A gradient structure wear-resistant composite material and preparation method thereof

Abstract

The present invention relates to a gradient structure wear-resistant composite material and a preparation method thereof, and belongs to the technical field of powder metallurgy. The present invention solves the technical problems in the prior art that cemented carbide is relatively expensive and has poor impact resistance. The preparation method of the present invention comprises the following steps: first vacuum-evaporating fine-grained wear-resistant material powder on the surface of coarse-grained wear-resistant material particles, and then uniformly mixing the obtained surface-modified coarse-grained wear-resistant material particles and fine-grained wear-resistant material powder with a solvent containing a dispersant to obtain a composite slurry; then pouring the composite slurry into a mold, vibrating the mold, heating to remove the solvent, and finally placing the mold on a hot press and sintering to obtain a gradient structure wear-resistant composite material. In the material, the coarse-grained wear-resistant material is distributed in a gradient in the fine-grained wear-resistant material, and can exhibit good properties such as strength, toughness and wear resistance under working conditions such as high-speed impact and long-term wear.

Description

Technical Field

[0001] The invention belongs to the technical field of powder metallurgy, and in particular relates to a gradient structure wear-resistant composite material and a preparation method thereof. Background Art

[0002] Cemented carbide is a composite material typically manufactured using powder metallurgy, using a refractory metal hard compound (such as WC or TiC) as the hard phase and a transition metal (such as Fe, Co, Ni, and their alloys or high-entropy alloys) as the binder phase. Cemented carbide exhibits high hardness, strength, wear resistance, and corrosion resistance, and is widely used in military, aerospace, machining, metallurgy, oil drilling, mining tools, electronics, communications, and construction.

[0003] However, cemented carbide is expensive and has poor impact resistance. In order to further expand the application field of cemented carbide, it is necessary to improve the impact resistance of cemented carbide.

[0004] Introducing a gradient structure is a way to modify cemented carbide. For example, a Chinese patent discloses a high-cobalt YG cemented carbide with a gradient structure for forming a mold and a preparation method (publication number 115725884A). This method adds a trace amount of TiN powder to the raw materials Co powder, W powder and WC powder used to prepare the high-cobalt YG cemented carbide, and improves the hardness and plastic deformation resistance of the high-cobalt YG cemented carbide through the second hard phase TiN. At the same time, the strong thermodynamic coupling between Ti and N is used to obtain a cemented carbide with a composition gradient structure, so that the surface of the cemented carbide still maintains the WC-Co two-phase structure and maintains high toughness. Moreover, the gradient cemented carbide after sintering is cryogenically treated to compensate for the reduction in the transverse fracture strength of the YG cemented carbide caused by the introduction of TiN, thereby preparing a high-cobalt YG cemented carbide with a gradient structure having high hardness, strong plastic deformation resistance and high strength. However, in the prior art, the gradient modification of cemented carbide is basically concentrated on the crystal phase structure, and is not modified for the impact resistance of the cemented carbide. Summary of the Invention

[0005] In view of this, the present invention provides a gradient structure wear-resistant composite material and a preparation method thereof to solve the technical problems in the prior art that cemented carbide is expensive and has poor impact resistance.

[0006] The technical solutions adopted by the present invention to solve the above technical problems are as follows.

[0007] The preparation method of the gradient structure wear-resistant composite material of the present invention comprises the following steps:

[0008] Step 1: uniformly mixing coarse-grained wear-resistant material particles and fine-grained wear-resistant material powder at a volume ratio of 1:100 to 100:1, and vacuum evaporating to obtain surface-modified coarse-grained wear-resistant material particles;

[0009] The coarse-grained wear-resistant material particles are a kind of cemented carbide particles or a mixture of multiple cemented carbide particles. The particle size range of the coarse-grained wear-resistant material particles is D 50 1~200mm;

[0010] The fine-grained wear-resistant material powder is ferroalloy powder, and the particle size range of the fine-grained wear-resistant material powder is D 50 0.1~200μm;

[0011] Step 2: uniformly mixing the surface-modified coarse-grained wear-resistant material particles, the fine-grained wear-resistant material powder remaining in step 1, and a solvent containing a dispersant to obtain a composite slurry;

[0012] Step 3: pouring the composite slurry into a mold, vibrating the mold, and heating to remove the solvent in the composite slurry after the vibration is completed;

[0013] The vibration conditions are: vibration frequency of 10Hz to 5000Hz, acceleration of 1m / s 2 ~1000m / s 2 , duration is 0.001h~10h;

[0014] Step 4: Pressurize and sinter the mold to obtain a gradient structure wear-resistant composite material.

[0015] Preferably, in step 1, the coarse-grained wear-resistant material particles are a mixture of one or more of WC-based cemented carbide particles, TiC-based cemented carbide particles, TiCN-based cemented carbide particles and TiN-based cemented carbide particles.

[0016] Preferably, in step 1, the vacuum evaporation conditions are: vacuum degree ≤-0.01 MPa, temperature 600-1200° C., and time 0.1-200 h.

[0017] Preferably, in step 1, the ferroalloy powder is manganese steel alloy powder.

[0018] Preferably, in step 2, the solvent is ethanol.

[0019] Preferably, in step 2, the dispersant is a mixture of one or more of polyvinyl alcohol, polyethylene glycol, polyvinyl butyral, and stearic acid.

[0020] Preferably, in step 2, the amount of the dispersant is 0.001 wt.% to 10 wt.% of the mass of the fine-grained wear-resistant material powder in step 1, more preferably 0.01 wt.% to 1 wt.%, and particularly preferably 0.01 wt.% to 0.1 wt.%.

[0021] Preferably, in step 2, uniform mixing is achieved by roller wet grinding; more preferably, the grinding balls used in roller wet grinding are steel balls, carbide balls or ceramic balls; more preferably, the conditions for roller wet grinding are: ball-to-material ratio of 0.1:10 to 10:0.1, ball milling time of 2h to 48h, and solid content of 10vol.% to 80vol.%.

[0022] Preferably, in step three, the heating temperature is 30° C. to 150° C., and the heating time is 0.1 h to 10 h.

[0023] Preferably, in step 4, the pressure range is 0.1 MPa to 100 MPa, the heating rate is 0.01° C. / min to 30° C. / min, the sintering temperature is 800° C. to 1400° C., and the sintering time is 0.1 h to 10 h.

[0024] The present invention also provides a gradient structure wear-resistant composite material prepared by the preparation method of the gradient structure wear-resistant composite material.

[0025] The principle of the present invention is:

[0026] The preparation method of the gradient structure wear-resistant composite material of the present invention is to evaporate a layer of fine-grained wear-resistant material powder on the surface of the coarse-grained wear-resistant material particles, which can reduce the potential difference between the coarse-grained wear-resistant material particles and the fine-grained wear-resistant material powder in the solvent when the two are mixed, thereby reducing the sedimentation difference between the two, making it difficult for the fine-grained powder to settle to the bottom during the subsequent vibration process, and then utilizing the different performance behaviors of the surface-modified coarse-grained wear-resistant material particles and the fine-grained wear-resistant material powder in the mixed slurry under the same vibration conditions to regulate the gradient structure. Specifically, the greater the acceleration, the easier it is for the surface-modified coarse-grained wear-resistant material particles to move downward; the vibration frequency is suitable for better controlling the gradient distribution of the surface-modified coarse-grained wear-resistant material particles. If a layer of fine-grained wear-resistant material powder is not evaporated on the surface of the coarse-grained wear-resistant material particles, or if the acceleration and vibration frequency are not controlled, the fine-grained wear-resistant material powder will easily settle to the bottom, making it difficult for the coarse-grained wear-resistant material particles to achieve a gradient distribution. In addition, after the coarse-grained wear-resistant material particles are evaporated with a layer of fine-grained wear-resistant material powder, it is beneficial to the sintering density in the subsequent process.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] The present invention's method for preparing a gradient-structured wear-resistant composite material involves vapor-depositing a layer of fine-grained wear-resistant material powder onto the surface of coarse-grained wear-resistant material particles to reduce the difference in sedimentation between the two. The method then combines vibration to form a gradient distribution of the coarse-grained wear-resistant material, thereby producing the gradient-structured wear-resistant composite material. This method is simple to operate and suitable for large-scale production. Furthermore, the gradient distribution can be controlled by adjusting the ratio of the surface-modified coarse-grained wear-resistant material particles to the fine-grained wear-resistant material powder, as well as parameters such as the vibration frequency and duration.

[0029] The gradient structure wear-resistant composite material prepared by the present invention is composed of coarse-grained wear-resistant material particles with excellent hardness and wear resistance and fine-grained wear-resistant material powder with excellent impact toughness. The coarse-grained wear-resistant material particles are distributed in a gradient within the fine-grained wear-resistant material powder. In the composite material, the surface with more coarse-grained wear-resistant material particles exhibits good wear resistance, while the surface with more fine-grained wear-resistant material powder exhibits good impact resistance. The present invention enables the wear-resistant composite material to exhibit good strength, toughness, and wear resistance under working conditions such as high-speed impact and long-term wear. It is particularly suitable for working conditions with high requirements for wear resistance and impact toughness, such as the inner lining of a ball mill, the track pins of a crawler vehicle, and the bucket teeth of an excavator. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0031] Figure 1 The present invention is a process flow chart of the preparation method of the gradient structure wear-resistant composite material.

[0032] Figure 2 It is a schematic diagram of the bottom cross section of the gradient structure wear-resistant composite material of the present invention.

[0033] Figure 3 It is a schematic diagram of the longitudinal section of the gradient structure wear-resistant composite material of the present invention.

[0034] Figure 4 This is a schematic diagram of the bottom cross section of the gradient structure wear-resistant composite material according to Example 1 of the present invention.

[0035] Figure 5 This is a schematic diagram of the longitudinal section of the gradient structure wear-resistant composite material according to Example 1 of the present invention. DETAILED DESCRIPTION

[0036] In order to further understand the present invention, preferred embodiments of the present invention are described below. However, it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention, rather than limiting the claims of the present invention.

[0037] The preparation method of the gradient structure wear-resistant composite material of the present invention comprises the following steps:

[0038] Step 1: uniformly mixing coarse-grained wear-resistant material particles and fine-grained wear-resistant material powder at a volume ratio of 1:100 to 100:1, vacuum evaporating, and forming a layer of fine-grained wear-resistant material powder on the surface of the coarse-grained wear-resistant material particles to obtain surface-modified coarse-grained wear-resistant material particles;

[0039] Step 2: uniformly mixing the surface-modified coarse-grained wear-resistant material particles, the fine-grained wear-resistant material powder remaining in step 1, and a solvent containing a dispersant to obtain a composite slurry;

[0040] Step 3: pouring the composite slurry into a mold, vibrating the mold to form a gradient distribution of the surface-modified coarse-grained wear-resistant material particles, and at the same time, removing the gas in the composite slurry so that the composite slurry fully fills the mold, and then heating to remove the solvent;

[0041] Step 4: Pressurize and sinter the mold to completely sinter and densify the surface-modified coarse-grained wear-resistant material particles and the fine-grained wear-resistant material powder to form a metallurgical bond, thereby obtaining a gradient structure wear-resistant composite material.

[0042] In the above technical solution, in step one, the coarse-grained wear-resistant material particles are a type of cemented carbide particles or a mixture of multiple cemented carbide particles. When it is a mixture of multiple cemented carbide particles, the mixing ratio is not particularly limited and can be set as required. The coarse-grained wear-resistant material particles have good wear resistance and provide hardness and wear resistance for the composite material. Preferably, the coarse-grained wear-resistant material particles are a mixture of one or more of WC-based cemented carbide particles, TiC-based cemented carbide particles, TiCN-based cemented carbide particles and TiN-based cemented carbide particles in any proportion, more preferably YG6 cemented carbide particles, YG8 cemented carbide particles, YT15 cemented carbide particles, and YW1 cemented carbide particles. However, it should be noted that other cemented carbide particles well known to those skilled in the art are also applicable to the present invention. The coarse-grained wear-resistant material particles are millimeter-sized particles with a particle size range D50 of 1 to 200 mm, preferably 8 to 15 mm, and more preferably 8 to 10 mm.

[0043] In the above technical solution, in step 1, the fine-grained wear-resistant material powder is an iron alloy powder, preferably a manganese steel alloy powder, such as manganese steel MN600, manganese steel MN400, 316L, QT900-2. The fine-grained wear-resistant material powder has good impact resistance and provides impact toughness for the composite material. The fine-grained wear-resistant material powder is a micron-sized powder with a particle size range of D 50 It is 0.1 to 200 μm, preferably 50 to 100 μm, and more preferably 50 to 80 μm.

[0044] In the above technical solution, in step 1, a layer of fine-grained wear-resistant material powder is evaporated on the surface of the coarse-grained wear-resistant material particles. This ensures that the coarse-grained wear-resistant material particles and the fine-grained wear-resistant material powder in the solvent have similar electrical potentials when the two are mixed, thereby reducing the difference in sedimentation between the two. The volume ratio of the coarse-grained wear-resistant material particles to the fine-grained wear-resistant material powder is preferably 1:100 to 10:1, more preferably 1:2 to 1:4, and particularly preferably 1:3.

[0045] In the above technical solution, in step 1, vacuum evaporation is typically performed in a vacuum tank. The vacuum evaporation conditions are preferably: vacuum ≤ -0.01 MPa, temperature 600-1200°C, and time 0.1-200 hours. It should be noted that other vacuum evaporation conditions can be used by those skilled in the art to achieve the same effect, as long as a layer of fine-grained wear-resistant material powder can be deposited on the surface of the coarse-grained wear-resistant material particles.

[0046] In the above technical solution, in step 2, the solvent is not particularly limited, and can play the role of dispersing the dispersant, the surface-modified coarse-grained wear-resistant material particles and the fine-grained wear-resistant material powder, preferably ethanol. Those skilled in the art can also select other solvents that can achieve the above-mentioned effects as needed.

[0047] In the above technical solution, in step 2, the mixture is uniformly mixed by wet drum milling. Preferably, the grinding balls used in the wet drum milling are steel balls, carbide balls, or ceramic balls. The ball-to-material ratio is 0.1:10 to 10:0.1, preferably 1 to 2:1, and more preferably 1.5:1. The milling time is 2 to 48 hours, preferably 1.5 to 6 hours, and more preferably 3 to 4 hours. The solid content is 10 to 80 vol.%, preferably 20 to 30 vol.%, and more preferably 25 vol.%. It should be noted that other mixing methods well known to those skilled in the art are also acceptable.

[0048] In the above technical solution, in step 2, the dispersant is a conventional auxiliary agent in the art, which plays a role in promoting dispersion. The preferred dispersant in this embodiment is a mixture of one or more of polyvinyl alcohol, polyethylene glycol, polyvinyl butyral, and stearic acid. When it is a mixture of multiple dispersants, the mixing ratio is not particularly limited and can be set as required. The amount of dispersant is 0.001wt.% to 10wt.% of the mass of the fine-grained wear-resistant material powder in step 1. Preferably, 0.01wt% to 1wt%, more preferably 0.01wt% to 0.1wt%.

[0049] In the above technical solution, in step 3, the mold is usually placed on a vibration table to achieve vibration. The vibration frequency is 10Hz to 5000Hz, preferably 30Hz to 200Hz, more preferably 50Hz to 100Hz; the acceleration is 1m / s 2 ~1000m / s 2 , preferably 80m / s 2 ~200m / s 2 , more preferably 100 m / s 2 ~200m / s 2 The duration is 0.001h to 10h, preferably 0.01h to 0.5h, and more preferably 0.1h to 0.5h. Vibration is the core of the present invention. Vibration can achieve a gradient distribution of surface-modified cemented carbide particles in fine-grained wear-resistant material powder (i.e., the distribution of cemented carbide particles is gradient, with density increasing from top to bottom). The gradient distribution can be controlled by adjusting the ratio of surface-modified coarse-grained wear-resistant material particles to fine-grained wear-resistant material powder, parameters such as vibration frequency and vibration duration.

[0050] In the above technical solution, in step 3, the heating temperature is preferably 30°C to 150°C, more preferably 70°C to 80°C; the heating time is preferably 0.1h to 10h, more preferably 1h to 4h, and particularly preferably 2h to 3h. The heating equipment is typically a blast drying oven. It should be noted that other heating equipment known to those skilled in the art is also applicable to the present invention.

[0051] In the above technical solution, in step 4, the preferred pressure range is 0.1MPa to 100MPa, more preferably 10 to 30MPa, and particularly preferably 12MPa; the heating rate is preferably 0.01°C / min to 30°C / min, more preferably 5°C / min to 12°C / min, and particularly preferably 8°C / min to 12°C / min; the sintering temperature depends on the material, preferably 800°C to 1400°C, and the sintering time is preferably 0.1h to 10h, more preferably 1 to 2h. A press is usually selected as the equipment for mold pressure sintering. However, it should be noted that other pressure sintering equipment known to those skilled in the art is also applicable to the present invention.

[0052] like Figure 2 and Figure 3 As shown, the gradient structure wear-resistant composite material prepared by the preparation method of the gradient structure wear-resistant composite material of the present invention is composed of coarse-grained wear-resistant material particles with excellent hardness and wear resistance and fine-grained wear-resistant material powder with excellent impact toughness. The coarse-grained wear-resistant material particles are distributed in a gradient within the fine-grained wear-resistant material powder. In the composite material, the surface with more coarse-grained wear-resistant material particles exhibits good wear resistance, while the surface with more fine-grained wear-resistant material powder exhibits good impact resistance. This composite material is particularly suitable for working conditions with high requirements for wear resistance and impact toughness, such as the lining of ball mills, the track pins of crawler vehicles, and the bucket teeth of excavators.

[0053] The terms used in the present invention generally have the meanings commonly understood by those skilled in the art, unless otherwise specified. In order to enable those skilled in the art to better understand the technical solutions of the present invention, the present invention will be further described in detail below with reference to the embodiments.

[0054] In the following examples, various processes and methods not described in detail are conventional methods known in the art. Unless otherwise specified, the materials, reagents, devices, instruments, equipment, etc. used in the following examples can be obtained from commercial sources.

[0055] The present invention is further described below with reference to the examples.

[0056] Example 1

[0057] Weigh 5 kg of YG6 cemented carbide particles (D 50 15mm) and 10Kg manganese steel NM600 powder (D 50 50μm) and mixed, put into a vacuum tank, evacuate to -0.01MPa, and evaporate at 800℃ for 2h to evaporate a layer of manganese steel NM600 powder on the surface of YG6 cemented carbide particles to obtain surface-modified YG6 cemented carbide particles.

[0058] After cooling to room temperature, the surface-modified YG6 cemented carbide particles and the remaining NM600 manganese steel powder from step 1 were added to an ethanol solution containing a dispersant (stearic acid, 0.01 wt.% per 10 kg of NM600 manganese steel powder). The mixture was mixed thoroughly by roller wet milling and ball milling for 3 hours to obtain a composite slurry. The grinding balls used were YG6 cemented carbide balls with a ball-to-material ratio of 1:1. The solids content was 20 vol.%.

[0059] The composite slurry is poured into a mold placed on a vibration table. The slurry is fully filled into the mold through vibration, and the surface-modified YG6 cemented carbide particles sink and form a gradient distribution. The vibration table parameters are set as follows: vibration frequency is 100 Hz, acceleration is 100 m / s2 , lasting for 0.01h. Then, the mold was placed in a forced air drying oven at 80℃ and baked for 2h to remove the solvent.

[0060] Finally, the mold was placed on a hot press and pressurized to 10 MPa. At the same time, the temperature was raised to 1100°C at a rate of 5°C / min and kept at that temperature for 2 hours, so that the surface-modified YG6 cemented carbide particles and manganese steel NM600 powder were sintered and densified into a powder / particle wear-resistant composite material with a gradient structure.

[0061] The hardness, impact toughness, and wear resistance of the gradient structure powder / particle wear-resistant composite material prepared in Example 1 were tested. The hardness test standard was GB / T 230.1-2018, the impact toughness test standard was GB / T 229-2020, and the wear resistance test standard was GB / T 34501-2017. The wear-resistant composite material had a hardness of 49.9 HRC and an impact toughness of 4.2 J / cm 2 , abrasive wear 1.1g / 10min.

[0062] The powder / particle wear-resistant composite material with gradient structure prepared in Example 1 was cut longitudinally and transversely at the bottom, and the results were as follows: Figure 5 and Figure 4 As shown, from Figure 5 and Figure 4 It can be seen that in the wear-resistant composite material prepared in Example 1, the coarse-grained wear-resistant material particles are distributed in a gradient in the fine-grained wear-resistant material powder.

[0063] Example 2

[0064] Weigh 5 kg of YG8 cemented carbide particles (D 50 13mm) and 15Kg manganese steel NM400 powder (D 50 80μm) and mixed, put into a vacuum tank, evacuate to -0.01MPa, and evaporate at 720℃ for 1.5h to evaporate a layer of manganese steel NM400 powder on the surface of YG8 cemented carbide particles to obtain surface-modified YG8 cemented carbide particles.

[0065] After cooling to room temperature, the surface-modified YG8 cemented carbide particles and the remaining NM400 manganese steel powder from step 1 were added to an ethanol solution containing a dispersant (0.05 wt.% polyvinyl alcohol per 15 kg of NM400 manganese steel powder). The mixture was mixed thoroughly by roller wet milling and ball milling for 6 hours to obtain a composite slurry. The grinding balls used were steel balls with a ball-to-material ratio of 1.5:1. The solids content was 20 vol.%.

[0066] The composite slurry is poured into a mold placed on a vibration table. The slurry is fully filled into the mold through vibration, and the surface-modified YG8 cemented carbide particles sink and form a gradient distribution. The vibration table parameters are set as follows: vibration frequency is 200HZ, acceleration is 200m / s 2 , lasting for 0.01h. Then, the mold was placed in a forced air drying oven at 80℃ and baked for 3h to remove the solvent.

[0067] Finally, the mold was placed on a hot press and pressurized to 30 MPa. The temperature was then raised to 1100°C at a rate of 12°C / min and held for 2 hours. This allowed the surface-modified YG8 carbide particles and manganese steel NM400 powder to sinter and densify into a gradient-structured powder / particle wear-resistant composite material. Testing revealed that the wear-resistant composite material had a hardness of 57.4 HRC and an impact toughness of 5.1 J / cm. 2 The abrasive wear rate is 1.1 g / 10 min, and the coarse-grained wear-resistant material particles are distributed in a gradient in the fine-grained wear-resistant material powder. The testing standard is the same as that of Example 1.

[0068] Example 3

[0069] Weigh 4 kg of YT15 cemented carbide particles (D 50 10mm) and 16Kg 316L powder (D 50 50μm) and mixed, put into a vacuum tank, evacuate to -0.01MPa, and evaporate at 850℃ for 1.5h to evaporate a layer of 316L powder on the surface of YT15 cemented carbide particles to obtain surface-modified YT15 cemented carbide particles.

[0070] After cooling to room temperature, the surface-modified YT15 carbide particles and the remaining 316L powder from step 1 were added to an ethanol solution containing a dispersant (polyethylene glycol, 0.06 wt.% per 16 kg of 316L powder). The mixture was then wet-rolled and ball-milled for 4 hours to obtain a composite slurry. YT15 carbide balls were used, with a ball-to-powder ratio of 1:1. The solids content was 30 vol.%.

[0071] The composite slurry is poured into a mold placed on a vibration table. The slurry is fully filled into the mold through vibration, and the surface-modified YT15 cemented carbide particles sink and form a gradient distribution. The vibration table parameters are set as follows: vibration frequency of 50HZ, acceleration of 80m / s 2 , lasting for 0.5 hours. Subsequently, the mold was placed in a blast drying oven at 70°C and baked for 1 hour to remove the solvent.

[0072] Finally, the mold was placed on a hot press and pressurized to 12 MPa. The temperature was then raised to 1350°C at a rate of 10°C / min and held for 1 hour. This allowed the surface-modified YT15 carbide particles and 316L powder to sinter and densify into a powder / particle wear-resistant composite material with a gradient structure. Testing revealed that the wear-resistant composite material had a hardness of 53.2 HRC and an impact toughness of 4.2 J / cm 2 The abrasive wear rate is 1.4 g / 10 min, and the coarse-grained wear-resistant material particles are distributed in a gradient in the fine-grained wear-resistant material powder. The testing standard is the same as that of Example 1.

[0073] Example 4

[0074] Weigh 10 kg of YW1 cemented carbide particles (D 50 8mm) and 20Kg QT900-2 powder (D 50 100 μm) and mixed, put into a vacuum tank, evacuate to -0.01 MPa, and evaporate at 650 ° C for 4 h to evaporate a layer of QT900-2 on the surface of the YW1 cemented carbide particles to obtain surface-modified YW1 cemented carbide particles.

[0075] After cooling to room temperature, the surface-modified YW1 cemented carbide particles and the remaining QT900-2 powder from step 1 were added to an ethanol solution containing a dispersant (polyvinyl butyral, 0.05 wt.% per 20 kg of QT900-2 powder). The mixture was mixed thoroughly by roller milling and ball milling for 1.5 hours to obtain a composite slurry. The grinding balls used were cemented carbide balls with a ball-to-powder ratio of 2:1. The solids content was 25 vol.%.

[0076] The composite slurry is poured into a mold placed on a vibration table. The slurry is fully filled into the mold through vibration, and the surface-modified YW1 cemented carbide particles sink and form a gradient distribution. The vibration table parameters are set as follows: vibration frequency of 30HZ, acceleration of 80m / s 2 , lasting for 0.1h. Then, the mold was placed in a blast drying oven at 70℃ and baked for 4h to remove the solvent.

[0077] Finally, the mold was placed on a hot press and pressurized to 12 MPa. The temperature was then raised to 1000°C at a rate of 8°C / min and held for 1 hour. This allowed the surface-modified YW1 carbide particles and QT900-2 powder to sinter and densify into a powder / particle wear-resistant composite material with a gradient structure. Testing revealed that the wear-resistant composite material had a hardness of 58.3 HRC and an impact toughness of 5.1 J / cm 2 The abrasive wear rate is 1.3 g / 10 min, and the coarse-grained wear-resistant material particles are distributed in a gradient in the fine-grained wear-resistant material powder. The testing standard is the same as that of Example 1.

[0078] Obviously, the above embodiments are merely examples for clarity of explanation and are not intended to limit the embodiments. Those skilled in the art will appreciate that other variations or modifications can be made based on the above description. It is not necessary and impossible to enumerate all embodiments here. Obvious variations or modifications arising therefrom remain within the scope of protection of the present invention.

Claims

1. A method for preparing a gradient structure wear-resistant composite material, characterized in that: Here are the steps: Step 1: uniformly mixing coarse-grained wear-resistant material particles and fine-grained wear-resistant material powder at a volume ratio of 1:100 to 100:1, and vacuum-depositing the mixture to obtain surface-modified coarse-grained wear-resistant material particles; The coarse-grained wear-resistant material particles are a kind of cemented carbide particles or a mixture of multiple cemented carbide particles. The particle size range of the coarse-grained wear-resistant material particles is D 50 1~200mm; The fine-grained wear-resistant material powder is ferroalloy powder, and the particle size range of the fine-grained wear-resistant material powder is D 50 0.1~200μm; Step 2: uniformly mixing the surface-modified coarse-grained wear-resistant material particles, the fine-grained wear-resistant material powder remaining in step 1, and a solvent containing a dispersant to obtain a composite slurry; Step 3: pouring the composite slurry into a mold, vibrating the mold, and heating to remove the solvent in the composite slurry after the vibration is completed; The vibration conditions are: vibration frequency of 10Hz to 5000Hz, acceleration of 1m / s 2 ~1000m / s 2 , duration is 0.001h~10h; Step 4: Pressurize and sinter the mold to obtain a gradient structure wear-resistant composite material.

2. The method for preparing the gradient structure wear-resistant composite material according to claim 1, characterized in that: In step 1, the coarse-grained wear-resistant material particles are a mixture of one or more of WC-based cemented carbide particles, TiC-based cemented carbide particles, TiCN-based cemented carbide particles, and TiN-based cemented carbide particles.

3. The method for preparing the gradient structure wear-resistant composite material according to claim 1, characterized in that: In step 1, the ferroalloy powder is manganese steel alloy powder.

4. The method for preparing the gradient structure wear-resistant composite material according to claim 1, characterized in that: In step 1, the vacuum evaporation conditions are: vacuum degree ≤-0.01 MPa, temperature 600-1200° C., and time 0.1-200 h.

5. The method for preparing the gradient structure wear-resistant composite material according to claim 1, characterized in that: In step 2, the solvent is ethanol.

6. The method for preparing the gradient structure wear-resistant composite material according to claim 1, characterized in that: In step 2, the dispersant is a mixture of one or more of polyvinyl alcohol, polyethylene glycol, polyvinyl butyral, and stearic acid; the amount of the dispersant used is 0.001wt.% to 10wt.% of the mass of the fine-grained wear-resistant material powder in step 1.

7. The method for preparing the gradient structure wear-resistant composite material according to claim 1, characterized in that: In step 2, uniform mixing is achieved by roller wet grinding. The grinding balls used in roller wet grinding are steel balls, carbide balls or ceramic balls. The conditions of roller wet grinding are: ball-to-material ratio of 0.1:10 to 10:0.1, ball milling time of 2h to 48h, and solid content of 10vol.% to 80vol.%.

8. The method for preparing the gradient structure wear-resistant composite material according to claim 1, characterized in that: In step 3, the heating temperature is 30° C. to 150° C., and the heating time is 0.1 h to 10 h.

9. The method for preparing the gradient structure wear-resistant composite material according to claim 1, characterized in that: In step 4, the pressure range of the pressurization is 0.1MPa to 100MPa, the heating rate is 0.01°C / min to 30°C / min, the sintering temperature is 800°C to 1400°C, and the sintering time is 0.1h to 10h.

10. A wear-resistant composite material with a gradient structure prepared by the method for preparing a wear-resistant composite material with a gradient structure according to any one of claims 1 to 9.

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