates have a size of 100–150 μm (exclusive of 100 μm but inclusive of 150 μm) and account for 16.5–26.2% of the cermet's volume fraction.

[0008] The cermet is composed of the following raw materials in the indicated mass percentages: Ti: 50.56~53.92%, W: 1.96~2.04%, Ta: 1.48~1.52%, Nb: 1.87~1.93%, Mo: 7.51~8.18%, Ni: 11.91~16.23%, C: 12.61~14.29%, N: 6.93~7.06%.

[0009] Secondly, this application also provides a method for preparing multi-scale honeycomb structure Ti(C,N)-based cermets, comprising the following steps:

[0010] (1) A mixture was prepared by using Ti(C,N) powder, WC powder, TaC powder, NbC powder, Mo2C powder, Ni powder and graphite powder with a particle size of 2~4μm as raw materials. The resulting mixed powder contained, by mass percentage: Ti: 50.56~53.92%, W: 1.96~2.04%, Ta: 1.48~1.52%, Nb: 1.87~1.93%, Mo: 7.51~8.18%, Ni: 11.91~16.23%, C: 12.61~14.29%, N: 6.93~7.06%.

[0011] (2) The mixture obtained in step (1) is placed into a ball mill jar for mixing to obtain a mixed slurry;

[0012] (3) The mixed slurry obtained in step (2) is poured into a bubbling fluidized bed equipped with a perforated plate for drying to obtain a mixed powder;

[0013] (4) The mixed powder obtained in step (3) is pressed and sintered in vacuum to obtain Ti(C,N)-based metal ceramics with multi-scale honeycomb structure.

[0014] Furthermore, in step (2), ball milling media are added for mixing; the ball milling media is preferably anhydrous ethanol; the amount of ball milling media added is preferably 1.3 to 1.5 times the weight of the mixed powder.

[0015] Furthermore, in step (3), the inlet temperature of the fluidized bed is 90~110℃, the fluidizing gas velocity is 0.5~2m / s, the fluidizing gas is air, and the bed height is 50~70mm.

[0016] Furthermore, in step (3), the porous plate of the fluidized bed is provided with nylon mesh of different mesh sizes, and the mesh with the same aperture is aggregated into a shape (such as a rectangle) and distributed alternately with other mesh sizes; wherein the 30,000 mesh nylon mesh occupies 35~45% of the area of ​​the whole plate, the 20,000 mesh nylon mesh occupies 25~35% of the area of ​​the whole plate, and the 15,000 mesh nylon mesh occupies 25~35% of the area of ​​the whole plate.

[0017] Furthermore, in step (4), the pressing pressure is 150~200MPa, and the green blank is obtained by molding through a tablet press under this pressure.

[0018] Furthermore, in step (4), vacuum sintering is divided into four stages: the first stage: heating to 800~1000℃ at 6℃ / min, holding for 1~1.5h, and maintaining a vacuum of 5~7Pa; the second stage: heating to 1260~1300℃ at 3℃ / min, holding for 2~4h, and maintaining a vacuum of 5~7Pa; the third stage: heating to 1450~1480℃ at 2℃ / min, holding for 5~10min, then cooling to 1320~1360℃ at a rate of 10℃ / min, holding for 6~8h, and maintaining a vacuum of 30~35Pa; the fourth stage: cooling to below 1100℃ at a cooling rate of 10℃ / min and then cooling with the furnace, maintaining a vacuum of 5~7Pa.

[0019] To achieve controllable particle size of fine grains, the mixed slurry is dried in a bubbling fluidized bed in step (3). During the drying process, a certain fluidizing gas velocity keeps the powder particles in the slurry in a fluidized state. The fluidizing gas in the fluidized bed appears in the slurry in the form of bubbles. The initial size of the bubbles is determined by the pore size of the nylon mesh set on the bottom plate of the bed. The bubbles generated by the gas through small holes have smaller diameters, while the bubbles generated through large holes have larger diameters. The proportion of bubbles of different sizes generated by nylon meshes with different pore sizes is also related to the proportion of the corresponding pore size distribution. During the rising process of the bubbles, the size and number of particles that are adapted to different bubble sizes are also different. That is, the surface tension of large bubbles is greater, and they adsorb more small particles, resulting in larger agglomerates. When the bubbles rise to the surface of the bed and break, the particles move downward along the wall due to gravity, forming a circulating motion in the fluidized bed. Within the slurry bed, particle collisions cause the transfer and loss of momentum and energy between particles, resulting in reduced particle velocity and pressure in some areas. Simultaneously, particles outside these areas are pushed in due to the pressure difference, and under the influence of gas-phase viscous stress, particle agglomerates gradually form. Because the raw material powder has a very fine particle size, small particles are easily adsorbed onto the bubble surface, increasing the interparticle forces, such as van der Waals forces and electrostatic forces. As the slurry gradually dries, the smaller powder particles aggregated by the bubbles eventually form fine particle agglomerates with a certain strength through various binding forces, primarily liquid bridging forces. Depending on the different bubble sizes generated by the different pore sizes of the porous plates, particle agglomerates of varying sizes form in the surrounding area. Finally, the dried powder is pressed and sintered to obtain Ti(C,N)-based cermets with a multi-scale honeycomb structure.

[0020] In addition, unlike traditional vacuum sintering, the vacuum sintering step (4) of this application is divided into four stages. In the first stage, the temperature is raised to 800~1000℃ and held, and the adsorbed oxygen on the surface of the powder is removed more thoroughly, which increases the bonding force between the binder phase and the hard phase. In the second stage, the temperature is raised to 1260~1300℃ and held, and the carbides in the mixture dissolve with each other and form an inner ring phase on the surface of the hard phase to prevent the grains from agglomerating and growing. This makes the fine grains mainly composed of coreless hard phase and core-ring hard phase. The undissolved coarse Ti(C,N) particles form a core-ring hard phase during the dissolution process. This phase acts as a matrix to wrap around the fine grains, so that the fine grains and the coarse matrix are pre-consolidated, maintaining the size and shape of the grains. In the third stage, the temperature is raised to 1450~1480℃ and held for a short time. Because fine particles have a greater sintering driving force, fine grain agglomerates shrink faster, and the sintered body reaches the critical density. At the same time, the grains do not grow significantly. Then, the temperature is lowered to 1320~1360℃ at a rate of 10℃ / min and held for a long time. At the lower temperature, grain boundary migration is suppressed, while grain boundary diffusion continues. The size of fine grains within the agglomerates remains at the submicron scale, and the densification process is finally completed. The purpose of this stage is to suppress grain growth during liquid phase sintering without affecting density, so that the cermet can maintain a multi-scale agglomerate and matrix mixed distribution. In the fourth stage, the temperature is lowered to below 1100℃ at a cooling rate of 10℃ / min, and then cooled with the furnace to prevent the agglomeration and growth of smaller hard phase particles. This can refine the grains to a certain extent, so that the cermet can maintain the characteristics of a coarse-grained matrix and fine-grained agglomerates mixed distribution.

[0021] Compared with the prior art, the beneficial effects of the present invention include:

[0022] 1. The multi-scale honeycomb structure Ti(C,N)-based cermet provided by this invention possesses excellent comprehensive mechanical properties. By adjusting the equipment and process, the multi-scale distribution of the agglomerate structure can be effectively controlled, thus preparing honeycomb structure Ti(C,N)-based cermets. In the multi-scale agglomerates, the fine grain size distribution within the large-scale agglomerates is narrower, and the dissolution and exudation process is more significantly suppressed. The hard phase grains within the agglomerates are refined, improving the hardness and strength of the cermet. Compared with cermets with a single-scale agglomerate distribution, the number of small-scale agglomerates increases at the same volume fraction, the interface between the agglomerates and the matrix increases, and the bifurcation and deflection of cracks when passing through the agglomerate interface increases, further enhancing its toughness.

[0023] 2. This invention utilizes the bubbles generated when the fluidizing gas in the fluidized bed passes through the multi-pore size of the nylon mesh, as well as the gas-solid two-phase flow, to adsorb and fluidize the fine powder particles in the mixed slurry, and to generate multi-scale particle agglomerates on the wall and inside, while other areas contain larger coarse powder particles, ultimately preparing a multi-scale honeycomb structure Ti(C,N)-based metal ceramic.

[0024] 3. The two-step sintering process of the present invention is simple, can meet production requirements, reduce production costs, and is conducive to industrialization. Attached Figure Description

[0025] Figure 1 As in Example 1, it contains component 1 # Low-magnification SEM micrograph of multi-scale honeycomb structure Ti(C,N)-based cermets;

[0026] Figure 2 As in Example 1, it contains component 1 # High-magnification SEM image of multi-scale honeycomb structure Ti(C,N)-based cermets;

[0027] Figure 3 For example 2, which contains component 2 # Low-magnification SEM micrograph of multi-scale honeycomb structure Ti(C,N)-based cermets;

[0028] Figure 4 For example 3, which contains component 3 # Low-magnification SEM micrograph of multi-scale honeycomb structure Ti(C,N)-based cermets;

[0029] Figure 5 This is a schematic diagram showing the distribution of nylon meshes with different aperture sizes used in all embodiments. Detailed Implementation

[0030] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0031] The raw materials used in the following examples are Ti(C,N) powder, WC powder, TaC powder, NbC powder, Mo2C powder, Ni powder, and graphite powder, all with a powder size of 2~4μm; all of these raw materials are commercially available.

[0032] The vacuum sintering furnace used in the example is the ZT-15-20 model sintering furnace from Chenhua Electric Furnace Company.

[0033] The fluidized bed is the Y-PZ pilot-scale fluidized bed from Yuyan Machinery Equipment Company. The nylon mesh structures with different mesh counts used in the examples are all... Figure 5 As shown, nylon meshes with different aperture sizes are connected by stainless steel pressure strips.

[0034] Table 1 shows the composition of the mixtures with the three formulations. The mixtures were prepared into cermets using three different process parameters as described in Examples 1-3, and the Rockwell hardness, flexural strength, and fracture toughness of the samples were measured at room temperature. Rockwell hardness was measured according to GB / T 3849.1-2015, room temperature flexural strength was measured according to GB / T 3851-2015, and fracture toughness was measured according to GB / T33819-2017.

[0035] The volume fraction of fine-grained agglomerates in the cermet was calculated using grayscale values ​​obtained from SEM images via ImageJ software. The end values ​​of 150 μm and 20 μm were determined by the maximum and minimum values ​​of the longest side of the agglomerates in the SEM images, respectively, while the end values ​​of 40 μm and 100 μm were determined by the overall agglomerate size distribution.

[0036] Table 1. Composition of the mixture (by mass percentage) for the three-component formulation.

[0037] Element Ti W Ta Nb Mo Ni C N <![CDATA[1 # ]]> 50.56 2.04 1.52 1.93 8.18 16.23 12.61 6.93 <![CDATA[2 # ]]> 52.76 2.01 1.50 1.51 7.83 13.88 13.52 6.99 <![CDATA[3 # ]]> 53.92 1.96 1.48 1.87 7.51 11.91 14.29 7.06

[0038] Example 1

[0039] 1. Preparation of mixed slurry: Prepare three kinds of mixtures according to the components in Table 1, add anhydrous ethanol as the ball milling medium, the amount of which is 1.3 times the weight of the mixture, and place them in a planetary ball mill for ball milling at a speed of 260 rpm for 20 hours;

[0040] 2. Fluidized Bed Drying: Pour the slurry obtained in step 1 into a bubbling fluidized bed. The inlet air temperature is 90℃, the fluidizing gas velocity is 0.5m / s, and the fluidizing gas is air. The bed height is 70mm. 30,000-mesh nylon mesh occupies 40% of the total area of ​​the bed, 20,000-mesh nylon mesh occupies 25%, and 15,000-mesh nylon mesh occupies 35%. The nylon mesh structure is as follows... Figure 5 As shown;

[0041] 3. Compression molding: The powder obtained in step 2 is molded using a tablet press with a compression pressure of 150 MPa;

[0042] 4. Vacuum sintering: This process is carried out in a vacuum sintering furnace and consists of four stages.

[0043] First stage: Heat to 800℃ at 6℃ / min, hold for 1.5h, vacuum set at 5Pa; Second stage: Heat to 1260℃ at 3℃ / min, hold for 2h, vacuum set at 5Pa; Third stage: Heat to 1460℃ at 2℃ / min, hold for 5min, then cool to 1320℃ at a cooling rate of 10℃ / min, hold for 6h, vacuum set at 30Pa; then cool to below 1100℃ at a cooling rate of 10℃ / min and cool with the furnace, vacuum set at 5Pa.

[0044] Under the above preparation process conditions, the mechanical properties of the metal ceramics prepared with different component ratios are shown in Table 2, and the volume fraction of agglomerates of the metal ceramics prepared with different component ratios are shown in Table 3.

[0045] Table 2 shows the mechanical properties of different composition cermets prepared using the process described in Example 1.

[0046] Element <![CDATA[1 # ]]> <![CDATA[2 # ]]> <![CDATA[3 # ]]> Bending strength (MPa) 2254 2136 2085 Hardness (HRA) 93.2 93.5 93.4 <![CDATA[Fracture toughness (MPa·m 1 / 2 ).]]> 9.5 9.2 9.7

[0047] Table 3 shows the volume fraction of agglomerates in the cermets prepared using the process described in Example 1.

[0048] Aggregates <![CDATA[1 # ]]> <![CDATA[2 # ]]> <![CDATA[3 # ]]> Small size (20μm≤particle size≤40μm) 1.6% 2.3% 1.9% Medium size (40μm < particle size ≤ 100μm) 16.5% 15.3% 17.1% Large size (100μm < particle size ≤ 150μm) 19.7% 17.8% 21.8%

[0049] Figure 1 The sample prepared for this embodiment has component 1 # SEM low-magnification microstructure of multi-scale honeycomb structure Ti(C,N) based cermet, showing the honeycomb microstructure composed of fine-grained cermet agglomerates and coarse-grained cermet matrix. Figure 2 For having component 1 # High-magnification SEM images of multi-scale honeycomb structure Ti(C,N)-based cermets, including: 1. Core-ring hard phase; 2. Coreless hard phase; 3. Ni-based binder phase; 4. Matrix; 5. Aggregates.

[0050] In practice, the vacuum degree in the first, second, and fourth stages of the vacuum sintering process is controlled within the range of 5 to 7 Pa, and the vacuum degree in the third stage is controlled within the range of 30 to 35 Pa, which can achieve the purpose of the invention.

[0051] Example 2

[0052] 1. Preparation of mixed slurry: Prepare three kinds of mixtures according to the components in Table 1, add anhydrous ethanol as the ball milling medium, the amount of which is 1.4 times the weight of the mixture, place it in a planetary ball mill and ball mill at a speed of 260 rpm for 20 hours;

[0053] 2. Fluidized Bed Drying: Pour the slurry obtained in step 1 into a bubbling fluidized bed. The inlet air temperature is 100℃, the fluidizing gas velocity is 1m / s, the fluidizing gas is air, the bed height is 60mm, and the area occupied by 30,000 mesh nylon mesh is 35%, 20,000 mesh nylon mesh is 35%, and 15,000 mesh nylon mesh is 30%. The nylon mesh structure is as follows: Figure 5 As shown, Figure 5 In the middle, 6-stainless steel pressure strip.

[0054] 3. Compression molding: The powder obtained in step 2 is molded using a tablet press with a compression pressure of 180 MPa;

[0055] 4. Vacuum sintering: The process is carried out in a vacuum sintering furnace. The temperature is increased to 1000℃ at a rate of 6℃ / min and held for 1 hour with a vacuum of 6Pa. Then, the temperature is increased to 1280℃ at a rate of 3℃ / min and held for 3 hours with a vacuum of 6Pa. Next, the temperature is increased to 1480℃ at a rate of 2℃ / min and held for 7 minutes. Then, the temperature is decreased to 1360℃ at a rate of 10℃ / min and held for 7 hours with a vacuum of 30Pa. Finally, the temperature is decreased to below 1100℃ at a rate of 10℃ / min and cooled with the furnace with a vacuum of 6Pa.

[0056] Under the above preparation process conditions, the mechanical properties of the metal ceramics prepared with different component ratios are shown in Table 4, and the volume fraction of agglomerates of the metal ceramics prepared with different component ratios are shown in Table 5.

[0057] Table 4 shows the mechanical properties of different composition metal ceramics prepared using the process described in Example 2.

[0058] Element <![CDATA[1 # ]]> <![CDATA[2 # ]]> <![CDATA[3 # ]]> Bending strength (MPa) 2204 2086 2179 Hardness (HRA) 93.3 93.3 93.2 <![CDATA[Fracture toughness (MPa·m 1 / 2 )]]> 9.5 9.6 9.9

[0059] Table 5 shows the volume fraction of agglomerates of the cermets prepared using the process described in Example 2.

[0060] Aggregates <![CDATA[1 # ]]> <![CDATA[2 # ]]> <![CDATA[3 # ]]> Small size (20μm≤particle size≤40μm) 2.1% 3.8% 3.1% Medium size (40μm < particle size ≤ 100μm) 17.5% 16.1% 18.7% Large size (100μm < particle size ≤ 150μm) 20.7% 21.2% 21.3%

[0061] Example 3

[0062] 1. Preparation of mixed slurry: Prepare three kinds of mixtures according to the components in Table 1, add anhydrous ethanol as the ball milling medium, the amount of which is 1.5 times the weight of the mixture, place it in a planetary ball mill and ball mill at a speed of 260 rpm for 20 hours;

[0063] 2. Fluidized Bed Drying: Pour the slurry obtained in step 1 into a bubbling fluidized bed. The inlet air temperature is 110℃, the fluidizing gas velocity is 2m / s, the fluidizing gas is air, the bed height is 50mm, and the area occupied by 30,000 mesh nylon mesh is 45% of the total area of ​​the bed, 20,000 mesh nylon mesh is 30%, and 15,000 mesh nylon mesh is 25%. The nylon mesh structure is as follows. Figure 5 As shown; Figure 5 In the middle, there is a 6-stainless steel pressure strip, and the AC is 30000 / 20000 / 15000 mesh nylon mesh respectively.

[0064] 3. Compression molding: The powder obtained in step 2 is compressed into a tablet using a tablet press at a pressure of 200 MPa.

[0065] 4. Vacuum sintering: The process is carried out in a vacuum sintering furnace. The temperature is increased to 1000℃ at a rate of 6℃ / min and held for 1 hour with a vacuum of 7 Pa. Then, the temperature is increased to 1300℃ at a rate of 3℃ / min and held for 4 hours with a vacuum of 7 Pa. Next, the temperature is increased to 1450℃ at a rate of 2℃ / min and held for 10 minutes. Then, the temperature is decreased to 1350℃ at a rate of 10℃ / min and held for 8 hours with a vacuum of 35 Pa. Finally, the temperature is decreased to below 1100℃ at a rate of 10℃ / min and then cooled with the furnace with a vacuum of 7 Pa.

[0066] Under the above preparation process conditions, the mechanical properties of the metal ceramics prepared with different component ratios are shown in Table 6, and the volume fraction of agglomerates of the metal ceramics prepared with different component ratios are shown in Table 7.

[0067] Table 6 shows the mechanical properties of different composition metal ceramics prepared using the process described in Example 3.

[0068] Element <![CDATA[1 # ]]> <![CDATA[2 # ]]> <![CDATA[3 # ]]> Bending strength (MPa) 2297 2174 2089 Hardness (HRA) 93.5 93.4 93.3 <![CDATA[Fracture toughness (MPa·m 1 / 2 ).]]> 9.6 10.1 9.7

[0069] Table 7 shows the volume fraction of agglomerates in the cermets prepared using the process described in Example 3.

[0070] Aggregates <![CDATA[1 # ]]> <![CDATA[2 # ]]> <![CDATA[3 # <!-- 6 -->]]> Small size (20μm≤particle size≤40μm) 3.9% 5.2% 4.4% Medium size (40μm < particle size ≤ 100μm) 22.7% 24.7% 19.6% Large size (100μm < particle size ≤ 150μm) 21.4% 26.2% 23.2%

[0071] The above embodiments are merely for illustrating the content of the present invention and are not intended to limit it. Therefore, any changes that fall within the meaning and scope equivalent to the claims of the present invention should be considered as included within the scope of the claims.

[0072] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A multi-scale honeycomb structure Ti(C,N)-based cermet, characterized in that, The cermet is composed of fine-grained agglomerates of different sizes and a coarse-grained matrix surrounding them; the fine-grained agglomerates are composed of hard phase particles with core-ring structures, hard phase particles without core structures, and Ni-based binder phases; the coarse-grained matrix is ​​composed of hard phase particles with core-ring structures and Ni-based binder phases. The core-ring structure of the hard phase particles has a core component of Ti(C,N) and a ring phase component of (Ti,Mo,W,Ta,Nb)(C,N); the coreless hard phase particles have a component of (Ti,Mo,W,Ta,Nb)(C,N). The fine-grained agglomerates of different sizes account for 33.4% to 56.1% of the volume fraction of the cermet, of which small fine-grained agglomerates with a particle size of 20 to 40 μm account for 1.6% to 5.2% of the volume fraction; medium-fine-grained agglomerates with a particle size of 40 to 100 μm account for 1.6% to 5.2% of the volume fraction; and large fine-grained agglomerates with a particle size of 100 to 150 μm account for 16.5% to 26.2% of the volume fraction. The cermet is composed of the following raw materials in the indicated mass percentages: Ti: 50.56~53.92%, W: 1.96~2.04%, Ta: 1.48~1.52%, Nb: 1.87~1.93%, Mo: 7.51~8.18%, Ni: 11.91~16.23%, C: 12.61~14.29%, N: 6.93~7.06%.

2. A method for preparing a multi-scale honeycomb structure Ti(C,N)-based cermet as described in claim 1, characterized in that, The specific steps are as follows: 1) Mix Ti(C,N) powder, WC powder, TaC powder, NbC powder, Mo2C powder, Ni powder, and graphite powder, all with a particle size of 2~4μm, to obtain a mixed powder; the mixed powder contains, by mass percentage: Ti: 50.56~53.92%, W: 1.96~2.04%, Ta: 1.48~1.52%, Nb: 1.87~1.93%, Mo: 7.51~8.18%, Ni: 11.91~16.23%, C: 12.61~14.29%, N: 6.93~7.06%; 2) Place the mixed powder obtained in step 1) into a ball mill jar for mixing to obtain a mixed slurry; 3) The mixed slurry obtained in step 2) is poured into a fluidized bed equipped with a perforated plate for drying to obtain a mixed powder; the perforated plate is equipped with a nylon mesh, and the nylon mesh contains mesh holes of different sizes; 4) The mixed powder obtained in step 3) is pressed into shape and vacuum sintered to obtain Ti(C,N)-based metal ceramics with multi-scale honeycomb structure.

3. The method for preparing multi-scale honeycomb structure Ti(C,N)-based cermets according to claim 2, characterized in that, The mixing process mentioned in step 2) refers to adding anhydrous ethanol for mixing, and the mass of the added anhydrous ethanol is 1.3 to 1.5 times the weight of the mixed powder.

4. The method for preparing multi-scale honeycomb structure Ti(C,N)-based cermets according to claim 2, characterized in that, In step 3), the inlet temperature of the fluidized bed is 90~110℃, the fluidizing gas velocity is 0.5~2m / s, the fluidizing gas is air, and the bed height is 50~70mm.

5. The method for preparing multi-scale honeycomb structure Ti(C,N)-based cermets according to claim 2, characterized in that, Step 3) The nylon mesh includes three mesh sizes: 30,000 mesh, 20,000 mesh, and 15,000 mesh. Among them, the 30,000 mesh accounts for 35-45% of the area of ​​the nylon mesh, the 20,000 mesh accounts for 25-35% of the area of ​​the nylon mesh, and the 15,000 mesh accounts for 25-35% of the area of ​​the nylon mesh.

6. The method for preparing multi-scale honeycomb structure Ti(C,N)-based cermets according to claim 2, characterized in that, In step 3), the nylon mesh has meshes of the same aperture size clustered together and distributed alternately with meshes of other aperture sizes.

7. The method for preparing multi-scale honeycomb structure Ti(C,N)-based cermets according to claim 2, characterized in that, In step 4), the pressing pressure is 150~200MPa.

8. The method for preparing multi-scale honeycomb structure Ti(C,N)-based cermets according to claim 2, characterized in that, In step 4), the vacuum sintering is divided into the following four stages: the first stage: heating at 6℃ / min to 800~1000℃, holding for 1~1.5h, with a vacuum degree of 5~7Pa; the second stage: heating at 3℃ / min to 1260~1300℃, holding for 2~4h, with a vacuum degree maintained at 5~7Pa; the third stage: heating at 2℃ / min to 1450~1480℃, holding for 5~10min, then cooling at a rate of 10℃ / min to 1320~1360℃, holding for 6~8h, with a vacuum degree of 30~35Pa; the fourth stage: cooling at a rate of 10℃ / min to below 1100℃ and then cooling with the furnace, with a vacuum degree of 5~7Pa.

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